Abstract: A fluidized bed apparatus suitable for the combustion of fuel has a baffle assembly arranged in the freeboard above the fluidized bed level. The assembly is in the form of a perforate duct which defines within it a passage connecting with the gas exit of the apparatus. Gases issuing from the bed, in use, and carrying bed material impinge upon the duct and are arranged to follow a vortical path around the duct, resulting in a deceleration of the particles which fall back into the bed. The gases pass into the duct for exhaust substantially free from contamination by bed material. The baffle assembly is of particular value where a gas flows horizontally to a gas exit and prevents or substantially reduces elutriation.

Abstract: A hot gas is generated by passing the gas to be heated through a fluidized heating bed to fluidize the bed and to receive heat from the bed to which hot bed material is circulated from an adjacent fluidized combustion bed. An intermediate combustion bed may be interposed between the heating and combustion beds to burn any burnt matter prior to its passage to the heating bed thereby avoiding or reducing contamination of the gas to be heated.