CHM100 | A Quest

TYPICAL CONDITION WHICH EFFECT GLYCOL LOSSES

noreply@blogger.com (Ali Haider) — Tue, 06 Jun 2017 18:50:00 +0000

Typical Condition Which Effect Glycol Losses

Carryover with outlet gas leaving the contactor.
Leaks at the pump or pipe fittings.
High still overhead temperature.
Contactor column operating at excess gas rates.
Foaming.
Rapid changes in the gas rate.

But
Who do we know if our system operating efficiently or not. Well, we take glycol samples in the field have lab test them, in term of the results then you make the necessary adjustments to reach maximum drying efficiency.
Now we can find out by analyzing the glycol, now it can tell us

Glycol weight percentage
Water content
Hydrocarbon content
Salt contaminant
Solids contaminant
The pH of glycol
Iron content
Foaming tendencies

Glycol weight Percentage
The glycol weight percentage reefer’s to the amount of glycol in the glycol solution also known as glycol purity.

Lean glycol should contain about 98.5 to 99.9% glycol.
Rich glycol content varies about 93 to 96% glycol.

Let’s assume rich glycol sample is in the acceptable range (94.7%) but the lean glycol (97.4%) is outside the acceptable range. This means there may need to be some adjustment made.

Water content

Water content refers to the amount of water in the glycol solution. Low water content in lean glycol is vital to good dehydration. The water content in lean glycol shouldn’t exceed 1.5%. If the water content exceed 1.5%, then re-boiler temperature is too low or heater not working properly. The water content in rich glycol shouldn’t be more than 5 to 6 %.

Water Content Spread

Water content spread referred to the difference in water content between lean and rich glycol, a spread which is too narrow 0.5 to 2% usually means the glycol circulation rate is too high, the rate should be lower to safe energy minimize glycol losses and approve dehydration, a spread over 4 to 6% is too wide usually means circulation rate is too low and should be increased.

Circulation Rate

To remove 1 pounds of water use three gallons of glycol. (11 liters /.45 kilograms)

Hydrocarbon Content

Hydrocarbon content refer to the amount oil paraffin or condensate in the glycol, keep it below 0.1% otherwise problem such as foaming, plugging or foaling will cause glycol loss, import dehydration of the gas. Hydrocarbons get into glycol in two ways.

Hydrocarbons get into glycol by

Condensing in contactor when glycol is colder than incoming gas.
Carryover of hydrocarbons contaminants from inlet separator or gas stream. (If unit have no separator)

Salt Content
Salt content refer to the amount of salt or chloride in the glycol, it should be capped below 0.01% by wt. or 100 ppm. Problems occur when the salt content reaches almost 0.1% by wt. or 1000 ppm.

· Salt build-up

These problems include a build-up of salt on the re-boiler fire tube, resulting in decrease heat transfer efficiency.

· Corrosion

Which will eventually decay the fire tube.

· Hotspot

Hotspot on the fire tube resulting in thermal decomposition of glycol and holes in the fire tube.

Salt usually travels in the gas stream in a fine mist, now if the gas stream contains excessive salt, a filter type separator can be used to remove salt from the gas up-stream of the dehydration unit.

Solid Content
Solid contents referred to the amount of suspended solids in the glycol, suspended solids should be kept below 0.01% by wt. using filtration.

High solid content cause

· Increased pump wear from abrasion.

· Accelerated corrosion and erosion.

· Increased fouling of fire tube.

· Increase glycol loss due to foaming.

· Increased plugging problems.

pH Scale
pH scale referred to the corrosiveness of glycol, pH is a term use to express acidity or alkalinity. It is based on a 0 to 14 scale.

Acidic	Neutral	Alkaline
0 to 6.9	7	7.1 to 14

A pH about 7.3 is consider as save operating level, as glycol pH decreases the equipment corrosion rate increases rapidly and troublesome corrosive compound result. Raising the pH above 8 to 8.5 is not desirable because of more alkaline glycol solution tills to foam and emulsify easily.
Check the pH of glycol periodically and kept on the alkaline side by neutralizing the acid compound with alkaline chemicals.

