为指导袋式除尘器滤袋由圆筒变为褶皱结构的升级改造设计,采用计算流体力学数值模拟方法对比分析了滤袋长度和结构、理论过滤风速、渗透率对圆筒滤袋和褶皱滤袋纵向过滤风速均匀性的影响,并分析了过滤风量不变时,将圆筒滤袋改造为不同长度褶皱滤袋后过滤风速分布的变化.结果表明,褶皱滤袋较同长度、同外径、同过滤风量圆筒滤袋过滤风速分布不均匀,且随袋长增加均匀性变差,袋长超过4 m的褶皱滤袋上部1/4处过滤风速迅速增大,甚至超过圆筒滤袋;随理论过滤风速的增加,褶皱滤袋下部过滤风速变化不大,但上部1/4处过滤风速迅速增大,故褶皱滤袋理论过滤风速的设置不宜过高,以＜0.63 m/min为宜;随着滤袋渗透率的减小,滤袋整体过滤风速分布不均匀,褶皱滤袋差异性更加显著,因此其清灰阻力不宜过高.将L=8 m的圆筒滤袋改造为L=5～8 m的褶皱滤袋后,滤袋越长,理论过滤风速越小,过滤风速均匀性越差,综合考虑过滤风速及其均匀性两方面因素,建议将袋长设计为7 m.
NUMERICAL SIMULATION ANALYSIS OF FILTRATION VELOCITY DISTRIBUTION OF CYLINDRICAL AND PLEATED FILTER BAGS
To guide the upgrading design of bag filter's bag from cylindrical to pleated structure,the effects of filter bag length and structure,theoretical face velocity,and permeability on the vertical filtration velocity distribution uniformity of cylindrical and pleated filter bag were compared and analyzed by computational fluid dynamics numerical simulation method.The change of face velocity distribution after changing the cylindrical filter bag into a pleated filter bag with different lengths was analyzed under the condition of constant filter air volume.The results showed that along the length direction of the filter bag,the face velocity distribution of the pleated filter bag was more uneven than that of the same length,the same outer diameter and the same filter air volume cylindrical filter bag,and the uniformity became worse with the increase of the bag length.The face velocity at the upper 1/4 of the pleated filter bag with a bag length of more than 4 m increased rapidly and even exceeded the cylindrical filter bag.With the increase of the theoretical face velocity,the face velocity at the lower part of the pleated filter bag did not change much,but at the upper 1/4,velocity increased rapidly.Therefore,the setting of the theoretical face velocity of the pleated filter bag should not be too high.Under the conditions of this study,it was advisable to be 0.63 m/min below.With the decrease in permeability of the filter bag,the face velocity distribution was more uneven,and the difference along the pleated filter bag was more significant,so the cleaning pressure drop should not be too high.After transforming the cylindrical filter bag with L=8 m into the pleated filter bag with L=5 to 8 m,the longer the filter bag,the smaller the theoretical face velocity,but the worse the uniformity of the face velocity.Considering these two factors,face velocity and uniformity,it was recommended to be 7 m under the conditions of this study.
face velocityfilter bag lengthpleated filter bagbag filternumerical simulation
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