COMBUSTION CHARACTERISTICS OF A CIRCULATI NG FLUIDIZED-BED GAS COMBUSTOR WITH AN INTERNAL NOZZLE

A circulating fluidized bed gas combustor equipped with an internal no zzle in the bottom part of the riser for low calorific and difficult-t o-burn gases was proposed. Flue gas characteristics of the proposed sy stem were measured and discussed with regard to NO(x) emission. The ef fects of such parameters as the solid circulation rate, air ratio, par ticle temperature, particle property, ratio of the gas flow from the n ozzle to the total gas flow and combustion load on NO(x) emission were investigated. It was possible to decrease NO(x) emission by use of th is equipment due to the following factors. a decrease of the bed tempe rature by circulating solid particles, bed temperature control by oper ation with a suitable air ratio, high heat transfer in the bed due to high heat capacity of solids, a decrease of the bed temperature and th e two stage combustion effect by control of the ratio of gas flow from the nozzle to total gas flow.