高炉除尘灰细微颗粒物单/双预荷电强化滤袋过滤特性

Unipolar/bipolar pre-charging enhanced the filtration performance of bag filter for fine particulate matter from blast furnace dust

传统袋式除尘器对于细微颗粒物的捕集效率不甚理想,在袋式除尘器入口前增加预荷电装置是一种切实可行的强化其过滤特性的技术手段。设计搭建线板式直流高压预荷电器,研究了不同正/负匹配电压及风速对于双极预荷电高炉除尘灰电凝并行为的影响规律,对比分析了滤袋对未荷电、单极负荷电以及双极荷电高炉除尘灰细微颗粒物(PM_(2.5))的捕集效率与压差特性,得到了不同预荷电方式高炉除尘灰细微颗粒物在滤袋表面沉积的微观形貌结构。结果表明:随着过滤风速(1.5~0.5 m·s^(-1)及匹配负电压(-16~-12 kV)的降低,双极荷电颗粒物凝并效率提高;高炉除尘灰细微颗粒物单/双预荷电均能提高滤袋的过滤效率;对于粒径<0.5μm颗粒,双极预荷电技术对滤袋捕集效率的强化效果好于单极预荷电技术;对粒径为0.5~2.5μm颗粒,单极预荷电技术的强化效果超过了双极预荷电技术;颗粒物单/双预荷电技术还使得滤袋阻力增量值及其增长速率值降低,且单极预荷电技术对于阻力降低效果更为明显。本研究可为利用单/双预荷电技术提升传统袋式除尘器对高炉除尘灰中细微颗粒物的捕集脱除特性提供参考。

The collection efficiency of the conventional bag filter for fine particles is still not ideal. Adding a pre-charging device in front of the inlet of the bag filter is a feasible technical mean to improve its filtration performance. The effects of matching voltage and flow velocity on electric agglomeration of bipolarly charged particles were investigated in this paper. The collection efficiency and pressure drop characteristics of bag filter for uncharged, unipolarly and bipolarly charged particles were compared and studied, and the micromorphology and structure of dust cake was also observed. The results showed that the agglomeration efficiency declined with the decrease of flow velocity(1.5~0.5 m·s^(-1)) and matching voltage(-16~-12 kV). The collection efficiency was significantly improved by the unipolarly and bipolarly charged particle. More specifically, for particles with a particle size smaller than 0.5 μm, the enhancement effect of bipolar pre-charging technology on collection efficiency was higher than that of unipolar pre-charging technology. However, for the particles with a particle size between 0.5 μm and 2.5 μm, the enhancement effect of single-polar precharging technology was higher than that of bipolar precharging technology. The precharging technology also reduced the growth rate and increment of pressure drop of bag filter, and the effect of the single-pole precharging technology on the reduction of resistance was more significant. These findings are very important for the enhanced removal of micron and submicron blast furnace dust by using conventional bag filter.