Patent ID: 7410356

Claim:
A circulating fluidized bed boiler having improved reactant utilization, the circulating fluidized bed boiler comprising: (a) a circulating fluidized bed including: (i) a dense bed portion; (ii) a lower furnace portion adjacent to the dense bed portion; and (iii) an upper furnace portion; (b) a reactant to reduce the emission of at least one combustion product in the flue gas; and (c) a plurality of secondary air injection ports downstream of the circulating fluidized bed for providing mixing of the reactant and the flue gas in the furnace above the dense bed, wherein: i. the secondary air injection ports are positioned at a height in the furnace where the gas and particle density is less than about 165% of the furnace exit gas and particle density; and ii. the amount of reactant required for the reduction of the emission of the combustion product is reduced.