Configurations and methods of high pressure acid gas removal in the production of ultra-low sulfur gas

Patent metadata

Field	Value
Publication number	US-10384160-B2
Application number	US-201715697238-A
Country	US
Kind code	B2
Filing date	Sep 6, 2017
Priority date	Feb 17, 2010
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

Acid gas is removed from a high pressure feed gas that contains significant quantities of CO2 and H2S. In especially preferred configurations and methods, feed gas is contacted in an absorber with a lean and an ultra-lean solvent that are formed by flashing rich solvent and stripping a portion of the lean solvent, respectively. Most preferably, the flash vapors and the stripping overhead vapors are recycled to the feed gas/absorber, and the treated feed gas has a CO2 concentration of less than 2 mol % and a H2S concentration of less than 10 ppmv, and more typically less than 4 ppm.

First claim

What is claimed is:

1. A plant for acid gas removal from a feed gas, comprising:
an absorber configured to receive a vapor stream derived from the fed gas and to produce a treated gas, wherein the absorber is further configured to separately receive a first portion of a lean physical solvent and an ultra-lean physical solvent and to produce a rich physical solvent;
a flash regeneration section fluidly coupled to the absorber and configured to receive the rich physical solvent and to produce the lean physical solvent from the rich physical solvent;
a stripping column fluidly coupled to the flash regeneration section and configured to receive a second portion of the lean physical solvent, to receive a portion of the treated gas as a stripping gas, and to produce the ultra-lean physical solvent from the second portion of the lean physical solvent;
a first conduit coupled to the flash regeneration section and configured to provide the first portion of the lean physical solvent to the absorber; and
a second conduit coupled to the stripping column and configured to provide the ultra-lean physical solvent to the absorber.

2. The plant of claim 1 , wherein the flash regeneration section comprises a plurality of flash vessels, and a plurality of conduits configured to combine vapors from the plurality of flash vessels, a stripping column overhead product, and a dry gas stream to form the feed gas.

3. The plant of claim 2 , wherein the flash regeneration section comprises,
a first hydraulic turbine coupled between the absorber and a first flash vessel of the plurality of flash vessels; and
a second hydraulic turbine coupled between the first flash vessel of the plurality of flash vessels and a second flash vessel of the plurality of vessels.

4. The plant of claim 1 , further comprising:
a third conduit coupled to the stripping column and configured to provide a stripping column overhead product to the absorber.

5. The plant of claim 1 , further comprising:
a chiller and separator coupled to the absorber and configured to chill the feed gas to a temperature that is sufficient to condense and separate C5+ hydrocarbons from the feed gas and to produce the vapor stream.

6. The plant of claim 1 , wherein the stripping column is further configured to contact the second portion of the lean physical solvent and the portion of the treated gas within the stripping column.

7. The plant of claim 1 , wherein the absorber is configured to receive the first portion of the lean physical solvent and the ultra-lean physical solvent at different positions along the absorber.

8. The plant of claim 1 , further comprising a JT valve, wherein the JT valve is configured to receive the portion of the treated gas and to expand the portion of the treated gas prior to the portion of the treated gas being received by the stripping column.

9. The plant of claim 2 , wherein the plurality of flash vessels are fluidly coupled in series.

10. The plant of claim 2 , further comprising:
a heat exchanger, wherein the heat exchanger is configured to heat a flashed liquid stream obtained from one of the plurality of flash vessels using the feed gas or the lean physical solvent.

11. The plant of claim 1 , wherein the absorber is configured to receive the first portion of the lean physical solvent at a point below a point at which the ultra-lean physical solvent is received.

12. The plant of claim 1 , further comprising:
a first heat exchanger configured to chill the feed gas to a temperature that is sufficient to condense C5+ hydrocarbons in the feed gas; and
a separator coupled to the absorber and configured to separate the C5+ hydrocarbons from the feed gas to produce the vapor stream.

13. The plant of claim 12 , further comprising:
a second heat exchanger configured to heat a flashed liquid stream obtained from the flash regeneration section using the feed gas.

14. The plant of claim 13 , further comprising:
a third heat exchanger configured to heat an absorber overhead product using the feed gas.

15. The plant of claim 12 , further comprising:
a second heat exchanger configured to heat a flashed liquid stream obtained from the flash regeneration section using the lean physical solvent.

16. The plant of claim 12 , wherein the absorber is configured to receive the vapor stream in a lower section thereof.

17. The plant of claim 1 , wherein the flash regeneration section comprises:
a first plurality of flash vessels configured to produce a flashed liquid stream and a plurality of flashed vapor streams; and
a second plurality of flash vessels configured to receive the flashed liquid stream and to produce a CO 2 -containing flash gas and the lean physical solvent; and
a first heat exchanger configured to heat the flashed liquid stream using the feed gas.

18. The plant of claim 17 , wherein the flash regeneration section further comprises:
a plurality of conduits configured to combine the plurality of flashed vapor streams, a stripping column overhead product, and a dry feed gas stream to form the feed gas.

19. The plant of claim 17 , further comprising:
a second heat exchanger configured to chill the feed gas to a temperature that is sufficient to condense C5+ hydrocarbons in the feed gas; and
a separator coupled to the absorber and configured to separate the C5+ hydrocarbons from the feed gas to produce the vapor stream.

20. The plant of claim 17 , wherein the first plurality of flash vessels comprises three flash vessels fluidly coupled in series, and wherein the second plurality of flash vessel comprises two flash vessels fluidly coupled in series.

Assignees

• Fluor Tech Corp

Inventors

• Mak John

Classifications

• B01D2252/20431

  Tertiary amines · CPC title

• B01D2252/2023

  Glycols, diols or their derivatives · CPC title

• B01D53/1425 Primary

  Regeneration of liquid absorbents · CPC title

• B01D53/1462

  Removing mixtures of hydrogen sulfide and carbon dioxide · CPC title

• B01D2252/2021

  Methanol · CPC title