1、 颗粒轨道模型论文:液柱冲击塔内的流场特性研究【中文摘要】液柱冲击塔是一种新的湿法脱硫技术,是在液柱空塔的基础上加装了多孔挡板改造而成的,具备液柱空塔和多孔盘吸收塔的双重优点,是一种理想的脱硫装置。液柱冲击塔具有脱硫效率高,性能可靠,适应性强,工艺过程的自动控制水平高,初投资和运行费用较低等特点,非常适用于工业锅炉的烟气脱硫。目前,对液柱冲击塔的研究刚刚起步,仅进行过实验室规模的试验研究。因此,对大型化液柱冲击塔进行研究对以后的工业化应用有很大的意义。本文以FLUENT 商业软件为平台,对冲击塔的烟气入口倾角、挡板结构、塔内风速等进行优化模拟,以达到最佳的气液均混效果,为了给大型化液柱冲击塔设
2、计提供理论依据。以液柱冲击塔试验台为物理模型,使用欧拉-拉格朗日法对塔内气液两相流动特性进行数值模拟,研究液柱冲击塔的结构参数和操作参数对气液流场的影响,得出最佳结构参数和运行参数,为液柱冲击塔试验台的搭建提供设计依据。试验台运行结构表明,系统脱硫效率高,气液混合效果较好,详见万小涛的硕士学位论文“碱基工业废弃物用于液柱塔湿法脱硫的试验研究” 。研究表明:入口倾角对塔内流动有显著影响,当入口倾角为 15时,塔内的流场与流速分布最佳;多孔挡板对气流有显著的整流效果,综合多孔挡板对流场的整流效果和塔内流速等因素,孔隙率为 0.5 时,多孔挡板对气流整流效果最优;塔内的最佳气流速度为 3m/s。选取
3、某化工厂 220t/h 锅炉湿法脱硫塔为数值计算的物理模型,使用欧拉-拉格朗日法对塔内气液两相流动特性进行模拟,研究塔内流动分布和压力分布,为化工厂脱硫塔的结构和运行参数进行优化,对冲击塔大型化设计提供理论依据。研究表明:浆液的喷淋对塔内流场整流效果显著,气流分布均匀,在多孔挡板区域形成回流区,加强气液间的混合,延长气流在塔内的停留时间;多孔挡板至浆液液面之间的高度对冲击塔内气液两相分布有显著影响,当多孔挡板与浆液液面距离为冲击塔当量直径的 1.56 倍时,塔内气液两相分布较为均匀,效果最佳;在冲击塔入口至多孔挡板之间的湍流区内,随着高度的增加,同一高度层上的压力趋向均匀化且呈层状分布,而在多
4、孔挡板至出口,气流的压力无明显变化。【英文摘要】Liquid column impact tower is a new kind of wet desulphurization technology. Porous baffle is added on the basis of liquid column empty tower for reconstruction. It has the advantages of fluid column empty tower and porous plate absorption tower, and is one kind of ideal desu
5、lphurization installations. Fluid column impact tower has the characteristics of high desulphurization efficiency, reliable performance, strong adaptability, high level of automatic control in technical process, low initial investment and running costs and so on. It is greatly suitable for flue gas
6、desulfurization in industrial boiler. At present, the study on liquid column impact tower is just starting, and it still keeps experimental research in the lab scale. Therefore, it has a great significance to study the large-scale fluid column impact tower for industrial application.Based on the pla
7、tform of business software FLUENT, flue gas entrance angle, baffle structure, wind speed in the tower were simulated and optimized to achieve good gas-liquid mixing effect. This work will provide theoretical basis for the design of large-scale fluid column impact tower.The characteristics of gas-liq
8、uid flow were simulated by using Euler-Lagrange method, and it took fluid column impact tower as the physical model. The impacts of the structure and operating parameters of fluid column impact tower to the gas-liquid flow field were studied. The best structure and operation parameters for fluid col
9、umn shock tower were concluded, which provided the design basis for the construction of the experiment rig. The test running structure of the experiment rig showed that system had high desulfurization efficiency, good gas-liquid mixing effect, please see “Bases for industrial waste fluid column towe
10、r wet desulphurization experiment research” paper for detail. Results showed that:the entrance angle had significant influence on the tower flow. When the entrance was 15, the flow field in the tower and velocity distribution were the best; Porous baffle had significant rectification effect on airfl
