【摘要】 竖流式沉淀池内的流动特性和泥水分布规律是结构、工艺设计的关键,然而其内部的流场难以通过常规的实验手段获得,且物理模型花费较大。因此建立了竖流式沉淀池内泥水分离的混合物模型,应用计算机流体动力学(computational fluid dynamics, CFD)软件对其流场和浓度场进行三维数值模拟。竖流式沉淀池内存在流动漩涡,造成靠近进水管外侧和沉降筒体内侧的流速相对较高。在高度z=2 m处的沉降筒体中部流场较好,是泥水重要的沉降分离区域。随着入口流速的增大,沉淀池内受到的扰动增大,导致处理效果变差,当流速从0.01 m/s增加到0.03 m/s的过程中,水出口的污泥去除率从96.35%下降到89.17%。大粒径的污泥颗粒在泥斗中产生了更好的沉积效果,当污泥粒径从50μm增加到200μm的过程中,污泥去除率从31.93%升高到99.92%。由此可知,采用数值模拟方法能够很好的计算得到不同工艺参数下沉淀池内的泥水分布情况和流场规律,从而为工程设计提供参数依据。更多还原

【Abstract】 The flow characteristics and sludge/water distribution in vertical flow sedimentation tank are essential to the structure and process design. However, the internal flow field is difficult to be observed through conventional experimental methods, and the physical model also costs a lot. A mixture model of sludge/water separation in vertical flow sedimentation tank was established, and the flow field and concentration field were numerically simulated in three dimensions using CFD software. The flow swirls in the vertical sedimentation tank causes that the flow rate near the outside of the inlet pipe and the inside of the sedimentation cylinder are relatively high. The flow field in the middle of the sedimentation cylinder at the height z=2 m is stable as an important sedimentation separation area for sludge and water. As the inlet flow rate increased, the disturbance in the sedimentation tank became severe, which resulted in worse treatment effect. When the flow rate increased from 0.01 m/s to 0.03 m/s, the sludge removal rate at water-outlet decreased from 96.35% to 89.17%. Large sludge particles in the sludge-container exhibited better deposition effect. When the sludge particle size increased from 50 μm to 200 μm, the sludge removal rate was enhanced from 31.93% to 99.92%. It can be seen that the numerical simulation method can be used to calculate the sludge/water distribution and flow field in vertical flow sedimentation tank under different process parameters, so as to provide a parameter basis for the engineering design.更多还原