Iron Content

Iron content referred to the amount of corrosion products in the system. Rust is most common. Corrosion products either come in the incoming gas or they are result of corroding glycol system. If the iron content exceed 10 to 15 ppm than corrosion prevention methods should be consider.

Foaming Tendency

Foaming referred to the foaming tendency of glycol caused by contaminates. These contaminants in the glycol inner the system as gas entrainments water and glycol alone will not cause significant foaming. However the combination of water glycol and oil does create excessive foaming.

Main foaming problems

· Improper gas dehydration

· Excessive glycol losses when glycol foams out of the contactor.

· Equipment problems downstream of contactor from glycol carryover.

Anti-Foam Additives

Foaming problems can temporary be corrected by anti-foam additives which cause the foam to break. The cause of the problem should than be identify and corrected.

Improper use of anti-foam

Improper use of anti-foam additives can cause increase foaming problem.

The best preventer measure against foaming is the installation of properly design inlet gas separator and glycol filtration system, good glycol filter maintenance and pH control are also very important.

OPERATING PRESSURE

noreply@blogger.com (Ali Haider) — Tue, 06 Jun 2017 18:39:00 +0000

Operating Pressure Conditions for Effective Glycol Conditioning and Reduction of Glycol Losses

Now let’s look at operating pressure inthe contactor, re-generator, filters and GCG separator.

Contactor Operating Pressure
If you operate the contactor below the properly design pressure you will have problems.

First, at constant temperature water content of inlet gas increases and pressure decreases, causing the unit work harder to dry the gas.
Secondly, at constant gas rates the gas velocity through the contactor increases as the pressure decreases causing carryover problem.

Regenerator Operating Pressure

Regenerator pressure where build-up If there is plugging or flooding problem in the still packing and increases regenerator pressure prevent some water boiling out of the glycol requiring higher temperature in the re-boiler, this waste fuel gas and also the glycol degradation.

Filter Operating Pressure

As far as filter goes a pressure drop up of 3 to 6 psig is normal and glycol flows through the elements, the pressure increases as the elements become plugged replace the filter elements when this differential pressure increases to 15 to 20 psig.

Gas Condensate Glycol Separator Operating Pressure
Operating pressure in the gas condensate glycol separator is 50 to 85 psig (345 to 587 kpa). Back pressure is maintained by a pressure controlled regulator.
Now that we understand various temperature and pressure into relationships we should able to prevent costly operating problems high glycol losses, foaming and corrosion.
To really operate efficiently we got to minimize our glycol losses, losses occur due to vaporization, entrainment and mechanical leaks.

OPERATING TEMPERATURE

noreply@blogger.com (Ali Haider) — Tue, 06 Jun 2017 18:32:00 +0000

Operating Temperature Conditions for Effective Glycol Conditioning and Reduction of Glycol Losses

First we look at operating temperatures in the contactor, re-boiler and still overhead. Than we look at operating pressures in next post.

Contactor Operating Temperature

In the contactor the temperature of inlet gas and the glycol affect the amount of water removal from the saturated gas. Now if you recall that constant pressure of natural gas can be hold pure water as the temperature the gas increases and what is that mean, well its mean if we keep the inlet gas temperature low the unit will have less water content to remove from the gas. Now you also want to keep the lean glycol temperature down to minimum when entering the contactor but still 10^oF-15^oF (5^oC-7^oC) higher than the inlet gas temperature.

Why? For several reasons,

Advantages of Low Inlet Temperature

Warm glycol absorbs water more easily that hot glycol.
Cool inlet gas has less water in it.
Hydrocarbons condensation is prevented.

Re-Boiler Operating Temperature

Now the re-boiler temperature is important because it controls the concentration of water and lean glycol.

At constant pressure higher re-boiler temperature results in greater glycol purity. The temperature for TEG should be set at 380^oF to 400^oF (193^oC to 204^oC).

Why?

