Influence of impeller diameter on local gas dispersion properties in a sparged multi-impeller stirred tank  

桨径变化对多层桨搅拌槽中气液分散局部特性的影响（英文）

作　　者：包雨云 杨杰 王冰洁 高正明 

机构地区：[1]State Key Laboratory of Chemical Resource Engineering, School of Chemical Engineering, Beijing University of Chemical Technology

出　　处：《Chinese Journal of Chemical Engineering》2015年第4期615-622,共8页中国化学工程学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(21121064,21206002,21376016)

摘　　要：Vertical distributions of local void fraction and bubble size in air-water dispersion system were measured with a dual conductivity probe in a fully baffled dished base stirred vessel with the diameter T of 0.48 m, holding 0.134 m3 liquid. The impeller combination with a six parabolic blade disk turbine below two down-pumping hy- drofoil propellers, identified as PDT ＋ 2CBY, was used in this study. The effects of the impeller diameter D, rang- ing from 0.30T to 0.40T （corresponding to D/T from 0.30 to 0.40）, on the local void fraction and bubble size were investigated by both experimental and CFD simulation methods. At low superficial gas velocity Vs of 0.0077 m· s-1, there is no obvious difference in the local void fraction distribution for all systems with different D/T. However, at high superficial gas velocity, the system with a D/TofO.30 leads to higher local void fraction than systems with other D/T. There is no significant variation in the axial distribution of the Sauter mean bubble size for all the systems with different D/T at the same gas superficial velocity. CFD simulation based on the two-fluid model along with the population balance model （PBM） was used to investigate the effect of the impeller diameter on the gas-liquid flows. The local void fraction predicted by the numerical simulation approach was in reasonable a^reement with the experimental data.Vertical distributions of local void fraction and bubble size in air–water dispersion system were measured with a dual conductivity probe in a fully baffled dished base stirred vessel with the diameter T of 0.48 m,holding0.134 m3liquid.The impeller combination with a six parabolic blade disk turbine below two down-pumping hydrofoil propellers,identified as PDT+2CBY,was used in this study.The effects of the impeller diameter D,ranging from 0.30T to 0.40T(corresponding to D/T from 0.30 to 0.40),on the local void fraction and bubble size were investigated by both experimental and CFD simulation methods.At low superficial gas velocity VSof0.0077 m·s-1,there is no obvious difference in the local void fraction distribution for all systems with different D/T.However,at high superficial gas velocity,the system with a D/T of 0.30 leads to higher local void fraction than systems with other D/T.There is no significant variation in the axial distribution of the Sauter mean bubble size for all the systems with different D/T at the same gas superficial velocity.CFD simulation based on the two-fluid model along with the population balance model(PBM)was used to investigate the effect of the impeller diameter on the gas–liquid flows.The local void fraction predicted by the numerical simulation approach was in reasonable agreement with the experimental data.

关 键 词：Impeller diameterLocal void fractionBubble sizeCFD-PBMMixing 

分 类 号：TQ051.72[化学工程] TS737.2[轻工技术与工程—制浆造纸工程]