多孔介质过滤细颗粒

Experimental research of filtering fine particle by porous media

以活性炭为过滤介质,利用其多孔结构脱除细颗粒,实现低压降除尘工艺。研究活性炭颗粒粒径、滤层厚度以及表观过滤风速等条件对多孔介质过滤细颗粒效果的影响,并通过表面光滑的不锈钢珠进行实验作对比,分析多孔介质过滤细颗粒的机理。结果表明:活性炭颗粒对细颗粒的过滤效率明显高于表面光滑的不锈钢珠。过滤效率随活性炭颗粒粒径和表观过滤风速的减小而增加,当粒径从1.5 mm降至0.45 mm时,平均过滤率从53.17%升至80.34%,当表观风速从26.54 cm·s^(-1)降到1.66 cm·s^(-1)时,平均过滤率从41.89%升至75.24%。过滤效率随滤层厚度的增加明显增加,当层厚从60 mm增加到140 mm时,过滤效率从47.62%增大到70.78%。不同实验条件下,过滤压降都没有随时间有明显变化,细颗粒没有在活性炭颗粒表层形成粉尘层。活性炭颗粒床主要是依靠细颗粒扩散、惯性碰撞和拦截效应沉积在活性炭多孔结构内,从而脱除细颗粒。

An activated carbon（ AC） bed was used to filter dust under conditions of low pressure-drop,thereby utilizing the advantage of porous structures. Grain size,bed thickness and superficial velocity were investigated for their effects on particulate removal efficiency. The filtration mechanisms were discussed by the contrast test of smooth stainless steel beads. The AC bed achieved significantly higher removal efficiency than the smooth,stainless steel beads. In the AC system,filtration efficiency increased with decreasing AC size and superficial velocity,and with increasing bed thickness. In experimental scenarios,AC size was decreased from1. 5 mm to 0. 45 mm,superficial velocity was reduced from 26. 54 cm·s-1to 1. 66 cm·s-1and the filter medium increased from 60 mm to 140 mm： consequently,average filtration efficiency increased from 53. 17% to80. 34%,from 41. 89% to 75. 24% and from 47. 62% to 70. 78%,respectively. Under differing test conditions,fine particulates did not form dust cake on the surface of the granular ACs,which contributed to a non-significant change in pressure-drop with time. The AC bed was able to remove fine particles via the filtration mechanisms of diffusion,inertial impaction,and interception.