Pharma Machineries - API, Formulation, Packaging Made Easy

AUTOMATION - THE FUTURE OF INDUSTRIAL FILTRATION AND DRYING

2025-02-28T02:10:00.000+05:30

INTRODUCTION TO INDUSTRIAL AUTOMATION - IN RELATION TO - MANUFACTURING OF PHARMACEUTICAL, CHEMICAL, AGROCHEMICAL AND ALLIED INDUSTRIES

Industrial automation refers to man-less execution of the operations or tasks involved in the manufacturing sector, with the help of technological advancements in applied physics, electronics, electrical and mechanical engineering, computer programming and robotics.

Industrial Automation gained the most prestigious position in the entire manufacturing process. As a concept, something started shaping up in 18th century gradually evolved yielding sophistication in terms of PLC (Programmable Logic Control), DCS (Distributed Control System), SCADA (Supervisory Control and Data Acquisition), controlling the chemical reactions, mechanical and thermal operations with the help of hydraulically, pneumatically, electrically powered valves and instruments.

CURRENT SCENARIO (PROBLEMS THAT THE MANUFACTURING COMPANIES FACE):

Chemicals and Specialty Chemicals, Pharma, Food Processing, Petrochemicals and many other industries which involves Unit Operations, as well as, Formulations and Packaging certainly needs industrial automation on a larger scale. Some of the key challenges with many of these can be described as under:

1. Shortage of Skilled Manpower: Churning of Operators and labors is one of the biggest problems of many industries today. Due to the high turnover, organizations needs to frequently recruit and train new talent from the competitive market. This is time consuming, as well as, causes severe losses to the overall throughput and finished product supply chain.

2. Growing complexities in the manufacturing processes: With growing demands from the global clients, as well as, with the mandates from various stringent guidelines and certifications (viz. US-FDA, cGMP, OSHA, CE Certification, 21 CFR Ch-11 compliance and so on), the manufacturing operations have become highly niche and may not be possible with purely human based operating procedures.

3. Demanding Quality Standards by the Clients: With the ongoing trend of continuous improvement, all the standard guidelines and guiding bodies (viz. US-FDA, EU, cGMP, OSHA, CE Certification, 21 CFR Ch-11 compliance etc) demand better than the best of the quality results, which may not be always possible with manual operations.

4. Occasional mistakes leading to financial losses: Handling huge volumes of masses while strictly adhering to the schedules does lead to mistakes during manual handling. At times these can create a snowball effect resulting into very big financial impact.

5. Possibilities of operations hazards and accidents: Dealing with multiple hazardous chemicals simultaneously (that too in volumes), as well as, cumbersome mechanical operations can lead to human errors or mistakes resulting into causalities or fatalities too.

6. Too many compliances to meet: Manufacturing sectors need to meet too many compliances including Quality, Safety, Pollution, various audits etc. Managing all this with the targeted throughput is too challenging and can lead to human errors.

HOW CAN AUTOMATION SOLVE THE PROBLEM:

Automation (in layman's terms) can be defined as those set of automatic actions (executed by mechanical instruments Or equipments) which replaces the manual actions, thereby consistently delivers similar or superior results. It doesn't matter how complex the situation is, as well as, how big is the quantum of work to be done by automation. Some objectives advantages are as under:

1. Shortage of Skilled Manpower:

a. Automation can replace the manual work either partly Or fully.

b. With Automation, we can train the new joinees, as well as, conduct refresher trainings for the existing manpower.

c. With Automation, the operators can work remotely too (example, PLC or DCS operated unmanned actions)

2. Growing complexities in the manufacturing processes:

a. Programming as per 21 CFR Part 11 standards can allow manufacturing units to have total control over all the activities including possibility of tracking mistakes and errors.

b. Failures of instruments, mechanical parts or chemical parameters etc, as well as, deviations caused due to such failures can be easily and effectively tracked.

c. Consistency and the quality of the output can be assured and predicted with high accuracy.

3. Demanding Quality Standards by the Clients:

a. Audits of processes and past records can be effectively maintained thereby ensuring data for TQM is always up to date.

b. Electronic records can be maintained for a very long timespan and can be used for educating the software which controls key steps or actions involved in various stages of the manufacturing.

c. Failures or possibilities of failures are effectively auto-detected well in advance, thereby supporting and strengthening the preventive maintenance processes.

4. Occasional mistakes leading to financial losses:

a. With Automation, we can make the systems fool-proof, thereby, eliminating the possibilities of making a mistake.

b. QAP (Quality Assurance Plan) and stagewise inspections can be mandated ensuring zero mistakes and zero opportunities of escaping the possibilities of making mistakes.

c. Areas of human limitations can be easily addressed by automation, thereby ensuring no or minimal financial losses.

5. Possibilities of operations hazards and accidents:

a. Automation can partly or fully replace human based actions, thereby mitigating the possibilities of accidents and hazards.

b. Any deviations in operating parameters (ex. temperature, pressure, saturation of Nitrogen and Oxygen gas etc) can be easily tracked by automation and preventive and/or corrective actions can be auto-initiated thereby mitigating the risks of hazards and accidents.

c. Concepts like 5Ss and CAPA (Corrective and Preventive Actions) can be mandated (through Automation) in the form of compliances, thereby boosting the workplace safety.

6. Too many compliances to meet:

a. With the possibilities of data tracking and data mining, many compliances (mandated by clients) can be easily executed.

b. Automated systems can integrate and maintain parameters that must be strictly complied with.

c. Deviations and Non-compliances can be auto-traced and corrective actions can be taken quickly and proactively.

Please contact for your specific needs of industrial automation (including AI based industrial automation).

LIMITATIONS OF ANFD (AGITATED NUTSCHE FILTER DRYER)

2025-01-22T15:46:00.005+05:30

PROBLEMS ASSOCIATED WITH THE ANFD (AGITATED NUTSCHE FILTER DRYER) USED IN PHARMACEUTICAL, CHEMICAL, AGROCHEMICAL AND OTHER INDUSTRIES

ANF and ANFDs are widely used in the Industry majorly because of their superior filtration and drying performance in terms of filtration time, drying time, quality of the product and minimalistic utilization of the energy. However, there are a few limitations, which can hamper the overall productivity of a manufacturing plant or unit badly. Let's discuss them in brief.

DESCRIPTION OF THE TYPICAL OPERATIONAL STEPS IN ANF/ ANFDs:

In a typical scenario (rather in majority of the cases), an ANF or ANFD operates as per the following operational sequence viz.

1. Boot Cycle or Pressure Test Cycle: Here the ANF/ ANFD is pressurized by Air or Nitrogen gas to check if any of the valves or joints are leaking or not.

2. Charging or Feeding Cycle: The slurry type material (to be filtered and/or dried) is added to the ANF/ ANFD either manually or with the help of a flexible/rigid chute (gravity flow of the mass) or pumped in.

3. Filtration Cycle: The slurry fed to the ANF/ ANFD undergoes either Air/ Nitrogen gas pressure from the top Or vacuum from the bottom valve Or undergoes both simultaneously (pressure from the top and vacuum from the bottom) with an intent of expediting the filtration of the mass and thereby draining out the mother liquor as fast as possible.

4. Squeezing Or Pressing Cycle: The so called wet cake (formed after pressurized or vacuumized filtration as explained in the step above) is pressed with the help of the agitator by rotating it in the clockwise direction such that the blades touch the cake surface and gradually push the cake downwards while the agitator is in rotory motion (at a low rpm).

5. Washing Cycle: The cake formed after Filtration and Squeezing cycle many a times needs to be given a water-wash or a solvent-wash with an intent of diluting and removing impurities if any. For this purpose, a separate liquid (say water or solvent or any other liquid) is added to the cake from the top and the same sequence of charging-filtration-squeezing is repeated.

6. Mother Liquor Or Wash Liquid collection: It may be possible that the mother liquor (also referred to as ML) is of use to the businesses. Sometimes, ML contains major amount of solvent which can be recovered and re-used. ML is usually collected in tanks and vessel and can be stored or treated further as per the business requirements.

7. Cutting and/or Mixing Cycle: The wet cake (nicely squeezed and ready for drying) at times needs to be mixed well with an intent of increasing the cake volume so that the drying process can become more effective. The agitator is forcefully penetrated inside the cake while rotating it in the anti-clockwise direction at a low rpm.

8. Drying Cycle Or Vacuum Drying Cycle: The hot utility circulated in the limpet or jacket of the ANFD, as well as (optionally) in the agitator shaft and blades brings out the drying action in the ANFD. Under the desired vacuum (inside of the ANFD), the vapors generated are pulled and condensed inside of the shell and tube type heat exchanger and solvent or condensate is collected in a receiver tank in series.

9. Discharge Cycle: Majorly dried cake or dry powder is discharged from a dedicated nozzle (usually placed laterally on the shell of the ANFD).

10. Cleaning, CIP/ SIP and Changing of the Filter Cloth: As a part of operational sequence Or preventive maintenance, cleaning and changing of the filter cloth needs be carried our periodically.

LIMITATIONS ACCOCIATED WITH EACH OF THE OPERATIONAL STEPS (DISCUSSED ABOVE):

Typically the problems faced or limitations observed during ANF/ ANFD operations w.r.t. the operational sequence discussed above can be illustrated as follows:

1. Boot Cycle or Pressure Test Cycle:

# All valves needs to be closed and only the Air or Nitrogen valve needs to be open.

# There needs to be adequate pressure available in the header.

# No leakages (at any valve or instrument joint etc) are permitted.

# Since pressure needs to he held for a while (few mins to few hours as per operational SOP), it should be ensured that so much amount of pressure is available.

# Usually its a manual operation and consumes a lot of time.

2. Charging or Feeding Cycle:

# Usually charging is done from a reactor or a crystallizer, which produces and holds the volume of mass which is multiple times of the volume of that ANF/ ANFD. So, administering and charging the adequate amount of feed to the ANF/ ANFD is a challenge.

# At times, there is a complex network of the feeding headers and sub-headers (with multiple valves in series and parallel). Therefore, the next big challenge is to manually ensure the appropriate valves in the path needs to be open only (rest needs to be closed), so that the slurry follows the right path and reaches the right ANF/ ANFD. This is not only time consuming, but can be also highly tricky and complex. Also, role of the skilled operators becomes extremely important.

# Charging of multiple ANF/ ANFDs simultaneously can be extremely challenging.

# Doing all this while strictly adhering to the HAZOP guidelines can be too challenging and time consuming.

3. Filtration Cycle:

# Operator needs to visually monitor the changes in the physical appearance of the fed mass (which will gradually changes its form from slurry to wet cake) by physically seeing through the view-glass mounted on the top dish of the ANFD.

# Operator also needs to physically monitor ML flowing out of the ANF/ ANFD by keeping an eye on the view glass mounted on the ML outlet header.

# During the pressure-filtration, at times the top-most layer of the cake (slightly appearing to be a dry one) cracks forming V groove like cracks. The Nitrogen Or Air pressure easily flows out, thereby diluting the pressure-filtration effect. Operator needs to keep an eye of the crack formation and manually fill the cracks with the help of the agitator. This can be too frequent and too cumbersome.

# Operator needs to always ensure that appropriate valves only needs to be open and rest all are closed.

# Too much of the manual tasks and consumes a hell lot of time.

4. Squeezing Or Pressing Cycle:

# It's both a skill, as well as, an art where the operator needs to:

i) Decide first that he needs to start with the squeezing operation (i.e. agitator driven filtration operation)

ii) Move the agitator vertically downwards (by inching mechanism) on the surface of the cake, while the agitator is in clockwise rotations.

iii) If the cake is too soft, the agitator may get stuck inside the cake. Whereas, if the cake is hard, forceful movement of the agitator can damage the mechanical seal or cause deflection in the shaft.

# Operator also needs to physically monitor ML flowing out of the ANF/ ANFD by keeping an eye on the view glass mounted on the ML outlet header.

# Too much of the manual tasks and consumes a hell lot of time.

5. Washing Cycle:

# Problems associated with the Washing Cycle are somewhat similar to those associated with the Charging or Feeding cycle. In addition, the operator needs to ensure that the Wash Liquid is coming from the appropriate tank and in appropriate volume.

6. Mother Liquor Or Wash Liquid collection:

# Collection tanks can be separate for separate liquid washes (based on the SOP and process requirement) or can be a common tank.

# Operator needs to ensure the ML after wash is getting collected at the appropriate collection tank only.

# Incase there is a network of sub-headers of ML outlet line, appropriate valves should be aligned in the open position.

# Some mechanisms should be in place Or a visual alertness is needed to ensure the ML collection tank is not overflowing.

# Manual and cumbersome operation.

7. Cutting and/or Mixing Cycle:

# Movement of the agitator needs to be managed manually.

# Manual and cumbersome operation.

8. Drying Cycle Or Vacuum Drying Cycle:

# As per the Process (or SOP) the adequate temperature and vacuum conditions needs to be established. Operator needs to constantly monitor that.

# Drying end point needs to be defined (be it based on the end of the receipt of condensate or be it a sudden change in vacuum or something else).

# Skillful and manual operation

9. Discharge Cycle:

# At times, the discharge valve has a mechanical dead-plate (lock) at the end, which needs to be removed every time.

# Anti-clockwise movement of the agitator needs to be manually administered.

# Manual and cumbersome operation.

10. Cleaning, CIP/ SIP and Changing of the Filter Cloth:

# Purely manual and labor oriented operation.

CAN THESE CHALLENGES/ LIMITATIONS BE MITIGATED OR MINIMISED:

Industrial automation can be the only solution to these challenges. The level of automation depends on the complexities of the operations and the need of the process. The objective behind any of the automation should involve: 1. Ease of operations 2. Consistent Results 3. Optimization of the Process and 4. Reduction in the manual intervention (so as to get better accuracy of the outcome).

Please feel free to contact me at shg.techo@gmail.com for more information.

NAUTA MIXER DRYER (CONICAL MIXER DRYER)

2023-05-07T19:07:00.003+05:30

INTRODUCTION TO A NAUTA BLENDER or NAUTA MIXER:

NAUTA mixer Or blender refers to a popular industrial mixer which consist of a conical vessel (like a funnel) in which an inclined screw rotates in both planetary, as well as, in axial motion. Which means, the screw rotates along its own axis of rotation while taking a planetary along the internal wall of the mixer vessel.

The conical blender Or mixer Or Dryer is very popular among many manufacturing industries including Pharmaceutical, Nutraceutical, Dyes and Pigments, Food colors, Food items, Spices, Cosmetics and many more. Let is discuss it objectively, as well as, in comparative fashion (comparing with other popular industrial blenders such as Octagonal Blender, Double Cone Blender, V Blender, Vertical Conical Spiral Blender and Ribbon Blender.

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HISTORY OF NAUTA BLENDER or NAUTA MIXER:

The word NAUTA has nothing to do with Nautical Science Or Mariners Or Sailors. The word NAUTA is believed to have arrived from the legendary Mr. Johannes Ewardus Nauta (1890 - 1957), the founder of Nautamix company, who first started manufacturing of the conical mixer in 1939 in Netherlands. Soon the conical mixer NAUTA became very popular and got sold worldwide. Later Nautamix company got acquired by another giant engineering OEM and today few companies globally owns the trademark rights of "NAUTA". At the same time, many local engineering OEMs too are manufacturing the conical mixer without the name NAUTA, as they have studied and understood the technology.

(Drg Ref: V M Industries, Sarigam Gujrat)

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TYPES OF SOLID-SOLID MIXINGS:

Solid-Solid mixing (may it be in powder-powder Or granules mixing) is usually classified into four categories viz.

A. Convective Mixing:

Convective mixing essentially involves the movement of mass in bulk Or gross displacement of the mass which leads to mixing on a large level.

B. Shear Mixing:

Shearing action takes place due to sliding of a layer of powder or solid mass past another layer. Shear mixing may take longer than convective mixing, as the later appeals to the bigger volume of mass.

C. Diffusive Mixing:

The kind of mixing resulting from the random movement of particles within the mass is known as diffusive mixing, which results into more homogeneous mixture, however, can be a lot time consuming.

D. Chaotic Mixing:

The most irregularly patterned mixing, mostly resulting out of a random or undefined combination of convective and shear mixing is termed as chaotic Mixing.

NAUTA MIXER - ADVANTAGES AND APPLICATIONS:

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Conical Mixer (also known as the NAUTA Mixer) simultaneously generates local and rational convective mixing currents with the help of its axially rotating screw which also rotates in the planetary motion (along the inner wall of the cone), while its helical ribbon lifts the power mass to the top from the bottom of the cone.

While Horizontal Ribbon Blender, Vertical Conical Ribbon Blender and V Blender works on the principle of convective mixing, the Octagonal and Double Cone Blender follows the shear type mixing. When it comes to fine and homogeneous mixing, NAUTA is found to be the preferred choice, as the local convective currents gradually dominate the rational mixing currents resulting into more consistent and homogeneous mixing.

NAUTA mixers blenders are popularly used in many industries. In some cases, it is also used as a Mixer-Dryer, thereby removing the core moisture Or recovering the solvents.

MAJOR COMPONENTS OF THE NAUTA MIXER - BLENDER - DRYER:

1. Vertical Conical Shell (with Optional Limpet and Insulation) and the Top Dish: This vertical conical and optionally limpeted vessel is designed to handle desired volume of the mass with an optional provision of heating and vacuum (however, it is not mandatory). The limpet usually covers almost 80% of the height of the vessel. Incase it is limpeted, the conical vessel is also insulated with hot insulation material such as Mineral Wool Or Rock Wool and further cladded. The top dish is designed to take weight of the drive assembly, as well as, has a number of nozzles including the manhole.

2. Agitator Or Stirrer: A specially designed agitator majorly consist of two parts viz. a Rotary Arm and a Screw with helical ribbon on it.

Rotary Arm is connected to the vertical central shaft, which is driven by the central motor and gearbox at a low rpm. The objective of this Rotary Arm is to rotate along the central axis and thus carry the hanging screw along the inside wall of the cove (like a merry-go-round). At the same time, the hanging screw rotates along its own axis and is driven by a separate motor and gearbox. The shaft that drives this motion is passed through the hollow central shaft of the rotary arm. The complex gear arrangement ensures that both Rotary Arm and Screw rotates as per their desired orbital and axial path.

The Hanging Screw needs to be well balanced dynamically, as well as, passes through a suitable Mechanical Seal (fulfilling the vacuum and temperature requirements). As per the required torque calculations, both the AC frequency Motors and Gearboxes are designed. Suitable couplings may be provided inside the vessel, as well as, outside before gearbox in order to protect the drive assembly from damage due to rare case of jamming of screw. A soft starter along with VFD (variable frequency drive) is recommended to manage the torque.

3. Optional Vacuum Filter Assembly: Incase of a vacuumized operation, a vertical cylindrical filter housing mounted on the vacuum nozzle located on the top dish. The filtration assembly includes a course PP filter (say 10 to 20 micron) whose objective is to arrest the powder particles from going into the condenser Or vacuum pump along with the vapors.

4. Optional Chopper assembly Or Lump Breaker Assembly: A high speed chopping set of blades (rotating at around 200 to 300 rpm) mounted inside of the conical vessel (on the lateral surface) can be optionally provided with a gearbox and an AC frequency motor.

5. Optional Condenser: Typically a Shell and Tube Type Heat Exchanger is used to condense the vapors coming out of the Conical Dryer. Usually the process side fluid (vapors) are passed through tubes, whereas, on the Shell side the utility fluid (mostly chilled water Or cooling water) is circulated. However, it can be the other way around too (depending on the heat load calculations). Condenser can be insulated and cladded for avoiding heat loss to the ambience.

6. Optional Receiver: A solvent recovery receiver is provided at the bottom of the STHE condenser. Receiver can be either Vertical Cylindrical with legs supports Or Horizontal Cylindrical with saddle supports. A vacuum breaking arrangement is provided with a Control/ On-Off valve on the receiver.

7. Optional Vacuum Pump: A suitable capacity Vacuum Pump is connected to the system (mostly to the receiver), which creates vacuum inside the Conical Dryer, and, also facilitates the extraction of the vapors, hence complements the condensation process.

8. Optional Water Heating system Or Low Pressure Steam (for heating the Dryer, Shaft, Ribbon): Incase of a Hot Water System, a dedicated skid mounted vertical cylindrical vessel is provided with external heating i.e. either with steam (LPS) Or with Electrical Heaters. A circulation pump pushes the hot water into the Limpet, and the return water goes back into the Hot Water Generation tank. The level guage/switch on this tank ensure water doesn't spill over, and, make up water valves gets ON when level goes down. The Temperature sensor on the Hot Waters Tank, as well as, sensor on the Inlet of the Limpet coil together controls the flow of Steam (through PID control valve) Or the Electrical Heater, thus ensures the inlet water temperature stays in control. Incase of direct steam heating, the PID valve ensures steam is throttled and uniform temperature is maintained in the limpet.

9. CIP Or Spray Ball arrangement: Optionally, spray balls can be provided on the top dish of the conical shell, which can facilitate cleaning and washing of the main vessel post the batch operation is over.

10. Rotary Bottom Discharge Valve: The blended product is taken off from the bottom and is usually facilitated by the rotary discharge valve. A motorized rotary valve serves the purpose of uniform discharge flow without much wastages. In the rare case scenario, a knife gate valve Or a butterfly valve can also be used.

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MATERIAL OF CONSTRUCTION:

Incase of pharmaceutical Or food applications (where GMP validation is applicable) the Contact Parts are of SS316 Or Higher Grade, whereas, the Non Contact Parts are of SS304. Incase of Highly Corrosive chemicals, the Contact Parts are recommended to be of Hastelloy (C22 Or C276).

Incase of Non-GMP applications, both the contact and non contact parts can be SS304 Or MS based on the process requirement. Incase of Highly Corrosive chemicals, the Contact Parts can be Halar Coated Or PU Coated. The role of the process team becomes extremely important in these kind of decisions.

SURFACE FINISH:

In case of GMP setup, Product Contact surface is usually required to be of minimum 240 grit Mirror Finish and Non Contact surface is 180 grit matt finish.

AIR CLASSIFYING MILL V/S AIR JET MILL (MICRONIZER)

2023-03-26T04:46:00.000+05:30

INTRODUCTION TO AIR CLASSIFIER (AIR CLASSIFYING MILL):

Air Classifying Mill or ACM is one of the most popular size reduction equipment used in Chemical, Pharmaceutical, Cosmetics, Food, Polymer coatings and Metal power industries. As discussed in my earlier blogpost on Air Jet Mill, when the product is heat sensitive, as well as, needs fine grinding (say less than 5 micon to nano), Air Classifying Mill (ACM) is considered as one of the best options alongside with the Air Jet Mill (Micronizer). However, ACM is considered to be more versatile and stronger as compared to Air Jet Mill because of its ability to handle higher volumes of the material, can achieve more uniform micron size and can handle variety of materials including metal particles and other abrasive particles.

