Study Of On-line Monitoring Concentration Of Flue Gases Based On DOAS

The basic principle of Differential Optical Absorption Spectroscopy (DOAS) is further studied in the paper. In-situ monitoring of NO、NO2、SO2 and NH3, which are derived from the flue gas exhaust of coal-burning boiler, chemistry, metallurgy, cement and furnace, is realized with the method of spectrum analysis. Some relevant works have been done and some conclusions also have been drawn in this report.1、Absorption characteristic of NO、NO2、SO2 and NH3 have been studied and absorption cross section of them are got through experiment.2、The nonlinear absorption of gas has a great influence on monitoring gas concentration in DOAS method. A new method for compensating nonlinearity is put forward, namely, fitting a compensating function to the corresponding connection between retrieval total columns and the ratio which is between the differential pressure corresponding to true concentration and the one corresponding to the retrieved concentration. The fitted function is be used to compensate for nonlinearity of retrieved concentrations. The experimental results show that the measurement results will be well compensated with the higher precision and well repeatability by using this method.3、The core algorithm of simultaneous measurement of concentration and temperature of flue gas is developed. Information fusion technology is applied and the algorithm can be self-adapted according to the variation of concentration. The system based on the algorithm has large dynamic measurement range.4、The error produced in this system is analyzed deeply, and my own opinion to improve the accuracy of measurement of this system was proposed.