Method for purging fuel channel, purging device for executing said method, and gas turbine installation provided with said device

A purging device for at least one fuel channel in a combustor having a nozzle that selectively sprays a liquid fuel and a gas fuel, the nozzle having formed therein a first liquid-fuel channel of the at least one fuel channel, through which the liquid fuel flows and which is open at a first tip portion of the nozzle, and a first gas-fuel channel of the at least one fuel channel, through which the gas fuel flows and which is open at the first tip portion of the nozzle, the purging device comprising:

• a water line that supplies water to the first liquid-fuel channel;
• a water adjustment valve that adjusts a flow rate of the water flowing through the water line;
• and
• a controller that controls an opening amount of the water adjustment valve,
• the controller including a fuel supply state recognition controller that recognizes a fuel supply state to the nozzle and a water purging controller that controls the opening amount of the water adjustment valve in accordance with the fuel supply state recognized by the fuel supply state recognition controller,
• the fuel supply state recognition controller recognizing a liquid fuel supply state in which, of the liquid fuel and the gas fuel, only the liquid fuel is supplied to the nozzle, a first gas fuel supply state in which, of the liquid fuel and the gas fuel, only the gas fuel is supplied to the nozzle, and a fuel switching state that is a state of transition from the liquid fuel supply state to the first gas fuel supply state,
• the water purging controller instructing a pre-switch opening amount to the water adjustment valve, which causes the water of a first flow rate value to be supplied to the first liquid-fuel channel, when the fuel supply state recognition controller recognizes that the liquid fuel supply state exists, instructing a mid-switch opening amount to the water adjustment valve, which causes the water of a second flow rate value to be supplied to the first liquid-fuel channel, when the fuel supply state recognition controller recognizes that the fuel switching state exists, and instructing a post-switch opening amount to the water adjustment valve, which causes the water to be supplied to the first liquid-fuel channel, when the fuel supply state recognition controller recognizes that the first gas fuel supply state has been reached, and
• the water purging controller causing the mid-switch opening amount to be smaller than the pre-switch opening amount so as to cause the second flow rate value to be lower than the first flow rate value, and determining the post-switch opening amount such that the water of a third flow rate value, which is higher than the second flow rate value, is at least temporarily supplied to the first liquid-fuel channel in the first gas fuel supply state.

A gas turbine plant, comprising:

• a purging device for at least one fuel channel in a combustor having a nozzle that selectively sprays a liquid fuel and a gas fuel, the nozzle having formed therein a first liquid-fuel channel of the at least one fuel channel, through which the liquid fuel flows and which is open at a first tip portion of the nozzle, and a first gas-fuel channel of the at least one fuel channel, through which the gas fuel flows and which is open at the first tip portion of the nozzle, the purging device comprising:
• a water line that supplies water to the first liquid-fuel channel;
• a water adjustment valve that adjusts a flow rate of the water flowing through the water line;
• and
• a controller that controls an opening amount of the water adjustment valve,
• the controller including a fuel supply state recognition controller that recognizes a fuel supply state to the nozzle and a water purging controller that controls the opening amount of the water adjustment valve in accordance with the fuel supply state recognized by the fuel supply state recognition controller,
• the fuel supply state recognition controller recognizing a liquid fuel supply state in which, of the liquid fuel and the gas fuel, only the liquid fuel is supplied to the nozzle, a first gas fuel supply state in which, of the liquid fuel and the gas fuel, only the gas fuel is supplied to the nozzle, and a fuel switching state that is a state of transition from the liquid fuel supply state to the first gas fuel supply state,
• the water purging controller instructing a pre-switch opening amount to the water adjustment valve, which causes the water of a first flow rate value to be supplied to the first liquid-fuel channel, when the fuel supply state recognition controller recognizes that the liquid fuel supply state exists, instructing a mid-switch opening amount to the water adjustment valve, which causes the water of a second flow rate value to be supplied to the first liquid-fuel channel, when the fuel supply state recognition controller recognizes that the fuel switching state exists, and instructing a post-switch opening amount to the water adjustment valve, which causes the water to be supplied to the first liquid-fuel channel, when the fuel supply state recognition controller recognizes that the first gas fuel supply state has been reached, and
• the water purging controller causing the mid-switch opening amount to be smaller than the pre-switch opening amount so as to cause the second flow rate value to be lower than the first flow rate value, and determining the post-switch opening amount such that the water of a third flow rate value, which is higher than the second flow rate value, is at least temporarily supplied to the first liquid-fuel channel in the first gas fuel supply state;
• the combustor;
• and
• a turbine that is driven by combustion gas generated by the combustor.