OPERATING PRINCIPLE:

In simple words, the Air Classifying Mill Or ACM works on a dual Or a combination principle viz. Impact Milling and Particle Classifying.

A high speed rotary disk with pins Or hammers mounted on it's surface (on its circumference) achieves the size reduction along with the surrounding stationary corrugated enclosure (just like the stator of a pulverizer). The particles upon impact and collision between the rotating hammers and stationary enclosure get reduced in size and gets pulled into the classifying mill by the drag force created by the turbulent air.

In the next stage, the particles that crossover the baffle wall covering the classifier are either classified to pass through Or are rejected back to the hammer section again based on the size and density of the particles.

(Pic Ref: www dot youtube dot com/watch?v=xlLSRM1N1e0)

HOW IT OPERATES (IN DETAIL DISCUSSION):

As discussed above, the Air Classifier mill (ACM) works on the principle of size reduction plus classification. As shown in the figure above, the milling disk and the classifier are two different parts which though are concentric, however, rotates as different speeds (rpm) and are operated by two different motors.

While eighty percent of the air enters the milling chamber through a tangential entry nozzle, the twenty percent air along with the powder mass (to be milled) enters through another tangential liner popularly known as 'product inlet liner'. The high rpm of the milling disk forces the powder particles to colloid with the corrugated wall of the milling chamber and with the hammers Or pins mounted on the milling disk. The hammers Or pins are rotating, whereas the corrugated wall of the milling chamber is stationary.

The particles thus reduced in size cross over the immediate next barrier wall and enters the classifier area. The classifier wheel has vertical cage like plates arranged such that the adequate size powder particles are able to enter the classifier wheel and bigger size particles are rejected back to the product baffle wall and further to milling disk hammer section. When the required size is too fine, the plates in the classifier are arranged at an angle with the center of the axis, thus making it difficult for the power particles to enter the classifier area. Those particles which qualify for the entry gets pushed out of the milling chamber from the central exhaust pipe towards the cyclone separator and finally gets collected into the product collection bin.

MAJOR COMPONENTS:

1. Milling Disk, its motor, pulley, bearing housing: The milling disk rotates at a very high speed. Hence. the horizontal disk with vertical hammers on it has a central shaft which is either directly connected with the high rpm AC motor Or is connected through a belt pulley. Bearings and seal plays an important role so as to avoid powder leakages.

2. Classifier Wheel, its motor, pulley, bearing housing: The classifier wheel too rotates at a very high speed, independent of the milling disk. The motor and central shaft of the classifier wheel can be either top mounted and protruding Or can be bottom mounted with 'shaft in shaft' arrangement. A variable frequency drive helps in varying the speed of the classifier as per the need. The vertical plates as well as the flanges etc are precisely machined for accurate results.

3. The milling chamber housing the milling disk, baffle wall and classifier: The milling chamber is made-up of a precisely machined modular metal basket. The outermost inner wall of the basket is threaded Or corrugated and appears like the corrugated wall of the pulverizer (stator part of the stator rotor assembly). The assembly is such that the milling disk rotates freely in the closed basket, however the gap between the two is extremely small and uniform.

The classifier wheel is many a times mounted into the top disk of the basket and a provision is made to open the top part of the basket along with its motor, seal and bearing housing from the hinged joint given between the top and bottom part of the milling chamber (basket). However that may not be possible in all cases.

The provision for high pressure inlet air, as well as, for air stream for getting the product mass in is made through two different liners.

4. Powder Feeder: A gravimetric feeder assembly is usually provided consisting of a feeder tank (usually vertical cylindrical with narrow bottom) along with a rotary valve that pushes out a metered quantity of the product into the pipe that carries the powder into the milling chamber under with the help of the moderately pressurized air stream.

5. Cyclone separator and Filter assembly unit: The product particles qualified by the classifier travels upwards with the high velocity air stream and enters the cyclone separator followed by the filtration chamber with fingerbags inside. At times, only a single cyclone separator is used with the finger bags hanging from the top which arrests the powder particles and allow the air to escape.

6. Product Collection Bag: The product collection bag Or basket is kept at the bottom of the cyclone separator and the filtration chamber (carrying finger bags).

7. External Air Filtration Unit (Optional): A series of bag filters including coarse filter (say upto 10 micron) followed by fine filter (say upto 3 micron) followed by a HEPA filter (say 0.3 micron) followed by a suction blower and its motor can be provided to treat the exhaust air before releasing it to the atmosphere.

8. Operating Panel: Operating panel can be either push button type Or can be with PLC and touch screen HMI.

APPLICATIONWISE ADVANTAGES OVER AIR JET MILL AND OTHER MILLING OPTIONS:

Some of the unique advantages that makes the ACM as the preferred choice over an Air Jet Mill, as well as other milling equipments are as under:

1. Output Volumes: ACM are far more faster than AJM, as milling and classification happens simultaneously on a larger scale.

2. Output Sizes: ACM is observed to be more effective incase of certain products over AJM and other milling equipments such as metal powders, abrasive products, polymerized products, highly fluppy products etc. Output size can be as low as nano, whereas, the feed material can be as big as a few millimeters. Such wide range of size reduction is not possible with Air Jet Milling in a single pass.

3. Gentle Handling and Milling of Heat Sensitive Products: ACM too yields size reduction without generation of much heat (just like AJM). This is one of the major reasons for choosing the ACM over other mechanical grinding equipments.

4. Easy Maintenance: The equipment isn't very complex, hence preventive maintenance is easy.

5. Economic and Long Lasting: ACMs are not very costly, at the same time do lasts for very long.

MOC OR MATERIAL OF CONSTRCTION:

Incase of GMP requirement, the product contact parts are chosen to be SS316 Or SS316L and non-contact parts are chosen to be of SS304. The hammers and other components of the milling chamber Or basket can be hardened also (depending on the material to be milled). PTFE Or PU liners can also be used incase of polymerized materials.

SIGMA MIXER (KNEADER MIXER) V/S PLOUGH SHEAR MIXER

2023-03-13T04:45:00.000+05:30

INTRODUCTION TO SIGMA (KNEADER) MIXER AND PLOUGH SHEAR MIXER:

Mixing of semisolid materials (especially if voluminous) can be challenging. Many a times, industries (especially food, polymers, resins, rubber and chemical manufacturing) require mixing of highly viscous, as well as, tough or dense materials. This require special mixers which are not only sturdy but also makes use of special type of agitators that can achieve the most efficient mixing. On the other hand, there are a few slurries which are soft but highly viscous and require the homogenization. In case of such type of materials also, special mixers are needed.

Sigma Or Kneader mixer is totally different from the Plough Shear Mixer in all aspects such as size, shape and utility. While the former is used for the breaking down and thorough mixing of the toughest semisolid lumpy mass, the later is used for mixing and homogenizing of the relatively softer lumpy slurries. Since the bulk densities of both kinds of materials would be different, the types of agitators too are very much different and unique.

SIGMA (KNEADER MIXER)

Plough Shear Mixer:

Plough Shear Mixer is a horizontal cylindrical drum type stationary mixer, where the mixing is achieved by the unique blades mounted on the concentric horizontal agitator. As mentioned in my other post on Vacuum Shovel Dryer, the ploughs of the mixer (because of their unique shape) not only breaks the lumps (if any), but continuously keeps lifting and pushing the mass out towards the inner cylindrical wall of the the drum). This continuous action at a high RPM initiates the mechanical fluidization of the material to be mixed. Based of the factors like the size and shape of the ploughs, distance between the adjacent ploughs and the RPM of the horizontal agitator, a centrifugal vortex motion takes place and hence the mixing mass starts getting thrown in all directions. This effect brings out a through mixing of the material (especially all the particles of different sizes and bulk densities).

Sigma Or Kneader Mixer:

Sigma Or Kneader Mixer is a horizontal (with body partially hemispherical drum shaped and partially rectangular shaped) type mixer, with specially designed low rpm twin blades (parallel blades) which can be either of overlapping nature Or are of tangentially scraping nature with respect to each other. The most popular types of blades can be S type, Z shaped or Profiled ones. However, the twisted S and Twisted Z types are common too. The sigma mixer with tangential type blades usually has one blade rotating at double the speed of the other. Whereas, the overalapping types blades has same rpm in both the blades, ensuring their orientation is such that they do not colloid with each other, however, does cover the maximum volume of the mixer.

Major Components of the Mixers:

1. Mixer Drum Or Bowl: As discussed above, both the mixers are absolutely different from each other, hence their mixing drums are also different in size, shape etc. Plough Shear mixer consists of a horizontal cylindrical stationary drum, which has the concentric agitator shaft (meaning parallel to the horizontal). Whereas, the Sigma Or Kneader Mixer has a specially designed drum which appears like a rectangle from the top, whereas, has a hemispherical bottom Or two halves which are hemispherical in nature. Here too both the blades are parallel to the horizontal.

Bowls in both the cases may be jacketed also (incase heating Or cooling is needed during mixing).

2. Agitator and Blades: Incase of a Plough Shear Mixer is a single hollow shaft with hollow branches welded Or bolted to the main shaft and the specially designed shovels Or ploughs are welded at the end of each branch. The entire unit ie central agitator along with the branches and ploughs rotate in one direction only (clockwise Or anticlockwise). Incase of the Sigma Or Kneader Mixer, usually have two shafts with solid machined Or profiled-cut heavy duty blades (either S type Or Z type Or some other profile). If one rotates clockwise, the other rotates anticlockwise, such that each blade pushes the mixing mass to the other blade.

3. Seal Or Gland packing, Bearings, Couplings and Gearbox: The bearings are couplings in both types of mixers depends on the type of the shaft used (hollow Or solid), shaft diameter etc. Usually the glandrope packing is used instead of mechanical seal, as it is more sturdy and long lasting. The gearboxes can be two in numbers incase of Sigma Mixer (one of each blade) Or can be one (with external gears for maintaining ration of 1:2 between the rpm of both the blades). However, incase of the Plough Shear Mixer, just a single gearbox suffices.

4. Motors: AC frequency motors of suitable capacity (based on the size of the mixer, torque calculations based on the properties of the mass to be mixed and the ratio of the gearbox) with a variable frequency drive are chosen. Sigma Mixer may use two separate motors for two different blades, whereas, Plough Shear Mixer does use only one motor.

5. Bottom Discharge Valve: Depending on the requirement, the bototm discharge valve can be of either flush type ball valve Or knife gate valve Or some other valve. Most of the times, the sigma mixer come with the bowl tilting mechanism, where the entire assembly (bowl with agitators) can be tilted upto ninety degrees so as to unload the material from the charging end itself.

6. Support Or Stand: Plough Shear Mixer can be supported with a cantilever skirt Or legs supports, however, sigma mixers are mostly both side supported.

7. Panel: Just like the other mixers Or dryers, both Plough Shear Mixer, as well as, Sigma Mixer can come with either a relay based push button type operating panel Or seldom with PLC based HMI operated touch screen panel. PLC/HMI is not so common, as the indications and commands are not many (viz. Start, Stop, Emergency Stop etc).

Material of Construction:

Both Plough Shear Mixer, as well as, Sigma Or Kneader Mixer are more common in Chemical and Food industry than in Pharmaceuticals. Also, they are majorly used for mixing higher Or voluminous batches. Therefore, GMP compliance may Or may not be needed. The product contact parts can be SS316 Or higher grade and Non Contact parts can be SS304 Or Mild Steel with epoxy painted. The process may demand the contact parts to be hastelloy C22 Or C276 Or Stainless Steel coated with Halar Or PU Or PVDF.

Surface Finish:

In case of the GMP compliance, the product contact surface needs to be extremely smooth. This helps in preventing the surface corrosion due to electrolytic cell formation. Hence the Product Contact surface is no less than 240 grit Mirror Finish and Non Contact surface is 180 grit matt finish. Incase of a Non-GMP set up, if Mild Steel is used (for Product Non Contact in some cases), the surface is either epoxy painted Or coated with protective layer.

Please feel free to contact incase of any queries, questions Or suggestions on this Or any other topic at shg.techo@gmail.com

RVPD V/S VACUUM SHOVEL DRYER PART - 1 of 2

2023-02-24T02:03:00.004+05:30

INTRODUCTION TO RVPD and SHOVEL DRYER:

RVPD (Rotary Vacuum Paddle Dryer) as well as, Vacuum Shovel Dryer are two of the similar looking and commonly used industrial dryers (especially popular in manufacturing of Pharmaceutical, Chemical, Food and Polymer group Products), however, has a few uniqueness that differentiates them from each other. While both these types of industrial dryers consists of a horizontal agitator shaft with blades rotating insides a concentric cylindrical static drum, the type of arms (and blades at the end of each arm) attached to the shaft differentiates them both. Let's do a comparative study as it is one of the most common question I come across from many of my clients.

RVPD or RVD or ROTARY VACUUM PADDLE DRYER:

(Pic Ref: www dot bewltd dot com)

Rotary Vacuum Paddle Dryer (RVPD) is simply a stationary horizontal drum dryer, which shuffles the material (inside the drum) with the help of the concentric horizontal agitator (with its arms and paddles rotating around its longitudinal axis). The paddles are attached to the arms of the agitator (mostly bolted, however can be welded too). The paddles usually are set at an angle such that those pushes the material to be dried towards the center. So the orientation of the paddles between the center of the dryer and the driving arm is exactly opposite of those paddles which lie between center and the opposite end of the drum. This arrangement at a low RPM ensures the material gets continuously shuffled within the dryer ensuring high level of heat transfer and hence highly effective and fast drying.

Vacuum Shovel Dryer is almost similar in construction, except the arrangement of the shovels or ploughs. The shovels Or ploughs because of its unique shape not only breaks the lumps (if any), but also (and most importantly) lift the mass continuously while pushing it out towards the inner wall of the the drum). This continuous action at a high RPM initiates the mechanical fluidization of the material to be dried. Based of the factors like the size and shape of the shovel or plough, distance between the adjacent ploughs and the RPM, a centrifugal vortex motion takes place and hence the material to be dried starts getting thrown in all directions. This effect brings out a through mixing of the material (especially all the particles of different sizes and bulk densities), because of which high level of heat transfer takes place within the mass which expedites the process of drying in multiples.

Applications and Advantages:

Both RVPD and Vacuum Shovel Dryer are highly popular for Vaccum Drying of any lumpy, sticky and sensitive material where the material to be dried has inherent moisture Or solvent to be removed. Many a times the material to be dried not only needs to be effectively dried, but also the color Or texture of the material needs to be maintained even at a higher temperature. Shovel Dryers are preferred over RVPD only when the material has a tendency of hard lump formation and/or the RPM required isnhigher.

Construction and Major Components:

1. Horizontal Drum: The Horizontal Cylindrical Jacketed/Limpeted Drum Or Vessel is basically designed for high vacuum, as well as for moderate pressure at high temperature. At the drive end, a mechanical seal is usually used to ensure there are no leakages from the drive end side. The other end Or non-drive end of the horizontal drum Or vessel is either cantelever Or is supported with skirt Or Legs. The drum Or vessel is either limpeted Or jacketed with a provision of the circulation of hot water Or low pressure steam. Thermic fluid can be an option too (depending on what is the desired drying temperature and what temperature difference (delta T) we want to achieve. The other end of the vessel is mostly sealed with a concentric round end plate (either clamped with a hinged joint Or is bolted to the body flange).

2. Shaft and Blades: As discussed above, the most important differentiating factor between RVPD and Vacuum Shovel Dryer is the types of blades used on the central horizontal hollow shaft agitator. Usually, the shaft and sub-arms of the shaft are also jacketed (ie Heating & Cooling fluid can be circulated in the agitator and arms). Blades are usually bolted to the arms of agitator. This is so because blades corrodes much faster than the agitator shaft and arms.

3. Bottom discharge of the material: The material to be dried is removed from the bottom valve (either a flush bottom valve Or a knife gate valve). Most of the times the preferred valve is zero holdup valve Or Flush Bottom Valve. At the same time, Knife Gate Valve Or Butterfly Valve are also not very uncommon. Except, the hold up volume is high incase of Knife as well as Butterfly valve.

4. Material Charging Nozzle: The suitable size material feed nozzle (mostly with a removable hopper) is provided on the top of the horizontally installed drum Or vessel. Where feed is automatic (i.e. comes from say the upper floor reactor etc by gravity), the nozzle is a concealed one (i.e. the feed pipe coupled to it) by a TC or a Flanged joint.

5. Vacuum Nozzle and Vapor Filter: Just like the Material Charging Nozzle, the Vacuum Nozzle too is provided on the top of the vessel and mostly it is located in the center of the top of the horizontal drum. This nozzle is usually big in size (designed based on the vapor load expected) and a concentric vertical cylindrical container (mostly insulated and cladded) is installed which houses a single or series of filterbags (usually 5 to 10 microns). The objective of the filter housing is to arrest the powder particles flying away due to turbulent shuffling of the material inside the vessel and vacuum applied inside the vessel.

6. Concentric Vacuum Pipe, Condenser(s) and Receiver(s): The vacuumized heating of the feed material (as well as the solvent Or water content of the feed) results into vapor generation which needs to be condensed effectively. A shell and tube heat exchanger is usually preferred along with either a vertical Or a horizontal cylindrical receiver (solvent collector pot). The cooling media used is either chilled water Or cooling water. The sizing of the condenser (Heat Transfer Area calculation) is done based on the Heat Load expected from the dying operation (based on the stoichiometry of the feed material).

7. Vacuum Pump and Vacuum Connection: Whenever the batches of drying material are not very big, the vacuum pumps can be either water ring pump Or oil seal pumps. Mostly water ring pumps are preferred as they are economical (not very expensive). However, incase of high vacuum requirement, oilseal pumps Or screw pumps are preferred.

8. Drive Assembly including Gearbox and AC Motor with VFD: A 3 phase heavy-duty AC motor (selected based on the torque calculations) is used along with the variable frequency drive. A suitable gearbox is used to achieve the desired rotational speed. Incase (especially applicable in Pharma) the drive is not needed in cleanroom or production room, the agitator shaft is taken long enough and is passed through the dividing wall. In such cases, a mechanical seal or a good quality glandrope is used in the hole of the wall ensuring the drum is fully inside the production room Or clean room (if applicable), whereas, the drive assembly (motor, gearbox etc) are outside of the room wall.

9. Operating Panel and Control Panel: The operating panel can be either a PLC driven Touch Screen HMI based Panel Or would be a push-button type relay based simple Panel. The control panel is basically for housing the controls such as VFDs and circuit breakers. Control panels are mostly kept in the non-production area Or some designated area (or in utility section area).

10. Water Heating and Circulation System Vs Low pressure steam: Whenever the drying temperature is not very high, the heating media preferred is either Hot Water or Low Pressure steam. Incase of Hot Water, a separate tank is taken with water inlet and outlet connection. This cylindrical tank (usually skid mounted) has either in-tank electric heater or intank heating coil carrying low pressure steam inside. A centrifugal pump is used to circulate the water constantly to the dryer jacket Or limpet. The set point of the temperature controller in the jacket of the dryer vessel is used to throttle the flow of steam through PID or cut off the electric heater (depending on what is used as a heating media).

The operating panel can be either a PLC driven Touch Screen HMI based Panel Or would be push-button type relay based simple Panel. The control panel is basically for hosing the controls such as VFDs and circuit breakers. Control panels are mostly kept in the non-production area Or some designated area (or in utility section area).

Material of Construction:

Depending on FDA Or any other governing body's guidelines and/or Need of the Procee, all Contact Parts can be SS316 Or Higher Grade, and Non Contact Parts can be SS304 (Or Mild Steel in case of Non-GMP set up). Incase of Highly Corrosive chemicals, the Contact Parts are recommended to be Hastelloy (C22 Or C276), Or Halar Coated SS304 Or PU Coated SS304 for both RVPD and Vacuum Shovel Dryer.

Surface Finish:

As per GMP (Good Manufacturing Practice) guidelines, the product contact surface needs to be extremely smooth. This helps in preventing the surface corrosion due to electrolytic cell formation. Hence the Product Contact surface is no less than 240 grit Mirror Finish and Non Contact surface is 180 grit matt finish. Incase of a Non-GMP set up, if Mild Steel is used (for Product Non Contact in some cases), the surface is either epoxy painted Or coated with protective layer.

Let us discuss the design and other need based considerations that goes into planning and designing an RVPD and a Vacuum Shovel dryer in PART -II of this post. Meanwhile, please feel free to contact incase of any queries, questions Or suggestions on this Or any other topic at shg.techo@gmail.com

LAB SCALE ANFD (Table Top Model/ R & D Model)

2022-08-07T20:12:00.005+05:30

LAB SCALE ANFD (AGITATED NUTSCHE FILTER DRYER):

Just like a Commercial Scale ANFD, the Lab Scale ANFD too is popular in Pharmaceutical and Chemical Laboratories and/or R& D Units. Many a times the API Or chemical substances under R&D are highly expensive. Taking trial batches with such expensive material on a commercial scale is too risky and expensive. Hence, the Lab Scale Units Or Pilot Plant units of such equipments becomes extremely convenient and economic.

(Pic Ref: Drawing made by myself)

WORKING PRINCPLE OF LAB SCALE ANFD:

The working principal of the Lab Scale ANFD is same as that of the commercial class ANFD, where the moisture Or solvent is removed by a series of Unit Operations viz. Filtration and Vacuum Drying.

Lab Model too consists of a small size jacketed/ limpeted vertical cylindrical stirred tank vessel (somewhat looking like a pressure vessel), which has its shell divided into two halves viz. Main Shell and Bottom Shell. A small mesh Or sieve separates the two halves. A filter cloth (mostly PP or some other membrane like material) covers the sieve. The excess water Or solvent from the wet mass is filtered through the mesh and is collected in the bottom shell, whereas, the remaining part of the water Or solvent is removed by evaporating it (through a heating action) and vacuum drying the wet mass.

In short, the solvent Or water to be removed, is separated and collected at two different places viz.

1. Bottom Shell: through mechanical filtration facilitated by:

(a) Air/ Inert Gas Pressure in the main shell Or

(b) Agitation created by the vertically adjustable specially designed Agitator Or

2. Vacuum Trap Or Receiver: by means of condensation of solvent/water vapors generated inside the main shell.

MAJOR COMPONENTS OF A LAB SCALE ANFD:

ANFD is basically is an integrated system consisting of various components as listed below:

1. Main Shell: This small size vertical cylindrical and Jacketed/ Limpeted vessel is usually constructed larger in diameter and smaller in height. This is so because bigger is the diameter of the vessel, more is the filtration area, and hence, faster is the filtration. The main shell is further insulated (and also cladded) with hot insulation material such as Mineral Wool Or Rock Wool.

2. Agitator Or Vertical Stirrer: An agitator is a low RPM (rotations per minute) stirrer, which is controlled by a Stepper Motor for precise movements of the agitator. Just like the commercial scale ANFD, this agitator too is designed to rotate both clockwise, as well as, anticlockwise. Either a Balls-Screw type arrangement Or a hydraulic cylinder is used to manage the vertical back and forth movement of the agitator. Agitator plays an extremely important role of sqeezing the wet cake, mother liquor wash, disturbing the cake and in overall filtration and drying.

