Maxblend桨和多层组合桨搅拌槽内气液分散特性研究

Gas-liquid Dispersion Characteristics in A Stirred Tank with Maxblend Impeller and Multi-layer Combined Impeller

针对高密度聚乙烯淤浆聚合反应的低黏物料体系,以空气-水为研究对象,研究了Maxblend搅拌桨和利用三叶后掠式搅拌桨HQ150、抛物线圆盘涡轮式搅拌桨BTD170、三宽叶旋桨式搅拌桨KHX170、桨叶安装角度为δ=45°的斜叶圆盘涡轮式搅拌桨ZY160和平直叶圆盘涡轮式搅拌桨PY160构成的3种组合桨搅拌槽内的气液分散与传质特性。结果表明,拟合的气含率、气液相界面积和体积氧传质系数的经验关联式与实验数据吻合较好。Maxblend桨的PG/P受通气影响最小,其次是桨型组合3。通气量为0.6 vvm时,相同功耗下桨型组合3的气含率最高,Maxblend桨近壁区域的d32最小,功率较高时,桨型组合1、2、3中的近壁d32最小的是桨型组合3,气液相界面积最大的是桨型组合3,液相氧传质系数最大的是桨型组合1,桨型组合1、2、3的传质性能相当,且优于Maxblend桨。

For the low viscosity fluid of high-density polyethylene slurry polymerization reaction,using Maxblend impeller and three types of impeller combinations composed of three-blade-backswept impeller HQ150,parabolic disc turbine impeller BTD170,three blade hydrofoil impeller KHX170,pitched blade disc turbine impellers ZY160 with blade placement angle ofδ=45°,and straight blade disc turbine impellers PY160,the gas-liquid dispersion and mass transfer characteristics in the air-water stirred tank were studied.Results indicate that the fitted empirical correlations of gas holdup,gas-liquid interfacial area and volume oxygen mass transfer coefficient are in good agreement with experimental data.The ratio of gassed power to ungassed power of the Maxblend impeller is least affected under aeration conditions,followed by the impeller combination 3.At an aeration rate of 0.6 vvm,the gas holdup of impeller combination 3 is the highest under the same power consumption.At high power,the d32 near the wall of impeller combination 3 is the smallest among impeller combinations 1,2 and 3.The impeller combination 3 exhibits the largest specific interface area,whereas the impeller combination 1 demonstrates the highest liquid-phase mass transfer coefficient.The mass transfer performance of impeller combinations 1,2 and 3 is almost the same,and are all better than that of the Maxblend impeller.