Molten salt receiver cooling system

• US 6,701,711 B1
• Filed: 11/11/2002
• Issued: 03/09/2004
• Est. Priority Date: 11/11/2002
• Status: Expired due to Term

• Current Assignee: SolarReserve Technology, LLC
• Original Assignee: The Boeing Co.
• Inventors: Litwin, Robert Z.
• Primary Examiner(s): NGUYEN, HOANG M
• Application Number:
  US10/291,927
• Time in Patent Office: 484 Days
• Field of Search: 606/418, 606/411.1, 606/411.5
• US Class Current: 60/641.11
• CPC Class Codes: F02C 1/05 characterised by the type or source of heat, e.g. using nuclear or solar energy
• CPC Class Codes: F03G 6/06 with solar energy concentrating means
• CPC Class Codes: F03G 6/063 Tower concentrators
• CPC Class Codes: F03G 6/067 Binary cycle plants where the fluid from the solar collector heats the working fluid via a heat exchanger
• CPC Class Codes: F24S 20/20 Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
• CPC Class Codes: F24S 40/50 Preventing overheating or overpressure by draining the working fluid F24S40/60
• CPC Class Codes: F24S 80/20 Working fluids specially adapted for solar heat collectors
• CPC Class Codes: F28D 2020/0047 using molten salts or liquid metals
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines

Abstract

A flow of molten salt is provided through a solar-thermal heat exchange receiver. The receiver converts solar energy, reflected from heliostats, to thermal energy that is stored in molten salt. A vessel holds a store of molten salt for cooling the receiver upon a loss of flow. At the outlet of the receiver, an air separator removes air entrained in the flow of molten salt. From the air separator, the flow of molten salt proceeds through a downcomer having flow obstacles to a hot storage tank.

Claims

1. A system for cooling a receiver heat exchanger of a molten salt receiver system, comprising:

a molten salt holding vessel;

a receiver heat exchanger having an inlet downstream of the holding vessel and an outlet, the inlet and outlet permitting flow of molten salt through the heat exchanger;

an air separator having an inlet downstream of the receiver heat exchanger and an outlet, the air separator permitting the release of air entrained in the molten salt flow from the receiver heat exchanger;

a downcomer downstream of the air separator outlet and capable of delivering molten salt to a molten salt energy generation system; and

at least one flow obstacle within the downcomer.

2. The system according to claim 1, wherein the at least one flow obstacle comprises a passive flow restrictor.

3. The system according to claim 2, wherein the passive flow restrictor is selected from the group consisting of an orifice, a baffle, and open cell metal foam.

4. The system according to claim 1, wherein the flow obstacle is a turbine.

5. The system according to claim 4, wherein the turbine comprises a turbine generator.

6. The system according to claim 1, further comprising at least one isolation valve connecting the holding vessel and the receiver heat exchanger, the isolation valve capable of automatically opening upon a predetermined flow condition.

7. The system according to claim 6, further comprising a hot molten salt storage tank downstream of the downcomer and capable of delivering molten salt to a molten salt energy generation system.

8. The system according to claim 7, further comprising a vent system connecting the air separator and the hot molten salt storage tank.

9. The system according to claim 6, further comprising a pressurization system connected to the holding vessel and adapted to permit selective pressurization of the holding vessel.

10. The system according to claim 9, wherein the pressurization system further comprises an overpressure relief.

11. The system according to claim 6, further comprising a controller for automatically opening the isolation valve upon the flow through the receiver heat exchanger falling below a predefined threshold.

12. The system according to claim 11, further comprising a flow sensor interconnected to the controller and adapted to sense flow through the receiver heat exchanger, wherein the controller automatically opens the isolation valve in response to a signal from the flow sensor.

13. The system according to claim 6, wherein the holding vessel has a capacity that permits filling the vessel with a volume of molten salt corresponding to a volume required to cool the receiver heat exchanger for at least one minute upon opening of the isolation valve.

14. The system according to claim 6, further comprising:

a molten salt source;

a pump adapted to receive molten salt from the molten salt source and to urge flow through the receiver heat exchanger, the outlet of the pump being interconnected to the outlet of the holding vessel;

a check valve for preventing reverse flow through the pump; and

a flow control valve downstream of the pump.

