毕 业 设 计(论文)

系 别 动力工程系

专业班级 环境工程 班

学生姓名

指导教师

二○一三年六月 题 目 燃煤锅炉燃烧过程流场及温度场数值模拟 华北电力大学科技学院本科毕业设计（论文）

I

摘 要

数值模拟是以电子计算机为手段，通过数值计算和图像显示的方法，达到对工程问题和物理问题乃至自然界各类问题研究的目的。课题涉及到三维燃烧过程，并带有两相流。综合考虑，我选择了目前应用比较广泛的FLUENT软件作为数值模拟的工具。

本文对锅炉炉膛计算域通过GAMBIT软件构建三维框架结构，从而对其进行网格划分，确定合适的数学物理模型，设置边界条件，选用适当的变量和参数，对炉膛燃烧进行三维数值模拟，得出炉膛内流场与温度场分布。最后经过简单的处理，将模拟结果以图片或图表的形式进行直观的展示。通过对模拟结果的观察分析得出合理的结论，并分析不足之处。改变燃尽风风速大小，选择30m/s、40m/s、49m/s及60m/s三种燃尽风速，研究燃尽风风速对炉内混合特性和炉内温度场的影响。结果表明:燃尽风口风速增大时，炉内气流的旋转强度随之增强，燃尽风的穿透程度随之加强，相对容易穿透到炉膛中心，从而使得烟气与煤粉的混合加剧，有利于增加煤炭燃烧的效率；在一定条件下，随着燃尽风速的增加，炉膛中心的高温区域面积增加，而且相对集中；随着燃尽风速的增加，锅炉烟气出口的温度降低；燃尽风风速为49m/s时炉内燃烧状况最佳。

关键词：流场；温度场；数值模拟；燃尽风

华北电力大学科技学院本科毕业设计（论文）

II

NUMERICAL SIMULATION ON FLOW

FIELD AND TEMPERATURE FIELD OF

THE COMBUSTION PROCESS IN THE

FIRED PULVERIZED-COAL BOILER

Abstract

Numerical simulation uses electronic computers as the means. To achieve the purpose of

engineering problems and physical problems as well as the nature of various problems, it uses

the method of the numerical calculation and image shows. The topic relates to the

three-dimensional combustion process and the two-phase flow. Considered, I chose the FLUENT

as the tool for numerical simulation.

In this paper, establishing the three dimensional frame construction with GAMBIT, carrying

on the grid division, then selecting the appropriate model of mathematics and physics and the

suitable parameter and the variable, setting up the boundary condition, making three-dimensional

numerical simulation of furnace combustion, receiving the distributions of flow field and

temperature field in the furnace. After simple processing, we can show the result by making the

pictures or diagrams. Making a conclusion from the results and finding out the inadequacies of

the results. Changing the size of velocity of over fired air，choose 30,40,49 and 60 meters per

second，then discuss what will happen about mixing characteristics of the furnace and

temperature field.Study results indicate that As burnout air speed increases, the rotation of the

furnace air flow intensity increases, and the degree of penetration strength increases, it’s easy to

penetrate into the center of the furnace relatively, so that the mixture of flue gas and coal

increases, the increasing efficiency of coal combustion is also in favor.Under certain conditions,

as the velocity of over fired air increases,the temperature of furnace center area increases, more

concentrated;and the temperature of the boiler flue gas outlet slso reduced；the best overfire air

velocity for optimum combustion furnace is 49 meters per second.

Keywords:Flow Field;Temperature Field;Numerical Simulation;Over Fired Air华北电力大学科技学院本科毕业设计（论文）

目 录

摘要 ............................................................................................... 错误!未定义书签。

ABSTRACT ......................................................... 错误!未定义书签。错误!未定义书签。

1绪论 ............................................................................................................................ 1

1.1课题背景 ................................................................................................................. 1

1.2燃烧过程数值模拟发展概况 ................................................................................. 1

1.3燃煤锅炉燃烧过程的数值模拟研究现状 ............................................................. 1

1.4FLUENT软件 ............................................................................................................ 2

1.4.1简介 ...................................................................................................................... 2

1.4.2优点 ...................................................................................................................... 2

1.4.3局限性 .................................................................................................................. 2

1.5燃煤锅炉燃烧过程流场及温度场数值模拟简介 ................................................. 3

1.5.1气相湍流流动模型 .............................................................................................. 3

1.5.2气固两相流动模型 .............................................................................................. 3

1.5.3辐射换热模型 ...................................................................................................... 3

1.5.4弥散相模型 .......................................................................................................... 5

1.5.5煤粉燃烧模型 ...................................................................................................... 6

1.6本文主要研究内容 ................................................................................................. 6

2模型建立及计算 ........................................................................................................ 8

2.1燃煤锅炉原理 ......................................................................................................... 8

2.1.1电厂锅炉工作原理 .............................................................................................. 8

2.1.2电厂锅炉发展概况 .............................................................................................. 8

2.2燃煤锅炉特性 ......................................................................................................... 8

2.2.1锅炉型号 .............................................................................................................. 8

2.2.2锅炉燃煤煤质分析 .............................................................................................. 9

2.3炉膛模型 ............................................................................................................... 10

2.3.1炉膛整体模型的选择 ........................................................................................ 10

2.3.2炉膛燃烧器及燃尽风口的分布 ........................................................................ 10

2.3.3炉膛模型的网格化 ............................................................................................ 11

2.4数学模型及计算方法 ........................................................................................... 13

2.4.1数学及几何模型 ................................................................................................ 13

2.4.2计算区域 ............................................................................................................ 13

2.5FLUENT计算步骤 ............................................................................................... 13