环栅式动力除尘器分离性能的数值模拟与实验

Numerical simulation and experiments on separation performance of cascade-ring aerodynamic dust separator

【目的】为提高环栅式动力除尘器的分离性能,研究结构参数与工况参数对分离效率和压降的影响,确定最优结构参数和工况参数。【方法】采用数值模拟方法研究结构参数对环栅式动力除尘器分离性能的影响,优化除尘器的结构参数,然后依据优化的结构参数设计除尘器,并搭建分离性能测试实验平台,研究不同工况参数对除尘器的分离效率和压降的影响,确定除尘器的最佳工况参数。【结果】净气流以较高气速通过除尘器后部环缝,颗粒的逃逸发生在最后2级环缝处,最后1级环缝处最高气速为57.88 m/s,一般逃逸颗粒的粒径≤22μm。环栅式动力除尘器优化结构尺寸为:筒体直径为150 mm,环厚度为20 mm,环栅数量为20,前16个环间距为8 mm,后4个环间距为2 mm,环高为5 mm,环错位为1 mm。环栅式动力除尘器优化工况参数为:抽气流量分数为20%,气速为15 m/s。【结论】在最优结构参数和工况参数条件下,环栅式动力除尘器分离效率最高,模拟值更接近实验值。颗粒质量浓度的变化对分离效率影响不大,环栅式动力除尘器适用于分离不同质量浓度的粉尘颗粒。

Objective Cascade-ring aerodynamic dust separator is a type of inertia dust collector that combines many advantages such as stable performance,small space occupation,various installation and arrangement methods and low operation cost.To improve the separation performance of the cascade-ring aerodynamic dust separator,it is necessary to study the effects of structural and operating parameters on the separation efficiency and pressure drop and to determine the optimal structural and operating parameters of the dust separator.Methods Firstly,a simulation was performed by using RNG k-εfor the flow analysis,with the discrete phase models(DPM)employed to calculate the particle trajectories.The influence of ring displacement,ring height,ring numbers and ring interval distance on separation performance was investigated,and these structural parameters of the dust separator were optimised.Secondly,the dust separator was designed based on the optimised structural parameters,and the experimental platform was built.Finally,the effects of velocity,the ratio of exhausted gas to inlet gas and particle concentration on the separation efficiency and pressure drop of the dust separator were investigated to determine the optimal operating parameters of the dust separator.Results and Discussion The gas flow passes through the ring seams at the tail of the dust separator at a high gas velocity,the particles escape at the last two ring seams.The highest air velocity at the last ring seam is 57.88 m/s,with the the escaped particles generally sized below 22μm.Notably,the efficiency of the dust separator decreases as the ring displacement increases,and the ring displacement should be 1 mm.The separation efficiency reaches a maximum value of 77.47%at a ring height of 5 mm,and the ring inclination is about 24°.The pressure drop exhibits an upward trend with increasing ring numbers,reaching a critical drop in the separation efficiency at ring numbers≥30.Therefore,the recommended ring numbers should be 20.The highest separation efficiency of 79.2%is achieved with a ring interval distance of 8 mm.However,to avoid the escape of particles from the ring seams of the last few stages,it is advisable to set the ring interval distance of the last few stages at 2 mm.The optimised structural parameters of the dust separator include a cylinder diameter of 150 mm,ring thickness of 20 mm,20 ring numbers,8 mm ring interval distance of the first 16 rings,2 mm ring interval distance of the last 4 rings,a ring height of 5 mm,and a ring displacement of 1 mm.Considering the operating parameters,the operating cascade-ring aerodynamic dust separator performs best with a ratio of exhausted gas to gas inlet gas set at 20%,and a gas velocity of 15 m/s.Under these conditions,the experimental and simulated pressure drop are recorded at 1.54,1.41 kPa,respectively,and the experimental and simulated separation efficiency are measured at 79.15%and 92.28%,affirming the efficacy of the optimized parameters.Conclusion The effect of structural parameters and operation conditions on the separation performance of cascade-ring aerodynamic dust separators are investigated by numerical simulation and experimental research.The highest separation efficiency is achieved under the optimal structural and operating parameters,with simulated results closely aligning with experiment results.Moreover,the variation of particle concentration has little effect on the separation efficiency,indicating that the cascade-ring aerodynamic dust separator is suitable for separating dust particles of different concentrations.