A method and device for gas chromatography pretreatment of transformer insulating oil

Abstract

The present invention belongs to the technical field of power grid equipment detection, and relates to a method and device for pretreatment of transformer insulating oil by gas chromatography, the method comprising the following steps: making a standard curve; testing the volume of the balance gas; sampling, evacuating the sampling tube, connecting the sampling tube, querying the pressure value corresponding to the required volume through the standard curve of step one, and setting it to the value through the pressure regulator; opening the first sampling valve, the balance gas enters the sampling tube, and after reaching the required volume, the electronic three-way valve jumps, the sampling tube is disconnected from the sampling tube, and the excess balance gas is emptied; opening the second sampling valve, the balance gas is injected through the injector. The present invention effectively blocks the oil that may be brought out in the balance gas, on the one hand, reduces the pollution of the original oil brought out to the chromatographic column, prolongs the service life of the chromatographic column, and saves the cost of consumables; on the other hand, it avoids the volume of the balance gas occupied by the original oil brought out, improves the accuracy of the balance gas and the accuracy of the entire analysis result.

Description

Technical Field

[0001] The invention belongs to the technical field of power grid equipment detection, and in particular relates to a method and a device for preprocessing transformer insulating oil by gas chromatography. Background Art

[0002] In the power system, gas chromatography analysis of transformer oil is a common transformer fault diagnosis method. By measuring the characteristic components of gas dissolved in transformer oil, transformer faults can be discovered in advance and countermeasures can be taken. This is also one of the important means to supervise and ensure the safe and stable operation of transformers. Various transformer oil chromatography detection schemes are emerging in an endless stream. The main detection technologies for main transformer oil include laboratory oil chromatography detection, online oil chromatography detection and portable oil chromatography detection. The most authoritative detection method is still laboratory oil chromatography detection.

[0003] However, the current laboratory oil chromatography test has many manual operation steps, which are cumbersome and require high testing from operators. GB / T 7252-2001 Guidelines for Analysis and Judgment of Dissolved Gases in Transformer Oil stipulates that the analysis results of multiple injections of the same gas should be within ±1.5% of its average value (i.e., repeatability within ±1.5%). Therefore, in the gas chromatography test of dissolved gases in transformer insulating oil, the injection step is very critical. The injection volume, injection time, trace oil remaining in the sample, and injection device will affect the test results, thereby further affecting the analysis of the transformer status, which seriously threatens the safe and stable operation of the power system.

[0004] The commonly used sampling method in the laboratory is to use a needle to extract the gas dissolved in the oil, read the volume of the equilibrium gas sample escaping from the fixed oil sample, and insert the equilibrium gas sample into the gas chromatograph injection port through a micro syringe to complete the injection. In the actual operation process, due to the small diameter of the injection port, the volume of the equilibrium gas escaping is small, the operator has to observe and read the steps with the naked eye, and the individual differences in manual operation of the operator often lead to the following problems: 1. The micro syringe is not perpendicular to the injection port seal, and the needle may be damaged. If it is not damaged, part of the sample is not fully injected during the injection. In either case, the injection fails; 2. The carrier gas pressure in the injection port is high, and the carrier gas may enter the micro syringe, causing the sample to change, requiring re-sampling and re-injection. The injection needs to be repeated Taking oil samples for degassing greatly wastes the energy and time of the experimenters, and may damage the needle of the micro-syringe; 3. Manually taking out the balance gas obtained by oscillation from the oil sample syringe may bring out a trace amount of oil. This part of the oil vapor affects the balance gas. At the same time, there is a certain error in the balance gas volume read by the human eye. The balance gas volume is greatly affected by human factors, which affects the subsequent characteristic gas content analysis; in addition, the trace oil brought out in the balance gas enters the gas chromatograph and remains on the chromatographic column, causing chromatographic column contamination, affecting the separation of the balance gas sample, thereby affecting the test results. The life of the contaminated chromatographic column is greatly shortened, and the frequency of replacing the chromatographic column is greatly increased. Some chromatographic columns need to be imported from abroad, resulting in a certain degree of resource waste and economic losses.

