1. Novel Method for Gas Separation
By: Chris Wilson
For: Senior Capstone 2008

2. Overview
Current process
New process
Economic comparison

3. Natural Gas Processing The Way it is Done
Current process
Remove excess water
Remove acid gas
Dehydrate
Remove mercury
Remove nitrogen
Separate NGL (ethane, and heavier hydrocarbons)

4. Natural Gas Processing Everything Together

5. Water removal Removes free liquid water and condensate gas
Sends the gas to a refinery
The water goes to waste

6. Natural Gas Processing Everything Together

7. Natural Gas Processing Acid Gas Removal
Hydrogen sulfide
Mercaptans
Carbon dioxide
Acid gas removal processes
Amine treating
Benfield process
Sulfinol process
others

8. Natural Gas Processing Amine Treatment
Most common used amines
Monoethanolamine
Diethanolamine
Diisopropylyamine
Methylethanolamine
Hydrogen sulfide goes through a Claus process
64,000,000 metric tons of sulfur are produced from this process

9. Natural Gas Processing Amine Treating

10. Natural Gas Processing Sulfinol 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
Sulfolane, a clear colerless liquid, developed by shell in the 1960’s

11. Natural Gas Processing Sulfinol Process

12. Natural Gas Processing Everything Together

13. Natural Gas Processing Glycol Dehydration
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

14. Natural Gas Processing Glycol Dehydration
Wet gas enters a contacting tower at the bottom. Dry glycol flows down the tower from the top, from tray to tray, or through packing material. A bubble cap configuration maximizes gas/glycol contact, removing water to levels below 5 lbs/MMscf. Systems can be designed to achieve levels down to 1lb/MMscf. The dehydrated gas leaves the tower at the top and returns to the pipeline or goes to other processing units. The water rich glycol leaves the tower at the bottom, and goes to the reconcentration system. In the reconcentration system, the wet glycol is filtered of impurities and heated to 400°F. Water escapes as steam, and the purified glycol returns to the tower where it contacts wet gas again.

15. Pressure Swing Adsorption
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

16. Natural Gas Processing

17. Mercury removal 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

18. Natural Gas Processing

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

20. Natural Gas Processing Cryogenic Process
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

21. Natural Gas Processing Lean Oil Removal
Lean oil is fed countercurrent with the wet gas
Temperature and pressure are set to allow for the greatest absorption of unwanted gases
In the ambient lean oil absorption process the natural gas is contacted with the lean oil (molecular weight of about 150) in an absorber column at the ambient temperature of about 100°F. The rich oil exiting the bottom of the absorber flows into a rich oil depropanizer (ROD) which separates the propane and lighter components and returns them to the gas stream. The rich oil is then fractionated in a still, where the NGL's (C4+) are recovered as an overhead product and the lean oil is recycled to the absorber column. Typically, 75 percent of butanes and percent of pentanes and heavier components are recovered. In the refrigerated lean oil absorption process, the lean oil is chilled against propane refrigerant to improve the recovery of propane to the 90 percent level, and depending upon the gas composition, up to 40 percent of ethane may be recovered (Elliot, 1997). Since reducing the molecular weight of lean oil enhances the lighter component absorption and an external refrigerant is used to chill the lean oil, 100 to 110 molecular weight lean oils are generally used in this process.

22. Natural Gas Processing Membranes
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

23. Natural Gas Processing Economics

24. Demethanizer

25. Demethanizer 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

26. Natural Gas Processing Cryogenic Process

27. NGL recovery

28. NGL recovery Now the rest of the liquid is fed to three units Process
Deethanizer
Debutanizer
Depropanizer
Process
Each sent to a distillation column

29. Sweetening NGL’s

30. Merox Processes Mercaptan oxidation Removes mercaptans from Propane
Butane
Larger hydrocarbons

31. Natural Gas Processing Another Process

32. Novel Method
Technical information momentarily not available due to IP issues
However economics will be compared
If you want the access to this, then talk to OTD

33. Novel Method 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
If you want the access to this, then talk to OTD

34. Novel Method

35. Current Method

36. Economics - Amine Treating

37. Amine Treating - Simulation

38. Economics - Demethanizer

39. Demthanizer - Simulation

40. Economics - Dethanizer

41. Deethanizer - Simulation

42. Economics

43. Built in Error