15. The system according to claim 14, wherein the molten salt source comprises a cold molten salt storage tank.

16. The system according to claim 14, wherein the isolation valve automatically opens upon the predetermined flow condition corresponding to a loss of power to the pump.

17. A molten salt receiver system, comprising:

a molten salt source;

a pump adapted to receive molten salt from the molten salt source and to urge flow of the molten salt;

a receiver heat exchanger having an inlet downstream of the pump and an outlet, the inlet and outlet permitting flow of molten salt through the heat exchanger;

a flow control valve downstream of the pump;

a molten salt holding vessel having an outlet interconnected downstream of the pump and upstream of the heat exchanger;

an air separator having an inlet downstream of the heat exchanger and an outlet, the air separator permitting the release of air entrained in the molten salt flow from the receiver heat exchanger;

a downcomer downstream of the air separator outlet for receiving molten salt flow therefrom;

at least one flow obstacle within the downcomer; and

a hot molten salt storage tank downstream of the air separator outlet for receiving molten salt flow from the downcomer.

18. The system according to claim 17, further comprising at least one isolation valve positioned to isolate the holding vessel outlet from the flow of molten salt between the pump and the receiver heat exchanger, the isolation valve also being capable of automatically opening upon a predetermined flow condition.

19. The system according to claim 18, further comprising a check valve positioned between the pump and the receiver heat exchanger for preventing reverse flow through the pump.

20. The system according to claim 17, wherein the at least one flow obstacle comprises a passive flow restrictor.

21. The system according to claim 20, wherein the passive flow restrictor is selected from the group consisting of an orifice, a baffle, and open cell metal foam.

22. The system according to claim 17, wherein the flow obstacle is a turbine.

23. The system according to claim 22, wherein the turbine comprises a turbine generator.

24. The system according to claim 17, further comprising a vent system connecting the air separator and the hot molten salt storage tank.

25. The system according to claim 17, further comprising a pressurization system connected to the holding vessel and adapted to permit selective pressurization of the holding vessel.

26. The system according to claim 25, wherein the pressurization system further comprises an overpressure relief.

27. The system according to claim 17, further comprising a controller for automatically opening the isolation valve upon the predetermined flow condition corresponding to a loss of power to the pump.

28. The system according to claim 17, further comprising a controller for automatically opening the isolation valve upon the flow through the receiver heat exchanger falling below a predefined threshold.

29. The system according to claim 28, further comprising a flow sensor adapted to sense flow through the receiver heat exchanger, wherein the isolation valve automatically opens in response to a signal from the flow sensor.

30. The system according to claim 17, wherein the holding vessel has a capacity that permits filling the holding vessel with a volume of molten salt corresponding a volume required to cool the receiver heat exchanger for at least one minute upon opening of the isolation valve.

31. The system according to claim 17, wherein the molten salt source comprises a cold storage tank.

32. A method for cooling a receiver heat exchanger of a molten salt receiver system comprising:

permitting flow of molten salt through the receiver heat exchanger;

releasing air entrained in the flow of molten salt after the molten salt has passed through the receiver heat exchanger;

delivering the molten salt to a molten salt energy generation system after releasing the entrained air therefrom;

monitoring the flow of molten salt to detect an occurrence of a predetermined flow condition; and

automatically supplementing the flow of molten salt to the receiver heat exchanger with molten salt from a molten salt holding vessel upon the detection of the occurrence of the predetermined flow condition.

33. The method according to claim 32, wherein the step of automatically supplementing flow is initiated by automatically opening a valve isolating the molten salt holding vessel.

34. The method according to claim 33, wherein the step of monitoring includes monitoring flow through the receiver heat exchanger to detect the predetermined flow condition corresponding to flow falling below a predefined threshold.

35. The method according to claim 33, wherein the step of monitoring includes monitoring an electric pump power supply to detect the predetermined flow condition corresponding to loss of power to the electric pump.

36. The method according to claim 32, wherein the step of automatically supplementing flow lasts at least one minute.

37. The method according to claim 36, further comprising filling the molten salt holding vessel to a level corresponding to a volume required during the step of automatically supplementing flow.

38. The method according to claim 32, wherein the step of delivering molten salt includes passively restricting flow of molten salt.