COMBUSTION CHARACTERISTICS OF SHREDDED WASTE TIRES NA FLUIDIZED-BED COMBUSTOR

Abstract

The effects of bed temperature (700-900-degrees-C), freeboard temperature (600-800-degrees-C) and excess-air ratio (0-100%) on CO, NO(x) and SO2 emissions, axial temperature profiles, and combustion efficiency of shredded waste tires have been determined in a 76.2 mm i.d. x 1.2 m high fluidized-bed combustor. CO-emission levels are maintained below 400 ppm at freeboard temperatures above 750-degrees-C with a 25% excess-air ratio. The freeboard temperature increases sharply at lower excess-air ratios or at bed temperatures below 750-degrees-C. The overall combustion efficiency for waste tires is higher than for bituminous coal and increases with increasing excess-air ratio and bed temperature. The NO(x) concentration in the flue gas based on 6% O2 has been correlated with the bed temperature, nitrogen fraction in the fuel and excess-air ratio.