[0005] This is a shortcoming of the prior art. Therefore, in view of the above-mentioned defects in the prior art, it is very necessary to provide a method and device for gas chromatography pretreatment of transformer insulating oil. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method and device for gas chromatography pretreatment of transformer insulating oil, which can improve detection efficiency, data accuracy and extend the service life of the chromatographic column, save labor and have strong practicality, and can be linked with existing laboratory degassing and oil chromatography testing devices, thereby overcoming the shortcomings of the prior art.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] The first aspect of the present invention provides a transformer insulating oil gas chromatography pretreatment device, comprising:

[0009] A sampling tube assembly, the sampling tube assembly comprising: a sampling tube and a sampling needle, a filter membrane, a first sampling valve, a first vacuum pump, a flow meter, and a second sampling valve sequentially arranged on the sampling tube, wherein the sampling needle is installed at the first end of the sampling tube;

[0010] The electronic three-way valve has an electronic three-way valve port a, an electronic three-way valve port b, and an electronic three-way valve port c; the electronic three-way valve port a is connected to the second end of the sampling tube;

[0011] The injection tube assembly comprises: an injection tube and a first injection valve, a pressure regulator, a second vacuum pump, a second injection valve, and an injector which are sequentially arranged on the injection tube. The first end of the injection tube is connected to the C port of the electronic three-way valve, and the injector is installed at the second end of the injection tube.

[0012] Furthermore, the injector is an electronic injector.

[0013] Furthermore, the filter membrane is a filter membrane that blocks liquid and only allows gas to pass through.

[0014] The second aspect of the present invention provides a method for pre-treating transformer insulating oil by gas chromatography, comprising the following steps:

[0015] Step 1: Make a standard curve;

[0016] Step 2: Test the balance gas volume;

[0017] Step 3, injection, evacuate the injection tube, connect it to the sampling tube, query the pressure value corresponding to the required volume through the standard curve in step 1, and set it to this value through the pressure regulator; open the first injection valve, and the balance gas enters the injection tube. When the required volume is reached, the electronic three-way valve jumps, the injection tube is disconnected from the sampling tube, and the excess balance gas is emptied; open the second injection valve, and the balance gas is injected through the injector.

[0018] Among them, the steps of step one are:

[0019] 1.1 Connect the electronic three-way valve b port to the N2 gas source, and the electronic three-way valve c port to the sampling tube, open the first sampling valve, close the second sampling valve, turn off the N2 gas source, and evacuate the sampling tube through the second vacuum pump. After evacuation, open the N2 gas source to fill the sampling tube until the pressure regulator measurement value remains unchanged, turn off the gas source, and record the N2 volume used and the pressure displayed by the pressure regulator. This is the maximum volume and corresponding pressure of the sampling tube;

[0020] 1.2 Open the second injection valve to exhaust the gas, and re-evacuate the injection tube to vacuum according to the method in step 1.1. After vacuum, open the N2 gas source and fill the injection tube with a fixed volume of gas. Record the gas volume used at this time and the result of the pressure regulator test at this time;

[0021] 1.3 Repeat step 1.2 to obtain multiple sets of volume and pressure values;

[0022] 1.4 Draw a standard curve using multiple sets of measured data.

[0023] Among them, the steps of step 2 are:

[0024] 2.1 Close the first sampling valve and the second sampling valve, and use the first vacuum pump to evacuate the sampling tube;

[0025] 2.2 The sampling needle connects the oil sample needle tube containing the balance gas to the sampling tube, and the first sampling valve is opened to allow the balance gas to pass through the sampling needle and the filter membrane into the sampling tube;

[0026] 2.3 Observe the flow meter. When the flow meter value remains unchanged, it means that the balance gas has been extracted. Record the value of the flow meter at this time, which is the volume of the balance gas.

[0027] The advantages and positive effects of the present invention are:

[0028] 1. The present invention can accurately test the volume of the balancing gas, improve the accuracy of the dissolved gas content in the oil, and provide accurate support for the fault diagnosis and daily maintenance of the transformer;

[0029] 2. The present invention does not require manual operation throughout the entire process, thus avoiding errors caused by human factors, greatly improving the accuracy of the test, and at the same time, saving labor costs and improving test efficiency;

[0030] 3. The present invention does not require changing the existing gas chromatograph and degassing device in the laboratory, and can be widely promoted on the existing basis, with strong operability and feasibility;

[0031] 4. The present invention effectively blocks the oil that may be brought out in the balance gas. On the one hand, it reduces the pollution of the chromatographic column by the original oil, prolongs the service life of the chromatographic column, and saves the cost of consumables; on the other hand, it avoids the volume of the balance gas occupied by the original oil, improves the accuracy of the balance gas and the accuracy of the entire analysis result. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of the device of the present invention;

[0033] Figure 2 Flow chart of the method of the present invention.

