Helium management control system

• US 20070107448A1
• Filed: 10/31/2006
• Published: 05/17/2007
• Est. Priority Date: 07/20/2001
• Status: Active Grant

• Current Assignee: Edwards Vacuum, LLC (Atlas Copco AB)
• Original Assignee: Brooks Automation Incorporated (Azenta, Inc.)
• Inventors: Ash, Gary, Dresens, Paul, Andeen, Bruce, Chopy, Joseph, Than, Y., Bartlett, Allen
• Granted Patent: US 7,788,942 B2
• Time in Patent Office: Days
• US Class Current: 62/149
• CPC Class Codes: B01D 8/00 Cold traps; Cold baffles pumps for evacuating by condensing or freezing F04B37/08
• CPC Class Codes: F04B 37/08 by condensing or freezing, e.g. cryogenic pumps
• CPC Class Codes: F17D 1/04 for distribution of gas
• CPC Class Codes: F17D 3/01 for controlling, signalling, or supervising the conveyance of a product
• CPC Class Codes: F17D 3/18 for measuring the quantity of conveyed product measuring volume or volume flow, in general G01F
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 2110/50 Air quality properties
• CPC Class Codes: F25B 2309/001 with a linear configuration or a linear motor
• CPC Class Codes: F25B 2309/002 with parallel working cold producing expansion devices in one circuit
• CPC Class Codes: F25B 2309/1428 Control of a Stirling refrigeration machine
• CPC Class Codes: F25B 2345/001 Charging refrigerant to a cycle
• CPC Class Codes: F25B 2345/003 Control issues for charging or collecting refrigerant to or from a cycle
• CPC Class Codes: F25B 45/00 Arrangements for charging or discharging refrigerant
• CPC Class Codes: F25B 9/002 characterised by the refrigerant
• CPC Class Codes: F25B 9/14 characterised by the cycle used, e.g. Stirling cycle
• CPC Class Codes: F25J 1/0007 Helium

Abstract

A helium management control system for controlling the helium refrigerant supply from a common manifold supplies a plurality of cryogenic refrigerators with an appropriate helium supply. The system employs a plurality of sensors to monitor and regulate the overall refrigerant supply to deliver an appropriate refrigerant supply to each of the cryogenic refrigerators depending on the computed aggregate cooling demand of all of the cryogenic refrigerators. An appropriate supply of helium is distributed to each cryopump by sensing excess and sparse helium refrigerant and redistributing refrigerant accordingly. If the total refrigeration supply exceeds the total refrigerant demand, or consumption, excess refrigerant is directed to cryogenic refrigerators which can utilize the excess helium to complete a current cooling function more quickly. Similarly, if the total refrigeration demand exceeds the total refrigeration supply, the refrigerant supply to some or all of the cryogenic refrigerators will be reduced accordingly so that detrimental or slowing effects are minimized based upon the current cooling function.

Claims

1. A system for controlling distribution of a refrigerant among a plurality of refrigerators comprising:

a plurality of refrigerators adapted to consume a refrigerant;

a controller operable to;

(i) compute an available quantity of the refrigerant, (ii) determine a demand from each of the refrigerators, the demand depending on the current operation of the refrigerator, (iii) compute an allocation of the refrigerant to each of the refrigerators based on an aggregated demand, the available quantity of the refrigerant, and the individual refrigerant demands of the refrigerators, and (iv) control the consumption of a refrigerant by a refrigerator.

2. The system of claim 1 wherein the controller is operable to recompute the available quantity of the refrigerant and further operable to recompute the allocation of the refrigerant based on the recomputed available quantity of the refrigerant.

3. The system of claim 2 further comprising a controller state indicative of demand for and availability of the refrigerant, wherein computing and recomputing the allocation of the refrigerant includes computing based on the controller state.

4. The system of claim 3 wherein a monitor state is indicative of a sufficient allocation of the refrigerant to all of the refrigerators.

5. The system of claim 3 wherein a distribution per demand state is indicative of at least one refrigerant having an insufficient allocation of the refrigerant.

6. The system of claim 3 wherein an overload state is indicative of at least one of the refrigerators having an insufficient allocation of the refrigerant.

