CN101221127B - Concurrent measuring method for multiple metallic elements in transformer oil - Google Patents

Abstract

The invention relates to a method for simultaneously determining various metal elements in transformer oil. An analyzing sample of the transformer oil of the invention is weighed quantificationally after a collected oil sample is heated and stirred uniformly; an infrared heating method is adopted for carrying out vaporizing and carbonizing at constant temperature on the analyzing sample of the quantificational transformer oil, a box type high temperature furnace is adopted for carrying out high temperature cineration on the carbonized sample, acid liquid is adopted for carrying out dissolvingon the incinerated sample under the lower temperature heating condition, a soluzione leggermente acida is adopted for carrying out diluting and volume fixing on the dissolved sample to be prepared into analyzing liquid. The analyzing liquid accurately determines the content of various metal elements by using a complete spectrum direct reading plasma emission spectrum apparatus. The method of the invention can determine a plurality of elements and has high accuracy, can determine oil mediums with different varieties and content ranges, being capable of accurately showing the change current of the metals in the oil mediums and being convenient for accurately analyzing and finding out hidden troubles in time.

Description

A Simultaneous Determination Method of Multiple Metal Elements in Transformer Oil

technical field

The patent of the present invention relates to a simultaneous determination method of various metal elements in transformer oil.

technical background

In recent years, in order to meet the development needs of the national economy, the country has increased investment in the power industry, and more and more large-capacity units have been put into operation one after another. With the construction of a large power grid, the safety of the power grid has an increasing impact on society. Among the many factors that affect the safety of the power grid, the operation failures and accidents of power equipment caused by the existence of excessive metal impurities in oil have become more and more important in recent years. Happens from time to time everywhere. However, the problems caused by metallic impurities in oil are not well understood. The research on the faults caused by metal impurities and the analysis methods of metal impurities in oil has attracted more and more attention of researchers at home and abroad. However, at present, there is neither a national standard method nor a corresponding industry analysis method for the detection of metal impurities in transformer oil, resulting in low efficiency and high cost of accident analysis, and it is impossible to safely and effectively supervise the operation of equipment.

Conventional chromatographic analysis results can show whether overheating and discharge faults have occurred in the transformer, but it is impossible to determine where the fault occurred or in the circuit. If the analysis data of metal elements is added at this time, combined with electrical indicators, it can be accurately judged what material There is a problem with the components and what kind of failure has occurred, which greatly reduces the difficulty of maintenance, saves maintenance time, and saves maintenance costs. At present, failures and accidents caused by the excessive presence of metal elements in transformer oil continue to occur, but there are neither national standards nor industry standards for the determination of metal elements in transformer oil. This is a serious problem that needs to be solved urgently.

The first is that in recent years, there have been many major power equipment failures caused by the excessive presence of metal elements in transformer oil; the second is that there is no standard method for metal elements in transformer oil, which leads to high cost and low efficiency of fault treatment, which directly affects safe operation of the power grid.

Contents of the invention

The technical problem solved by the invention is to provide a method for pretreatment of transformer oil and quantitative determination of metal elements therein.

The present invention adopts following technical scheme:

(1) Transformer oil analysis sample among the present invention is quantitatively weighed after the oil sample heating shakes up of collection;

(2) the present invention adopts infrared heating method to carry out constant temperature evaporation and carbonization to quantitative transformer oil analysis sample;

(3) The present invention adopts box-type high-temperature furnace to carry out high-temperature ashing to the sample after carbonization;

(4) The present invention dissolves the ashed sample with an acid solution under low-temperature heating conditions;

(5) The present invention uses dilute acid solution to dilute and constant volume the dissolved sample to prepare an analysis solution;

(6) Analyzing the solution Use a full-spectrum direct-reading plasma emission spectrometer to accurately determine the content of various metal elements.

The transformer oil analysis sample described in the present invention is to quantitatively weigh the collected oil sample after being heated and shaken, that is, heated at 50-60°C for 15-20min, taken out and shaken, the weighing range of the transformer oil analysis sample Controlled at 10g-20g, and accurate to 0.001g, the sample is placed in a dry and clean quartz beaker.

According to the present invention, the infrared heating method is used to conduct constant temperature evaporation and carbonization of quantitative transformer oil analysis samples. The infrared heating step is to use a temperature-controllable ceramic infrared electric heating plate at a temperature of 260°C ± 10°C until it is completely carbonized. .

According to the present invention, the carbonized sample is subjected to high-temperature ashing. The high-temperature ashing is to slowly raise the temperature from room temperature to 625°C and keep it at 625°C±5°C for 60 minutes. Slowly raise the room temperature to 625°C, and keep it at 625°C±5°C for 60 minutes, which is conducive to thorough ashing.

