Insulating gas perfluoroalkyl nitrile decomposition product detection device and method

Abstract

The invention belongs to the technical field of gas detection, and particularly relates to a device and a method for detecting decomposition products of insulating gas perfluoroalkyl nitrile. The device comprises a gas collection module, a pretreatment module, a multi-technology combination module, a detection gas chamber and an intelligent data processing and control system, wherein the gas collection module collects and concentrates a gas sample through an equipment gas chamber sampling unit and a low-temperature enrichment unit; the pretreatment module purifies gas and converts complex components through a high-efficiency filter, a dryer and a catalytic conversion unit; the multi-technology combination module is used for separating gas by using a micro gas chromatography unit and carrying out qualitative analysis by using an infrared spectrum unit; a gas sensitive sensor array of the detection gas chamber realizes multi-dimensional detection; a storage module of the intelligent data processing and control system stores various databases, an analysis module calls the databases to analyze multi-module data, and sampling, detection and intelligent analysis of decomposition products are achieved. The problems that existing detection has a leak detection condition and lacks pertinence and high efficiency are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas detection, and in particular relates to a device and method for detecting decomposition products of perfluoroalkyl nitrile as an insulating gas. Background Art

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

[0003] Currently, the detection of perfluoroalkyl nitriles and their decomposition products primarily relies on gas chromatography and mass spectrometry. These instruments are expensive, bulky, and require complex sample pretreatment and vacuum environment maintenance, making them unsuitable for rapid on-site testing and difficult to ensure both comprehensiveness and accuracy. Furthermore, existing qualitative analysis techniques primarily rely on existing standard gases, which often lacks specificity and efficiency in detecting perfluoroalkyl nitrile decomposition products. This can lead to difficulties in qualitatively identifying some decomposition products and missed detections due to poor chromatographic column separation, making it difficult to meet the urgent needs of on-site electrical equipment maintenance. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and method for detecting decomposition products of perfluoroalkyl nitrile in insulating gas, which solves the problems of missed detection, lack of pertinence and high efficiency in existing detection.

[0005] The present invention is achieved through the following technical solutions: The present invention discloses a device for detecting decomposition products of perfluoroalkyl nitrile of insulating gas, comprising a gas collection module, a gas pretreatment module, a multi-technology combination module, a detection gas chamber, and an intelligent data processing and control system; The gas collection module includes an equipment 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-technique coupling module includes a micro gas chromatography unit and an infrared spectroscopy unit connected in sequence; A gas sensor array is provided in the detection gas chamber, 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 the high-efficiency filter, the catalytic conversion unit is connected to the micro gas chromatography unit, and the infrared spectrum unit is connected to the gas sensor array; The micro 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 spectrum standard curve library, an infrared standard spectrum library, a decomposition product literature library, and a Gaussian calculation simulation spectrum 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, the infrared spectrum unit and the gas sensor array.

[0006] Furthermore, the equipment air 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 be inserted into the equipment air chamber, and is used to pump the gas in the equipment air chamber into the low-temperature enrichment unit through the miniature vacuum pump.

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

[0008] Furthermore, the HEPA filter uses a PTFE membrane with a micron-sized pore size to remove interfering components such as particulate matter; The dryer is used to remove moisture from the gas; The Pt / TiO2 nanocatalyst is loaded in the catalytic conversion unit to convert the unstable product HF into detectable F - ion.

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

[0010] Furthermore, the infrared spectroscopy unit includes a long optical path gas cell and an infrared spectrometer. The long optical path gas cell is divided into three optical paths and can be switched into three gears according to the optical path requirements. The optical path switching of the long optical path gas cell is driven by a stepper motor. The optical path switching range is 30m, 50m, and 100m. The long pathlength 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 form 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, which 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 decomposition product intelligent analysis model uses the infrared spectrum data output by the infrared spectrum unit and the infrared spectrum standard curve library to obtain qualitative and quantitative analysis results of another part of the decomposition products; The decomposition product intelligent analysis model utilizes a decomposition product library to identify overheating decomposition products and discharge decomposition products.