3. Perforated Plate with Filter Cloth: The Main Shell and Bottom Shell are concentric and has the same diameter. A perforated mesh Or metal plate along with the filter cloth is sandwiched between the bottom flange of the main shell and top flange of the bottom shell. Basically this creates a filtration barrier between the two vessels.

4. Bottom Shell: The Bottom Shell is meant to collect the filtrate generated our of squeezing action of the cake. This squeezing action can be either because of the pressure generated by the agitator blades, Or because of the air/ neutral gas pressure generated above the cake surface Or seldom because of the vacuumized pull generated from the bottom shell i.e. from the bottom of the filter cloth.

5. Top Dish with Motor, Gear Box, Mechanical Seal, and Hydraulic Cylinders/ Ball Screw action: The most difficult and challenging part in the entire assembly of Lab Scale ANFD is to design the Top Dish. It is so because, it has to have space allocation for multiple nozzles and opening including agitator shaft and mechanical seal, feeding nozzle, handhole (if separate), vacuum nozzle, light glass, sight glass, instrumentation nozzles like Compound Gauge, Temperature Guage (if demanded by client) etc.

Therefore, this torrispherical dish is designed to handle pressure, vacuum and the weight of the complete drive assembly. A single-dry mechanical seal is used to arrest vacuum Or pressure inside the main shell and top dish. Good quality gasket (either food grade silicon Or Viton Or at times PTFE) is used between the flanges of the top dish and main shell. Since it is a small assembly, even a ball-screw kind of an arrangement can be preferable over a hydraulic cylinder for vertical movement of the agitator. Motor is programmable (stepper motor) which ensure highly precise movements.

6. Cake Discharge: Since the entire assembly is small, the dry cake can be manually taken off the main shell by dismantling it and tilting it easily.

7. Condenser: A Shell and Tube Type Heat Exchanger (mostly Vertical one) is used to condense the hot vapors generated inside of the main shell. Usually the process side fluid (vapors) are passed through tubes, whereas, on the Shell side the utility fluid (mostly chilled water Or cooling water) is circulated. However, it can be the other way around too (depending on the heat load calculations). Condenser can be insulated and cladded for avoiding heat loss to the ambience.

8. Receiver: Ideally a receiver is used to collect the condensate from the condenser. However, in many cases, it is also used to collect the filtrate from the bottom shell of an ANFD. In such situations, the Receiver is arranged either below the bottom shell of ANFD Or below the STHE type Condenser, and a pipe manifold with check valves is provided for ensuring both condensate and filtrate can be collected in the receiver. A vacuum breaking arrangement needs to be provided with a Control/ On-Off valve on the receiver, so that the condensate can be feeded to the receiver without breaking the vacuum.

9. Common Skid: A metal skid is provided to support the entire assembly including the ANFD, assembly for Lifting and Lowering of the Agitator, Condenser, Receiver, Vacuum pump, Water Heating system (if available) and Operating Panel.

10. Vacuum Pump: A suitable capacity Vacuum Pump is connected to the system (mostly to the receiver), which creates vacuum inside the ANFD, and, also facilitates the extraction of the vapors, hence complements the condensation process.

10. Water Heating system Or Low Pressure Steam (for heating the ANFD main shell Limpet): Incase of a Hot Water System, a separate vertical cylindrical vessel is provided with external heating i.e. either with steam (LPS) Or with Electrical Heaters. A circulation pump pushes the hot water into the Limpet/Jacket of the ANFD Main Shell, and the return water goes back into the Hot Water Generation tank. The level guage/switch on this tank ensure water doesn't spill over, and, make up water valves gets ON when level goes down. The Temperature sensor on the Hot Waters Tank, as well as, sensor on the Inlet of the Limpet coil together controls the flow of Steam (through PID control valve) Or the Electrical Heater, thus ensures the inlet water temperature stays in control.

Incase of Direct Steam (LPS) Heating, the PID valve ensures steam is throttled and uniform temperature is maintained in the limpet/ Jacket of the ANFD's Main Shell.,

11. Nitrogen Purging system/ Air Pressure system: A nozzle can be provided with control valve, that can facilitate the intermediate and periodic gushing or N2 gas, which pushes the vapors out towards the condenser. Same nozzle can be used for providing the Air Pressure to facilitate the filtration operation. Its important to note here that the Vacuum needs to be stopped temporarily while purging.

TYPICAL SEQUENCE OF OPERATIONS IN ANFD:

A general sequence of operation can be described as per below. It is to be noted that the number of steps, sequence and other protocol can very from company to company and based on the product and most importantly the SOP.

STEP -1 FILTRATION: The wet mass before drying has to undergo filtration first. In this step, either Air Or Nitrogen pressure is applied to the main chamber Or Vacuum is applied to the bottom shell Or both of these done. The excess water or solvent it thus pushed and pulled to pass through the filter cloth. Heating may Or may not be needed in this case. However, the rotating agitator helps in pushing the material down towards the filter media.

STEP -2 SOLVENT/ WATER/ MOTHER LIQUOR WASH: Sometimes the process demands Process Water/ Solvent wash Or Mother Liquor wash to the wet cake. This action (Filtration - ML Wash- Filtration) may be repeated a number of times depending on the process. The agitator is pulled up with the hydraulic cylinder and after adding water/ML, it is taken down with opposite direction rotation which disturbs the settled cake and facilitate proper washing of the cake.

STEP -3 HEATING AND VACUUM DRYING: When the cake is well filtered (or filtered as per SOP), heating is carried under vacuum by circulating the hot utility in the limpet of the main shell. As per the process requirement, as well as SOP, the drying cycle can be repeated Or extended based on the in batch sampling results.

STEP -4 SOLVENT OR ML (MOTHER LIQUOR) COLLECTION: As mentioned earlier, the solvent or ML can be collected in both bottom shell, as well as, in the receiver.

STEP -5 DISCHARGING OF THE DRIED CAKE: When the cake is dried upto expectations, the vacuum is broken and the cake is manually taken out (since it's a small size assembly, hence side discharge valve is not needed).

MATERIAL OF CONSTRUCTION:

Usually the Contact Parts are SS316 Or Higher Grade, and Non Contact Parts are SS304. This is to meet the GMP guidelines (followed by Pharma, Food and Cosmetics largely). The Non - Contact can be chosen to be of Mild Steel in case of Non-GMP set up. Incase of Highly Corrosive chemicals, it is highly recommended that the Contact Parts are of Hastelloy (C22 Or C276), Or Halar Coated SS304 Or PU/ PFA Coated SS304. Mostly the Metal Sieve is either SS316 Or Hastelloy and is covered with PP filter cloth.

SURFACE FINISH:

As per the GMP (Good Manufacturing Practice) guidelines, the product contact surface needs to be extremely smooth. This also helps in preventing the surface corrosion due to electrolytic cell formation. Hence the Product Contact Surface usually is minimum 240 grit Mirror Finish and Non Contact Surface is 180 grit matt finish. Incase of a Non-GMP set up, if Mild Steel is used (for Product Non Contact in some cases), the surface is either epoxy painted Or coated with protective layer.

Watchout for the Next Blog Post on Lab Scale ANFD with Rigid Isolator (Integration with Containment Solution).

Also, please do visit my earlier blog post on Commercial Scale ANFD

Please feel free to write back at shg.techo@gmail.com incase of questions, queries Or any sort of additional assistance needed on Design, Sales, Qualification or other aspects.

Don't forget to subscribe to this Blog.

MULTIMILL V/S CO-MILL

2022-07-31T03:33:00.007+05:30

INTRODUCTION TO AN MULTI-MILL and CONE MILL (CO-MILL):

Both Multi-mill and Cone-mill are widely used as Size Reduction equipments, not just in Pharmaceutical Or Nutraceuticals Or Herbal medicine production, but also in Food and Chemicals manufacturing plants. In fact, some of the most popularly observed equipments used in manufacturing organizations include Multimills, Co-Mills and Vibrosifters.

We have discussed in the earlier blogpost (Micronizer/Air Jet Mill) that yield of a chemical reaction or bonding between two molecules becomes better when the particles of the participating material are of smaller and uniform size. Therefore, whether it is the dried API or Flakes Or at times even the Granules obtained from the Granulator are taken for Multimilling Or Co-Milling.

(Pic Ref: www dot jicon dot com).

COMPARATIVE STUDY BETWEEN A MULTI-MILL and A CONE MILL (CO-MILL):

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Both Multimill and Co-Mill are often used for coarse milling. Which means, unlike the Micronizer (or AJM), Multimill or Co-Mill can yield the coarse (not so fine) material with an average size of not lesser than 500 microns Or 500 micrometers (35 mesh). However, there are a few specifics of both these equipments, which decides their preference over others, and can be listed as under:

# Multimills are used for size reduction by chopping, shredding, hammering and pulverizing. Whereas, Cone-Mill Or Co-mills are slightly gentle on the material to be grinded.

# Multimill has a set of static and high speed rotating blades and hammers. Co-Mill has a pair of blades in a V shape that simply pushes the material on the peripheral V shaped mesh.

# Since the blades and hammers in a Multimill are designed to cover a specific sweep diamater, the outer Or peripheral mesh Or screen is vertical cylindrical in nature. Whereas, incase of a Co-Mill, the outer screen Or mesh is in a V shaped Cap, as the blades are fabricated to form a V (as shown in the pic above).

# Multimill can handle slightly hard, wet and lumpy materials also, whereas, Co-Mills are advised to be used with dry and not extremely hard materials. Otherwise, there can be chances of chocking of the mesh.

GMP COMPLIANCE OF MULTI-MILL and CONE MILL (CO-MILL):

Both Multimill and Co-Mill can be totally GMP/ cGMP compliant. Because of their simple and economic construction, they are usually made out of corrosion resistant material viz. SS316 for contact parts and SS304 or equivalent material for Non Contact Parts. If need be, the superior materials such as Hastelloy C22 Or C 276 can also be selected.

OTHER ADVANTAGES OF MULTI-MILL and CONE MILL (CO-MILL):

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# Simple Construction: Both these equipments has a set of blades mounted on a central shaft which is directly (or in some cases through a pully drive) attached to an AC Motor. The blades assembly is covered with a pot made out of a mesh or screen which retains the larger size particles and allows the smaller size particles to pass through. The entire assembly along with the drive is supported by a metal stand with castor wheels for easy movement. All these features make both these equipments user friendly.

# Low Cost: Unless constructed with corrosion resistant material like Hastelloy C22 Or C276, both Multimill and Co-Mill are extremely economic, hence are usually purchased by manufacturing units even when their need is not so urgent.

# Possibility of automation: If need be, both Multimill and Co-Mill can be operated through an HMI-PLC. Both these can be integrated in an assembly line and can be automated viz. milling after granulation followed by sieving, Or milling followed by micronizer followed by packaging etc.

# Flameproof Construction: A flameproof motor can be used if need be and so can be the operating and control panel.

# Mobility, Lightweight and Less Floorspace utilization: Both Multimill and Co-Mill comes with a stand with castor wheels and hence can be relocated as and when needed. Both of them are vertically designed and hence requires minimum floor space.

# Low Maintenance: Because of the simple constructions, the chances of breakdown and occasions of maintenance are minimum.

CHALLENGES WITH MULTI-MILL and CONE MILL (CO-MILL):

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Usually the challenging instances with Multimill and Cone-Mill are associated more with the nature of the material handled than the equipment itself. Some of the common challenges can be listed as under:

# Frequent Choking of the Mesh/ Jamming of the Blades: This can take place at times and is usually linked with a particular type of material to be grinded. There could be various reasons behind chocking such as mesh being too fine (say less than 500 micron), material being sticky Or hygroscopic in nature, Or material is too hard etc.

# Material Getting Hot Or Temperature of the output material going much higher than the feed material: This is usually associated with motor consuming more current. The most common reason behind this would be the resistance offered by the material to the blades. This may be because of overloading the equipment (by the user) with the feed material or because of the reasons discussed in earlier point.

# Equipment making strange and loud noise: If the material is overloaded or offering too much resistance to the rotating parts, chances are that they may create a loud noise. There can be chances of friction between some of the metal parts Or wear & tear of some of the parts.

# CIP or SIP incase of integration in Containment Zone: Sometimes milling equipments needs to be integrated in an Isolator along with other equipments. In such cases cleaning and washing of the equipments can become bit of a challenge.

PART - 2 of 2: PHARMACEUTICAL CAPSULES BASICS AND ENCAPSULATION PROCESS

2022-07-23T22:12:00.003+05:30

AUTOMATIC AND SEMI-AUTOMATIC CAPSULE FILLING MACHINES:

As discussed in the previous post, i.e. in Part - 1 of 2, the process of Hard Gelatin Capsule Filling essentially requires a series of actions viz:

a. Empty Capsules loading into the Loading Hopper

b. Rectification of the Capsules i.e. orientation of the capsules in such a way that body faces downwards (towards the ground) and cap faces upwards (towards the sky).

c. Separation of the Cap from the Body

d. Loading the powder (or active ingredients) feed material into its feeder

e. Slug formation of the feed material

f. Dosing the slug formed into the capsule

g. Placing the Cap back on the Body of the capsule, and thus locking them together.

h. Polishing and Sorting of the capsules (optional)

i. Ejection of the filled capsules from the system (incase of any automatic system)

AUTOMATIC VS SEMI-AUTOMATIC CAPSULE FILLING MACHINES:

The series of actions discussed above, if are arranged to take place in a synchronized manner, then the facilitating equipment is known as an Automatic Encapsulation Machine.

However, in a Semi Automatic machine, some of these activities require manual intervention. A Semi Automatic Machine is more closer to a Manual Capsule Filling machine than Automatic one. In the Semi Automatic one, the Capsule Rectification is automatic. Similarly, the slug formation and capsule feeding is automatic. Finally, after matching top and bottom plates, the action of sealing the body with cap is automatic. Overall, the efficiency is very low, as, almost 70% percent activities are to be performed manually.

On an average, the output of the Semi Automatic machine could be in the range of 15,000 to 25,000 capsules per hour, whereas, that of a Manual machine could be upto 15,000 capsules/ hr. The Fully Automatic Capsule Filling can have an output as high as 150,000 capsules/ hr Or may be even more.

AUTOMATIC CAPSULE FILLING MACHINE IN DETAILS:

(Video Ref: www dot jicon dot com)

1. Capsule Feeder and the Process of Rectification: The Feeder Hopper is loaded with the empty capsules manually. The capsules eventually fall into a vertical cage like structure and forms a vertical array, where, a back and forth reciprocating plate pushes them ensuring the capsules are oriented in one direction only ie. Cap upwards and Body downwards.

(Pic Ref: www dot jicon dot com)

2. Separation of the Cap from the Body: The Rectified Capsules are further ejected into the upper part of the Turret. A low vacuum (generated by the vacuum pump) creates a pulling force, which resists and holds back the body part of the capsules, as those are engaged with the lower portion of the rotating Turret plate, which has a rotary indexing motion and thus keep transporting the capsules from one station to other station.

3. Powder Feeding and eventually Capsule Filling: The feed material Or powder is fed to the hopper (mostly manually Or with the help of some powder transfer mechanism). The feed material is further driven to the tamping assembly with the help of a screw type agitator Or auger. The temping assembly consist of serval sets of reciprocating tamping pins and dosing discs which are rotary indexed. These dosing discs has the small cavities where the powder sits and are compressed by the tamping pins progressively. The last set of the tamping assembly pushes the slug formed into the capsule body.

(Pic Ref: www dot jicon dot com)

4. Other forms of Ingredients Feeding into the Capsule Body: Apart from the powder, there can be other feeding material like Pellets Or Tablets etc. There are a few extra stations available on the main turret. The feeding mechanism is designed based on what to be fed, its nature, the size and diameter of the capsule body.

(Pic Ref: www dot jicon dot com)

5. Filled Capsules Ejection: The tamping pins pushes out the filled capsules towards the end of the rotation.

6. Filled Capsules Sorting, Polishing and Dust Collector: Separate attachments are provided each of the functions like capsule sorting, capsule polishing and dust collector.

MATERIAL OF CONSTRUCTION:

Contact Parts are SS316 Or Higher Grade, and Non Contact Parts are SS304.

SURFACE FINISH:

The Product Contact Surface usually is minimum 240 grit Mirror Finish and Non Contact Surface is 180 grit matt finish.

Please do go through the first part of the blog post, i.e. in Part 1 of 2 for basics of capsules and manual capsule filling machine.

Please feel free to write back at shg.techo@gmail.com incase of questions, queries Or any sort of additional assistance needed on Design, Sales, Qualification or other aspects.

PART - 1 of 2: PHARMACEUTICAL CAPSULES BASICS AND ENCAPSULATION PROCESS

2022-07-23T02:51:00.001+05:30

INTRODUCTION TO PHARMACEUTICAL CAPSULES:

Pharmaceutical Capsule is a versatile form of an oral solid dosage (second most popular after Tablet), which is easily consumable by humans. History indicates that capsule are invented to overcome the limitations and discomfort cased by the pharmaceutical tablets viz.

# Capsule shell can contain multiple or more than one forms of drugs including powder, granules, pellets etc, whereas, a Tablet is a solid form of a medicine.

# Capsules can act faster, as the outer shell simply dissolves in the digestive track and the medication or the active ingredients inside gets absorbed in the blood stream faster as compared to Tablets.

# Tablets can have flavored coatings, which can go away while consumption and thus can leave bad taste in mouth, whereas, capsules are tasteless.

# Some of the drugs (which are meant to be consumed orally) cannot be effectively made in the form of a Tablet, hence Capsule is the only available option for them.

TYPES AND SIZES OF CAPSULES:

Pharmaceutical Capsules are found to be of two types viz. Hard Gelatin (or Cellulose shell) Capsules and Softgel Capsules. The manufacturing process for Hard and Softgel are different, as their use is different. While Hard capsules can be used to fill drugs and active ingredients in the form of powder, pellets, tablets etc, the Softgel capsules are meant for carrying the appropriate dose of drugs and active ingredients in the form of a liquid inside.

In this post, we will focus on the Hard Gelatin capsules, which are manufactured in two parts viz body shell and cap. Later, with the help of encapsulation machine, the drugs are filled inside the capsule body and the cap is fitted back on the body shell thus sealing the drug inside.

Hard Gelatin Capsules used in Pharma Industry can be classified as under:

# Size 000: Average weight is 163 mg, with a tolerance of +/- 11 mg, and the gross volume is 1.37 ml

# Size 00: Average weight is 118 mg, with a tolerance of +/- 7 mg, and the gross volume is 0.91 ml

# Size 0: Average weight is 95 mg, with a tolerance of +/- 6 mg, and the gross volume is 0.68 ml

# Size 1: Average weight is 75 mg, with a tolerance of +/- 6 mg, and the gross volume is 0.5 ml

# Size 2: Average weight is 60 mg, with a tolerance of +/- 4 mg, and the gross volume is 0.37 ml

# Size 3: Average weight is 47 mg, with a tolerance of +/- 3 mg, and the gross volume is 0.3 ml

# Size 4: Average weight is 38 mg, with a tolerance of +/- 3 mg, and the gross volume is 0.21 ml

INTRODUCTION TO ENCAPSULATION (CAPSULE FILLING MACHINES):

Capsule filling machines can be classified as Manual, Automatic and Semi Automatic.

Encapsulation process overall essentially requires multiple action such as separating the cap from the body of the empty capsules, forming the proper and accurate slug of the feed (powder), feeding the slug in the capsule body, sealing the body with cap again and then de-dusting and cleaning if needed.

Based on the level of automation, the machine falls under either of these three categories.

MANUAL CAPSULE FILLING MACHINE:

A Manual Or Hand Operated Capsule filling machine is basically a made up of a punch type Stainless Steel structure. The capsule holding plate is made in two pars with concentric holes. Usually 300 holes machine is found to be the most common one. The 300 holes are machined in both these plates in the form of an array of 25 X 12.

The empty hard gelatin capsules are then fed to theses plates vertically and manually (such that one capsule occupies one hole). While feeding the capsules, one has to ensure that the capsule's body is facing ground and the cap is facing the sky.

A manual lever is applied, which pushes the top plate up and a gap is created between top and bottom plate. Now, the concentric holes between both these plates have a slightly different diameters. The low plate has a smaller diameter (same as the capsule body diameter), hence, the capsule bodies are held back by the lower plate, whereas, the top part of the capsule (cap) are taken away by the top plate during the lever action. The holes in the top plates are slightly bigger (same as the diameter of the cap of the capsule).

Once the top plate (with capsule caps) is removed manually, the actual powder feed is added or poured on the bottom plate and the powder is allowed to get inside and fill the capsule body. The operator manually (with the help of a metal plate) pushes and spreads the powder to get deposited in each capsule evenly and equally.

The main frame (where the bottom plate sits) has a hinged foldable arm which has an equal size plate at the end with pins on it. The utility of this arm with pinned plate is to push the material fed in the capsule bodies to get properly fed inside (and to fill the volume uniformly).

This hinged arm is then lifted again and the top plate (carrying capsule caps) is kept back on the filled capsule bodies for reunion. In order to ensure that both plates exactly coincides, there are guide-pins provided on the top plate that properly fits the bottom plates, hence, each capsule cap properly coincides with the respective capsule body.

In order to achieve the reunion of each capsule, the bottom frame is provided with one more hinged arm with a foldable plate. This plate when exercised, pushed the caps gently on the body and the telescopic nature of the cap and body ensure the capsules are sealed.

The foldable hinged plate is then lifted and once again the top plate is lifted with full capsules (body + cap + fed ingredients).

(Pic Ref: www dot jicon dot com)

MATERIAL OF CONSTRUCTION:

Since Pharmaceutical, Food and even Cosmetics follows GMP guidelines (sometimes due to statutory mandates), usually the Contact Parts are SS316 Or Higher Grade, and Non Contact Parts are SS304.

SURFACE FINISH:

In the next part of this blog post, i.e. in Part 2 of 2, we will discuss about Semi Automatic and Fully Automatic Capsule Filling Machine.

Meanwhile, please feel free to write back at shg.techo@gmail.com incase of questions, queries Or any sort of additional assistance needed on Design, Sales, Qualification or other aspects.

PART - 2 of 2 ROTOCONE VACUUM DRYER/ ROTARY CONE VACUUM DRYER/ DOUBLE CONE VACUUM DRYER (RCVD/ RVD/ DVD)

2022-07-15T01:08:00.004+05:30

INTRODUCTION TO PART - II OF ROTOCONE VACUUM DRYER/ ROTARY CONE VACUUM DRYER/ DOUBLE CONE VACUUM DRYER (RCVD/ RVD/ DVD)

In Part -I, we discussed about RCVD and its components in details. In this post i.e. Part - II, we will discuss about the need based considerations while designing and planning an RCVD.

