GAS TURBINE GAP CONTROL DEVICE, GAP CONTROL METHOD, AND GAS TURBINE WITH GAP CONTROL DEVICE

PROBLEM TO BE SOLVED: To provide a gas turbine gap control device having high reliability to gain high heat efficiency in a partial load.SOLUTION: A gap control device controls a gap between an interior surface of a casing and a turbine of a gas turbine comprising a casing for enveloping the turbine, a fuel flow amount adjustment valve, and a gas turbine controller for output of a fuel flow amount command to control the output of an electric generator. The device includes: a casing cooling device for cooling the casing to adjust the gap; a flow amount adjustment valve for adjusting an amount of cool air supplied to the casing cooling device; a flow amount controller for controlling the amount of the cool air; a means for output of a supply start command of the cool air to the flow amount adjustment valve to control minimizing the gap; and a means for output of a supply stop command or a flow amount reduction command of the cool air to the flow amount adjustment valve to control the increase of the gap when the fuel flow amount command to increase the output of the electric generator is input.