Research On The Point In-situ Monitoring Device Of Flue Gas For Power Plants

In the power industry, the need for energy saving and consumption reducing has become more stringent. The measurement of flue gas component, as a vital part of CEMS, can not only used to get the coal quality information from the flue gas parameters to realise on-line coal consumption calculation for coal fired power plants, but also can get gross concentration of gaseous pollutant emission which can evaluate the implementation of the current emission standards by combining with other parameters of CEMS. Currently, the traditional emissions measuring technologies for flue gas are generally extractive systems (source-level or dilution) or cross-stack in-situ system. These systems usually involve in a series of disadvantages including heated sampling lines, water vapour removing which can not realise the analysis to water vapour, dust removing, calibration difficulties, complicated systems and high maintainance, which are against benefit of power plants. According to this phenomenon, this thesis brings forward the research on the point in-situ monitoring device of flue gas for power plants.This thesis designed point in-situ monitoring device of flue gas for power plants including point in-situ infrared gas sensors, gas distribution device and measuring device for oxygen. Two point in-situ infrared sensors are designed based on the principle of absorbing of infrared spectrum, one of which is to measure the component of CO2 and CO, the other is to measure the component of SO2, NO and H2O. The signals of sensors have been collected to be fitted on the condition of different gas component with different mixture ratio. Through fitting by using linear polynomial, quadratic polynomial and cubic polynomial, preferable fitting mutiple regression equation was selected. Acorrding to the equation, measuring concentration was calculated which then be compared with the concentration of calibrating gas. An experiment to correct the interference to SO2 and NO caused by H2O has been carried out. The results of the tests show that the relative error of measurement is within 5% which means the experiment is feasible. And a device to measure oxygen based on Zirconium oxide analysis has been designed. Through the experiment, an integrated point in-situ monitoring device of flue gas for power plants has been established.