(Pic Ref: www dot promasengineers dot com)

THE FACTORT THAT MAKES RCVD or RCVD or DVD SO POPULAR AND A PREFFERED CHOICE ARE AS UNDER:

1. Vacuum Drying under Moderate or Low Temperature:

RCVD bowl is provided with a metal jacket (usually SS304 grade in Pharma API) which allows the Hot Water or Low Pressure Steam (at usually 3 to 3.5 bar, Non IBR) to heat the surface and inturn heat the mass to be dried by conduction and convection. Because of the application of the vacuum inside the closed bowl, the vapor pressure inside the bowl drops and hence the boiling point of the liquid to be evaporated (viz. Water or Solvent) too drops and hence boiling takes place at lower temperature and vapor generation (and subsequently extraction of vapors) happens faster as compared to any other traditional drying method.

2. Material Shuffling for achieving Uniform Heat Transfer:

RCVD is provided with a rotary mechanism, wherein, the bowl rotates along a horizontal axis (it is supported over A or C shaped strong metal structures with bearings) at a low rpm (rotations per minute). Here the layer by layer shuffling of the mass inside the RCVD bowl takes place, resulting into uniform heat transfer amongst the wet powder particles. Most importantly, the powder mass shuffling takes place with minimum contact with any mechanical moving parts inside the RCVD bowl. All other vacuumized dryers works on either a complete static bed Or wet powder being shuffled by some mechanical agitator type structure. However, such structures needs to be cleaned thoroughly as per pharmaceutical standards and hence RCVD is preferred over other vacuumized dryers.

3. Vacuum Application, Inert Gas Purging and Temperature sensing through a smallest possible protrusion:

RCVD has a unique design in which a horizontal hollow pipe (which acts as a vacuum Or suction pipe) protrudes inside the RCVD bowl through a central smallest possible opening. The same pipe acts as a inert gas (usually nitrogen) purging nozzle (used to push the vapors). Further, a temperature sensing element is passed through this horizontal pipe, which, further tries to sense the temperature of the inside mass And/ Or vapors. In any other type of a vacuum dryer, managing all these things is too difficult as there is a risk of vacuum leakage.

4. Possibility of fully automatic loading and unloading of the mass:

It is one of the biggest concern of the Pharma, as well as, other industries today, to handle hazardous and polluting drugs Or chemicals, while ensuring Or following the safety standards. RCVD comes with a charging manhole, discharge butterfly valve and optional sampling valve, as well as, spray ball for cleaning in place (CIP/ WIP). The Charging and Discharging operation can be made completely automated.

CARE TO BE TAKEN WHILE DESIGNING AN RCVD:

1. Material of Construction: As mentioned above, the right MOC will decide the adherence to the quality and process parameters, as well as, longevity of the RCVD.

2. Level of Automation: Depending on the needs of the Production Department, as well as, budget allocation, the level of automation can be decided. Example, if product charging Or discharging is the prime need, the external Powder Transfer System can be integrated along with the RCVD and the bottom discharge valve can be pneumatically actuated.

3. Statutory and Safety compliance: Sometimes, due to company policy and FDA mandate, special features are incorporated such as Touch Screen HMI (Human Machine Interface) with PLC (Programmable Logic Control). In some cases, there can be further sophistication by adopting special Data Security measures such as 21 CFR Chapter 11 compliance, which allows password protected individualistic logins and maintains record of each activity by each user. Overall, Safety, GMP guidelines along with respective FDA mandates has to be followed while designing an RCVD.

4. Batch Size Calculations: A basic Process Calculations must be done followed by Thermodynamics Or Heat Load calculations. This helps in deciding the optimum batch size, as well as, the time cycle, hence monthly Or timely production throughput.

5. Available Floor Space, Availability of the Utilities and Floor Layout/ Elevation: Many a times, project team overlooks the area and space available and later have to regret the decision as RCVD doesn't fit in that size. Similarly, the utility equipments such as Hot Water Tank, Vacuum Pump, Chilled Or Cooling Water, Steam, Nitrogen and Electrical Panel etc if not planned favorably can cause a lot of trouble such as financial loss due to structural rearrangement work, major construction work and sometimes production time loss too. As a usual practice all these things are planned simultaneously and in sync with each other. Also, RCVD GAD (General Arrangement Drawing) is superimposed on Autocad Layout Drawing to see the feasibility of installation during design stage.

6. Thorough attention to the minute design aspects: Designing aspects such as Positioning of the Mechanical Seal, Spur-Pinion Geared Drive versus Direct Gearbox Drive system, Usual Vacuum Bulb with PP cloth bag versus Sintered Mesh Filterbag, CIP system (cleaning in place) by Spray Ball, In-Process Sampling, Nitrogen Purging, External Choppers/ Lump Breakers, Cantilevers Shaft versus Both side Supported Structure etc has to be given extremely detailed attention.

7. Product Specific Operational Challenges (based on the previous experience Or Studies): Since it is a capital purchase, the careful attention must be given to the specific needs of the Production Team, concerns and apprehensions of the Engineering and Maintenance, as well as, the Safety and Statutory department, which helps ensure the production goes smooth.

8. Mechanical and Process Design, as well as, Sizing of the Equipments: Stress analysis/ calculations must be done under varying parameters such as temperature, vacuum and pressure. Similarly, the thickness calculations must be done keeping in mind the static and dynamic loads. The important bought out items such as Motor, Gearbox, Seal, Valves etc should be designed as per the Industry Standards.

CASES OF RCVD FAILURE WITH ILLUSTRATIONS:

This topic is really vast and hence I will cover it through a separate blog.

Please do visit Part - I of the same post for understanding RCVD details.

Please feel free to contact me regarding any questions, queries Or additional assistance needed on Design, Sales, Qualification or other aspects at shg.techo@gmail.com

PART 1 OF 2: TABLET COATING, COATING PAN AND AUTOCOATER

2022-06-26T20:18:00.000+05:30

INTRODUCTION TO PHARMACEUTICAL TABLET COATING:

In our last post on Tablet Compression, we did discuss a brief history of Pharmaceutical Tablets. As you may be aware, the tablets and pills are said to exists for more than thirty five centuries, however, may not be in the exact Or similar shape of the tablets Or pills as we currently use. Also, one of the theory suggests that the first reference to medicinal pills was found in ancient Egypt. 'Katapotia' was the popular name used for such medicinal pills in ancient Greece, which indicated that those pills were prepared for swallowing purpose, so as to gain the medicinal benefits.

One can imagine that such pills Or tablets formed manually would certainly be of odd shape Or may be of much bigger in size as compared to today's tablets and pills. Therefore, it must have been extremely challenging to consume (swallow) those medicinal pills and tablets. Needless to mention that the efforts must have been made to make it easy to swallow and hence the concept of coating the tablets Or pills with an easy going, easy tasting Or soft-greasy type and non harmful material must have originated.

Today, with advancement of science and technology, we find tablets with precise shape and mass with various types of coatings that makes the consumption easy and enjoyable.

POPULAR REASONS BEHIND COATING THE PHARMACEUTICAL TABLETS:

As against the ancient and medieval times, today there are a number of reasons for coating the Pharmaceutical Tablets. Some of them can be listed as under:

# To arrest and hold the bitter taste of the tablet inside the sweet coat

# To arrest and hold the unpleasant odor of the tablet inside the sweet coat

# To protect the tablet Or pill from the damage that can be caused during manual handling

# To avoid damage to the surface of the tablet Or pill due to any unwanted substance such as water, oil Or any other chemicals

# To protect the tablet from light or specific kind of rays of lights

# To provide overall protection to the tablet Or pill

# To avoid early disintegration of the tablet Or pill (say in mouth or throat itself before reaching further).

# To make it easily differentiable and for brand building purpose

THEORY BEHIND THE PROCESS OF COATING THE PHARMACEUTICAL TABLETS:

While the purpose of the coating is to offer protection and to increase the time required for the disintegration of the Tablet Or Pill, it has always been true to make the coat as precise and thin as possible, so that neither it makes the tablet Or pill useless, Nor does it alter its medicinal properties Or cause any harm to the consumer.

Keeping this in mind, the pharmaceutical Or nutraceutical Or Herbal medicine manufacturers need to overcome the challenges as under:

# Coating layer has to be uniform across all the tablets Or pills

# Coating layer has to be uniform within the surface of a tablet Or pill

# Coating layer should be so precise that it should melt Or dissolve at the right place (example say in gastrointestinal track or stomach etc) and at the right time.

# Coating layer should be harmless and under no condition should the coating material change its properties Or form any sort of bonding with the tablet mass

# Coating layer also brings an aesthetic appearance to the tablet. If not coated properly, sometimes the color variation makes it look non pleasing.

The popular types of coatings include sugar coating, film coating, enteric coating, controlled release coating, other Or specialized coating such as electrostatic coating, dip coating, compressed coating etc.

Let's discuss the commonly used equipments for coating purposes as follows:

COATING PAN:

Coating Pan is the most simplest and most commonly used coating equipment in the industry. Coating Pans varies in sizes ranging from 12" diameter (lab model) to 72" diameter (commercial model).

WORKING PRINCIPLE:

The Tablets Or Pellets or other items (to be coated) are added to the coating pan which is kept rotating at a low rpm. The coating solution is sprayed on the rotating items with the help of the spraying system while the pan is under rotation. A constant flow of hot air is applied over the mass so as to dry the film of coat faster.

MAJRO COMPONENTS OF A COATING PAN:

1. Coating Pan Or Bowl: It is an ellipsoidal pan which is meant to rotate across an axis which is tilted (ie at an angle of 45 degrees with the horizontal and the vertical plane) with the help of an AC motor. The speed of rotation is kept very low, so that the coating is effective without any damage to the tablets Or pellets.

2. Hot Air Blower: An attached Hot Air Blowing device is provided which contains an external centrifugal air blower driven by a high rpm AC motor, an inline set of electrical air heaters, set of inline air filters, a connecting duct (SS316 Or SS304) etc. The utility is to blow the hot air over the coating surface for drying it faster.

3. Spraying System: The Spraying system consist of a small agitated solution tank, a peristatic pump (AC motor driven), telescopic stand, Spray Gun and pneumatic fittings. The utility of the system is to spray the coating solution inside the coating pan with a regulated and constant speed.

4. Mountings: The system is mounted on a SS304 Or MS + Epoxy Painted stand, with Motor and Gear Drive supported (for coating pan).

5. Dust Extractor and Exhaust Blower: The exhaust assembly including the Dust Collector, Blower, Cyclone separator etc are optional.

6. Operating Panel: Either a Flame Proof Or Non-Flame Proof operating Panel with motor on-off and speed regulator controls are provided. The system can be optionally consists of a PLC and HMI too.

(Pic Ref: www dot jicon dot com)

AUTO COATER:

Autocoater is a sophisticated and an automated version of a typical Coating Pan. As the name suggests, the manual steps involved in the operation of a Coating Pan are automated in this equipment.

FLUID BED COATER:

Unlike a Coating Pan Or an Auto- Coater, the Fluid Bed Coater works on the principle of Fluidization, where, the granules or pellets to be coater are fluidized in a FBP ie a Fluid Bed Processor. The coating solution is then sprayed into the FBP which forms a deposit on the external surface of each fluidized particle Or granule. The fluidization velocity and the spraying force is so maintained that we get the uniform coating on the granules and pallets.

Lets discuss a comparative Merits and Limitation of all these three equipments in the upcoming blog post.

Meanwhile, please feel free to contact incase of any queries, questions Or suggestions on this Or any other topic at shg.techo@gmail.com

TABLET COMPRESSION MACHINE BASICS

2022-04-23T23:40:00.000+05:30

INTRODUCTION TO A PHARMACEUTICAL TABLET :

Pharmaceutical Tablet is a kind of a 'solid unit dosage form' of a medicine containing an excipient (inactive substance which acts as a medium Or vehicle for the active substance), which may Or may not contain a diluent (a substance that can be used to dilute something).

Tablets are most commonly used form of medicines, which are meant to be administered orally. The reason behind tablet being so popular and being the top choice of the medical practitioners (doctors) lies in its physical characteristics. Tablets are compacted to a definite (and uniform) size and shape. Those are easy to handle without getting damaged, easy to pack Or store, requires limited space due to size and shape, can be easily and effectively combined with other forms of solid unit dosage (ex. filling a capsule with a tablet inside along with powder Or granules), has a low to moderate cost of manufacturing, can be coated with different colors Or quality enhancing solutions and can be embossed with branding etc.

Though Tablets are easy for human consumption (orally), few people (especially children) may find it difficult to do so. However, a large population of people across the globe find it easy to consume it orally, hence, tablet manufacturing is the most common part of the pharmaceutical formulations and manufacturing.

OVERALL PROCESS OF TABLET MANUFACTURING (API TO FORMULATION):

The overall process can be explained with the help of a Flowchart as under. Note, the process can have a many variations viz. a few additional steps like addition of a binder Or solution, drying, multi-milling Or co-milling and their repetitions etc to name a few.

HOW DO THEY MANUFACTURE A TABLET:

As discussed, tablets can be manufactured in a shape of a solid flat Or bioconvex dishes Or spherical granules. Tablets are manufactured mostly by compression and compacting technique taking into consideration the physical properties of the powder Or mixture (ex. size, shape, rigidity, elasticity to name a few).

The two types of Tablet Compression Machines are

(a) Single Station Tablet Press and

(b) Multi Station Tablet Press

While the Single Station Or Single Punch tableting machine is popular amongst the laboratory scale Or R&D laboratories, the Multi-Station Or Rotary Press is common for high output production rate operations.

(Pic Ref: www dot youtube dot com slash watch?v=g4rrGMJqEdk)

A Single Station Tablet Press (also known as Single Punch Tablet Press) makes use of only single punch station comprising of a pair of upper and lower punch and a die cavity. Whereas, Incase of a Multi Station Tablet Press (also known as Multi Punch Tablet Press), there are a number of stations viz. 8, 27, 37 and so on, where, each station has a pair of punches working on a die cavity.

MAJOR COMPONENTS OF A COMMERCIAL TABLET COMRPESSION MACHINE:

Let's understand the part names and their functions used in either Single Press Or Multi Press machine

Hopper: Feed Hopper is meant for charging the material viz. powder Or granules, which is fed either manually Or with some material transfer device.

Upper Punch, Lower Punch and Die Cavity: The tablet formation takes place due to the synchronized and coordinated actions of upper punch, lower punch and the die cavity. Both the upper and lower punches are vertical cylindrical machined metal parts with the central body known as Barrel, and other two ends are known as Head and Stem respectively. The Head also has a Neck which connects the Head with Barrel.

For the sake of understanding, if you compare it with a human body, the Barrel is your middle portion (chest and stomach), Head is the head which takes pressure from the compression roll, and Stem are like both the legs together, which acts on the slug for formation of a tablet.

The die cavity is a precisely machined cavity, where the stem of the upper and lower punch protrudes into with a force for shaping the slug into a tablet. The size (diameter and thickness), shape and the weight of a tablet totally depends on the die cavity.

Upper Punch has its stem pointing downwards (towards the die cavity), whereas, the lower punch has its stem pointing upwards (towards the die cavity).

The stem of the lower punch is longer than the stem of the upper punch. It is so because, the lower one also works towards the ejection of the tablet formed.

Cam Tracks: Cam Tracks plays a very important role in ensuring an accurate and precise movement of the upper and lower punches. The lower cam track is especially responsible for movement of lower punch during the filling stage, such that, the die cavity is properly filled Or overfilled (the excess mass further gets removed). Similarly ejection cams control the movement of the lower punches such that the tablets gets successfully ejected.

Pre Compressions and Main Compression Rollers: The compression rollers basically creates Or exerts the pressure on the punch heads, forcing them to move their stems towards the die cavity.

Pre compression rollers create lower pressure with an objective of removing entrapped air from the die cavity and prepare the slug for taking a new shape.

The main compression rollers builds a higher pressure thus ensuring the tablet formation takes place.

Take Off Blade and Discharge Chute: The take off blade guides the tablets towards the discharge chute, from where, the tablets get going to a collection pot Or bag.

TYPES OF TOOTING (D TYPE VS B TYPE) THAT DECIDES THE SIZE AND SHAPE OF A TABEL:

As discussed above, the punches and die cavity decides the size, shape and weight of the Tablet. The set of punches' and die together forms a Tooling.

Based on the sizes and shapes of tablets used for human consumption, there are two different types of tooling used viz. D Type and B Type of tooling.

(Pic Ref: www dot pharmapproach dot com)

The pic. above illustrates the difference between D type and B type tooling. The same can be summarized as under:

D Type (Max Tablet Size = 25/25mm): Punch Length = 133.6mm, Punch Diameter: 25.4mm, Die Diameter: 38.1mm, Height of the dies: 23.82mm,

B Type (Max Tablet Size = 16/19mm): Punch Length = 133.6mm, Punch Diameter: 19mm, Die Diameter: 30.15mm, Height of the dies: 22.22mm,

DB Type (Max Tablet Size = 19/19mm): Punch Length = 133.6mm, Punch Diameter: 25.4mm, Die Diameter: 30.15mm, Height of the dies: 23.22mm,

BB Type (Max Tablet Size = 13/24mm): Punch Length = 133.6mm, Punch Diameter: 19mm, Die Diameter: 24.0mm, Height of the dies: 22.22mm,

MATERIAL OF CONSTRUCTION AND SURFACE FINISH:

Tablet Compression Machines need to follow the GMP guidelines. Product Contact parts are made out of SS316 and the surface finish is usually matt finish. The Non Contact parts can be SS304 and surface finish could be matt finish.

GRANULATION AND RAPID MIXER GRANULATOR (RMG)

2022-04-09T01:31:00.003+05:30

WHAT IS GRANULATION:

Granulation is the process of forming granules (i.e. compacted group of particles) by application of forces of attraction amongst the particles within the mixture. These forces could be adhesive (bond formation between the molecules of dissimilar materials ex. water with solid), Or cohesive (bond formation between the molecules of the same Or similar materials ex. solid with solid), Or Vanderval's forces of attraction (i.e. the not-so-strong electrostatic forces between atoms or molecules). Important point to be noted here is that the process of Granulation should be verifiable, repeatable and should always give consistent results every time.

In this blogpost, we will discuss granulation in the Pharmaceutical Formulation point of view.

WHERE AND WHY IS GRANULATION REQUIRED:

Granulation ensures or aim at attaining uniformity of the material mixture. Many a times (especially true in case of pharma manufacturing) it is utmost important that each small group of particles should contain right proportion of all the components. In other words, each granule Or a group of compacted particles should be a representative (in terms of the uniform composition) of the overall mass.

ADVATNGATES OF GRANULATION:

Some of the important advantages of the Granulation Process are as follows:

# Granulation ensures uniform distribution of each component of the mass, thereby achieving proportionate composition of the granule. In simple language one can say that, each granule acts as a representative sample of the entire mass Or mixture.

# Granulation increases the flow ability (or flowability) of the feed material.

# Granulation binds the particles together, thus increasing the density and reducing the dusting during the operation.

# Granulation helps in producing the quality tablets which are helpful in achieving the desired effect after consumption by human.

GRANULATION PROCESS AND MECHANISM:

Usually, this can be achieved by either a Wet Granulation method Or a Dry Granulation method. Wet granulation involves addition of a liquid with Or without a binding agent. Whereas, incase of a Dry Granulation, the particles are subject to a high pressure, thus gets attached to each other forming a not-so-strong solid like structure.

Many theories on forces of attraction helping the granulation process has been published worldwide such as Formation of Solid and Liquid Bridges, Partial Melting and Re-crystallization, Mechanical Interlocking between the particles etc. To facilitate these processes (especially in case of a wet granulation), the concept of High Shear Granulation comes into picture.

INTRODUCTION TO RMG (RAPID MIXER GRANULATOR):

As the name suggests, an RMG facilitates formation of granules from the powder mass by mixing the powder particles, wetting the powder particles with the help of the granulating liquid or binder, attaining spheronization, making the granules denser and hence stronger etc.

The powder particles are forced to undergo a pattern of mechanical actions such as rising, tumbling and whirling. Due to the repetition of these actions and in the presence of the liquid or a binder, the particles develop the bonding for each other, thus, forming the grain like shape.

(Pic Ref: www dot jicon dot com)

MAJOR COMPONENTS OF AN RMG (RAPID MIXER GRANULATOR):

1. Mixing Bowl: This is a vertical cylindrical vessel with slightly conical top with a flat bottom with an agitator shaft protruding inside the bowl. The L/D ratio of this stirred tank vessel is much lesser than one, as D is much larger than L. This is because the powder Or mass to be mixed needs sufficient area for rising, tumbling and whirling while rotating around the vertical axis.

The Top Lid Or Cover is usually hinged to the bowl. However, it can also be of hydraulically liftable type. A good quality high density sealing gasket is used to seal the top lid flange with the bowl flange tightly. Sometimes, an open Or a gritted nozzle is provided on the top nozzle for easy charging of raw material Or binder solution etc.

In tank WIP (wash in place) nozzle can be provided optionally.

2. Impeller Assembly: The agitator is always a bottom entry one (meaning the motor driven shaft protrudes the bottom of the vessel inside) with the blades rotating parallel to the flat bottom. The blades are specially designed and angled such that they slightly lift the mass and allow it to jump across the blade. At the same time they keep pushing the solid mass bed. This constantly keeps the mass in action and undergo rising-falling-tumbling. Due to the rotational motion, slowly the particles that coalesce start gaining spherical shape.

A good quality bearings and sealing mechanism is used to avoid any kind of powder leakage from the entry point of the agitator.

The Rotational Speed (RPM) of the agitator can be controlled with variable frequency drive.

The blades assembly can be dismantled for cleaning Or maintenance purpose.

3. Chopper Blades: A high speed lump breaker Or chopper assembly is provided in the laterla direction inside the bowl. The shaft of the lump breaker protrudes the cylindrical wall of the bowl inside the vessel and has knifes places on the shaft specially designed to break the bigger lumps formed due to addition of liquid or binding agent in the rotating mass.

Again a good quality sealing mechanism is used to avoid powder leakage from the entry point of the lump breaker.

4. Pneumatically operated granule mass discharge system: Just like the chopper assembly, another nozzle (slightly bigger in size) is provided on the lateral side (i.e. on cylindrical wall of the vessel) closer to the bottom. This nozzle has a plunger type valve, which is pneumatically operated. When the granulation is on, this valve is flushed to the curvature of the opening of the bowl. However, at the time of discharging the material, the plunger moves axially making way for the granules to enter the nozzle and get removed from the Y type branching.

Many a times the Y type branch has a chute attached to take the granules to a vibrosifter or a conical mill.

5. Operating Platform and Ladder: The motor and gear assemblies are concealed under the operating platform which is at a height. Hence, a connected ladder with railing us provided for ease of material loading and supervision of the operation.

6. Operating Panel: In pharmaceutical formulations, many a times the granulation equipments are PLC -HMI controlled. However, the usual push button type relay based operating paenl are not uncommon too.

