Insulating gas perfluoroalkyl nitrile decomposition product detection device and method

Abstract

This invention belongs to the field of gas detection technology, specifically relating to a device and method for detecting the decomposition products of perfluoroalkyl nitrile (PFAN) in insulating gases. The device includes a gas acquisition module, a pretreatment module, a multi-technology co-processing module, a detection chamber, and an intelligent data processing and control system. The gas acquisition module collects and concentrates gas samples through a sampling unit in the gas chamber and a low-temperature enrichment unit. The pretreatment module purifies the gas and converts complex components through a high-efficiency filter, a dryer, and a catalytic conversion unit. The multi-technology co-processing module uses a micro gas chromatography unit to separate the gas and an infrared spectroscopy unit for qualitative analysis. The gas-sensitive sensor array in the detection chamber enables multi-dimensional detection. The intelligent data processing and control system's storage module stores multiple databases, and the analysis module calls these databases to analyze data from multiple modules, achieving sampling, detection, and intelligent analysis of the decomposition products. This solves the problems of missed detections, lack of specificity, and low efficiency in existing detection methods.

Description

Technical Field

[0001] This invention belongs to the field of gas detection technology, specifically relating to a device and method for detecting the decomposition products of perfluoroalkyl nitrile in insulating gases. Background Technology

[0002] Perfluoroalkyl nitrile (C4F7N), as an environmentally friendly insulating gas, possesses low global warming potential (GWP) and excellent insulation properties, making it an ideal alternative to traditional SF6 gas. However, during the operation of electrical equipment, C4F7N may decompose due to electric arcing, partial discharge, or overheating, producing various harmful byproducts such as CF3CN, CF4, CO, and COF2. Accurately detecting the types and concentrations of these decomposition products is crucial for assessing the insulation condition of equipment and diagnosing faults.

[0003] Currently, the detection of perfluoroalkyl nitriles and their decomposition products mainly relies on gas chromatography and mass spectrometry. The disadvantages include expensive and bulky equipment, requiring complex sample pretreatment and vacuum environment maintenance, making it unsuitable for rapid on-site detection, and making it difficult to simultaneously guarantee comprehensiveness and accuracy. Furthermore, existing qualitative techniques primarily rely on existing standard gases, which often lack specificity and efficiency for the detection of perfluoroalkyl nitrile decomposition products. This results in difficulties in the qualitative identification of some decomposition products and missed detections due to poor column separation, failing to meet the urgent needs of on-site maintenance of electrical equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a device and method for detecting the decomposition products of perfluoroalkyl nitrile in insulating gases, which solves the problems of missed detections, lack of specificity and efficiency in existing detection methods.

[0005] This invention is achieved through the following technical solution: This invention discloses a device for detecting the decomposition products of perfluoroalkyl nitrile in insulating gases, comprising a gas acquisition module, a gas pretreatment module, a multi-technology combined module, a detection chamber, and an intelligent data processing and control system; The gas acquisition module includes a gas chamber sampling unit and a low-temperature enrichment unit connected in sequence; The gas pretreatment module includes a high-efficiency filter, a dryer, and a catalytic conversion unit connected in sequence; The multi-technology module includes a micro gas chromatography unit and an infrared spectroscopy unit connected in sequence; The detection chamber is equipped with a gas-sensitive sensor array, which includes ZnO nanosheet sensors, In2O3 microsphere sensors, WO3 nanowire sensors, Cu-MoS2 nanosheet sensors and Ni-WS2 nanosheet sensors. The low-temperature enrichment unit is connected to a high-efficiency filter, the catalytic conversion unit is connected to a micro gas chromatography unit, and the infrared spectroscopy unit is connected to a gas sensor array. The miniature gas chromatography unit, infrared spectroscopy unit, and gas sensor array are all connected to the intelligent data processing and control system. The intelligent data processing and control system includes a storage module and an analysis module. The storage module stores a gas chromatography standard curve library, an infrared spectroscopy standard curve library, an infrared standard spectrum library, a decomposition product literature library, and a Gaussian computational simulation spectral database. The analysis module is used to call the database stored in the storage module to analyze the data output by the micro gas chromatography unit, infrared spectroscopy unit, and gas sensor array.

[0006] Furthermore, the equipment gas chamber sampling unit includes a miniature vacuum pump and an eddy current probe with a corrosion-resistant PTFE coating; the eddy current probe is used to insert into the equipment gas chamber, and the miniature vacuum pump is used to pump the gas in the equipment gas chamber to the cryogenic enrichment unit.

[0007] Furthermore, the low-temperature enrichment unit includes a temperature control system, a semiconductor refrigeration chip, a gas enrichment device, and a desorption system; the semiconductor refrigeration chip is connected to the gas enrichment device to achieve deep cryogenic treatment at -50°C and concentrate trace decomposition products. The temperature control system is used to control the temperature of the desorption system, which is connected to the high-efficiency filter.

