Compressor system and method for gas liquefaction system

Abstract

A system and method according to which a compressor having a first shaft is provided, and an aeroderivative gas turbine for driving the compressor is provided, the aeroderivative gas turbine including a gas generator and a power turbine coupled to the gas generator, the power turbine having a second shaft directly coupled to the first shaft of the compressor for directly driving the first shaft.

1 . A system for compressing a refrigerant, the system comprising:
 a compressor system comprising:
 a compressor through which the refrigerant is adapted to flow, the compressor comprising a first shaft; and 
 an aeroderivative gas turbine for driving the compressor, the aeroderivative gas turbine comprising:
 a gas generator; and 
 a low speed power turbine coupled to the gas generator, the low speed power turbine comprising a second shaft directly coupled to the first shaft of the compressor for directly driving the first shaft; 
 wherein the respective rotational speeds of the first and second shafts are substantially equal. 
 
   
     
     
         2 . The system of  claim 1 , further comprising:
 a gas liquefaction system for converting at least a portion of a fluid from a gas state into a liquid state, the fluid in the gas state comprising natural gas, the fluid in the liquid state comprising liquefied natural gas, the gas liquefaction system comprising:
 one or more cooling stages comprising:
 the refrigerant; and 
 a loop through which the refrigerant is adapted to circulate, the loop comprising:
 a heat exchanger for transferring heat out of the fluid and into the refrigerant; 
 the compressor of the compressor system for pressurizing the refrigerant; 
 a condenser for transferring heat out of the refrigerant; and 
 an expansion element for expanding the refrigerant; 
 
 
   wherein the aeroderivative gas turbine is coupled to the compressor as a modular unit;   wherein the low speed power turbine is coupled to the gas generator as a modular unit;   wherein the compressor comprises a centrifugal compressor;   wherein the refrigerant flows through the centrifugal compressor at a flow rate ranging from about 40,000 actual cubic feet per minute to about 70,000 actual cubic feet per minute;   wherein the compressor pressurizes the refrigerant so that the pressurized refrigerant is discharged from the compressor at a pressure ranging from about 30 pounds per square inch absolute to about 300 pounds per square inch absolute;   wherein the low speed power turbine comprises at least six expansion stages for driving the second shaft;   wherein the at least six expansion stages drives the second shaft so that the low speed power turbine has a power rating of less than about 55,000 horsepower;   wherein the first and second shafts are generally axially aligned; and   wherein the rotational speed of the first and second shafts ranges from about 2,000 revolutions per minute to about 4,000 revolutions per minute.   
     
     
         3 . The system of  claim 1 , wherein the first and second shafts are generally axially aligned; and
 wherein the rotational speed of the first and second shafts ranges from about 2,000 revolutions per minute to about 4,000 revolutions per minute.   
     
     
         4 . The system of  claim 1 , wherein the compressor comprises a centrifugal compressor configured so that the refrigerant is adapted to flow through the centrifugal compressor at a flow rate ranging from about 40,000 actual cubic feet per minute to about 70,000 actual cubic feet per minute; and
 wherein the centrifugal compressor is configured to pressurize the refrigerant so that the pressurized refrigerant is discharged from the centrifugal compressor at a pressure ranging from about 30 pounds per square inch absolute to about 300 pounds per square inch absolute.   
     
     
         5 . The system of  claim 1 , wherein the low speed power turbine comprises at least six expansion stages for driving the second shaft; and
 wherein the at least six expansion stages drives the second shaft so that the low speed power turbine has a power rating of less than about 55,000 horsepower.   
     
     
         6 . The system of  claim 1 , wherein the aeroderivative gas turbine is coupled to the compressor as a modular unit; and
 wherein the low speed power turbine is coupled to the gas generator as a modular unit.   
     
