COMBUSTION METHOD FOR GAS TURBINE PREMIXING COMBUSTOR

PURPOSE:To provide a combustion method for a gas turbine premixing combustor capable of controlling the generation amount of NOX by a diffusion burner without deteriorating freedom and reliability in the operation of a gas turbine during the period from the start to the rated operation of the gas turbine. CONSTITUTION:A combustor is provided with a first stage combustion chamber (I), a first stage mixing region (II), a second stage combustion chamber (III), a second stage mixing region (IV) and a third stage combustion chamber (V) which are arranged in the above order from the upstream side, and combustion gas generated in the first stage combustion chamber (I) and pre-mixed gas supplied from a downstream side are mixed with each other and pre-mixed combustion is successively effected in the second stage combustion chamber (III) and the third stage combustion chamber (V) in accordance with the load of a gas turbine. Before the pre-mixed combustion on the downstream side is effected, in the first stage combustion chamber (I) mode is switched from a combustion mode by use of diffusion fuel 28 to a diffusion/first stage pre- mixed hybrid combustion mode in which most part of the diffusion fuel 28 is diverted to primarily pre-mixed fuel 29.