Because we want the range higher than 212^oF (100^oC) temperature where water boils so that water can remove quickly but lower than the temperature of glycol dehydration because 404^oF (207^oC).

Still Column Operating Temperature

Remember what the still column does. It removes water from rich glycol and it recaptures glycol trying to leave with water vapor. The temperature range we want to set for the still over heat temperature is between where water boils and where glycol boils.

Still overhead temperature range between

Higher Than	Lower Than
212^oF (100^oC)	546^oF (286^oC)

It easy because water boils at 212^oF and TEG boils at 546^oF

Importance of Still Column Operating Temperature
The recommended ranges for the still overhead temperature is 212^oF (100^oC) to 215^oF (102^oC) at sea level.

Low still overhead temperature can cause boiler over load and excessive fuel combustion,
High still overhead temperature can cause glycol losses, due to vaporization.

HEAT EXCHANGERS

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 20:41:00 +0000

Heat Exchangers Used in Gas Dehydration Process

These are two types of heat exchanger used to cool the glycol and the glycol dehydration unit.

Glycol to glycol heat exchanger and
Glycol to gas heat exchanger.

Now, lean glycol leave the re-boiler must be cooled proper to entering the contactor the cooling allows to lean glycol to absorb the maximum quality of water from the gas in the contactor. The heat exchanger is very important in the overall operating efficiency of the dehydration unit they substantially reduce the amount of heat required by the re-boiler and allow maximum gas dehydration in the contactor.

The first stage of glycol cooling occurrence the glycol to glycol heat exchanger. This heat exchanger cool the lean glycol coming from surge tank at 400^oF(204^oC) to temperature of 212^oF (100^oC).

The final stage of lean glycol cooling occurrence the glycol to gas heat exchanger. Dry gas leaving the contactor passes through the glycol to gas heat exchanger where cools the incoming lean glycol to a temperature about 10^oF-15^oF (5^oC-5^oC) above than that of natural gas entering the contactor.

On small dehydration units this exchanger often a double pipe heat exchanger which is latterly a pipe within a pipe flows around outlet gas in the inner pipe. Larger units may utilize shell and tube type of heat exchanger (Nandpur Field).

Taking the temperature difference of glycol before and after passing through the heat exchanger tells you what conditions the heat exchanger surface are in, as the exchanger surface becomes more severally foiled the temperature differential across the heat exchanger decreases, means that the exchanger is not efficient as before. When this occurs, you will need more gas to fire the re-boiler.

Individual components that make-up the glycol dehydration unit how the components work together and how the components work together to dehydrate natural gas and to regenerate rich glycol.

SURGE TANK & PUMP

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 20:33:00 +0000

Surge Tank or Accumulator

Now the surge tank store regenerated glycol for pump suction and it is commonly position under the re-boiler. Vapor which are trapped in the surge tank could cause circular pump to vapor lock. Therefore a vent line is provided to remove these vapors from the surge tank.

Pump

Most small dehydration unit used a fluid driven pump (Nandpur Field).
Larger units generally used electrical driven reciprocating pumps in either case.

The pump is a critical part of the unit because it has the only moving part in the system.

Pump Safety

Now before the rich glycol enters the pump it passes through a strainer to remove large particles leaks can be a problem around glycol column pumps. Proper packing land maintance and use the manufacture recommended packing can minimize this problem.

RE-GENERATOR

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 20:12:00 +0000

Re-Generator(Method to Recovered Glycol from Water-Glycol Mixture)

The re-generator is a combination of glycol re-boiler and the still column. They work together to regenerate rich glycol. Making it lean glycol and ready to use in the contactor column.

The re-boilers supply heat to separate glycol and water by simple distillation. Glycol is heated to a temperature between

380℉ to 400℉

(193℃ to 204℃)

to removing up water vapor to regenerate the glycol to 98.5% to 90%. The temperature of TEG should not exceed 400℉ (204℃) because TEG will began to breakdown at higher temperature. Re-boilers can be direct fire (Nandpur Field) or heated by steam or hot oil.

