Combined cycle waste heat recovery system

• US 5,813,215 A
• Filed: 02/21/1995
• Issued: 09/29/1998
• Est. Priority Date: 02/21/1995
• Status: Expired due to Fees

• Current Assignee: Arthur M. Weisser
• Original Assignee: Arthur M. Weisser
• Inventors: Weisser, Arthur M.
• Primary Examiner(s): Freay, Charles G.
• Application Number:
  US08/392,374
• Time in Patent Office: 1,316 Days
• Field of Search: 60/39.15, 60/39.161, 60/39.181, 60/655
• US Class Current: 60/39.181
• CPC Class Codes: F02C 6/003 Gas-turbine plants with heaters between turbine stages
• 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
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

A waste heat recovery system (WHRS) and combined cycle power plant (CCPP) uses waste heat from an open cycle gas turbine primary stage having a combustion chamber for generating heated exhaust gas. A primary turbine is driven by the heated exhaust gas. A generator is driven by the primary turbine. A primary compressor is driven by the primary turbine for pressurizing the heated exhaust gas for driving the primary turbine. A first closed cycle helium turbine stage incorporates a first closed helium loop. A first heat exchanger (HX) is coupled between the hot exhaust gas from the open cycle gas turbine primary stage and the first closed helium loop for transferring heat to the first closed helium loop. A first turbine is driven by the helium heated in the first closed helium loop. A generator is driven by the first turbine. A first compressor in the first closed helium loop upstream from the first HX pressurizes helium gas through the first HX for driving the first turbine. A second heat exchanger is provided downstream in the first closed helium loop from the first turbine. At least one intermediate closed cycle helium turbine stage similarly constructed is coupled to the first stage through the second HX. Preferably there are several intermediate stages coupled in series. A final closed cycle helium turbine stage has a final closed helium loop. A final HX coupled in the final closed helium loop downstream from the final turbine transfers heat to a heat sink. The secondary closed cycle helium turbine stage can be coupled in a variety of series and parallel configurations.

Claims

1. A waste heat recovery system for generating electricity from hot exhaust fluid of a power plant open cycle primary stage, said waste heat recovery system and power plant open cycle primary stage forming a combined cycle power plant, said waste heat recovery system comprising:

a plurality of n secondary closed cycle circulating gas turbine stages coupled in series, each stage n comprising an nth closed circulating azeotropic gas loop filled with circulating gas having a high specific heat and a high thermal conductivity and an nth heat exchanger in the closed circulating gas loop, said nth heat exchanger being coupled between the (n-1)th closed circulating gas loop of the (n-1)th closed cycle circulating gas turbine stage and the nth closed circulating gas loop of the nth closed cycle circulating gas turbine stage for transferring heat to circulating gas in the nth closed circulating gas loop;

each closed cycle circulating gas turbine stage comprising an (n+1)th heat exchanger coupled between the nth closed circulating gas loop of the nth closed cycle circulating gas turbine stage and the (n+1)th closed circulating gas loop of the (n+1)th closed cycle circulating gas stage for transferring heat to circulating gas in the (n+1)th closed circulating gas loop;

each closed cycle circulating gas turbine stage n also comprising an nth turbine in the nth closed circulating gas loop downstream from the nth heat exchanger and upstream from the (n+1)th heat exchanger, a generator driven by the nth turbine, and a circulating gas compressor driven by the nth turbine, said circulating gas compressor being coupled in the nth closed circulating gas loop for pressurizing circulating gas in the nth heat exchanger for driving the nth turbine;

said n stages comprising a first closed cycle circulating gas turbine stage having a first closed circulating gas loop and a first heat exchanger coupled between the hot exhaust fluid of the power plant open cycle primary stage and the first closed circulating gas loop for transferring waste heat to circulating gas in the first closed circulating gas loop upstream from a first turbine;

and said n stages comprising a last closed cycle circulating gas turbine stage having a last closed circulating gas loop, and a last heat exchanger coupled in the last closed circulating gas loop downstream from a last turbine for transferring heat to a heat sink.

