COAL COMBUSTION STUDIES IN A FLUIDIZED-BED TEST FACILITY

A fluidized-bed combustor has been designed, constructed, installed, a nd tested for the combustion of coal. A cylindrical (0.152 m i.d.) flu idized-bed, equipped with a specially designed propane burner to prehe at the inert bed of sand and ignite an Illinois Basin coal sample (IBC -103), was employed in the test runs. The flue-gas composition is esta blished by using a Cole-Parmer KM 9004 electronic combustion analyzer. A methodology is developed to compute the percentage utilization effi ciency of carbon and the fuel-combustion efficiency, based on knowledg e of fuel and flue-gas compositions and operating conditions of the co mbustor. Thirteen combustion-test results are reported, emphasizing th e quality and efficiency of combustion for different coal-feed rates ( 0.66-1.58 g/s), bed temperatures (1003-1216 K), fractional excess air values (0.48-1.52), and gas-fluidization numbers (1.25-3.26). In addit ion, the hydrodynamic fluidization quality of the bed has been investi gated on the basis of a series of measurements relating the calming-se ction pressure drops through the gas-distributor plates, pressure drop s across the total bed and across its two sections, and the pressure-d rop fluctuation history for various temperatures as functions of the f luidizing air velocity. These data provide bed-property parameters suc h as the minimum fluidization velocity, bed voidage, variance in bed p ressure-drop fluctuation, and variations of these properties with oper ating conditions. The results are compared with limited related experi mental data in the literature.