Study On The Impact Of Micro Leaks In Filtration Systems On Particulate Emissions

It is difficult to avoid the problem of loose sealing or even broken filter membrane in the bag filters.Because of unintentional leakage,air flow is direct connected with the outside world,and dust emission is intensified,it can have a great impact on its purification efficiency in a short period of time.This paper discusses the influence of small leakage of leakage area 0%?0.14%on the purification performance of bag filter under the working state and pulse cleaning Ring.In this paper,a small-scale simulation experiment system of pulse clean particulate filtering was constructed.The variation of filtration resistance,PM2.5 and PM10 emission concentration under 3 different wind speeds,under 2 different filter accuracy and leakage area of 0%?0.14%is studied.In order to better obtain the experimental results in the real environment,the particle size ratio of particle emission is analyzed,and the dust emission level of the filtration system under periodic pulse injection is studied.The results are as follows:1.Effect of micro leakage during filtering state:(1)In the same filtration time,with the increase of the leakage area,the filtration resistance of the membrane decreases.When the leakage area is 0.14%,the maximum filtration resistance decreases about 1/4 compared with the non leakage resistance.(2)With the increase of leakage area,the emission concentration of particulate matter increased exponentially.Under the condition of no leakage,the emission concentration increases rapidly at the beginning of filtering,and then gradually drops to near zero value;when the leakage area is less than 0.07%,the particulate matter emission increases slowly with the increase of leakage area,and the concentration is relatively small(less than 600 ?g·L-1);when the leakage area is larger than 0.07%,the particulate matter emission increases rapidly with the leakage area.(3)Leakage area has a significant effect on the particle size ratio of discharged particulate matter.The larger the leakage area is,the particles with a particle size greater than PM2.5 in the discharged particulates more than PM2.5.(4)When there is no leakage,the PM2.5 and PM10 emission concentration of 10 ?m is 18 and 23 times higher than that of 5 ? m respectively;when there is a small leakage,the influence of membrane precision on purification efficiency is significantly reduced.2.Impact of micro leakage during pulse cleaning:(1)For the dust emission in the stable filtration stage,the stable emission concentration level in the presence of leakage is significantly higher than the concentration level in the absence of leakage,and the stable emission concentration change curve with time in the presence of leakage is violently oscillating,not as smooth as the curve without leakage.(2)The stable emission concentration and peak emission concentration can be separated according to the significant difference of their generation time.Therefore,the leakage of the leakage port and the penetration of the filter membrane can be separated relatively effectively.