COMPOUND CLOSED-LOOP HEAT CYCLE SYSTEM FOR RECOVERING WASTE HEAT AND METHOD THEREOF

• US 20110113780A1
• Filed: 11/16/2009
• Published: 05/19/2011
• Est. Priority Date: 11/16/2009
• Status: Active Grant

• Current Assignee: Nuovo Pignone Technologie SRL (Baker Hughes Company)
• Original Assignee: General Electric Company
• Inventors: Lehar, Matthew Alexander
• Granted Patent: US 8,490,397 B2
• Time in Patent Office: Days
• US Class Current: 60/651
• CPC Class Codes: F02C 1/007 combination of cycles
• CPC Class Codes: F02C 1/10 Closed cycles
• CPC Class Codes: F02C 6/18 using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants using waste heat as source of energy for refrigeration plants F25B27/02; using the waste heat of a gasturbine for steam generation or in a steam cycle see F01K23/10

Abstract

A waste heat recovery system includes a Brayton cycle system having an heater configured to circulate carbon dioxide vapor in heat exchange relationship with a hot fluid to heat carbon dioxide vapor. A Rankine cycle system is coupled to the Brayton cycle system and configured to circulate a working fluid in heat exchange relationship with the carbon dioxide vapor to heat the working fluid.

Claims

1. A waste heat recovery system, comprising:

a Brayton cycle system comprising an heater configured to circulate carbon dioxide vapor in heat exchange relationship with a hot fluid to heat carbon dioxide vapor;

a Rankine cycle system coupled to the Brayton cycle system and configured to circulate a working fluid in heat exchange relationship with the carbon dioxide vapor to heat the working fluid.

2. The system of claim 1, wherein the Brayton cycle system comprises a first turbine coupled to the heater and configured to expand the carbon dioxide vapor.

3. The system of claim 2, wherein the Brayton cycle system comprises a first generator coupled to the first turbine and configured to generate power.

4. The system of claim 2, wherein the Rankine cycle system comprises a first heat exchanger, a second heat exchanger, and a third heat exchanger, wherein the carbon dioxide vapor from the first turbine is circulated in heat exchange relationship with the vaporized working fluid sequentially via the first heat exchanger, the second heat exchanger, and the third heat exchanger to heat the working fluid.

5. The system of claim 4, wherein the Brayton cycle system comprises a cooler configured to cool the carbon dioxide vapor fed through the first heat exchanger, the second heat exchanger, and the third heat exchanger.

6. The system of claim 5, wherein the Brayton cycle system comprises a compressor configured to compress the carbon dioxide vapor fed through the cooler.

7. The system of claim 6, wherein the Rankine cycle system comprises a fourth heat exchanger configured to circulate the vaporized working fluid in heat exchange relationship with the carbon dioxide vapor fed from the compressor so as to heat the working fluid.

8. The system of claim 6, wherein the Rankine cycle system comprises a second turbine configured to expand the vaporized working fluid fed from the fourth heat exchanger via the first heat exchanger.

9. The system of claim 8, wherein the Rankine cycle system comprises a second generator coupled to the second turbine and configured to generate power.

10. The system of claim 8, wherein the Rankine cycle system comprises a condenser configured to condense the vaporized working fluid fed from the second turbine via the third heat exchanger.

11. The system of claim 10, wherein the Rankine cycle system comprises a pump configured to pressurize and feed the condensed working fluid from the condenser to the third heat exchanger to vaporize the condensed working fluid.

12. The system of claim 11, wherein a Rankine cycle system comprises a flow splitter device configured to feed one portion of the vaporized working fluid from the third heat exchanger to the fourth heat exchanger and another portion of the vaporized working fluid from the third heat exchanger to a point upstream of the first heat exchanger;

wherein the other portion of the vaporized working fluid from the third heat exchanger is mixed with the vaporized working fluid fed from the fourth heat exchanger to the first heat exchanger.

