METHOD FOR REMOVING NITROGEN OXIDE FROM COMBUSTION GAS IN CIRCULATION TYPE FLUIDIZED BED COMBUSTION FURNACE

摘要

PURPOSE:To provide a positive removal of nitrogen oxide 1 regardless of a combustion condition in a furnace by a method wherein either ammonia or gas containing ammonia is fed into gas having a specified range of temperature through an opening or a nozzle formed in a circumferential wall of the furnace of a circulation fluidized bed type furnace. CONSTITUTION:A chimney 7 for feeding combustion gas from an upper part of a combustion furnace 1 into a cyclone 6 is arranged and some fluidized materials accompanying combustion gas are recovered from a bottom part of the cyclone 6 and supplied in their circulated condition to a lower part of the combustion furnace 1 through a fluidized material circulation pipe 8 and a fluidized bed material moving means 9. Combustion gas separated from the fluidized materials is discharged from a top part of the cyclone 6 into the chimney 7. Ammonia feeding nozzle 13 is arranged at a circumferential wall of the circulation fluidized bed type combustion furnace 1, a flow rate of ammonia sent from an ammonia supplying device 14 is adjusted by a control device 12 for controlling an amount of ammonia and then it is fed into the furnace from the nozzle 13. At this time it is necessary that a temperature of the combustion gas is in a range of 700 deg.C to 1,200 deg.C and this range of temperature is efficient for removing nitrogen oxide. Air of two stage combustion can be supplied from the duct 4 as required for combustion.