Gas turbine cogeneration system and method of operating the same

A method of operating a gas turbine cogeneration system,

• the gas turbine cogeneration system comprising:
• a gas turbine including a compressor, a combustor, and a turbine;
• a hydrocarbon fuel supply facility for supplying hydrocarbon gas fuel to the combustor;
• a hydrogen gas fuel supply facility for supplying hydrogen gas fuel which is fuel mainly composed of hydrogen gas to the combustor;
• a heat recovery steam generator for generating steam using exhaust gas discharged from the turbine;
• an upstream steam line for supplying the steam discharged from the heat recovery steam generator to a head end side of the combustor;
• and
• a denitration device for denitration of the exhaust gas by adding a reducing agent to the exhaust gas flowing through the heat recovery steam generator,
• the method comprising a denitration control step of outputting to the denitration device a control command to set an amount of NOx emissions at a heat recovery steam generator outlet not more than a boiler outlet target value,
• wherein the denitration control step includes generating the control command with reference to at least a first addition amount of the reducing agent obtained by calculation based on a NOx parameter which is a parameter correlated with the amount of NOx emissions at a turbine outlet.