Novel Method for Gas Separation - PowerPoint PPT Presentation

Novel Method for Gas Separation

By: Chris Wilson

For: Senior Capstone 2008

• Current process
• New process
• Economic comparison

• Current process
• Remove excess water
• Remove acid gas
• Dehydrate
• Remove mercury
• Remove nitrogen
• Separate NGL (ethane, and heavier hydrocarbons)

• Removes free liquid water and condensate gas
• Sends the gas to a refinery
• The water goes to waste

• Hydrogen sulfide
• Mercaptans
• Carbon dioxide
• Acid gas removal processes
• Amine treating
• Benfield process
• Sulfinol process
• others

• Most common used amines
• Monoethanolamine
• Diethanolamine
• Diisopropylyamine
• Methylethanolamine
• Hydrogen sulfide goes through a Claus process

• Used to reduce H2S, CO2, and mercaptans from gases
• Great for treating large quantities of gas
• Solvent absorbs the sour gas
• Sulfolane is used

• Method for removing the water vapor from the gas
• Usable glycols
• Triethylene glycol –

most commonly used

• Diethylene glycol
• Ethylene glycol
• Tetraethylene glycol
• Works by having the glycol adsorb the water

• Adsorbent material is used
• Gas and material go under high pressure
• Material adsorbs the gas ( H2S, mercaptans, CO2)
• Disadvantages
• Requires high pressures
• Slow cycle times

• Current Processes
• Activated carbon – through chemisorption. Activated has extremely high surface area
• Mercury can damages aluminum heat exchangers
• Those used in cryogenic processing plants
• Those use in liquefaction plants

• Processes that can reject nitrogen
• Cryogenic process
• Absorption process (using lean oil or solvent)
• Membrane separation
• Adsorption process (activated carbon)

• Common refrigerants used
• Most common method for removal of impurities such as nitrogen
• Disadvantages
• Must reach extremely low temperatures
• Only useful for large scale production

• Lean oil is fed countercurrent with the wet gas
• Temperature and pressure are set to allow for the greatest absorption of unwanted gases

• Driving force
• Partial pressure
• Type of material determine permeability

D = diffusion coefficient (cm2/s)

k = Henry’s law sorption coefficient (cm3/cm3cmHg)

P1 = Permeability of component 1

P2 = Permeability of component 2

• The next step is to recover the NGL’s
• Process
• Cryogenics using a turbo-expander can be used
• This is the most common
• Lean oil adsorption can be used here

• Now the rest of the liquid is fed to three units
• Deethanizer
• Debutanizer
• Depropanizer
• Process
• Each sent to a distillation column

• Mercaptan oxidation
• Removes mercaptans from
• Propane
• Butane
• Larger hydrocarbons

• Technical information momentarily not available due to IP issues
• However economics will be compared

• Advantage
• More cost effective than any previous methods
• Less environmental impacts than previous methods
• Separates all contaminants
• Separates each component
• Everything is done using one process