Direct Fire Re-Boiler

Direct Fired Re-boiler type containing a removable fire box and fire tube is normally used and over flow weir maintains the glycol level in the re-boiler excess glycol spills over the weir and flows downward into the surge tank by gravity by passing through Glycol-Glycol Heat Exchanger.

When the glycol level is low in the surge tank fresh glycol is enter to the re-boilers it ran be dried before going into surge tank.

Still Column

The still column or stripper located just above the re-boiler is where the actual distillation of water from glycol takes place. Still column are normally packed column and have thin condensers or reflux coil in the top. These condensers or reflux coil cool water vapors leaving the column and requiring drain glycol. The amount of glycol lost with the water vapor leaving the still column is controlled by the temperature of the water vapor. Now this called the still overhead temperature should be said that boiling point of pure water.

Normally the pressure will be atmospheric 14.7psia at sea level and the temperature will be 212℉(100℃). System operating above sea level, where require low temperature due to lower pressure, systems with back pressure will require higher temperature.

Still Over Head Temperature

If the still overhead temperature is above the boiling of pure water.

Glycol carryover is the result and losses will be higher than normal.

If the still overhead temperature below the boiling point of pour water.

Too much water will condense back into the glycol.

This will cause both re-boiler heat requirements and fuel usage to increase. When the glycol flow rate exceeds maximum design limits a condensation know as column flooding occurs.

Column Flooding

Column flooding is when the still column fill with liquid.

Cause of Column Flooding

This occurs when the glycol being feed to the still column and has a high concentration of light hydrocarbons. These hydrocarbons will distill out of the glycol and condensing the upper portion of the column.

Column flooding does not alloy properly glycol water separation. Rich glycol can be lost to the vent line when the column floods.

FILTERS

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 20:05:00 +0000

Filters Used In Gas Dehydration Process

Filters are installed in the glycol stream to remove solids and other contaminates which may cause plaguing and foams.

Types of Filter

Two types of filter commonly used as a gas dehydration system.

One type is used for solids removal.
Other for dissolved contaminants removal.

For solid removals fine stream shock type or cartridge filter (Nandpur Field) are used.
Now solved particles cause erosion of pump piston valve seals and plugging of equipment and foaming.

Solid Removal (Cartridge or Shock Filters)
Shock filter are commonly used type of solid removal. Shock filter consist cylindrical elements that are replaced as they coated with solids.

Differential Pressure Gauge

A difference pressure gauge measure pressure drop across the element a pressure drop of

3 to 6 psig

(21 to 41 kpa)

is normal as glycol flow through the element the pressure drop increases as the element remove solid material and inversely become plugged.

When pressure diffeerence becomes

15 to 20 psig

(104 to 138 kpa)

The elements should be replaced to prevent stoppage of glycol flow and possible collapse of the elements.

Dissolved Contaminant Removal (Activated Carbon Filters)

For removal of dissolved contaminates activated carbon filters used when the glycol contains measurable quantity of light hydrocarbons. The carbon filter must be change or reactivated frequently. Most glycol systems cannot be operated successfully with carbon absorption.

Now the two types of activated carbon filters.

Small systems like one use a carbon canister with replaceable cartridges.
Large systems use loss fill carbon vessel that use granular activated carbon (Nandpur Field).

When the loss fill vessel is used carbon particles sometimes called fines must be trapped to keep entering the glycol dehydration unit. This is especially important when a fresh carbon bed put into service. Any time the contaminant in the glycol increases. The carbon filter should be replaced. Monthly test should be run to determine the contamination level.

FLASH TANK(Gas Condensate Glycol Separator)

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 19:32:00 +0000

Gas Condensate Glycol Separator (Flash Tank)

The gas condensate glycol separator also known as flash tank or glycol gas separator. Remove gas and liquid hydrocarbons carried out the contactor by the glycol solution. The gas leaves from the top of the vessel and is vented or may be supplement to use the fuel gas required for the re-boiler.

