带液滴辅助捕集结构的折板除雾器性能数值模拟及优化

发布时间：2018-04-27 06:04

本文选题：折板除雾器 + 液滴辅助捕集结构　；参考：《天津大学》2015年硕士论文

【摘要】：在过程工业中气相中夹带的液滴如果进入后续工艺会影响工艺的稳定性,进入后续设备可能造成设备的损坏,排放到大气环境中则可能污染环境或造成物料损失。如何经济高效的解决这一问题,具有重要意义。折板除雾器因其结构简单、压降低、不易堵塞、易于冲洗等优点得到了广泛的应用。但是传统的折板除雾器只适用于截留颗粒粒径大于10μm的液滴,本文拟在结构上进行改进,拓展其应用范围,提高截留效率。随着计算机技术的飞速发展,数值模拟方法在折板除雾器的开发过程中应用效果得到认可。本文采用计算流体力学软件FLUENT6.3对带液滴辅助捕集结构的折板除雾器内的流场及液滴轨迹进行数值模拟及结构优化,以期为工业设计提供指导。采用欧拉-拉格朗日方法模拟两相流动,对于气相流场采用SST k-ω湍流模型,离散相采用DPM,不考虑气液两相的耦合,模拟除雾器内部气液两相流动状态。数值模拟结果经过文献数据验证,确定该模拟方法的可靠性,然后研究了2~5m/s进口气速下,引入液滴辅助捕集结构前后的折板除雾器内部流场和液滴轨迹的变化情况,对比了分离效率和进出口总压降两个性能指标。结果表明可见不同进口气速条件下,气液两相流场在液滴辅助捕集结构处产生了涡旋,增大了气流湍动能,同时高速区明显增多,更有利于液滴的捕集,但同时进出口压降有所上升。分析发现液滴辅助捕集结构高度是影响流场、分离效率和进出口压降的主要因素。系统分析了该结构参数对通道内的最大气速值、高速区和低速区面积等参数流场变化参数,以及液滴分离效率和进出口压降等性能参数的影响,获得优化的结构参数。液滴辅助捕集结构高度选取为通道宽度的35%、48%和60%,对于三级结构的除雾器,总共有27种的高度组合方式。结果表明在2~5m/s的进口气速下,建议将第二级液滴辅助捕集结构高度由通道宽度的48%增加到60%,同时尽量不增加第一级和第三级的液滴辅助捕集结构高度,但是当液滴辅助捕集结构高度由通道宽度的35%增加到48%时,建议改变第一级和第三级液滴辅助捕集结构高度,不改变第二级。最后得到2m/s进口气速下,各级液滴辅助捕集结构高度分别为通道宽度的48%、35%、48%时,综合性能最好;在4m/s的进口气速下,各级液滴辅助捕集结构高度分别均为通道宽度的48%时,综合性能最好。
[Abstract]:The stability of the process will be affected if the droplets entrainment in the gas phase in the process industry is entered into the follow-up process, the equipment may be damaged by entering the follow-up equipment, and the discharge into the atmospheric environment may pollute the environment or cause material loss. How to solve this problem economically and efficiently is of great significance. Folding plate mist remover has been widely used because of its simple structure, low pressure, easy clogging and easy washing. However, the traditional folding plate mist remover is only suitable for retaining droplets with particle size larger than 10 渭 m. In this paper, the structure of the droplet is improved to expand its application range and improve the retention efficiency. With the rapid development of computer technology, the application effect of numerical simulation method in the development of folding plate mist remover has been recognized. In this paper, the flow field and droplet trajectory in the folding plate demister with droplet assisted capture structure are numerically simulated and optimized by the computational fluid dynamics software FLUENT6.3, in order to provide guidance for industrial design. Euler-Lagrangian method is used to simulate two-phase flow, SST k- 蠅 turbulence model is used for gas-phase flow field, and SST is used for discrete phase. The gas-liquid two-phase flow state is simulated without considering the coupling of gas-liquid two-phase. The numerical simulation results are verified by the literature data, and the reliability of the simulation method is determined. Then, the variation of the flow field and droplet trajectory in the fold-plate mist eliminator before and after the introduction of the droplet assisted capture structure under the inlet gas velocity of 2~5m/s is studied. The separation efficiency and the total pressure drop are compared. The results show that under different inlet gas velocities, the gas-liquid two-phase flow field produces vortex at the structure of droplet assisted capture, which increases the turbulent kinetic energy of the airflow, and increases obviously in the high-speed region, which is more favorable to the trapping of droplets. But at the same time import and export pressure drop has increased. It is found that the height of droplet assisted capture structure is the main factor affecting the flow field, separation efficiency and inlet and outlet pressure drop. The effects of the structure parameters on the flow field parameters, such as the maximum atmospheric velocity, the area in the high speed and the low speed regions, the separation efficiency of droplets and the pressure drop of the inlet and outlet are systematically analyzed. The optimized structure parameters are obtained. The height of droplet assisted capture structure is 35% of channel width and 60% of channel width. There are 27 kinds of height combination methods for the third order structure fog remover. The results show that under the inlet gas velocity of 2~5m/s, it is suggested that the height of the secondary droplet assisted trap structure should be increased from 48% of the channel width to 60%, while the height of the first and third stage droplet assisted trap structure should not be increased as much as possible. However, when the height of droplet assisted capture structure increases from 35% of the channel width to 48%, it is suggested to change the height of the first and third level of droplet assisted capture structure without changing the second stage. Finally, under the inlet gas velocity of 2m/s, the height of each level of droplet assisted capture structure is 4835 of the channel width, and at 48, the comprehensive performance is the best; under the inlet gas velocity of 4m/s, the height of the various droplet auxiliary capture structure is 48g of the channel width, Comprehensive performance is the best.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051

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