基于静电传感器的煤粉颗粒粒度和质量流量的测量

发布时间：2018-04-27 23:41

本文选题：煤粉 + 气固两相流　；参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：燃煤电厂一次风管道内煤粉颗粒粒度和质量流量的在线测量可以为实时调节制粉系统工作参数提供依据,有助于优化制粉系统工作性能、提高煤粉燃烧效率并降低污染物排放。静电传感器具有测量特性稳定、安装方便、灵敏度高、维护需求低和本质安全等优点,已被应用于工业气固两相流速度、浓度等重要动态参数的测量。本论文首先从理论和实验两方面探索了利用静电传感器测量煤粉颗粒粒度的可行性,利用有限元仿真软件COMSOL分析了单个颗粒的粒度对静电信号强度和频率的影响。然后根据静电法测量原理提出了基于渡越时间的单颗粒粒度测量方法,以及基于颗粒速度变化的多颗粒粒度估测方法。实验选用石英砂和活性炭两种不同性质的材料在74 mm管径的气固两相流装置上进行,测量装置使用2mm和10 mm两种不同轴向宽度的静电电极。最后通过实验研究了含水率对静电法测量颗粒质量流量的影响,并改进了质量流量测量中相关系数的标定方法。有限元仿真结果表明当颗粒带电密度相等时可以通过测量静电信号强度分辨颗粒粒度,当颗粒沿环形静电传感器轴向运动时其所处的径向位置对静电信号频率造成的影响大于颗粒粒度的影响。实验结果表明颗粒粒度会影响静电信号的强度和主频,当气力输送管道内风速一定时颗粒速度随其粒度增大而减小,因此可以通过颗粒速度变化推测颗粒粒度。同等条件下颗粒含水率不同,静电传感器对颗粒质量流量测量结果不同,针对不同含水率条件标定质量流量测量系数可以有效提高测量的准确性。
[Abstract]:On-line measurement of pulverized coal particle size and mass flow in primary air pipe of coal-fired power plant can provide basis for real-time adjusting the working parameters of pulverizing system, help to optimize the working performance of pulverizing system, improve the efficiency of pulverized coal combustion and reduce pollutant emission. Electrostatic sensor has the advantages of stable measurement characteristics, convenient installation, high sensitivity, low maintenance requirement and essential safety. It has been applied to the measurement of important dynamic parameters such as velocity and concentration of gas-solid two-phase flow in industry. In this paper, the feasibility of using electrostatic sensor to measure particle size of pulverized coal is explored in theory and experiment, and the influence of particle size of single particle on the intensity and frequency of electrostatic signal is analyzed by using finite element simulation software COMSOL. Then, according to the principle of electrostatic measurement, a single particle size measurement method based on transit time and a multi-particle particle size estimation method based on the variation of particle velocity are proposed. Two kinds of materials with different properties, quartz sand and activated carbon, were used in the gas-solid two-phase flow device with the diameter of 74 mm tube. The measuring apparatus used two kinds of electrostatic electrodes with different axial width of 2mm and 10mm. Finally, the effect of water content on particle mass flow is studied by experiments, and the calibration method of correlation coefficient in mass flow measurement is improved. The finite element simulation results show that the particle size can be resolved by measuring the electrostatic signal strength when the charged density of particles is equal. When the particle moves along the axial direction of the ring electrostatic sensor, the influence of the radial position on the frequency of the electrostatic signal is greater than that of the particle size. The experimental results show that the particle size will affect the intensity and frequency of electrostatic signal, and the particle velocity decreases with the increase of particle size when the wind velocity in the pneumatic conveying pipeline is fixed, so the particle size can be estimated by the change of particle velocity. Under the same conditions, the measurement results of particle mass flow rate by electrostatic sensor are different, and the accuracy of measurement can be effectively improved by calibrating the mass flow measurement coefficient according to different water content conditions.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

【参考文献】