     
         7 . The system of  claim 1 , further comprising:
 a gas liquefaction system for converting at least a portion of a fluid from a gas state into a liquid state, the fluid in the gas state comprising natural gas, the fluid in the liquid state comprising liquefied natural gas, the gas liquefaction system comprising:
 one or more cooling stages comprising:
 the refrigerant; and 
 a loop through which the refrigerant is adapted to circulate, the loop comprising:
 a heat exchanger for transferring heat out of the fluid and into the refrigerant; 
 the compressor of the compressor system for pressurizing the refrigerant; 
 a condenser for transferring heat out of the refrigerant; and 
 an expansion element for expanding the refrigerant. 
 
 
   
     
     
         8 . A method of compressing a refrigerant, the method comprising:
 providing a compressor having a first shaft;   providing an aeroderivative gas turbine having a power turbine that includes a second shaft;   directly coupling the second shaft of the power turbine to the first shaft of the compressor;   circulating the refrigerant through the compressor; and   pressurizing the refrigerant with the compressor, comprising:
 directly driving the compressor using the aeroderivative gas turbine, comprising:
 rotating the first shaft of the power turbine at a first rotational speed; and 
 rotating the second shaft of the compressor at a second rotational speed; 
 wherein the first and second rotational speeds are substantially equal. 
 
   
     
     
         9 . The method of  claim 8 , further comprising:
 converting at least a portion of a fluid from a gas state into a liquid state, the fluid in the gas state comprising natural gas, the fluid in the liquid state comprising liquefied natural gas;   wherein converting at least a portion of the fluid from the gas state into the liquid state comprises transferring heat from the fluid and into the refrigerant;   wherein the compressor comprises a centrifugal compressor;   wherein the power turbine is a low speed power turbine comprising at least six expansion stages;   wherein circulating the refrigerant through the compressor comprises circulating the refrigerant through the compressor at a flow rate ranging from about 40,000 actual cubic feet per minute to about 70,000 actual cubic feet per minute;   wherein pressurizing the refrigerant with the compressor comprises pressurizing the refrigerant with the compressor so that the pressurized refrigerant is discharged from the compressor at a pressure ranging from about 30 pounds per square inch absolute to about 300 pounds per square inch absolute;   wherein rotating the first shaft of the power turbine at the first rotational speed comprises driving the first shaft using the at least six expansion stages so that the low speed power turbine has a power rating of less than about 55,000 horsepower;   wherein the first and second shafts are generally axially aligned; and   wherein each of the first and second rotational speeds ranges from about 2,000 revolutions per minute to about 4,000 revolutions per minute.   
     
     
         10 . The method of  claim 8 , further comprising:
 converting at least a portion of a fluid from a gas state into a liquid state, the fluid in the gas state comprising natural gas, the fluid in the liquid state comprising liquefied natural gas;   wherein converting at least a portion of the fluid from the gas state into the liquid state comprises transferring heat from the fluid and into the refrigerant.   
     
     
         11 . The method of  claim 8 , wherein the compressor comprises a centrifugal compressor;
 wherein circulating the refrigerant through the compressor comprises circulating the refrigerant through the compressor at a flow rate ranging from about 40,000 actual cubic feet per minute to about 70,000 actual cubic feet per minute; and   wherein pressurizing the refrigerant with the compressor comprises pressurizing the refrigerant with the compressor so that the pressurized refrigerant is discharged from the compressor at a pressure ranging from about 30 pounds per square inch absolute to about 300 pounds per square inch absolute.   
     
     
         12 . The method of  claim 8 , wherein the power turbine is a low speed power turbine comprising at least six expansion stages; and
 wherein rotating the first shaft of the power turbine at the first rotational speed comprises driving the first shaft using the at least six expansion stages so that the low speed power turbine has a power rating of less than about 55,000 horsepower.   
     
     
         13 . The method of  claim 8 , further comprising:
 decoupling the aeroderivative gas turbine from the compressor as a modular unit;   performing maintenance on at least the aeroderivative gas turbine; and   re-coupling the aeroderivative gas turbine to the compressor as a modular unit.   
     