[0008] Furthermore, the high-efficiency filter uses a PTFE membrane with micron-sized pores to remove interfering components such as particulate matter; Dryers are used to remove moisture from gases; The catalytic conversion unit supports Pt / TiO2 nanocatalysts to convert the unstable product HF into detectable F. - ion.

[0009] Furthermore, the micro gas chromatography unit is equipped with a multi-channel micro-packed column and a thermal conductivity detector, making it compatible with a variety of fluorine-containing insulating gases; The multichannel micro-packed column is one or more of the following: silica bonded phase C8 column, graphitized carbon black column, and molecular sieve column.

[0010] Furthermore, the infrared spectral unit includes a long-path gas cell and an infrared spectrometer. The long-path gas cell has three optical paths, which can be switched in three levels according to the optical path requirements. The optical path switching of the long-path gas cell is achieved by a stepper motor. The optical path switching range is 30m, 50m, and 100m. The long-path gas cell is connected to the micro gas chromatography unit.

[0011] Furthermore, the detection chamber is connected to the gas optical path cell, and ZnO nanosheet sensors, In2O3 microsphere sensors, WO3 nanowire sensors, Cu-MoS2 nanosheet sensors, and Ni-WS2 nanosheet sensors are arranged in a matrix in the detection chamber to realize the detection of multiple decomposition products.

[0012] Furthermore, the analysis module has a built-in intelligent analysis model for decomposition products. This model uses the chromatographic data output by the micro gas chromatography unit and the gas chromatography standard curve library to obtain qualitative and quantitative analysis results of some decomposition products. The intelligent analysis model for decomposition products uses the infrared spectral data output by the infrared spectral unit and the infrared spectral standard curve library to obtain qualitative and quantitative analysis results of another part of the decomposition products. The intelligent analysis model for decomposition products uses a literature database of decomposition products to identify overheating decomposition products and discharge decomposition products.

[0013] This invention also discloses a detection method based on the aforementioned perfluoroalkyl nitrile decomposition product detection device for insulating gases, comprising the following steps: Step 1, Gas Collection: Gas is collected through the gas chamber sampling unit of the equipment, and the gas is enriched by the low temperature enrichment unit; Step 2, Gas Pretreatment: The collected gas flows out from the low-temperature enrichment unit, is filtered by a high-efficiency filter, dried by a dryer, and converted by a catalytic conversion unit before flowing into the micro gas chromatography unit. Step 3, Chromatographic separation: After the gas enters the micro gas chromatography unit for detection, it outputs chromatographic data and transmits the chromatographic data to the intelligent data processing and control system. The gas chromatography standard curve library is called to process the chromatographic data and obtain the types and contents of the first part of the decomposition products. Step 4, Spectral Analysis: The gas flowing out of the micro gas chromatography unit enters the infrared spectroscopy unit, is detected, and outputs infrared spectral data. The infrared spectral data is then transmitted to the intelligent data processing and control system, which calls the infrared spectral standard curve library, the infrared standard spectrum library, and the Gaussian computational simulation spectral database to process the infrared spectral data and obtain the types and contents of the decomposition products in the second part. Step 5: Gas sensor array detection: Gas flowing out of the long optical path gas cell enters the detection gas chamber, is detected by the gas-sensitive sensor array, and outputs concentration data. The concentration data is then transmitted to the intelligent data processing and control system to obtain the types and contents of the third part of the decomposition products. Step 6: Collect the data from the three parts in Steps 3-5, and after calling the decomposition product literature library to classify the decomposition products, generate a complete test report.

[0014] Furthermore, the infrared spectral unit includes a long-path gas cell and an infrared spectrometer. The long-path gas cell has three optical paths, which can be switched in three levels according to the optical path requirements. The optical path switching of the long-path gas cell is achieved by a stepper motor. The optical path switching range is 30m, 50m, and 100m. In step 4, the infrared spectral unit detection is divided into the following different cases: 1. If the micro gas chromatography unit does not detect any components other than C4F7N and CO2, the infrared spectroscopy unit will first switch the optical path to 100 m for infrared spectroscopy detection. If the infrared spectrometer detects a new absorption peak and does not exceed the detection limit, the detection data will be transmitted to the intelligent data processing and control system, and the gas will enter the gas-sensitive sensor array unit for further detection. If the infrared spectrometer detects a new absorption peak that exceeds the detection limit, the optical path will be switched to a smaller range for re-detection, and the detection data will be transmitted to the intelligent data processing and control system. The gas will then enter the gas-sensitive sensor array unit for further detection. 2. If the micro gas chromatography unit detects other components besides C4F7N and CO2, the infrared spectroscopy unit will first switch the optical path to 30 m to perform infrared spectroscopy detection and obtain the detection results. If the infrared spectrometer detects a new absorption peak, the optical path is switched to 50m to continue detection. If the detection result of 50m optical path is consistent with the detection result of 30m optical path, the detection data is transmitted to the intelligent data processing and control system, and the gas enters the gas-sensitive sensor array unit for further detection. If a new absorption peak appears in the 50m optical path detection result, the detection is switched to a 100m optical path and the generated detection data is transmitted to the intelligent data processing and control system. After the detection is completed, the gas enters the gas-sensitive sensor array unit for further detection.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The purpose of this invention is to provide a device for detecting the decomposition products of perfluoroalkyl nitrile in insulating gases. The device includes a gas acquisition module, comprising a gas chamber sampling unit and a low-temperature enrichment unit. The gas chamber sampling unit directly collects gas samples containing the decomposition products of perfluoroalkyl nitrile from the device under test, avoiding gas component escape or interference from external impurities during sampling. The low-temperature enrichment unit uses low-temperature condensation technology to enrich low-concentration decomposition products in the sampled gas, improving the sensitivity of subsequent detection. It also selectively retains target components at low temperatures and preliminarily separates water vapor, high-boiling-point impurities, etc., reducing the burden on the pretreatment module.

