灰水循环离心泵磨损特性的数值模拟

Numerical Simulation of Erosive Performance for Coal Ash Water Circulation Centrifugal Pump

用于输送高温高压含煤灰水的灰水循环泵是煤气化装置重要的关键设备,采用半开式叶轮和导叶式扩压器的结构是较合理和经济的方案。为揭示其磨损特性,采用Particle模型和非均相模型,对不同颗粒粒径(0.25mm和0.7mm)和浓度(1%和5%)下的内部流场进行三维湍流数值模拟。结果表明,两种粒径下叶轮内的颗粒相速度分布非常相似,磨损的位置也大致相同。磨损部位在长叶片进口边、后盖板从轴向到径向的转弯区域、长叶片工作面入口区域、长短叶片背面出口区域。随着颗粒粒径和浓度的增加,长叶片工作面的磨损部位从入口扩展到中部,长短叶片背面的磨损部位从出口扩展到整个叶片。导叶叶片螺旋线部分的颗粒相浓度高于扩散段部分。

Ash water circulating pump used for transporting high temperature and high pressure coal ash water is key equipment in coal gasification unit.Use of the structure with semi-open impeller and vane diffuser is an appropriate and economical scheme.To estimate its wear resistance performance,a numerical simulation with Particle and heterogeneous model was carried out for centrifugal pump under different particle sizes and concentrations.The results showed that the velocity distributions of particles with two different sizes in the impeller were closed,and the positions occurred for wear were almost the same.The wear sites were at the inlet of long blade,the turning area of hub from axial to radial direction,the entrance area of long pressure surface and the outlet area at the suction surface.With the increase of particle size and concentration,the wear site on the long blade surface will extend from the inlet to the middle part,and the wear site on the suction surface will extend from the outlet to the whole blade.The concentration of particle phase in helix section of diffuser vane is higher than that in diffusion section.