新型双搅拌高效澄清萃取槽中多相流体动力学的数值模拟

Numerical Simulation on Multiphase Fluid Dynamic in High Efficient Clarification and Extraction Tank with Double Stirring

采用k-ε湍流模型与Eulerian多相流模型耦合,选择Morsi-Alexander相间曳力模型,对高效澄清萃取槽中液-液两相流做了数值模拟。对不同条件下萃取槽水相出口中油相杂质含量做了详细考察。结果表明:在不同入口流量、不同澄清室搅拌转速、不同搅拌桨离底高度条件下物理实验与数值模拟所得到的水相出口油相杂质含量整体趋势保持一致。澄清室增加搅拌装置能有效降低水相出口油杂质含量,加速油、水两相的澄清分离。通过数值模拟确定了实验条件水油两相入口流量分别为40和80 L·h-1、搅拌转速10 r·min-1、澄清室内搅拌桨离底高度9 cm时水油两相达到了最佳的澄清分离效果。在其他条件一定的情况下,粘度越低,两相间界面张力越小,沉降分离效果越明显。而粘度越高,两相间界面张力越大,搅拌加速分离的效果越明显。

The liquid-liquid two phases flow in the high efficient clarification and extraction tank was numerically simulated using standard k-ε turbulent model coupled with Eulerian multiphase flow model and the Morsi-Alexander drag model. The ratio of oil in the water phase of outlet was detailedly investigated in different conditions. The results demonstrated that the oil content in water phase out- let with different inlet flow rates, rotational speeds and impeller off-bottom distances showed good agreement between experiment and simulation. After adding stirring of impeller in clarification chamber, the oil content in water phase of outlet decreased, meanwhile the separation process for clarification was accelerated. The optimum inlet flow rates of water and oil were 40 and 80 L·h^-1 , respectively, the rotational speed was 10 r·min^-1 and the impeller off-bottom distance was 9 cm, and then the best clarification and separation effects could be obtained in this condition. Under the same conditions, the settling separation was more effective for fluids with lower viscosity and thus smaller interface tension. In contrast, for the fluids with higher viscosity and interface tension, the stirring separation was more efficient.