Detection method of sulfur dioxide content in sulfur hexafluoride decomposition gas

Abstract

The present invention discloses a method for detecting the content of sulfur dioxide in sulfur hexafluoride decomposition gas, including: selecting a spectral band of SO2, using two narrow spectral bands with central wavelengths of λ1 and λ2 respectively in the above spectral band as detection spectral bands, and the light energy absorption generated by the λ1 spectral band channel is less than the light energy absorption corresponding to the λ2 spectral band; making a blank sample not containing SO2 gas, and detecting the light energy I 10 of the λ1 spectral band and the light energy I 20 of the λ2 spectral band. At the same time, making a SO2 sample with a known concentration of C, and detecting the light energy I′ c1 of the λ1 spectral band and the light energy I′ c2 of the λ2 spectral band; detecting the light energy I′ x1 of SO2 generated by the decomposition of SF6 in the λ1 spectral band and the light energy I′ x2 of the λ2 spectral band, and obtaining the concentration according to the formula. Compared with the existing ultraviolet differential absorption spectroscopy method, there is no spectrometer slit limitation, and the signal-to-noise ratio can be improved; the absorption spectrum of 240 nm to 330 nm is selected to exclude the interference of other gases and improve the detection ability; the method is simple, easy to implement and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of gas analysis methods and relates to a method for detecting the sulfur dioxide content in sulfur hexafluoride decomposition gas. Background Art

[0002] SF 6 Gas is now widely used in switches, transformers, and GIS. 6 The reliable operation of electrical equipment is the key to the safe operation of the power grid. If a fault occurs inside the equipment, SF 6 The gas will decompose under the action of heat and electricity, and react with impurities such as trace water and trace oxygen in the GIS equipment to generate some characteristic gases that are valuable for fault type judgment. The content and change rules of these decomposition products can be used to effectively evaluate the operating status of the equipment. 2 Is the representation of SF 6 The gas is a characteristic indicator of the insulation status inside insulating electrical equipment. Its accurate quantification is of great significance for determining the type and severity of faults inside the insulating equipment.

[0003] Currently commonly used SF 6 Gas decomposition product detection technology mainly includes gas chromatography, mass spectrometry, infrared spectroscopy, electrochemical sensor method, gas detection tube method, ion mobility spectrometry, carbon nanotube sensor, etc. Optical absorption method for detecting SF 6 Decomposed SO 2 Compared with the traditional electrochemical sensor method and gas chromatography, it has obvious advantages. Compared with the electrochemical sensor method, the optical absorption method has strong anti-interference ability, good stability and long life; compared with gas chromatography, the optical absorption method does not require carrier gas, has fast detection speed and less maintenance. The most common optical absorption method currently uses ultraviolet differential absorption spectroscopy, using SO 2 The narrow band spectral absorption characteristics of 190-230nm or 290-310nm are used to detect SF 6 SO in decomposition gas 2 The spectral measurement requires a high-resolution ultraviolet spectrometer. The cost of ultraviolet spectrometers is relatively high, and in order to obtain a high spectral resolution, a very narrow optical slit is required, which will seriously restrict the signal-to-noise ratio of the spectrometer, thus affecting SO 2 Detection limit. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting the sulfur dioxide content in sulfur hexafluoride decomposition gas, which solves the problem of low detection ability of the existing optical absorption method in the prior art.

[0005] The technical solution adopted by the present invention is a method for detecting the sulfur dioxide content in sulfur hexafluoride decomposition gas, comprising the following steps:

[0006] Step 1. Select SO 2 A spectrum that does not contain any other components except SO 2 Other gases besides

[0007] Step 2: The central wavelengths of the above spectrum segments are λ 1 and λ 2 The two narrow spectrum bands of are used as detection spectrum bands, and λ 1 The light energy absorption produced by the spectral channel is less than λ 2 The light energy absorption corresponding to the spectral band;

[0008] Step 3: Make a file that does not contain SO 2 Blank sample of gas, detection lambda 1 Light energy of the spectrum I 10 and λ 2 Light energy of the spectrum I 20 , and at the same time make SO with a known concentration of C 2 Sample, Detection λ 1 The light energy of the spectrum I′ c1 and λ 2 The light energy of the spectrum I′ c2 ;

[0009] Step 4: Detect SF 6 SO produced by decomposition 2 In λ 1 The light energy of the spectrum I′ x1 and λ 2 The light energy of the spectrum I′ x2 , the concentration C is obtained according to the following formula x :

[0010] C x =ax+b

[0011] In the formula,

[0012] The present invention is also characterized in that:

[0013] Step 1 of SO 2 The absorption spectrum is 240~330nm.

