COMBINED GEOTHERMAL AND SOLAR THERMAL ORGANIC RANKINE CYCLE SYSTEM

• US 20110126539A1
• Filed: 05/02/2008
• Published: 06/02/2011
• Est. Priority Date: 05/02/2008
• Status: Active Grant

• Current Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Zhu, Guangyan, Ramaswamy, Sitaram
• Granted Patent: US 9,297,367 B2
• Time in Patent Office: Days
• US Class Current: 60/641.2
• CPC Class Codes: F01K 25/08 using special vapours
• CPC Class Codes: F03G 4/029 closed loop geothermal collectors, i.e. the fluid is pumped through a closed loop in heat exchange with the geothermal source, e.g. via a heat exchanger
• CPC Class Codes: F03G 4/035 of the Organic Rankine Cycle [ORC] type or the Kalina Cycle type
• CPC Class Codes: F03G 6/003 having a Rankine cycle F03G6/065 takes precedence
• CPC Class Codes: F03G 6/004 of the Organic Rankine Cycle [ORC] type or the Kalina Cycle type
• CPC Class Codes: F03G 7/04 using pressure differences or thermal differences occurring in nature F03G7/06 takes precedence
• CPC Class Codes: F05B 2270/303 Temperature
• CPC Class Codes: F05B 2270/506 hydraulic means, e.g. hydraulic valves within a hydraulic circuit
• CPC Class Codes: Y02E 10/10 Geothermal energy
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines

Abstract

In a system where the thermal energy of a geothermal fluid is applied to an ORC system, the energy is enhanced by the use of solar energy to thereby increase the temperature of the fluid being applied by the ORC system. A single heat exchanger version provides for direct heat exchange relationship with the geothermal and solar fluids, whereas a two heat exchanger version provides for each of the geothermal and solar fluids to be in heat exchange relationship with the working medium of the ORC system. Control features are provided to selectively balance the various fluid flows in the system.

Claims

1. An energy recovery system for use with a geothermal source containing a fluid which can be removed at a higher temperature and returned at a lower temperature, comprising:

an organic rankine cycle system having a closed loop circuit with a working fluid being circulated therethrough;

at least one heat exchanger fluidly connected to said organic rankine cycle system and said geothermal fluid for transferring heat from said geothermal fluid to said organic rankine cycle system; and

a plurality of solar collectors thermally coupled to said at least one heat exchanger for transferring heat from said solar collectors to said organic rankine cycle system.

2. An energy recovery system as set forth in claim 1 wherein said at least one heat exchanger comprises a single heat exchanger in which the heat from said plurality of solar collectors is transferred to the geothermal fluid with the geothermal fluid then passing to the organic rankine cycle system.

3. An energy recovery system as set forth in claim 1 wherein said at least one heat exchanger comprises two heat exchangers with one heat exchanger being so connected as to transfer heat from the geothermal fluid to the working fluid of the organic rankine cycle system and the other heat exchanger being so connected as to transfer heat from the plurality of solar collectors to the working fluid of the organic rankine cycle system.

4. An energy recovery system as set forth in claim 3 wherein the energy recovery system is configured for the working fluid to pass first through the one heat exchanger and then through the other heat exchanger.

5. An energy recovery system as set forth in claim 4 wherein the energy recovery system is configured for the working fluid to then pass to the turbine of the organic rankine cycle system.

6. An energy recovery system as set forth in claim 3 wherein the energy recovery system is configured for the working fluid to pass through the two heat exchangers in parallel.

7. An energy recovery system as set forth in claim 1 and including a pump for circulating the flow of geothermal fluid from the geothermal source to the organic rankine cycle system.

8. An energy recovery system as set forth in claim 1 wherein said fluid connecting said solar collectors to the other side of said heat exchangers is around 300°

C.

9. An energy recovery system as set forth in claim 1 and including a return flow conduit for conducting the flow of geothermal fluid back to said geothermal source.

