Patent ID: 6431095
Filing Date: 2002-08-13
Classification: F23C,F23L,Y02E

Abstract:
A method of improving combustion in a system of the circulating fluidized bed type, which system includes a hearth associated with at least one cyclone having an inlet connected to a top of the hearth, and operates using fuel that is inserted into a bottom of the hearth, where a reducing atmosphere is created and where the fuel undergoes pyrolysis with separation into a solid phase made up of grains of coke and of nitrogen-coke coming from the fuel, and a gaseous phase containing volatile matter including remaining nitrogen contained in the fuel, both of the phases rising up inside the hearth where combustion continues while leaving incompletely burnt particles which are sucked up and returned to the bottom of the hearth by cyclone action, said method comprising:providing primary air injection performed at the bottom of the hearth; providing at least one secondary air injection performed to create an oxidizing atmosphere in the hearth above the bottom of the hearth where a reducing atmosphere is created; and providing late air injection between the top of the hearth and the inlet of the cyclone in addition to the primary air injection performed at the bottom of the hearth, and in addition to the at least one secondary air injection, thereby modifying paths of the particles sucked up by cyclone action to increase collection efficiency of the cyclone, and thus increase combustion efficiency of the system by burning particles that would otherwise remain unburnt.