Experimental Research on the Corner Secondary Air Injection of Square Circulating Fluidized Bed

Abstract-Corner secondary air injection which four nozzles respectively located on four corners of square circulating fluidized bed (CFB) was investigated in this study. The cold CFB model has a square cross-section of 0.25 m × 0.25 m and a height of 6.07 m. The axial pressure drop profile along the riser has been got by differential pressure measurement to evaluate the axial solids concentration distribution in different operating conditions. Solids concentration increases significantly below the secondary air injection ports especially when high secondary air rate is adopted. Using CO₂ as tracer, the dispersion of corner secondary air jet was investigated. It is found that if the solids concentration near nozzles´ outlet is lean, the secondary air injection with high velocity will make a swirling flow in the riser. However, higher solids concentration distribution especially in the corner region will limit the penetration of secondary air injection and no apparent swirling flow was found in these conditions.