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US 4,809,154 AGranted
Automated control system for a multicomponent refrigeration system
AssigneeAir Products and Chemicals, Inc.
InventorCharles L. Newton
Life of this patent
Estimating the term…
Abstract
An automated control system for the control of mixed refrigerant-type liquified natural gas production facilities comprising optimization of functional parameters, concurrent monitoring and adjustment of critical operational limits, and maximization of production functions. Optimization is accomplished by adjusting parameters including mixed refrigerant inventory, composition, compression ratio, and compressor turbine speeds to achieve the highest product output value for each unit of energy consumed by the facility.
Claims18
A method for efficiently operating a liquefied natural gas production facility comprising the steps of:
- monitoring key variables representative of the state of operation of said facility;
- determining a desired production rate for said facility;
- comparing said desired production rate to the value of a key variable representative of the current production rate of said facility;
- setting a plurality of controllers to change production to a rate equal to said desired rate;
- and
- controlling and optimizing mixed refrigerant composition and mixed refrigerant compression ratio as well as other plant operating variables with respect to overall efficiency by means of adjusting an operating parameter selected from the group consisting of:
- (a) mixed refrigerant make up rate;
- (b) mixed refrigerant venting;
- (c) mixed refrigerant liquid draining;
- (d) compressor turbine speed;
- (e) relative mixed refrigerant liquid and vapor flows;
- and
- (f) fuel header pressure.
10 more elements
A method for efficiently operating a liquefied natural gas production facility comprising the steps of:
- monitoring key variables representative of the state of operation of said facility;
- monitoring compressors for surge condition and opening a recycle valve to prevent surge;
- determining a desired production rate for said facility;
- comparing said desired production rate to the value of a key variable representative of the current production rate of said facility;
- setting a plurality of controllers to increase or to decrease production to a rate equal to said desired rate;
- and
- optimizing operation by maintaining mixed refrigerant liquid inventory within a predetermined range, adjusting mixed refrigerant composition and mixed refrigerant compression ratio with respect to overall efficiency.
4 more elements
A method for efficiently operating a liquefied natural gas production facility comprising the steps of:
- (a) determining a desired production rate;
- (b) determining the current production rate;
- (c) determining the cold-end temperature differential ( I.sub.CE) ;
- (d) comparing said desired production rate to said current production rate;
- and
- (e) increasing production if said current production rate is below said desired production rate by:
- (i) if T.sub.CE <a predetermined minimum then:
- injecting a predetermined amount of nitrogen into the mixed refrigerant inventory of said facility:
- (ii) if T.sub.CE >said predetermined minimum then:
- injecting methane into the mixed refrigerant inventory of said facility until the mixed refrigerant compressor suction pressure rises by a predetermined amount;
- (iii) optimizing mixed refrigerant liquid inventory, mixed refrigerant composition with respect to overall efficiency;
- or
- (f) decreasing production if said current production rate is above said desired production rate by:
- (i) decreasing mixing refrigerant compressor suction pressure;
- (ii) optimizing mixed refrigerant liquid inventory, mixed refrigerant compression ratio, and mixed refrigerant composition with respect to overall efficiency;
- or
- (g) optimizing overall facility efficiency if said current production rate is equal to said desired production rate by maintaining mixed refrigerant liquid inventory within a predetermined range.
14 more elements
A method for efficiently operating a liquefied natural gas production facility comprising the steps of:
- (a) determining a desired production rate;
- (b) determining the current production rate;
- (c) comparing said desired production rate
- to said current production rate;
- (d) increasing production if aid current production rate is below said desired
- production rate by;
- (i) if T.sub.CE <a predetermined minimum then:
- injecting a predetermined amount of nitrogen into the mixed refrigerant inventory of said facility;
- (ii) if T.sub.CE >said predetermined minimum then:
- injecting methane into the mixed refrigerant inventory of said facility until the mixed refrigerant compressor suction pressure rises by a predetermined amount;
- (iii) optimizing mixed refrigerant liquid Inventory, mixed refrigerant compression ratio, and mixed refrigerant composition with respect to overall efficiency;
- and
- decreasing production if said current production rate is above said desired production rate by:
- (i) decreasing mixed refrigerant compressor suction pressure;
- (ii) optimizing mixed refrigerant liquid inventory, mixed refrigerant compression ratio, and mixed refrigerant composition with respect to overall efficiency;
- and
- optimizing overall facility efficiency if said current production rate is equal to said desired production rate by (ii) adjusting mixed refrigerant composition with reference to overall facility efficiency.
