Abstract: Heat is recovered from the hot solids discharged from the combustion chamber of a fluidized bed reactor. Hot solid particles as a result of combustion are removed either in the form of ash, or particles separated from a gas stream, and are passed into indirect heat exchange relationship with water, producing hot water. The hot water is mixed with fuel or other solid material to simultaneously heat and moisten the solid material (e.g. to a moisture content of 15-50%). The heated and moistened solid material is then fed into the combustion chamber, along with fluidizing air, to establish a fluidized bed in which combustion takes place. The heat exchange may take place in a closed heat exchange vessel, and the cooled solid particles may be discharged from the vessel through a pressure reduction valve.

Abstract: A centrifugal separator for separating particles from gases is a vortex chamber composed of cooling planar plates or panels (i.e. they are distinctly non-cylindrical), having at least one gas inlet, at least one gas outlet and at least one outlet for the separated particles. The cross section of the side walls of the vortex chamber forms a distinctly non-circular gas space (e.g. a polygonal cross section), have a circularity of greater than 1, e.g. .gtoreq.1.1, and preferably .gtoreq.1.15. One or more vertical, parallel gas vortices may be created in the vortex chamber, the gas introduced into vertical narrow slots. The outlets for separated particles are not on the same symmetrical axes as the outlets for purified gas. Two adjacent vortices may be provided in a common rectangular chamber. The separator is preferably in conjunction with a circulating fluidized bed reactor.

Abstract: A method and apparatus are provided for effecting bidirectional feeding of particulate material, such as in the bidirectional feeding of fuel to a circulating fluidized bed combustor. A feeder has a housing with at least one inlet in the upper portion of the housing and a chain and flight (drag chain) conveyor disposed within the housing. An intermediate plate is disposed between the upper and lower runs of the chain and flight conveyor and cooperates with the flights in the upper run so that the upper run conveys solid material in a first direction along the intermediate plate. A bottom plate is disposed below the lower run and cooperates with the lower run flights to convey solid material in a second direction opposite the first direction. First and second outlets are provided for the solid material, the first outlet at one end of the housing, and the second outlet at the other end of the housing.