[0034] The above drawings include the following reference numerals:

[0035] 1 is a sampling needle, 2 is a sampling tube, 3 is a filter membrane, 4 is a first sampling valve, 5 is a first vacuum pump, 6 is a flow meter, 7 is a second sampling valve, 8 is an electronic three-way valve, 9 is a port a of the electronic three-way valve, 10 is a port b of the electronic three-way valve, 11 is a port c of the electronic three-way valve, 12 is an injection tube, 13 is a first injection valve, 14 is a pressure regulator, 15 is a second vacuum pump, 16 is a second injection valve, and 17 is an injector. DETAILED DESCRIPTION

[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0038] Figure 1 This is a schematic diagram of the device of the present invention, as shown in the figure, which includes: a sampling tube assembly and a sampling tube assembly.

[0039] The sampling tube assembly is composed of a sampling tube 2 and other components installed on the sampling tube 2;

[0040] The sampling tube 2 is equipped with a sampling needle 1, a filter membrane 3, a first sampling valve 4, a first vacuum pump 5, a flow meter 6, and a second sampling valve 7;

[0041] The sample injection tube assembly is composed of a sample injection tube 12 and other components in the sample injection tube 12;

[0042] The injection tube 12 is equipped with a first injection valve 13, a pressure regulator 14, a second vacuum pump 15, a second injection valve 16, and an injector 17;

[0043] The sampling tube assembly is connected to the sampling tube assembly via an electronic three-way valve 8 , and the electronic three-way valve 8 comprises an electronic three-way valve a port 9 , an electronic three-way valve b port 10 , and an electronic three-way valve c port 11 .

[0044] The sampling needle 1 is a double-ended needle, one end of which is connected to the syringe that outputs the balance gas, and the other end is connected to the sampling tube 2;

[0045] The sampling tube 12 is connected to the sampling tube 2 via an electronic three-way valve 8;

[0046] The pressure regulator 14 can measure the pressure value and set the pressure value;

[0047] The injector 17 is an electronic injector, which can provide assistance for the sample gas to enter the detector;

[0048] The filter membrane 3 is a filter membrane that blocks liquid and only allows gas to pass through; the filter membrane 3 can be flexibly replaced.

[0049] Figure 2 The flowchart of the method of the present invention comprises the following steps:

[0050] Step 1: Create a standard curve

[0051] 1.1 Connect the electronic three-way valve b port 10 to the N2 gas source, connect the electronic three-way valve c port 11 to the sampling tube 12, open the first sampling valve 13, close the second sampling valve 16, turn off the N2 gas source, and evacuate the sampling tube 12 through the second vacuum pump 15. After evacuation, open the N2 gas source to fill the sampling tube 12 until the pressure regulator 14 measures the value unchanged, turn off the gas source, and record the N2 volume used and the pressure displayed by the pressure regulator 14. This is the maximum volume and corresponding pressure of the sampling tube 12;

[0052] 1.2 Open the second injection valve 16 to exhaust the gas, and evacuate the injection tube 12 again according to the method in step 1.1. After the vacuum is reached, turn on the N2 gas source and fill the injection tube 12 with a fixed volume of gas. Record the gas volume used at this time and the test result of the pressure regulator 14 at this time;

[0053] 1.3 Repeat step 1.2 to obtain multiple sets of volume and pressure values;

[0054] 1.4 Draw a standard curve using multiple sets of measured data.

[0055] Step 2: Test the balance gas volume

[0056] 2.1 Close the first sampling valve 4 and the second sampling valve 7, and evacuate the sampling tube 2 by the first vacuum pump 5;

[0057] 2.2 The sampling needle 1 connects the oil sample needle tube containing the balance gas to the sampling tube 2, and the first sampling valve 4 is opened to allow the balance gas to pass through the sampling needle 1 and the filter membrane 3 into the sampling tube 2;

[0058] 2.3 Observe the flow meter 6. When the value of the flow meter 6 remains unchanged, it means that the balance gas has been extracted. Record the value of the flow meter 6 at this time, which is the volume of the balance gas.