13. The system of the claim 1, wherein the working fluid comprises hydrocarbon.

14. A method comprising:

circulating carbon dioxide vapor in heat exchange relationship with a hot fluid to heat the carbon dioxide vapor via an heater of a Brayton cycle system;

circulating a vaporized working fluid in heat exchange relationship with the carbon dioxide vapor to heat the vaporized working fluid via Rankine cycle system coupled to the Brayton cycle system.

15. The method of claim 14, further comprising expanding the carbon dioxide vapor via a first turbine coupled to the heater of the Brayton cycle system.

16. The method of claim 15, further comprising generating power via a first generator coupled to the first turbine of the Brayton cycle system.

17. The method of claim 15, further comprising circulating the carbon dioxide vapor from the first turbine in heat exchange relationship with the vaporized working fluid sequentially via a first heat exchanger, a second heat exchanger, and a third heat exchanger of the Rankine cycle system to heat the vaporized working fluid.

18. The method of claim 17, further comprising cooling the carbon dioxide vapor fed through the first heat exchanger, the second heat exchanger, and the third heat exchanger via a cooler of the Brayton cycle system.

19. The method of claim 18, further comprising compressing the carbon dioxide vapor fed through the cooler via a compressor of the Brayton cycle system.

20. The method of claim 19, further comprising circulating the vaporized working fluid in heat exchange relationship with the carbon dioxide vapor fed from the compressor so as to heat the vaporized working fluid via a fourth heat exchanger of the Rankine cycle system.

21. The method of claim 20, further comprising expanding the vaporized working fluid fed through the fourth heat exchanger, the first heat exchanger via a second turbine of the Rankine cycle system.

22. The method of claim 21, further comprising generating power via a second generator coupled to the second turbine of the Rankine cycle system.

23. The method of claim 21, further comprising condensing the vaporized working fluid fed through the second turbine, the third heat exchanger via a condenser of the Rankine cycle system.

24. The method of claim 23, further comprising pressurizing and feeding the condensed working fluid from the condenser to the third heat exchange via a pump of the Rankine cycle system.

25. The method of claim 24, further comprising feeding one portion of the vaporized working fluid from the third heat exchanger to the fourth heat exchanger and another portion of the vaporized working fluid from the third heat exchanger to a point upstream of the first heat exchanger via a flow splitter device of the Rankine cycle system.

26. The method of claim 25, further comprising mixing the other portion of the vaporized working fluid from the third heat exchanger with the vaporized working fluid fed from the fourth heat exchanger to the first heat exchanger.

27. A waste heat recovery system, comprising:

a Brayton cycle system comprising a heater configured to circulate carbon dioxide vapor in heat exchange relationship with a hot fluid from a heat source to heat carbon dioxide vapor;

a Rankine cycle system coupled to the Brayton cycle system and configured to circulate a working fluid in heat exchange relationship with the carbon dioxide vapor and the hot fluid to heat the working fluid.

28. The system of claim 27, wherein the Brayton cycle system comprises a turbine coupled to the heater and configured to expand the carbon dioxide vapor.

29. The system of claim 28, wherein the Rankine cycle system comprises a plurality of heat exchangers, wherein the carbon dioxide vapor from the turbine is circulated in heat exchange relationship with the vaporized working fluid sequentially via the plurality of heat exchangers to heat the working fluid.

30. The system of claim 29, wherein the Brayton cycle system comprises a cooler configured to cool the carbon dioxide vapor fed through the plurality of heat exchangers.

31. The system of claim 30, wherein the Brayton cycle system comprises a multi-stage compressor configured to compress the carbon dioxide vapor fed through the cooler.

32. The system of claim 31, wherein the Brayton cycle system comprises an inter-cooler disposed between a first compressor stage and a second compressor stage and configured to cool the carbon dioxide vapor fed from the first compressor stage to the second compressor stage.

33. The system of claim 27, wherein the heater is further configured to circulate the hot fluid in heat exchange relationship with the vaporized working fluid so as to heat the working fluid.