双极电袋复合除尘器的增效减阻效应

为提高现有电袋复合除尘器的除尘效率，降低压力损失，改进清灰效果，设计出一种线管式双极电袋复合除尘器，并对其增效减阻作用和单极电袋复合除尘器进行了对比研究。在硅微粉中位径1.74 μm、过滤风速3 m·min-1、入口粉尘浓度2 500 mg·m-3的实验条件下，双极电袋复合除尘器比单极电袋复合除尘器的粉尘透过率、压力损失分别降低25%、27%以上。为分析双极荷电粉尘的静电凝并增效作用，测定了滤料表面沉积粉尘层的粒度分布，发现单极荷电和双极荷电沉积尘的中位径分别为1.83 μm和1.92 μm，表明双极荷电粉尘具有较好的静电凝并作用，所形成的较粗团聚颗粒物不易透过滤料，使除尘效率提高。为阐明双极荷电粉尘的减阻作用，采用自然堆积法测出双极荷电粉尘的堆积密度小于单极荷电粉尘，证明粉尘双极荷电后会在滤料表面形成较蓬松的粉尘层，这将有助于降低压力损失、提高清灰效果。

Efficiency enhancement and drag reduction effects of bipolar electrostatic-bag filter

In order to improve the particle collection, filter cleaning, and pressure drop reduction of the current electrostatic enhancement bag filter, a wire-tube bipolar electrostatic-bag filter was proposed. Then, in comparison with the unipolar electrostatic-bag filter, its efficiency enhancement and drag reduction effects were analyzed when the silicon powder with medium diameter of 1.74 μm was used. The results show that the dust penetration and pressure drop of bipolar electrostatic-bag filter decreased by over 25% and 27% at the filtration velocity of 3 m·min-1 and inlet dust concentration of 2 500 mg·m-3, respectively. To analyze efficiency enhancement effect of the electrostatic agglomeration of the bipolar charged particles, the particle size distribution of the dust layer on the surface of the fabric filter was determined. The medium diameters of unipolar charged and bipolar charged particles were 1.83 μm and 1.92 μm, respectively, which indicated that the latter presented a stronger electrostatic agglomeration effect. Therefore, the particle collection efficiency can be improved due to the difficult penetration of these coarse agglomeration particles through the fabric material. In order to clarify the drag reduction of the bipolar charged particles, the accumulation density of the particles was measured by the natural stacking method. The results showed that the accumulation density of the bipolar charged particles was less than that of the unipolar charged particles. It is proved that if the charged particles are bipolar, a fluffy dust layer can be formed on the surface of the bag. Thus, it is helpful to reduce the pressure drop and improve the filter cleaning effect.