Methods and apparatus for high propane recovery

• US 6,601,406 B1
• Filed: 06/19/2002
• Issued: 08/05/2003
• Est. Priority Date: 10/21/1999
• Status: Active Grant

• Current Assignee: Fluor Enterprises Incorporated (Fluor Corporation)
• Original Assignee: Fluor Corporation
• Inventors: Mak, John, Nielsen, Richard B., Deng, Eh
• Primary Examiner(s): CAPOSSELA, RONALD C
• Application Number:
  US10/088,839
• Time in Patent Office: 412 Days
• Field of Search: 626/21, 626/30, 626/31
• US Class Current: 62/621
• CPC Class Codes: C07C 7/005 Processes comprising at least two steps in series
• CPC Class Codes: C07C 7/04 by distillation
• CPC Class Codes: C07C 9/08 Propane
• CPC Class Codes: F25J 2200/04 in a dual pressure main column system
• CPC Class Codes: F25J 2200/72 Refluxing the column with at least a part of the totally condensed overhead gas
• CPC Class Codes: F25J 2200/78 Refluxing the column with a liquid stream originating from an upstream or downstream fractionator column
• CPC Class Codes: F25J 2200/80 using integrated mass and heat exchange, i.e. non-adiabatic rectification in a reflux exchanger or dephlegmator
• CPC Class Codes: F25J 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2210/12 Refinery or petrochemical off-gas
• CPC Class Codes: F25J 2215/64 Propane or propylene
• CPC Class Codes: F25J 2220/68 Separating water or hydrates
• CPC Class Codes: F25J 2240/02 Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2270/02 Internal refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 2270/12 External refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 2270/60 Closed external refrigeration cycle with single component refrigerant [SCR], e.g. C1-, C2- or C3-hydrocarbons
• CPC Class Codes: F25J 3/0209 Natural gas or substitute natural gas
• CPC Class Codes: F25J 3/0219 Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0242 separation of CnHm with 3 carbon atoms or more

Abstract

Methods and configurations for improved propane recovery plant employ an absorber column, and a deethanizer column with an overhead condenser that produces a reflux condensate. The reflux condensate is recycled to both the absorber column and the deethanizer column, and a third recycling loop feeds propane from the absorber column into the deethanizer column in a gaseous form. The overhead condenser employs cold reject gas from the absorber and/or propane as a refrigerant, and preferred deethanizer columns include an integral water removal contactor.

Claims

1. A plant, comprising:

an absorber column that receives an absorber feed gas, and that produces a cold reject vapor and a product fluid;

a second column that receives at least part of the product fluid in a gas form, wherein the second column is further fluidly coupled to a condenser that forms a reflux condensate by using at least part of the cold reject vapor as a refrigerant; and

wherein a first portion of the reflux condensate is recycled into the second column and wherein a second portion of the reflux condensate is fed into the absorber column.

2. The plant according to claim 1 wherein the second column comprises a deethanizer column.

3. The plant according to claim 2 wherein the condenser is an integral overhead condenser.

4. The plant according to claim 2 wherein the condenser employs propane as a refrigerant.

5. The plant according to claim 2 wherein the second column further comprises an integral water removal contactor.

6. The plant according to claim 5 wherein the deethanizer column further receives a wet liquid feed gas.

7. The plant according to claim 5 wherein the integral water removal contactor utilizes triethylene glycol as a dehydrating agent.

8. The plant according to claim 2 wherein the second column further produces a purified product fluid.

9. The plant according to claim 8 wherein the purified product fluid predominantly comprises propane and higher hydrocarbons.

10. The plant according to claim 1 wherein the condenser further receives refrigerant from a turboexpander.

11. The plant according to claim 1 wherein the condenser employs at least in part propane as a refrigerant.

12. The plant according to claim 2 wherein the absorber column is fabricated from stainless steel and the deethanizer column is fabricated from low temperature carbon steel.

13. A plant, comprising:

a feed gas separation element that receives a wet process gas, and that produces a wet gaseous feed gas and a wet liquid feed gas;

a deethanizer column that receives the wet liquid feed gas, wherein the deethanizer column comprises an integral water removal contactor; and

wherein the deethanizer column further comprises an integral overhead condenser that forms a reflux condensate, of which a first portion is recycled into the deethanizer column and of which a second portion is fed into an absorber column.

14. The plant according to claim 13 wherein the feed gas separation element comprises vapor liquid separator.

15. The plant according to claim 13 wherein at least a portion of the wet liquid feed gas is vaporized in the deethanizer column by a reboiler.

16. The plant according to claim 15 wherein at least a portion of the vaporized wet liquid feed gas is dried in the deethanizer column by contacting a triethylene glycol solution.

17. A method of improving the recovery of propane from a feed gas, comprising:

providing an absorber column, and a deethanizer column with an overhead condenser that utilizes at least part of a cold reject vapor from the absorber column as a refrigerant, and wherein the overhead condenser produces a reflux fluid;

forming a first recycling loop in which a first portion of the reflux fluid is recycled into the deethanizer column;

forming a second recycling loop in which a second portion of the reflux fluid is fed into the absorber column; and

forming a third recycling loop in which a product fluid from the absorber is heat exchanged to provide absorber feed gas cooling and fed into the deethanizer column.

18. The method according to claim 17 wherein the deethanizer further comprises an integral water removal contactor.

19. The method according to claim 17 wherein the condenser further employs a propane refrigerant.

20. The method of claim 17 wherein the recovery of propane from a feed gas comprises recovering up to 99 mol % of propane from the feed gas.