Experimental and CFD studies of solid-liquid slurry tank stirred with an improved Intermig impeller

The improved Intermig impeller has been used in the seed precipitation tank in China, which could enhance the mixing and suspension of Al(OH)3 particles and the power consumption declined largely. The flow field, solids hold-up, cloud height, just off-bottom speed and power consumptions were investigated in solid-liquid mixing system with this new type of impeller by CFD and water experiment methods. Compared with the standard Intermig impeller, the improved one coupled with specially sloped baffles could promote the fluid circulation, create better solids suspension and consume less power. Besides lower impeller off-bottom clearance is good for solid suspension and distribution. The just-off-bottom speed was also determined by a power number criterion. Meanwhile, the predicted results were in good agreement with the experimental data.

Numerical optimization for blades of Intermig impeller in solid-liquid stirred tank

The multiphase flow in the solid-liquid tank stirred with a new structure of Intermig impeller was analyzed by computational fluid dynamics(CFD).The Eulerian multiphase model and standard k-ε turbulence model were adopted to simulate the fluid flow,turbulent kinetic energy distribution,mixing performance and power consumption in a stirred tank.The simulation results were also verified by the water model experiments,and good agreement was achieved.The solid-liquid mixing performances of Intermig impeller with different blade structures were compared in detail.The results show that the improved Intermig impeller not only enhances the solid mixing and suspension,but also saves more than 20% power compared with the standard one.The inner blades have relatively little influence on power and the best angle of inner blades is 45°,while the outer blades affect greatly the power consumption and the optimized value is 45°.

种分槽改进Intermig桨搅拌性能的实验研究

为了研究改进的Intermig桨的搅拌性能,在无挡板的氧化铝种分搅拌槽内,采用PC6D颗粒浓度测量仪对水-玻璃珠液-固体系在不同条件下的颗粒轴向和径向局部浓度进行了测量与分析.结果表明,较高的搅拌转速和体系粘度更有利于固体颗粒的悬浮.粘度μ=3.50×10-3Pa·s、转速n=172r/min时,实验浓度平均值是理论浓度平均值的1.011倍,可见该条件下实验浓度值与理论浓度值更接近,混合更均匀.

双层intermig桨式搅拌槽流动场数值模拟

搅拌器被广泛应用于许多工业过程中。本文对双层intermig桨式搅拌槽内的混合过程进行了三维模拟,采用多重参考系法(MRF)及标准k-ε模型,分析了不同工况下,桨叶直径及离底高度对流场及搅拌功率的影响,绘制了Np-Re关系图。结果表明:离底高度的变化对搅拌槽流场性能的影响非常明显,流动模拟可获得详细的流场分布及各项特性参数,计算结果可为工业搅拌过程提供工艺参考。

种分槽高性能HSG/HQG搅拌装置的研发

用fluent软件对铝酸钠氢氧化铝料浆在搅拌槽内的流动特征、桨叶搅拌效果和功率消耗等进行了数值模拟,通过小型实验槽和中型工业搅拌槽的测试验证,得到正确的数学模型和边界条件,使模拟和实测达到吻合一致。模拟计算采用多面体网格、滑移网格法和标准k-ε瑞流方程,氢氧化铝体积分数为33%。然后用fluent软件模拟得到了优化的桨叶形状等参数,开发了高性能HSG/HQG组合搅拌桨。新型搅拌桨首先应用在山西铝厂的Φ6.5×10米氢氧化铝搅拌槽,之后,东方希望氧化铝厂Φ14×35.5米种分槽上也获得应用,搅拌效果良好无沉淀结疤,节能效果显著。将HSG/HQG組合搅拌桨与大型搅拌槽使用的INTERMIG搅拌桨和CBY长薄叶搅拌桨进行性能对比。结果表明,在同样的物性参数下,HSG/HQG组合搅拌桨比INTERMIG搅拌桨和CBY长薄叶搅拌桨能耗降低40%左右,槽底部无结疤,同时具有大排量和低剪切的特点。

氧化铝厂大型搅拌槽HSG/HQG高性能搅拌技术的研发与应用

国内大型搅拌槽搅拌装置的研发与应用长期处于空白状态,只能依靠引进。现有种分槽的Intermig和CBY搅拌装置是国外搅拌装置的修改版,沉淀结疤严重导致系统产能降低、存在安全隐患,且能耗偏高。从2008年开始,采用Fluent软件模拟仿真与实验槽测试相结合的办法,开发成功氧化铝厂大型搅拌槽HSG/HQG高性能搅拌装置关键技术。上述技术从2012年开始已成功应用于多家氧化铝厂,均取得了良好的效果。与现有搅拌装置相比,能耗降低30%以上,沉淀高度大幅降低,混合均匀度提高,达到了国际领先水平。通过近3年的生产实践证明:运行稳定,节能效果显著,消除沉淀效果明显,经济、社会和环境效益显著。

CFD技术在Φ16m等大型种分槽的研究与应用

近年来，新建氧化铝生产线向大型化发展，需要开发直径中16～20m甚至更大种分槽。现有种分槽搅拌研发技术手段落后，而Intermig和CBY搅拌装置沉淀结疤严重且能耗偏高，也无法满足大型种分槽的要求。我们采用软件模拟仿真技术，用自主研发的HSG／HQG高性能搅拌装置，研发成功Ф16X（37-42）m系列种分槽。本文对中16～20m种分槽HSG／HQG和Intermig搅拌装置进行了数值模拟对比分析，结合Ф16×（37～42）m系列种分槽实际应用情况，验证了高性能搅拌仿真模拟技术准确可靠、技术先进，采用HSG／HQG高性能搅拌装置的中16m种分槽具有低能耗、低沉淀结疤等优良的使用效果。

种分槽新型高效搅拌技术研究和应用

针对目前氧化铝厂种分槽搅拌装置普遍存在的槽底沉淀多和能耗偏高等问题,本文提出采用软件模拟仿真及工业测试验证等手段,对现有种分槽搅拌装置进行优化设计,成功开发出了适用于Φ14 m、Φ16 m系列种分槽的新型搅拌装置,取得了良好的经济效益和社会效益。