[0013] The present invention also discloses a detection method based on the insulating gas perfluoroalkyl nitrile decomposition product detection device, comprising the following steps: Step 1: Gas collection: The gas is collected through the equipment's gas chamber sampling unit, and the low-temperature enrichment unit enriches the gas; 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, and then flows into the micro gas chromatography unit; Step 3, chromatographic separation: After the gas enters the micro gas chromatography unit for detection, the chromatographic data is output and transmitted to the intelligent data processing and control system. The chromatographic data is processed by calling the gas chromatography standard curve library to obtain the type and content of the first part of the decomposition product; Step 4: Spectral analysis: The gas flowing out of the micro gas chromatography unit enters the infrared spectrum unit, which outputs infrared spectrum data after detection and transmits the infrared spectrum data to the intelligent data processing and control system. The infrared spectrum standard curve library, infrared standard spectrum library, and Gaussian calculation simulation spectrum database are called to process the infrared spectrum data to obtain the type and content of the second part of the decomposition product; Step 5: Gas sensor array detection: The gas flowing out of the long optical path gas cell enters the detection gas chamber, is detected by the gas sensor array, and then outputs the concentration data. The concentration data is then transmitted to the intelligent data processing and control system to obtain the type and content of the third part of the decomposition product; Step 6: Gather the data from the three parts in Step 3 to Step 5, call the decomposition product literature library to classify the decomposition products, and then generate a complete test report.

[0014] Furthermore, the infrared spectroscopy unit includes a long optical path gas cell and an infrared spectrometer. The long optical path gas cell is divided into three optical paths and can be switched into three gears according to the optical path requirements. The optical path switching of the long optical path gas cell is driven by a stepper motor. The optical path switching range is 30m, 50m, and 100m. In step 4, the infrared spectrum unit detection is divided into the following different situations: First, if the micro gas chromatography unit does not detect other components except C4F7N and CO2, the infrared spectrum unit will first switch the optical path to 100 m for infrared spectrum 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 and exceeds the upper detection limit, the optical path is switched to a smaller range for re-detection and 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; Second, if the micro gas chromatography unit detects other components besides C4F7N and CO2, the infrared spectrum unit will first switch the optical path to 30 m to perform infrared spectrum detection and obtain the test 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 the 50m optical path is consistent with that of the 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 the 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 present invention aims to provide a device for detecting perfluoroalkyl nitrile decomposition products in insulating gas, comprising a gas collection module comprising an equipment gas chamber sampling unit and a low-temperature enrichment unit. The equipment gas chamber sampling unit directly collects gas samples containing perfluoroalkyl nitrile decomposition products from the equipment under test, preventing gas component escape or interference from external impurities during the sampling process. The low-temperature enrichment unit uses cryogenic condensation technology to enrich low-concentration decomposition products in the sampled gas, improving subsequent detection sensitivity. The low-temperature selective retention of target components allows for preliminary separation of water vapor and high-boiling-point impurities, reducing the burden on the pretreatment module.

[0016] The gas pretreatment module uses a high-efficiency filter to filter out solid particles, oil stains and other mechanical impurities in the gas to prevent blockage of subsequent pipelines or contamination of detection elements, ensuring gas cleanliness; a dryer is used to remove moisture from the gas to prevent water vapor from interfering with the gas chromatography separation efficiency, infrared spectrum absorption signal or gas sensor performance; and a catalytic conversion unit is used to convert the complex decomposition products of perfluoroalkyl nitrile into small molecular substances that are easy to detect.

[0017] The multi-technique module includes a gas chromatography unit and an infrared spectroscopy unit. The micro gas chromatography unit utilizes the differences in the adsorption / desorption capacity of the chromatographic column for different gas components to achieve efficient separation of decomposition products. By comparing with the gas chromatography standard curve library, the concentration of each component is calculated, providing accurate quantitative data. The infrared spectroscopy unit detects the characteristic absorption spectrum of gas molecules to infrared light and compares it with the infrared standard spectrum library to identify the chemical structure of the decomposition products. In combination with the infrared spectrum standard curve library, the absorbance of characteristic functional groups is analyzed to assist gas chromatography in the quantification of complex components.

[0018] A gas sensor array is provided in the detection chamber, which uses different types of sensors to supplement the detection of a variety of fluorine-containing gases. The coordinated response of multiple sensors improves the recognition accuracy and anti-interference ability of complex gas components.

