ABSTRACT

A wide-angle diffuser installed at the entrance of an electrostatic precipitator (ESP) causes a non-uniform flow distribution due to the boundary layer separation. Because a non-uniform flow pattern decreases the particulate matter control efficiency of an ESP, it is important to maintain a uniform flow distribution. The objective of this study is therefore to understand flow distribution with the conditions of perforated plates placed in the diffuser and then to design an ESP to obtain uniform flow. Discharge coefficients were determined varying the porosity, thickness, and number of holes of the perforated plate inside the lab-scale duct system. The test results suggest that the perforated plate with a porosity of 50%, a thickness of 5 mm, and 0.104 hole/m² perforated plate is most acceptable. This perforated plate was placed in the diffuser of the lab-scale ESP system. Velocity profiles in the body of the ESP were obtained depending on the number and arrangement of perforated plates in the diffuser. One perforated plate placed in the diffuser did not improve the flow distribution. Although more uniform flow distribution was found with two perforated plates, stalled flow regions still existed at the top and bottom of the ESP body. When three perforated plates were placed in the diffuser, the 2nd and 3rd perforated plates were important to obtain uniform flow distribution. When the 2nd and 3rd perforated plates were placed at the inlet side and outlet of the diffuser, respectively, the most uniform flow distribution was obtained in the body of the ESP.

Implications: In order to determine the optimal perforated plate for Electrostatic Precipitator (ESP), we investigated the discharge coefficient depending on the structure of the perforated plate in a square duct. We measured the velocity distribution in a laboratory ESP with perforated plates and found the effect of the number and arrangement of perforated plates on the flow distribution in the collection region. Based on the test results, we found the configuration of perforated plates for uniform flow distribution in the body of the ESP.

摘要

由于边界层分离，安装在静电除尘器 (ESP) 入口处的广角扩散器会导致流量分布不均匀。因为不均匀的流型会降低 ESP 的颗粒物控制效率，所以保持均匀的流量分布很重要。因此，本研究的目的是了解扩散器中多孔板条件下的流量分布，然后设计 ESP 以获得均匀的流量。流量系数是通过改变实验室规模管道系统内多孔板的孔隙率、厚度和孔数来确定的。试验结果表明孔隙率为50%、厚度为5 mm、0.104孔/m ²的穿孔板穿孔板是最可接受的。这个多孔板被放置在实验室规模的 ESP 系统的扩散器中。ESP 主体中的速度分布取决于扩散器中穿孔板的数量和排列。放置在扩散器中的一个多孔板并没有改善流量分布。尽管使用两个多孔板发现了更均匀的流动分布，但在 ESP 主体的顶部和底部仍然存在滞流区。当在扩散器中放置三个多孔板时，第 2 个和第 3 个多孔板对于获得均匀的流量分布很重要。当第 2 和第 3 孔板分别放置在扩散器的入口侧和出口侧时，ESP 体内的流量分布最均匀。

启示: 为了确定静电除尘器 (ESP) 的最佳穿孔板，我们研究了取决于方形管道中穿孔板结构的排放系数。我们在带有多孔板的实验室 ESP 中测量了速度分布，并发现了多孔板的数量和排列对收集区域中的流动分布的影响。根据测试结果，我们发现了多孔板的配置，以在 ESP 的主体中实现均匀的流量分布。