Research On The Velocity Of Flue Gas And Dust Concentration Based On The Electrostatic Cross-Correlation Method

In the power industry, the flue gas emission monitoring is very important, for not only it can be used to determine the concentration of dust emission and mass flow, evaluate the dust collection equipment performance and efficiency, check the implementation of the current emission standards, but also it can be used to get the coal quality information from the flue gas parameters, as well as on-line coal consumption calculation for coal fired power plant The traditional flow measurement techniques for flue gas are averaging pitot, ultrasonic transit time and thermal mass. However, these kinds of technology will meet the problems caused by the ash particulates and high moisture in flue gas. The new technology based on electrodynamic cross-correlation was developed for gas-solid two phase flow to measure the mass flow of solid. The feasibility of using the electrodynamic cross-correlation method to test the velocity of flue gas and the dust concentration was discussed in this paperAccording to the dust characteristic, the experimental bench was designed for the velocity and dust concentration measuring based on contact electrostatic correlation method. The experimental bench is composed of electrostatic sensors module, detecting circuit, data acquisition system, signal processing system and computation software. In order to increase the calculation speed, the Fast Fourier Transform arithmetic was used for Cross-Correlation function. The velocity and the flow rate are calculated by the correlation analysis of upstream signal and downstream signal. According to the experiment phenomenon and result, electrostatic Cross-Correlation method used to measure the velocity and flow rate of dust particulate is feasible. When the velocity of particulate is higher than 8 m/s, the relative error of measurement is within 5%. In this paper, a series of testing, such as the distance between the sensor and frequency by which signal is sampled on the accuracy of the mean velocity measurement of particles, have been carried out. The result of tests shows that the distance between the sensors in a certain range has little influence on the accuracy of measurement, but the frequency with which electrodynamic signals are digitized has great influence. The relationship between the mass flow rate and RMS is established through the concentration of experiments.