     
         14 . The method of  claim 13 , wherein decoupling the aeroderivative gas turbine from the compressor as a modular unit comprises decoupling the first shaft of the power turbine from the second shaft of the compressor; and
 wherein re-coupling the aeroderivative gas turbine to the compressor as a modular unit comprises re-coupling the first shaft of the power turbine to the second shaft of the compressor.   
     
     
         15 . The method of  claim 8 , wherein the first and second shafts are generally axially aligned; and
 wherein each of the first and second rotational speeds ranges from about 2,000 revolutions per minute to about 4,000 revolutions per minute.   
     
     
         16 . A method of performing maintenance on a gas liquefaction system, the method comprising:
 providing the gas liquefaction system comprising a compressor and an aeroderivative gas turbine coupled thereto, the aeroderivative gas turbine comprising a gas generator and a power turbine coupled thereto;   decoupling the aeroderivative gas turbine from a remainder of the gas liquefaction system as a modular unit;   performing maintenance on at least the aeroderivative gas turbine; and   re-coupling the aeroderivative gas turbine to the remainder of the gas liquefaction system as a modular unit after decoupling the aeroderivative gas turbine from the remainder of the gas liquefaction system as a modular unit.   
     
     
         17 . The method of  claim 16 , wherein the aeroderivative gas turbine comprises an inlet for receiving air into the gas generator;
 wherein the power turbine comprises:
 an exhaust for discharging gas from the power turbine, wherein the exhaust is fluidicly coupled to the inlet when the aeroderivative gas turbine is in the form of the modular unit, and 
 a first shaft; 
   wherein the compressor comprises a second shaft directly coupled to the first shaft of the power turbine when the aeroderivative gas turbine is coupled to the compressor; and   wherein decoupling the aeroderivative gas turbine from the remainder of the gas liquefaction system as a modular unit comprises:
 decoupling the inlet of the gas generator from means via which the air is adapted to be directed to the gas generator; 
 decoupling the exhaust of the power turbine from means via which the gas is adapted to be directed away from the power turbine; and 
 decoupling the first shaft from the second shaft. 
   
     
     
         18 . The method of  claim 17 , wherein re-coupling the aeroderivative gas turbine to the remainder of the gas liquefaction system as a modular unit comprises:
 re-coupling the inlet of the gas generator to the means via which the air is adapted to be directed to the gas generator;   re-coupling the exhaust of the power turbine to the means via which the gas is adapted to be directed away from the power turbine; and   re-coupling the first shaft to the second shaft.   
     
     
         19 . The method of  claim 18 , further comprising:
 converting at least a portion of a fluid from a gas state into a liquid state, the fluid in the gas state comprising natural gas, the fluid in the liquid state comprising liquefied natural gas;   wherein converting at least a portion of the fluid from the gas state to the liquid state comprises:
 subjecting the fluid to one or more cooling stages, comprising:
 receiving fluid into a heat exchanger fluidicly coupled to the compressor; 
 removing heat from the fluid using the heat exchanger; and 
 discharging the fluid from the heat exchanger; 
 
   and   wherein removing heat from the fluid using the heat exchanger comprises:
 circulating a refrigerant through a loop, the loop comprising the heat exchanger and the compressor; and 
 transferring heat from the fluid and to the refrigerant during circulating the refrigerant through the loop, comprising:
 transferring heat from the fluid and to the refrigerant using the heat exchanger; and 
 pressurizing the refrigerant with the compressor, comprising:
 directly driving the compressor using the aeroderivative gas turbine, comprising: 
  rotating the first shaft of the power turbine at a first rotational speed; and 
  rotating the second shaft of the compressor at a second rotational speed; 
  wherein the first and second rotational speeds are substantially equal. 
 
 
   
     
     
         20 . The method of  claim 16 , further comprising:
 coupling a spare aeroderivative gas turbine to the remainder of the gas liquefaction system as a modular unit;   operating the gas liquefaction system with the spare aeroderivative gas turbine; and   decoupling the spare aeroderivative gas turbine from the remainder of the gas liquefaction system as a modular unit.