Emission characteristics of co-combustion of a low calorie and high-sulfur-lignite coal and woodchips in a circulating fluidized bed combustor: Part 2. Effect of secondary air and its location

Increasing SAR lowered the recirculation rate which was followed by an increase in temperature of the dense phase and a decrease in the temperature of the dilute phase in the combustor. CO emissions were increased for the co-combustion of 30% by wt. woodchips and lignite, and for SAR greater than 15%. Increasing SAR caused cyclone outlet temperature to decrease and this indirectly increased the CO emissions. NO emission decreased with increasing SAR. It was observed that the location of SA given into the combustor had a distinctive effect on NO emission especially for SA higher than 15% for the co-combustion of 30% by wt. woodchips with lignite coal. NO emissions increased with the increase in woodchips share in fuel mixture. While SO2 emissions increased with SAR in all cases for the co-combustion of 30% by wt. woodchips, they did not change too much with SAR up to 20% for the co-combustion of 50% by wt. woodchips with coal.