操作条件和床结构对床层平均空隙率的影响

研究了操怍压力、操作温度和床结构特性对床层膨胀的影响,随着操作压力的提高床层膨胀比明显增大,操作温度的提高则导致床层膨胀比略有下降,在设有塔型构件、垂直管束、脊型构件Ⅰ和脊型构件Ⅱ的流化床中,床层膨胀行为与床径几乎无关,而对于自由流化床,床层膨胀尚为床径的函数。在计入上述影响因素条件下,根据系统试验数据回归得以下关联式(试验范围为U=0.1-0.8m/s,T=50-500℃,P=0.1-0.8MPa,D=57-475mmm,A、B 类颗粒):ε_f=G·(Ly/Ar)~(0.0691)根据气泡两相理论,由床层膨胀试验结果,可推出处于湍动流态化操作下的自由床和构件床的气泡平均当量直径 D_(Be)计算式:

Effect of Operating Temperature,Pressure and Internal.Baffles on the Average Voidage of Gas-Solid Fluidized Beds

Experimental study on the variation of the average voidage of gas-solid flu-idized beds with operating factors reveals that the bed expansion increases obvi-ously with increasing operating pressure and slightly with decreasing operatingtemperature.In the fluidized beds,with different internal baffles,the averagevoidage is independent of bed diameter,but becomes a function of it in freebed.Based on the experimental data,the following correlation has been found:ε_f=G(Ly/Ar)~(0.0691)where:■The experimental conditions are:U=0.1—0.8m/s,t=50—500C,P=1—8×10~5Pa,D=57—475mm,A and B powders are employed.In addition,based on the obtained equation and the two-phase model,theequation for calculating the average equivalent bubble diameter in the turbulentfluidized bed is suggested as follow:D_(B■)={[(1/(1-(ρ_P)/(ρ_B)[1-G((Ly)/(Ar))~(0.0691)])-1)(U_f-U_(mf))+U_(mf)]1/(0.711g~(1/2))}~2