[0014] SF using differential absorption spectroscopy 6 Decomposition gas detection equipment for SO 2 Detection of content.

[0015] The beneficial effects of the present invention are as follows: compared with the existing ultraviolet differential absorption spectroscopy, the method for detecting the sulfur dioxide content in the sulfur hexafluoride decomposition gas of the present invention has no limitation of the spectrometer slit and can improve the signal-to-noise ratio; the absorption spectrum of 240nm to 330nm is selected to eliminate the interference of other gases and improve the detection capability; the method is simple, easy to implement and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The invention discloses an absorption spectrum diagram of sulfur dioxide between 240 and 330 nm for the method for detecting the content of sulfur dioxide in sulfur hexafluoride decomposition gas. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The method for detecting the sulfur dioxide content in the decomposition gas of sulfur hexafluoride is based on the differential absorption spectroscopy (DOAS) of SF 6 Decomposing a gas detection device, comprising the following steps:

[0019] Step 1. Select SO 2 In the spectrum of 240nm to 330nm, such as Figure 1 As shown, the central wavelengths are λ 1 and λ 2 The two narrow spectrum bands of are used as detection spectrum bands, and λ 1 The light energy absorption produced by the spectral channel is less than λ 2 The absorption of light energy produced by the spectrum;

[0020] Step 2: Make a file that does not contain SO 2 Blank sample of gas, detection lambda 1 Light energy of the spectrum I 10 and λ 2 Light energy of the spectrum I 20 , and at the same time make SO with a known concentration of C 2 Sample, Detection λ 1 The light energy of the spectrum I′ c1 and λ 2 The light energy of the spectrum I′ c2 ;

[0021] Step 3: Detect SF 6 SO produced by decomposition 2 In λ 1 The light energy of the spectrum I′ x1 and λ 2 The light energy of the spectrum I′ x2 , the concentration C is obtained according to the following formula x :

[0022] Cx =ax+b

[0023] In the formula,

[0024] Through the above manner, the method for detecting the sulfur dioxide content in the sulfur hexafluoride decomposition gas of the present invention, compared with the existing ultraviolet differential absorption spectroscopy, has no limitation of the spectrometer slit and can improve the signal-to-noise ratio; selects the absorption spectrum of 240nm to 330nm, eliminates the interference of other gases, and improves the accuracy of detection; the method is simple, easy to implement and low in cost.

[0025] Example 1

[0026] Select SO 2 In the spectrum of 240nm~330nm, the center wavelengths are λ 1 and λ 2 The two narrow spectrum bands of are used as detection spectrum bands, and λ 1 The light energy absorption produced by the spectral channel is less than λ 2 The light energy absorption corresponding to the spectrum band; the production does not include SO 2 Blank sample of gas, detection lambda 1 Light energy of the spectrum I 10 , I 10 =200000,λ 2 Light energy of the spectrum I 20 , I 20 =190000, then At the same time, a 100 ppm concentration of SO 2 Sample, Detection λ 1 The light energy of the spectrum I′ c1 and λ 2 The light energy of the spectrum I′ c2 , I c1 =73576,I c2 =63246, then

[0027]

[0028] Detection SF 6 SO produced by decomposition 2 In λ 1 The light energy of the spectrum I′ x1 and λ 2 The light energy of the spectrum I′ x2 , then SF 6 SO produced by decomposition 2 The concentration is:

[0029] C x =ax+b=1000x-51.293

[0030] Measured light intensity I′ x1 =17042,I′ x2 =159337, then the actual gas concentration is

