Fluidized bed furnace

Claim 1

A fluidized bed furnace for coarse grained coal feed material comprising: a vessel having heat resistant walls and an inflow plate extending between said walls to form a plenum extending entirely across the bottom of the vessel, said plenum and inflow plate being formed into a plurality of rows of adjacent rectilinear zones; air nozzles in said inflow plate for providing an air feed to maintain a fluidized bed of comparatively inert material in said vessel above said plate; a plurality of coal supply pipes extending through said inflow plate into said vessel beneath said fluidized bed and above said inflow plate, one of said coal supply pipes being located in each of said zones, said coal supply pipes being connected into zone groups so located on the inflow plate as to permit part load operation of the furnace while maintaining fluidized bed temperatures, said pipes terminating in the fluidized bed below its upper boundary, said pipes being sized to supply coarse grained coal to the fluidized bed; and fuel supply means selectively communicating with said groups of coal supply pipes for forcing said coal through said pipes.