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Detection method for concentration of low-concentration NO and SO2 mixed gas

A mixed gas and concentration detection technology, applied in the direction of color/spectral characteristic measurement, etc., can solve the problems of inaccurate calculation of concentration, inconspicuous spectral absorption, inability to accurately monitor NO concentration, etc.

Active Publication Date: 2017-12-15
CHONGQING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First, at low concentrations below 100ppm, SO 2 The spectral absorption at the 280-320nm band is not obvious, and the signal-to-noise ratio of the characteristic signal is low, so it is impossible to accurately calculate the SO 2 concentration, and thus cannot accurately analyze the spectral signal of NO from the spectral signal of the mixed gas, and cannot accurately monitor the concentration of NO
Secondly, directly use the least squares method to calculate NO and SO at the same time 2 The concentration error is as high as 10%, and the calculation error is even greater at low concentrations below 100ppm, which makes it difficult to meet the accuracy requirements of concentration detection
Therefore, under the requirement of ultra-low emissions, use the above classic DOAS method to monitor low concentrations of NO and SO below 100ppm 2 It is difficult to meet the detection accuracy requirements

Method used

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  • Detection method for concentration of low-concentration NO and SO2 mixed gas
  • Detection method for concentration of low-concentration NO and SO2 mixed gas
  • Detection method for concentration of low-concentration NO and SO2 mixed gas

Examples

Experimental program
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Embodiment 1

[0100] In this embodiment, the concentration of NO gas is 75ppm, SO 2 NO and SO with a gas concentration of 30ppm 2 Mix the experimental gas, adopt the method of the present invention to carry out the concentration detection experiment on it, detect wherein NO gas and SO 2 The concentration of each gas, the specific steps are as follows:

[0101] 1) Obtain and record SO separately in advance 2 Differential absorption cross section of gas in the 200-230nm spectral band Differential absorption cross section σ of NO gas in the 200-230nm spectral band f,NO (λ b ), and different concentrations of SO 2 Differential absorbance of gas in the 200-230nm spectral band And from SO 2 Differential absorption cross section of gas in the 200-230nm spectral band SO 2 Differential absorption cross section of gas in the 206-212nm spectral band

[0102] The basic data in this step can be obtained through the aforementioned methods.

[0103] 2) NO and SO to be measured 2 The mixed...

Embodiment 2

[0125] In this embodiment, the concentration of NO gas is 1ppm, SO 2 Gas concentrations of 1ppm NO and SO 2 Mix the experimental gas, adopt the method of the present invention to carry out the concentration detection experiment on it, detect wherein NO gas and SO 2 The concentration of each gas; the detection result is that the NO gas concentration determined by detection is 0.95ppm, and the relative error with the real NO gas concentration of 1ppm is 5%, and the SO gas concentration determined by detection 2 The gas concentration is 0.96ppm, which is the same as the real SO 2 The relative error of gas concentration 1ppm is 4%. The results showed that in NO, SO 2 When the gas concentration is small, although the relative error of the detection result increases compared with Example 1, the average value of the detection error is within the allowable range of 5%, which proves that the method of the present invention is feasible.

Embodiment 3

[0127] In addition, through a large number of experiments on the invention of low concentration NO and SO 2 The concentration detection method of mixed gas is verified, and confirms that the method of the present invention can be aimed at NO and SO of low concentration below 100ppm 2 Effective concentration detection of mixed gas, the lower limit of detection concentration can reach 0.15ppm, the detection accuracy and sensitivity are high, SO in mixed gas 2 When the concentration is 4-30ppm, the relative error is less than 2%, SO 2 When the concentration is less than 4ppm, the relative error is less than 4%; when the NO concentration in the mixed gas is 6-75ppm, the error is less than 2%, and when the NO concentration is less than 6ppm, the relative error is less than 5%. It can be seen that the method of the present invention solves the problem of NO and SO at low concentrations below 100ppm by the concentration detection method of the prior art. 2 The mixed gas is difficul...

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Abstract

The invention provides a detection method for the concentration of low-concentration NO and SO2 mixed gas. By utilizing the characteristic that the spectral absorption interference between SO2 and NO gas at the 206-212nm wave band is low, through data extraction, spectral absorption data of the SO2 gas in the 206-212nm wave band is separated, and the concentration of the SO2 gas is determined at first; further, by utilizing a spectral superposition principle of the mixed gas and spectral absorption data of a 200-230nm wave band range where the spectral absorption of the SO2 and NO gas is seriously mixed and superposed, the spectral absorption data at the 200-230nm wave band is analyzed out, and therefore the concentration of the NO gas is determined, so that the respective concentration detection of the SO2 gas and the NO gas in the NO and SO2 mixed gas is achieved; the method can have good detection accuracy, and the problem is solved that concentration detection methods in the prior art cannot meet the requirement of detection precision regarding the low-concentration No and SO2 mixed gas at 100 ppm or below; meanwhile the amount of data involved in the whole detecting process is small, and therefore the method is conducive to speeding up the calculation of detection processing and improving the real-time performance of the detection.

Description

technical field [0001] The invention relates to the technical field of flue gas emission detection, in particular to a low-concentration NO and SO 2 Concentration detection method of mixed gas. Background technique [0002] In order to reduce the pollution of the environment, my country has formulated and implemented new regulations on the control of ultra-low emissions of polluting gases, which stipulates that SO 2 Concentration below 35ppm, NO concentration below 75ppm, NO 2 The concentration is lower than 50ppm. Due to NO and SO 2 It is the main harmful gas component in the flue gas, so for the low concentration of NO and SO with the concentration below 100ppm 2 The concentration detection technology of mixed gas is one of the main application technologies for the detection of harmful gases in flue gas. [0003] The classic ultraviolet differential optical absorption (DOAS) technology has high reliability, high precision, low cost, and can simultaneously monitor NO ...

Claims

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Application Information

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IPC IPC(8): G01N21/33
CPCG01N21/33
Inventor 郭永彩高潮彭波
Owner CHONGQING UNIV
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