[0016] The gas pretreatment module filters out solid particles, oil, and other mechanical impurities from the gas through a high-efficiency filter to prevent clogging of subsequent pipelines or contamination of detection elements, ensuring gas cleanliness; it removes moisture from the gas through a dryer to avoid water vapor interfering with gas chromatography separation efficiency, infrared spectral absorption signals, or the performance of gas sensors; and it converts the complex decomposition products of perfluoroalkyl nitriles into easily detectable small molecules through a catalytic conversion unit.

[0017] The multi-technology co-processing module includes a gas chromatography unit and an infrared spectroscopy unit. The micro gas chromatography unit utilizes the differences in adsorption / desorption capabilities of chromatographic columns for different gas components to achieve efficient separation of decomposition products. By comparing with a gas chromatography standard curve library, the concentration of each component is calculated, providing accurate quantitative data. The infrared spectroscopy unit identifies the chemical structure of decomposition products by detecting the characteristic absorption spectra of gas molecules to infrared light and comparing them with an infrared standard spectrum library. Combined with the infrared spectroscopy standard curve library, the absorbance of characteristic functional groups is analyzed to assist gas chromatography in the quantification of complex components.

[0018] The detection chamber is equipped with a gas-sensitive sensor array, which supplements the detection of various fluorine-containing gases by using different types of sensors. Through the coordinated response of multiple sensors, the identification accuracy and anti-interference ability of complex gas components are improved.

[0019] The detection results from the gas-sensitive sensor array are complemented and cross-validated by the data from the miniature gas chromatography unit and the infrared spectroscopy unit through an intelligent data processing and control system, improving detection accuracy. During gas testing, the gas first flows into the miniature gas chromatography unit, then into the infrared spectroscopy unit, and finally into the gas-sensitive sensor array. Through the mutual complementarity and cross-validation of multiple detection technologies, the accuracy and comprehensiveness of quantitative and qualitative analysis of perfluoroalkyl nitrile decomposition products are improved. The built-in databases enhance the efficiency and convenience of qualitative and quantitative analysis of decomposition products and provide diagnostic capabilities for discharge or overheating faults in high-voltage gas-insulated equipment.

[0020] Furthermore, since the concentration of decomposition products cannot be predicted in advance during on-site operation and maintenance, this design is intended to accommodate the detection needs of decomposition products at the same concentration under different equipment malfunctions, avoiding the problem of mismatch between range and concentration in single-path detection. The infrared spectral unit of this invention is divided into different cases for detection: 1. If the micro gas chromatography unit does not detect any components other than C4F7N and CO2, the infrared spectroscopy unit will first switch the optical path to 100 m for infrared spectroscopy detection. If the infrared spectrometer detects a new absorption peak and does not exceed the detection limit, it indicates that the range is appropriate and there is no need to select a smaller range for detection. The detection data will then be transmitted to the intelligent data processing and control system, and the gas will enter the gas-sensitive sensor array unit for further detection as a supplementary detection. If the infrared spectrometer detects a new absorption peak that exceeds the detection limit, it means that the 100m range is too large. Although it can still perform qualitative analysis, it will cause inaccurate quantitative analysis. Therefore, the optical path needs to be switched to achieve accurate quantitative analysis. The optical path is switched to 50m for re-detection, and the detection data is transmitted to the intelligent data processing and control system. The gas enters the gas-sensitive sensor array unit for further detection as a supplementary detection. 2. If the micro gas chromatography unit detects components other than C4F7N and CO2, it means that the concentration of most components may be within the detectable range of 30 m optical path. The infrared spectroscopy unit will then prioritize switching the optical path to 30 m for infrared spectroscopy detection. If the infrared spectrometer detects a new absorption peak, it means that there is a possibility of missing lower concentration components under the 30 m optical path. In this case, the optical path will be switched to 50 m for further detection. If the detection result of 50 m optical path is consistent with the detection result of 30 m optical path, the detection data will be transmitted to the intelligent data processing and control system, and the gas will enter the gas-sensitive sensor array unit for further detection. If a new absorption peak appears in the 50m optical path detection result, the detection is switched to a 100m optical path and the generated detection data is transmitted to the intelligent data processing and control system. After the detection is completed, the gas enters the gas-sensitive sensor array unit for further detection. Attached Figure Description

