论文总字数：26804字

摘 要

除雾器作为电厂的关键设备，其除雾性能影响到整个机组的安全高效运行。近年来，国内外众多学者对除雾器除雾性能做了诸多研究。利用FLUENT软件对建立的除雾器模型进行研究，模拟其内部流场，通过对其结构和运行参数的调节来研究效率和压降的影响因素，得出一般性的规律，在此基础上由现有的分析方法提出除雾器的优化设计方案。在以上模型中由于没有考虑二次携带问题，使得模拟结果与实际情况存在一定的偏差。

在本文中，先用上述方法对除雾器模型进行常规研究，壁面类型分别为trap（液滴到达壁面即认为被捕捉）和wallfilm（液滴到达壁面沉积并形成液膜）时各因素对除雾效率的影响。得出一般性规律：一定范围内除雾效率随流体速度的增大而增大，随转折角的减小而增大，随板间距的减小而增大。通过对比分析两种壁面类型的结果，得出模型中采用wallfilm壁面条件更接近实际情况。

由于wallfilm壁面条件存在一定的局限性，本文从液滴与壁面的碰撞机理上找到合适的碰壁模型，对模型进行数值模拟分析，得到了单个液滴碰壁的运动情况。另本文采用响应曲面法设计试验，并基于响应面对结果进行分析，为除雾器的优化设计提出建议。

关键词：数值模拟，碰壁模型，优化设计

Numerical Simulation and Study on Gas - Liquid Separation Process in Demister Channel

ABSTRACT

As a key equipment of the power plant, the defogging performance of demister has an impact on the safe and efficient operation. In recent years, many scholars at home and abroad have done a lot of research on the defogger defrost performance. The defogger model was studied by FLUENT software, and its internal flow field was simulated. By changing the structure parameters and the motion parameters of the defogger to study its influence on the efficiency and pressure drop, the general rule is obtained. Based on the existing analysis method, the optimal design scheme of the defogger is proposed. In the above model, there is a certain deviation between the simulation result and the actual situation because there is no consideration of the secondary carrying problem.

In this paper, the above method is used to study the defogger model, in which the wall types are trap (droplets to reach the wall that is captured) and wallfilm (droplets reach the wall deposition and the formation of liquid film), to study each factor’s impact on defogging effect. It is concluded that the defogging efficiency in some extent increases with the increase of the velocity and increases with the decrease of the turning angle, and increases with the decrease of the plate spacing. By comparing the results of two kinds of wall types, it is concluded that the wallfilm wall condition is closer to the actual situation.

Due to the limitations of wallfilm wall condition, this paper finds a suitable wall model from the collision mechanism of droplet and wall. The numerical simulation of the model is carried out, and the movement of single droplet to collide with the wall is obtained. In this paper, the response surface method is used to design the experiment, and the results are analyzed based on the response face, which provides the guidance for the optimal design of the defogger.

KEY WORDS: numerical simulation，droplet-wall model，optimization design

目 录

第一章 绪论 1

1.1研究背景及意义 1

1.2除雾器研究现状 1

1.3本文研究内容 2

第二章 除雾器通道内除雾特性数值模拟 4

2.1气液分离过程 4

2.2理论模型 4

2.2.1流体流动模型 4

2.2.2离散相（DPM）模型 4

2.3数值模拟 5

2.3.1模型介绍及说明 5

2.3.2 模型计算工况 6

2.3.3数值模拟设置 6

2.4处理结果及分析 7

2.4.1流场分布情况分析 7

2.4.2效率影响因素分析 10

2.4.3壁面条件为wallfilm时结果及分析 13

2.5小结 16

第三章 液滴与壁面碰撞模型研究及模拟 17

3.1壁面模型简介 17

3.2碰壁模型建立 17

3.2.1二次携带机理 17

3.2.2碰壁模型发展 18

3.3碰壁模型数值模拟 20

3.3.1碰壁模型的建立 20

3.3.2碰壁模型数值模拟 21

3.4结果分析 21

3.4.1液滴运动过程描述 21

3.4.2液滴运动过程 22

3.4.3模拟结果分析及验证 24

3.5小结 25

第四章 除雾器的优化设计 26

4.1优化思路 26

4.2优化设计 26

4.2.1响应曲面法介绍 26

4.2.2响应面试验设计 26

4.3优化设计结果分析及讨论 28

4.3.1 回归拟合 28

4.3.2 结果分析 29

4.3.3 结果讨论 31

4.4小结 31

第五章 总结与展望 32

5.1总结 32

5.2展望 32

参考文献 34

致 谢 35

第一章 绪论

1.1研究背景及意义

当今环境污染日趋严重，有毒有害污染物的排放是人类面临的主要问题之一，减少其排放意义重大。烟气脱硫（FGD）技术作为一种工程手段，在电厂的烟气脱硫处理中较为广泛地用来降低的排放量。其中，湿式石灰石-石膏烟气脱硫技术（WFGD）由于广泛而廉价的反应原料和较高的脱硫效率而多被采用。

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