System and method for controlling a fuel supply associated with a turbomachine

Abstract

Embodiments of the present invention incorporate a relatively slow acting valve to throttle the fuel flow through the compressor. Embodiments of the present invention seek to reduce the need for recirculating compressed fuel that is not needed by the turbomachine. This may increase the net power output and efficiency of a turbomachine-fuel gas compressor system.

1 . A system for controlling fuel flowing through a fuel supply system to an operatively combined turbomachine and fuel gas compressor unit, the system comprising:
 a compressor comprising at least one stage, a recirculation circuit associated with the at least one stage, wherein the recirculation circuit is equipped with an anti-surge valve; and a flow path that allows a fuel to fluidly communicate through the compressor; and   a throttling valve that controls conditions of the fuel at the inlet of the compressor stage within the flow path; wherein the throttling valve reduces a need to recirculate additional fuel through the compressor via the recirculation circuit; wherein the throttling valve assists the compressor with operating within design conditions.   
     
     
         2 . The system of  claim 1 , wherein the throttling valve is located upstream of a first stage of the compressor and in the flow path. 
     
     
         3 . The system of  claim 1 , wherein a form of the throttling valve comprises a butterfly valve. 
     
     
         4 . The system of  claim 1 , wherein the compressor comprises a centrifugal compressor. 
     
     
         5 . The system of  claim 1 , wherein the compressor comprises an axial-flow compressor. 
     
     
         6 . The system of  claim 1 , wherein the compressor discharges the fuel to a turbomachine. 
     
     
         7 . The system of  claim 1 , wherein the compressor comprises at least two stages and an interstage area that connects each stage, wherein the flow path allows the fuel to fluidly communicate through each stage. 
     
     
         8 . The system of  claim 7 , wherein the throttling valve is located within the interstage area and in the flow path. 
     
     
         9 . A method of controlling fuel flowing through a fuel supply system to an operatively combined turbomachine and fuel gas compressor unit, the method comprising:
 providing a compressor comprising at least one stage, a recirculation circuit associated with the at least one stage, wherein the recirculation circuit is equipped with an anti-surge valve; and a flow path that allows a fuel to fluidly communicate through the compressor; and   modulating a throttling valve that controls conditions of the fuel at the inlet of the compressor stage within the flow path;   wherein the throttling valve reduces a need to recirculate additional fuel through the compressor via the recirculation circuit; wherein the throttling valve assists the compressor with operating within design conditions.   
     
     
         10 . The method of  claim 9  further comprising providing a turbomachine that receives the fuel from the compressor. 
     
     
         11 . The method of  claim 10  further comprising determining whether a permissive is satisfied. 
     
     
         12 . The method of  claim 9  further comprising:
 a. enabling the throttling valve; 
 b. controlling the throttling valve to a desired range; and 
 c. closing the anti-surge valve. 
 
     
     
         13 . The method of  claim 12  further comprising determining whether the throttling valve is within the desired range based on a change to an operating condition. 
     
     
         14 . The method of  claim 13 , wherein the operating condition comprise at least one of: load; ambient temperature; fuel temperature at an inlet of the compressor; the composition of the fuel; or the fuel pressure at the inlet of the compressor  100 . 
     
     
         15 . The method of  claim 12 , wherein the desired range is within the linear controllable range of the throttling valve. 
     
     
         16 . The method of  claim 12 , wherein the desired range is from about 0.25 bar to about 2.0 bar lower than a pressure set point of the anti-surge valve. 
     
     
         17 . The method of  claim 12 , wherein a throttling valve control loop speed is slower than other protection and pressure control loops. 
     
     
         18 . The method of  claim 12 , wherein the permissive comprises at least one of:
 a. the turbomachine is operating on a gas fuel; or   b. the turbomachine is producing useful work.   
     
     
         19 . The method of  claim 12  further comprising tuning a movement of the throttling valve to allow the anti-surge valve to move substantially faster than the throttling valve. 
     
     
         20 . The method of  claim 9 , wherein the compressor comprises at least two stages and an interstage area that connects each stage, wherein the flow path allows the fuel to fluidly communicate through each stage.