POINTS TO BE TAKEN INTO CONSIDERATION WHILE PLANNING AN RMG (RAPID MIXER GRANULATOR):

Some of the important points which are strongly related to RMG and require attention while planning for an RMG are as follows:

1. Capacity and Space Planning: RMG capacity should be planned based on the two most important parameters viz. (a) bottlenecking capacity of the entire granulation line (b) space availability.

Mostly RMG requires a very large area (due to operating platform and ladder). Also, many related operations are preferred to be carried out in the same area where RMG is placed such as Sifting, Milling (Co-Milling or Multimilling), Drying etc. Also, the Mass Mixer and Paste Kettle used prior to granulation too are placed in the same room at times.

Looking at all these, the space can become a bottleneck and hence the capacity Or batch planning may get affected.

2. Anciliary Equipments Planning: As discussed above, the capacities of the related ancillary equipments such as Paste Kettle, Blender, Dryer, Mass Mixer and other granulation line equipments Or mass transfer equipments such as Lifter- Loader etc must be planned carefully.

3. MOC and Surface finish: Depending on whether its a GMP or a Non-GMP operation, the material selection (MOC) is done. Unusually the surfaces are extremely smooth and the finish is of a high RA value, so as to avoid any opportunity of corrosion.

4. Ergonomic design: Every aspect of the design including the ladder, the railing, the top lid, material charging nozzle, the platform height, the discharge mechanism, the operating panel etc should be ergonomically designed. This is extremely important not only in operators' safety point of view, but also important in increasing their efficiency and raising the overall quality and output.

Please feel free to contact incase of any queries, questions Or suggestions on this Or any other topic at shg.techo@gmail.com

PART 1 OF 2: MOC (MATERIAL OF CONSTRUCTION) FOR GMP AND NON GMP PROCESS EQUIPMENTS

2022-03-30T02:46:00.007+05:30

INTRODUCTION TO MATRIAL SELECTION AS PER GMP GUIDELINES:

Unit Operations in manufacturing industries such as Pharmaceutical, Foods, Cosmetics and in some cases Chemicals many a times deal with corrosive environment. The ingredients and the parameters in used may lead to serious corrosion leading to erosion of the process equipments, followed by contamination and cultivation of impurities in the end product. Therefore, selection of the Material of Construction of the machines or equipments become the most important paramter.

As a Process Design Engineer, the ideal reasoning behind making appropriate selection of MOC should be in accordance with the following premises:

# Does the Unit Operation Or Process demand Or needs to follow a statutory mandate Or Standard, such that it has to be a corrosion-proof operation?

# Even if it doesn't, are there any chances of corrosion taking place during the reaction or during the course of the operation?

# Does the operation under consideration involves elevated temperatures/pressures Or use of salts or acids Or use of Halides Or other corrosion provoking materials?

# Does it involve too complex a process Or involves highly expensive Or sensitive products?

# How can the MOC selection increase the longevity of the equipments and hence help build on ROI and Profit?

UNDERSTANDING THE GUIDELINES AND LIMITING PRICIPLES USED IN SELECTION OF MATERIAL (METALS) FOR FABRICATION:

GMP (Good Manufacturing Practice) and cGMP (Current Good Manufacturing Practice): These are the regulations which are mandated by the FDA i.e. Food and Drugs Administration.

Usually, the FDA controls and regulate the quality parameters applicable in industries like Food manufacturing, Medicines manufacturing etc. GMP guidelines have been especially formulated as a preventive and corrective measure on the possible grave quality issues, hence are mandatory and statutory in most of the cases.

GMP and cGMP guidelines (especially applicable for the process equipments) revolve around the premise of protecting the equipment from any kind of corrosion, thus, preventing the product from contamination. Some examples includes the High Quality Surface Finish of an equipment, smooth and buffed, crevice free surface, absence of any sharp corner Or edge etc.

CORROSION, TYPES AND REMEDIES: Corrosion is a phenomenon by which the material (especially metals) deteriorates Or gets eroded Or degraded in terms of its mass, shape, size and volume under the influence of the surrounding parameters. These changes takes place at a molecular level, wherein electrons flow from one part of the metal to another part. The part from where the flow of electrons starts gets eroded.

(Pic Ref: www dot sciencedirect dot com slash topics slash materials-science slash crevice-corrosion)

IMPORTANT METALS USED IN PHARMACEUTICAL, FOOD, COSMETICS AND CHEMICAL MANUFACTURING PROCESS:

Selection of the material of construction for the process equipments becomes easy upon understanding the concepts like Corrosion, GMP, Non- GMP etc.

GMP guidelines asks for Corrosion-Resistant material to be used for construction of the process equipments. Hence, Stainless Steel and some other alloy steels mostly becomes the natural choice for the construction of the Equipments used for Pharmaceutical, Nutraceutical, Herbal and Food production.

Inorder to discuss about the Alloy Steel and other types of Austenitic Stainless Steel (i.e. specially heat treated alloy steel containing Chromium and Nickel), lets first understand the properties and importance or the components of the most common Alloy Steels.

Chromium (Cr): Imparts the lustrous finish to the alloy. Improves corrosion resistance properties. Most importantly, allows the alloy to withstand a very high temperature.

Nickel (Ni): Imparts Hardness, Ductility and Formability to the alloy steel.

Carbon (C): Imparts Hardness and Strength to the alloy steel. However, lower is the Carbon content, higher is the corrosion resistance.

Molibdenum (Mb): Improves metal surface properties such that the pitting and surface unevenness is minimized.

Titanium (Ti): Imparts Hardness, Ductility and Formability to the alloy steel.

Manganese (Mn): Imparts Strength, Toughness and Hardenability of the alloy steel.

Let's see some of the common types of Alloy Steels used as per GMP and GMP guidelines.

SS316 (ASTM A240/ ASME SA 240 Grade 316 Stainless Steel Sheet):

(Cr - 16 to 18%, Ni - 10 to 14%, Mo - 2 to 3%, C - 0.08%, Mn - 2%)

SS316L (ASTM A240/ ASME SA 240 Grade 316 Stainless Steel Sheet):

(Cr - 16 to 18%, Ni - 10 to 14%, Mo - 2 to 3%, C - 0.03%, Mn - 2%)

SS304 (ASTM A240/ ASME SA 240 Grade 304 Stainless Steel Sheet):

(Cr - 18 to 20%, Ni - 8 to 10.5%, Mo - Not Applicable, C - 0.08%, Mn - 2%)

SS304L (ASTM A240/ ASME SA 240 Grade 316 Stainless Steel Sheet):

(Cr - 18 to 20%, Ni - 8 to 12%, Mo - Not Applicable, C - 0.03%, Mn - 2%)

SS321 (ASTM A240/ ASME SA 240 Grade 321 Stainless Steel Sheet):

(Cr - 17 to 19%, Ni - 9 to 12%, Mo - Not Applicable, C - 0.08%, Mn - 2%)

Hastelloy C22 (UNS N06022, Alloy C22):

(Cr - 20 to 22.5%, Ni - 50 to 55%, Mo - 12.5 to 14.5%, C - 0.01%, Mn - 0.5%, CO - 2.5%, Fe - 2 to 6%, P - 0.02%, Si - 0.08%, S - 0.02%, W - 2.5 to 3.5%, V - 0.35%)

Hastelloy C276 (UNS N10276, Alloy C276, Inconel 276):

(Cr - 14.5 to 16.5%, Ni - 50 to 55%, Mo - 15 to 17%, C - 0.01%, Mn - 1%, CO - 2.5%, Fe - 4 to 7%, P - 0.04%, Si - 0.08%, S - 0.03%, W - 3 to 4.5%, V - 0.35%)

Please watch out for the next part of this blogpost emphasizing more on Types of Corrosion and Live Examples of failures of Pharma Equipments!

PART 2 OF 3: MICRONIZER OR AJM (AIR JET MILL) OR A FLUID ENERGY MILL:

2022-03-20T03:32:00.006+05:30

LOGICAL AND PRACTICAL ASPECTS OF MICRONIZATION:

Having discussed about Micronizer Or Air Jet Mill Or Fluid Energy Mill, as well as its working (in Part 1 of 3), it is now the time to discuss the practical aspects of the milling operation with the logical explanations.

(Pic Ref: www dot promasengineers dot com)

MATERIAL FEEDING:

As discussed earlier, a vertical cylindrical vessel with usually a hemispherical bottom is used for charging the feed material. The horizontal agitator keeps the material shuffling and the horizontal screw at the bottom pushes it towards the ventury based feeding line. Important aspects to be taken note of are as under:

# Feed Size Desired: Less than 1000 Microns (Or 1 mm). It is so because Micronizer is meant for milling already fine particles to super fine level.

# RPM of the Agitator and Screw: Usually the RPM is never more than 100 and not lesser than 5 to 6. Higher the RPM, faster is the pushing of the material into the Milling Chamber.

# Volumetric Vs Gravimetric Feeding: Micronizers usually use Volumetric feeding only, where the RPM of the Screw decides the material to be pushed Or feeded to the milling chamber. On the other hand, a gravimetric feeder means a mechanism that always keeps an eye on the pre-set value of the weight of the material and the weight variation drives the flow of the feed. For the purpose of Micronizer, feeding of known quantity (in terms of weight) is actually necessary. However, looking at the complexities of the operation, most of the organizations prefer the auger driven feeding i.e. the Volumetric Feeding.

MICRONIZATION:

As discussed in the previous post, the micronization here necessarily is achieved by particle to particle collision under the influence of the turbulence created by high pressure fluid (usually air) jet entering the milling chamber. Important aspects to be taken note of are as under:

# Primary Pressure: Also known as the Feeding Pressure. The Primary Pressure Or P1 is usually never more than 8 to 10 bar, and, can be as less as 1 to 2 bar. Lower P1 leads to slowing of the overall output i.e. the milled powder collected at the receiver.

# Secondary Pressure: Also known as the Milling Pressure. The Secondary Pressure Or P2 is usually never more than 10 to 12 bar, and, can be as less as 1 to 2 bar. Lower P2 leads to fine milling. It is because when we lower the P2, the powder particles inside the chamber gets more residence time, resulting into finer milling.

# Vacuum Balancing Line and Ventury: As discussed earlier, the feeding line has a ventury line attached at the bottom at an angle (as shown in the fig below). The primary pressure P1 pushes the air through the ventury inside the chamber. Due to sudden expansion of the air in the nozzle (after ventury opening), a good amount of negative pressure is created, which is responsible for pulling the material down inside the milling chamber.

Sometimes the negative pressure created is so high that it can choke the feeding line by the powder particles and imbalance the pressure inside the chamber resulting into back pressure (i.e. powder can be gushed out of any opening into open atmosphere). To avoid this, a bypass line is provided near the feeding nozzle, and the other end of this line is either kept open to atmosphere with a filter cloth covering it, Or is attached to the Hood of the Filter Bags Or Finger Bags.

(Pic Ref: www dot sturtevantinc dot com)

SEPARATION OF THE MILLED PARTICLES FROM AIR:

As discussed in the previous post, the fine particles travel through a central pipe emerging from the center of the milling chamber to the Cyclone Separator and a series of Filters Or Finger Bags. Important aspects to be taken note of are as under:

# Sudden Pressure Drop due to a Volumetric Expansion: While inside the milling chamber, the air and material particles are subject to a very high pressure (say in the range of 8 to 12 bar). However, post milling the high pressure air stream along with low density (milled) powder particles enters to expansion chamber Or filter bag hood, which is more than 20 times bigger in volume (as compared to the milling chamber volume). Hence the pressure drops to nearly atmospheric or lesser than one bar.

# Cyclonic Action coupled with Coarse and Fine Filtration: The air stream with sudden expansion looses its pressure, however, due to the already attained high momentum can escape the cyclonic action. To avoid this, a series of finger bags Or filter bags (usually 5 to 10 micron size and made up of Polypropylene or Satin material) are used to arrest the powder inside and allow the air to escape through. Note - calculating the required surface area of filtration is a crucial part here.

The powder particles carried by low pressure and low velocity air are then allowed to settle down under the cyclonic action in the receiver collected at the bottom of the cyclone separator.

# Further Filtration of the escaping Air: There is a possibility of powder particles reaching a Nano Or super fine size range. In such cases, the preliminary finger bag filters may not be able to arrest the powder particles completely. This can lead to both loss of material, as well as the contamination Or Air pollution.

To avoid this, a series of external filters are attached in the exhaust air stream viz. Fine Filter (say close to 3 micron aperture) and a HEPA filter (0.3 micron aperture). Incase of a HEPA filter, a differential pressure guage Or transmitter might be required, which will indicate if the filter is choked Or not (so that it can be replaced).

# Quantity, Quality and Pressure of the Air Requirement for the System: As discussed earlier, the milling media in Fluid Energy Mill or Micronizer is mostly Dry Air only.

It needs to be Dry and Oil free, as, otherwise it will help create agglomeration of the powder particles instead of fine milling.

In general a 12" Or 350mm diameter Milling Chamber needs almost 220 CFM (cubic feet per min) worth Air Flow Rate in the main header. Incase the flow rate is lower, the milling will not be consistent.

There is a possibility of powder particles reaching a Nano Or super fine size range. In such cases, the preliminary finger bag filters may not be able to arrest the powder particles completely. This can lead to both loss of material, as well as the contamination Or Air pollution.

Note: Please do not forget to read through Part 1 and Part 3 of this series, as it is the continuation of the discussion.

PART 3 OF 3: MICRONIZER OR AJM (AIR JET MILL) OR A FLUID ENERGY MILL:

2022-03-20T03:27:00.003+05:30

INTRODUCTION TO PARTICLE CHARACTERIZATION AND SIZE DISTRIBUTION ANALYSIS (PSD):

In order to understand the theory and methods of effective Micronization, one must understand about Particles and the Particle Size Distribution in detail.

A particle is a discrete sub portion of a substance. Although, the materials which are made up of particles include powders, granules, suspensions, emulsions, slurries, aerosols and sprays, we are limiting our discussion to powders and granules only.

It is extremely important to study and carry out routine analysis of the product Particle Characterization, as it helps yield superior control over the product properties, thereby leading to superior quality production. The properties of particles undertaken for studies often includes Particle Size, Particle Shape, Surface Properties, other Mechanical Properties and Microscopic properties. Depending on the material Or product under study, the parameters Or combination of the parameters may vary. However, the most common parameters chosen for analysis are Particle Size and Shape.

(Pic ref: This is the actual report of PSD analysis after Jet-Milling of Guanidine Nitrate done for one of my Clients. Guanidine Nitrate is from Nitroglycerin family, hence carries Explosive characteristics).

When it comes to defining the size of a particle, one cannot always imagine any particle to be a prefect sphere, hence, ideally a 3D or a Three Dimensional approach is always better or recommended. Infact, many a times a particle size is determined with the concept of Equivalent Spheres, where, the particle size (say for example the diameter) is defined by the diameter of an equivalent sphere, which posses the same properties (as that of particle under study) like mass Or volume etc. The different measurement techniques require different equivalent sphere models, hence, may yield different Or non uniform results.

(Pic ref: www dot malvernpanalytical dot com)

PARTICLE SIZE DISTRIBUTION OR PSD:

Since, it is not possible for each particle of a sample to posses the same dimensions (also known as Mono Dispersion), PSD will mean the Statistical Distribution of particles of different sizes. As a common practice, the Particle Size Distribution is represented as a Frequency Distribution Curve Or a Cumulative Distribution Curve.

(Pic ref: www dot malvernpanalytical dot com)

The 'Mean' here can be of three types viz.

1. Number Length Mean Or Arithmatic Mean (Important with respect to the total number of particles)

2. Surface Area Mean Or Sauter Mean Diameter (Important with respect to the total surface area)

3. Volume Moment Mean Or De Brouckere Mean Diamater (Important with respect to the size of those particles which constitute the bulk of the sample volume).

As you may be aware from the basic studies of statistics that Median is the middle most number when all the sizes are arranged in an ascending order. Similarly, a Mode is the size of the highest frequency.

WHAT IS MEANT BY 'PARTICLE CHARACTERIZATION TECHNIQUES':

This concept becomes important once we have the sample in hand to be analyzed for PSD. There are a many such characterization techniques available, and one can choose the most suitable based on questions like important properties of the particles, size range, Wet Dispersion Or Dry dispersion of the sample and budget available etc.

Based on all these parameters, the most common Techniques used are as under:

1. Laser Diffraction (uses Mie theory of light scattering and assumes Volume Equivalent Sphere model): Measurement of PSD by measuring the angular variations in the intensity of the light scattered as the laser beam passes through a dispersed sample.

2. Dynamic Light Scattering (also known as Photon Correlation Spectroscopy Or Quasi Elastic Light Scattering): Powder Particles in fluid suspension undergo Brownian motion due to the thermally induced collisions between suspended particles and solvent particles. When illuminated with laser, the intensity of the scattered light fluctuates at a rate which is dependent on the size of the particle.

3. Automated Imaging: This technique is useful for particles of size ranging for One Micron to Several Millimeters. The analysis of the individual particle images captured from dispersed samples yields particle size, shape and other physical properties.

4. Electrophoretic Light Scattering (ELS): Here the Electrophoretic Mobility of particles in dispersion is measured. Electrophoretic mobility means the velocity of mobility of the charged particles when the dispersion is introduced to a cathod and an anode.

SAMPLE DISPERSION:

As discussed above, a Particle Characterization Technique requires a Dispersion, whereby, the particles are spatially separated. The two most common types are dispersions include a Wet Dispersion and a Dry Dispersion.

Incase of a Wet Dispersion, a liquid is used for creating a suspension of the powder particles in the liquid by lowering the surface energy of the particles and thus reducing the forces of attraction between particles.

Incase of a Dry Dispersion, a stream of Flowing Gas Or Dry Clean Air makes the particles suspended by various mechanisms viz. Particle to Particle Collision, Particle to Wall Collision and Velocity Gradient caused by shear stress etc. Dry Dispersion is not recommended for particles of size less than One Micron. This is because there may be very high forces of attraction between the fine particles.

SUMMARY AND THE APPLICATION OF THE DISCUSSION FOR MICRONIZATION:

The PSD analysis and Particle Characterization Principles and Techniques must be known to the Process and Quality department, as without which they cannot deduce the Extent of Micronization including the Feed Micron Size, Final Micron Size, behavior of the parties under the influence of the turbulence and other design parameters.

Note: Please do not forget to read through Part 1 and Part 2 of this series, as it is the continuation of the discussion.

PART 1 OF 3: MICRONIZER OR AJM (AIR JET MILL) OR A FLUID ENERGY MILL:

2022-03-16T02:05:00.016+05:30

INTRODUCTION TO AN AIR JET MILL OR A FLUID JET MILL OR A MICRONIZER:

Many a times a chemical reaction Or a unit operation may yield better results when it involves fine particles over coarse ones. This is because particles as fine as Micro Or Nano offers more surface area for reaction, better absorption ability, uniformity, as well as, better solubility and mixing properties in various fluids.

To reduce the particle size of powder Or solid material, the most commonly used operations include Milling, Grinding and Micronizing.

Mechanical size reduction operations such as Milling and Grinding generates heat (due to the direct impact Or collision with the powder) and are not suitable for the heat sensitive materials. However, the Air Jet Mill Or the Micronizer uses fluid energy (mostly Air) to generate turbulence inside the milling chamber carrying the powder particles, leading to size reduction, as low as a Nanometer.

(Pic Ref: www dot sturtevantinc dot com)

(Pic Ref: www dot promasengineers dot com)

PRINCIPLE OF WORKING OF FLUID JET MILL OR AIR JET MILL OR MICRONIZER:

Fluid (Air) Jet Mill Or Micronizer works on the principle of 'particle to particle collision' taking place under the influence of induced fluid Or air turbulence. A high pressure fluid (mostly Air) is introduced tangentially inside a closed metal basket called Milling Chamber. A feeding nozzle connecting the feeder chamber, milling chamber and ventury nozzle at an angle, under the influence of another stream of fluid (air) pressure pushes the feed material inside the milling chamber. Under the high pressurized air flow inside a closed space, the particles are forced to colloid with each other and on the walls of the milling chamber, thus, reducing in size. The centrifugal and centripetal forces acting on each particle travelling in a rotational motion pushes the large size particle to stay closer to the inner calls of the chamber and the lighter or smaller particles to gather at the center of the milling chamber. The exhaust pipe at the center carries the stream of ligher particles to the cyclone separator Or series of cylone separators, which also contains a series of bag filters for arresting the fine powder particles and letting off the low pressure air.

(Pic Ref: www dot sturtevantinc dot com)

INDUSTRIAL APPLICATIONS:

Almost all manufacturing industries, where size reduction to micrometer Or nanometer is required, makes use of Fluid Energy Mill Or Air Jet Mill Or Micronizer. Few examples are Pharmaceutical Industries, Nutraceuticals, Herbal and Ayurvedic, Cosmetics, Food, Agro-chemicals and Chemicals, Explosives manufacturing, Metal Powders manufacturing, Polyomer industry etc.

MAJOR COMPONENTS OF THE FLUID ENERGY MILL OR AN AIR JET MILL:

1. Feeding Chamber: Material feeding can be either by a Vibratory Feeder Or by a Screw Feeder (Augar). Vibratory feeder is used for the products which are very light and may not get an appropriate push with the screw. The Screw Feeder is more prominently used in the industry.

Usually, a feeding chamber is a vertical cylindrical vessel with an open top lid for material charging and with a horizontal agitator (motorized externally) for material shuffling (which avoids ratholing). At the end of the feeder, usually a horizontal screw Or augar is fitted which is mostly powered by the same motor and gearbox which powers the agitator.

The agitator shuffles the powder mass to push it down on to the screw, whereas, the screw pushes the powder mass towards the exit ie. the ventury feeder nozzle.

2. Milling Chamber: Milling chamber is a closed basket made up of metal plates consisting of a Top Plate, Bottom Plate and the Circular Ring. Both the Top and Bottom plates are precisely machined so as to fit on the top and bottom of the Circular Ring. The assembly is closed by the use of eye bolts Or clamps such that it can easily withstand a high fluid pressure of 10 to 12 bar. The Top Plate contains a Feeder Nozzle with Ventury Tube and the Central Exhaust Pipe.

Milling Chamber can be either a Single Jet Or a Multi Jet one. The number of holes of the circular ring which allows the stream of high pressure fluid (air) enter inside the chamber tangentially decides if a milling chamber is called a Single Jet Or a Multijet milling chamber.

3. Ventury Nozzle and the Feeding Line: The Top Plate contains a feeding nozzle, which protrudes inside the top plate at an angle with the top flat surface of the plate. This nozzle has a ventury tube inline (fixed between the outlet of the screw feeder and the entry point of the milling chamber).

4. Primary Air Pressure: This is the fluid pressure Or air pressure provided to the feeding line and the objective of which is to push the feed material down inside the milling chamber. The high pressure air stream (in other words, the Primary Air) when passed through the nozzle with ventury undergoes sudden expansion due to ventury effect, This creates a small vacuum good enough to pull the powder material from the feeder line into the milling chamber.

