Method for detecting ultraviolet differential nitrogen dioxide gas

Abstract

The invention discloses a method for detecting ultraviolet differential nitrogen dioxide gas. The method comprises the following steps: collecting sample gas; making a standard curve: introducing 99.999% nitrogen into the gas chamber at a flow rate of 2L/min, collecting an N2 spectrum and storing data, then introducing NO2 standard gas, and collecting NO2 spectrum data; and by utilizing a Lambert-Beer law, calculating the molar absorption coefficient of NO2 based on a 100% NO2 standard absorption curve, then, substitutingthe molar absorption coefficient of NO2 into data of the first several groups of spectrums, and calculating the actual concentration, wherein it is obtained according to multiple experiments that deviation exists between the actual concentration and the theoretical concentration, the actually calculated concentration needs to be corrected, and after correction through a third-order function, the actual concentration and the theoretical concentration are within a required error range. According to the method, the concentration of NO2 in the gas is measured by utilizing an ultraviolet spectrum differential technology, and the method has good data accuracy and repeatability and wide application range.

Description

technical field [0001] The invention belongs to the field of gas detection, and in particular relates to a detection method for ultraviolet differential nitrogen dioxide gas. Background technique [0002] Nitrogen dioxide (NO 2 ) is a brown-red, highly reactive gaseous substance, also known as nitrogen peroxide. Nitrogen dioxide plays an important role in the formation of ozone. Man-made nitrogen dioxide mainly comes from the release of high-temperature combustion processes, such as vehicle exhaust and boiler exhaust emissions. Nitrogen dioxide is also a cause of acid rain, which has a variety of environmental effects, including: effects on competition and composition changes between wetland and terrestrial plant species, reduction of atmospheric visibility, acidification of surface water, eutrophication Oxygenation (a lack of oxygen caused by algae blooms rich in nutrients such as nitrogen and phosphorus) and increased levels of toxins in water bodies that are harmful to...

AI Technical Summary

Problems solved by technology

[0004] While currently measuring NO 2 The concentration is achieved by adding a NOx converter on the system, converting the NO 2 Converted to NO, then measure the concentration of NO, NO can not be measured directly 2 concentration

The catalyst in the nitrogen oxide converter will age rapidly over time, and the conversion efficiency will generally drop from above 95% to below 70% after a few months, which cannot continue to meet the environmental protection industry's requirement for a nitrogen oxide converter conversion efficiency of 95%. % above standard requirements

In addition, the replacement of the catalyst every few months also increases the operation and maintenance cost and frequency of the equipment

In addition, the nitrogen oxide converter needs to work at a high temperature of about 400 ° C. At this temperature, the SO in the exhaust gas measured at the same time 2 Components will undergo reverse reaction, part of SO 2 will react to generate S 2 o 3 and other oxides, SO 2 The measured value will be lower

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