CN107389809B - FR3 vegetable insulating oil oil dissolved gas ostwald coefficient measuring method - Google Patents

Abstract

The present invention provides a kind of FR3 vegetable insulating oil oil dissolved gas ostwald coefficient measuring method, comprising the following steps: configures standard mixture as desired；Prepare FR3 vegetable insulating oil blank oil sample；Prepare FR3 vegetable insulating oil sample oil sample；50 DEG C of balanced oscillations next time extract balanced oscillations gas；Secondary balanced oscillations at 50 DEG C extract balanced oscillations gas, and accurate recording degassed volume；Gas chromatographic analysis；Sample oil dissolved gas each component calculates；50 DEG C of ostwald coefficient K of FR3 vegetable insulating oil are calculated_i, the present invention can accurately detect and obtain FR3 vegetable insulating oil oil dissolved gas ostwald coefficient at 50 DEG C, to carry out accurate quantitative analysis calculating to FR3 vegetable insulating oil oil dissolved gas each component content.

Description

Method for Determination of Ostwald Coefficient of Dissolved Gases in FR3 Vegetable Insulating Oil

technical field

The invention relates to the calculation of the dissolved gas content in vegetable insulating oil, in particular to a method for measuring the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil at 50°C.

Background technique

As a substitute product of traditional mineral insulating oil, vegetable insulating oil has always been a research hotspot at home and abroad. Its advantages in high safety performance (high ignition point), environmental protection (high biodegradation rate) and other aspects are unmatched by mineral insulating oils. Vegetable oils and mineral oils belong to different classes of organic substances. The main components of mineral oil are saturated hydrocarbons, such as alkanes (CnH2n+2) and naphthenes (CnH2n, CnH2n-2, CnH2n-4), and their molecules are only composed of carbon and hydrogen atoms. Vegetable oils are esters, which are composed of a series of triglycerides of fatty acids. Triglyceride molecules are composed of glycerol groups and fatty acid groups (RCOO-), containing not only carbon and hydrogen atoms, but also oxygen atoms. Hydrocarbons have both similarities and differences in molecular composition and structural features. The similarity is manifested in: both have long carbon chains and macromolecular structures, and the main constituent elements are carbon atoms and hydrogen atoms. The difference is as follows: each fatty acid group of esters contains two oxygen atoms, and the fatty acid groups that make up triglycerides may not be the same. The molecular structure of esters is generally asymmetric, so it has a certain polarity, while saturated hydrocarbons do not Containing oxygen atoms, the molecular structure is symmetrical and has no polarity. Therefore, the unique molecular composition and structural characteristics of vegetable insulating oils cause differences in the basic physical and chemical properties of vegetable insulating oils and mineral insulating oils. For example, the performance parameters such as flash point, kinematic viscosity, dielectric loss factor, water content, and dielectric constant of vegetable insulating oil are higher than those of mineral insulating oil.

According to incomplete statistics, vegetable insulating oil transformers have been used in foreign countries for more than 10 years, with 500,000 sets of applications. At present, the highest voltage level of a single vegetable insulating oil transformer in the world has reached 420kV, and the maximum capacity has reached 300MVA. Dissolved gas analysis (DGA) in insulating oil is recognized as the most sensitive detection method to reflect the internal faults of oil-filled electrical equipment. When there are defects and hidden dangers inside the transformer, when conducting related electrical tests, such as withstand voltage test, impact test, temperature rise test, etc., the fault characteristic gas corresponding to the fault nature will be generated in the insulating oil due to the internal defects of the equipment, so The operating status of the equipment can be evaluated by analyzing the dissolved gas components and content in the insulating oil before and after the electrical test of the high-voltage equipment.

Accurately detecting the gas content of each fault characteristic of dissolved gas in vegetable insulating oil is the basis for carrying out the analysis of dissolved gas in vegetable insulating oil transformer oil. According to the existing calculation formula for the content of dissolved gas components in mineral insulating oil, it can be known that the Ostwald coefficient of dissolved gas in vegetable insulating oil is a key technical parameter in the calculation formula. At present, there is no relevant standard in China to give the Ostwald coefficient of dissolved gas in vegetable insulating oil. Therefore, it is very necessary to accurately determine the Ostwald coefficient of dissolved gas in vegetable insulating oil.

