Control system, gas turbine, power generation plant, and method of controlling fuel temperature

1. A control system configured to control a flow rate of heated water which is supplied from a supply device of heated water for heating a fuel of a gas turbine to a fuel gas heater configured to heat the fuel by adjusting a degree of opening of a water flow rate regulator valve configured to regulate a flow rate of heated water which is recovered from the fuel gas heater to the supply device of heated water and control a temperature of the fuel which is supplied to a combustor of the gas turbine via the fuel gas heater, the control system comprising:

a first valve opening calculating unit configured to calculate a first valve opening which is a degree of opening of the water flow rate regulator valve based on a load of the gas turbine;

a third valve opening calculating unit configured to calculate a third valve opening by calculating a correction value based on a difference between a target temperature of the fuel which is supplied to the combustor of the gas turbine and the temperature of the fuel on an outlet side of the fuel gas heater and adding the correction value to the first valve opening; and

a water flow rate regulator valve control unit configured to control the degree of opening of the water flow rate regulator valve based on the third valve opening.

2. The control system according to claim 1 , wherein the control system is configured to control the flow rate of the heated water which is supplied from the supply device of heated water to the fuel gas heater by adjusting the degree of opening of the water flow rate regulator valve and a degree of opening of a dump valve configured to regulate a flow rate of heated water which is dumped to a steam condenser and control the temperature of the fuel through the control of the flow rate of the heated water, and

wherein the control system further comprises a dump valve control unit that controls configured to control the degree of opening of the dump valve based on a difference between a target flow rate of the heated water which is determined in advance based on the load of the gas turbine and an actual flow rate.

3. The control system according to claim 2 , wherein the third valve opening calculating unit is configured to calculate the correction value by feedback control.

4. The control system according to claim 2 , further comprising a second valve opening calculating unit configured to calculate a second valve opening by multiplying the first valve opening by a coefficient based on a temperature of the fuel on an inlet side of the fuel gas heater,

wherein the third valve opening calculating unit is configured to calculate the third valve opening by adding the correction value to the second valve opening instead of the first valve opening.

5. The control system according to claim 2 , wherein the dump valve control unit is configured to control the degree of opening of the dump valve using a flow rate which is less than the flow rate of the heated water passing through the water flow rate regulator valve as a target flow rate.

6. The control system according to claim 5 , wherein the dump valve control unit is configured to set a flow rate which is less than the flow rate of the heated water passing through the water flow rate regulator valve as the target flow rate when the load of the gas turbine is equal to or greater than a predetermined value.

7. A gas turbine comprising:

a compressor;

a combustor;

a turbine; and

the control system according to claim 1 .

8. A power generation plant comprising:

the gas turbine according to claim 7 ;

a steam turbine; and

a power generator.

9. A control system configured to control a flow rate of heated water which is supplied from a supply device of heated water for heating a fuel of a gas turbine to a fuel gas heater configured to heat the fuel by adjusting a degree of opening of a three-way valve, which is provided upstream in a path of the heated water in the fuel gas heater and configured to switch a proportion of the heated water sent out to the fuel gas heater and a proportion of the heated water sent out to a path bypassing the fuel gas heater, a degree of opening of a water flow rate regulator valve configured to regulate a flow rate of heated water which is recovered from the fuel gas heater to the supply device of heated water, and a degree of opening of a dump valve configured to regulate a flow rate of heated water which is dumped to a steam condenser and control a temperature of the fuel which is supplied to a combustor of the gas turbine via the fuel gas heater, the control system comprising:

a first valve opening calculating unit configured to calculate a first valve opening which is a degree of opening of the water flow rate regulator valve based on a load of the gas turbine;

a water flow rate regulator valve control unit configured to control the degree of opening of the water flow rate regulator valve based on the first valve opening;

a dump valve control unit configured to control the degree of opening of the dump valve based on a difference between a target flow rate of the heated water which is determined in advance based on the load of the gas turbine and an actual flow rate; and

a three-way valve control unit configured to control the degree of opening of the three-way valve based on a difference between a target temperature of the fuel and the temperature of the fuel on an outlet side of the fuel gas heater.

10. A control system configured to control a temperature of a fuel by controlling a flow rate of heated water which is supplied from a supply device of heated water to a fuel gas heater configured to heat a fuel of a gas turbine by adjusting a degree of opening of a water flow rate regulator valve configured to regulate a flow rate of heated water which is recovered to the supply device of heated water and a degree of opening of a dump valve configured to regulate a flow rate of heated water which is dumped to a steam condenser, the control system comprising:

a first valve opening calculating unit configured to calculate a first valve opening which is a degree of opening of the water flow rate regulator valve based on a load of the gas turbine;

a second valve opening calculating unit configured to calculate a second valve opening by multiplying a coefficient based on the temperature of the fuel on an inlet side of the fuel gas heater by the first valve opening; and

a water flow rate regulator valve control unit configured to control the degree of opening of the water flow rate regulator valve based on the second valve opening.

11. A method of controlling a fuel temperature, the method comprising causing a control system that controls a temperature of a fuel which is supplied to a combustor of a gas turbine via a fuel gas heater, which heats the fuel of the gas turbine, by adjusting a flow rate of heated water which is supplied to the fuel gas heater to perform:

controlling a flow rate of heated water which is supplied from a supply device of heated water to the fuel gas heater through a step of controlling a degree of opening of a water flow rate regulator valve that regulates a flow rate of heated water which is recovered from the fuel gas heater to the supply device of heated water and controlling a temperature of the fuel by the control of the flow rate of the heated water,

wherein the step of controlling the degree of opening of the water flow rate regulator valve includes:

calculating a first valve opening which is a degree of opening of the water flow rate regulator valve based on a load of the gas turbine, and

calculating a third valve opening by calculating a correction value based on a difference between a target temperature of the fuel which is supplied to the combustor of the gas turbine and the temperature of the fuel on an outlet side of the fuel gas heater and adding the correction value to the first valve opening.