摘 要

随着我国经济不断的进步，工业、商业的用电量也不断提升，电力工业中的烟气排放也越来越大，其中的NO_x对环境造成了严重的污染。虽然玻璃行业中烟气的排放比火力电厂的少，但是脱硝项目仍然需要关注。

本课题主要是运用数值模拟的方法，通过Gambit软件建立三种不同形状的催化剂孔道模型。利用Fluent软件对三种形状的孔结构进行流场的数值模拟，比较烟气在这三种形状的催化剂内部截面速度的分布和流经催化剂后压力变化，然后分析孔形状对积灰及压降的影响。再通过气固两相流数值模拟，得到飞灰颗粒的运动轨迹和浓度分布，最后分析在不同烟气条件下该选取何种结构的催化剂。

课题中，我们模拟了圆孔催化剂、方孔催化剂以及三角孔催化剂这三种模型，并模拟了烟气在反应器内部的速度流场以及在通过催化剂层时的速度场，最后还模拟了反应器内部的压力变化。得出了烟气在圆孔结构的催化剂中速度变化较小，流速最快，因此积灰的程度最小，但是磨损最大，而烟气在三角孔和方孔结构的催化剂中的流速变化较大，流速较慢，所以这两种催化剂较容易积灰，但是磨损比较小。在进行飞灰颗粒模拟之后，发现在一些催化剂棱角处飞灰颗粒的浓度可能会比较高，也许会引起粉尘的堆积，导致孔道的堵塞，因此在安装反应器的时候，应该在每层催化剂层安装吹灰器。

最后我们分析认为在处理粉灰含量较高的烟气时，应该选择圆孔结构的催化剂；在处理流速较高、空速较大的烟气时，可以选择三角孔结构的或者方孔结构的，而且都应该安装吹灰器。

关键词：SCR、催化剂孔结构、数值模拟、流场模拟、飞灰颗粒

Abstract

With the continuous progress of China's economic, industrial, commercial electricity consumption is rising, flue gas emissions in the electric power industry is also growing, which NO_x caused serious pollution to the environment. Although the glass industry in the flue gas of thermal power plant emissions than less, but the denitration project still needs to concern.

This topic is mainly using numerical simulation method, through the gambit software to establish three different shapes of the catalyst pore model, using FLUENT software to three types of pore structure flow field numerical simulation，the velocity distribution of the flue gas in the three types of catalysts and the pressure change after passing through the catalyst are compared and then the influence of hole shape on ash deposition and pressure drop is analyzed. Then the trajectory and concentration distribution of fly ash particles are obtained by numerical simulation of gas-solid two-phase flow, finally, the structure of the catalyst under different flue gas conditions should be selected.

In the subject, we simulated three models, such as round hole catalyst, square hole catalyst and triangular hole catalyst,and then the velocity field in the reactor and the velocity field through the catalyst layer are simulated. Finally, the pressure changes in the reactor are simulated. We arrive at a conclusion that the velocity of flue gas is smaller in the catalyst with round hole structure, the flow rate is the fastest,so, the degree of ash deposition is minimal,but the amount of wear is the greatest. However the velocity of flue gas in the catalyst with triangular hole and square hole structure varies greatly, the flow rate is slow, so these two kinds of catalysts is easy to fouling, but the wear is relatively small. After we have carried out the coal ash particle simulation, we found that the concentration of coal ash particles may be higher in some catalyst edges and corners, maybe it will cause dust accumulation, this leads to blockage of the channel. Therefore, when the reactor is installed, the soot blower shall be installed in the catalyst.

Finally, it is considered that the catalyst with round hole structure should be selected when the flue gas with high ash content is treated, he triangular hole structure or the square hole structure can be selected when the flue gas with higher flow velocity and larger GHSV is disposed and they should all be fitted with soot blower.

Key Words:SCR; catalyst pore structure; numerical simulation; flow field simulation；coal ash

目 录

第一章 绪论 1

1.1我国烟气脱硝背景及现状 1

1.2 烟气脱硝技术的发展 2

1.2.1 国内外的一些脱硝工艺 2

1.2.2 SCR技术在国内外的应用现状 3

1.3 SCR技术的核心 4

1.3.1 SCR催化剂的组成成分 4

1.3.2 SCR催化剂的选型 4

1.3.3 SCR催化剂的失活 5

1.4 数值模拟 6

1.4.1 数值模拟软件 6

1.4.2 数值模拟方法的优点 6

1.5 课题研究内容、预期目标 7

第二章 实验模拟 8

2.1 孔结构的流场数值模拟建模 8

2.1.1 建立催化剂的几何模型 8

2.1.2 简化SCR反应器的模型 9

2.1.3 划分催化剂截面网格 9

2.1.4 确立边界条件 11

2.2 飞灰颗粒对催化剂性能的影响模拟 12

2.2.1 确定模拟使用的模型 12

2.2.2 飞灰颗粒数值模拟参数设定 13

2.3 模拟结果分析 13

2.3.1 反应器的流场分析 13

2.3.2 速度场测量 15

2.3.3 压力场的模拟 20

2.3.4 飞灰颗粒的模拟 23

第三章 实验结论 25

参考文献 26

致谢 28

第一章 绪论

1.1我国烟气脱硝背景及现状

从21世纪我国经济崛起以来,我国对能源的消耗日渐增大,由能源消耗引起的环境污染问题越来越受到人们的关注；在我国，主要通过燃煤手段进行发电，提高电能，但是在燃煤的过程中会产生NO、NO₂以及N₂O等氮氧化物，这些氮氧化物会对环境以及人体产生危害。

N0对血红蛋白具有非常强的亲和力，是氧气的数十万倍。一旦NO进入血液中，就会把氧气从血红蛋白中驱赶出来，并与血红蛋白牢固地结合在一起。长时间的在浓度为1~1.5mg/L的NO环境中生活会引起支气管炎和肺气肿等病变。NO被排放到大气中时，会促使O₃的产生，从而导致光化学烟雾的形成，光化学烟雾会对人体产生危害。在大气中，NO会缓慢的氧化成NO₂,NO₂是硝酸和亚硝酸的前驱体,会形成酸雨,生成的酸雨和光化学烟雾会导致森林大面积枯萎、腐蚀建筑和设备等危害^[1]。面对氮氧化物带来的危害，各个国家都采取了相应的手段处理；对于我国现有的情况，我国有72.3%的氮氧化物来自燃煤，若要减轻氮氧化物带来的危害，对燃煤电厂的脱硝是必不可少的。