Contents of the invention

The invention provides a method for measuring the Ostwald coefficient of dissolved gas in oil at 50 DEG C of FR3 vegetable insulating oil. It fills up the domestic gap in the determination of the Ostwald coefficient of dissolved gas in vegetable insulating oil.

Technical solution of the present invention: a method for measuring the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil, comprising the following steps:

Configure the mixed standard gas according to the demand;

Prepare FR3 vegetable insulating oil blank oil sample;

Prepare FR3 vegetable insulating oil sample oil sample;

Inject carrier gas, oscillate to balance at 50°C, and extract a oscillating equilibrium gas;

Record the temperature and atmospheric pressure of the chromatographic detection laboratory, and perform gas chromatographic analysis on the extracted primary oscillation equilibrium gas on the chromatograph; record the primary oscillation equilibrium gas detection peak height/peak area;

Re-inject the carrier gas, and oscillate for the second time to balance at 50°C;

Extract the secondary oscillation equilibrium gas, and accurately record the secondary oscillation equilibrium gas at room temperature;

Carry out gas chromatographic analysis on the extracted secondary oscillation equilibrium gas on the chromatograph, and record the detection peak height/peak area of the secondary oscillation equilibrium gas;

Convert the secondary oscillation equilibrium degassed gas to 50°C by formula (1),

V'_'g is the measured volume of the equilibrium gas after equilibrium under the test pressure and temperature as t,

V″ _g is the equilibrium gas volume at 50°C under the test pressure;

Convert the test oil volume of FR3 vegetable insulating oil to 50°C by formula (2),

V ₀ ”＝V’ ₀ ×[1+0.0074×(50-t)] (2)

V ₀ ′ is the measured volume of the degassed sample oil sample at a temperature of t, and V ₀ ″ is the degassed sample oil

The volume of the sample at a temperature of 50°C, 0.0074 is the thermal expansion coefficient of FR3 vegetable insulating oil;

According to the distribution law and the principle of material balance, the Ostwald coefficient K _i of the component at 50°C is obtained according to formula (3)

In the formula: K _i ——the Ostwald coefficient of component i at a temperature of 50°C;

c _{ig —concentration} of dissolved gas component i in the gas after the first equilibrium;

c' _ig - the concentration of the dissolved gas i component in the gas after the second equilibrium;

V″ _g ——the volume of gas at a temperature of 50°C after the second equilibrium;

V ₀ ″——the liquid volume at a temperature of 50°C after the second equilibrium.

In the step of configuring the mixed standard gas, the mixed standard gas includes hydrogen H ₂ , carbon monoxide CO, carbon dioxide CO ₂ , methane CH ₄ , ethylene C ₂ H ₄ , ethane C ₂ H ₆ , acetylene C ₂ H ₂ and as base gas Nitrogen or argon, the concentration of mixed gas can be configured according to the concentration of each component of mineral insulating oil standard gas.

The preparation method of the blank oil sample of FR3 vegetable insulating oil is as follows: Inject 20ml of FR3 vegetable insulating oil into 6-8 50ml glass syringes, then inject 20ml of carrier gas, and use a constant temperature timing mechanical oscillator to continuously shake at 50°C for 20 minute, stand for 10 minutes, repeat the operation 5 times, and detect the blank oil sample of the prepared FR3 vegetable insulating oil on the chromatograph until the concentration of each component of the dissolved gas in the oil is lower than the minimum detection limit of the chromatograph, so as to obtain the A blank oil sample of FR3 vegetable insulating oil is required.

The preparation of the FR3 vegetable insulating oil sample oil sample includes: sealing and filling 20ml of the prepared mixed standard gas into 6-8 20ml blank FR3 vegetable insulating blank oil respectively; using a constant temperature timing mechanical oscillator to continuously vibrate at 50°C for 60 minutes , and then placed in a 50°C incubator for 12 hours to ensure that the FR3 vegetable insulating oil and the mixed standard gas are fully balanced.