[0021] Figure 1 A diagram illustrating the overall working process of the qualitative and quantitative analysis method for C4F7N decomposition products; Figure 2 This is a schematic diagram of the device structure of the present invention; Figure 3 This is a schematic diagram of the gas-sensitive sensor array structure of the present invention.

[0022] In the diagram: 1. Gas acquisition module; 2. Gas pretreatment module; 3. Multi-technology combined module; 4. Detection chamber; 5. Intelligent data processing and control system; 101. Equipment chamber sampling unit; 102. Eddy current probe; 103. Miniature vacuum pump; 104. Low-temperature enrichment unit; 201. High-efficiency filter; 202. Dryer; 203. Catalytic conversion unit; 301. Miniature gas chromatography unit; 302. Infrared spectroscopy unit; 401. ZnO nanosheet sensor; 402. In2O3 microsphere sensor; 403. WO3 nanowire sensor; 404. Cu-MoS2 nanosheet sensor; 405. Ni-WS2 nanosheet sensor. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0024] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0025] like Figure 2 As shown, this invention discloses a device for detecting the decomposition products of perfluoroalkyl nitrile insulating gases, comprising: Gas acquisition module 1 includes a gas chamber sampling unit 101 and a low-temperature enrichment unit 104; Gas pretreatment module 2 includes a high-efficiency filter 201, a dryer 202, and a catalytic conversion unit 203; The multi-technology module 3 includes a micro gas chromatography unit 301 and an infrared spectroscopy unit 302; Detection chamber 4, which contains an array of gas-sensitive sensors, such as... Figure 3 As shown, the gas sensor array includes one ZnO nanosheet sensor 401, one In2O3 microsphere sensor 402, one WO3 nanowire sensor 403, one Cu-MoS2 nanosheet sensor 404, and one Ni-WS2 nanosheet sensor 405.

[0026] The intelligent data processing and control system 5 includes an analysis module and a storage module.

[0027] like Figure 2 As shown, the equipment gas chamber sampling unit 101 uses an eddy current probe 102 with a corrosion-resistant PTFE coating, which can be directly inserted into the equipment gas chamber. It has a built-in micro vacuum pump 103, and the vacuum pump flow rate can be adjusted from 0.1 to 10 L / min.

[0028] The eddy current probe 102 has an inner diameter of 3-5 mm and a pressure resistance range of 0.1-10 MPa, making it suitable for high-voltage insulating gas equipment and improving gas collection speed.

[0029] The low-temperature enrichment unit 104 includes a temperature control system, a semiconductor refrigeration chip, a gas enrichment unit, and a desorption system. The gas enrichment unit is connected to a micro vacuum pump 103, and the semiconductor refrigeration chip is connected to the gas enrichment unit. It can achieve deep cryogenic treatment at -50℃ to concentrate trace decomposition products. The temperature control system is used to control the temperature of the desorption system, which is used to desorb the enriched gas. The temperature control system has an accuracy of ±0.5℃, the desorption system has a heating rate of 5-10℃ / min, and the gas enrichment efficiency is ≥95%.

[0030] The high-efficiency filter 201 uses a PTFE membrane with a pore size of 0.1 μm, which can remove interfering components such as particulate matter. The dryer 202 can remove H2O contained in the gas. The catalytic conversion unit 203 is loaded with a Pt / TiO2 nanocatalyst, which can convert the unstable product HF into detectable F. - ion.

[0031] The micro gas chromatography unit 301 is equipped with a multi-channel micro-packed column and a thermal conductivity detector. Gas desorbed by the desorption system enters the multi-channel micro-packed column and is separated. The separated gases sequentially enter the thermal conductivity detector according to different retention times, and the thermal conductivity detector generates different potential signals, compatible with C4F7N and C5F... 10 For fluorine-containing insulating gases such as O, the detection limit can reach the ppb level.

[0032] Specifically, the multichannel micro-filled column is a silica bonded phase C8 column, a graphitized carbon black column, or a molecular sieve column.

[0033] The infrared spectroscopy unit 302 includes a long-path gas cell and a high-sensitivity infrared spectrometer. The long-path gas cell has three optical paths, which can be switched in three levels according to the optical path requirements. The optical path switching range is 30 meters, 50 meters, and 100 meters. It is connected to the gas path of the micro gas chromatograph to realize the coupling of micro gas chromatography and infrared spectroscopy, and the detection limit can reach the ppb level.

