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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
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
Second Step:Acid Gas Removal
Pressure Swing Adsorption (PSA)
Second Step:Acid Gas Removal
BenfieldProcess• Thermally regenerated
cyclical solvent process
• Uses an activated, inhibited hot potassium carbonate solution to remove CO2, H2S and other acid gas components
Second Step:Acid Gas Removal
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 CO2
Room-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
Third Step:Separation of H2S and recycle
Claus Process
Third Step:Separation of H2S and recycle
Scot process
Third Step:Separation of H2S and recycle
Clauspol process
Fourth Step:Dehydration
Fourth Step:Dehydration
Glycol Separation
• Commonly used
• Triethylene Glycol
• Glycol absorbs water
• Can potentially vaporize hydrocarbons
Fifth Step:Nitrogen Removal
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
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
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?