溢流管式多层气固流化床稳定操作气速范围的影响因素

在四段溢流管式多层流化床装置中研究了固体颗粒加料速率、分布板开孔率及孔径、溢流管内径、颗粒种类及粒径对多层流化床稳定操作气速范围的影响. 结果表明，多层流化床最小稳定操作气速(Umin)随颗粒加料速率、分布板开孔率及颗粒粒度增大而增大，随溢流管管径增大而减小，与分布板孔径大小无关；最大稳定操作气速(Umax)随分布板开孔率和孔径及颗粒粒度增大而增大，随溢流管管径增大而减小. 石英砂和煤颗粒的最大稳定操作气速均先随加料速率增加而增加，超过某一加料速率(表观颗粒速度约为1.0′10-4 m/s)后基本保持不变. 在相同固体加料速率下，石英砂的最大与最小稳定操作气速比(Umax/Umin)约是煤颗粒的3倍，表明石英砂比煤颗粒具有更大的操作弹性，可能是由于使用的褐煤含水量高、流动性差所致.

Gas Velocity Range of Stable Operation in a Gas-Solid Multistage Fluidized Bed with Overflow Standpipes

The variation of gas velocity range of stable operation with major configuration and operating parameters in a gas-solid four-stage fluidized bed with overflow standpipes was studied.The tested parameters included the particle feeding rate,opening ratio and orifice size of gas distributor,inner diameter of overflow standpipe,and type and size of particles.The results showed that the minimal gas velocity(Umin) for stable operation increased with increase in the particle feeding rate,opening ratio of gas distributor and size of the treated particles,while it decreased with increase of the inner diameter of overflow standpipes and was independent of the orifices size of gas distributor.The maximal gas velocity(Umax) of stable operation increased with increase of the particle size and opening ratio and orifices size of gas distributor but decreased with increase of the inner diameter of overflow standpipes.For the tested silica sand and coal particles,Umax increased with increase of the particle feeding rate,but it was almost a constant when the superficial particle velocity was over 1.0×10-4 m/s.The threshold gas velocity ratio(Umax/Umin) of silica sand was about 3 times of that of coal,indicating that the operation flexibility of gas velocity for silica sand was higher than that of coal probably due to the poor particle fluidity of coal with high moisture.