[0019] The gas sensor array's detection results are complemented and cross-validated with data from the micro-GC and infrared spectroscopy units through an intelligent data processing and control system, improving detection accuracy. During testing, gas flows first into the micro-GC, then into the infrared spectroscopy unit, and finally into the gas sensor array. This complementary and cross-validated approach across multiple detection technologies enhances both the quantitative accuracy and qualitative comprehensiveness of perfluoroalkyl nitrile decomposition product detection. Built-in databases improve the efficiency and convenience of qualitative and quantitative analysis of decomposition products, and enable the diagnosis of discharge or overheating faults in high-voltage gas-insulated equipment.

[0020] Furthermore, because the concentration of decomposition products cannot be predicted in advance during on-site operation and maintenance, this design is to meet the detection needs of decomposition products with the same concentration under different equipment failures, avoiding the problem of mismatch between range and concentration during single optical path detection. The infrared spectrum unit of the present invention is divided into different situations during detection: First, if the micro gas chromatography unit does not detect other components besides C4F7N and CO2, the infrared spectrum unit will first switch the optical path to 100 m for infrared spectrum detection. If the infrared spectrometer detects a new absorption peak and does not exceed the upper detection limit, it means that the range is appropriate and there is no need to select a smaller range for detection. 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 as a supplementary detection; If the infrared spectrometer detects a new absorption peak that exceeds the upper detection limit, it means that the 100m range is too large. Although qualitative analysis is still possible, quantitative analysis will be inaccurate. Therefore, the optical path must be switched to 50m for accurate quantitative analysis. The optical path is then switched to 50m for re-testing and the test data is transmitted to the intelligent data processing and control system. The gas enters the gas sensitive sensor array unit for further testing as a supplementary test. 2. If the micro gas chromatography unit detects components other than C4F7N and CO2, it means that the concentrations of most components may be within the detectable range of the 30-m optical path. The infrared spectrum unit will prioritize switching the optical path to 30 m for infrared spectrum detection. If the infrared spectrometer detects a new absorption peak, it means that there is a possibility that lower concentration components may be missed at the 30-m optical path. The optical path will be switched to 50 m for further detection. If the detection results of the 50-m optical path are consistent with those of the 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 the 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure: 1. Gas collection module; 2. Gas pretreatment module; 3. Multi-technology combination module; 4. Gas detection chamber; 5. Intelligent data processing and control system; 101. Equipment gas chamber sampling unit; 102. Eddy current probe; 103. Micro vacuum pump; 104. Low-temperature enrichment unit; 201. High-efficiency filter; 202. Dryer; 203. Catalytic conversion unit; 301. Micro 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 DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following is a further detailed description with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

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

[0025] like Figure 2 As shown, the present invention discloses a device for detecting decomposition products of perfluoroalkyl nitrile of insulating gas, comprising: Gas collection module 1, including equipment gas chamber sampling unit 101 and low temperature enrichment unit 104; Gas pre-treatment module 2, including a high efficiency filter 201, a dryer 202 and a catalytic conversion unit 203; Multi-technology module 3, including micro gas chromatography unit 301 and infrared spectroscopy unit 302; Detection chamber 4, in which a gas sensor array is arranged, 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 air chamber sampling unit 101 adopts a corrosion-resistant PTFE-coated eddy current probe 102, which can be directly inserted into the equipment air chamber, and has a built-in micro vacuum pump 103, and the vacuum pump flow adjustment range is 0.1-10 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, and is suitable for high-voltage insulating gas equipment; it improves the gas collection speed.

[0029] The low-temperature enrichment unit 104 includes a temperature control system, a semiconductor refrigeration plate, a gas enricher and a desorption system. The gas enricher is connected to the micro vacuum pump 103, and the semiconductor refrigeration plate is connected to the gas enricher, which can achieve deep cooling at -50°C and concentrate trace decomposition products. The temperature control system is used to control the temperature of the desorption system, and the desorption system is used to desorb the enriched gas. The temperature control system has an accuracy of ±0.5°C, the desorption system heating rate is 5-10°C / 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 to 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 Pt / TiO2 nanocatalyst to convert the unstable product HF into detectable F - ion.