The injected carrier gas is argon or nitrogen.

Technical effect of the present invention: the present invention can accurately detect and obtain the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil at 50°C, thereby accurately calculating the contents of each component of dissolved gas in FR3 vegetable insulating oil.

Detailed ways

The present invention will be further described in detail below in conjunction with the examples, the following examples are explanations of the present invention and the present invention is not limited to the following examples.

A method for measuring the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil oil, comprising the following steps:

Configure the mixed standard gas according to the demand;

Prepare FR3 vegetable insulating oil blank oil sample;

Prepare FR3 vegetable insulating oil sample oil sample;

Inject carrier gas, oscillate to balance at 50°C, and extract a oscillating equilibrium gas;

Record the temperature and atmospheric pressure of the chromatographic detection laboratory, and perform gas chromatographic analysis on the extracted primary oscillation equilibrium gas on the chromatograph; record the primary oscillation equilibrium gas detection peak height/peak area;

Re-inject the carrier gas, and oscillate for the second time to balance at 50°C;

Extract the secondary oscillation equilibrium gas, and accurately record the secondary oscillation equilibrium gas at room temperature;

Carry out gas chromatographic analysis on the extracted secondary oscillation equilibrium gas on the chromatograph, and record the detection peak height/peak area of the secondary oscillation equilibrium gas;

Convert the secondary oscillation equilibrium degassed gas to 50°C by formula (1),

V'_'g is the measured volume of the equilibrium gas after equilibrium under the test pressure and temperature as t,

V″ _g is the equilibrium gas volume at 50°C under the test pressure;

Convert the test oil volume of FR3 vegetable insulating oil to 50°C by formula (2),

V ₀ ″=V' ₀ ×[1+0.0074×(50-t)] (2)

V ₀ ′ is the measured volume of the degassed sample oil sample at a temperature of t, and V ₀ ″ is the degassed sample oil

The volume of the sample at a temperature of 50°C, 0.0074 is the thermal expansion coefficient of FR3 vegetable insulating oil;

According to the distribution law and the principle of material balance, the Ostwald coefficient K _i of the component at 50°C is obtained according to formula (3)

In the formula: K _i ——the Ostwald coefficient of component i at a temperature of 50°C;

c _{ig —concentration} of dissolved gas component i in the gas after the first equilibrium;

c' _ig - the concentration of the dissolved gas i component in the gas after the second equilibrium;

V″ _g ——the volume of gas at a temperature of 50°C after the second equilibrium;

V ₀ ″——the liquid volume at a temperature of 50°C after the second equilibrium.

In the step of configuring the mixed standard gas, the mixed standard gas includes hydrogen H ₂ , carbon monoxide CO, carbon dioxide CO ₂ , methane CH ₄ , ethylene C ₂ H ₄ , ethane C ₂ H ₆ , acetylene C ₂ H ₂ and as base gas Nitrogen or argon, the concentration of mixed gas can be configured according to the concentration of each component of mineral insulating oil standard gas.

The preparation method of the blank oil sample of FR3 vegetable insulating oil is as follows: Inject 20ml of FR3 vegetable insulating oil into 6-8 50ml glass syringes, then inject 20ml of carrier gas, and use a constant temperature timing mechanical oscillator to continuously shake at 50°C for 20 minutes, stand for 10 minutes, repeat the operation 5 times, and detect the blank oil sample of the prepared FR3 vegetable insulating oil on the chromatograph until the concentration of each component of the dissolved gas in the oil is lower than the minimum detection limit of the chromatograph, so as to obtain the A blank oil sample of FR3 vegetable insulating oil is required.

The preparation of the FR3 vegetable insulating oil sample oil sample includes: sealing and filling 20ml of the prepared mixed standard gas into 6-8 20ml blank FR3 vegetable insulating blank oil respectively; using a constant temperature timing mechanical oscillator to continuously vibrate at 50°C for 60 minutes , and then placed in a 50°C incubator for 12 hours to ensure that the FR3 vegetable insulating oil and the mixed standard gas are fully balanced.

