压力下流化床流动特性的实验研究

Experimental study on flow characteristics of fluidized bed at elevated pressure

利用摄像技术在φ60mm×800mm压力为0.1MPa～1.5MPa的冷模加压流化床实验装置上,对两种不同粒径颗粒的最小流化速度和床层膨胀高度进行了研究。研究结果表明,大粒径聚苯乙烯颗粒的Umf与p-0.3成比例,小粒径石英砂的Umf与p-0.21成比例,并根据实验值拟合出压力下最小流化速度公式为:U_(mf)=μ/(d_pρ_g){[(34.15)~2+0.05916×(d_p^3ρ_g(ρ_s-ρ_g)g)/μ~2]1/2-34.15}床层膨胀高度随气速的增大而不断增高,在相同U-Umf下床层膨胀高度随压力的增大而增高,在大于0.7MPa时,压力对膨胀高度的影响减弱。对于聚苯乙烯颗粒,相同的H/Hmf下,U-Umf随压力的增大而逐渐减小,当H/Hmf=1.4～1.6时,U-Umf与p-0.52～p-0.58成比例。

An experimental study of the influence of pressure on Umf and bed expansion height by the photographing with a camera was carded out in a fluidized bed of 60 mm i. d. in the range of operating absolute pressure 0.1 MPa - 1.5 MPa with two kinds of different size particles. Experimental results indicate that for the polystyrene（Ps） particle with a larger size, Umf changes with p^-0.3, and for the sand particle with a smaller size, Umf changes with p^-0.21. An empirical equation about Umf is proposed based on the experimental data： U（mf）=μ/（dpρg）{[（34.15）^2＋0.05916×（dp^3ρg（ρs-ρg）g）/μ^2]1/2-34.15} It is found that the bed expansion height increases with the increasing of gas velocity, and increases with pressure for fixed value of U-Umf, when the pressure exceeds 0. 7 MPa, the influence of pressure on the bed expansion height is weakened. For the polystyrene（Ps） particle, U-Umf decreases with the increasing of pressure for fixed value of H/Hmf. When H/Hmf = 1.4-~ 1.6, U-Umf varies with p^ -0.52 -P^ -0.58.