According to the present invention, the sample after ashing is dissolved with an acid solution under low-temperature heating conditions. The step of heating and dissolving with an acid is to first add 1:1 HNO ₃ 4.5-5.5ml, and then add 1:1 HCl 13.5 -16.5ml, heat and dissolve at 80-110°C until the solution is concentrated to 1-3ml, that is, add 1:1 HNO ₃ first, then add 1:1 HCl (wherein HNO ₃ and HCl The addition ratio is 1:3), and heated at low temperature to dissolve until the remaining 1-3ml of the solution.

The dilute acid solution of the present invention is used to dilute and constant volume the dissolved sample to prepare an analysis solution. The dilute nitric acid is used to quantitatively dilute the solution into a volumetric flask of 25ml-50ml with 2% dilute nitric acid;

The analytical solution of the present invention uses a full-spectrum direct-reading plasma emission spectrometer to accurately measure the contents of various metal elements.

Transformer oil analysis sample of the present invention is handled according to two kinds of situations: the first kind of situation is that if transformer oil is unused, clean, new transformer oil, the transformer oil that can be collected directly is analyzed sample by weighing, The second situation is that if the transformer oil is used and has impurities, the collected transformer oil needs to be kept at a temperature of 55±5°C for 10-15 minutes, and then shaken and weighed as an analysis sample.

The conditions of the full-spectrum direct-reading plasma emission spectrometer that the present invention carries out multi-element simultaneous measurement are: step grating, CID charge injection detector, high-frequency generator working power 1150W, ICP frequency is 27.12MHZ, carrier gas (atomization Gas) flow rate 1.0L/min, auxiliary gas flow rate 1.0L/min, plasma gas flow rate 1.0L/min, sample volume 1.85ml/min, atomizer pressure 28psi, peristaltic pump speed 130Z/min.

The dilute constant volume described in the present invention is to quantitatively dilute the solution to a 25ml- or 50ml volumetric flask with 2% dilute nitric acid.

The simultaneous determination of multiple elements in the present invention refers to the simultaneous determination of copper, iron, zinc, aluminum, chromium, manganese, silver, nickel and other elements in the same treated transformer oil sample solution.

All the utensils in the scheme of the present invention were soaked in 1:1 HNO ₃ for 24 hours before use, washed with high-purity water, and dried for later use. This scheme can overcome the pollution in the experimental process to the greatest extent, and is of great significance to the metal elements that exist in trace amounts.

The positive effects of the present invention are as follows: the presence of a large number of metal impurities in the oil medium seriously affects the insulation performance of the equipment, and can cause safety accidents such as overheating, electrification of oil flow, multi-point grounding, and abnormal discharge, thereby accelerating oil quality deterioration and seriously affecting Safe operation of equipment. By measuring the metal components in the oil medium, the running trend of the oil medium can be grasped. If the content of a certain element or several elements is found to increase rapidly or change abnormally, it can be judged in time which part of the component may be abnormal. Abrasion, corrosion, overheating or discharge, combined with chromatographic indicators and electrical indicators, can accurately determine the specific location of the abnormality.

Detecting the content of metal impurities in the oil medium and mastering the range and development trend of various elements can not only judge the quality of new oil and the operating status of equipment, but also help to take targeted operations in time to ensure maximum The device is operating in a safe state.

The present invention combines the parts materials of the transformer and the degree of influence on operation safety, and screens out nine elements such as copper, iron, zinc, chromium, manganese, silver, and aluminum from various aspects that are beneficial to fault judgment, cause finding, and instrument analysis. The first domestic infrared heating method is used for sample carbonization, high temperature ashing, and finally the method of acid dissolution for sample treatment, and then dilute acid solution is used to fix the volume, and the full-spectrum direct-reading plasma emission spectrometer is used to complete the process under the best optimized conditions. For the quantitative determination of metal elements, the precision and accuracy of the method and the recovery rate of standard addition were tested with American constand s-21 standard mixed oil, and satisfactory results were obtained. The method of the invention measures many elements and has high accuracy, and can measure oil media of different types (including transformer oil, lubricating oil, etc.) and different content ranges (ppb to ppm). The accurate determination of elements can ensure the accurate positioning of faults, accurately reflect the change trend of metals in the oil medium, facilitate accurate analysis, and discover hidden dangers in time; it can ensure the safe and stable operation of equipment.

The development of the method of the present invention has also overcome defects such as the direct sampling method can only measure oil-soluble metals, can only measure particles less than several microns, and the metal content is less than 10ppb and is not easy to measure accurately; Tolerance, and will not bring in other impurities due to the introduction of a large amount of aviation kerosene as a diluent.

