六回路循环流化床颗粒浓度及循环流率实验研究

在六回路循环流化床冷态实验台上,采用差压法和积料法分别测定床内的颗粒浓度分布和物料循环流率,实验研究运行参数对颗粒浓度分布和循环流率的影响规律。结果表明,六回路CFB颗粒浓度分布与单回路CFB相似,沿炉膛高度呈下浓上稀的分布,炉膛出口区的颗粒浓度和速度决定了物料循环流率。当空截面气速增加时,炉膛出口区的颗粒浓度和速度均增大,六回路的循环流率大幅度增加。当二次风率小于30%时,对颗粒浓度和循环流率影响不大。颗粒浓度和循环流率随静止床高增加而增加。颗粒粒径增大时,密相区颗粒浓度增加,稀相区颗粒浓度减小,循环流率减小。基于炉膛出口区颗粒浓度和颗粒速度计算的循环流率理论值与实验数据比较吻合。

Experiment Study on Solids Suspension Density and Solids Circulating Rate in a CFB With Six Circulating Loops

Experimental studies were conducted on the gas-solid flow and solid circulating rate in a cold circulating fluidized bed(CFB) test rig with six circulating loops.The solids suspension density distribution and solid circulating rate were measured by the pressure difference method and the particle stack method.Meantime,the effects of operating parameters were studied.The results show that,similar with the single loop CFB,the solids suspension density decreases with the increasing height in the CFB with six circulating loops.The solid circulating rates are determined by the solids density and particle velocity at the riser outlets.When the superficial gas velocity increases,the solid circulating rate increases significantly because the solids density and particle velocity both increase.The solids density at the riser outlets and the solid circulating rate both decrease with the increasing of secondary air ratio and decreasing of static bed height.But the secondary air ratio has no significant effect when it is below 30%.The particle size has significant influence on the distribution of solids density and the solid circulating rate.The solid circulating rate from the calculation based on the solids density and particle velocity are in accordance with the experimental data.