回流式皮带机静电除尘罩除尘效率的试验

为了有效控制皮带机转运点的粉尘污染,研发了一种回流式皮带机静电除尘罩。该除尘罩主要由Ω形极板罩、高压放电极和回流风机等构成,通过调节回流风机的流量,可以使微细粉尘在循环流动中被反复净化。因而研究回流率对除尘效率的影响规律是重要的。试验直接采用实物静电除尘罩,试验粉尘采用中位径为4.496μm的石灰粉,用滤膜称重法测粉尘质量浓度,通过回流风机控制回流量大小进行效率对比试验。结果表明:在给定的外加电压下,回流式皮带机静电除尘罩的除尘效率随回流率增加而提高,当电压大于50 kV,回流率ζ=30%时,除尘效率超过90%,但当回流率ζ30%,除尘效率增加趋缓。当初始粉尘质量浓度为102.34 mg/m~3时,在试验条件下改变回流率和电场强度,排放质量浓度最低可达到5.16 mg/m~3,可实现超净排放。

Experimental investigation for the collection efficiency of the electrostatic hood with the circulation flow of the belt conveyor

The paper is engaged in an experimental investigation for the collection efficiency of the electrostatic hood with the circulation flow of the belt conveyor.In this paper,an electrostatic hood with the circulation flow for the belt conveyor has been proposed so as to be able to control the dust emission from the transshipment point more efficiently.In this case,the fine particles can be expected to be controlled in the circulation flow,which is mainly composed of the omega-shaped polar plate,high voltage discharge electrode and the circulation fan.Therefore,it is of great need to investigate the variation of the collection efficiency with the reflux ratio influenced by the circulation fan in the electrostatic hood experimentally.In this experiment an electrostatic hood is used as the same as the real one in the practice with the lime powder with the 4.496 μm median diameter employed for the test.The dust concentration is measured by the filter-paper sampling method whereas changing the flow rate of the circulation fan can help to determine the dust collection efficiency at the different reflux ratios.The experimental results show that the collection efficiency can be made higher with the increase of the reflux ratio under a given voltage.For example,when the voltage is greater than 50kV with the reflux ratio ξ going up to 30％,the dust collection efficiency can be expected to reach over 90％.Nevertheless,when the reflux ratio ξ has exceeded 30％,there may not be taking place obvious change with the collection efficiency.On the contrarily,when the initial concentration is 102.34 mg/m3,the emission concentration would be only 5.16 mg/m3 under the experimental conditions.It can thus be predicted that the collection efficiency in the industrial application may likely be promoted somewhat higher than the aforementioned experimental results because the dust volume used in the test remains relatively small.Therefore,in comparison with the common dust removal system in the transportation point,the application of the electrostatic hood may be advantageous in a number of ways,such as higher collection efficiency,simpler structure,and lower cost.