Coal-fueled combined cycle power generating system

Claim 1

In a combined cycle power generating plant, the method of devolatilizing coal by oxidation of a portion of the carbon content thereof in a carbonizing and gasifying reactor having a bed zone with sloping sides and a relatively small grate immediately under the area of widest separation between the sloping sides for admission of air or fluidizing oxidant and an adjustably movable dam in one of said sloping sides; which method comprises feeding, by gravity, crushed bituminous coal into said reactor and onto said grate at superatmospheric pressure, feeding air underneath said grate so as to effect fluidation or lifting of the bed of coal above said grate and floating or decanting char into a char hopper, adjusting said dam so as to control the height to which the fluidized bed will rise while ignited coal in said bed will react with air in partial combustion producing heat from said coal which will volatilize gases from the incoming coal, passing said gases through a boiler which absorbs heat therefrom, and then combusting said gases in a gas turbine, removing char from said reactor into a char hopper without leakage of reactor gases to the atmosphere, whereby a highly expanded and highly agitated fluidized coal bed will be provided which will contact a free furnace space above said bed zone to provide contact time at a controlled temperature for the gases leaving the bed, and discharging said char from said hopper onto a grate of a second boiler for generating steam for a steam turbine, combustion oxidizer for said second boiler being the exhaust gases from said gas turbine, whereby said combustion boiler produces complete combustion of said char and generates steam for said steam turbine.