袋式除尘器气流均匀性及优化的数值模拟研究

发布时间：2018-05-26 10:00

本文选题：袋式除尘器 + 数值模拟　；参考：《南华大学》2015年硕士论文

【摘要】：袋式除尘器具有除尘效率高,适应性强,操作弹性大,使用灵活,结构简单,工作稳定等特点,在冶金、铸造、建材、粮食、机械、轻工等工矿企业的通风除尘系统中得到应用广泛。但是气流组织不合理是袋式除尘器存在的主要问题之一,过滤风速过大,长时间运行下去会持续的对滤袋表面造成冲刷,以及滤袋粉尘负荷过高,频繁清灰导致滤袋的织物松散,使滤袋与袋笼接触位置折叠断裂破损,都会加速滤袋的破损,粉尘会冲刷破损处对角,随着时间推移破损不断扩大,最终造成袋口环状破损,甚至使得袋头和袋身分离,滤袋穿孔会使含尘气体直接排向大气,降低了除尘效率,污染大气环境,增加了空气中可吸入颗粒的浓度,使居民人身健康与城区大气环境品质受到威胁。因此,对袋式除尘器运行期间气流分布不合理的问题亟待解决,本文采用数值模拟的方法并依托于湖南省高校产业化培育项目(12CY011),开展了以下研究:(1)以实物的模型构建袋式除尘器内气体流动的三维模型,结合除尘设备气固分离的基本原理和数值方法,确定进口、滤袋及出口的边界条件,建立以滤袋为边界的气体流动数学模型;对侧进风和下进风式袋式除尘器不同风速下的内部流场,气流分布规律进行了分析,确定了袋式除尘器内速度场和压力场,局部滤袋过滤风速过大的位置,各滤袋流量分配等内容。(2)基于耦合的拉格朗日模型,使用rosin-rammler粒径分布函数,研究了袋式除尘器内气固两相流的扩散运动规律,模拟了袋室内颗粒的运动轨迹,各滤袋处理含尘气体负荷,浓度分布的分布情况。(3)针对下进风气流分布和浓度场分布不均匀,提出优化的措施,模拟了在入口处设置挡板和钝体后,不同风速下袋式除尘器内的气流组织情况,颗粒在袋室内的运动规律,为除尘器的结构优化方向提供参考。(4)对侧进风、下进风及优化后的下进风方式进行了比较,对气流分布规律,滤袋容易破袋的位置,浓度分布及设备阻力进行了分析,比较了各种方式下的优缺点,指出改进后的下进风式除尘器气流组织最合理,对滤袋磨损最小,综合效果最佳。
[Abstract]:Bag dust collector with high dust removal efficiency, strong adaptability, flexible operation, simple structure, stable work, in metallurgy, casting, building materials, grain, machinery, The ventilation and dust removal system of light industry and mining enterprises is widely used. However, unreasonable airflow organization is one of the main problems of bag dust collector. If the filter wind speed is too large, it will continuously scour the filter bag surface if it runs for a long time, and the dust load of the filter bag will be too high. Frequent ash removal results in loose fabric of the filter bag, which makes the filter bag break and break in contact with the bag cage, which will accelerate the damage of the filter bag, and the dust will wash away the diagonal angle of the damaged place, and the damage will expand with time, resulting in the annular breakage of the bag mouth. Even when the bag head is separated from the bag body, the perforation of the filter bag will directly drain the dust-containing gas into the atmosphere, reduce the dust removal efficiency, pollute the atmospheric environment, and increase the concentration of respirable particles in the air. The health of residents and the quality of urban air environment are threatened. Therefore, the unreasonable distribution of airflow during the operation of the bag dust collector should be solved urgently. In this paper, a numerical simulation method is used to construct a three-dimensional model of gas flow in a bag precipitator, which is based on the industrialization cultivation project 12CY0111 of Hunan Province, and the following research is carried out. Combined with the basic principle and numerical method of gas-solid separation of dust removal equipment, the boundary conditions of inlet, filter bag and outlet are determined, and the mathematical model of gas flow with filter bag as the boundary is established. The internal flow field and the distribution law of air flow in the bag filter with different wind speeds are analyzed, and the velocity field and pressure field in the bag filter are determined, and the position of the local filter bag filter wind speed is too large. Based on the coupled Lagrangian model and rosin-rammler particle size distribution function, the diffusion motion of gas-solid two-phase flow in bag dust collector is studied, and the movement trajectory of particles in the bag is simulated. In view of the uneven distribution of inlet air flow and concentration field, the optimized measures are put forward to simulate the installation of baffles and blunt bodies at the entrance. The distribution of airflow in bag dust collector under different wind speed and the movement rule of particles in bag room are compared, which provides a reference for optimizing direction of structure of dust collector. In this paper, the distribution of airflow, the location, concentration distribution and resistance of the filter bag are analyzed, and the advantages and disadvantages of various methods are compared. It is pointed out that the air distribution of the improved down-air dust collector is the most reasonable, and the wear of the filter bag is the least. The comprehensive effect is the best.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X701.2

【共引文献】