Combustion control device for gas turbine
View Patent ↗A combustion control device for a gas turbine is capable of controlling fuel ratios such as a pilot ratio and controlling an aperture of a combustor bypass valve in response to a combustion gas temperature at an inlet of the gas turbine in accordance with the original concept by computing a combustion load command value which is proportional to the combustion gas temperature. The combustion control device is configured to calculate a 700° C. MW value and a 1500° C. MW value based on an inlet guide vane aperture, an intake-air temperature, and an atmospheric pressure ratio, then to calculate the combustion load command value to render the combustion gas temperature at the inlet of the gas turbine dimensionless by direct interpolation based on these values and an actual measurement value of a power generator output, and to control apertures of a pilot fuel flow rate control valve, a top hat fuel flow rate control valve, and a main fuel flow rate control valve based on ratios of fuel gas to be determined based on this combustion load command value, and thereby to control fuel supplies to a pilot nozzle, a top hat nozzle, and a main nozzle.
1. A combustion control device for a gas turbine which is fitted to a gas turbine provided with a gas turbine body, a combustor having multiple types of fuel nozzles, a compressor having an inlet guide vane, and multiple fuel flow rate control valves for respectively controlling fuel supplies to the multiple types of the fuel nozzles, and which is configured to control the fuel supplies to the multiple types of the fuel nozzles by controlling apertures of the fuel flow rate control valves, the combustion control device comprising:
first gas turbine output computing means for computing a first gas turbine output corresponding to a first combustion gas temperature at an inlet of the gas turbine based on an intake-air temperature of the compressor and an aperture of the inlet guide vane;
second gas turbine output computing means for computing a second gas turbine output corresponding to a second combustion gas temperature at the inlet of the gas turbine higher than the first combustion gas temperature at the inlet of the gas turbine based on the intake-air temperature of the compressor and the aperture of the inlet guide vane; and
combustion load command computing means for computing a combustion load command value to render the combustion gas temperature at the inlet of the gas turbine dimensionless by direct interpolation based on the first gas turbine output computed by the first gas turbine output computing means, the second gas turbine output computed by the second gas turbine output computing means, and an output of the gas turbine,
wherein ratios of fuels to be supplied respectively to the multiple types of the fuel nozzles are determined based on the combustion load command value computed by the combustion load command computing means, and the fuel supplies to the multiple types of the fuel nozzles are controlled by controlling apertures of the fuel flow rate control valves based on the ratio of the fuels.
2. The combustion control device for a gas turbine according to claim 1 ,
wherein the gas turbine includes a combustor bypass valve for adjusting a bypass amount of compressed air around the combustor, and
the bypass amount of the compressed air is regulated by controlling an aperture of the combustor bypass valve based on the combustion load command value computed by the combustion load command computing means.
3. The combustion control device for a gas turbine according to claim 1 ,
wherein the gas turbine includes gas turbine bypassing means for bypassing compressed air around any of the combustor and the gas turbine body,
the first gas turbine output computing means computes the first gas turbine output based on the intake-air temperature of the compressor, the aperture of the inlet guide vane, and a turbine bypass ratio equivalent to a ratio between a total amount of compressed air by the compressor and a turbine bypass flow rate by the gas turbine bypassing means, and
the second gas turbine output computing means computes the second gas turbine output based on the intake-air temperature of the compressor, the aperture of the inlet guide vane, and the turbine bypass ratio.
4. The combustion control device for a gas turbine according to claim 1 ,
wherein the first gas turbine output computing means computes the first gas turbine output based on the intake-air temperature of the compressor, the aperture of the inlet guide vane, and an atmospheric pressure ratio equivalent to a ratio between an intake pressure of the compressor and a standard atmospheric pressure or computes the first gas turbine output based on the intake-air temperature of the compressor, the aperture of the inlet guide vane, the turbine bypass ratio, and the atmospheric pressure ratio, and
the second gas turbine output computing means computes the second gas turbine output based on the intake-air temperature of the compressor, the aperture of the inlet guide vane, and the atmospheric pressure ratio or computes the second gas turbine output based on the intake-air temperature of the compressor, the aperture of the inlet guide vane, the turbine bypass ratio, and the atmospheric pressure ratio.
5. The combustion control device for a gas turbine according to claim 1 , further comprising:
intake-air temperature correcting means for correcting the ratios of fuels based on the intake-air temperature of the compressor.
6. The combustion control device for a gas turbine according to claim 5 ,
wherein the intake-air temperature correcting means adjusts an intake-air temperature correction amount in response to the combustion load command value.
7. The combustion control device for a gas turbine according to claim 1 ,
wherein the second gas turbine output computing means computes the second gas turbine output corresponding to a maximum combustion gas temperature equivalent to the second combustion gas temperature at the inlet of the gas turbine, and
the combustion control device comprises learning means for comparing the second gas turbine output computed by the second gas turbine output computing means and an output of the gas turbine after a judgment that the combustion gas temperature at the inlet of the gas turbine reaches the maximum combustion gas temperature based on a temperature of exhaust gas discharged from the gas turbine body and on a pressure ratio of the compressor, and correcting the second gas turbine output so as to coincide with the output of the gas turbine.