2. The waste heat recovery system of claim 1 wherein the power plant open cycle primary stage is an open cycle gas turbine primary stage having a combustion chamber for generating heated exhaust gas, a primary turbine driven by the heated exhaust gas, a generator driven by the primary turbine, and a primary compressor driven by the primary turbine for pressurizing the heated exhaust gas for driving the turbine;

and wherein the heated exhaust fluid of the power plant open cycle primary stage is the heated exhaust gas of the open cycle gas turbine primary stage.

3. The waste heat recovery system of claim 2 wherein the first heat exchanger is a gas to gas heat exchanger.

4. The waste heat recovery system of claim 3 wherein the heat exchangers of the waste heat recovery system are plate type heat exchangers.

5. The waste heat recovery system of claim 1 wherein the circulating gas filling the respective closed circulating gas loops is selected from the group consisting of helium, argon, xenon, neon, carbon dioxide, and nitrogen.

6. The waste heat recovery system of claim 7 wherein the circulating gas filling the respective closed circulating gas loops is a gas mixture of gases selected from said group.

7. The waste heat recovery system of claim 1 wherein the circulating gas filling the respective closed circulating gas loops is helium.

8. The waste heat recovery system of claim 1 comprising a plurality of at least five secondary closed cycle circulating gas turbine stages coupled in series.

9. The waste heat recovery system of claim 1 comprising a plurality of at least three secondary closed cycle circulating gas turbine stages.

10. The waste heat recovery system of claim 1 wherein the heat sink coupled to the last heat exchanger is a cooling tower.

11. The waste heat recovery system of claim 1 wherein the turbines of the respective stages n are coupled to a common shaft for driving the same shaft and same generator.

12. The waste heat recovery system of claim 1 wherein the turbines of the respective stages n are coupled to different shafts for driving multiple shafts and multiple generators.

13. The waste heat recovery system of claim 1 comprising a second set of a plurality of m secondary closed cycle circulating gas turbine stages coupled in series as set forth in claim 1, said second set of a plurality of m secondary closed cycle circulating gas turbine stages being coupled in parallel with the plurality of n secondary closed cycle circulating gas turbine stages to the hot exhaust fluid of the power plant open cycle primary stage.

14. A combined cycle power plant comprising:

an open cycle gas turbine primary stage having a combustion chamber for generating heated exhaust gas, a primary turbine driven by the heated exhaust gas, a generator driven by the primary turbine, and a primary compressor driven by the primary turbine for pressurizing the heated exhaust gas for driving the primary turbine;

a first closed cycle helium turbine stage having a first closed helium loop, a first heat exchanger coupled between the hot exhaust gas from the open cycle gas turbine primary stage and the first closed helium loop for transferring heat to the first closed helium loop, a first turbine driven by the helium heated in the first closed helium loop, a generator driven by the first turbine, a first compressor in the first closed helium loop upstream from the first heat exchanger for pressurizing helium through the first heat exchanger for driving the first turbine, and a second heat exchanger downstream in the first closed helium loop from the first turbine;

at least one intermediate closed cycle helium turbine stage comprising a second closed helium loop, said second heat exchanger being coupled between the first closed helium loop and the second closed helium loop for exchanging heat from the first closed helium loop to the second, a second turbine downstream from the second heat exchanger, a generator driven by the second turbine, a second compressor driven by the second turbine for pressurizing helium gas in the second heat exchanger, and a third heat exchanger in the second closed helium loop downstream from the second turbine;

and a final closed cycle helium turbine stage having a final closed helium loop, a next to last heat exchanger coupled between an intermediate closed helium loop of an intermediate closed cycle helium turbine stage and the final closed helium loop for transfer of heat to the final closed helium loop, a final turbine driven by the helium heated in the final closed helium loop, a generator driven by the final turbine, a final compressor driven by the final turbine for pressurizing helium in the next to last heat exchanger for driving the final turbine, and a final heat exchanger coupled in the final closed helium loop downstream from the final turbine for transferring heat to a heat sink.

15. The combined cycle power plant of claim 14 comprising a heat sink coupled to the final heat exchanger and wherein said heat sink is a cooling tower.

16. The combined cycle power plant of claim 14 comprising a plurality of at least five closed cycle helium turbine stages coupled in series.

17. The CCPP of claim 16 wherein the turbines of the respective primary stage and helium turbine stages are coupled to a common shaft for driving the same shaft and same generator.