[0031] Example 2

[0032] Select SO 2 In the spectrum of 240nm~330nm, the center wavelengths are λ 1 and λ 2 The two narrow spectrum bands of are used as detection spectrum bands, and λ 1 The light energy absorption produced by the spectral channel is less than λ 2 The light energy absorption corresponding to the spectrum band; the production does not include SO 2 Blank sample of gas, detection lambda 1 Light energy of the spectrum I 10 , I 10 =200000,λ 2 Light energy of the spectrum I 20 , I 20 =190000, then At the same time, a 100 ppm concentration of SO 2 Sample, Detection λ 1 The light energy of the spectrum I′ c1 and λ 2 The light energy of the spectrum I′ c2 , I c1 =73576,I c2 =63246, then

[0033]

[0034] Detection SF 6 SO produced by decomposition 2 In λ 1 The light energy of the spectrum I′ x1 and λ 2 The light energy of the spectrum I′ x2 , then SF 6 SO produced by decomposition 2 The concentration is:

[0035] C x =ax+b=1000x-51.293

[0036] The measured light intensity is I′ x1 =121306,I′ x2 =109621, then the actual gas concentration is

[0037] Example 3

[0038] Select SO 2 In the spectrum of 240nm~330nm, the center wavelengths are λ 1 and λ 2 The two narrow spectrum bands of are used as detection spectrum bands, and λ 1 The light energy absorption produced by the spectral channel is less than λ 2 The light energy absorption corresponding to the spectrum band; the production does not include SO 2 Blank sample of gas, detection lambda 1 Light energy of the spectrum I 10 , I 10 =25000,λ 2 Light energy of the spectrum I 20 , I 20 =150000, then At the same time, a 100 ppm concentration of SO 2 Sample, Detection λ 1 The light energy of the spectrum I′ c1 and λ 2 The light energy of the spectrum I′ c2 , I c1 =91970,I c2 =49931, then

[0039]

[0040] Detection SF 6 SO produced by decomposition 2 In λ 1 The light energy of the spectrum I′ x1 and λ 2 The light energy of the spectrum I′ x2 , then SF 6 SO produced by decomposition 2 The concentration is:

[0041] C x =ax+b=1000x-510.83

[0042] Measured light intensity I′ x1 =151633,I′ x2 =86543, then the actual gas concentration is

[0043] Example 4

[0044] Select SO 2 In the spectrum of 240nm~330nm, the center wavelengths are λ 1 and λ 2 The two narrow spectrum bands of are used as detection spectrum bands, and λ 1 The light energy absorption produced by the spectral channel is less than λ 2The light energy absorption corresponding to the spectrum band; the production does not include SO 2 Blank sample of gas, detection lambda 1 Light energy of the spectrum I 10 , I 10 =25000,λ 2 Light energy of the spectrum I 20 , I 20 =150000, then At the same time, a 100 ppm concentration of SO 2 Sample, Detection λ 1 The light energy of the spectrum I′ c1 and λ 2 The light energy of the spectrum I′ c2 , I c1 =91970,I c2 =49931, then

[0045]

[0046] Detection SF 6 SO produced by decomposition 2 In λ 1 The light energy of the spectrum I′ x1 and λ 2 The light energy of the spectrum I′ x2 , then SF 6 SO produced by decomposition 2 The concentration is:

[0047] C x =ax+b=1000x-510.83

[0048] The measured light intensity is I′ x1 =112332,I′ x2 =62217, then the actual gas concentration is

Claims

1. A method for detecting the sulfur dioxide content in sulfur hexafluoride decomposition gas, characterized in that: The following steps are involved: Step 1, selecting a spectrum of SO2, and the spectrum does not contain other gases except SO2; Step 2: The central wavelengths in the above spectrum segments are and The two narrow spectrum bands of are used as detection spectrum bands, and The light energy absorption produced by the spectral channel is less than The light energy absorption corresponding to the spectral band; Step 3: Prepare a blank sample without SO2 gas and detect Light energy in the spectrum and Light energy in the spectrum , and at the same time make a known concentration of SO2 samples, detection Light energy in the spectrum and Light energy in the spectrum ; Step 4: Detect SO2 produced by SF6 decomposition Light energy in the spectrum and Light energy in the spectrum , the concentration is obtained according to the following formula : ； SF6 decomposition gas detection equipment using differential absorption spectroscopy technology is used to detect SO2 content; In step 4, , ; In step 4, .

2. The method for detecting the sulfur dioxide content in sulfur hexafluoride decomposition gas according to claim 1, characterized in that: The SO2 absorption spectrum described in step 1 is 240~330nm.

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