[0034] The shorter the optical path length, the higher the detection limit, which is suitable for detecting high-concentration gases; the longer the optical path length, the lower the detection limit, which is suitable for detecting trace amounts of low-concentration substances.

[0035] like Figure 3 As shown, the detection chamber 4 has a cubic structure and is connected to the gas optical path cell. ZnO nanosheet sensor 401, In2O3 microsphere sensor 402, WO3 nanowire sensor 403, Cu-MoS2 nanosheet sensor 404, and Ni-WS2 nanosheet sensor 405 are arranged in a matrix in the detection chamber 4, which can realize high-sensitivity detection of decomposition products such as CF3CN, CO, and C2F5CN, with a detection limit of up to ppb level.

[0036] Specifically, the In2O3 microsphere sensor 402 mainly detects CO2, H2O, and HF; the WO3 nanowire sensor 403 mainly detects C3F6 and C2F4; the Cu-MoS2 nanosheet sensor 404 mainly detects CF3CN and C2F5CN; the Ni-WS2 nanosheet sensor 405 mainly detects C2N2; and the ZnO nanosheet sensor 401 mainly detects CO, CF4, C2F6, C3F8, and NO2.

[0037] The storage module contains a built-in library of gas chromatography standard curves, infrared spectroscopy standard curves, infrared standard spectra, decomposition product literature, and Gaussian computational simulated spectral database. The analysis module can access https: / / www.spectraplot.com to obtain simulated spectral data. This website primarily compares the simulated infrared spectra with the output infrared spectral data from the infrared spectroscopy detection unit to qualitatively identify the decomposition products based on similarity.

[0038] The analysis module has a built-in intelligent analysis model for decomposition products. The intelligent analysis model can output qualitative and quantitative analysis results of decomposition products using the detection data of the micro gas chromatography unit 301, infrared spectroscopy unit 302 and gas sensor array. It can also identify overheating decomposition products and discharge decomposition products using the decomposition product literature library.

[0039] like Figure 1 As shown, the detection method of the device includes the following steps: 1. Gas collection stage When the test begins, the gas acquisition module 1 is activated, the eddy current probe 102 with a corrosion-resistant PTFE coating is inserted into the gas chamber of the equipment, and the flow rate of the micro vacuum pump 103 is set to the target value. Then, the gas chamber sampling unit 101 and the low-temperature enrichment unit 104 are activated. The gas is transported to the low-temperature enrichment unit 104 through the eddy current probe 102 and the micro vacuum pump 103.

[0040] 2. Gas pretreatment stage The gas pretreatment module 2 is activated. The collected gas is desorbed by the desorption system of the low-temperature enrichment unit 104 and first flows into the high-efficiency filter 201 to remove particulate matter. Then it flows into the dryer 202 to remove H2O. Finally, it flows into the catalytic conversion unit 203 to convert the unstable product HF into detectable F. - ion; 3. Chromatographic separation stage The micro gas chromatography unit 301 is started. The pretreated gas enters the multi-channel micro-packed column configured in the micro gas chromatography unit 301 for separation. After detection by the thermal conductivity detector, the chromatographic data is output and transmitted to the intelligent data processing and control system 5. The gas chromatography standard curve library is called to process the chromatographic data generated by the micro gas chromatography unit 301 and generate qualitative and quantitative analysis results.

[0041] This stage mainly detects C4F7N, CO2, and gas components with a concentration of 50 ppm or higher. After being separated in this stage, the collected gases enter the thermal conductivity detector in sequence according to different retention times. The generated peak height, peak area, retention time, and other data are transmitted to the intelligent data processing and control system 5. The separated gases then enter the infrared spectroscopy unit 302 in sequence.

[0042] 4. Spectral Detection Stage The infrared spectroscopy unit 302 is activated and switched to a suitable optical path. The gas flowing out of the micro gas chromatography unit 301 enters the long optical path gas cell, is detected by a high-sensitivity infrared spectrometer, and outputs infrared spectral data, which is then transmitted to the intelligent data processing and control system 5. The infrared spectral data generated by the infrared spectral unit 302 is qualitatively compared by calling the infrared spectral standard curve library, the infrared standard spectrum library, the Gaussian computational simulation spectral database, and accessing the website https: / / www.spectraplot.com, generating qualitative and quantitative analysis results. This stage primarily detects gaseous components with concentrations below 50 ppm. The collected gases are sequentially introduced into the long-path gas cell according to the peak elution order of the chromatographic separation stage. (1) If the micro gas chromatography unit 301 does not detect any components other than C4F7N and CO2, the optical path is switched to 100 m for infrared spectroscopy detection. If the high-sensitivity infrared spectrometer detects a new absorption peak and does not exceed the detection limit, the generated wavenumber, transmittance or absorbance data are transmitted to the intelligent data processing and control system 5, and the gas enters the gas-sensitive sensor array unit for further detection. If the high-sensitivity infrared spectrometer detects a new absorption peak that exceeds the detection limit, the optical path will be switched to 50 m for re-detection, and the generated wavenumber, transmittance or absorbance data will be transmitted to the intelligent data processing and control system 5. The gas will then enter the gas-sensitive sensor array unit for further detection. Of course, you can also choose any optical path of 30 m, 50 m or 100 m to directly perform the detection, depending on the actual situation.