10. An energy recovery system as set forth in claim 1 wherein the energy recovery system is configured for said geothermal fluid and said solar collector fluid to pass through said at least one heat exchanger in inverse flow relationship.

11. An energy recovery system as set forth in claim 3 wherein the energy recovery system is configured such that said geothermal fluid and said working fluid pass through said one heat exchanger in inverse parallel flow relationship.

12. An energy recovery system as set forth in claim 3 wherein the energy recovery system is configured such that said solar collector fluid and said working flow pass through said other heat exchanger in parallel inverse flow relationship.

13. An energy recovery system as set forth in claim 3 and including a pump for circulating said working fluid through said rankine cycle closed loop.

14. An energy recovery system as set forth in claim 13 wherein said pump is a variable speed pump and includes a control for selectively controlling the operating speed thereof.

15. An energy recovery system as set forth in claim 3 and including a second pump for pumping the geothermal fluid from said geothermal source.

16. An energy recovery system as set forth in claim 3 and including a valve that can be selectively controlled to modulate the flow from said geothermal source and a control for controlling said valve.

17. An energy recovery system as set forth in claim 16 and including a sensor for sensing the level of liquid in said one heat exchanger and further wherein said valve is controlled as a function of the difference between a sensed level of liquid in said one heat exchanger and a predetermined set point.

18. An energy recovery system as set forth in claim 16 and including a control for operating said valve as a function of the difference between a power feedback signal from said organic rankine cycle and a predetermined power set point.

19. An energy recovery system as set forth in claim 18 and including a pressure sensor and a temperature sensor for determining the pressure and temperature of the working fluid being discharged from said one heat exchanger and further wherein said valve is controlled as a function of those sensed pressure and temperature conditions.

20. An energy recovery system as set forth in claim 1 and including a control for determining whether solar heat is available from said solar collectors.

21. An energy recovery system as set forth in claim 20 and including a control feature for operating in the geothermal mode only if solar heat is not available.

22. An energy recovery system as set forth in claim 21 wherein, if said control determines that solar heat is available, determining whether the solar heat is sufficient, and if it is, operating in the solar mode alone and if it isn'"'"'t, operating in a combination of a solar and geothermal modes.

23. An energy recovery system as set forth in claim 21 wherein, if said control determines that solar is available, determining whether the temperature of the solar fluid exceeds the temperature of the geothermal fluid and if it is, operating in the solar mode only, and if it isn'"'"'t, operating in the geothermal mode only.

24. An energy recovery system for use with a geothermal source containing a thermal fluid, comprising:

an organic rankine cycle system having a closed loop circuit with a working fluid being circulated therethrough;

a first heat exchanger fluidly connected between said organic rankine cycle system and said geothermal fluid for transferring heat from said geothermal fluid to said organic rankine cycle working fluid;

a second heat exchanger having an augmenting fluid flowing therethrough and then to be mixed with said geothermal fluid, with the mixture passing through said first heat exchanger and with a portion of the mixture then passing back through said second heat exchanger; and

a plurality of solar collectors fluidly connected to said second heat exchanger for transferring heat from said solar collectors to said augmenting fluid.

25. An energy recovery system as set forth in claim 24 and including a pump for circulating said mixture portion through said second heat exchanger.

26. An energy recovery system for use with a geothermal source containing a geothermal fluid which can be removed at a higher temperature and returned at a lower temperature, comprising:

an organic rankine cycle system having a closed loop circuit with the geothermal fluid being circulated therethrough;

a heat exchanger fluidly connecting the downstream side of said organic rankine cycle system to said geothermal source; and

a plurality of solar collectors fluidly connected to said heat exchanger for transferring heat from said solar collectors to the fluid flowing to said geothermal source.

27. A geothermal energy recovery system as set for the in claim 26 and including a valve for selectively connecting or disconnecting said solar collectors to said heat exchanger.

28. A geothermal energy recovery system as set forth in claim 27 and including a control for sensing the temperature of the solar fluid and connecting the solar collectors to the heat exchanger only when that temperature exceeds the temperature of the working fluid leaving the organic rankine cycle