Abstract: A heat exchanger for use in a multi-solid fluidized bed heat generating system includes a housing for containing a flowing volume of hot gas and fluidized recirculating solid particulate material. The housing includes outer side walls, a top wall and an intermediate bottom structure comprising water wall panels for containing a flow of water/steam to be heated from the hot gas and solid material contained within the enclosure formed by the housing walls. A supply header is provided to direct water/steam to be heated into the water wall panels at a lower level and a takeoff header is utilized for removing the heated water/steam from the wall panels at an upper level. A fluidizing gas injector system is provided for directing a high velocity flow of gaseous fluid into the enclosure formed by the housing water wall panels at a lower level therein for fluidizing the recirculating solid particulate material, which material is recycled back into a combustion vessel of the fluidized bed heat generating system.

Abstract: A fluidized bed heat generator includes a combustion reactor vessel containing a recirculating flow of fluid entrained fine solid particulate material with a dense bed section of limited space in the vessel containing a fluidized coarse solid particulate material retained therein. A recirculating path defined in part within the vessel and externally thereof provides for a recirculating flow of said fine solid particulate material into and out of the combustion vessel and through the coarse material of the dense bed section. Air or gas is supplied for fluidizing the coarse solid particulate material in the dense bed section and for entraining the fine solid material to flow through the dense bed and around the recirculating path. A separator system is provided for maintaining both the fine solid particulate material and the coarse solid particulate material in the dense bed section within selected particle size ranges to promote maximum efficiency of operation at variable loads.