Experimental Investigationson Multiple Cyclones in A Circulating Fluidized Bed

摘要

Paralleled multiple cyclones are normally applied in large scale circulating fluidized bed boilers for particulate removal and solids return.Gas-solids flows are assumed to be uniform among these individual cyclones to simplify a design procedure though they are non-uniform in fact.This paper presents an experimental study on cyclone pressure drop distributions and solid circulating rates of six paralleled cyclones in a circulating fluidized bed system.These six cyclones are located asymmetrically on the left and right walls of the circulating fluidized bed.Pressure drop profiles and solid circulating rates were measured at different particle sizes,static bed heights,secondary air rates and superficial gas velocities.Experimental results show that maldistribution of gas-solid flows is caused due to the asymmetrical layout of six cyclones.Pressure drop across the middle cyclone is larger than the other two cyclones at each side of riser.The difference is less than 6 %.Solid circulating rate in the middle loop is about 3 ～ 7 % smaller than that in the side loops.Effects of superficial gas velocity,static bed material height,particle size and secondary air rate on the pressure drops across the cyclones and solid circulating rates were investigated