Method of maintaining a nominal working temperature of flue gases in a PFBC power plant

A method for maintaining a nominal working temperature of flue gases during operation of a PFBC power plant having a pressure vessel with a combustor enclosed therein for combustion of a fuel in a fluidized bed, a gas turbine for receiving flue gases formed during the combustion in the combustor, a compressor driven by the gas turbine for compression of air which is utilized as combustion air during the combustion in the combustor, and a steam turbine driven by steam generated in tube bundles in the bed, comprising the steps of:

• a) injecting a complementary fuel into the combustor downstream of the tube bundle during at least normal operation of the PFBC power plant;
• and
• b) burning said complementary fuel in oxygen residues contained in said flue gas as oxidizing agents during combustion of the complementary fuel whereby increasing the flue gas temperature to a nominal level for the process.