The injected carrier gas is argon or nitrogen.

Example:

The measurement method is described in detail below.

1. Testing instruments and equipment: The main testing instruments and equipment for Ostwald coefficient of dissolved gas in plant insulating oil include: gas chromatograph (including hydrogen flame ionization detector and thermal conductivity detector), constant temperature timing mechanical oscillator, 7 10ml, 20ml, 50ml, 100ml fully sealed glass syringes, 1ml fully sealed injection syringe, high-purity air or air generator, high-purity argon or nitrogen, high-purity hydrogen or hydrogen generator.

2. Preparation of mixed standard gas: the concentration preparation of mixed standard gas is shown in Table 1.

Table 1 Concentration of each component of mixed standard gas

gas composition H2 CO CO2 CH4 C2H4 C2H6 C2H2 Ar Concentration (uL/L) 491 497 2980 98.6 99.4 95.1 48.7 Confidence

3. Preparation of blank oil sample: The blank oil sample of FR3 vegetable insulating oil can be prepared by the following method: inject 20ml of FR3 vegetable insulating oil into seven 50ml glass syringes, and then inject 20ml of carrier gas (argon or nitrogen), use The constant temperature timing mechanical oscillator in right 4 oscillates continuously at 50°C for 20 minutes, rests for 10 minutes, and repeats the operation 5 times to obtain the required blank oil sample of FR3 vegetable insulating oil. Table 2 shows the peak heights of each component detected in the FR3 plant insulating oil blank oil sample on the chromatograph.

Table 2 FR3 vegetable insulating oil blank oil sample detection peak height (mV)

gas composition H2 CO CO2 CH4 C2H4 C2H6 C2H2 Detection peak (mV) 0 0.037 3.601 0.122 0.015 0.159 0

4. Oil sample preparation of FR3 vegetable insulating oil samples: Seal and fill 20ml of the mixed standard gas prepared in Table 1 into seven 20ml blank FR3 vegetable insulating blank oils in Table 2; Shake for 60 minutes, then put it in a 50°C incubator and let it stand for 12 hours to ensure that the FR3 vegetable insulating oil and the mixed standard gas are fully balanced. A standard oil sample of FR3 vegetable insulating oil for detecting the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil can be obtained.

5. Record the environmental conditions detected by gas chromatography. Record chromatographic detection laboratory testing conditions: laboratory atmospheric pressure: 101.6kPa; laboratory room temperature: 21°C.

6. Gas chromatographic analysis of degassed gas with one shake equilibrium. Use 20ml fully sealed glass syringes to take out all the equilibrium gases in the 7 syringes after the first oscillation balance in right 7 (no need to measure the gas volume). Tested in the laboratory with a gas chromatograph that has been running stably. Table 3 shows the detection peak heights (mV) of the concentration of each gas component in the seven sample oils after the first oscillation equilibrium.

Table 3 The peak height of each component concentration detection in the sample gas after the first oscillation balance (mV)

Component H2 CO CO2 CH4 C2H4 C2H6 C2H2 1#-1 gas sample 5.062 17.853 13.715 42.287 22.974 15.561 7.095 2#-1 gas sample 5.123 17.909 13.146 42.187 22.439 15.137 6.905 3#-1 gas sample 5.023 17.718 13.107 41.661 22.441 15.204 6.915 4#-1 gas sample 4.929 17.867 13.625 40.834 22.665 15.339 6.975 5#-1 gas sample 5.100 17.748 13.521 41.737 21.617 14.539 6.591 6#-1 gas sample 4.785 17.200 12.887 39.349 21.264 14.353 6.537 7#-1 gas sample 5.193 17.945 13.468 41.891 22.011 14.802 6.712 average 5.031 17.749 13.353 41.421 22.202 14.991 6.819 STD 0.136 0.255 0.307 1.029 0.603 0.440 0.208

7. Inject carrier gas (argon or nitrogen): Inject 20ml of argon into the 7 FR3 vegetable insulating oil samples after the first oscillation balance, and perform the second oscillation balance at a constant temperature of 50°C.

