Fuel control method and fuel control apparatus for gas turbine and gas turbine

Abstract

A fuel control method for a gas turbine with a combustor being formed of at least two groups of a pluralities of main nozzles for supplying fuel, and that supplies fuel from the main nozzles of all groups upon ignition of the combustor (S), and supplies fuel from three main nozzles of a group A during subsequent acceleration of the gas turbine (S). Because fuel is injected from a small number of the main nozzles during acceleration, the fuel flow rate per one main nozzle is increased, thereby increasing the fuel-air ratio (fuel flow rate/air flow rate) in a combustion region and improving the combustion characteristics. Accordingly, the generation of carbon monoxide and unburned hydrocarbon is reduced, whereby no bypass valve is required and manufacturing costs are reduced. Because fuel is supplied from the main nozzles of all groups and burned in the entire area of the combustor upon ignition, it is possible to easily propagate a flame to all the other adjacent main nozzle groups, thereby improving the ignition characteristics of the whole gas turbine.