Method for optimizing the operating efficiency of a fossil fuel-fired power generation system

A method of operating a fossil fuel-fired power generation system in order to thereby optimize the operating thermal efficiency thereof comprising the steps of:

• a. providing a fossil fuel-fired stem generator having a burner region and a gas pass;
• b. effecting the combustion of fossil fuel and air within the burner region of the fossil fuel-fired stem generator such that gases of combustion are produced therefrom and are made thereafter to flow to the gas pass of the fossil fuel-fired steam generator;
• c. providing a first heat transfer surface in the gas pass of the fossil fuel-fired steam generator downstream of the burner region of the fossil fuel-fired steam generator and in gas flow relation therewith;
• d. providing an air preheater downstream of the first heat transfer surface;
• e. providing duct work in the form of a first section, a second section and a third section thereof interconnecting the first heat transfer surface to the air preheater in gas flow relation therewith;
• f. providing for the gases of combustion produced within the burner region of the fossil fuel-fired steam generator a first flow path from the burner region of the fossil fuel-fired steam generator to and through the first heat transfer surface located in the gas pass of the fossil fuel-fired steam generator and through the first section, second section and third section of duct work to the air preheater;
• g. providing an interconnection upstream of the first heat transfer surface from the gas pass of the fossil fuel-fired steam generator to the second section of duct work;
• h. providing for the gases of combustion produced within the burner region of the fossil fuel-fired steam generator a second flow path from the burner region of the fossil fuel-fired steam generator through the interconnection from the gas pass of the fossil fuel-fired steam generator to the second section of duct work and from the second section of duct work through the third section of duct work to the air preheater;
• i. sensing the temperature of the gases of combustion exiting front the air preheater;
• and
• j. controlling the temperature of the gases of combustion exiting from the air preheater by controlling in response to sensing the temperature of the gases of combustion exiting from the air preheater the extent to which the gases of combustion produced within the burner region of the fossil fuel-fired steam generator flow along the first flow path from the burner region of the fossil fuel-fired steam generator to the air preheater and the extent to which the gases of combustion produced within the burner region of the fossil fuel-fired steam generator flow along the second flow path from the burner region of the fossil fuel-fired steam generator to the air preheater in order to thereby optimize the operating thermal efficiency of the fossil fuel-fired power generation system while at the same time ensuring that the air preheater is protected against corrosion caused by the temperature of the gases of combustion exiting from the air preheater falling below the acid dewpoint temperature.