Method and apparatus for implementing a thermodynamic cycle

• US 5,649,426 A
• Filed: 04/27/1995
• Issued: 07/22/1997
• Est. Priority Date: 04/27/1995
• Status: Expired due to Fees

• Current Assignee: Wasabi Energy Limited
• Original Assignee: Exergy S.P.A.
• Inventors: Pelletier, Richard I., Kalina, Alexander I.
• Primary Examiner(s): Husar, Stephen F.
• Assistant Examiner(s): Basichas, Alfred
• Application Number:
  US08/429,706
• Time in Patent Office: 817 Days
• Field of Search: 60/649, 60/673
• US Class Current: 60/649
• CPC Class Codes: F01K 25/065 with an absorption fluid remaining at least partly in the liquid state, e.g. water for ammonia F01K5/00 takes precedence

Abstract

A method and apparatus for implementing a thermodynamic cycle. A heated gaseous working stream including a low boiling point component and a higher boiling point component is expanded to transform the energy of the stream into useable form and to provide an expanded working stream. The expanded working stream is then split into two streams, one of which is expanded further to obtain further energy, resulting in a spent stream, the other of which is extracted. The spent stream is fed into a distillation/condensation subsystem, which converts the spent stream into a lean stream that is lean with respect to the low boiling point component and a rich stream that is enriched with respect to the low boiling point component. The lean stream and the rich stream are then combined in a regenerating subsystem with the portion of the expanded stream that was extracted to provide the working stream, which is then efficiently heated in a heater to provide the heated gaseous working stream that is expanded.

Claims

1. A method of implementing a thermodynamic cycle comprising

expanding a heated gaseous working stream including a low boiling point component and a higher boiling point component to transform the energy of said stream into useable form and provide an expanded working stream,

splitting said expanded working stream into a first expanded stream and a second expanded stream,

expanding said first expanded stream to transform its energy into useable form and provide a spent stream,

feeding said spent stream into a distillation/condensation subsystem and outputting therefrom a first lean stream that is lean with respect to said low boiling point component and a rich stream that is enriched with respect to said low boiling point component,

combining said second expanded stream with said lean stream and said rich stream to provide said working stream, and

adding heat to said working stream to provide said heated gaseous working stream.

2. The method of claim 1 further comprising heating said first working stream prior to said expanding said first working stream.

3. The method of claim 1 wherein said lean stream and said rich stream that are outputted by said distillation/condensation subsystem are fully condensed streams.

4. The method of claim 3 wherein said combining includes first combining said first lean stream with said second expanded stream to provide an intermediate stream, and thereafter cooling said intermediate stream to provide heat to preheat said rich stream, and thereafter combining said intermediate stream with said preheated rich stream.

5. The method of claim 4 wherein said intermediate stream is condensed during said cooling and is thereafter pumped to increase its pressure and is preheated prior to said combining with said preheated rich stream using heat from said cooling of said intermediate stream.

6. The method of claim 5 wherein said first lean stream is preheated using heat from said cooling of said intermediate stream prior to mixing with said second stream.

7. The method of claim 5 further comprising generating a second lean stream in said distillation/condensation subsystem, combining said second lean stream with said spent stream in said distillation/condensation subsystem to provide a combined stream, and condensing said combined stream by transferring heat to a low temperature fluid source.

8. The method of claim 7 further comprising separating at least part of said combined stream in said distillation/condensation subsystem into an original lean stream used to provide said first and second lean streams and an original enriched stream used to provide said rich stream, wherein said original enriched stream is in the form of a vapor, said original lean stream is in the form of a liquid, and said separating is carried out in a separator in said distillation/condensation subsystem.

9. The method of claim 8 further comprising splitting said combined stream in said distillation/condensation subsystem into a first combined stream portion that is separated into said original lean stream and said original enriched stream and a second combined stream portion, and mixing said second combined stream portion with said original enriched stream to provide said rich stream.

10. The method of claim 9 wherein said rich stream is condensed in said distillation/condensation subsystem by transferring heat to said low temperature fluid source and is pumped to increase its pressure.

11. The method of claim 10 wherein said original enriched stream is cooled by transferring heat to preheat and partially vaporize said at least part of said combined stream prior to separating in said separator.

12. The method of claim 11 wherein said original enriched stream is cooled by transferring heat to preheat said rich stream.

13. The method of claim 1 further comprising generating a second lean stream in said distillation/condensation subsystem, combining said second lean stream with said spent stream in said distillation/condensation subsystem to provide a combined stream, and condensing said combined stream by transferring heat to a low temperature fluid source.

14. The method of claim 13 further comprising separating at least part of said combined stream in said distillation/condensation subsystem into an original lean stream used to provide said first and second lean streams and an original enriched stream used to provide said rich stream.

15. The method of claim 14 further comprising splitting said original lean stream in said distillation/condensation subsystem to provide said first and second lean streams.

16. The method of claim 14 wherein said original enriched stream is in the form of a vapor, said original lean stream is in the form of a liquid, and said separating is carried out in a separator in said distillation/condensation subsystem.

