Three-dimensional Two-phase Flow Numerical Simulation Of Tube Settler

Tube settler is one of the common sedimentation facilities in water treatment plants at present. However the operating rules of the sedimentation can not be fully grasped in the actual projects, because of the complexity of water flow field and concentration field variation. In summary the research of tube settler is extremely imperative.This paper establishes tube settler model of three-dimensional two-phase flow for numerical simulation. Through changing particle diameters of the water suspension, heights of the water distribution area and sump arrangement forms, analyzes the flow field, concentration field and effluent effects. The results show that, under the present conditions of this study:1. Changing the particle diameters of influent suspension within a certain range, will impact the removal of settling tank to some extent. When the suspended solids particle diameter is 30um,50um or 80um, the removal rate increased marginally, yet the sedimentation effect changes relatively larger as the suspension particle diameter increases from 80um to 120um,and this condition is beneficial for suspension precipitation.2. Increase the height of the water distribution area can appropriately improve the uniformity of water distribution, thereby increasing the removal of suspended solids. In practical projects, in order to improve the uniformity of the water distribution, National Specifications (GB50013-2006) stipulate that the design of water distribution should be above 1.5m. The simulation result shows that under normal circumstances, the water district with a height of 1.5m～1.9m is able to meet the requirements of the water quality of sedimentation tank, yet for higher water quality requirements of precipitation process, may choose the height greater than 1.9m.3. Sump arrangements affect the flow pattern in shimizu area of precipitation in certain extent. When it is arranged in the form of built-sided weir and parallel to the direction of the water flow, the flow patterns and effluent sedimentation tank of will be the best.