Abstract: Slurry process is the main production method for high-density polyethylene. For slurry of high-density polyethylene stirred polymerizer, three-blade-backswept impeller HQ, parabolic disc turbine impeller BTD, three blade hydrofoil impeller KHX, pitched blade disc turbine impellers ZY with blade placement angle of δ=45° and δ=75°, and straight blade disc turbine impellers PY160 were used to form four types of impeller combinations. Solid-liquid suspension experiments were conducted in a cylindrical perspex stirred tank with a diameter of T=480 mm. The CFD software Ansys Fluent 2020R2 combined multiple reference frame method and Euler-Euler multiphase flow model were used to study the solid-liquid suspension of each impeller combination at 30.71% solid holdup. The results showed that when the rotating speed N≤ 250 r/min, a clear liquid layer formed at the top of the mixing tank with impeller combination 2 and 3. Due to the inhomogeneous of solid holdup, the power of impeller combination 3 and 4 showed an inflection point at the rotating speed N=350 r/min. When the rotating speed N≤350 r/min, the combined power of each paddle type from low to high was: 2, 4, 3, 1. When the rotating speed N>350 r/min, the mixing power from low to high was: 2, 3, 4, 1. Impeller combination 1 and 4 can achieve uniform mixing at lower speeds and power, and the power consumption of impeller combination 4 was about 30% lower than that of impeller combination 1, so impeller combination 4 was high efficiency and energy conservation. The simulated results of solid holdup were in good agreement with the experimental values which was measured by the sampling method. The simulated flow field indicated that the flow patterns of impeller combination 4 and 1 were similar, which can effectively avoid the clear liquid layer appearing in impeller combination 2 and 3 at low rotating speeds.

Key words: slurry polymerization, impeller combination, solid-liquid suspension, two-phase flow, numerical simulation

摘要： 针对高密度聚乙烯搅拌式聚合釜物料体系，利用三叶后掠式搅拌桨HQ、抛物线圆盘涡轮式搅拌桨BTD、三宽叶旋桨式搅拌桨KHX、桨叶安放角δ分别为45°和75°的斜叶圆盘涡轮式搅拌桨ZY和平直叶圆盘涡轮式搅拌桨PY构成四种桨型组合，在直径T=480 mm的圆柱形有机玻璃搅拌槽内进行了固液悬浮实验。基于计算流体力学软件Ansys Fluent 2020R2，采用多重参考系法以及欧拉-欧拉多相流模型，研究了各桨型组合在30.71%固含率下的流场和固液悬浮状态。研究结果表明，转速小于250 r/min时，桨型组合2和3在搅拌槽内顶部会形成清液层；桨型组合1和4能在更低转速和更低功率的情况下达到物料的均匀混合状态，且桨型组合4比桨型组合1的功率消耗降低约30%，具有高效节能的效果。模拟获得的固含率分布趋势与实验所测数值吻合较好。模拟的流场表明桨型组合4和1的流型相似，可以有效避免桨型组合2和3在低转速下出现的清液层。

关键词: 淤浆聚合, 桨型组合, 固液悬浮, 两相流, 数值模拟