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

[0032] Specifically, the multi-channel micro-filling column adopts a silica gel bonded phase C8 column, a graphitized carbon black column or a molecular sieve column.

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

[0034] The smaller the optical path, the higher the detection limit, which is suitable for detecting gases with high concentrations; the larger the optical path, 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 is a cube structure, which is connected to the gas optical path cell. The ZnO nanosheet sensor 401, the In2O3 microsphere sensor 402, the WO3 nanowire sensor 403, the Cu-MoS2 nanosheet sensor 404, and the Ni-WS2 nanosheet sensor 405 are arranged in the detection chamber 4 in a matrix form, which can achieve high-sensitivity detection of decomposition products such as CF3CN, CO, and C2F5CN, and the detection limit can reach 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 spectrum libraries, a decomposition product literature library, and a Gaussian computational simulation spectrum database. The analysis module can access the website https: / / www.spectraplot.com to obtain simulated spectral data. This website primarily compares simulated infrared spectra with the infrared spectral data output by the infrared spectroscopy detection unit to determine the decomposition product identity based on similarity.

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

[0039] like Figure 1 As shown, the detection method of the device includes the following steps: 1. Gas collection stage When starting the test, start the gas collection module 1, insert the eddy current probe 102 with corrosion-resistant PTFE coating into the equipment air chamber and set the flow of the micro vacuum pump 103 to the target value, then start the equipment air chamber sampling unit 101 and the low-temperature enrichment unit 104; 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 Start the gas pretreatment module 2. 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 flows into the dryer 202 to remove H2O, and finally 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, and the pretreated gas enters the multi-channel micro-filled 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 to generate qualitative and quantitative analysis results.

[0041] This stage mainly detects C4F7N, CO2 and gas components with a concentration above 50 ppm. The collected gas is separated in this stage and enters the thermal conductivity detector in sequence with 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 gas enters the infrared spectrum unit 302 in sequence.

[0042] 4. Spectral detection stage The infrared spectroscopy unit 302 is activated and switched to an appropriate optical path. The gas flowing out of the micro gas chromatography unit 301 enters the long optical path gas cell. After detection by a high-sensitivity infrared spectrometer, the infrared spectral data is output and transmitted to the intelligent data processing and control system 5. The infrared spectroscopy standard curve library, infrared standard spectrum library, Gaussian computational simulation spectrum database, and the website https: / / www.spectraplot.com are accessed to perform a qualitative comparison of the infrared spectral data generated by the infrared spectroscopy unit 302 to generate qualitative and quantitative analysis results. This stage mainly detects gas components with concentrations below 50 ppm. The collected gases enter the long optical path gas cell in the order of peaks in the chromatographic separation stage: (1) If the micro gas chromatography unit 301 does not detect other components except C4F7N and CO2, the optical path is first switched to 100 m for infrared spectrum detection. If the high-sensitivity infrared spectrometer detects a new absorption peak and does not exceed the detection limit, the generated wave number, 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 and exceeds the upper detection limit, the optical path is switched to 50 m for re-detection and the generated wave number, transmittance or absorbance and other data are transmitted to the intelligent data processing and control system 5, and the gas enters the gas sensing array unit for further detection; Of course, you can also choose any one of the 30m, 50m or 100m optical paths for direct detection according to actual conditions.

[0043] (2) If the micro gas chromatography unit 301 detects other components except C4F7N and CO2, the optical path is first switched to 30 m for infrared spectrum 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 the 50 m optical path is consistent with the detection result of the 30 m optical path, the generated wave number, transmittance or absorbance and other 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 wave number, transmittance or absorbance and other 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 spectrum detection, if the high-sensitivity infrared spectrometer does not detect an absorption peak, it directly enters the gas sensing array.

[0045] 5. Gas sensor array detection stage The gas flowing out of the long optical path gas cell enters the detection gas chamber 4 , is detected by the gas sensor array, and then outputs the concentration data and transmits it to the intelligent data processing and control system 5 .

