Two-shaft gas turbine
View Patent ↗A 2-shaft gas turbine can suppress an increase in NOx emission from a combustor even when degradation of compressor efficiency occurs due to a decrease in performance with long-term use. The 2-shaft gas turbine has a gas generator and a power turbine, and includes a controller configured to set, in accordance with a degree of degradation of compressor efficiency computed from measured control parameters, a target speed of the gas generator at a level lower than a target speed in a state where degradation of the compressor efficiency has not occurred. The controller is configured to control the rotating speed of the gas generator on the basis of a difference between the target speed thus set and an actual rotating speed.
1. A 2-shaft gas turbine comprising:
a gas generator including a compressor provided with an inlet guide vane at an intake, a combustor for burning air compressed in the compressor and fuel to generate combustion gas, and a high-pressure turbine rotated by the combustion gas from the combustor to drive the compressor;
a power turbine rotated by discharge gas from the high-pressure turbine to drive load equipment; and
a controller configured to control rotating speed of the gas generator on the basis of a difference between a target speed and an actual rotating speed of the gas generator,
wherein control parameters of the compressor include at least an outlet temperature of the compressor,
wherein the 2-shaft gas turbine further comprises a first temperature detector for detecting the outlet temperature, and
wherein the controller is further configured to compute a degree of a compressor efficiency degradation from the control parameters and set, in accordance with the degree of the compressor efficiency degradation, due to a decrease in performance with long-term use, the target speed at a level lower than the target speed in a state where the compressor efficiency degradation has not occurred.
2. The 2-shaft gas turbine according to claim 1 ,
wherein the control parameters includes an inlet temperature, an inlet pressure and an outlet pressure of the compressor, and
wherein the 2-shaft gas turbine further comprises a second temperature detector for detecting the inlet temperature, a first pressure detector for detecting the inlet pressure, and a second pressure detector for detecting the outlet pressure.
3. The 2-shaft gas turbine according to claim 1 ,
wherein the control parameters include an angle of the inlet guide vane of the compressor and the actual rotating speed of the gas generator, and
wherein the 2-shaft gas turbine further comprises a rotation speed indicator for detecting the actual rotating speed of the gas generator.
4. The 2-shaft gas turbine according to claim 1 ,
wherein the target speed taking into account the degree of the compressor efficiency degradation has a lower limit set thereto.
5. The 2-shaft gas turbine according to claim 1 ,
wherein a time constant of the control for changing the target speed in accordance with the degree of the compressor efficiency degradation is set at a level greater than a time constant of the speed control of the gas generator exercised on the basis of a difference between the actual rotating speed and the target speed.
6. A method for operating a 2-shaft gas turbine comprising:
operating a gas generator including a compressor provided with an inlet guide vane at an intake, a combustor for burning air compressed in the compressor and fuel to generate combustion gas, and a high-pressure turbine rotated by the combustion gas from the combustor to drive the compressor; and
a power turbine rotated by discharge gas from the high-pressure turbine to drive load equipment, and
controlling rotating speed of the gas generator on the basis of a difference between a target speed and an actual rotating speed,
computing a degree of a compressor efficiency degradation from at least an outlet temperature of the compressor,
wherein, in accordance with the degree of the compressor efficiency degradation, due to a decrease in performance with long-term use, the target speed of the gas generator is set at a level lower than the target speed in a state where the compressor efficiency degradation has not occurred.