Pressure relief valve

A pressure control valve maintains the back pressure on the vessel usually 50 to 85 psig (345 to 587 kpa) any excess gas is discharge through this back pressure valve.

Advantages of Separating of Hydrocarbons from Glycol

Separating liquid hydrocarbons from glycol before they enter the re-boiler provided several benefits.

Reduce load on carbon filter.
Prevents carbon buildup on the fire tube.
Prevents glycol contamination in glycol still column.

Which can result in flooding, glycol losses and possibly damage to the column.

Control Systems on Flash Tank

Two level control systems are typically installed on flash tank.

The upper system flow of liquid hydrocarbons discharge from the vessel.
The lower system regulates the flow of glycol from the vessel.

CONTACTOR COLUMN (Absorption Column)

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 19:22:00 +0000

Contactor Column

The function of the contactor column, also called absorber, is to remove water vapor from natural gas by physically bringing together. The up flowing natural gas with the down flowing glycol solution. The glycol absorbs the water vapor from the natural gas.

Design Specifications

Contactor column are design to accommodate certain gas volume and pressure, if these design specification are exceeded, then glycol losses and outlet gas dew point will increase.

Contactor column usually contain either

Trays
Random packing
Structural packing

Contactor at Nandpur field contain structure packing. Structure packing is group of core gadded metal sheets welded into a specific pattern and place on edge in the contactor. Glycol coats these sheets and the gas flow between them. This type of packing is more efficient than bubble caps or random packing. Structure is used in columns 6 inch to 10 feet in diameter.

The up flowing gas is force through the structural packing of specific pattern evenly through the flowing glycol. The glycol gives up water and becomes dryer as its passes upward through packing. The glycol becomes more saturated with water as its flow downward.

Nandpur Contactor Column Design Specifications
Size	1000 MM I.D. × 1158 MM S/S
Design	1500 PSIG @ 150^oF
Capacity	50 MMSCFD

Comparison With Trays and Random Packing Systems
Trays	· Usually a tray column consisting of 4 to 12 trays. · This is more expensive than random and structural packing.
Random Packing	· Random packing is metallic, plastic and ceramic. · These structures provided the larger surface area for the glycol solution to spread out and make better contact with the gas. · 4 feet of packing is usually standard and sufficient to achieve the dew point depression up to 13^oC to 18^oC (55^oF to 65^oF). · Channeling is disadvantage of random packing. · Channeling limits the surface area with the glycol and the gas coming poor contact.

Before the lean glycol enters the contactor two things are happen.

The glycol is pumped up to the contactor pressure and
The glycol temperature is lower to within 10 to 15^oC of inlet gas temperature.

Now remember it’s best to have glycol enter the contactor 10 to 15^oC warmer than the inlet gas to eliminate condensation of hydrocarbon vapor.

Mist Eliminator and Glycol Scrubber

Above the column a mist eliminator in the top of contactor for remove any entering glycol

particles in the gas stream that not settle out.

Glycol scrubber is a separate column from the contactor column and it work like mist eliminator. It has two mist eliminators inside.

Advantage of Mist Eliminator

Following are the advantages.

This prevents liquid glycol for being carried out of the contactor and into the gas discharge line commonly referred to carryover.

Carryover Causes

Carryover occurs when glycol contamination causes foam buildup.
Carryover also happens when gas rate is high enough to agitate the liquid on the top tray, so that a foam forms that is too thick for the eliminator to handle.

The gas rate must be reduced to eliminate carryover.

Glycol Level Control

Glycol level control on the contactor is important and stabilizing unit operation.

The level controller should be adjusted to hold the uniform flow rate of glycol out of contactor. It is more important to hold the constant flow of a glycol out and let the glycol level in the contactor and let the glycol level in the contactor vary of few inches, and then hold the constant level in the contactor and let the flow out of fluctuate.

Causes of Flow Rate

Flow rate surges leaving the contactor will cause the re-boiler to operate inefficient and may overload.