14 more elements
A method for efficiently operating a liquefied natural gas production facility comprising the steps of:
- (a) determining a desired production rate;
- (b) determining the current production rate;
- (c) comparing said desired prodution rate to said current production rate;
- (d) increasing production if said current production rate is below said desired production rate by:
- (i) if T.sub.CE <a predetermined minimum then:
- injecting a predetermined amount of nitrogen into the mixed refrigerant inventory of said facility;
- (ii) if T.sub.CE >said predetermined minimum then:
- injecting methane into the mixed refrigerant inventory of said facility until the mixed refrigerant compressor suction pressure rises by a predetermined amount;
- (iii) optimizing mixed refrigerant liquid inventory mixed refrigerant compression ratio, and mixed refrigerant composition with respect to overall efficiency;
- and
- decreasing production if said current production rate is above said desired production rate by:
- (i) decreasing mixed refrigerant compressor suction pressure;
- (ii) optimizing mixed refrigerant liquid inventory, mixed refrigerant compression ratio, and mixed refrigerant composition with respect to overall efficiency;
- and
- optimizing overall facility efficiency if said current production rate is equal to said desired production rate by (iii) adjusting refrigerant compression ratio with reference to overall facility efficiency.
12 more elements
A method for efficiently operating a liquefied natural gas production facility comprising the steps of:
- (a) determining a desired production rate;
- (b) determining the current production rate;
- (c) comparing said desired production rate to said current production rate;
- (d) increasing production if said current production rate is below said desired production rate by:
- (i) if T.sub.CE <a predetermined minimum then:
- injecting a predetermined amount of nitrogen into the mixed refrigerant inventory of said facility;
- (ii) if T.sub.CE >said predetermined minimum then:
- injecting methane into the mixed refrigerant inventory of said facility until the mixed refrigerant compressor suction pressure rises by a predetermined amount;
- (iii) optimizing mixed refrigerant liquid inventory, mixed refrigerant compression ratio, and mixed refrigerant composition with respect to overall efficiency;
- and
- decreasing production if said current production rate is above said desired production rate by:
- (i) decreasing mixed refrigerant compressor suction pressure;
- (ii) optimizing mixed refrigerant liquid inventory, mixed refrigerant compression ratio, and mixed refrigerant composition with respect to overall efficiency;
- and
- optimizing overall facility efficiency if said current production rate is equal to said desired production rate by (iv) adjusting compressor turbine speeds with reference to overall facility efficiency.
12 more elements
A method for maximizing the output of a liquefied natural gas production facility comprising the steps of:
- (a) setting the desired production rate to a predetermined value, said value being higher than the maximum attainable production rate of said facility;
- (b) determining the current production rate;
- (c) if said current production rate is below the maximum attainable production rate, then increasing production to said maximum attainable level by repeatedly performing the steps of:
- (i) determining the cold-end temperature differential (.DELTA.T.sub.CE);
- (ii) comparing said determined .DELTA.T.sub.CE to a predetermined minimum value;
- (iii) if said .DELTA.T.sub.CE is less than said minimum value, then injecting a predetermined amount of nitrogen into mixed refrigerant inventory of said facility, waiting a predetermined period of time;
- (iv) if said .DELTA.T.sub.CE is greater than or equal to said minimum value, then:
- injecting methane into the mixed refrigerant inventory of said facility, until an operational parameter design limit is exceeded, or until a predetermined mixed refrigerant compressor suction pressure is reached.
5 more elements
Dependencies are inferred from the claim text.