[0059] Step 3: Sample injection

[0060] 3.1 According to the method in step 1.1, the sampling tube 12 is evacuated and connected to the sampling tube 2 through the electronic three-way valve 8, the electronic three-way valve a port 9 is connected to the sampling tube 2, and the electronic three-way valve c port 11 is connected to the sampling tube 12;

[0061] 3.2 Query the pressure value corresponding to the required volume through the standard curve in step 1, and set it to this value through the pressure regulator 14;

[0062] 3.3 Open the first injection valve 13, and the balance gas enters the injection tube 12. When the required volume is reached, the electronic three-way valve 8 jumps, the injection tube 12 is disconnected from the sampling tube 2, and the excess balance gas is emptied;

[0063] 3.4 Open the second injection valve 16, and the balance gas is injected through the injector 17.

[0064] The present invention effectively blocks the oil that may be brought out in the balance gas, which, on the one hand, reduces the pollution of the chromatographic column by the original oil brought out, prolongs the service life of the chromatographic column, and saves the cost of consumables; on the other hand, it avoids the volume of the balance gas occupied by the original oil brought out, improves the accuracy of the balance gas and the accuracy of the entire analysis result.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for pretreatment of transformer insulating oil by gas chromatography, characterized in that: The steps include: Step 1: Make a standard curve; Step 2: Test the balance gas volume; Step 3, injection, the injection tube (12) is evacuated and connected to the sampling tube (2), the pressure value corresponding to the required volume is queried through the standard curve in step 1, and the pressure value is set to the pressure value through the pressure regulator (14); the first injection valve (13) is opened, and the balance gas enters the injection tube (12). After reaching the required volume, the electronic three-way valve (8) jumps, the injection tube (12) is disconnected from the sampling tube (2), and the excess balance gas is emptied; the second injection valve (16) is opened, and the balance gas is injected through the injector (17); The specific steps of step one are: 1.1 Connect the electronic three-way valve b port (10) to the N2 gas source, connect the electronic three-way valve c port (11) to the sampling tube (12), open the first sampling valve (13), close the second sampling valve (16), turn off the N2 gas source, and evacuate the sampling tube (12) through the second vacuum pump (15). After the vacuum is reached, open the N2 gas source to fill the sampling tube (12) until the measured value of the pressure regulator (14) remains unchanged, turn off the gas source, and record the N2 volume used and the pressure displayed by the pressure regulator (14). This is the maximum volume and corresponding pressure of the sampling tube (12); 1.2 Open the second injection valve (16) to exhaust the gas, and evacuate the injection tube (12) again according to the method in step 1.

1. After the vacuum is reached, open the N2 gas source and fill the injection tube (12) with a fixed volume of gas. Record the gas volume used at this time and the test result of the pressure regulator (14) at this time; 1.3 Repeat step 1.2 to obtain multiple sets of volume and pressure values; 1.4 Draw a standard curve based on the measured data; The specific steps of step 2 are: 2.1 Close the first sampling valve (4) and the second sampling valve (7), and evacuate the sampling tube (2) using the first vacuum pump (5); 2.2 The sampling needle (1) is connected to the oil sample needle tube containing the balance gas and the sampling tube (2), and the first sampling valve (4) is opened so that the balance gas passes through the sampling needle (1) and the filter membrane (3) into the sampling tube (2); 2.3 Observe the flow meter (6). When the value of the flow meter (6) remains unchanged, it means that the balance gas has been extracted. Record the value of the flow meter (6) at this time, which is the volume of the balance gas.

2. A device for implementing the method according to claim 1, characterized in that: include: A sampling tube assembly, the sampling tube assembly comprising: a sampling tube (2) and a sampling needle (1), a filter membrane (3), a first sampling valve (4), a first vacuum pump (5), a flow meter (6), and a second sampling valve (7) which are sequentially arranged on the sampling tube (2), the sampling needle (1) being installed at a first end of the sampling tube (2); The electronic three-way valve (8) comprises an electronic three-way valve port a (9), an electronic three-way valve port b (10), and an electronic three-way valve port c (11); the electronic three-way valve port a (9) is connected to the second end of the sampling tube (2); An injection tube assembly, the injection tube assembly comprising: an injection tube (12) and a first injection valve (13), a pressure regulator (14), a second vacuum pump (15), a second injection valve (16), and an injector (17) which are sequentially arranged on the injection tube (12), wherein the first end of the injection tube (12) is connected to the C port (11) of the electronic three-way valve, and the injector (17) is installed at the second end of the injection tube (12).

3. The device according to claim 2, characterized in that The sample injector (17) is an electronic sample injector.

4. The device according to claim 2, characterized in that The filter membrane (3) is a filter membrane that blocks liquid and only allows gas to pass through.

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