5. Secondary Air Pressure: The fluid Or air pressure required to the create turbulence inside the milling chamber is also known as Secondary Air Pressure. This pressure along with the flow rate of the fluid media (Air in today's discussion) decides the output micron size, as well as, yield Or output in measurable quantity viz kilograms.

6. Central Exhaust Pipe: This is the pipe that connects the center of the Milling Chamber and the Cyclone Separator or Dust Collector. The powder particles when broken into smaller particles inside the milling chamber due to particle to particle collisions, get pushed towards the center due to density difference and eventually enters the central pipe which is directly connected to the cyclone separator.

7. Cyclone Separator And the Filter Bag Housing: This vertical chamber is divided into two parts viz. Filter Bag Housing and Cyclone Separator. The filter bag housing is nothing but the vertical cylindrical topmost cylinder which has a set of PP (polypropylene) filter bags fixed inside of approx. 5 to 10 micron size. The bottom conical part which acts as a cyclone separator is connected to the filter housing cylinder at its bottom. The butterfly valve is provided at the bottom of the conical cylinder to facilitate the discharge of the the fine powder into the receiver tank.

8. Powder Collection Vessel Or Receiver along with the Mechanical Lifting Trolley: A vertical cylindrical powder collection vessel Or receiver is attached to the bottom of the cyclone separator. The flange of the butterfly valve and the neck flange of the receiver must match each other so that both can be sandwiched in a common triclover clamp Or a Quick release coupling Or Eye Bolts. The neck to body part of this receiver is slanted. This is because even if the diameter of the cylindrical part of the receiver is large, the top neck flange can be of much smaller Or standard size viz 8 inch Or 10 inch or 12 Inch etc and hence can easily connect. The role of the mechanical trolley is to unload the receiver back on the trolley Or lift the receiver to a height such that the receiver flange and butterfly valve flange can match each other.

9. External Filtration Assembly Or Air Handling Unit: The exhaust air passing though the primary filter Or bag filters sometimes needs additional set of filtration. This optional feature can provide a set of three different filters fixed inside the housing filtration viz. Primary Filter (usually 5 or 10 micron), Secondary Or Fine Filter (usually 3 micron) and HEPA filter (0.3 micron)

10. Rupture Disc (Optional): In order to mitigate the possibility of any kind of an explosion, a rupture disc is provided on the cylindrical hood carrying the finger bags.

11. Air Manifold for branching the Incoming Air Flow: Air Jet Mill Or Micronizer essentially need an incoming Air Flow to be split into two halves viz. Primary Or Feeding Pressure and Secondary Or Grinding Pressure. This manifold separates the incoming Air Flow into the Primary and Secondary line with the help of the throttling valves and provision in the operating panel.

HOW TO ACHIEVE DESIRED PARTICLE SIZE IN MICRON

Please follow my next blog focusing on Desired Particle Size, Feed Pressure, Grinding Pressure and Air Flow Rate

MATERIAL OF CONSTRUCTION:

For pharmaceutical Or food applications (where GMP validation is applicable) the Contact Parts are of SS316 Or Higher Grade, whereas, the Non Contact Parts are of SS304.

Incase of Highly Abrasive Materials, the Milling Chamber is usually made up of Hardened Steel Or Alloy Steel i.e Lined with Silicon Carbide.

Incase of Non-GMP applications, both the contact and non contact parts can be SS304 Or MS based on the process requirement.

SURFACE FINISH:

In case of GMP setup, Product Contact surface is usually required to be of minimum 240 grit Mirror Finish and Non Contact surface is 180 grit matt finish.

SCOPE OF AUTOMATION IN MILLING OPERATIONS:

There are a few OEMS and Integrators who claims to have achieved an Automation in Air Jet Milling Or Micronization operation such that the inline sampler and tester randomly picks a scoop of powder from the output material and instantly determines its average micron size based on the pre-filled parameters. Based on the outcome of the computer based analysis, instantly the powder is either sent for further packaging (if passes through) Or sent back as a reflux to the feeding chamber (if it doesnt pass through). This kind of automation is extremely complex, as, the parameters to be chosen that can help us to infer that a particular set of particles can be of a particular micron size are different for different users. Also, there isn't much clarity if a set of parameters that can deicide the particle size by the help of a software can be applied and give effective results for all types of material. Therefore, this kind of an automation will always be a complex one and may not be accurate always.

However, many OEMS and manufacturing companies are able to successfully automate the Feeder Line and Output Line. Which means, the feed to the Feeder of Micronizer can be automated with the hep of a Screw feeder or a Vacuumized Powder Transfer. Same can be applied to the output material. We will talk in details about it in my upcoming blog on Material Handling Systems.

Note: Please do not forget to read through Part 2 and Part 3 of this series, as it is the continuation of the discussion.

COMPARATIVE STUDY BETWEEN OCTAGONAL BLENDER AND DOUBLE CONE BLENDER

2022-03-06T14:38:00.000+05:30

INTRODUCTION TO AN OCTAGONAL BLENDER and A DOUBLE CONE BLENDER:

As we discussed in the previous post on V-Blender, both 'Octagonal Blender', as well as, 'Double Cone Blender' are dry powder blenders i.e. solid-solid blender popularly used in Pharmaceutical, Food, Cosmetics and Chemicals industries. In both of these, a fabricated metal container (which carries the powder mixture) rotates across an imaginary horizontal axis i.e. a motorized horizontal shaft, so that the powder particles undergoes constant shuffling due to tumbling and shearing action, resulting into a thorough mixed mass. The bowls of Octagonal Blender and a Double Cone Blender are supported from both the sides with an A shaped metal support structure (just like a swing in a garden) and are rotated with the help of an AC motor and a gearbox.

WHERE AND WHY IS IT USED:

Both the Octagonal and Double Cone Blenders are popularly used in Pharmaceutical, Nutraceutical Manufacturing, Food Processing, Chemical and Cosmetics industries for carrying our operations like Blending, Mixing, Lubricating etc.

(Ref: Pics taken from Jicon Technologies Pvt Ltd, Mumbai India, website is www dot jicon dot com).

COMPARATIVE ANALYSISS BETWEEN 'OCTAGONAL BLENDER' AND 'DOUBLE CONE BLENDER':

1. Size, Shape and Geometry: Octagonal Blender, as the name suggests, consists of an Octagonal Shaped Closed Container. The side cross-sectional view of the Octagonal Blender can show a clear Octagon. Whereas, the Double Cone Blender, as the name suggests, consists of a bowl which has the top and bottom ends made-up of a metal cone, and a central portion is made-up of a low height vertical cylindrical drum. Please refer to the pictures attached above for more details.

2. Material Loading/ Charging and Unloading/ Discharging: Octagonal Blender has a material charging opening (also known as Manhole) which is usually is rectangular opening (located on the top of the blender when it is in a stationary position). The discharge Or unloading is usually done through a bottom circular nozzle which is closed by a butterfly valve usually.

Double Cone Blender too has two openings viz. Top Charging Circular Nozzle Or Manhole and a Bottom Discharge Nozzle sealed with a butterfly valve.

In both of these cases, the manholes are big enough. Octagonal has a rectangular and very big manhole with a removable metal lid, which is fixed to the blender body with the help of a set of Eye Bolts by placing a food grade silicon gasket at the interface. Whereas, incase of the Double Cone, the manhole is Circular with a neck flange and a Hinged Lid Or Cover that is fastened to the neck flange with the help of a set of Eye Bolts by placing a food grade silicon gasket at the interface.

Powder Or any other material loading and unloading Need Not Be Done manually always. There are methods like Vacuum Charging of the material Or Bin Loading etc. Incase of a vacuum charging method, the blender body is vacuumized by applying vacuum externally, and a closed chute is placed in the feed container, which allows the powder to be sucked inside the blender and gets arrested there.

Whereas, incase of a bin blender, a bin full of feed material is attached to the bottom butterfly valve of the blender. The powder falls inside the blender when the blender body is rotated upside down, and the butterfly valve is closed so that powder doesn't slide back in the bin upon bringing in to the original position. Please wait for my next blogpost on Charging and Discharging Methods in the Blender.

3. Blending Mechanism: Both the blenders follows a similar mechanism, i.e. rotation of the Blender Body around a horizontal axis, such that the powder mixture inside keeps shuffling continuously inside. However, the basic difference between the two can be explained with the help of their respective shape, size and geometry.

Incase of an Octagon, the powder particles mostly follows a shearing pattern. Which means, in low rpm rotation, the top most layer of the powder slides down (overcoming the angle of repose) and takes the bottom most position on the surface of the blender. The next eligible layer thus takes the upper position on the recently formed bottom layer. This way the entire powder bed keeps shuffling from top to the bottom. Also, the shallow cone formed at the bottom of the blender forces the powder particles to form cross currents and get thoroughly mixed.

Incase of the Double Cone, the powder particles undergoes simultaneous tumbling and shearing action. Since, both the apexes of the blender i.e. Manhole and Bottom Valve are of much smaller diameter than the central cylindrical diameter, the conical angle formed are steep. This allows the powder mass to contract in volume while the blender is in vertical position (i.e. either the manhole Or bottom valve is up), and expand in volume which the blender is in horizontal position. This way a thorough mixing takes place due to the continuous rotation of the blender body at a low rpm.

4. Space needed, Ease of Operation and Maintanance: Octagonal blenders due to its horizontal volume requires larger space and room. However, cleaning is much easies, as manhole is big enough for a person to enter inside for cleaning Or routine maintenance if any.

Double Cone Blender though can fit in a relatively smaller room, however, need a big headroom. In other words, larger the capacity of the Double Cone Blender, more is the height required for the blender to rotate. Also, cleaning and routine maintenance is slightly difficult (when compared with Octagonal blender), as the shape is complex for a person to enter inside through a manhole.

MAJOR COMPONENTS OF THE BOTH THE BLENDERS IN COMPARATIVE STYLE:

1. Main Bowl Or Container Or Shell with closing lids on manhole and a bottom valve: As discussed above, the Octagonal Blender is essentially a horizontal but octagonally shaped long box (Octagonal shape can be viewed in a cross-sectional or a side view). Whereas, the Double Cone Blender is a box made up of two cones joined to a low height hollow cylinder at the center (lookwise somewhat similar to the RCVD Or Rotocon Vacuum dryer).

2. Drive Assembly: Just like a V Blender, an AC motor along with a suitable Gearbox (mostly hollow shaft) is used for achieving a low RPM with a VFD (Variable Frequency Drive).

Caution: Spur-Pinion gear arrangement is economic and effective, as, blender when stopped suddenly in any position stays locked (meaning doesn't rotate under the influence of gravity), as the gear teeth are locked. However, if you choose to use the Helical Bevel gearbox, electo-mechanical brakes may be needed, as the blender cannot stay in a locked position and tries to automatically achieve the neutral position Or the starting position under the influence of gravity.

3. Supports and Bearings/ Plummer Blocks: The shaft of the blender is mostly supported from both the sides by making an A shaped supports with base plate at the bottom (which are either fixed on the ground Or pedestals by means of anchor fasteners Or are grouted). In rare cases (mostly in small capacity blenders) the arrangement can be Cantilever also, where, the blender is just one side supported. Bearing Or Plummer blocks are used to facilitate smooth, jerk free and easy rotation of the blender.

4. Discharge Valve: Bottom Discharge Valves can be Butterfly Valve, as well as, Rotary valve. One has to be careful about the possibility of the powder leakage and ease of unloading while selecting the bottom discharge valve. Valve can be either manual Or pneumatically actuated.

5. Static Baffle: The Octagonal Blender may have a static baffle inside, which can be effective in disturbing the powder layers and relative positioning of powder particles with each other. However, Double Cone Blenders usually doesn't require a static baffle, as anyways there is very good amount of powder mass volume contraction and expansion keeps happening. Another reason for Not recommending a static baffle inside a Double Cone is that the complexity of cleaning the interiors of the Double Cone Blender because of its size, shape and geometry.

6. Vacuum Charging Arrangement: As mentioned above, both Octagonal Blender Or a Double Cone Blenders can be vacuumized to have the feed powder sucked inside the Blender. However, dusting and material wastage are some of the biggest challenges with the Vacuum Charging.

7. Safety Railing and a Proxy sensor Or Limit Switch: Since both of them are rotary equipments, as per the safety guidelines, the safety railing with a interlocking proxy sensor Or limit switch is provided with each of these blenders. Upon opening the safety railing, the blender motor immediately stops and brings the blender to an immediate halt, thus avoiding any possibility of an accident.

ADVANTAGES AND DISADVATAGES OF BOTH THE BLENDERS IN A COMPARATIVE STYLE :

Effectiveness: Both Octagonal, as well as, Double Cone blenders are equally effective. The physical properties of the powder Or mass viz. free flowing nature, moisture content, bulk density and flow patterns adopted by the particles can best decide the most appropriate blender. This study must be done by the process people taking the machine vendor in confidence.
Space occupied: Octagonal blender needs more of horizontal space, whereas, Double Cone requires more of a vertical space Or a headroom.
Batch Size: Practically, the Octagonal Blender is used for handling bigger size batches, then the Double Cone Blender.
Simplicity of Operation: Both the blenders are equally easy and simple in operations. Whether PLC-HMI operated Or Push Button type Panel operated, both are extremely easy to use.
Easy of Automation: Level of automation is mostly Non-Complex Or Straightforward.

MATERIAL OF CONSTRUCTION:

SURFACE FINISH:

In case of GMP setup, Product Contact surface is usually required to be of minimum 240 grit Mirror Finish and Non Contact surface is 180 grit matt finish.

V BLENDER Or V MIXER

2022-02-25T02:18:00.007+05:30

WHAT IS 'V BLENDER':

V Blender is a popular type of a solid - solid (mostly dry powders) blender which works on the principle of diffusion mixing by tumbling action. A closed V shaped container (which has two symmetrical arms forming a V shape) is assembled to rotate between two supports with the help of an AC motor at low RPM, allowing the powder particles to mix under the influence of gravity and tumbling action.

WHERE AND WHY IS IT USED:

V Blenders are popularly used in Pharmaceutical Manufacturing, where various APIs Or Formulation powders needs to be blended. Many a times, V blenders are used in Granulation Process as an alternative to other types of blenders like Double Cone Or Octagonal Blender.

MATERIAL OF CONSTRUCTION:

Since pharmaceutical manufacturing mandates GMP validation, the Contact Parts of the blender usually are made up of SS316 Or Higher Grade, whereas, the Non Contact Parts are made up of SS304. Incase of Highly Corrosive chemicals, the Contact Parts are recommended to be of Hastelloy (C22 Or C276). Halar Coating Or PU Coating may not be possible due to the limited accessibility in the interiors of the V Blender.

SURFACE FINISH:

Product Contact surface is usually required to be of minimum 240 grit Mirror Finish and Non Contact surface is 180 grit matt finish. As mentioned in the earlier blogs, the extremely smooth finish is desired to prevent the surface corrosion due to electrolytic cell formation. Hence, a mirror finish of 240 Or more grit is mandated as per GMP (Good Manufacturing Practice) guidelines.

MAJOR COMPONENTS OF THE V - BLENDER:

1. V Shaped Container Or Shell with closing lids for both the arms: This V shaped vessel constructed has two symmetrical hollow arms forming an Angle Or a V. The bottom of the V has a very small straight vertical cylindrical portion, which has the discharge butterfly valve at the open end Or the bottom end. Whereas, both the arms has closing flanges Or dead plates attached at the open end of each arm by means of a triclover clamp.

2. Drive Assembly: An AC motor along with a suitable Gearbox (mostly hollow shaft) is used for achieving of a low RPM (usually in the range of 10 to 12) without a VFD (Variable Frequency Drive). Note: while choosing the gearbox, one has to keep in mind that the Helical Bevel gearboxes do not have a provision to lock the gears in a stopping position incase of sudden power failure, hence, electo-mechanical brakes may be needed. To avoid this problem, many a times a spur-pinion gear arrangement is used, as it is economical and doesn't need any kind of a brake mechanism.

4. Discharge Valve and Feeding Arrangement: Usually a Butterfly Valve is used as a discharge valve, and is fixed to the open end of the cylindrical part attached to the V. This valve can be either manual Or pneumatically actuated. One can use the same opening for feeding the blender by attaching a bottom feeding vessel (vertical cylindrical vessel with neck flange matching the blender bottom flange). In such a case, the feeder vessel (filled with powder) is attached to the bottom flange of the blender by means of a triclover clamp. Upon attaching, the blender is rotated by180 degrees and a position is achieved, where the V angle comes on the top and the feeder is upside down resting on the V. In this position, the powder falls inside the blender due to gravity. Soon the butterfly valve (which was kept open) is closed, and the blender is rotated back to the original position, so that the feeder comes back on the ground. It is detached from the blender by opening the TC clamp, while, the butterfly valve is off.

5. Intensifier: The intensifier is a special arrangement of an inside protruding high speed chopper (i.e. an assembly of small metal rods welded to the central metal shaft, which is driven by an AC motor coupled with the gearbox). The role of an Intensifier is to facilitate fast and turbulent mixing of the powder in the local zone. While the tumbling action inside the main blender yields a slow and consistent blending, the Intensifier breaks any kind of lumpy situation and ensures that the powder gets vigorously mixed. This also ensure that powder particles (travelling two and fro) gets a push to travel across the blender i.e. from one arm to another, thus creating uniform mixing/ blending.

6. Vaccum Charging Arrangement: Just like an Octagonal Blender Or a Double Cone Blender, V Blender can also be vaccumized and thus powder can be sucked inside the Blender. However, dusting and material wastage are some of the biggest challenges with the Vacuum Charging.

7. Safety Railing and a Proxy sensor Or Limit Switch: Since it is a rotary equipment, as per the safety guidelines, the safety railing with a interlocking proxy sensor Or limit switch is provided with the blender. Upon opening the safety railing, the blender motor immediately stops and brings the blender to an immediate halt, thus avoiding any possibility of an accident.

ADVANTAGES OF A 'V' BLENDER:

Effectiveness: The V blender is more effective as compared with other types of blenders such as Octogonal Blenders, Double Cone Blenders etc. This is so because the powder gets more confined space to travel inside a V blender.
Gravity Advantage due to rotary motion and V type shape: The rotary motion allows very good shuffling and mixing of the powders due to the tumbling action.
Occupies less space as compared with Double Cone Or Octagonal Blender: V blender due to its shape and geometry occupies much lesser space.
Simplicity of Operation: Operating this equipment is no different than operating any other pharmaceutical blender. Whether it is PLC-HMI operated Or Push Button type Panel operated, it is extremely easy to use.
Easy to Automate: Level of automation is mostly Non-Complex Or Straightforward.

CHALLENGES WITH A V - BLENDER:

Cleaning and Maintenance: Due to its shape, size and geometry, it is at times challenging to do washing, cleaning and mechanical maintenance (if any) from inside.
Batch size cannot be very big: Since feeding and unloading a large quantity of the material can be really time consuming, usually smaller size batches (not more than 2000 ltr) are only taken in a V blender.
Design related challenges: If the operating room has height limitations, the capacity too may have limitations.

VIBRO SIFTER AND GYRATORY MOTION

2021-09-04T00:52:00.002+05:30

WHAT IS VIBRO SIFTER OR SIEVE SIFTER:

Vibro Sifter Or Sieve Sifter is one of the most commonly used industrial sieving equipments. It is extremely easy to use, simple in construction and requires minimum maintenance with rare cases of breakdown.

GYRATORY MOTION AND PRINCIPLE OF WORKING OF VIBRO SIFTER:

Vibrosifter makes use of the principle of Gyratory Motion. As per Physics, Angular Momentum (L) for a rotating object is a product of its Moment Of Inertia (I) and its Angular Velocity (w). It can be explained with the help of the Right Hand Principle. However, as per the law of conservation of Angular Momentum (L), if there is no change in the Torque (tou), Or no external torque acts on the object, there is NO change in the Angular Momentum.

Now imagine a situation, where you fix one end of the axis of the spinning object and leave the second end free. Because of the rotary motion, the object has already attained a gyratory state. Now, with the imbalance we created, the plane of rotation of the object starts changing. The object in gyratory motion tries to balance the situation by changing the direction of the angular momentum (Note: Angular momentum is a vector quantity and can be shown by the right hand thumb as per the fig above), such that, the object starts rotating around the point where the axis is fixed.

Vibrosifter uses gyro motor Or vibratory motor, which creates this kind of imbalance, hence, the plate above the motor shaft tries to attain the gyratory motion. However the number of springs attached to a fixed support ensures the plate and all the decks above do not rotate of go far from the original position, resulting into continuous vibrations.

MAJOR COMPONENTS OF VIBROSIFTER:

1. Top Charging Lid: The topmost nozzle is provided for feeding the material to be sieved.

2. Mesh or Screen: Depending on the number of deck, the screens Or meshes of different aperture are fixed to the bottom of each deck. Due to continuous vibrations, the material particles of lower size passes through the mesh and oversize material either stays above the mesh or can flow out from the side discharge nozzle.

3. Discharge Nozzles: Each deck has a discharge nozzle which facilitates the discharge of the material which has already passed through the mesh from the previous Or top deck.

4. TC Clamps: Tri-Clover Or quick release clamps are provided to hold the two adjacent decks together. In order to avoid the leakage of the powder through the clamps, PP Or Food Grade Silicon gaskets are used on the edges of the deck

5. Bottom housing plate and Springs: The plate is attached to the fixed supports with the help of the metal springs.

6. Vibro Motor - A special purpose eccentric shaft AC powered motor is used to generate gyratory motion in the plate above it.

7. Metal Structure: The structure supports the sifter body with the help of the metal springs and does not pass the vibrations to the floor below.

MATERIAL OF CONSTRUCTION:

Incase of Pharmaceutical and Food applications, the Contact Parts are SS316 Or superior, whereas, the Non Contact are SS304. Incase of non corrosive chemicals, the Contact Parts can be SS304 and Non COntact parts can be MS + Epoxy painted also.

SURFACE FINISH:

ADVANTAGES OF VIBROSIFTER:

1. Various Sizes available: Vibrosifter can be available in sizes ranging from lab scale model to large diameters viz 72 inches Or 6 feet.

2. Economical: Sifter only consumes the electrical power for running the motor. No other ancillary equipments Or resources are needed. Hence, it is economical in nature.

3. Minimum Downtime Or Maintenance needed: Apart from the gaskets of TC clamps, no other part of sifter gets damaged usually. Infact, this is one of those rare equipments that can run 24 X 7 without breakdowns.

4. Screens and Meshes can be replaced based on requirement: Various sizes of meshes Or screens can be kept in spares and can be used as per the need.

5. Can be integrated with other equipments in the granulation line: Usually Vibrosifters are used in line with Multimill or Comill or sometimes with RMG or FBD also.