17. The method of claim 16 wherein said original enriched stream is cooled by transferring heat to preheat and partially vaporize said at least part of said combined stream prior to separating in said separator.

18. The method of claim 14 further comprising splitting said combined stream in said distillation/condensation subsystem into a first combined stream portion that is separated into said original lean stream and said original enriched stream and a second combined stream portion, and mixing said second combined stream portion with said original enriched stream to provide said rich stream.

19. The method of claim 18 wherein said rich stream is condensed in said distillation/condensation subsystem by transferring heat to said low temperature fluid source and is pumped to increase its pressure.

20. The method of claim 18 wherein said original enriched stream is cooled by transferring heat to preheat said rich stream.

21. The method of claim 20 wherein said second lean stream is cooled prior to said combining with said spent stream by transferring heat to said first combined stream portion.

22. The method of claim 20 wherein said spent stream is cooled prior to said combining with said second lean stream by transferring heat to said first combined stream portion.

23. Apparatus for implementing a thermodynamic cycle comprising

an first gas expander connected to receive a heated gaseous working stream including a low boiling point component and a higher boiling point component and to provide an expanded working stream, said first gas expander including a mechanical component that transforms the energy of said heated gaseous stream into useable form as it is expanded,

a stream splitter connect to receive said expanded working stream and to split it into a first expanded stream and a second expanded stream,

a second gas expander connected to receive said second expanded stream and to provide a spent stream, said second gas expander including a mechanical component that transforms the energy of said second expanded stream into useable form as it is expanded,

a distillation/condensation subsystem that is connected to receive said spent stream and converts it to a first lean stream that is lean with respect to said low boiling point component and a rich stream that is enriched with respect to said low boiling point component,

a regenerating subsystem that is connected to receive and combine said second expanded stream, said first lean stream, and said rich stream, and outputs said working stream, and

a heater that is connected to receive said working stream and adds heat to said working stream to provide said heated gaseous working stream.

24. The apparatus of claim 23 further comprising a reheater for heating said first working stream prior to said expanding said first working stream at said second expander.

25. The apparatus of claim 23 wherein said distillation/condensation subsystem outputs said lean stream and said rich stream as fully condensed streams.

26. The apparatus of claim 25 wherein said regenerating subsystem includes a first junction at which said first lean stream and said second stream are combined to form an intermediate stream, a first heat exchanger that transfers heat from said intermediate stream to said rich stream to preheat said rich stream, and a second junction at which said intermediate stream and said preheated rich stream are combined.

27. The apparatus of claim 26 wherein said regenerating system further includes a second heat exchanger, and wherein said intermediate stream is condensed in said first and second heat exchangers, and wherein said regenerating subsystem further includes a pump that increases the pressure of said intermediate stream after it has been condensed, and wherein said pumped intermediate stream passes through said second heat exchanger to be preheated prior to travel to said second junction.

28. The apparatus of claim 27 wherein said first lean stream passes through said second heat exchanger to be preheated using heat from said cooling of said intermediate stream prior to travel to said first junction.

29. The apparatus of claim 23 wherein said distillation/condensation subsystem generates a second lean stream and includes a first junction for combining said second lean stream with said spent stream to provide a combined stream, and a condenser that condenses said combined stream by transferring heat to a low temperature fluid source.

30. The apparatus of claim 29 wherein said distillation/condensation subsystem further comprises a stream separator that separates at least part of said combined stream in said distillation/condensation subsystem into an original lean stream used to provide said first and second lean streams and an original enriched stream used to provide said rich stream.

31. The apparatus of claim 30 wherein said distillation/condensation subsystem further comprises a stream splitter that splits said original lean stream to provide said first and second lean streams.

32. The apparatus of claim 30 wherein said original enriched stream is in the form of a vapor, said original lean stream is in the form of a liquid.

33. The apparatus of claim 32 wherein said distillation/condensation subsystem includes heat exchangers in which said original enriched stream and lean streams are cooled by transferring heat to preheat and partially vaporize said at least part of said combined stream prior to separating in said separator.

34. The apparatus of claim 30 wherein said distillation/condensation subsystem further comprises a splitter that splits said combined stream into a first combined stream portion that is directed to said stream separator and a second combined stream portion, and further comprises a junction at which said second combined stream portion and said original enriched stream are combined to provide said rich stream.

35. The apparatus of claim 34 wherein said distillation/condensation subsystem further comprises a second condenser at which said rich stream is condensed by transferring heat to said low temperature fluid source and further includes a pump that pumps said condensed rich stream to increase its pressure.

36. The apparatus of claim 34 wherein said distillation/condensation subsystem includes a heat exchanger in which said original enriched stream is cooled by transferring heat to preheat said rich stream.

37. The apparatus of claim 36 wherein said distillation/condensation subsystem includes a heat exchanger to cool said second lean stream prior to combining with said spent stream at said first junction by transferring heat to said first combined stream portion.

38. The apparatus of claim 36 wherein said distillation/condensation subsystem includes a heat exchanger to cool said spent stream prior to said combining with said second lean stream at said first junction by transferring heat to said first combined stream portion.