[0043] (2) If the micro gas chromatography unit 301 detects other components besides C4F7N and CO2, the optical path is first switched to 30 m for infrared spectroscopy detection. If the high-sensitivity infrared spectrometer detects a new absorption peak, the optical path is switched to 50 m for further detection. If the detection result of 50 m optical path is consistent with the detection result of 30 m optical path, the generated wavenumber, transmittance or absorbance data are transmitted to the intelligent data processing and control system 5, and the gas enters the gas-sensitive sensor array unit for further detection. If a new absorption peak appears in the 50 m optical path detection result, the optical path is switched to 100 m for detection, and the generated wavenumber, transmittance or absorbance data are transmitted to the intelligent data processing and control system 5. After the detection is completed, the gas enters the gas-sensitive sensor array unit for further detection.

[0044] When the optical path is switched to 30 m for infrared spectroscopy detection, if the high-sensitivity infrared spectrometer does not detect an absorption peak, the signal is directly fed into the gas sensing array.

[0045] 5. Gas sensor array detection stage Gas flowing out of the long optical path gas cell enters the detection chamber 4, and after being detected by the gas-sensitive sensor array, the concentration data is output and transmitted to the intelligent data processing and control system 5.

[0046] This stage mainly detects CO, trace amounts of H2O, CF4, C2F6, C3F8, C3F6, C2F4, CF3CN, C2F5CN, and NO2. The gas flowing out from the infrared spectroscopy unit 302 enters the detection chamber 4 of the gas sensor array. The gas sensor array responds, outputs the concentration data of the corresponding components, and transmits it to the intelligent data processing and control system 5.

[0047] If the gas sensor array does not detect any new gas data, it means that the result detected in the spectral detection stage is the final result. If the gas sensor array detects new gas data, the new data will be added to the detection results.

[0048] 6. Report Generation Stage The data from steps 3-5 are collected, and the decomposition products are classified by calling the decomposition product literature library to generate a complete gas detection report.

[0049] The decomposition products are divided into two categories: discharge decomposition products and overheating decomposition products. If the characteristics of the product type found by calling the literature database are more consistent with those of discharge decomposition products, it is classified as discharge decomposition products, and the equipment is prompted that there may be a partial discharge fault. If the characteristics of the product type are more consistent with those of overheating decomposition products, it is classified as overheating decomposition products, and the equipment is prompted that there may be a local overheating fault.

[0050] The following is a specific application example.

[0051] Testing process and results: Step 1, Gas Collection: Insert the eddy current probe 102 into the gas chamber of the environmentally friendly 10kV gas distribution transformer, turn on the miniature vacuum pump 103 and the cryogenic enrichment unit 104, and start gas collection at a flow rate of 0.1L / min.

[0052] Step 2, Gas Pretreatment: When the high-efficiency filter 201, dryer 202 and catalytic conversion unit 203 are opened, the collected gas flows out from the desorption system in the low-temperature enrichment unit 104, and after being filtered by the high-efficiency filter 201, dried by the dryer 202 and converted by the catalytic conversion unit 203, it flows into the micro gas chromatography unit 301.

[0053] Step 3, Chromatographic separation: After the gas enters the micro gas chromatography unit 301, it is separated by a multi-channel micro packed column and detected by a thermal conductivity detector. The chromatographic data is then output and transmitted to the intelligent data processing and control system, which calls the gas chromatography standard curve library to process the chromatographic data and obtain the types and contents of decomposition products. Only C4F7N and CO2 were detected at this stage, with C4F7N molar fraction at 9.08% and CO2 molar fraction at 90.91%. Step 4, Spectral Analysis: The gas flowing out of the micro gas chromatography unit 301 enters a 50m long optical path gas cell, is detected by the infrared spectroscopy unit 302, and outputs infrared spectral data. The infrared spectral data is then transmitted to the intelligent data processing and control system 5. The system calls the infrared standard spectrum library, the Gaussian computational simulation spectral database, and accesses the website https: / / www.spectraplot.com to compare the similarity of red light spectra, performs qualitative analysis on the infrared spectral data to obtain the types of decomposition products, and calls the infrared spectral standard curve library for quantitative analysis to obtain the content of decomposition products. During this stage, CF4, C2F6, C3F8, CF3CN, and C2F5CN were detected, with concentrations of 23 ppm, 16 ppm, 11 ppm, 8 ppm, and 5 ppm, respectively.