8. Record the degassing volume of the secondary oscillation equilibrium: take out all the degassed gas after the secondary oscillation equilibrium, and accurately read the gas volume after equilibrium in the detection environment and record it. The degassed volume after the second oscillation balance is shown in Table 4.

Table 4 The degassed volume after the second oscillation balance (ml)

Sample serial number 1# 2# 3# 4# 5# 6# 7# average value Degassing volume (ml) 19 19 20 19 19 18 20 19.14

9. Gas chromatographic analysis of secondary oscillation equilibrium degassed gas: analyze the peak concentration of each detected component in the secondary equilibrium gas with a laboratory gas chromatograph at room temperature. Table 5 shows the volume of gas taken out after the second balance, and Table 5 shows the detected values (peak height mV) of each component concentration of dissolved gas in the second balance gas oil at 50°C.

Table 5 The peak height of each component concentration detection in the sample gas after the second oscillation balance (mV)

Component H2 CO CO2 CH4 C2H4 C2H6 C2H2 1#-2 gas sample 0.336 1.044 6.692 10.12 12.665 9.328 4.533 2#-2 gas sample 0.271 1.292 6.588 10.093 12.313 9.011 4.342 3#-2 gas sample 0.264 1.158 6.934 10.166 12.977 9.536 4.624 4#-2 gas sample 0.286 1.355 6.626 10.179 11.911 8.727 4.137 5#-2 gas sample 0.268 1.464 7.376 10.192 12.61 9.281 4.417 6#-2 gas sample 0.269 1.445 7.181 9.872 12.408 9.163 4.347 7#-2 gas sample 0.33 1.459 7.138 9.641 12.467 9.236 4.421 average 0.289 1.317 6.934 10.038 12.479 9.183 4.403 STD 0.031 0.163 0.309 0.206 0.33 0.257 0.155

10. The second oscillation balance degassed gas is converted to 50 ℃.

_{V''g is the measured volume of the equilibrium gas after equilibrium under the test pressure and when the temperature is t, ml V″ g is} the volume of the equilibrium gas at 50°C under the test pressure; ml

11. According to the formula (1), the volume of the equilibrium gas when corrected to 50°C can be obtained:

12. Convert the test oil volume of FR3 vegetable insulating oil to 50°C by formula (2),

V ₀ ″=V' ₀ ×[1+0.0074×(50-t)] (2)

V ₀ ′ is the measured volume of the degassed sample oil sample when the temperature is t, ml;

V ₀ ″ is the volume of the degassed oil sample at a temperature of 50°C, ml;

13. According to the thermal expansion coefficient of FR3 vegetable insulating oil 0.0074/℃, according to the formula (2)

The volume of the test oil can be obtained when it is corrected to 50°C.

V ₀ ″=V' ₀ ×[1+0.0074×(50-t)]=

20×[1+0.0074×(50-21)]=20.429ml

Calculation of Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil at 14.50℃. According to the distribution law and the principle of material balance, the Ostwald coefficient (distribution coefficient) K _i of the component at the measured temperature is obtained according to formula (3)

In the formula: K _i ——the Ostwald coefficient of component i at a temperature of 50°C;

c _{ig —concentration} of dissolved gas component i in the gas after the first equilibrium;

c' _ig - the concentration of the dissolved gas i component in the gas after the second equilibrium;

V″ _g ——the volume of gas at a temperature of 50°C after the second equilibrium;

V ₀ ″——the liquid volume at a temperature of 50°C after the second equilibrium.

15. According to the formula (3), the distribution coefficients of the 7 sample oils at 50°C and 101.3kPa were calculated, and the calculation results are shown in Table 6.

