Gas turbine fuel blending using inferred fuel compositions

Abstract

A system, method, and computer-readable medium for blending a fuel for use in a gas turbine are disclosed. A measurement of a heating value of a process gas and a measurement of a molecular weight of the process gas is obtained. An estimate of a composition of the process gas is obtained using the obtained measurement of the heating value and the obtained measurement of the molecular weight. A blending ratio of the process gas and a natural gas is selected based on the estimate of the composition of the process gas. The process gas and the natural gas are then blended according to the selected blending ratio to obtain a fuel mixture for use in the gas turbine.

1 . A method of blending a fuel for use in a gas turbine, comprising:
 obtaining a measurement of a heating value of a process gas and a measurement of a molecular weight of the process gas;   obtaining an estimate of a composition of the process gas using the obtained measurement of the heating value and the obtained measurement of the molecular weight;   selecting a blending ratio of the process gas and a natural gas based on the estimate of the composition of the process gas; and   blending the process gas and the natural gas according to the selected blending ratio to obtain a fuel mixture for use in the gas turbine.   
     
     
         2 . The method of  claim 1 , further comprising obtaining the estimate of the composition of the process gas using a set of linear equations relating the composition of the process gas to the measurement of the heating value of the process gas and the measurement of the molecular weight of the process gas. 
     
     
         3 . The method of  claim 2 , wherein the set of linear equations includes a set of five linear equations relating five unknown molar fractions representing component gases of the process gas. 
     
     
         4 . The method of  claim 3 , wherein the set of linear equations further including at least one additional molar fraction representing an additional component gas of the process gas, wherein the at least one additional molar fraction is a known quantity. 
     
     
         5 . The method of  claim 1  further comprising obtaining the measurement of the heating value of the process gas and the measurement of the molecular weight of the process gas using at least one of: (i) a Wobbe meter; and (ii) a process gas analyzer. 
     
     
         6 . The method of  claim 1 , further comprising controlling the blending ratio of the process gas and the natural gas based on additional measurements of the heating value and molecular weight of the process gas. 
     
     
         7 . The method of  claim 1 , further comprising determining a composition of the natural gas using a set of linear equations relating the composition of the natural gas to a measurement of a heating value of the natural gas and a measurement of a molecular weight of the natural gas. 
     
     
         8 . A system for blending fuel for use in a gas turbine, comprising:
 a device configured to obtain a measurement of a heating value of a process gas and a measurement of a molecular weight of the process gas; and   a processor configured to:
 obtain an estimate of a composition of the process gas using the obtained measurement of the heating value and obtained measurement of the molecular weight; 
 select a blending ratio of the process gas and a natural gas based on the estimate of the composition of the process gas; and 
 blend the process gas and the natural gas according to the blending ratio to obtain a fuel mixture for use in the gas turbine. 
   
     
     
         9 . The system of  claim 8 , wherein the processor is further configured to obtain the estimate of the composition of the process gas using a set of linear equations relating the composition of the process gas to the measurement of the heating value and the measurement of the molecular weight. 
     
     
         10 . The system of  claim 9 , wherein the set of linear equations includes a set of five linear equations relating five unknown molar fractions representing component gases of the process gas. 
     
     
         11 . The system of  claim 10 , wherein the set of linear equations further includes at least one additional molar fraction representing an additional component gas of the process gas, wherein the at least one additional molar fraction is a known quantity. 
     
     
         12 . The system of  claim 8 , wherein the device further comprises at least one of: (i) a Wobbe meter; and (ii) a process gas analyzer. 
     
     
         13 . The system of  claim 8 , wherein the processor is further configured to control the blending ratio of the process gas and the natural gas based on additional measurements of the heating value and molecular weight of the process gas. 
     
     
         14 . The system of  claim 8 , wherein the processor is further configured to determine a composition of the natural gas using a set of linear equations relating the composition of the natural gas to a measurement of a heating value of the natural gas and a measurement of a molecular weight of the natural gas. 
     
     
         15 . A non-transitory computer-readable medium including a set of instructions stored thereon that when accessed by a processor enable the processor to perform a method for blending fuel for use in a gas turbine, the method comprising:
 obtaining a measurement of a heating value of a process gas and a measurement of a molecular weight of the process gas from a measurement device;   obtaining an estimate of a composition of the process gas using the obtained measurement of the heating value and the obtained measurement of the molecular weight;   selecting a blending ratio of the process gas and a natural gas based on the estimate of the composition of the process gas; and   blending the process gas and the natural gas according to the blending ratio to obtain a fuel mixture for use in the gas turbine.   
     
     
         16 . The non-transitory computer-readable medium of  claim 15 , wherein the method further comprises obtaining the estimate of the composition of the process gas using a set of linear equations relating the composition of the process gas to the measurement of the heating value and the measurement of the molecular weight. 
     
     
         17 . The non-transitory computer-readable medium of  claim 16 , wherein the set of linear equations includes a set of five linear equations relating five unknown molar fractions representing component gases of the process gas. 
     
     
         18 . The non-transitory computer-readable medium of  claim 17 , wherein the set of linear equations further includes at least one additional molar fraction representing an additional component gas of the process gas, wherein the at least one additional molar fraction is a known quantity. 
     
     
         19 . The non-transitory computer-readable medium of  claim 15 , wherein the method further comprises obtaining the measurement of the heating value of the process gas and the measurement of the molecular weight of the process gas from at least one of: (i) a Wobbe meter; and (ii) a process gas analyzer. 
     
     
         20 . The non-transitory computer-readable medium of  claim 15 , wherein the method further comprises determining a composition of the natural gas using a set of linear equations relating the composition of the natural gas to a measurement of a heating value of the natural gas and a measurement of a molecular weight of the natural gas.