Abstract: Hearth and process for the fluidized bed treatment of a fuel consisting of solid particles. The grid (1) for conveying gaseous fluidization and/or forcing fluid to a treatment chamber (2) comprises two separately supplied circuits of channels, respectively a first circuit of channels (11) with orifices widened towards the top, for the fluidization of a particulate material, and a second circuit of tubular channels (14), opening out above widened orifices, for forcing the particulate material.

Abstract: Coking coal is preheated in a fluidization chamber which houses a rotary percussion grinder and into the bottom of which a vertical pipe leads from a combustion chamber. Coal is introduced into the pipe and is entrained by gas in the pipe which gas subsequently acts as fluidization agent in the fluidization chamber. A main burner and an auxiliary burner in the combustion chamber are regulated by regulating the supply of combustion air so that the gas in the pipe is substantially neutral, and regulating the fuel supply in dependence on the temperature in the fluidization chamber. Preheated ground coal entrained in gas is led from the top of the fluidization chamber, and gas is recycled to the combustion chamber in an amount so that the speed of total gas flow in the fluidized coal is constant.