Abstract: A system and method are disclosed for lowering NO.sub.x levels in flue gases of a fluidized bed reactor using selective non-catalytic reduction. A reactor is connected to a separator by a duct, and a reactant is introduced into the duct for decreasing NO.sub.x levels in the flue gases passing from the reactor, through the duct, and into the separator. The reactant, such as ammonia or urea, is selectively injected into a gaseous-rich region of the duct, near an upper, inner portion of the duct, so that a high degree of mixing of the reactant with flue gases is achieved while maintaining a low degree of mixing of the reactant with the particulate materials. The point of injection of the reactant into the duct is also at a location nearer to the reactor than to the separator to provide for increased residence time. In this manner, the reactant is used efficiently while obtaining the desired lowering of NO.sub.x levels in the flue gases.

Abstract: A fluidized bed system in which a plate is disposed in an enclosure and is adapted to support particulate material. A nozzle is supported by the plate for receiving air and water and directing the air and water and into the particulate material to fluidize and cool same.

Abstract: A fluidized bed combustion system and method in which a recycle heat exchange section, including an inlet compartment and a heat exchange compartment, is located within an enclosure housing the furnace section of the combustion system. The flue gases and entrained solids from a fluidized bed in the furnace section are separated, the flue gases are passed to a heat recovery section, and the separated particulate material is passed directly to the inlet compartment via a dipleg. The recycle heat exchange section includes a bypass chamber for permitting the separated solids to pass directly from the inlet compartment to the furnace section. Heat exchange tubes are provided in the heat exchange compartment to transfer heat from the separated material in the latter compartment to a fluid flow circuit for heating the fluid flow circuit. The separated material in the heat exchange compartment is passed back to the furnace section.

Abstract: A fluidized bed combustion system and method in which a recycle heat exchanger is located adjacent the furnace section of the recycle heat exchanger. Heat exchange surfaces are provided in one compartment of the heat exchanger for removing heat from the solids, and a bypass compartment is provided through which the solids directly pass to the furnace during start-up and low load conditions. A separate cooling compartment for the separated solids is disposed in the recycle heat exchange and valves are provided to selectively control the flow of solids between compartments.

Abstract: A nozzle for use in a fluidized bed system in which a plate is disposed in an enclosure and is adapted to support particulate material. The nozzle is supported by the plate for receiving air and directing the air through the plate and into the particulate material to fluidize same. The nozzle includes a valve for permitting the flow of air through the nozzle and for preventing the backflow of particulate material.

Abstract: A fluidized bed combustion method in which a recycle heat exchanger is located adjacent the furnace of the combustion system. A mixture of flue gases and entrained particulate materials from a fluidized bed in the furnace are separated and the flue gases are passed to a heat recovery section and the separated particulate material are passed back to the furnace. The walls of the furnace are formed by water tubes, and refractory metal material is placed adjacent the walls to control the heat absorption by the water passing through the tubes. The amount of refractory is selected in accordance with the desired operating temperature of the furnace.

Abstract: A fluidized bed reactor and a method of operating same in which a bed of particulate material is supported on a grate in an enclosure. Air is passed through the grate to fluidize the particulate material and promote the combustion of the fuel. At least one separating unit is disposed adjacent each of two walls forming the enclosure for receiving the mixture of air, the gaseous products of combustion and the relative fine particulate material entrained by the air and gaseous products of combustion. Each separating unit operates to separate the particulate material from the mixture, and a distributor unit is associated with each separating unit for receiving the separated particulate material and distributing it to the bed at multiple locations.