Abstract: The amount of N.sub.2 O in flue gases discharged from a fluidized bed combustion system is minimized by adding an N.sub.2 O decomposing catalyst in a reactor stage downstream of the combustor. The catalyst preferably is a calcium based sorbent, such as CaO or or limestone, although NiO and other catalysts also may be utilized. Typically, the N.sub.2 O decomposition takes place without increasing the temperature of the flue gases above the 700.degree.-1000.degree. C. level that exists combustor. However, under some circumstances, if a second fluidized bed is provided as the reactor stage, additional fuel and oxygen can be added to increase the temperature of the flue gases to insure that it is over 800.degree. C. After N.sub.2 O decomposition, the flue gases may be passed through pressurized filter tubes, or through a superheater, economizer, air preheater, optional cyclone separator, and baghouse filter.

Abstract: A circulating fluidized bed reactor comprises a separator including a vortex chamber adjacent the top of the reactor for separating solid material from the flue gases of the reactor. A channel directs flue gases discharged from the reactor and adjacent the top of the reactor in a downward direction. A main portion of the solid material is separated from the gases by a change of flow direction after which the solid material is returned to the lower part of the reactor. The main portion of the gases is directed, after the change of direction, to the vortex chamber where further separation of solid material is effected and the separated solid material is returned to the reactor.

Abstract: The invention relates to a circulating fluidized bed reactor comprising a particle separator (9) having a horizontal vortex chamber (23). The separator is preferably disposed on top of the combustion chamber (5). The pipes (25) discharging gas from the vortex chamber have been connected to openings (24) disposed on the periphery (19) of the vortex chamber.