[0054] Step 5: Gas sensor array detection: Gas flowing out of the long optical path gas cell enters the detection gas chamber 4, is detected by the gas-sensitive sensor array, and outputs concentration data. The concentration data is then transmitted to the intelligent data processing and control system to obtain the types and contents of decomposition products. During this stage, CF4, C2F6, C3F8, CF3CN, and C2F5CN were detected, and the contents of CO, trace H2O, C3F6, and C2F4 were 23 ppm, 16 ppm, 11 ppm, 8 ppm, 5 ppm, 533 ppb, 207 ppb, 74 ppb, and 49 ppb, respectively.

[0055] Step 6: Collect the data from the three parts in Steps 3-5, and analyze the decomposition products by calling the decomposition product literature library. The types of decomposition products are consistent with the characteristics of equipment overheating fault. The gas components include: C4F7N, CO2, CF4, C2F6, C3F8, CF3CN, C2F5CN, CO, H2O, C3F6, and C2F4, with contents of 9.08%, 90.91%, 23 ppm, 16 ppm, 11 ppm, 8 ppm, 5 ppm, 533 ppb, 207 ppb, 74 ppb, and 49 ppb, respectively.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A device for detecting the decomposition products of perfluoroalkyl nitrile insulating gases, characterized in that, It includes a gas acquisition module (1), a gas pretreatment module (2), a multi-technology combined module (3), a detection gas chamber (4), and an intelligent data processing and control system (5); The gas acquisition module (1) includes a device gas chamber sampling unit (101) and a low temperature enrichment unit (104) connected in sequence. The gas pretreatment module (2) includes a filter (201), a dryer (202), and a catalytic conversion unit (203) connected in sequence. The multi-technology module (3) includes a micro gas chromatography unit (301) and an infrared spectroscopy unit (302) connected in sequence. The gas detection chamber (4) is equipped with a gas sensor array, which includes a ZnO nanosheet sensor (401), an In2O3 microsphere sensor (402), a WO3 nanowire sensor (403), a Cu-MoS2 nanosheet sensor (404), and a Ni-WS2 nanosheet sensor (405). The low-temperature enrichment unit (104) is connected to the filter (201), the catalytic conversion unit (203) is connected to the micro gas chromatography unit (301), and the infrared spectroscopy unit (302) is connected to the gas sensor array. The miniature gas chromatography unit (301), infrared spectroscopy unit (302) and gas sensor array are all connected to the intelligent data processing and control system (5); The intelligent data processing and control system (5) includes a storage module and an analysis module. The storage module stores a gas chromatography standard curve library, an infrared spectral standard curve library, an infrared standard spectrum library, a decomposition product literature library, and a Gaussian computational simulation spectral database. The analysis module is used to call the database stored in the storage module to analyze the data output by the micro gas chromatography unit (301), the infrared spectroscopy unit (302) and the gas sensor array; The infrared spectral unit (302) includes a long optical path gas cell and an infrared spectrometer. The long optical path gas cell has three optical paths, which can be switched in three levels according to the optical path requirements. The optical path switching of the long optical path gas cell is achieved by a stepper motor. The optical path switching range is 30m, 50m, and 100m. The long-path gas cell is connected to the micro gas chromatography unit (301).

2. The device for detecting the decomposition products of perfluoroalkyl nitrile in insulating gases according to claim 1, characterized in that, The equipment gas chamber sampling unit (101) includes a miniature vacuum pump (103) and an eddy current probe (102) with a corrosion-resistant PTFE coating; the eddy current probe (102) is used to insert into the equipment gas chamber, and the miniature vacuum pump (103) is used to pump the gas in the equipment gas chamber to the cryogenic enrichment unit (104).

3. The device for detecting the decomposition products of perfluoroalkyl nitrile insulating gases according to claim 1, characterized in that, The low-temperature enrichment unit (104) includes a temperature control system, a semiconductor refrigeration chip, a gas enrichment device, and a desorption system; the semiconductor refrigeration chip is connected to the gas enrichment device to achieve a low temperature of -50°C and concentrate trace decomposition products. The temperature control system is used to control the temperature of the desorption system, which is connected to the filter (201).

4. The device for detecting the decomposition products of perfluoroalkyl nitrile insulating gases according to claim 1, characterized in that, The filter (201) uses a PTFE membrane with micron-sized pores to remove particulate matter; The dryer (202) is used to remove moisture from the gas; Pt / TiO2nanocatalyst supported in a catalytic conversion unit (203) for converting the unstable product HF into detectable F - .