7. The system of claim 3 wherein a distribution per hierarchy state is indicative of selectively diverting the refrigerant away from refrigerators according to a predetermined order.

8. The system of claim 3 wherein the controller is further operable to compute the controller state based on a setpoint, the setpoint corresponding to equilibrium between the quantity of the refrigerant and the aggregate demand.

9. The system of claim 2 further comprising a refrigerator status and mode indicative of refrigerant demand of the refrigerant, wherein computing and recomputing the allocation of the refrigerant includes computing based on the refrigerator status and mode.

10. The system of claim 2 wherein computing and recomputing occurs according to a predetermined set of rules and thresholds.

11. The system of claim 2 wherein the controller is further operable to compute and recompute the allocation based on at least one operating parameter of the refrigerator.

12. The system of claim 11 wherein the at least on operating parameter is a differential pressure (DP).

13. The system of claim 1 wherein the controllers are further operable to compute the demand of the refrigerant by the refrigerant based on at least one operating parameter of the refrigerator.

14. The system of claim 13 wherein the operating parameters include parameters selected from the group consisting of temperature, supply pressure, return pressure, speed, and allocated helium.

15. The system of claim 1 wherein the demand is indicative of a rate of helium consumption over time.

16. The system of claim 1 wherein the refrigerators have variable rates of consumption.

17. The system of claim 1 wherein the allocation further comprises a maximum consumption rate.

18. The system of claim 1 wherein the controller is further operable to regulate the displacer drive motor of each of the refrigerators to control consumption of the refrigerant.

19. The system of claim 1 wherein the controller is further operable to reduce the total refrigerant supply if there is no demand for excess refrigerant.

20. The system of claim 1 wherein the refrigerators are included in cryopumps.

21. The system of claim 20 wherein the cryopump has at least one stage.

22. The system of claim 20 wherein the cryopump has a plurality of stages.

23. The system of claim 20 wherein each of the cryopumps has a first stage and a second stage, and computing the demand further comprises reading the temperature of the first stage and the second stage and computing in response to the temperature.

24. The system of claim 1 wherein the refrigerator is included in a waterpump.

25. The system of claim 1 wherein the system is a fluid supply system.

26. The system of claim 1 wherein the refrigerant is helium.

27. The system of claim 1 wherein the refrigerant is distributed from a common manifold.

28. The system of claim 1 wherein the controller is a cryopump system controller.

29. A system for controlling distribution of a refrigerant among a plurality of refrigerators comprising:

a plurality of refrigerators adapted to consume a refrigerant;

a plurality of slave controllers each controlling consumption of a refrigerant by a refrigerator, the slave controller operable to compute a demand of the refrigerant by the refrigerator depending on the current operation of the refrigerator;

a master controller in communication with each of the slave controllers, the master controller operable to compute an available quantity of the refrigerant, and further operable to receive a demand from each of the refrigerators and compute an allocation of the refrigerant to each of the refrigerators based on an aggregated demand, the available quantity of the refrigerant, and the individual refrigerant demands of the refrigerators.

30. The system of claim 29 wherein the master controller is operable to recompute the available quantity of the refrigerant and further operable to recompute the allocation of the refrigerant based on the recomputed available quantity of the refrigerant.

31. The system of claim 30 further comprising a master controller state indicative of demand for and availability of the refrigerant, wherein computing and recomputing the allocation of the refrigerant includes computing based on the master controller state.

32. The system of claim 30 wherein computing and recomputing in the master and slave controllers occurs according to a predetermined set of rules and thresholds.

33. The system of claim 30 wherein the master controller is further operable to compute and recompute the allocation based on at least one operating parameter of the refrigerator.

34. The system of claim 33 wherein the at least on operating parameter is a differential pressure (DP).

35. The system of claim 29 wherein the slave controllers are further operable to compute the demand of the refrigerant by the refrigerant based on at least one operating parameter of the refrigerator.

36. The system of claim 35 wherein the operating parameters include parameters selected from the group consisting of temperature, supply pressure, return pressure, speed, and allocated helium.

37. The system of claim 29 wherein the slave controller is further operable to regulate the displacer drive motor of each of the refrigerators to control consumption of the refrigerant.

38. The system of claim 29 wherein the master controller is further operable to reduce the total refrigerant supply if there is no demand for excess refrigerant.

