Experimental Studies on the Feasibility of In-Furnace Control of SO2and NOx Emissions from Industrial Stokers,

摘要

Ten proof-of-principle experiments were conducted to determine the feasibility of controlling emission of SO2and NOx from industrial stoker boilers by limestone to a fixed bed of coal in conjunction with the use of flue-gas recirculation,air humidification,or staged combustion. These experiments were carried out at temperatures ranging from 1800to 2400 F,with monitoring of the burning rates,bed temperatures,and flue-gas composition. The variables evaluated included flue-gas recirculation rates of,respectively, 0to 40percent, 0to 10percent,and 0to 100percent of the primary air-flow rate,fuel feed rates of 0to 60lb/hr,and limestone additions of 0to 15percent of the fuel feed rate. The SO2levels in the flue gas were significantly reduced (sulfur removals of as much as 64plus or minus 3percent) during staged combustion at 1900to 2200 F,and owing to the low combustion temperatures,NOx emissions were about half those expected in the combustion of stoker coal. From these results,it is indicated that emission of SO2and NOx may be significantly reduced from some types of stoker boilers by combining two-stage combustion with the addition of limestone to the fuel.