5. The device for detecting the decomposition products of perfluoroalkyl nitrile in insulating gases according to claim 1, characterized in that, The micro gas chromatography unit (301) is equipped with a multi-channel micro-packed column and a thermal conductivity detector, and is compatible with a variety of fluorine-containing insulating gases; The multichannel micro-packed column is one or more of the following: silica bonded phase C8 column, graphitized carbon black column, and molecular sieve column.

6. The device for detecting the decomposition products of perfluoroalkyl nitrile insulating gases according to claim 1, characterized in that, The detection chamber (4) is connected to the long optical path gas cell. ZnO nanosheet sensor (401), In2O3 microsphere sensor (402), WO3 nanowire sensor (403), Cu-MoS2 nanosheet sensor (404), and Ni-WS2 nanosheet sensor (405) are arranged in a matrix in the detection chamber (4) to realize the detection of various decomposition products.

7. The device for detecting the decomposition products of perfluoroalkyl nitrile insulating gases according to claim 1, characterized in that, The analysis module has a built-in intelligent analysis model for decomposition products. The intelligent analysis model for decomposition products uses the chromatographic data output by the micro gas chromatography unit (301) and the gas chromatography standard curve library to obtain qualitative and quantitative analysis results of some decomposition products. The intelligent analysis model for decomposition products uses the infrared spectral data output by the infrared spectral unit (302) and the infrared spectral standard curve library to obtain qualitative and quantitative analysis results of another part of the decomposition products. The intelligent analysis model for decomposition products uses a literature database of decomposition products to identify overheating decomposition products and discharge decomposition products.

8. A detection method based on the detection device for decomposition products of perfluoroalkyl nitrile insulating gases according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1, Gas Collection: Gas is collected by the gas chamber sampling unit (101) and enriched by the low temperature enrichment unit (104); Step 2, Gas Pretreatment: The collected gas flows out from the low temperature enrichment unit (104), is filtered by a filter, dried by a dryer and converted by a catalytic conversion unit, and then flows into the micro gas chromatography unit (301). Step 3, Chromatographic separation: After the gas enters the micro gas chromatography unit (301) for detection, the chromatographic data is output and transmitted to the intelligent data processing and control system (5). The gas chromatography standard curve library is called to process the chromatographic data and obtain the types and contents of the first part of the decomposition products. Step 4, Spectral Analysis: Gas flowing out from the micro gas chromatography unit (301) enters the infrared spectroscopy unit (302), is detected and outputs infrared spectral data, and transmits the infrared spectral data to the intelligent data processing and control system (5), calls the infrared spectral standard curve library, the infrared standard spectrum library, and the Gaussian calculation simulation spectral database, processes the infrared spectral data, and obtains the types and contents of the second part of the decomposition products. Step 5: Gas sensor array detection: Gas flowing out of the long optical path gas cell enters the detection gas chamber (4), is detected by the gas-sensitive sensor array, outputs concentration data, and transmits the concentration data to the intelligent data processing and control system (5) to obtain the types and contents of the third part of the decomposition products; Step 6: Collect the data from the three parts in Steps 3-5, and after calling the decomposition product literature library to classify the decomposition products, generate a complete test report.

9. The detection method according to claim 8, characterized in that, The infrared spectral unit (302) includes a long optical path gas cell and an infrared spectrometer. The long optical path gas cell has three optical paths, which can be switched in three levels according to the optical path requirements. The optical path switching of the long optical path gas cell is achieved by a stepper motor. The optical path switching range is 30m, 50m, and 100m. In step 4, the infrared spectral unit (302) performs detection under the following different conditions:

1. If the micro gas chromatography unit (301) does not detect any components other than C4F7N and CO2, the infrared spectroscopy unit (302) will first switch the optical path to 100 m for infrared spectroscopy detection. If the infrared spectrometer detects a new absorption peak and does not exceed the detection limit, the detection data will be transmitted to the intelligent data processing and control system (5), and the gas will enter the gas-sensitive sensor array unit for further detection. If the infrared spectrometer detects a new absorption peak that exceeds the detection limit, the optical path will be switched to a smaller optical path for re-detection and the detection data will be transmitted to the intelligent data processing and control system (5). The gas will then enter the gas-sensitive sensor array unit for further detection.

2. If the micro gas chromatography unit (301) detects other components besides C4F7N and CO2, the infrared spectroscopy unit (302) will first switch the optical path to 30m to perform infrared spectroscopy detection and obtain the detection results. If the infrared spectrometer detects a new absorption peak, the optical path is switched to 50m to continue detection. If the detection result of 50m optical path is consistent with the detection result of 30m optical path, the detection data is transmitted to the intelligent data processing and control system (5), and the gas enters the gas-sensitive sensor array unit for further detection. If a new absorption peak appears in the 50m optical path detection result, the detection is switched to 100m optical path and the generated detection data is transmitted to the intelligent data processing and control system (5). After the detection is completed, the gas enters the gas-sensitive sensor array unit for further detection.

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