Glycol Dehydration Unit Operation

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 19:11:00 +0000

Glycol Dehydration Unit Operation

Glycol Dehydration Unit Operation | Process Flow Diagram

Better dehydration results and significant saving are achieved when dehydration systems are operated properly. Efficiently operated glycol dehydration systems require good understanding of dehydration process, process variables and dew point. We must also understand the operations of the individual components within the system.

Inlet Gas Separator

Let’s start with the inlet separator. The inlet gas stream first enters the gas dehydration unit through an inlet gas separator. Here free liquids are removed, wet gas leave the separator through a mist eliminator. Which eliminate almost all carrier free liquids to the contactor column.

Daily Check-up

The inlet separator should check regularly. Overloading the inlet separator causes excess liquid carrier over into the contactor column which cause foaming. Therefore for proper operation it is important to rotationally monitor liquid levels and there controls.

METHODS TO REMOVE CONTAMINANT

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 19:06:00 +0000

Methods to Remove Contaminant in Natural Gas Dehydration Process

The common natural gas contaminant are

Water
Hydrogen Sulphide
Inert Gases

1. Methods to Remove Water

We remove most of the water with separator at gas head but water vapors in the gas stream are not removed.

These vapors causes hydrate formation; hydrates are combination of hydrocarbons molecules and water.

Disadvantages of Hydrate Formation

Following are the disadvantages of hydrate formation.

That form solid and deposit themselves on pipeline interior, restricting the flow of gas.
Water can also be contribute to corrosion in pipeline.

Dehydration

The process of removing water from substances is called dehydration.

Most common method for dehydrating a natural gas stream.

Liquid desiccator or drying agent called glycol.

Solid bed desiccant ( Molecular sieve)

Methanol Injection

Liquid desiccator or drying agent called glycol.

During this dehydration process glycol absorbs water from gas stream, drying the gas, the glycol in-fact acts as a kind of sponge socking the water out of gas stream. The most glycol dehydration methods use tri-ethylene glycol contactor column or ethylene glycol injection system. At Nandpur gas field tri-ethylene glycol contactor column method is consider.

I am not going in details for these methods, which i am not experiencing in the field.

Solid bed desiccant ( Molecular sieve)

Methanol Injection

2. Methods to remove Hydrogen Sulphide

Hydrogen sulphide which is also known as by its chemical symbol H₂S. Hydrogen sulphide is an acid gas and an acid gas is gas which is forms acid when combine with water.

Acid Gases

Two examples of acid gas are hydrogen sulphide and carbon dioxide.

Nature of Hydrogen Sulphide

Hydrogen sulphide is corrosive and highly toxic gas.
It can be deadly, if proper safety procedures are not following in hydrogen sulphide case.

They are several methods to remove hydrogen sulphide.

Chemical reactions

Ø Amine sweeting

Membrane separation

Batch process

Ø Iron sponge

Ø Zinc oxide

Ø Molecular sieves

Ø Caustic wash

3. Methods to remove Inert Gases

Most common of these gases are carbon dioxide and nitrogen. These and any other noncombustible gases must be removed from the gas stream because it cannot burn and have no heating value. Method varies depend on type of gas being removed.

Caustic waste in the amine process is usually removed carbon dioxide the same way they do hydrogen sulphide.
Nitrogen removed by Nitrogen Rejection Unit (NRU).

INTRODUCTION: NATURAL GAS DEHYDRATION

noreply@blogger.com (Ali Haider) — Sun, 04 Jun 2017 15:51:00 +0000

In August 2014, I got an opportunity to work an an intern in OGDCL Nandpur Gas Dehydration Field.

Nandpur gas dehydration field located in Kabirwala, Punjab between the green fields of cotton and rice alongside the bank of sujjabad canal. This field was got operational in 2005, working with the capacity of 50 MMSCFD. Nandpur field is central gas facility where gas gathered and process. After processing gas goes to Fauji Kabirwala Power Company Limited (FKPCL)

Natural gas is a clean ignition source of fuel and heat for our homes and industries but in order per natural gas to be useful like this, it must undergo many changes on its trip from well to end uses. How natural gas is transformed from its raw stage to useful product.

