基于调整局部滤袋渗透率的袋式除尘器流量分配方法

Flow distribution method of bag filter based on adjustment of local filter bags permeability

矿山开采、矿石破碎等过程产生大量粉尘,袋式除尘器是去除含尘气流中颗粒物的有效设备。袋式除尘器在运行中存在滤袋过滤风量分配不均问题,现有增加导流板的方式增加了结构的复杂性。为解决中箱体下进风袋式除尘器滤袋质量流量分配不均的问题,提出一种基于调整部分滤袋渗透率的滤袋质量流量均匀分配方法。首先,选择Realizable k-ε双方程模型进行模型袋式除尘器流场的数值模拟,通过数值模拟结果与模型实验的结果对比验证了模拟方法的正确性;然后建立安装160条滤袋的中箱体下进风除尘器几何模型,利用数值模拟方法分析了0.5~1.2 m/min过滤风速下除尘器内流场特征、滤袋的质量流量分配规律和均匀性;最后以1 m/min过滤风速下滤袋质量流量分配不均问题为例,设计了减小质量流量大的出口侧滤袋渗透率的方法;并根据达西公式和滤料阻力计算公式,给出了渗透率与滤料厚度、纤维直径和填充率之间的关系。结果表明:本研究模型下,过滤风速增高会使滤袋质量流量分配更不均匀,除尘器出口侧滤袋的质量流量逐渐增大;将流量偏大区域的8~10列滤袋的渗透率由2.0×10^(−11) m^(2)减小到1.7×10^(−11) m^(2),可使滤袋质量流量分布均方根偏差由0.158降低到0.099,且除尘器初始阻力的增长仅为6.1%,方法具有可行性。在滤料制作过程中可进行滤料渗透率的调整,故通过调整局部滤袋渗透率使滤袋质量流量分布均匀的方法可行。

The process of mining and ore crushing generates a lot of dust.Bag filter is an effective equipment to remove particulate matter from dusty airflow.However,there is a problem of uneven distribution of air volume in the filter bag during operation.The existing way of adding deflectors in bag filters increases the complexity of its structure.In order to solve the problem of uneven distribution of mass flow of middle box lower inlet filter bag,a method of filter bag mass flow even distribution by adjusting selected bags’permeability is proposed.Firstly,realizable k-εequation model is selected to simulate the flow field of model bag filter.Then,the numerical simulation results are compared with model experimental results,which verifies the correctness of the simulation method.After that,a geometric model of filter bag with 160 filter bags installed in the middle box is established.Flow field characteristics,mass flow distribution and uniformity of the filter bag at the face velocity of 0.5~1.2 m/min are analyzed by numerical simulation.Finally,taking the uneven dis-tribution of filter bag mass flow at 1 m/min face velocity as an example problem,a method to reduce the permeability of filter bag at the outlet side with large mass flow is designed.According to the Darcy formula and pressure drop calcula-tion formula of filter material,relationship between permeability and filter material thickness,fiber diameter and filling ra-tio are given.The results show that under this research model,the increase of face velocity will make the mass flow distri-bution of the filter bag more uneven,and the mass flow of the filter bags on the outlet side of the bag filter will gradually increase.Reducing the permeability of 8−10 rows of filter bags in the area with high flow rates from 2.0×10^(−11)m^(2)to 1.7×10^(−11)m^(2)can reduce the root mean square deviation of mass flow distribution of filter bags from 0.158 to 0.099.The increase in the initial pressure drop of filter bag is 6.1%,proving this method is feasible.In the process of making filter material,the permeability of filter material can be adjusted,so it is feasible to make the mass flow distribution of filter bag uniform by adjusting the permeability of filter bag in selected area.