高温高尘环境下烟气流量静电感应测量方法研究

论文总字数：22534字

摘 要

烟气流量是燃煤电厂选择性催化还原脱硝过程的关键参数之一，提高烟气流量测量的准确性有利于提高脱硝效率和控制NO_X排放浓度。目前，燃煤电厂广泛采用热导式流量计和多点阵列式差压流量计进行烟气流量测量，但前者只能进行单点测量，后者则存在易堵灰的问题。因此，本文提出了一种基于静电感应原理的烟气流量测量方法，开发了相应的测量系统，并在皮带输送装置上开展了实验研究。

首先，本文对电厂脱硝装置做了简单介绍，阐述了烟气流量测量对提高脱硝效率和经济性的影响性，总结了脱硝过程中烟气流量测量方法研究现状。

然后，利用高温粉尘静电化特性，设计了基于静电传感器的烟气流量测量系统，并详细阐述了该测量系统的软硬件设计。

最后，对烟气流量测量系统在皮带输送装置上开展了实验研究。研究结果表明：在3.25-21.91m/s速度范围内，测量速度的绝对误差在1 m/s左右，相对误差小于10%，波动范围小于0.73m/s，均方差小于0.15m/s，验证了静电法烟气流量测量方法的可行性。

关键词：烟气流量；静电传感器；脱硝；互相关；速度

Abstract

Flue gas flow rate is one of the key parameters in the selective catalytic reduction denitrification system of coal-fired power plants. Accurate measurement of the flue gas flow rate is beneficial to the denitrification efficiency and the control of the NO_x emission concentration. At present, the thermal flowmeter and the multi-point array differential pressure flowmeter are the popular instruments for flue gas flow rate measurement in coal-fired thermal power plants. However, both of these two flowmeters have some advantages. The former only measures the flowrate of single point, while the latter is easy to plug ash in real application. This work proposes a flue gas flow measurement method based on the electrostatic induction principle, which is suitable for the environment of high temperature and high dust. The measurement system based on electrostatic induction is developed and experiments are carried out on a belt conveyer.

First of all, this paper simply introduces the SCR system of the power plant, and illustrates the important effects of the flue gas flow rate measurement on the efficiency and economy of the SCR system. The literature reviews of the existing method on the flue gas flow rate measurement in denitration engineering and electrostatic cross-correlation velocity measurement method are detailed.

According to the electrification of high temperature dust, a measurement system for flue gas flow rate is designed based on electrostatic cross-correlation velocity measurement method. Also, the mechanical design and software design of flue gas flow measurement system are demonstrated.

Finally, the performance evaluation of the flue gas flow measurement system is conducted. Experimental results show that the absolute error of the measurement speed is about 1 m/s when the velocity range is 3.25-21.91m/s, the corresponding relative error is less than 10%. The fluctuation of the measured velocity is less than 0.73 m/s, and the mean square error is less than 0.15 m/s. These results prove that the proposed method is feasible to the velocity measurement.

KEY WORDS: Flue gas flow rate; Electrostatic sensor; SCR system; Cross-correlation; Velocity

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 研究背景 1

1.1.1 氮氧化物选择性催化还原装置 1

1.1.2 不同容量机组对应烟气的流量及温度 2

1.2 研究意义 2

1.3 高温烟气测量研究现状 3

1.3.1 热扩散式流量计 3

1.3.2 差压式流量计 3

1.4 静电法研究现状 4

1.5 本文的主要研究内容 5

第二章 静电互相关测速原理与烟气流量测量系统设计 7

2.1 高温高尘烟气的静电现象 7

2.2 静电互相关测速原理 7

2.3 烟气流量测量系统设计 8

2.3.1 机械设计 8

2.3.2 软件设计 11

2.4 本章小结 14

第三章 静电相关速度测量实验及评价 15

3.1 实验系统搭建 15

3.2 实验结果及误差分析 16

3.3 本章小结 19

第四章 总结与展望 20

4.1 工作总结 20

4.2 展望 20

参考文献 21

第一章 绪论

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