Abstract
Fluidized bed combustion has been studied as a way for utilizationof petroleum pitch which is secondary product in the cracking processes of residual oil. Combustibility and combustion efficiency, effects of staged combustion and division of secondary air on the NOx formation, desulfurization by limestone and effect of NaCladdition to limestone were studied. The following test results were obtained.
1) Petroleum pitch had higher ignition temperature and less combustibility in com-parison with Taiheiyo coal, and so combustion efficiency became few percent lower than that of Taiheiyo coal.2) Increasing bed temperature enhanced NOx abatement in the two staged combustion.3) A significant farther reduction in NOx formation was achieved by dividing secondary air into three parts and injected into free boad, and then unburned substance in flue gas, such asCO and hydrocarbon, disappeared.4) SO2 capture by limestone increased with increasing of first stage stoichiometric air ratio. Increasing bed temperature above 850° caused a rapid lowering in desulfurization, and enhanced the decrease of SO2 capture by limestone in the low range of first stage stoichiometric air ratio.5) SO2 capture by limestone could be increased by adding NaCl to limestone.
