MOTIVE POWER SUPPLY SYSTEM FOR PLANT, METHOD FOR OPERATING THE SAME, AND METHOD FOR MODIFYING THE SAME

摘要

A motive power supply system for a plant includes a gas turbine machine (20), an exhaust heat recovery boiler (3) to generate vapor with exhaust gas from the gas turbine machine, a vapor turbine machine (25) which is driven with vapor from the exhaust heat recovery boiler, a bleed piping (64) to supply vapor bled from the vapor turbine machine to a water manufacturing machine (30), a bleed air flow rate regulating valve (9) provided on the bleed piping, and a controller (110) to set up a flow rate (GblsD) of vapor bled from the vapor turbine machine in accordance with an output command deviation (?MW0) such that a total output (MW) of the gas turbine machine and the vapor turbine machine comes close to an output command value (MWD) when the output command value (MWD) from a plant which is changed with daily variation in ambient temperature drops below rated output values (MWD0) of the gas turbine machine and the vapor turbine machine. Such a configuration assures operation of the gas turbine machine in the vicinity of its rated output even in the event of drop in ambient temperature, thereby allowing to improve efficiency of the motive power supply system for a plant.