Online measurement device and measurement method for NO concentration in high-NO2 and low-NO atmosphere

Abstract

The invention discloses an online measurement device and measurement method for the NO concentration in a high-NO2 and low-NO atmosphere. The online measurement device comprises an ozone generation unit, a connection pipe cleaning unit and a sampling pipe, wherein a connection reaction bin, an NO2 measuring instrument, a second mass flow meter and a first air pump are sequentially connected behind the sampling pipe; and the connection pipe cleaning unit comprises an electromagnetic three-way valve, an activated carbon tube, a current-limiting hole and a second air pump. By adopting a cavity-enhanced absorption spectroscopy, a sampling mode (actual atmosphere of ozone is added) or a zero point mode (actual atmosphere) is set through the electromagnetic three-way valve; absorption spectrum intensity signals of two modes are measured through an NO2 measuring instrument as a sampling spectrum and a reference spectrum respectively, and then NO in the atmosphere is converted into a concentration value of the NO2 through spectral fitting, that is to say, measurement of the NO concentration in the atmosphere environment is achieved, so that the online measurement device and measurement method have the characteristics of being free of NO2 concentration interference, a low detection limit, high sensitivity, high temporal-spatial resolution, high stability and low cost.

Description

technical field [0001] The invention belongs to the technical field of air quality measurement, and relates to the online measurement of NO in the atmosphere, in particular to 2 An on-line measurement device and an on-line measurement method for accurately measuring the concentration of NO in the atmosphere under low NO atmospheric conditions. Background technique [0002] Atmospheric NO is an important primary pollutant in the tropospheric atmosphere. It mainly comes from the high-temperature combustion of nitrogen-containing fuels, including vehicle exhaust, industrial production, and man-made emissions from coal-fired power plants. A small part comes from natural processes such as lightning and microbial release. NO in the atmosphere, NO 2 , O 3 The photochemical cycle between (ozone) constitutes the basis of atmospheric photochemical reactions, so the accurate measurement of NO in the atmosphere is of great significance in atmospheric chemistry. [0003] The concentra...

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Problems solved by technology

[0005] However, when there is high NO in the atmosphere 2 and lower NO when, for example some typical suburban atmospheres, the NO measured by the indirect method X and NO 2 The numerical values ​​are large, and the measured NO is obtained by subtracting the two, even if the instrument measures NO 2 The uncertainty of NOx and NOx is small, which will also lead to a very large absolute error in the concentration of NO obtained by subtraction. Therefore, at high NO 2 Under low NO environmental conditions, the NO measurement results obtained by the existing NO measurement technology have great uncertainty, and it is difficult to achieve accurate measurement

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