The heating method adopted in the present invention can ensure that the heated transformer oil is heated quickly and evenly without splashing and introducing other impurities. The invention adopts mixed acid dissolution to simultaneously measure oil-soluble and non-oil-soluble metal elements, and can measure metal elements with different particle sizes and different content ranges. Using full-spectrum direct-reading plasma emission spectrometer can realize the simultaneous determination of various metal elements with different contents.

The non-insulating impurity content in the oil medium is generally relatively small, but when an abnormal situation occurs, the metal content in it can increase hundreds of times, and the impurity content can vary greatly, from several ppb to several ppm. Moreover, oil There are various types of impurity elements that may exist in the medium. The method of the invention adopts the inductively coupled plasma emission spectrometry, which has high sensitivity, good accuracy, less interference between elements, wide linear range of the working curve, and can simultaneously measure multiple elements.

In the ashing acid-dissolving method, the sample is heated and carbonized and ashed at high temperature, and then dissolved in acid into an aqueous solution for spectrometer measurement. The ashing and acid-dissolving method has a wide range of adaptation to the sample. Regardless of the degree of contamination of the sample or not, regardless of the size of the impurity particles in the sample, the content range of the metal element can also be very wide (can be adjusted by the sampling volume). Satisfactory measurement results were obtained.

The invention is applicable both to new transformer oil and to used or ongoing transformer oil.

Detailed ways

The types and particle sizes of metal elements are different, and the states in the oil are not exactly the same. Some are in a suspended state, suspended in the oil, and some metals with large particles and large specific gravity will settle at the bottom of the oil. Then, heating the sample at 50-60°C not only reduces the viscosity of the oil medium, which is convenient for weighing, but also makes the impurities in it uniform. Therefore, before testing and sampling, first heat the oil sample to 50-60°C and keep it for 15-20min, then mix and weigh the sample.

Choose a ceramic infrared electric heating plate to heat the sample, which can keep the temperature difference of the entire liquid relatively small, easy to control the temperature, and high heating efficiency. It takes about 4-6 hours to heat and evaporate a 10-gram sample. The oil sample is allowed to evaporate to dryness without formation of combustion spatter or process contamination, resulting in rapid and complete carbonization.

The experimental results show that the measured values of lead and manganese are low when the ashing temperature is 600°C, and the measured values of each element can meet the requirements when the ashing temperature is 625°C. Therefore, according to the measurement results and comprehensive factors, the final selection of the ashing temperature is 625°C , The ashing time is 60 minutes.

Using only 1:1 HCl or 1:1 HNO ₃ to treat the sample, the variation range of the instrument measurement results is relatively large, and the repeatability is not very good. Later, 5ml of 1:1 HNO ₃ was added first, and then 15ml of 1:1 HCl was added, and the effect of dissolving the sample was very good. Not only was the sample dissolved completely, but also the repeatability of sample determination was satisfactory. In addition, by investigating the emission intensity of each element in the standard solution under different acidity, wherein the acidity is respectively 1%, 2%, 5%, 7% four cases, the experimental data shows: when the acidity is controlled at 2% and 5%, The determination results of each element are satisfactory. Therefore, a solution acidity of 2% is used, and the acidity of the sample is consistent with that of the standard solution.

Example 1: Put the collected representative oil medium into a constant temperature oven, heat it at 50-60°C for 15-20min, take it out and shake it well. Accurately weigh 10.000g or 20.000g (determined according to the size of the impurity content to ensure that the ashing amount of the sample is appropriate) in a 50ml quartz beaker, place it on a ceramic infrared heating plate, open the ventilation facility, and adjust the temperature to 260°C Heat the sample until the sample turns into a black solid, and then continue heating for 30 minutes. Then place the quartz beaker carefully in a high-temperature furnace, raise the temperature from room temperature to 625°C, and keep it at 625°C for 60 minutes to ensure thorough ashing.

After ashing, remove to cool. Add 5ml of 1:1 _HNO3 to the quartz beaker, then add 15ml of 1:1 HCl, adjust the temperature of the electric heating plate to 100°C, heat the solution to 1-3ml, cool, and transfer the sample _solution to Dilute to volume in a 25ml polyethylene volumetric flask.

The solution after constant volume was determined on a full-spectrum direct-reading plasma emission spectrometer in accordance with the best instrument parameters and experimental conditions for the determination of various metal elements. The best measured spectral lines for each element are shown in the table below.

