燃煤发电厂高温高尘烟气流速静电测量技术研究

高温烟气流速(流量)是实现燃煤电厂选择性催化还原脱硝(SCR)过程优化控制的关键参数之一,提高烟气流量测量的准确性对于提高SCR系统脱硝系统效率和控制NOX排放浓度具有重要意义。针对燃煤电厂烟气管道管径大、截面速度分布不均匀、含尘量高等特点,利用烟道内飞灰颗粒起电,开展了基于静电原理的SCR区高温高尘烟气流速测量方法研究。开发了接触式棒状静电互相关高温烟气流速测量系统,在实验室输送带装置上进行了性能实验评价研究,并对某330 MW燃煤机组锅炉脱硝系统入口烟气流量进行了现场测试。试验结果表明在3.1 m/s^43.6 m/s速度范围内,速度相对误差优于4.8%,重复性误差小于4.1%,验证了静电法烟气流量测量方法的可行性和准确性,并适用于高温高尘烟气恶劣现场环境,为开发新型可靠的高温烟气流速在线测量系统提供了技术基础。

Electrostatic Technique for High-Temperature and High-Dust Flue Gas Velocity Measurement in Coal-Fired Power Plant

High temperature flue gas flow velocity(flow rate)is one of the key parameters for the optimal control of selective catalytic reduction denitrification(SCR)process in coal-fired power plants.The measurement accuracy of flue gas flow rate is of great significance to improve the efficiency of SCR system and to control the emission of NOx pollutant.In view of the characteristics of large cross-section,inhomogeneous velocity distribution and high dust concentration in the flue gas pipeline,the measurement method for high temperature and high dust flue gas velocity in SCR system was presented based on particle charging.A measurement system for high temperature flue gas velocity was developed based on rod electrostatic sensors in combination with cross-correlation method.The performance of the measurement system was evaluated on the laboratory conveyor belt device,and was also tested at the inlet of SCR denitrification system of a 330MW coal-fired boiler.Results showed that the relative error of the measurement system is less than 4.8%and its repeatability is better than 4.1%in the velocity range of 3.1 m/s^43.6 m/s.The system is suitable for the online measurement of flue gas velocity in harsh industrial environments.These results validated that the proposed method for high temperature and high dust flue gas velocity is feasible.