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The Temperature Control System will limit fuel flow to the gas turbine to maintain internal operating temperatures within design limitations of turbine hot gas path parts. The highest temperature in the gas turbine occurs in the flame zone of the combustion chambers. The combustion gas in that zone is diluted by cooling air and flows into the turbine section through the first stage nozzle. The temperature of that gas as it exits the first stage nozzle is known as the “firing temperature” of the gas turbine; it is this temperature that must be limited by the control system. From thermodynamic relationships, gas turbine cycle performance calculations, and known site conditions, firing temperature can be determined as a function of exhaust temperature and the pressure ratio across the turbine; the latter is determined from the measured compressor discharge pressure (CPD). The temperature control system is designed to measure and control turbine exhaust temperature rather than firing temperature because it is impractical to measure temperatures directly in the combustion chambers or at the turbine inlet. This indirect control of turbine firing temperature is made practical by utilizing known gas turbine aero– and thermo–dynamic characteristics and using those to bias the exhaust temperature signal, since the exhaust temperature alone is not a true indication of firing temperature. Firing temperature can also be approximated as a function of exhaust temperature and fuel flow (FSR) and as a function of exhaust temperature and generator output (DWATT). Either FSR or megawatt exhaust temperature control curves are used as back–up to the primary CPD–biased temperature control curve.
So it may be due high exhaust temperature from cpd problem that comprssor need cold wash or problem so may check gcv or2nd stage nozzle angle problem may it stucks
for80% compressor need cold wash u can record cpd before washing and compare with after washing
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