18. The combined cycle power plant of claim 14 wherein the turbines of the respective primary stage and helium turbine stages are coupled to different shafts for driving multiple shafts and multiple generators.

19. A combined cycle power plant comprising:

an open cycle power plant primary stage generating heated exhaust fluid;

a first secondary closed cycle circulating gas turbine stage having a first closed circulating gas loop having an azeotropic gas, a first heat exchanger coupled between the hot exhaust fluid from the open cycle power plant primary stage and the first closed circulating gas loop for transferring heat to the first closed circulating gas loop, a first turbine driven by the circulating gas heated in the first closed circulating gas loop, a generator driven by the first turbine, and a first compressor in the first closed circulating gas loop upstream from the first heat exchanger for pressurizing circulating gas through the first heat exchanger for driving the first turbine, and a second heat exchanger downstream in the first closed circulating gas loop from the first turbine.

20. The combined cycle power plant of claim 19 comprising:

a plurality of n secondary closed cycle circulating gas turbine stages coupled in series, each stage n comprising an nth closed circulating gas loop filled with circulating gas having a high specific heat and a high thermal conductivity and an nth heat exchanger in the closed circulating gas loop, said nth heat exchanger being coupled between the (n-1)th closed helium loop of the (n-1)th closed cycle circulating gas turbine stage and the nth closed circulating gas loop of the nth closed cycle circulating gas turbine stage for transferring heat to circulating gas in the nth closed circulating gas loop;

each closed cycle circulating gas turbine stage comprising an (n+1)th heat exchanger coupled in the nth closed circulating gas loop between the nth closed circulating gas loop of the nth closed cycle circulating gas turbine stage and the (n+1)th closed circulating gas loop of the (n+1)th closed cycle circulating gas stage for transferring heat to circulating gas in the (n+1)th closed circulating gas loop;

each closed cycle circulating gas turbine stage n also comprising an nth turbine downstream in the closed circulating gas loop from the nth heat exchanger and upstream from the (n+1)th heat exchanger, a generator driven by the nth turbine, and a circulating gas compressor driven by the nth turbine, said circulating gas compressor being coupled in the nth closed circulating gas loop for pressurizing circulating gas in the nth heat exchanger for driving the nth turbine.

21. The CCPP of claim 20 comprising a last closed cycle circulating gas turbine stage having a last closed circulating gas loop, and a last heat exchanger coupled in the last closed circulating gas loop downstream from a last turbine for transferring heat to a heat sink.

22. The combined cycle power plant of claim 19 comprising:

a plurality of n secondary closed cycle circulating gas turbine stages coupled in parallel to the first stage, each stage n comprising an nth closed circulating gas loop filled with circulating gas having a high specific heat and a high thermal conductivity and an nth heat exchanger in the closed circulating gas loop, said nth heat exchanger being coupled between the heated exhaust fluid of the power plant primary stage and the nth closed circulating gas loop of the nth closed cycle circulating gas turbine stage for transferring heat to circulating gas in the nth closed circulating gas loop;

each closed cycle circulating gas turbine stage comprising a second heat exchanger coupled in the nth closed circulating gas loop for transferring heat;

each closed cycle circulating gas turbine stage n also comprising an nth turbine downstream in the closed circulating gas loop from the nth heat exchanger and upstream from the second heat exchanger, a generator driven by the nth turbine, and a circulating gas compressor driven by the nth turbine, said circulating gas compressor being coupled in the nth closed circulating gas loop for pressurizing circulating gas in the nth heat exchanger for driving the nth turbine.

23. The combined cycle power plant of claim 22 wherein the turbines of the respective stages n are coupled to a common shaft for driving the same shaft and same generator.

24. The combined cycle power plant of claim 22 wherein the turbines of the respective stages n are coupled to different shafts for driving multiple shafts and multiple generators.

25. The combined cycle power plant of claim 24 wherein the circulating gas filling the respective closed circulating gas loops is helium.

26. The combined cycle power plant of claim 22 comprising an additional plurality of secondary closed cycle circulating gas turbine stages coupled in series with the plurality of parallel coupled n secondary closed cycle circulating gas turbine stages.