Parallel staged fluidized bed combustor

Claim 1

A combustor comprising a vessel, means for dividing said vessel into two cells, means for passing air through a bed of particulate material including fuel disposed in each of said cells at a velocity sufficient to fluidize said particulate material and promote the combustion of said fuel, means for controlling the quantity of air introduced to one of said cells so that it is sufficient for complete combustion of the fuel in said latter cell to form a flue gas, means for controlling the quantity of air introduced to the other cell so that it is insufficient for complete combustion of said fuel but sufficient to generate a combustible off-gas, the flue gases from said combustion passing through said vessel and entraining a portion of said particulate material, outlets associated with said vessel for discharging said flue gas and said off-gas respectively, separating means respectively connected to said outlets for separating the entrained particulate material from said flue gases and from said off-gas, and means connected to said separators for burning said separated off-gas in the presence of said separated flue gases to raise their temperature.