Patent ID: 8117823

Claim:
A method for controlling a temperature of a fuel gas, the method comprising the steps of: generating an intermediate pressure feedwater stream and a high pressure feedwater stream in a heat recovery steam generator using an exhaust from combustion in a gas turbine involving the fuel gas; introducing the intermediate pressure feedwater stream into a mixer; introducing the high pressure feedwater stream into the mixer; mixing in the mixer the intermediate pressure feedwater stream and the high pressure feedwater stream; outputting an output stream from the mixer; introducing the output stream into a heat exchanger; heating the fuel gas in the heat exchanger; and increasing or decreasing a mass flowrate of the high pressure feedwater stream to achieve a targeted temperature or pressure of the output stream to affect a Modified Wobbe Index of the fuel gas; and wherein the step of heating the fuel gas in the heat exchanger controls the Modified Wobbe Index and facilitates correction of +10% error in the Modified Wobbe Index of the fuel gas.