Gas Treatment Plant

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Gas Treatment Plant

Chris, Stephanie, Kyle, Mariam

What is Shale gas?

Is natural gas trapped within shale formations.

And why is it important?• Energy dependence • Reduce greenhouse

gas emissions

Purpose

• Take raw shale gas and purify.

• Produce compressed natural gas/pipeline gas.

• Produce liquefied natural gas (LNG)

• Supply methane for Ammonia Plant, Air Separations and Syngas Plant, the Direct Iron Reduction Plant, and Combined Heat/Power plant.

• Supply Nitrogen (N2) to Ammonia Plant.

• Produce natural gas liquids (NGL) for sale.

Shale Gas Composition

Design Basis

First Step:Water Removal and Condensation

Gravity Separation

Example of Horizontal Separator

First Step:Water Removal and Condensation

• Purpose: To separate gas/liquid phases.• Additionally water and NGLs may be

separated within the same unit given proper settling time.

• Proper pressure and liquid-level controls required.

• A mist extractor at gas exit captures droplets too small to settle by gravity.

• The sudden change in momentum generates the separation of liquid from gas.

Second Step:Acid Gas Removal

Second Step: Acid Gas Removal

Amine Treating• Most commonly used process

for removing sour gas in natural gas purification plants

Most Common Amines Used

• Monoethanolamine• Diethanolamine• Methylethanolamine• Diisopropylamine

Pressure Swing Adsorption (PSA)

BenfieldProcess• Thermally regenerated

cyclical solvent process

• Uses an activated, inhibited hot potassium carbonate solution to remove CO2, H2S and other acid gas components

Sulfinol Process

• For selective absorption of H2S, COS and mercaptans, while co-absorbing only part of the CO2

• The solvent is composed of Sulfolane, DIPA or MDEA and water

• Great for treating large quantity of gas such as natural gas which are at elevated pressure

Second Step:Separation H2S and CO2

Second Step:Separation H2S and CO2Room-Temperature Ionic Liquid (RTILs)

• An ionic liquid comprising an anion having a carboxylate function and an effective amount of water is used as an adsorbent to selectively complex the CO2 yielding a gaseous stream with a greatly reduced CO2 content.

Third Step:Separation of H2S and recycle

Claus Process

Scot process

Clauspol process

Fourth Step:Dehydration

Glycol Separation

• Commonly used• Triethylene

Glycol • Glycol absorbs

water• Can potentially

vaporize hydrocarbons

Fifth Step:Nitrogen Removal

Methods: Cryogenics, Pressure Swing Adsorption, Membrane separation and lean oil absorption.

Cryogenics: The only widely acceptable method on the industrial scale.• Costs $0.30-0.50/Mscf for plants handling 75 MMscfd• Costs $1.00+/Mscf for plants handling 2 MMscfd or less.• Methane and Nitrogen condense at different temperatures -

256F and -346F respectively.

Membrane Process: No membrane alone has the Nitrogen/Methane separation characteristics.

PSA and Lean Oil Absorption: Prohibitively high capital costs and require lower volume flows.

Sixth Step:Natural Gas Liquid Recovery

Turbo Expander and Demethanizer

• Turbine through which a high pressure gas is expanded to produce work that is often used to drive a compressor

• Low-temperature distillation column to separate CH4 and Natural Gas Liquids (NGLs)

Seventh Step:Fractionation

Eighth Step:Liquefaction and compression

Eighth Step:Liquefied Natural Gas (LNG) Production

Example of coil-wound LNG heat exchanger

Composition:• Methane 90-95%• Nitrogen 1-4%

• C2+ hydrocarbons 1-5%

• CO2 <1%

LNG Transportation

LNG occupies 1/600th the volume of natural gas in gaseous form.

• LNG is necessary when no pipeline exists.

• Efficient method for exporting natural gas.

Example of LNG tanker

Questions?

Gas Treatment Plant

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