HELIUM MANAGEMENT CONTROL SYSTEM

• US 20100313583A1
• Filed: 08/02/2010
• Published: 12/16/2010
• 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: Andeen, Bruce, Dresens, Paul E., Than, Y. Roberto, Ash, Gary S., Chopy, Joseph JR., Bartlett, Allen J.
• Granted Patent: US 8,261,562 B2
• Time in Patent Office: Days
• US Class Current: 62/117
• 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 the supply of refrigerant to a plurality of refrigerators comprising:

a compressor bank including at least one compressor, the compressor including a high pressure supply line and a low pressure exhaust line, the compressor bank capable of supplying a refrigerant;

one or more sensors attached to the high pressure supply line and low pressure exhaust line to determine a differential pressure between the high pressure supply line and the low pressure exhaust line;

a plurality of refrigerators coupled to the compressor bank, the refrigerators adapted to consume the refrigerant; and

an electronic controller capable of determining a mode of control in accordance with the differential pressure.

2. The system of claim 1 wherein the mode of control comprises normal, over pressure and under pressure control modes.

3. The system of claim 1 wherein the refrigerators are capable of altering refrigerant consumption in response to the differential pressure reaching a differential pressure set point.

4. The system of claim 2 wherein the compressor bank is capable of reducing the total supply of refrigerant to the refrigerators in response to the over pressure control mode.

5. The system of claim 2 wherein the compressor bank is capable of increasing the total supply of refrigerant to the refrigerators in response to the under pressure control mode.

6. The system of claim 2 wherein the compressor bank is capable of maintaining substantially constant total supply of refrigerant to the refrigerators in response to the normal pressure control mode.

7. A method for controlling the supply of refrigerant to a plurality of refrigerators including:

a compressor bank including at least one compressor, the compressor including a high pressure supply line and a low pressure exhaust line, the compressor bank capable of supplying a refrigerant;

one or more sensors attached to the high pressure supply line and low pressure exhaust line to determine a pressure differential between the high pressure supply line and the low pressure exhaust line;

a plurality of refrigerators coupled to the compressor bank, the refrigerators adapted to consume the refrigerant;

the refrigerant comprises helium;

an electronic controller coupled to the one or more pressure sensors, the method comprising;

determining a pressure differential based on the output of the one or more sensors associated with the high pressure supply line and the low pressure exhaust line;

determining an over pressure mode of control in accordance with the differential pressure, wherein the over pressure mode of control is indicative of excess supply of the refrigerant from the compressor bank;

reducing the excess supply of the refrigerant from the compressor bank.

8. The method of claim 7 wherein reducing the excess supply of the refrigerant from the compressor bank further comprises decreasing the speed of the at least one compressor.

9. The method of claim 7 wherein determining an over pressure mode of control further comprises comparing a differential pressure set point with the determined differential pressure.

10. The method of claim 9 wherein the differential pressure set point is tuned to provide alternative differential setpoints for the corresponding mode of control.

11. A method for controlling the supply of refrigerant to a plurality of refrigerators including:

a compressor bank including at least one compressor, the compressor including a high pressure supply line and a low pressure exhaust line, the compressor bank capable of supplying a refrigerant;

the refrigerant comprises helium;

one or more sensors attached to the high pressure supply line and low pressure exhaust line to determine a pressure differential between the high pressure supply line and the low pressure exhaust line;

a plurality of refrigerators coupled to the compressor bank, the refrigerators adapted to consume the refrigerant;

an electronic controller coupled to the one or more pressure sensors, the method comprising;

determining a differential pressure in accordance with reading the output signals from the one or more sensors;

determining a mode of control in accordance with the differential pressure, wherein the mode of control comprises normal, over pressure and under pressure control modes;

varying the supply of the refrigerant from the compressor bank in accordance with the determined mode of control;

wherein the supply of refrigerant from the compressor bank is increased as a result of increasing the speed of the at least one compressor while the determined mode of control is under pressure and the supply of refrigerant from the compressor bank is decreased as a result of reducing the speed of the at least one compressor while the determined mode of control is over pressure.