Retrofitting Boilers and Gas Turbines

For O2/CO2 Combustion

Revised August 2011.  Hydrocarbon-fueled Rankine-cycle boilers and Brayton-cycle gas turbines, rated 5 to 300 megawatts, may be economically retrofitted for O2/CO2 combustion with increased fuel efficiency and greater power output.  By our method, all of the exhaust gas is recovered, the condensate is separated and the carbon dioxide (CO2) may be utilized to grow biomass for fuel and other purposes.

The key to efficiency improvement in applying O2/CO2 combustion to steam boiler or gas turbine systems is to achieve virtually complete waste heat recovery.  The waste heat losses are usually about 67% of fuel heat input for power plants equipped with the best available emission control technologies.  Conversion to our method is accomplished by removing the existing boiler economizer, the electrostatic precipitator (ESP) and/or baghouse, and the sulfur oxides scrubber.  These process steps are replaced by a Gas Primer Sector which recovers the waste heat and converts the system to a condensing boiler as in U.S. Patent No. 6,907,845.

 

A similar concept may be used to add steam-generated power after a gas turbine to form a combined cycle.  We estimate potential retrofit power increases of 50% to 200% for this new O2/CO2 combustion combined cycle, depending on design.  Details are yet to be disclosed due to continuing development.  Retrofit fuel efficiency should exceed 50%.

 

CO2 Recovery and Use in O2/CO2 Combustion Boiler Retrofits

 

In an O2/CO2 combustion condensing boiler, after moisture precipitation, the exhaust gas CO2 is first available for recycling to dilute the combustion gas oxygen for temperature control; and second, for hydroponic biomass growth in a unique photosynthesis/photocatalysis water treatment system.  As proposed, all CO2 should be profitably disposed if the biomass is dried for fuel.