The best measured spectral lines of each element

Determining element Aluminum Al Chromium Cr Copper Cu Iron Fe Lead Pb The best spectral line nm 396.152 283.563 324.754 259.940 220.353 Determining element Manganese Mn Nickel Ni Silver Ag Zinc Zn The best spectral line nm 257.610 221.647 328.068 213.856

Embodiment 2: The transformer oil analysis sample of the present invention is the collected oil sample, which is heated and shaken, and quantitatively weighed, that is, heated at 50°C for 15 minutes, taken out and shaken, and the weighing range of the transformer oil analysis sample is controlled at 15g ;

The present invention adopts the infrared heating method to carry out constant temperature evaporation and carbonization on the quantitative transformer oil analysis sample, and the infrared heating step is to use a temperature-controllable ceramic infrared electric heating plate at a temperature of 250 ° C until it is completely carbonized;

The present invention performs high-temperature ashing on the carbonized sample, and the high-temperature ashing is to slowly raise the temperature from room temperature to 625°C, and keep it at 625°C for 60 minutes;

The present invention uses an acid solution to dissolve the ashed sample under low-temperature heating conditions. The step of heating and dissolving with an acid is to first add 1:1 HNO ₃ 5ml, then add 1:1 HCl15ml, and heat at 95°C. Dissolve until the solution is concentrated to 3ml;

The present invention uses dilute acid solution to dilute and constant volume the dissolved sample to prepare an analysis solution, and dilute to volume with 2% dilute nitric acid to quantitatively dilute the solution into a 50ml volumetric flask;

The analysis solution of the present invention uses a full-spectrum direct-reading plasma emission spectrometer to accurately measure the contents of various metal elements.

The transformer oil analysis sample of the present invention is processed according to two situations: the first situation is that if the transformer oil is unused, clean and new transformer oil, the transformer oil collected can be directly weighed to be the analysis sample, and the second situation is The situation is that if the transformer oil is used and has impurities, the collected transformer oil needs to be kept at 55°C for 10 minutes, and then shaken and weighed as an analysis sample.

The conditions of the full-spectrum direct-reading plasma emission spectrometer that the present invention carries out multi-element simultaneous measurement are: step grating, CID charge injection detector, high-frequency generator working power 1150W, ICP frequency is 27.12MHZ, carrier gas (atomization Gas) flow rate 1.0L/min, auxiliary gas flow rate 1.0L/min, plasma gas flow rate 1.0L/min, sample volume 1.85ml/min, atomizer pressure 28psi, peristaltic pump speed 130Z/min.

Embodiment 3: The transformer oil analysis sample of the present invention is the collected oil sample, which is heated and shaken, and quantitatively weighed, that is, heated at 55°C for 17 minutes, taken out and shaken, and the weighing range of the transformer oil analysis sample is controlled at 10g ;

The present invention adopts the infrared heating method to carry out constant temperature evaporation and carbonization on the quantitative transformer oil analysis sample, and the infrared heating step is carried out at a temperature of 260°C±10°C by using a temperature-controllable ceramic infrared electric heating plate until it is completely carbonized;

The present invention performs high-temperature ashing on the carbonized sample, and the high-temperature ashing is to slowly raise the temperature from room temperature to 625°C, and keep it at 625°C for 60 minutes;

The present invention uses acid solution to dissolve the ashed sample under low-temperature heating conditions. The step of heating and dissolving with acid is to add 1:1 HNO ₃ 5.5ml, then add 1:1 HCl 16.5ml, and heat the sample at 110°C. Heat and dissolve at low temperature until the solution is concentrated to 2ml;

The present invention uses dilute acid solution to dilute and constant volume the dissolved sample to prepare an analysis solution, and dilute to volume with 2% dilute nitric acid to quantitatively dilute the solution into a 50ml volumetric flask;

The analysis solution of the present invention uses a full-spectrum direct-reading plasma emission spectrometer to accurately measure the contents of various metal elements.

The transformer oil analysis sample of the present invention is processed according to two situations: the first situation is that if the transformer oil is unused, clean and new transformer oil, the transformer oil collected can be directly weighed to be the analysis sample, and the second situation is The situation is that if the transformer oil is used and has impurities, the collected transformer oil needs to be kept at a temperature of 50°C for 13 minutes, and then shaken and weighed as an analysis sample.

The conditions of the full-spectrum direct-reading plasma emission spectrometer that the present invention carries out multi-element simultaneous measurement are: step grating, CID charge injection detector, high-frequency generator working power 1150W, ICP frequency is 27.12MHZ, carrier gas (atomization Gas) flow rate 1.0L/min, auxiliary gas flow rate 1.0L/min, plasma gas flow rate 1.0L/min, sample volume 1.85ml/min, atomizer pressure 28psi, peristaltic pump speed 130Z/min.

