Closed Cryogen Cooling System And Method For Cooling A Superconducting Magnet

• US 20150128617A1
• Filed: 04/24/2013
• Published: 05/14/2015
• Est. Priority Date: 06/01/2012
• Status: Abandoned Application

• Current Assignee: Siemens Healthcare Limited. (Siemens AG)
• Original Assignee: Siemens PLC (Siemens AG)
• Inventors: Mikheev, Vladimir
• Application Number:
  US14/401,251
• Publication Number:
  US 20150128617A1
• Time in Patent Office: Days
• US Class Current: 62/47.1
• CPC Class Codes: F17C 13/021 having the height as the parameter
• CPC Class Codes: F17C 5/00 Methods or apparatus for filling containers with liquefied, solidified, or compressed gases under pressures adding propellants to aerosol containers B65B31/00
• CPC Class Codes: F25B 2400/17 Re-condensers
• CPC Class Codes: F25D 19/00 Arrangement or mounting of refrigeration units with respect to devices or objects to be refrigerated, e.g. infrared detectors
• CPC Class Codes: G01R 33/3804 Additional hardware for cooling or heating of the magnet assembly, for housing a cooled or heated part of the magnet assembly or for temperature control of the magnet assembly

Abstract

In a cryogen cooling system for cooling a superconducting magnet, a cryogen vessel is linked to a cooling loop arrangement in thermal contact with the superconducting magnet. A recondensing chamber is arranged such that a lower extremity of the cryogen vessel is above a lower extremity of the recondensing chamber. A recondensing refrigerator is arranged to recondense cryogen gas within the recondensing chamber. A heater is positioned to heat gaseous cryogen within the recondensing chamber, and wherein the recondensing chamber is hydraulically connected to the cryogen vessel by a cryogen supply pipe. An upper end of the cryogen supply pipe is exposed to cryogen gas in the cryogen vessel and a lower end of cryogen supply pipe is exposed to an interior of the recondensing chamber towards or at its lower extremity.

Claims

1-21. -21. (canceled)

22. A cryogen cooling system for cooling a superconducting magnet, comprising:

a cryogen vessel linked to a cooling loop arrangement in thermal contact with the superconducting magnet;

a recondensing chamber arranged such that a lower extremity of the cryogen vessel is above a lower extremity of the recondensing chamber;

a recondensing refrigerator arranged to recondense cryogen gas within the recondensing chamber; and

a heater positioned to heat gaseous cryogen within the recondensing chamber, and wherein the recondensing chamber is hydraulically connected to the cryogen vessel by a cryogen supply pipe, an upper end of the cryogen supply pipe being exposed to cryogen gas in the cryogen vessel and a lower end of the cryogen supply pipe being exposed to an interior of the recondensing chamber towards or at its lower extremity.

23. The cryogen cooling system according to claim 22 further comprising a sensor for detecting a minimum level of the liquid cryogen in the recondensing chamber.

24. The cryogen cooling system according to claim 22 further comprising a sensor for detecting a maximum level of the liquid cryogen in the recondensing chamber.

25. The cryogen cooling system according to claim 22 further comprising a sensor for detecting a maximum level of the liquid cryogen in the cryogen vessel.

26. The cryogen cooling system according to claim 22 further comprising a controller arranged to energize and de-energize the heater in response to signals provided by the sensor, or one of the sensors.

27. The cryogen cooling system according to claim 22 further comprising a valve provided to control flow through the cryogen supply pipe.

28. The cryogen cooling system according to claim 22 further comprising a removable plug for closing the lower end of the cryogen supply pipe.

29. The cryogen cooling system according to claim 22 wherein the heater is integrated into the recondensing refrigerator.

30. The cryogen cooling system according to claim 22 wherein the heater is attached to an outer surface of the recondensing chamber in thermal contact with the recondensing chamber.

31. The cryogen cooling system according to claim 22 wherein the upper end of the cryogen supply pipe is located at or near an upper extremity of the cryogen vessel.

32. The cryogen cooling system according to claim 31 wherein an umbrella is provided above the upper end of the cryogen supply pipe.

