System for enhanced gas turbine performance in a liquefied natural gas facility

Patent metadata

Field	Value
Publication number	US-9841230-B2
Application number	US-55009809-A
Country	US
Kind code	B2
Filing date	Aug 28, 2009
Priority date	Sep 9, 2008
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

A system for liquefying natural gas that includes a process and apparatus for enhancing the performance of one or more gas turbines. Gas turbine power output can be stabilized or even enhanced using the interstage cooling system configured according to one or more embodiments of the present invention. In one embodiment, partially compressed air from a lower compression stage of a gas turbine is cooled via indirect heat exchange with a primary coolant before being returned to a higher compression stage of the same gas turbine. Optionally, the interstage cooling system can employ one or more secondary coolants to remove the rejected heat from the primary coolant system.

First claim

What is claimed is:

1. A process for liquefying a natural gas stream, the process comprising:
(a) cooling at least a portion of the natural gas stream via indirect heat exchange with a first refrigerant in a first refrigeration cycle to produce a cooled natural gas stream;
(b) further cooling at least a portion of the cooled natural gas stream via indirect heat exchange with a second refrigerant in a second refrigeration cycle to provide a further cooled natural gas stream; and
(c) partially compressing an air stream with a low compression stage to provide a partially compressed air stream;
(d) cooling the air stream and the partially compressed air stream via indirect heat exchanger with a primary coolant selected from the group consisting of: the first refrigerant, the second refrigerant, and any combination thereof, to provide a cooled inlet air stream and a cooled partially compressed air stream, wherein the partially compressed air stream is withdrawn from an intermediate compression stage of a gas turbine used to drive at least one refrigerant compressor associated with the first or the second refrigeration cycle, or both; and
(e) introducing the cooled inlet air stream into an inlet of the gas turbine.

2. The process of claim 1 , wherein the cooling step (d) results in a warmed primary coolant stream; further comprising cooling at least a portion of the warmed primary coolant stream via indirect heat exchange with a secondary coolant stream to thereby provide a cooled primary coolant stream and using at least a portion of the cooled primary coolant stream to accomplish at least a portion of the cooling step (d).

3. The process of claim 2 , wherein the secondary coolant stream comprises air.

4. The process of claim 1 , wherein the first and second refrigerants are each comprised predominately of hydrocarbons.

5. The process of claim 1 , wherein the first refrigerant is comprised predominately of propane, propylene, ethane, or ethylene.

6. The process of claim 1 , wherein the first refrigerant is comprised predominately of propane.

7. The process of claim 6 , wherein the second refrigerant is a mixed hydrocarbon refrigerant.

8. The process of claim 6 , wherein the second refrigerant is comprised predominately of ethane, ethylene, methane, or nitrogen.

9. The process of claim 1 , wherein the cooling of step (d) cools the partially compressed air stream to a temperature that is at least 1° C. cooler than the temperature of an uncompressed air stream being supplied to the inlet of the gas turbine.

10. The process of claim 1 , wherein the partially compressed air steam and the air stream are cooled in a common heat exchanger.

11. The process of claim 1 , wherein the gas turbine is dual-shaft or triple-shaft gas turbine.

12. The process of claim 11 , wherein the gas turbine is a triple-shaft gas turbine.

13. The process of claim 12 , wherein the first refrigerant is predominately comprised of propane, wherein the second refrigerant is a mixed hydrocarbon refrigerant.

14. The process of claim 13 , further comprising cooling at least a portion of the further cooled natural gas stream in a third refrigeration cycle, wherein the third refrigeration cycle comprises a nitrogen refrigeration cycle.

15. The process of claim 1 , further comprising cooling at least a portion of the further cooled natural gas stream in a third refrigeration cycle, wherein the third refrigeration cycle comprises and open-loop methane refrigeration cycle.

16. The process of claim 1 , further comprising, intermediate to step (b), separating at least a portion of the cooled natural gas stream in a heavies removal column to provide a predominately methane overhead product and a heavies-rich bottom product, wherein the further cooled natural gas stream comprises at least a portion of the predominately methane overhead product.

17. The process of claim 1 , wherein the first and the second refrigerants are pure-component refrigerants, wherein the first and second refrigerants have different compositions.

18. The process of claim 1 , further comprising introducing the cooled partially compressed air stream to a high compression stage of the gas turbine.

19. A process for liquefying a natural gas stream, the process comprising:
(a) compressing a first refrigerant stream in a first refrigerant compressor to provide a first compressed refrigerant stream, wherein the first refrigerant compressor is at least partially driven by a first gas turbine;
(b) compressing a first air stream with a low compression stage to provide a partially compressed air stream;
(c) cooling the partially compressed air stream via indirect heat exchange with at least a portion of the first compressed refrigerant stream to provide a first cooled air stream and a cooled partially compressed air stream; and
(d) introducing at least a portion of the first cooled air stream into the first gas turbine.

20. The process of claim 19 , further comprising cooling a second air stream via indirect heat exchange with the first refrigerant to provide a second cooled air stream and introducing the second cooled air stream into first gas turbine, wherein the second air stream is an uncompressed air stream, wherein the second cooled air stream is introduced into the low compression stage of the first gas turbine.

21. The process of claim 19 , further comprising cooling a second air stream via indirect heat exchange with the first refrigerant to provide a second cooled air stream and introducing the second cooled air stream into a second gas turbine used to power a second refrigerant compressor operable to compress a second refrigerant system.

22. The process of claim 21 , wherein the first and the second refrigerant streams have different compositions.

23. The process of claim 22 , wherein the first and the second refrigerant streams are comprised predominately of hydrocarbons.

24. The process of claim 21 , wherein the first refrigerant stream comprises predominately propane, wherein the second refrigerant stream comprises predominately ethylene, ethane, nitrogen, or methane.

25. The process of claim 24 , further comprising using at least a portion of the first and the second refrigerant streams to cool the natural gas stream to provide a cooled natural gas stream and further cooling the cooled natural gas stream via indirect heat exchange with a third predominately methane refrigerant.

26. The process of claim 21 , wherein the first refrigerant is comprised predominately of propane, wherein the second refrigerant is a mixed hydrocarbon refrigerant.

27. The process of claim 19 , wherein the cooling step (b) cools the first air stream by no more than 25° C., wherein none of the cooling of step (b) is accomplished via direct heat exchange.

28. The process of claim 19 , wherein the first gas turbine is a multi-shaft gas turbine.

29. The process of claim 19 , further comprising introducing the cooled partially compressed air stream to a high compression stage of the gas turbine.

30. A liquefied natural gas (LNG) facility, the LNH facility comprising: a first refrigeration cycle comprising a first refrigerant compressor, a first refrigerant chiller, and a first gas turbine, wherein the first refrigerant compressor is operable to produce a compressed first refrigerant stream and the first refrigerant chiller

Assignees

• Masani Karl D
• Meher-Homji Cyrus B
• Conocophillips Co

Inventors

• Masani Karl D
• Meher-Homji Cyrus B

Classifications

• F25J1/021

  using a deep flash recycle loop · CPC title

• F25J2220/64

  Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general · CPC title

• F25J1/0283

  Gas turbine as the prime mechanical driver · CPC title

• F01D15/005

  Adaptations for refrigeration plants · CPC title

• F25J1/0052 Primary

  by vaporising a liquid refrigerant stream · CPC title