Method and system for power production wtih improved efficiency

Patent metadata

Field	Value
Publication number	US-2016010551-A1
Application number	US-201514792728-A
Country	US
Kind code	A1
Filing date	Jul 7, 2015
Priority date	Jul 8, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

The present disclosure relates to systems and methods that provide power generation using predominantly CO 2 as a working fluid. In particular, the present disclosure provides for the use of a portion of the heat of compression from a CO 2 compressor as the additive heating necessary to increase the overall efficiency of a power production system and method.

First claim

1 . A method for heating a recirculating gas stream comprising:
passing a gas stream G at a pressure P 1 and a temperature T 1 through a recuperative heat exchanger such that the gas stream is cooled to a temperature T 2 that is less than T 1 ; separating the gas stream G into a first fraction G 1 and a second fraction G 2 ; compressing the gas stream fraction G 1 to a pressure P 2 that is greater than P 1 ; compressing the gas stream fraction G 2 to a pressure P 3 that is greater than P 1 so as to heat the gas stream fraction G 2 to a temperature T 3 that is greater than T 2 ; withdrawing the heat from the compressed gas stream fraction G 2 ; combining the gas stream fraction G 1 and the gas stream fraction G 2 to form a combined recirculating gas stream G C ; pumping the recirculating gas stream G C to a pressure P 4 that is greater than P 2 and greater than P 3 ; and passing the recirculating gas stream G C to the recuperative heat exchanger such that the gas stream G C is heated by the cooling gas stream G; wherein the heat withdrawn from the compressed gas stream fraction G 2 is added to the recirculating gas stream G C after pumping to pressure P 4 .

2 . The method according to claim 1 , wherein the temperature T 3 is about 100° C. to about 400° C.

3 . The method according to claim 1 , wherein the pressure P 2 of gas stream fraction G 1 and the pressure P 3 of gas stream fraction G 2 are each separately about 40 bar (4 MPa) to about 100 bar (10 MPa).

4 . The method according to claim 1 , wherein the pressure P 4 of the recirculating gas stream G C is about 100 bar (10 MPa) to about 500 bar (50 MPa).

5 . The method according to claim 1 , wherein the mass ratio of gas fraction G 1 to gas fraction G 2 based on the total mass of gas stream G is about 50:50 to about 99:1.

6 . The method according to claim 1 , wherein the recirculating gas stream G C after passing through the recuperative heat exchanger and receiving the heat from the compressed gas fraction G 2 has a temperature T 4 that is within 50° C. of T 1 .

7 . The method according to claim 1 , wherein gas stream fraction G 2 is compressed with multi-stage compression with no intercooling.

8 . The method according to claim 1 , wherein after withdrawing heat from gas stream fraction G 2 , the gas stream fraction G 2 is further compressed before combining with gas stream fraction G 1 .

9 . The method according to claim 1 , wherein the recuperative heat exchanger comprises three heat exchangers or three heat exchange sections in series, such that heat is transferred in a first heat exchanger or heat exchange section operating in temperature range R 1 , a second heat exchanger or heat exchange section operating in temperature range R 2 , and a third heat exchanger or heat exchange section operating in temperature range R 3 with the temperature relationship of R 1 >R 2 >R 3 .

10 . The method according to claim 9 , wherein the gas stream G is separated between the first heat exchanger or heat exchange section and the second heat exchanger or heat exchange section.

11 . The method according to claim 9 , wherein the gas stream G is separated between the second heat exchanger or heat exchange section and the third heat exchanger or heat exchange section.

12 . The method according to claim 9 , wherein the heat withdrawn from the compressed gas stream fraction G 2 is added to the recirculating gas stream G C in one or both of the third heat exchanger or heat exchange section and the second heat exchanger or heat exchange section.

13 . The method according to claim 1 , further comprising adding heat to the recirculating gas stream G C after pumping to pressure P 4 , wherein the added heat is derived from one or both of an air separation unit and a gas turbine.

14 . The method according to claim 1 , further comprising passing the heated recirculating gas stream G C from the recuperative heat exchanger to a combustor that combusts a fuel with oxygen to form a combustion product stream.

15 . The method according to claim 1 , wherein the gas stream G is a turbine exhaust stream.

16 . A method of generating power, the method comprising:
combusting a fuel with oxygen in the combustor in the presence of a recycle CO 2 stream to produce a CO 2 containing combustion stream; passing the CO 2 containing combustion stream through a turbine to expand the CO 2 containing combustion stream, generate power, and form a turbine exhaust stream; withdrawing heat from the turbine exhaust stream; dividing the turbine exhaust stream to form a first turbine exhaust portion and second turbine exhaust portion; separating water from the first turbine exhaust portion to form a main recycle CO 2 stream; compressing the main recycle CO 2 stream; compressing the second turbine exhaust portion to form a heated, compressed second turbine exhaust portion; withdrawing heat from the heated, compressed second turbine exhaust portion; separating water from the cooled, compressed second turbine exhaust portion to form a secondary recycle CO 2 stream; combining the main recycle CO 2 stream and the secondary recycle CO 2 stream to form a combined recycle CO 2 stream; compressing the combined recycle CO 2 stream; heating the combined recycle CO 2 stream with heat withdrawn from the turbine exhaust stream; and further heating the combined recycle CO 2 stream with heat withdrawn from the heated, compressed second turbine exhaust portion.

17 . The method according to claim 16 , wherein the CO 2 containing combustion stream has a temperature of about 500° C. to about 1,700° C. and a pressure of about 100 bar (10 MPa) to about 500 bar (50 MPa).

18 . The method according to claim 16 , wherein the pressure ratio across the turbine is about 5 to about 12.

19 . The method according to claim 16 , wherein the heat is withdrawn from the turbine exhaust stream in a recuperative heat exchanger comprising three or more sections or comprising three or more individual heat exchangers.

20 . The method according to claim 19 , wherein heating the combined recycle CO 2 stream with heat withdrawn from the turbine exhaust stream and further heating the combined recycle CO 2 stream with heat withdrawn from the heated, compressed second turbine exhaust portion is carried out in the recuperative heat exchanger.

21 . The method according to claim 16 , wherein the mass ratio of the first turbine exhaust portion to the second turbine exhaust portion based on the total mass of the turbine exhaust stream is about 50:50 to about 99:1.

22 . The method according to claim 16 , wherein the heat withdrawn from the heated, compressed second turbine exhaust portion is in a temperature range of about 100° C. to about 400° C.

23 . The method according to claim 16 , wherein the main recycle CO 2 stream and the second turbine exhaust portion are independently compressed to a pressure of about 40 bar (4 MPa) to about 100 bar (10 MPa).

24 . The method according to claim 16 , wherein the combined recycle CO 2 stream after heating with heat withdrawn from the turbine exhaust stream and further heating with heat withdrawn from the heated, compressed second turbine exhaust portion has a temperature that is within 50° C. of the temperature of the turbine exhaust stream.

25 . The method according to claim 16 , wherein the second turbine exhaust portion

Assignees

• 8 Rivers Capital Llc

Inventors

• Allam Rodney John
• Forrest Brock Alan
• Fetvedt Jeremy Eron

Classifications

• F25J3/04618

  for cooling an air stream fed to the air fractionation unit · CPC title

• F25J2240/70

  Steam turbine, e.g. used in a Rankine cycle · CPC title

• F02C3/04

  having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16) · CPC title

• F02C3/34 Primary

  with recycling of part of the working fluid, i.e. semi-closed cycles with combustion products in the closed part of the cycle · CPC title

• F25J2230/06

  Adiabatic compressor, i.e. without interstage cooling · CPC title