39. A computer-readable medium having stored thereon sequences of instructions, the sequences of instructions including instructions, when executed by a processor, causes the processor to perform:

determining an available quantity of the refrigerant;

determining a demand of the refrigerant by each of the plurality of refrigerators, the demand depending on the operation of each refrigerator;

aggregating the refrigerant demand of the refrigerators;

determining, for each of the refrigerators, an allocation of the refrigerant based on the availability of the refrigerant, the aggregated refrigerant demand and the individual refrigerant demands of the refrigerators with respect to the other refrigerators, the allocation computed as a portion of the determined available quantity;

distributing the refrigerant to the refrigerators based on the determined allocation; and

redistributing the allocation of the refrigerant over time by redetermining the allocation of the refrigerant.

40. A computer data signal including program code for controlling distribution of refrigerant among a plurality of refrigerators comprising:

program code for determining an available quantity of the refrigerant;

program code for determining a demand of the refrigerant by each of the plurality of refrigerators, the demand depending on the operation of each refrigerator;

program code for aggregating the demand from the refrigerators;

program code for determining, for each of the refrigerators, an allocation of the refrigerant based on the availability of the refrigerant, the aggregated refrigerant demand and the individual refrigerant demands of the refrigerators with respect to the other refrigerators, the allocation computed as a portion of the determined available quantity;

program code for distributing the refrigerant to the refrigerators based on the determined allocation; and

program code for redistributing the allocation of the refrigerant over time by redetermining the allocation of the refrigerant.

41. A system for controlling distribution of a refrigerant among a plurality of refrigerators comprising:

means for determining an available quantity of the refrigerant;

means for determining a demand of the refrigerant by each of the plurality of refrigerators, the demand depending on the operation of each refrigerator;

means for aggregating the demand from the refrigerators;

means for determining, for each of the refrigerators, an allocation of the refrigerant based on the availability of the refrigerant, the aggregated refrigerant demand and the individual refrigerant demands of the refrigerators with respect to the other refrigerators, the allocation computed as a portion of the determined available quantity;

means for distributing the refrigerant to the refrigerators based on the determined allocation; and

means for redistributing the allocation of the refrigerant over time by redetermining the allocation of the refrigerant.

42. A helium management control system for a plurality of cryogenic refrigerators comprising:

a plurality of cryogenic refrigerators connected to a common refrigerant source, each of the cryogenic refrigerators operable to cool a refrigerant load;

a drive motor connected to each of the cryogenic refrigerators and operable to regulate the helium consumed by the cryogenic refrigerators;

at least one sensor in communication with each of the cryogenic refrigerators adapted to sense at least one operating parameter indicative of the operating state of the cryogenic refrigerators;

a controller operable to receive the operating parameters and compute an aggregate refrigerant load indicative of a plurality of the refrigerant loads, the controller further operable to compute an allocation signal as a result of the aggregate refrigerant load; and

a drive motor controller connected to each of the sensors and to each of the drive motors, the controller operable to regulate the drive motor in response to the allocation signals.

43. The system of claim 42 further including a refrigerant capacity indicative of a cooling potential of the common refrigerant source, the controller further operable to compute the allocation signal as a result of the refrigerant capacity.

44. The system of claim 43 wherein the refrigerant capacity is a computed available helium supply driven by a compressor.

45. The system of claim 42 wherein the cryogenic refrigerator is in a cryogenic pump.

46. The system of claim 42 wherein the controller is further operable to compute the allocation signal based on the temperature of the refrigerant, the computed flow rate of the refrigerant, the pressure of the refrigerant, and the speed of the motor.

47. The system of claim 46 further including a control loop in the controller operable to compute the allocation signal as a result of the parameters.

48. The system of claim 47 wherein the control loop is a closed feedback loop.

49. The system of claim 42 wherein each of the cryogenic refrigerators is operable to perform a plurality of cryogenic functions and the drive signal is computed based on the cryogenic function.

50. The system of claim 42 wherein the controller is operable to recompute the consumption signal at regular, predetermined intervals.

51. The system of claim 42 wherein the at least one sensor includes a temperature sensor.

52. The system of claim 42 wherein the at least one sensor includes a pressure sensor.