The natural gas coming out from wells often has too many contaminates, to meet the quality specifications of natural gas buyers, also the gas stream may contain NGL (Natural Gas Liquids) but could have an increase values its separate from the gas stream. So the gas is process to make it more useful and in some cases to make it byproducts, both are marketable.

The natural gas coming out of well is not quality gas, for to meet its quality requirements. It is necessary to pass through several units, which are following

Gas Well
Water Separator
Metering Station
Central Gas Facility
Gas Processing

1. Gas Well

Gas processing is start from the well. Gas is coming out of the ground normally contain fluids such as oil and water but OGDCL Nandpur field face only water. These liquids must remove because the producer concerns the gas.

2. Water Separator

A device used to separate Water from Gas know as separator.

3. Metering Station

After separation gas is pass through orifice meter station by pipeline to the central processing facility. Kneading is a vital link in the process chain because in-order to maximize profits it is critical to know how much gas leaving the well and how much is arriving at the central process facility. A significant difference in those two amounts could indicate a problem, such as leak in pipeline.

4. Central Gas Facility

Now in-order to gas process efficiently, reaches pipe from many producing location to the central gas facility. This is called gas gathering. This gas gathering station can be in where from mile to thousands of mile and link and meet-up pipelines and booster stations that increase the gas pressure as needed to meet the gas at its processing destination. At Nandpur gas field gas reaches from producing location to central gas facility by his own pressure, there is no use of booster.

5. Natural Gas Processing

Gas Processing categorize into two process

• Contaminant removal

• NGL removal (NGL removal method are excluded)

We face contaminants only at Nandpur gas field. Contaminant must be removed in-order to meet pipeline quality specifications. The common natural gas contaminants are

• Water

• H2S

• Inert gases (CO2, N2)

Note: Nandpur gas contains water which should be removed, gas is free of H2S and CO2 is under normal conditions but N2 is about 60-70% average in gas, we ignore this. This has a technical reason.

CHM100 | A Quest

TYPICAL CONDITION WHICH EFFECT GLYCOL LOSSES

Typical Condition Which Effect Glycol Losses

OPERATING PRESSURE

Operating Pressure Conditions for Effective Glycol Conditioning and Reduction of Glycol Losses Now let’s look at operating pressure inthe contactor, re-generator, filters and GCG separator.

Contactor Operating Pressure If you operate the contactor below the properly design pressure you will have problems.

OPERATING TEMPERATURE

Operating Temperature Conditions for Effective Glycol Conditioning and Reduction of Glycol Losses

HEAT EXCHANGERS

Heat Exchangers Used in Gas Dehydration Process

SURGE TANK & PUMP

Surge Tank or Accumulator

Pump

RE-GENERATOR

Re-Generator(Method to Recovered Glycol from Water-Glycol Mixture)

FILTERS

Filters Used In Gas Dehydration Process

FLASH TANK(Gas Condensate Glycol Separator)

Gas Condensate Glycol Separator (Flash Tank)

CONTACTOR COLUMN (Absorption Column)

Contactor Column

Glycol Dehydration Unit Operation

Glycol Dehydration Unit Operation

METHODS TO REMOVE CONTAMINANT

Methods to Remove Contaminant in Natural Gas Dehydration Process

Liquid desiccator or drying agent called glycol.

Solid bed desiccant ( Molecular sieve) Methanol Injection

They are several methods to remove hydrogen sulphide.

Chemical reactions

Membrane separation Batch process

INTRODUCTION: NATURAL GAS DEHYDRATION

Operating Pressure Conditions for Effective Glycol Conditioning and Reduction of Glycol Losses

Now let’s look at operating pressure inthe contactor, re-generator, filters and GCG separator.

Contactor Operating Pressure
If you operate the contactor below the properly design pressure you will have problems.

Solid bed desiccant ( Molecular sieve)

Methanol Injection

Membrane separation

Batch process