A New Calculation Method of the Axial and Radial Velocity and Grade—Efficiency for High—Efficiency Cyclones

At present in China, the cyclones are widely used in the dust removal ventilation system of boilers, industry furnaces or pits etc., because of their simple structure, long life and cost efficiency. In order to improve efficiency of the cyclones, new theoretical calculation method is very important. In this paper, the concept of down-flow quantity is introduced and new formula is deducted based on Kilven law and the work has done by Zhao Weizhong^[1]. The formula is not only of advantage theoretically but also fit with experimental results quite well. On the basis, the effect of three-dimensional velocity distribution in the flow field within cyclones and other parameters on the grade-efficiency calculation are analyzed and a new equation for grade-efficiency estimation is introduced. The calculating accuracy of the equation is better than the others theoretically and experimentally.     

防返混锥对旋风除尘器内二次流的抑制效果研究

旋风除尘器下部灰斗内存在的二次流会引起被捕集颗粒重新进入气流,进而导致旋风除尘器除尘效率下降。为有效抑制灰斗内二次流,采用内置防返混锥的手段,对不同防返混锥几何尺寸与安装位置的旋风除尘器进行两相流数值模拟。结果表明,内置防返混锥减少了灰斗内流场的切向、轴向速度及湍流强度,对旋风除尘器灰斗内二次流所引起的颗粒返混现象有显著的抑制作用。模拟结果推荐防返混锥最佳几何尺寸的顶角角度为80°,最佳安装位置为底面与锥口的垂直距离0.375B≤Bs≤0.5B。在入口速度为12 m/s时,与原结构相比,总除尘效率提高11.50%,压降增加8.29%。     

高效旋风器分级效率理论计算的新方法

本文根据旋风器内气流的轴向速度分布规律确定尘粒在旋风器内的平均停留时间;考虑筒体和锥体边界层内粒子的捕集分离,建立旋风器分级效率的数学模型,并推出了旋风器分级效率的理论计算公式.新理论公式考虑了旋风器内气体的三维速度分布规律及旋风器各主要结构参数和运行参数的影响,从捕集机理的角度看,新理论公式优于已有的分级效率公式;通过实验验证,新理论公式的计算值与实测值符合得较好.     

A New Calculation Method of the Axial and Radial Velocity and Grade──Efficiency for High──Efficiency Cyclones

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高效旋风分离器分级效率理论计算的新方法

研究了旋风分离器内流场的三维速度分布和各主要结构参数对分级效率计算的影响,推出了新的旋风分离器分级效率计算公式。不论从分离机理方面看,还是通过实验验证,新理论公式均优于国内外已有的理论计算公式。