[0046] This stage mainly detects CO, trace H2O, CF4, C2F6, C3F8, C3F6, C2F4, CF3CN, C2F5CN, and NO2. The gas flowing out of the infrared spectrum unit 302 enters the detection gas 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 new gas data, it means that the result of the spectrum 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 Gather the data from the three parts in step 3 to step 5, classify the decomposition products by calling the decomposition product literature library, and generate a complete gas detection report.

[0049] Decomposition products are divided into two categories: one is discharge decomposition products, and the other is overheating decomposition products. If the literature library is called and it is found that the product type characteristics are more consistent with discharge decomposition products, it is classified as a discharge decomposition product, and it is indicated that the equipment may have a local discharge fault. If the product type characteristics are more consistent with overheating decomposition products, it is classified as an overheating decomposition product and it is indicated that the equipment may have a local overheating fault.

[0050] The following introduces a specific application example.

[0051] Testing process and results: Step 1: Gas collection: The eddy current probe 102 was inserted into the gas chamber of an environmentally friendly 10 kV gas distribution transformer, the micro vacuum pump 103 and the low-temperature enrichment unit 104 were turned on, and gas collection was started at a flow rate of 0.1 L / min.

[0052] Step 2: Gas pretreatment: The high-efficiency filter 201, the dryer 202 and the catalytic converter unit 203 are turned on, and the collected gas flows out from the desorption system in the low-temperature enrichment unit 104, is filtered by the high-efficiency filter 201, dried by the dryer 202 and converted by the catalytic converter unit 203, and then 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-filled column and detected by a thermal conductivity detector. The chromatographic data is output and transmitted to the intelligent data processing and control system. The chromatographic data is processed by calling the gas chromatography standard curve library to obtain the type and content of the decomposition products. Only C4F7N and CO2 were detected at this stage, with the mole fraction of C4F7N being 9.08% and the mole fraction of CO2 being 90.91%; Step 4: Spectral analysis: The gas flowing out of the micro gas chromatography unit 301 enters the 50 m long optical path gas cell, is detected by the infrared spectrum unit 302, and then outputs infrared spectrum data. The infrared spectrum data is transmitted to the intelligent data processing and control system 5. The infrared standard spectrum library, the Gaussian computational simulation spectrum database, and the website https: / / www.spectraplot.com are accessed to compare the red light spectrum similarity, and the infrared spectrum data is qualitatively analyzed to obtain the type of decomposition product. The infrared spectrum standard curve library is used for quantitative analysis to obtain the content of the decomposition product. During this stage, CF4, C2F6, C3F8, CF3CN, and C2F5CN were detected, with contents of 23 ppm, 16 ppm, 11 ppm, 8 ppm, and 5 ppm, respectively.

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

[0055] Step 6. Gather the data from the three parts in Step 3-Step 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 failure. The gas components include: C4F7N, CO2, CF4, C2F6, C3F8, CF3CN, C2F5CN, CO, H2O, C3F6, 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, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A device for detecting decomposition products of perfluoroalkyl nitrile of insulating gas, characterized in that: It includes a gas collection module (1), a gas pre-processing module (2), a multi-technology combination module (3), a detection gas chamber (4), and an intelligent data processing and control system (5); The gas collection module (1) comprises an equipment gas chamber sampling unit (101) and a low-temperature enrichment unit (104) connected in sequence; The gas pre-treatment module (2) comprises a high efficiency filter (201), a dryer (202) and a catalytic conversion unit (203) which are connected in sequence; The multi-technology coupling module (3) includes a micro gas chromatography unit (301) and an infrared spectroscopy unit (302) connected in sequence; A gas sensor array is provided in the detection gas chamber (4), and the gas sensor array 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 high-efficiency filter (201), the catalytic conversion unit (203) is connected to the micro gas chromatography unit (301), and the infrared spectrum unit (302) is connected to the gas sensor array; The micro gas chromatography unit (301), the infrared spectrum unit (302) and the 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, wherein the storage module stores a gas chromatography standard curve library, an infrared spectrum standard curve library, an infrared standard spectrum library, a decomposition product literature library, and a Gaussian calculation simulation spectrum 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 spectrum unit (302) and the gas sensor array.