Table 6 Ki of each component of dissolved gas in FR3 oil at 50℃

16. According to the calculation results in Table 6, the average value of the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil at 50°C is obtained. See Table 7

Table 7 Average Ostwald coefficient (Ki) of dissolved gas in FR3 vegetable insulating oil at 50°C

Component H2 CO CO2 CH4 C2H4 C2H6 C2H2 K-mean value of FR3 vegetable oil at 50℃ 0.06 0.10 1.09 0.34 1.33 1.60 1.75

Claims (2)

1. a method for measuring the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil oil, is characterized in that, comprises the following steps: Configure the mixed standard gas according to the demand; Prepare FR3 vegetable insulating oil blank oil sample; Prepare FR3 vegetable insulating oil sample oil sample; Inject carrier gas, oscillate to balance at 50°C, and extract a oscillating equilibrium gas; Record the temperature and atmospheric pressure of the chromatographic detection laboratory, and perform gas chromatographic analysis on the extracted primary oscillation equilibrium gas on the chromatograph; record the primary oscillation equilibrium gas detection peak height/peak area; Re-inject the carrier gas, and oscillate for the second time to balance at 50°C; Extract the secondary oscillation equilibrium gas, and accurately record the secondary oscillation equilibrium gas at room temperature; Carry out gas chromatographic analysis on the extracted secondary oscillation equilibrium gas on the chromatograph, and record the detection peak height/peak area of the secondary oscillation equilibrium gas; Convert the secondary oscillation equilibrium degassed gas to 50°C by formula (1), _V''g is the measured volume of the equilibrium gas after equilibrium under test pressure and temperature t, V″ _g is the equilibrium gas volume at 50°C under the test pressure; Convert the test oil volume of FR3 vegetable insulating oil to 50°C by formula (2), V″ ₀ ＝V′ ₀ ×[1+0.0074×(50-t)] (2) _{V'0 is the measured volume of the degassed sample oil sample at a temperature of t, V″0 is} the volume of the degassed sample oil sample at a temperature of 50°C, and 0.0074 is the thermal expansion coefficient of FR3 vegetable insulating oil; According to the distribution law and the principle of material balance, the Ostwald coefficient K _i of the component at 50°C is obtained according to formula (3) In the formula: K _i ——the Ostwald coefficient of component i at a temperature of 50°C; c _{ig —concentration} of dissolved gas component i in the gas after the first equilibrium; c′ _{ig ——the} concentration of the dissolved gas component i in the gas after the second equilibrium; V″ _g ——the volume of gas at a temperature of 50°C after the second equilibrium; V″ ₀ ——the volume of liquid at a temperature of 50°C after the second equilibrium; In the step of configuring the mixed standard gas, the mixed standard gas includes hydrogen H ₂ , carbon monoxide CO, carbon dioxide CO ₂ , methane CH ₄ , ethylene C ₂ H ₄ , ethane C ₂ H ₆ , acetylene C ₂ H ₂ and as base gas Nitrogen or argon, the concentration of the mixed gas is configured according to the concentration of each component of the mineral insulating oil standard gas; The preparation method of the FR3 vegetable insulating oil blank oil sample is as follows: Inject 20ml of FR3 vegetable insulating oil into 6-8 50ml glass syringes, then inject 20ml of carrier gas, and use a constant temperature timing mechanical oscillator to continuously vibrate at 50°C for 20 minutes , stand still for 10 minutes, repeat the operation 5 times, and detect the blank oil sample of the prepared FR3 vegetable insulating oil on the chromatograph until the concentration of each component of the dissolved gas in the oil is lower than the minimum detection limit of the chromatograph, so as to obtain the required FR3 vegetable insulating oil blank oil sample; The preparation of the FR3 vegetable insulating oil sample oil sample includes: sealing and filling 20ml of the prepared mixed standard gas into 6-8 20ml blank FR3 vegetable insulating blank oil respectively; using a constant temperature timing mechanical oscillator to continuously vibrate at 50°C for 60 minutes , and then placed in a 50°C incubator for 12 hours to ensure that the FR3 vegetable insulating oil and the mixed standard gas are fully balanced. 2. The method for measuring the Ostwald coefficient of dissolved gas in FR3 vegetable insulating oil according to claim 1, characterized in that: the injected carrier gas is argon or nitrogen.