Design Of Flue Gas Analyzer Based On Ultraviolet Differential Algorithm

In recent years,the phenomena of global warming and Arctic glacier melting have become more and more obvious.The main causes of these phenomena are the burning of crop straw,the exhaust gas from industrial production,the exhaust gas from transportation,and the burning of domestic waste,which have caused great harm to our environment.In order to improve this situation,the environmental protection department of our country has formulated relevant laws and regulations as well as a series of emission standards of polluted gases to improve environmental problems.Flue gas analyzer came into being under this background.At present,there are many methods of flue gas detection at home and abroad.The main principles of flue gas detection in the world include electrochemical principle,microflow sensor principle,non-infrared scattering principle and so on.Most flue gas analyzers in the domestic market use spectral analysis method,which mainly includes infrared spectroscopy and ultraviolet spectroscopy.These two categories belong to the category of spectral analysis in principle,so their measuring principles are based on Beer-Lambert law.Beer-Lambert’s law can measure the concentration of various gases under ideal conditions,but there are a lot of other impurities and colloidal solutions in the air during the actual detection process.They also absorb the incident light.That is to say,the characteristic absorption of the measured gas molecules is not only the attenuation of the incident light,but also the attenuation of the incident light.Scattering of other impurities,etc.In this case,Beer-Lambert law will no longer be applicable,and it will not be able to accurately measure the concentration of common polluted gases.In order to solve the scattering problem,the actual spectra collected by the ultraviolet difference algorithm are divided into two parts: fast-changing and slow-changing.The characteristic absorption spectra of gas molecules show fast-changing,while the absorption spectra and scattering of other impurities show slow-changing.Then,based on Beer-Lambert’s law,the fast-varying spectrum and slow-varying spectrum in the actual spectrum are separated,and the characteristic absorption spectrum of gas pollutants is extracted.Then,the real-time concentration of the measured gas can be retrieved by the fitting and inversion of the spectrum,the polynomial fitting of the data and the translation of the spectrum.It solves the scattering problem well and makes Beer-Lambert’s law be used to measure the real-time concentration of flue gas again.Finally,the performance of the flue gas analyzer based on ultraviolet difference calculation was tested in laboratory and field under the same conditions as that of the flue gas analyzer based on other principles.The results show that the performance of the flue gas analyzer based on UV differential absorption spectroscopy fully meets the standards of the State Environmental Protection Agency compared with the non-UV differential algorithm.The response time is within 50 s,the zero drift and range drift are within 0.6%FS,the linear error is within 1.6%,the detection limit is within 0.5% FS,and the interference effect is also 0.5%.These performance test results show that the flue gas analyzer based on ultraviolet difference calculation can accurately detect the atmospheric environment,industrial boiler exhaust gas,coal-fired power plant exhaust gas and so on.The field concentration measurement results also show that the measurement accuracyerror of the measured gas is within 3%,which fully meets the standards of the State Environmental Protection Agency.