Please feel free to contact me regarding any questions, queries Or additional assistance needed on Design, Sales, Qualification or other aspects at shg.techo@gmail.com

CONICAL BLENDER DRYER (WITH DOUBLE HELICAL RIBBON)

2021-08-21T22:59:00.003+05:30

CONICAL BLENDER - DRYER WITH DOUBLE HELICAL RIBBON:

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As the name suggests, this equipment consists of a vertical conical vessel with a top entry agitator, which has the conical shaped double helical ribbon welded to. The vessel, as well as, the ribbon is limpeted. With circulation of hot utility (viz. Hot Water Or Low Pressure Steam) through the limpet and the ribbon, the wet mass can be heated to evaporate the solvent Or moisture and with vacuum application, the vapors of solvent Or water can be recovered by condensation.

Drawing ref: RAHI ENGenius Solutions LLP, Ankleshwar

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WORKING PRINCIPLE:

Conical Dryer-Blender works on the principle of Vacuumized Drying. The water Or solvent in the wet mass evaporates due to the heated body, shaft and the limpet. The vapors generated are extracted and condensed by the external heat exchanger and vacuum application. Low rpm rotation of the helical ribbons (which is limpted too) continuously shuffle the mass from bottom to top. The overall efficiency is much higher than any static vacuumized dryer, as the rate of heat transfer is high. On the other hand, Conical Blender can be used merely for blending operations also.

ADVANTAGES:

Multipurpose (i.e. Dryer cum Blender): The Helical Ribbons are designed in such a way that the wet powder mass travels to and fro between vertically i.e. between two ends of the shaft. Incase of Drying, this helps in excellent heat transfer. In case of only Blending, this helps in thorough mixing in minimum time.
Gravity Advantage due to Vertical and Conical shape: Both charging and discharging of the powder mass is easy, as, material has to follow the gravitational flow. For bottom discharge, suitable control valve (either knife gate valve Or zero hold up ball valve) is provided.
Recommended for Large Batches and Minimum Human Exposure: This equipment is more recommended for Chemical applications (i.e. Non Pharma applications), as, it can handle bigger production batches (say several tons). Material charging can done with the help of vacuum or pneumatic conveying too.
Simplicity of Operation: Operating this equipment is no different than operating a reactor. Mostly this can be mounted on lug supports such that if top dish and distillation assembly is on one floor, the material discharge will be on the floor below.
Provision of Solvent Recovery: Solvent recovery rate is very high, as compared with other Or traditional vacuum dryers.
Easy to Automate: Level of automation is mostly Non-Complex Or Straightforward
Choice of MOC (Material of Construction): This equipment is generally not used in Pharmaceutical preparations. However, if required, the material of construction can be SS316 Or Hastelloy Or Halar/ PU/ PFA coated SS304. This can take care of the corrosive material and its vapors.

CHALLENGES WITH VERTICAL CONICAL DRYER -BLENDER:

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Cleaning and Maintenance: The inside body is occupied with the limpted double helical ribbon set. That makes it difficult in washing, cleaning and doing mechanical maintenance (if any).
Bottom Holdup i.e. some quantity of mass may remain unstirred Or undried: The bottom most part of the ribbons is designed to lift the material upwards during operation. However, due to the conical shape of the vessel, as well as, nature of the bottom valve used, there may be chances of material hold-up Or material accumulation at the bottom, which can lead to non-uniform mixing and drying in that particular area only.
Design related challenges: Circulation of the Hot Utilities such as Hot Water Or LPS (low pressure steam) through the ribbons, shaft and the vessel limpet can be challenging.
Not Recommended for Pharma Applications: The QC guidelines used in Pharma industries doesn't permit inaccessibility of the contact parts, as cleaning and sterilization (if any) can be a big concern. Also, the batches in Pharma -API are not very big usually. Therefore, this kind of an equipment is not used in pharmaceutical drying.

MAJOR COMPONENTS OF THE CONICAL DRYER-BLENDER:

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1. Vertical Conical Shell with Limpet and Insulation and Top dish: This vertical conical limpeted vessel is designed to handle both large quantity of mass under high temperature and vacuum. The limpet usually covers almost 80% of the height of the vessel. It is further insulated with hot insulation material such as Mineral Wool Or Rock Wool and further cladded. The top dish is designed to take weight of the drive assembly, as well as, has a number of nozzles including the manhole.

2. Vertical Stirrer: A specially designed vertical pipe (either of heavy schedule Or bored out of a solid rod) has double helical ribbon welded to it such that hot utility (both incoming and outgoing) is properly paved Or channeled through it. It is well balanced dynamically, as well as, passes through a suitable Mechanical Seal (fulfilling the vacuum and temperature requirements). As per the required torque calculations, the AC frequency Motor and Gearbox is designed. Usually the final RPM is not more than 8 to 10 rpm. Suitable couplings may be provided inside the vessel, as well as, outside before gearbox in order to protect the drive assembly from damage due to rare case of jamming of ribbons. A soft starter along with VFD (variable frequency drive) is recommended to manage the torque.

3. Double Helical Ribbon Blades: Conically shaped double helical ribbon is manufactured out of stainless steel flats with limpet welded at the bottom with smooth finishing (so that no material deposition should take place). Angle of the helix should be such that bottom to top movement of material should be facilitated.

4. Vacuum Filter Assembly: A vertical cylindrical filter housing mounted on the vacuum nozzle located on the top dish. The filtration assembly includes a course PP filter (say 10 micron) whose objective is to arrest the dried powder particles from going into the condenser Or vacuum pump along with the vapors.

5. Chopper assembly Or Lump Breaker Assembly: A high speed chopping set of blades (rotating at around 200 to 300 rpm) mounted inside of the conical vessel (on the lateral surface) can be optionally provided with a gearbox and an AC frequency motor.

6. Condenser: Typically a Shell and Tube Type Heat Exchanger is used to condense the vapors coming out of the Conical Dryer. Usually the process side fluid (vapors) are passed through tubes, whereas, on the Shell side the utility fluid (mostly chilled water Or cooling water) is circulated. However, it can be the other way around too (depending on the heat load calculations). Condenser can be insulated and cladded for avoiding heat loss to the ambience.

7. Receiver: A solvent recovery receiver is provided at the bottom of the STHE condenser. Receiver can be either Vertical Cylindrical with legs supports Or Horizontal Cylindrical with saddle supports. A vacuum breaking arrangement is provided with a Control/ On-Off valve on the receiver.

8. Vacuum Pump: A suitable capacity Vacuum Pump is connected to the system (mostly to the receiver), which creates vacuum inside the Conical Dryer, and, also facilitates the extraction of the vapors, hence complements the condensation process.

9. Water Heating system Or Low Pressure Steam (for heating the Dryer, Shaft, Ribbon): Incase of a Hot Water System, a dedicated skid mounted vertical cylindrical vessel is provided with external heating i.e. either with steam (LPS) Or with Electrical Heaters. A circulation pump pushes the hot water into the Limpet, and the return water goes back into the Hot Water Generation tank. The level guage/switch on this tank ensure water doesn't spill over, and, make up water valves gets ON when level goes down. The Temperature sensor on the Hot Waters Tank, as well as, sensor on the Inlet of the Limpet coil together controls the flow of Steam (through PID control valve) Or the Electrical Heater, thus ensures the inlet water temperature stays in control. Incase of direct steam heating, the PID valve ensures steam is throttled and uniform temperature is maintained in the limpet.

10. Nitrogen Purging system/ Air Pressure system: A nozzle can be provided with control valve, that can facilitate the intermediate and periodic gushing or N2 gas, which pushes the vapors out towards the condenser. Same nozzle can be used for providing the Air Pressure to facilitate the filtration operation. Vacuum needs to be stopped temporarily while purging.

11. CIP Or Spray Ball arrangement: Optionally, spray balls can be provided on the top dish of the conical shell, which can facilitate cleaning and washing of the main vessel post the batch operation is over.

FACTORS TO BE TAKEN INTO CONSIDERATION WHILE DESIGNING A CONICAL DRYER- BLENDER:

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1. Available Floor Space, Availability of the Utilities and Floor Layout/ Elevation:

Conical Dryer can be either mounted with Legs Or on Lugs supports. In case of a bigger capacity Dryer, the lugs mounting arrangement is recommended, such that, it hangs from a floor with lugs supports. The utility equipments such as Hot Water Tank, Vacuum Pump, Chilled Or Cooling Water, Steam, Nitrogen and Electrical Panel etc must be planned properly for the ease of the operations. As a usual practice all these things are planned simultaneously and in sync with each other. Also, a GAD (General Arrangement Drawing) is superimposed on Autocad Layout Drawing to see the feasibility of installation during the design stage.

2. Material of Construction: MOC selection must be made in accordance with the process parameters.

3. Level of Automation: Depending on the needs of the Production Department and the budget allocation, the level of automation can be decided.

4. Statutory and Safety compliance: Sometimes, due to company policy and FDA mandate, special features are incorporated such as Touch Screen HMI (Human Machine Interface) with PLC (Programmable Logic Control). In some cases, there can be further sophistication by adopting special Data Security measures such as 21 CFR Chapter 11 compliance, which allows password protected individualistic logins and maintains record of each activity by each user. Overall, Safety, GMP guidelines along with respective FDA mandates has to be followed while designing a Dryer.

5. Batch Size Calculations: A basic Process Calculations must be done including Heat Load Calculations. This helps in deciding the optimum batch size, as well as, the time cycle, hence monthly Or timely production throughput.

6. Product Specific Operational Challenges (based on the previous experience Or Studies): Since it is a capital purchase, the careful attention must be given to the specific needs of the Production Team, concerns and apprehensions of the Engineering and Maintenance, as well as, the Safety and Statutory department, which helps ensure the production goes smooth.

7. Mechanical and Process Design, as well as, Sizing of the Equipments: Stress analysis/ calculations must be done under varying parameters such as temperature, vacuum and pressure. Similarly, the thickness calculations must be done keeping in mind the static and dynamic loads.

Please feel free to contact me regarding any questions, queries Or additional assistance needed on Design, Sales, Qualification or other aspects at shg.techo@gmail.com

AGITATED NUTSCHE FILTER DRYER (ANFD)

2021-08-20T02:13:00.016+05:30

WHAT IS ANFD OR AGITATED NUTSCHE FILTER DRYER:

ANFD is one of the most popular Filtration cum Drying equipment. In a typical Pharmaceutical API (Active Pharma Ingredients) production, after the reaction and crystallization stage, a free flowing slurry is formed which needs Filtration as well as Drying in order to produce a dry powder and granules which are free from impurities. To facilitate this, typically two or more small unit operations are carried out, including, Mechanical Filtration using Centrifuge or Filter Press, followed by Vacuum Or other type of Drying. This is highly time consuming, as well as, cumbersome (both ergonomically, as well as, economically). ANFD combines both these operations easily and effectively, thus producing dry cake with minimum moisture Or solvent in it.

Note: Please feel free to visit my blogpost on Lab Scale ANFD for R&D, skid mounted and Pilot Plant Model of ANFD.

WORKING PRINCPLE OF ANFD:

ANFD consists of a vertical cylindrical stirred tank vessel (somewhat looking like a reactor), which has its shell divided into two parts viz. Main Shell and Bottom Shell, which are separated by means of a mesh Or sieve and a filter cloth covering the sieve. The excess water Or solvent from the wet mass is filtered through and collected in the bottom shell, whereas, the remaining major part of the water Or solvent is removed by heating and vacuum drying the wet mass.

In short, the solvent Or water to be removed, is separated and collected at two different places viz.

1. Bottom Shell: through mechanical filtration facilitated by:

(a) Air Pressure in the main shell Or

(b) by agitation created by the vertically adjustable specially designed Agitator Or

2. Vacuum Trap Or Receiver: by means of condensation of solvent/water vapors generated inside the main shell.

MATERIAL OF CONSTRUCTION:

Since Pharmaceutical, Food and even Cosmetics follows GMP guidelines (sometimes due to statutory mandates), usually the Contact Parts are SS316 Or Higher Grade, and Non Contact Parts are SS304. Non - Contact can be of Mild Steel, in case of Non-GMP set up. Incase of Highly Corrosive chemicals, it is highly recommended that the Contact Parts are Hastelloy (C22 Or C276), Or Halar Coated SS304 Or PU/ PFA Coated SS304. Mostly the Metal Sieve is either SS316 Or Hastelloy and is covered with PP filter cloth.

SURFACE FINISH:

MAJOR COMPONENTS OF ANFD:

ANFD is basically is an integrated system consisting of various components. The brief listing and description of them is as follows:

1. Main Shell: This vertical cylindrical and Jacketed/ Limpted vessel is usually constructed larger in diameter and smaller in height. This is so because bigger is the diameter of the vessel, more is the filtration area, and hence, faster is the filtration. The main shell is insulated (and also cladded) with hot insulation material such as Mineral Wool Or Rock Wool.

2. Vertical Stirrer: A low RPM (rotations per minute) stirrer is specially designed to rotate both clockwise, as well as, anticlockwise. A set of hydraulic cylinders are provided on the top dish of the shell to lift the stirrer vertically and bring back down as per the requirement. Stirrer plays extremely important role is sqeezing the wet cake, mother liquor wash, disturbing the cake and in overall filtration and drying.

3. Bottom Shell along with a hydraulic cylinder, Mesh & Filter Cloth: Bottom shell, the vertical cylindrical vessel is nothing but the bottom part of the main shell. Both main shell and the bottom shell has the same diameter, hence are concentric with respect to the vertical axis. The part which separates the two vessels is the Mesh or Sieve or Perforated Plate, which is covered with a Filter Cloth. This mesh is made strong enough so that it can handle the cake weight easily. The filter cloth is usually PP (poly propylene) and is washable/ cleanable. The aperture of the filter cloth is such that it can pass the water/ solvent, however retains the wet cake. The mesh or perforated plate is used to hold and support the filter cloth. Bottom shell has small legs supports with castor wheels. Bottom shell is lifted Or lowered with the help of the hydraulic cylinder. While it is lifted, the special types of clamps hold it fastened to the main shell.

4. Top Dish with Motor, Gear Box, Mechanical Seal, and Hydraulic Cylinders: The top dish is usually torrisperical, however, is designed strong enough to handle the weight of the agitator, lantern and complete drive assembly, seal and coupling, hydraulic cylinders and nozzles and manholes etc. Motor is designed as per the torque calculations. Gearbox is selected accordingly keeping in mind the low rpm (between 6 to 12). Mechanical seal is designed keeping in mind the vacuum requirement, as well as, the temperature.

5. Cake Discharge Nozzle Or Size Discharge Valve with Hydraulic Or Pneumatic Cylinder: The dried cake is discharged through the lateral opening nozzle on the main shell, which opens through a hydraulic Or pneumatic cylinder. The rotating agitator facilitates pushing the cake out towards the discharge valve.

6. Condenser: Typically a Shell and Tube Type Heat Exchanger is used to condense the vapors coming out of the ANFD. Usually the process side fluid (vapors) are passed through tubes, whereas, on the Shell side the utility fluid (mostly chilled water Or cooling water) is circulated. However, it can be the other way around too (depending on the heat load calculations). Condenser can be insulated and cladded for avoiding heat loss to the ambience.

8. Vacuum Pump: A suitable capacity Vacuum Pump is connected to the system (mostly to the receiver), which creates vacuum inside the ANFD, and, also facilitates the extraction of the vapors, hence complements the condensation process.

9. Water Heating system Or Low Pressure Steam (for heating the ANFD main shell Limpet): Incase of a Hot Water System, a dedicated skid mounted vertical cylindrical vessel is provided with external heating i.e. either with steam (LPS) Or with Electrical Heaters. A circulation pump pushes the hot water into the Limpet, and the return water goes back into the Hot Water Generation tank. The level guage/switch on this tank ensure water doesn't spill over, and, make up water valves gets ON when level goes down. The Temperature sensor on the Hot Waters Tank, as well as, sensor on the Inlet of the Limpet coil together controls the flow of Steam (through PID control valve) Or the Electrical Heater, thus ensures the inlet water temperature stays in control. Incase of direct steam heating, the PID valve ensures steam is throttled and uniform temperature is maintained in the limpet.

11. CIP Or Spray Ball arrangement: Optionally, spray balls can be provided on the top dish of the main shell, which can facilitate cleaning and washing of the main vessel post the batch operation is over.

TYPICAL SEQUENCE OF OPERATIONS IN ANFD:

STEP -4 SOLVENT OR ML LIQUID COLLECTION: As mentioned earlier, the solvent or ML can be collected in both bottom shell, as well as, in the receiver.

STEP -5 DISCHARGING OF THE DRIED CAKE: When the cake is dried upto expectations, the vacuum is broken and side discharge valve is opened. The agitator pushes the dry powder towards the discharge valve.

FACTORS TO BE TAKEN INTO CONSIDERATION WHILE DESIGNING AN ANFD:

1. Orientation of ANFD, Available Floor Space, Availability of the Utilities and Floor Layout/ Elevation:

Many a times, project team overlooks the area and space available and later have to regret. Similarly, the utility equipments such as Hot Water Tank, Vacuum Pump, Chilled Or Cooling Water, Steam, Nitrogen and Electrical Panel etc if not planned favorably can cause a lot of trouble such as financial loss due to structural rearrangement work, major construction work and sometimes production time loss too. As a usual practice all these things are planned simultaneously and in sync with each other. Also, a GAD (General Arrangement Drawing) is superimposed on Autocad Layout Drawing to see the feasibility of installation during the design stage.

2. Material of Construction: As mentioned above, the right MOC will decide the adherence to the quality and process parameters, as well as, longevity of the ANFD.

3. Level of Automation: Depending on the needs of the Production Department, as well as, budget allocation, the level of automation can be decided.

AIR TRAY DRYER (ATD) OR TRAY DRYER (TD)

2021-08-09T03:18:00.005+05:30

WHAT IS ATD OR AIR TRAY DRYER:

Air Tray Dryer is the simplest and most economic form of a Static Dryer which works on the principle of Heat Transfer by forced convection. Hot Air is circulated inside a closed cabinet, which help raise the temperature of the wet mass to an extent that the solvent Or water gradually starts getting evaporated and hence forced out of the closed cabinet.

Air Tray Dryer is widely used in all industries including Pharmaceutical (API), Chemicals and Intermediates, Food, Cosmetics etc.

TYPES OF AIR TRAY DRYERS:

Depending on the pattern of air circulation, there can be three popular types of ATDs viz.

1. O Type Flow: Air enters the dryer from the lateral side of the chamber (usually from the lower lateral side) and gets exhausted from the top damper Or exhaust nozzle. The ratio of volume of air exhausted to the volume of air in circulation is 3:10. This type of dryers are also known as a Horizontal flow Tray Dryer. This is the most economic and simplest form of the Tray Dryer and usually doesn't need an inlet AHU. Merely, a simple pre-filter in the inlet is considered to be sufficient. However, if the process demands, HEPA filters might be needed in the inlet. Exhaust AHU can be optional.

2. U Type Flow: Air enters the dryer from the top of the chamber and gets exhausted from the top damper Or exhaust nozzle, taking a U shaped path. If the air inlet point is on the top left, the exhaust would be on the top right and vice-versa. The ratio of volume of air exhausted to the volume of air in circulation is 9:10. This type of dryers are also known as a Vertical Flow Tray Dryer. To facilitate the U shaped path of the Air, the inside wall of the chambers are shaped specifically. Here, usually the inlet air Filtration and Heating are facilitated by external AHU (also known as inlet AHU), which can consist of Pre Filter, Dehumidifier (optional), Steam Coil Or Ele. Heaters, Fine Filter and HEPA Filter (Optional). Exhaust AHU can be purely optional too.

3. W Type Flow: Two stream of air enters the dryer from the two oppositely placed nozzles on the top of the chamber, and gets exhausted from the central damper Or exhaust nozzle on the top, taking a W shaped path. This is also another example of a Vertical Flow Tray Dryer. The ratio of volume of air exhausted to the volume of air in circulation is 9:10 Or 10:10. To facilitate the W shaped path of the Air, the inside wall of the chambers are shaped specifically. Here too, the inlet air Filtration and Heating are facilitated by external AHU (also known as inlet AHU), which can consist of Pre Filter, Dehumidifier (optional), Steam Coil Or Ele. Heaters, Fine Filter and HEPA Filter (Optional). Exhaust AHU can be purely optional too.

PRICIPLE OF WORKING:

ATD Or Air Tray Dryer works on the Principle of 'Heat Transfer by Forced Convection'. Dry air, when passed over a set of Hot Finned Tubed Coils (carrying Low Pressure Steam) Or over Electric Heaters, gets heated up and further removes the moisture Or solvent from the wet mass to be dried. The most important factors to be taken into consideration here are (a) Amount of Heat Required in KCal for drying the wet mass (b) Heat Transfer Area of the Heating Coils (c) Volumetric Flow Rate of the Air required to achieve the desired temperature and (d) Ratio of Volume of Air in circulation to the Volume of Air to be Discharged.

ADVANTAGES OF ATD OR STD OVER OTHER DRYERS:

Most Economic Operation with Minimum Energy Consumption: Air Tray Dryer uses Heat energy provided either by Low Pressure Steam or Electric Heaters. Flow of air is induced with the help of a blower fan operated by AC frequency motor.
Fast Drying with Minimum consumption of Heat Energy: ATDs are operated with Hot Air as a drying media. Because of the recirculation of the hot air inside the Hot Cabinet, the moisture and/or solvents from the wet mass starts evaporating quickly, resulting into fast drying. Due to the interlocking mechanism, the heaters get cut off upon sensor reaching the desired temperature (incase of electrically heated ATD) Or Low Pressure Steam is throttled through PID control valve (incase of the STD or Steam Tray Dryer).
Possibility of De-Humidification: Incase of coastal areas Or area where the Air carries a lot of humidity, an inline de-humidifier can be added in the air suction line Or inlet AHU (inlet Air Handling Unit), which drags the moisture from the Air by condensing it and producing Dry Air (suitable for heating and drying purpose).
Ease of Operation: All the important parts of the ATD viz. Inlet AHU, ATD Chamber, Trolley for Trays, Number of Trays, Ducting (if applicable), Exhaust AHU, Blower Fan etc are all accessible and hence cleanable. Some of the parts like External AHU may require ladder Or operating platform if those are placed at a height.
Minimum Powder Loss Or Maximum Drying Yield: ATD being a static dryer, the powder loss can only be due to handling loss, hence, is controllable. With an Optional Filtration assembly in exhaust (Or AHU in exhaust), the entrained powder particles can be arrested and hence, maximum dry powder is collected by the end of the operation.
Easy availability of Spares, Gaskets and Filters: All of the spares used in ATD are easily available in the market (and also are majorly available in almost all countries where Pharma Production industry exists).
Possibility of fully automated operation with Optional 21 CFR: ATD operations can be made fully automated with HMI and PLC and/or SCADA as per the appropriate Zone Classification, as well as, integration of 21 CFR chapter 11.

