Patent ID: 8806873

Claim:
A method for operating a gas turbine plant having a compressor, a first combustion chamber followed by a high pressure turbine, a second combustion chamber, and a low pressure turbine, the method comprising: defining a prefixed emission limit for the gas turbine plant; injecting and combusting a first gaseous fuel in the first combustion chamber, generating first hot gases and non-combusted products above the prefixed emission limit; at least partly expanding the first hot gases in the high pressure turbine; injecting and combusting a second fuel in the at least partially expanded first hot gases in the second combustion chamber, generating second hot gases; expanding the second hot gases in the low pressure turbine; injecting water at least in the first combustion chamber to increase the gas turbine plant power output; wherein injecting water comprises injecting in the first combustion chamber at a water flow rate such that flame stability in the first combustion chamber does not pass a predetermined flame stability limit; and regulating flame temperature in the second combustion chamber to burn non-combusted products generated in the first combustion chamber to bring the amount of non-combusted products below a predetermined emission limit, and without exceeding a predetermined NO x emission limit.