11、ow. When the porosity factor was 0.5, the influence was the best by synthesizing factors like the rectification impact of porous baffle on the flow field, flow velocity in the tower and so on. The best airflow velocity for the tower was 3m/s.Selecting a wet desulphurization absorption tower in 220 t
12、/h boilers in a chemical plant as the physical model for numerical calculation, this paper did numerical calculation on gas-liquid two phase flow characteristics inside the tower with Euler-Lagrange method, studying the flow and pressure distribution, which provided theoretical basis for optimizatio
13、n of structural and operation parameters of the desulphurization tower and large-scale design of impingement towers in chemical plants. The research results showed that:slurry spray effected significantly on rectification performance inside the tower with uniform air distribution. Reflux occurred at
14、 the region of the porous baffle, strengthening the mixing between gas and liquid, and prolonging the residence time of the air flow in tower. The height between the porous baffle and the slurry liquid surface exerted significant influence on the gas-liquid two phase distribution inside the impinge
15、tower; when the height was 1.56 times of the equivalent diameter of tower, the gas-liquid two phase distribution in the tower was more uniform, which made better performance. With the height increasing, the pressure tended to be uniform and showed a lamella distribution at the same height level in t
16、he turbulent region between the tower entrance and the porous baffle, while the air pressure showed no significant changes in the region between the porous baffle and the tower exit.【关键词】颗粒轨道模型 液柱喷射 气液两相流 湿法脱硫 数值模拟【英文关键词】particle orbital model Fluid column injection Gas-liquid two phase flow Wet des
17、ulphurization Numerical simulation【目录】液柱冲击塔内的流场特性研究 摘要 8-9 ABSTRACT 9-10 符号表 11-12 1 绪论 12-22 1.1 课题的研究背景 12-13 1.2 脱硫技术综述 13-19 1.2.1 喷淋空塔的工艺和结构 13-14 1.2.2 喷淋-多孔托盘吸收塔的工艺和结构 14-16 1.2.3 液柱塔的工艺和结构 16-18 1.2.4 液柱冲击塔的工艺和结构 18-19 1.3 液柱塔湿法脱硫研究和应用现状 19-21 1.4 课题研究的主要内容 21-22 2 数学模型及计算方法 22-33 2.1 基本控制方程
18、 22 2.2 气相湍流运动模型 22-24 2.3 湍流两相流模型 24-31 2.3.1 离散相轨道计算的数学模型 25-26 2.3.2 射流源类型的设定 26-28 2.3.3 离散相边界条件的设定 28-30 2.3.4 连续相和离散相耦合计算的过程 30-31 2.4 数值计算方法 31 2.5 本章小结 31-33 3 液柱冲击塔结构参数的优化模拟 33-48 3.1 物理模型 33 3.2 基本假设 33-34 3.3 网格划分 34-35 3.4 初始条件和边界条件 35-36 3.4.1入口边界条件 35 3.4.2 出口边界条件 35 3.4.3 壁面边界条件 35-36
19、 3.5 模拟结果与分析 36-47 3.5.1 入口倾角对气相流场的影响 36-39 3.5.2 多孔挡板对气相流场的影响 39-43 3.5.3 塔内风速对塔内流场的影响 43-47 3.6 本章小结 47-48 4 220t/h 湿法液柱冲击塔内部流场数值模拟 48-63 4.1 物理模型 48 4.2 多孔挡板位置的确定 48-49 4.3 网格划分 49 4.4 初始条件和边界条件 49-51 4.4.1 入口边界条件 49-50 4.4.2 出口边界条件 50 4.4.3 壁面边界条件 50-51 4.5 模拟结果与分析 51-62 4.5.1 塔内未喷淋时的流场分析 51-53 4.5.2 塔内有喷淋时的流场分析 53-56 4.5.3 塔内离散相流场分析 56-58 4.5.4 塔内液滴浓度分布 58-60 4.5.5塔内阻力特性分析 60-62 4.6 小结 62-63 5 全文总结和展望 63-65 5.1 全文总结 63-64 5.2 建议 64-65 参考文献 65-70 致谢 70-71 学位论文评阅及答辩情况表 71