33. A cryogen cooling system for cooling a superconducting magnet, comprising:

a cryogen vessel linked to a cooling loop arrangement in thermal contact with the superconducting magnet;

a recondensing chamber arranged such that a lower extremity of the cryogen vessel is above a lower extremity of the recondensing chamber;

a recondensing refrigerator arranged to recondense cryogen gas within the recondensing chamber; and

a heater positioned to heat gaseous cryogen within the recondensing chamber, and wherein the recondensing chamber is hydraulically connected to the cryogen vessel by a first pipe which links an upper part of the recondensing chamber with an upper part of the cryogen vessel to provide a passage for flow of cryogen gas from the cryogen vessel to the recondensing chamber through a one-way valve, and a second pipe which links lower parts of the recondensing chamber and the cryogen vessel to provide a passage for flow of liquid cryogen in the recondensing chamber from the recondensing chamber to the cryogen vessel.

34. The cryogen cooling system according to claim 33 further comprising a sensor for detecting a minimum level of the liquid cryogen in the recondensing chamber.

35. The cryogen cooling system according to claim 33 further comprising a sensor for detecting a maximum level of the liquid cryogen in the recondensing chamber.

36. The cryogen cooling system according to claim 33 further comprising a sensor for detecting a maximum level of the liquid cryogen in the cryogen vessel.

37. The cryogen cooling system according to claim 34 further comprising a controller arranged to energize and de-energize the heater in response to signals provided by the sensor, or one of the sensors.

38. The cryogen cooling system according to claim 33 wherein the heater is integrated into the recondensing refrigerator.

39. The cryogen cooling system according to claim 33 wherein the heater is attached to an outer surface of the recondensing chamber in thermal contact with the recondensing chamber.

40. A method for replenishing a cryogen vessel of a cryogen cooling system for cooling a superconducting magnet with liquid cryogen, said cryogen cooling system comprising a cryogen vessel linked to a cooling loop arrangement in thermal contact with the superconducting magnet, a recondensing chamber arranged such that a lower extremity of the cryogen vessel is above a lower extremity of the recondensing chamber, a recondensing refrigerator arranged to recondense cryogen gas within the recondensing chamber, and a heater positioned to heat gaseous cryogen within the recondensing chamber, and wherein the recondensing chamber is hydraulically connected to the cryogen vessel by a cryogen supply pipe, an upper end of the cryogen supply pipe being exposed to cryogen gas in the cryogen vessel and a lower end of cryogen supply pipe being exposed to an interior of the recondensing chamber towards or at its lower extremity, comprising the steps of:

a) providing the cryogen in a closed volume comprising the recondensing chamber, the cryogen supply pipe, the cryogen vessel and the cooling loop arrangement;

b) operating the recondensing refrigerator to liquefy the cryogen gas within the recondensing chamber, thereby reducing a gas pressure within the recondensing chamber to below a gas pressure within the cryogen vessel;

c) supplying the cryogen gas from the cryogen vessel through the cryogen supply pipe to the recondensing chamber;

d) continuing to liquefy the cryogen gas within the recondensing chamber to provide a volume of the liquid cryogen within the recondensing chamber;

e) energizing the heater to heat the cryogen gas within the cryogen vessel to thereby increase a gas pressure within the recondensing chamber above a gas pressure within the cryogen vessel;

f) driving at least part of the volume of the liquid cryogen from the recondensing chamber through the cryogen supply pipe to the cryogen vessel by a difference in gas pressures in the recondensing chamber and the cryogen vessel; and

g) de-energizing the heater.

41. The method according to claim 40 further comprising cyclically repeating steps (b)-(g).

42. The method according to claim 41 wherein step (e) commences at predetermined time intervals corresponding to an expected accumulation of quantities of the liquid cryogen within the recondensing chamber.

43. The method according to claim 40 wherein step (e) commences in response to an output of a sensor indicating that a maximum level of the liquid cryogen is present in the recondensing chamber.

44. The method according to claim 40 wherein step (g) commences in response to an output of a sensor indicating that a minimum level of the liquid cryogen is present in the recondensing chamber.

45. The method according to claim 40 wherein step (e) commences in response to an output of a sensor indicating that a minimum level of the liquid cryogen is present in the cryogen vessel.

46. The method according to claim 40 wherein step (g) commences in response to an output of a sensor indicating that a maximum level of the liquid cryogen is present in the cryogen vessel.

47. The method according to claim 40 wherein steps (e) and (f) continue for fixed periods of time.

48. The method according to claim 40 wherein operation of the recondensing refrigerator is suspended during steps (e) and (f).