up of the gas turbine 36 the coal gasification fuel is generated in the gasification furnace 39 in this case during the start up of the gas turbine 36 at first in the gasification furnace 39 a compressed air from the auxiliary compressor 49 or oxygen separated from the compressed air by the air separator 46 is used after the gas turbine 36 starts up the pressurized air by the gas turbine compressor 37 or oxygen separated from the pressurised air by the air separator 46 in the operation stage until about one fourth u00bc load of the gas turbine 36 from the start up operation only incomplete coal gasification fuel having a low calorific value is generated in the gasification furnace 39 and for this reason the liquid fuel operation is continued with the rise of load a complete coal gasification fuel is generated in the gasification furnace 39 and thereafter a change over is made from the liquid fuel combustion operation to a coal gasification fuel operation and then only coal gasification fuel operation is carried out by a gas turbine rating point thereafter in the case where the gas turbine 36 is in a load dump state or when the gas turbine 36 is stopped a change over is again made from the coal gasification fuel operation to the liquid fuel operation next the structure of the combustor 35 used in the coal gasification combined cycle power generation plant will be explained with reference to fig2 and fig3 as shown in fig2 a combustor 35 is constructed in a manner that a combustor liner 64 used as an.