Embodiment 4: The transformer oil analysis sample of the present invention is the collected oil sample, which is heated and shaken, and quantitatively weighed, that is, heated at 60°C for 20 minutes, taken out and shaken, and the weighing range of the transformer oil analysis sample is controlled at 20g ;

The present invention adopts the infrared heating method to carry out constant temperature evaporation and carbonization on the quantitative transformer oil analysis sample, and the infrared heating step is to use a temperature-controllable ceramic infrared electric heating plate at a temperature of 270°C until it is completely carbonized;

The present invention performs high-temperature ashing on the carbonized sample, and the high-temperature ashing is to slowly raise the temperature from room temperature to 625°C, and keep it at 625°C for 60 minutes;

The present invention uses acid solution to dissolve the ashed sample under low-temperature heating conditions. The step of heating and dissolving with acid is to first add 1:1 HNO ₃ 4.5ml, then add 1:1 HCl 13.5ml, and heat the sample at 80°C. Heat and dissolve at low temperature until the solution is concentrated to 1ml;

The present invention uses dilute acid solution to dilute the dissolved sample and make it constant to prepare an analysis solution. The dilute and constant volume is to quantitatively dilute the solution into a 25ml volumetric flask with 2% dilute nitric acid;

The analysis solution of the present invention uses a full-spectrum direct-reading plasma emission spectrometer to accurately measure the contents of various metal elements.

The transformer oil analysis sample of the present invention is processed according to two situations: the first situation is that if the transformer oil is unused, clean and new transformer oil, the transformer oil collected can be directly weighed to be the analysis sample, and the second situation is The situation is that if the transformer oil is used and has impurities, the collected transformer oil needs to be kept at a temperature of 60°C for 15 minutes, and then shaken and weighed as an analysis sample.

The conditions of the full-spectrum direct-reading plasma emission spectrometer that the present invention carries out multi-element simultaneous measurement are: step grating, CID charge injection detector, high-frequency generator working power 1150W, ICP frequency is 27.12MHZ, carrier gas (atomization Gas) flow rate 1.0L/min, auxiliary gas flow rate 1.0L/min, plasma gas flow rate 1.0L/min, sample volume 1.85ml/min, atomizer pressure 28psi, peristaltic pump speed 130Z/min.

Claims (2)

1. determination method multiple metallic element time the in the transformer oil is characterized in that:

(1) the transformer oil analytic sample among the present invention is heated for the oil sample of gathering and is quantitatively taken by weighing after shaking up, and promptly at 50-60 ℃ of heating 15-20min down, taking-up shakes up, and the range of weighing of described transformer oil analytic sample is controlled at 10g-20g;

(2) the present invention adopts the Infrared Heating method that quantitative transformer oil analytic sample is carried out evaporation at constant temperature and carbonization, and the Infrared Heating step is to adopt the ceramic infrared electric heating plate of controllable temperature to carry out under 260 ℃ ± 10 ℃ temperature, till carbonization;

(3) sample after the present invention adopts box high temperature furnace to carbonization carries out the high temperature ashing, and the high temperature ashing is slowly to be warmed up to 625 ℃ from room temperature, and keeps 60 minutes down at 625 ℃ ± 5 ℃;

(4) the present invention adopts and to dissolve with the sample of acid solution after to ashing under the low-temperature heat condition, and step is: the HNO that adds 1: 1 earlier ₃4.5-5.5ml, add 1: 1 HCl13.5-16.5ml again, under 80-110 ℃ of temperature heating for dissolving to solution concentration to 1-3ml;

(5) sample after the present invention adopts dilute acid soln to dissolving dilutes and constant volume, is prepared into analysis solution, and the dilution constant volume is solution quantitatively to be diluted in the volumetric flask of 25ml-50ml with rare nitric acid of 2%;

(6) analytical solution is accurately measured the content of multiple metallic element with full spectrum direct-reading plasma emission spectrometer.

2. determination method multiple metallic element time the in a kind of transformer oil according to claim 1, the condition that it is characterized in that carrying out the full spectrum direct-reading plasma emission spectrometer of multielement simultaneous determination is: echelle grating, the pouring-in detecting device of CID electric charge, radio-frequency generator operating power 1150W, the ICP frequency is 27.12MHZ, carrier gas (atomization gas) flow 1.0L/min, secondary air amount 1.0L/min, plasma gas flow rate 1.0L/min, sample size 1.85ml/min, atomizer pressure is 28psi, peristaltic pump rotating speed 130Z/min.