DISADVATAGES OR LIMITATIONS OF ATD:

Not Suitable for Air Sensitive Or Hazardous Or Inflammable Products: Certain products due to their properties, cannot withstand direct contact with air Or blow of air. Also, there can be products which are either hazardous Or may have low flash point solvents to be removed. While, there can be some other products which are simply not suitable for ATD. All these products are usually dried under Vacuum.
Not suitable for Too Wet Or Very High density powder particles: Hot Air usually penetrates through the wet cake due to the porous nature of the cake. However, if the cake is too wet, Or, if the bulk destiny of the product is very high, the penetration of the air stays limited, hence, either drying requires very long time, Or ATD is not recommended.
Sheet thicknesses are very low: Cladding over the insulated material is of very thin sheets (usually 18 guage) SS304 Or lower grade Stainless Steel, making is highly vulnerable to mechanical abuse Or impact.
Possibility of frequent Chocking of the HEPA filters: Incase of the exhaust filtration line, the series of filters usually includes Pre Filter (10 micron), Fine Filter (5 or 3 micron) and HEPA filter (0.3 micron). Many products in the later stages of drying generates highly fine particles, which easily escapes the Pre and Fine filter and get arrested by HEPA. This can lead to frequent chocking of the HEPA filter, and might need frequent replacements.
Inlet and Exhaust AHU (Optional) needs bigger space: The space needed for suction Air Handling Unit as well as Exhaust Air Handling Unit is usually high. Also, the connecting ducting too requires a lot of space. Incase of an Inlet AHU, usually it is placed in the technical area Or non-operational area, whereas the ATD is in the clean room Or operational area. The ducting has to pass through the cleanroom wall. Similarly, the exhaust AHU along with its blower and motor must be kelp outside of the cleanroom and is usually kept in the open space. The ducting sometimes has to travel in a really zigzag fashion, because, many a times the technical area has no space left due to HVAC ducting. One has to keep these challenges in mind when planning the ATD.
Proper Insulation needed for safety purpose, as well as, to avoid heat loss: ATD body, inlet ducting (optional), as well as, sometimes the exhaust ducting (optional) requires proper insulation and cladding (so as to avoid heat loss) as it carries the Hot Air. This is important in both safety point of view, as well as, for preventing the heat losses.

MATERIAL OF CONSTRUCTION:

Since Pharmaceutical, Food and even Cosmetics follows GMP guidelines (sometimes due to statutory mandates), usually the Contact Parts are SS316 Or Higher Grade, and Non Contact Parts are SS304. In some cases, Non - Contact can be of Mild Steel (especially true in case of Non-GMP set up). Further, just like other Process Equipments, incase of Highly Corrosive chemicals, the ATD Contact Parts can be Hastelloy (C22 Or C276), Or Halar Coated SS304 Or PU/ PFA Coated SS304.

SURFACE FINISH:

MAJOR COMPONENTS OF AN ATD:

The major and important components of the ATD can be listed as under:

1. ATD Chamber: The rectangular doubled walled chamber consists of inner 18 guage stainless steel walls which are insulated with LRB or Rockwool insulation and are cladded with external 16 guage steel sheet. Depending on the Type of the dryer (O, U Or W), the inlet and exhaust air points are decided.

2. ATD Door: The chamber door is of the same MOC as that of the chamber. High density Door Gasket (food grade silicon) is fixed on the door, however, it loosens up frequently.

3. Internal trolley with PU wheels: A vertical trolley (mostly SS304 Or SS316) is made up of light weight stainless steel sections. It is designed ergonomically, in such a way that it can hold maximum number of trays (usually 48 trays) and the operator can find it convenient for loading and unloading. Wheels are usually antistatic PU which can withstand high temperature.

4. Trays (for carrying the mass to be dried): Just like the VTD, the trays are usually rectangular open boxes of size 800mm (32)" x 400mm (16)" x 25mm to 30mm (1 or 1½)" with Or without bidding.

5. Recirculation Fans: The Horizontal ATD has a recirculation fan, which pull the air from the filtration air and pushes it into the recirculation loop internally. The motor is always outside of the chamber body, and fan is inside the body.

6. Inlet Filtration and Heating: Depending upon the type of dryer, the nature of the product and process demand, the Inlet Filtration and Heating Coil can be either completely inside of the chamber body (with a lateral partition housing the heating coil and the re-circulation fans) Or can be completely external by means of an Inlet AHU and Ducting.

Components of the Inlet AHU can be further elaborated as under:

A. Inlet AHU Box: The Rectangular AHU box is built in either SS304 Or in Mild Steel. It's components can be described as follows:

B. Pre Filter Assembly: Usually PP Air Filters of mesh size of 10 to 15 microns are used to filter the inlet air and arrest the suspended Or unwanted solid particles.

C. Dehumidification Assembly (Mostly Optional): Incase of Humid Air, the Dehumidifying coils are used with the chilled water Or brine solution circulating from within the coils. This drags and condenses the water Or moisture from the air and makes it dry. The chilled water piping (supply and return line), as well as, the control valve are outside of the AHU.

D. Fine Filter Assembly (Mostly Optional): PP Air Filters of mesh size of 3 to 5 microns are used to filter the inlet air (already passed through the Inlet Filter and/or over the Dehumidifier) and arrest the suspended Or unwanted solid particles (if any).

E. Steam Heated Coil Or Electrically Heated Coil Assembly: Usually Galvanized Steel Tubes Or SS304 Tubes are used to form the coil with fins (welded over the coil) to increase the Heat Transfer Area. The coil carries the Low Pressure steam. When the clean dry air passes over the coil and fins, it gets heated. The temperature of the Hot Air is controlled through the PID operated gate valve.

F. HEPA FIlter (Mostly Optional): Depending on the process requirements, sometimes, the inlet air stream needs to pass through the HEPA filter assembly. However, HEPA filter due to its highly fine mesh ( micron) increases the pressure drop across it and hence the higher capacity suction blower might be needed to create fluidization effect.

G. Ducting (Optional): Inlet Air ducting sometime is needed if the inlet AHU is kept away from the FBD. Usually, Pharma uses either SS304 Or SS316 ducting with Or without insulation.

H. Instrumentation: Instruments like DPG Or DPT (Differential Pressure Guage/ Transmitter), PG/PT (Pressure Guage/ Transmitter), Temperature Indicator/ Transmitter etc are generally mounted on the AHU and forms an important part of the control philosophy.

7. Exhaust AHU: Again, depending upon the type of the dryer, the nature of the product and process demand, the exhaust of the air can be either simply exhausted in the open air Or can be passed through the External AHU and Ducting. Incase, a HEPA filter is used in the exhaust AHU, a separate suction blower along with the differential pressure guage Or transmitter might be needed.

Safety Features and Instrumentation:

The common safety features includes -

A. ATD door sensor and blower/Fan motor interlock

B. Rupture disk and and blower/ Fan motor interlock

C. Differential Pressure Transmitter across the HEPA and sometimes across the Fine filters.

D. Earthing element

Instruments such as PT 100 sensors, PID for steam assembly, FLP Or Non FLP earthing arrangements, Timer, Pressure Gauges/ Transmitters, Temperature Gauges/ Transmitters are used.

Further, the operating panel can be either relay based push button type panel Or HMI (Human Machine Interface) operated PLC (Programmable Logic Control) based panel and can be always suitable to appropriate Zone classification.

FACTORS TO BE TAKEN INTO CONSIDERATION WHILE DESIGNING AN ATD:

1. Orientation of the ATD, Available Floor Space, Availability of the Utilities and Floor Layout/ Elevation: This is one of the most overlooked Or underestimated point. An important point to be noted here is that, ATD can be installed (a) either completely inside the Clean Room Or (b) Only Door and Skirting Frame inside and rest of the body in the Technical Area by passing it through the cleanroom wall. As a usual practice, ATD with its AHUs, Blowers, Ducting etc must be planned in sync with each other. Also, a GAD (General Arrangement Drawing) is superimposed on Autocad Layout Drawing to see the feasibility of installation during the design stage

2. Material of Construction: The appropriate MOC selection is very important with respect to the adherence to the quality and process parameters, as well as, longevity of the ATD.

3. Level of Automation: Depending on the needs of the Production Department, as well as, budget allocation, the level of automation can be decided.

5. Batch Size Calculations: A basic Process Calculations must be done including Heat Load, Drag Force and hence Volumetric Air Flow rate calculations. This helps in deciding the optimum batch size, as well as, the time cycle, hence monthly Or timely production throughput.

7. Mechanical and Process Design, as well as, Sizing of the Equipments: Stress analysis/ calculations must be carried out under varying parameters viz temperature and pressure. Similarly, the thickness calculations must be done keeping in mind the static and dynamic loads.

HOW TO SELECT THE RIGHT ATD MODEL/ ATD VENDOR (Tips and Tricks):

Here are a few tips that will help you choose/ select the most appropriate ATD brand Or Vendor who will manufacture the ATD for you. These tip and suggestions are over and above your Vendor Qualification protocols and procedures, and purely focuses on the Product/ Machine under discussion.

1. Drying Capacity Calculations: As far as possible, we must see to it that the vendor's design fulfills Or matches our calculated container volumes, thicknesses, finger bags area, heat load, blower fan dia and flowrate and other design parameters. If vendor has their own calculations available, we must see and evaluate them on our specifications and requirements.

2. Material of Construction, Quality of Gaskets and Makes of BoughtOuts, Adherance to GMP guidelines: Just like an FBD, ATD too is very a commonly manufactured product and hence a lot of vendors claim to have made outstanding ATDs. Therefore, apart from all other criteria, we must evaluate them on the selection of Material of Construction, Quality of Gaskets and Other BoughtOut items, Aesthetically Pleasing Quality and Surface finish etc. Pharma's requirement of Validation Documentation along with the Test Certificates too is an additional and important parameter.

Please feel free to contact me regarding any questions, queries Or additional assistance needed on Design, Sales, Qualification or other aspects at shg.techo@gmail.com

FLUID BED DRYER OR FLUIDIZED BED DRYER (FBD):

2021-08-05T01:15:00.008+05:30

MEANING OF FBD OR WHAT DOES FBD STAND FOR:

FBD Or Fluid Bed Dryer Or Fluidized Bed Dryer, is considered to be one of the most popular, reliable and economic drying equipments used in Pharmaceutical Granulation process. Apart from granulation, it is also used in Pharma - API production, Chemical and Food industry.

PRICIPLE OF WORKING:

FBD works on the Principle of Fluidization. Fluidization is a phenomenon in which the packed bed of wet powder particles Or particulate solids, when are exposed to a thrust and flow of hot fluid (in this case Hot Air), flowing from the bottom of the bed upwards, forces it to form a flexible bed (which appears like a Bed of Boiling Water), and the bed of floating particulate solids is called as Fluidized Bed. This is achieved because the velocity of the hot air is more than the terminal settling velocity of the particulate solids. In other words, the pressure created by draft of hot fluid (in this case Hot Air) is able to not only balance the weight of (as well as gravitation force exerted by) the wet mass, but also, is able to lift it upwards against the gravitational force.

As per the theory of Fluidization, there can be various stages of fluidization viz. Minimum Fluidization, Smooth Fluidization, Bubbling Fluidization, Turbulent Fluidization, Lean Phase Fluidization etc.

However, for our purpose of Fluidized Bed Drying, the two most important factors to be considered while designing are (a) Minimum Fluidization Velocity, (b) Heat Transfer by Convection (between Hot Air and Wet Particles). Which essentially means that we are merely using the fluidization for the purpose of better area of heat transfer. Hence, the flow rate of Hot Air is chosen accordingly (taking into consideration the wet material properties and the drag force created).

ADVANTAGES OF FBD OVER OTHER DRYERS:

Fast Drying with Minimum Heat: FBDs are usually operated with Hot Air as a drying media. Because of the fluidization, the hot air can easily cover the large surface area of each granule Or powder particle, hence, the drying becomes highly effective in a minimum span of time.
Economic Operation with Minimum Energy Consumption: FBD uses Heat energy provided mostly by Low Pressure Steam or Electric Heaters. Flow of air is induced with the help of a blower fan operated by AC frequency motor. Apart from these, hardly any other sources of energy are needed.
Possibility of De-Humidification: Incase of coastal areas Or area where the Air carries a lot of humidity, an inline de-humidifier can be added in the air suction line Or inlet AHU (inlet Air Handling Unit), which drags the moisture from the Air by condensing it and producing Dry air (suitable for heating and drying purpose).
Ease of Operation: All the important parts of the FBD viz. Inlet AHU, Plenum Chamber, Product Container, Expansion and Retarding Chamber, Filter Bag assembly, Exhaust AHU and blower etc are all accessible and hence cleanable. Some of the parts like Finger Bag assembly and External AHU may require ladder Or other means to access as they are may be placed high.
Minimum Powder Loss Or Maximum Drying Yield: Due to the presence of the Flinger Bag Filters, as well as, optional HEPA filter in exhaust line, the entrained powder particles are arrested and hence, maximum dry powder is collected by end of the operation.
Easy availability of Spares, Gaskets and Filters: All of the spares used in FBD are easily available in the market (and Majorly available in almost all countries where Pharma Production industry exists)
Possibility of fully automated operation with optional 21 CFR: FBD operation can be made fully automated with HMI and PLC and/or SCADA as per the appropriate Zone Classification, as well as, integration of 21 CFR chapter 11.

DISADVATAGES OR LIMITATIONS OF FBD:

Not Suitable for Air Sensitive Or Hazardous Or Inflammable Products: Certain products due to their properties, cannot accept direct contact with air Or blow of air. Also, there can be products which are either hazardous Or may have low flash point of the solvent to be removed. While, there can be some other products which are simply not suitable for FBD. All these products are usually dried under Vacuum.
Not suitable for Too Wet Or Very High density powder particles: It is difficult to create fluidization effect with Too Wet Or Very High Density products (ex. Metal Powders), as they may require very high air thrust and controlling their velocities can be very challenging.
Possibility of frequent Chocking of the HEPA filters: usually, the finger bag are +not less than 10 micron, hence, highly fine particles may escape and get arrested by HEPA. If dryer yields more such fine particles, the HEPA may get chocked and mat need frequent replacements.
May need frequent Finger Bag Cleaning: Usually the pneumatic cylinder attached to the finger bags holder shakes the bags periodically. However, if the powder is sticky Or hygroscopic, there are chances of powder forming sticky layer on the finger bag surface, hence, merely shaking by the pneumatic cylinder may not help.
Inlet and Exhaust AHU needs bigger space: The space needed for suction Air Handling Unit as well as Exhaust Air Handling Unit is usually high. Also, the connecting ducting too requires a lot of space. Incase of an Inlet AHU, usually it is placed in the technical area Or non-operational area, whereas the FBD is in the clean room Or operational area. The ducting has to pass through the cleanroom wall. Similarly, the exhaust AHU along with its blower and motor must be kelp outside of the cleanroom and is usually kept in the open space. The ducting sometimes has to travel in a really zigzag fashion, because, many a times the technical area has no space left due to HVAC ducting. One has to keep these challenges in mind when planning the FBD.
Proper Insulation needed for safety purpose, as well as, to avoid heat loss: FBD inlet ducting, as well as, sometimes the exhaust ducting requires proper insulation and cladding as it carries the Hot Air. This is important in both safety point of view, as well as, for preventing the heat losses.

MATERIAL OF CONSTRUCTION:

Since Pharmaceutical, Food and even Cosmetics follows GMP guidelines (sometimes due to statutory mandates), usually the Contact Parts are SS316 Or Higher Grade, and Non Contact Parts are SS304. Non - Contact can be of Mild Steel, in case of Non-GMP set up. Further, just like other Process Equipments, incase of Highly Corrosive chemicals, the FBD Contact Parts CAN BE Hastelloy (C22 Or C276), Or Halar Coated SS304 Or PU/ PFA Coated SS304. However, usually such expensive metals are not used for fabrication of FBDs, making it an Economic Option.

SURFACE FINISH:

MAJOR COMPONENTS OF A FBD:

For the sake ease, lets review the components in three parts viz.

1. Inlet AHU, and its Ducting

2. FBD with its operating Panel

3. External AHU, and its Ducting

1. Inlet AHU: The Rectangular AHU box is built in either SS304 Or in Mild Steel. It's components can be described as follows:

A. Pre Filter Assembly: Usually PP Air Filters of mesh size of 10 to 15 microns are used to filter the inlet air and arrest the suspended Or unwanted solid particles.

B. Dehumidification Assembly (Mostly Optional): Incase of Humid Air, the Dehumidifying coils are used with the chilled water Or brine solution circulating from within the coils. This drags and condenses the water Or moisture from the air and makes it dry. The chilled water piping (supply and return line), as well as, the control valve are outside of the AHU.

C. Fine Filter Assembly (Mostly Optional): PP Air Filters of mesh size of 3 to 5 microns are used to filter the inlet air (already passed through the Inlet Filter and/or over the Dehumidifier) and arrest the suspended Or unwanted solid particles (if any).

D. Steam Heated Coil Or Electrically Heated Coil Assembly: Usually Galvanized Steel Tubes Or SS304 Tubes are used to form the coil with fins (welded over the coil) to increase the Heat Transfer Area. The coil carries the Low Pressure steam. When the clean dry air passes over the coil and fins, it gets heated. The temperature of the Hot Air is controlled through the PID operated gate valve.

E. HEPA FIlter (Mostly Optional): Depending on the process requirements, sometimes, the inlet air stream needs to pass through the HEPA filter assembly. However, HEPA filter due to its highly fine mesh ( micron) increases the pressure dropo across it and hence the higher capacity suction blower might be needed to creat fluidization effect.

F. Ducting (Optional): Inlet Air ducting sometime is needed if the inlet AHU is kept away from the FBD. Usually, Pharma uses either SS304 Or SS316 ducting with Or witout insulation.

G. Instrumentation: Instruments like DPG Or DPT (Differential Pressure Guage/ Transmitter), PG/PT (Pressure Guage/ Transmitter), Temperature Indicator/ Transmitter etc are generally mounted on the AHU and forms an important part of the control philosophy.

2. FBD with Operating Panel: The major parts of the FBD can be described as under:

A. Plenum Chamber Or Bottom Chamber: The bottom-most part of the FBD assembly, which is connected with the inlet AHU is known as Plenum Or Bottom Chamber. The utility of Plenum Chamber is to ensure the Hot Air is passed upwards through the bed of wet powder in the product container. Plenum chamber is interlocked and sealed with Product Chamber with the help of an inflatable gasket (usually food grade silicon).

B. Product Chamber: The Product Chamber is nothing but a detachable container which has swivel wheel mounted leg supports. Product chamber is taken off to load and unload the wet and dry powder respectively. While, the bottom of the chamber contains a mesh/ perforated sheet for passage of of hot air from the plenum chamber, the top is directly connected to the bottom of the Fluidization Chamber (also known as Expansion Chamber) with the help of a D type hollow tube inflatable gasket.

C. Fluidization- Expansion-Retarding Chamber: Expansion and Finger Bag chamber can be the same, which facilitates Fluidization, as well as, arrests the powder from flowing out by means of the finger bag filters. The fluidization chamber has a inspection window Or a view glass. The bottom of the chamber and the top of product container are sealed by a D type hollow tube inflatable gasket. As a safety measure, the chamber can be provided with rupture disk Or pressure release valve. Also, static charge remover must be attached to the body of the chamber. The chamber also carries a series of finger bags, which are usually Anti Static Polypropylene bags, whose area of cross section, length, diameter and number of fingers etc are decided based on the process data viz amount of air to be dissipated, quantum of the powder to be handled, volumetric flow of air etc.

3. Exhaust AHU: Just like the Inlet AHU, in some cases, there can be an Exhaust AHU required too (box built in either SS304 Or in Mild Steel). The components of Exhaust AHU can be described as follows:

A. Fine Filter Assembly (Mostly Optional): PP Air Filters of mesh size of approx. 3 to 5 microns are used to filter the inlet air (already passed through the Inlet Filter and/or over the Dehumidifier) and arrest the suspended Or unwanted solid particles (if any).

B. HEPA FIlter (Mostly Optional): Depending on the process requirements, the exhaust vapors and hot air streams need to pass through the HEPA filter assembly. HEPA filter due to its highly fine mesh ( 0.3micron) increases the pressure drop across it and hence the higher capacity suction blower might be needed.

C. Ducting (Optional): Exhaust Air ducting is needed whenever the exhaust AHU is kept away from the FBD. Usually, Pharma uses either SS304 Or SS316 ducting with Or without insulation.

D. Instrumentation: Instruments like DPG Or DPT (Differential Pressure Guage/ Transmitter), PG/PT (Pressure Guage/ Transmitter), Temperature Indicator/ Transmitter etc are generally mounted on the AHU. Furhter, solid flow monitor is optionally mounted on the exhaust ducting to identify the leakage Or damage to the finger bags, which can lead to powder loss.

E. Finger Bag cleaning device by shaking them: Finger bags are mounted on a circular stainless steel ring, which has a hooking arrangement of each finger bag. The pneumatic cylinder attached to this ring facilitates the periodic shaking of the rings and hence the fingers and shed the powder blanketing formed on the surface of the finger bags.

Safety Features and Instrumentation:

The common safety features includes -

A. Inflatable gasket and blower motor interlock

B. Rupture disk and and blower motor interlock

C. Differential Pressure Transmitter across the HEPA and sometimes across the Fine filters.

D. Broken Bag detector and Alarm

E. Earthing element

Instruments such as PT 100 sensors, PID for steam assembly, FLP Or Non FLP earthing arrangements, Timer, Pressure Gauges/ Transmitters, Temperature Gauges/ Transmitters are used.

FACTORS TO BE TAKEN INTO CONSIDERATION WHILE DESIGNING A FBD:

1. Orientation of FBD, Available Floor Space, Availability of the Utilities and Floor Layout/ Elevation: This is one of the most overlooked Or underestimated point. As a usual practice, FBD with its AHUs, Blowers, Ducting etc must be planned in sync with each other. Also, a GAD (General Arrangement Drawing) is superimposed on Autocad Layout Drawing to see the feasibility of installation during the design stage.

2. Material of Construction: The appropriate MOC selection is very important with respect to the adherence to the quality and process parameters, as well as, longevity of the FBD.

3. Level of Automation: Depending on the needs of the Production Department, as well as, budget allocation, the level of automation can be decided.

HOW TO SELECT THE RIGHT FBD MODEL/ FBD VENDOR (Tips and Tricks):

Here are a few tips that will help you choose/ select the most appropriate FBD brand Or Vendor who will manufacture the FBD for you. These tip and suggestions are over and above your Vendor Qualification protocols and procedures, and purely focuses on the Product/ Machine under discussion.

2. Material of Construction, Quality of Gaskets and Makes of BoughtOuts, Adherance to GMP guidelines: FBD is otherwise a commonly manufactured products and hence a lot of vendors claim to have made outstanding FBDs, Therefore, apart from all other criteria, we must evaluate them on the selection of Material of Construction, Quality of Gaskets and Other BoughtOut items, Aesthetically Pleasing Quality and Surface finish etc. Pharma's requirement of Validation Documentation along with the Test Certificates too is an additional and important parameter.

Please feel free to contact me regarding any questions, queries Or additional assistance needed on Design, Sales, Qualification or other aspects at shg.techo@gmail.com