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

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

4. The device for detecting decomposition products of perfluoroalkyl nitrile in insulating gas according to claim 1, characterized in that: The high efficiency filter (201) uses a PTFE membrane with a micron-sized pore size to remove interfering components such as particulate matter; The dryer (202) is used to remove moisture contained in the gas; The Pt / TiO2 nanocatalyst is loaded in the catalytic conversion unit (203) to convert the unstable product HF into detectable F - ion.

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

6. The device for detecting decomposition products of perfluoroalkyl nitrile in insulating gas according to claim 1, characterized in that: The infrared spectrum unit (302) comprises a long optical path gas cell and an infrared spectrometer. The long optical path gas cell is divided into three optical paths and is switched into three gears according to optical path requirements. The optical path switching of the long optical path gas cell is achieved by driving a stepper motor. The optical path switching range is 30m, 50m, and 100m. The long optical path gas cell is connected to the micro gas chromatography unit (301).

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

8. The device for detecting decomposition products of perfluoroalkyl nitrile in insulating gas according to claim 1, characterized in that: The analysis module has a built-in intelligent analysis model for decomposition products, which 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 decomposition product intelligent analysis model uses the infrared spectrum data output by the infrared spectrum unit (302) and the infrared spectrum standard curve library to obtain qualitative and quantitative analysis results of another part of the decomposition products; The decomposition product intelligent analysis model utilizes a decomposition product library to identify overheating decomposition products and discharge decomposition products.

9. A detection method based on the device for detecting decomposition products of perfluoroalkyl nitrile in insulating gas according to claims 1-8, characterized in that: The following steps are involved: Step 1: Gas collection: The gas is collected by the gas chamber sampling unit (101) of the equipment, and the low-temperature enrichment unit (104) enriches the gas; Step 2: Gas pretreatment: The collected gas flows out from the low-temperature enrichment unit (104), is filtered by a high-efficiency 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: The gas enters the micro gas chromatography unit (301) for detection and outputs chromatographic data, which is then transmitted to the intelligent data processing and control system (5). The chromatographic data is processed by calling the gas chromatography standard curve library to obtain the type and content of the first part of the decomposition product; Step 4: Spectral analysis: The gas flowing out of the micro gas chromatography unit (301) enters the infrared spectrum unit (302), which outputs infrared spectrum data after detection, and transmits the infrared spectrum data to the intelligent data processing and control system (5), which calls the infrared spectrum standard curve library, the infrared standard spectrum library, and the Gaussian calculation simulation spectrum database to process the infrared spectrum data and obtain the type and content of the second part of the decomposition product; Step 5: Gas sensor array detection: The gas flowing out of the long optical path gas cell enters the detection gas chamber (4), is detected by the gas sensor array, and then outputs concentration data, which is then transmitted to the intelligent data processing and control system (5) to obtain the type and content of the third part of the decomposition product; Step 6: Gather the data from the three parts in Step 3 to Step 5, call the decomposition product literature library to classify the decomposition products, and then generate a complete test report.

10. The detection method according to claim 9, characterized in that: The infrared spectrum unit (302) comprises a long optical path gas cell and an infrared spectrometer. The long optical path gas cell is divided into three optical paths and is switched into three gears according to optical path requirements. The optical path switching of the long optical path gas cell is achieved by driving a stepper motor. The optical path switching range is 30m, 50m, and 100m. In step 4, the infrared spectrum unit (302) detects the following different situations:

1. If the micro gas chromatography unit (301) does not detect any components other than C4F7N and CO2, the infrared spectrum unit (302) first switches the optical path to 100 m to perform infrared spectrum detection. If the infrared spectrometer detects a new absorption peak and does not exceed the detection limit, 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 the infrared spectrometer detects a new absorption peak and exceeds the upper detection limit, the optical path is switched to a smaller range for re-detection and 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; 2. If the micro gas chromatography unit (301) detects other components except C4F7N and CO2, the infrared spectrum unit (302) first switches the optical path length to 30 m to perform infrared spectrum detection and obtain the detection results; If the infrared spectrometer detects a new absorption peak, the optical path is switched to 50 m to continue detection. If the detection result of the 50 m optical path is consistent with the detection result of the 30 m 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 the 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.

Images