300MW电站回热加热器仿真模型建立及经济运行分析
摘 要
近些年300MW的大型火力发电机组依然在国内电厂占有一定数额，并且还会继续存在甚至加以提高。300MW机组的认识及应用研究并不是很透彻，为了提高电站运行人员的操作水平，保证机组运行的安全性和经济性，电站仿真系统的开发和应用在以后的应用中必不可少，可以对其各种工况和各种工况下的故障进行分析。
本文就是介绍300MW电站回热加热器仿真模型建立及经济运行分析，主要以火电机组回热加热系统中典型且使用广泛的三段式加热器为研究对象，在深入了解加热器的结构和回热加热系统的构成特点，准确掌握加热器传热计算理论与方法及工程分析方法理论的基础上，充分考虑了加热器结构参数和工质物性参数对传热过程的影响以及静态计算公式与动态数学模型间的差别，采用显式欧拉法和灰箱分析模型原理，建立了加热器动态数学模型和回热加热系统经济性分析模型。同时借助仿真手段，通过具体的工作实例，检验了模型的静态计算精度和动态响应特性，并对回热加热系统进行了变工况和各种故障工况的经济性分析，验证了模型的适用性和应用价值。由于目前的培训仿真机的设计、控制系统的设计、机组的优化并不全面， 因此我们有必要开发一套更为精确的机组模型用来满足目前的要求。本文就是主要以研究300MW火电机组中回热加热器的仿真模型建立及经济运行分析就目的，而对实际工况的故障进行正确的研究。
关键词:加热器，回热加热系统，动态数学模型，经济性分析，仿真
I
沈阳工程学院毕业设计(论文)
Abstract
300MW thermal power generating units in recent years is still a large share in the domestic power plant a certain amount, and will continue to exist and even be enhanced. For improving the operators ’skill and insuring the units operate more securely and efficiently, much attention is paid on the effects of power plant simulation systems.
This is the description of Heater 300MW power plant simulation model and analysis of economic operation ,for the main of the three-section feed water heaters，which are widely used in heat recoup system of the large thermal power unit，are taken as the object to be studied in this paper. The dynamic mathematical model of the heater and the economy analysis model of the heater recoup system are built by investigating deeply on the structure，the operating characteristic and the heat transfer theories of the hearts and the heat recoup system. The heater construction parameters and the physical property of the working medium are fully considered in the model. The difference between the static calculation formula and the dynamic model is also considered. The static accuracy and dynamic performance of the mathematic model of the heater are verified by detailed simulation tests and by practical engineering application. The economy of the heat recoup system under different work condition is analyzed with the system economy analysis model.
Key words: heater，heat recoup system，dynamic mathematical model，
Economy analysis，simulation
II
300MW电站回热加热器仿真模型建立及经济运行分析
目 录
摘 要 .............................................................................................................................I Abstract ......................................................................................................................... II 第一章 绪 论 ............................................................................................................. 1
1. 1概述 .................................................................................................................. 1 1. 2选题背景 .......................................................................................................... 2 1.3 数学模型在电站仿真系统中的地位及意义 .................................................. 3 1. 4课题必要性 ...................................................................................................... 4 1. 5本论文完成的工作 .......................................................................................... 5 1.6小结
第二章 加热器的基本理论与技术特性 ...................................................................... 6
2. 1加热器的工作原理 .......................................................................................... 6 2.2 加热器的分类 .................................................................................................. 6
2.2.1按传热方式分类 ................................................................................. 6 2.2.2按结构分类 ......................................................................................... 6 2.2.3按安装布置分类 ................................................................................. 7 2.2.4按压力分类 ......................................................................................... 7
2.3加热器的技术特性 ........................................................................................... 7
2.3.1加热器的传热与加热器的端差 ......................................................... 7
2.4小结 ................................................................................................................... 8 第三 加热器的热力和水力计算 ......................................................................... 9 3.1加热器的传热过程及特点 ............................................................................... 9 3.2影响加热器传热的因素 ................................................................................... 9
3.2.1影响加热器对流换热的因素 ............................................................. 9 3.2.2影响加热器凝结换热的因素 ........................................................... 10
3.3加热器的传热计算 ......................................................................................... 11 3.4加热器的水力计算 ......................................................................................... 20 3.5小结 ................................................................................................................. 20
III
沈阳工程学院毕业设计(论文)
第四章 加热器动态数学模型的建立与验证 ........................................................ 21
4.1 电站设备数学模型概述 ................................................................................ 21 4.2 加热器仿真模型的建立 ................................................................................ 21
4.2.1 建模基础和简化原则 ...................................................................... 21 4.2.2 加热器动态数学模型的描述 .......................................................... 22
4.3 加热器数学模型的验证 ................................................................................ 30 4.4 小结 ................................................................................................................ 30 第五章 回热加热器经济运行的研究 ........................................................................ 31
5.1 电厂经济性分析方法简介 ............................................................................ 31
5.1.1 焓分析法 .......................................................................................... 31 5.1.2 熵分析法 .......................................................................................... 31 5.1.3 火用 分析法 ....................................................................................... 32 5.1.4 三种方法的比较 .............................................................................. 32
5.2 回热加热系统的构成特点 ............................................................................ 33 5.3 必要性 ............................................................................................................ 34 5.4 小结 ................................................................................................................ 34 第六章 回热加热器运行状态的热经济性 ................................................................ 35
6.1 影响回热加热器经济运行的原因 ................................................................ 35
6.1.1 高加切除对机组热经济的影响 ...................................................... 35 6.1.2 给水部分旁路对机组热经济性的影响 .......................................... 36 6.1.3 加热器无水位运行对机组热经济性的影响 .................................. 36 6.1.4 回热加热器的散热对机组热经济性的影响 .................................. 37
6.2 提高回热加热器经济性的有效措施 ............................................................ 38
6.2.1 混合式加热器代替面式高压加热器的研究 .................................. 38 6.2.2 对汽轮机通流部分进行改造 .......................................................... 41
6.3 小结 ................................................................................................................ 42 结 论 ...................................................................................................................... 43 参 考 文 献 ................................................................................................................ 44 致 谢 ...................................................................................................................... 45
IV