Method for determining T501 content of turbine oil based on infrared spectroscopy
Infrared spectroscopy directly determines the T501 content of turbine oil. By preparing concentration gradient standard solutions and detecting absorbance, and drawing standard curves, it solves the inaccurate detection and safety hazards caused by pretreatment in the prior art, providing a safer and more accurate detection method.
Patent Information
- Application Number
- CN202510841509.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-23
- Publication Date
- 2025-07-25
AI Technical Summary
In the prior art, when determining the content of turbine oil T501, concentrated sulfuric acid, white clay, decolorizing adsorbent or degreased cotton is required to pretreat, resulting in inaccurate detection results and safety hazards.
By using infrared spectroscopy, the concentration gradient standard solution with different T501 contents was prepared, and the absorbance of the phenolic hydroxyl stretching vibration absorption peak was detected using infrared spectrometer, and the standard curve of the standard addition method was drawn to determine the original concentration of T501 in the turbine oil sample, eliminating the pretreatment link.
More accurate test results are achieved, the experimental safety risks are reduced, the risk of using strong acids is avoided, and the safety and accuracy of the test are improved.
Smart Images
Figure CN120369666A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of power oil detection methods, and particularly relates to a method for determining the content of T501 in turbine oil based on infrared spectroscopy. Background Art
[0002] T501 is a commonly used antioxidant, scientifically named 2,6-di-tert-butyl-p-cresol. It is suitable for adding to new oil (including regenerated oil) or slightly aged operating oil. According to the requirements of GB / T7596-2017 "Quality of Mineral Turbine Oil during Power Plant Operation", the content of T501 antioxidant should not be less than 25% of the original measured value of new oil. According to the requirements in GB / T14541-2017 "Guide for Maintenance and Management of Mineral Turbine Oil for Power Plants", for new turbine oil or regenerated oil containing only T501 antioxidant, the content of T501 should not be less than 0.3% - 0.5%, and the content of T501 in operating turbine oil should not be less than 0.15%, otherwise top-up should be carried out. The determination of the content of T501 antioxidant in turbine oil is an important link to ensure the performance and quality of the oil. The following are several commonly used determination methods: Gas chromatography - mass spectrometry (GC / MS): A determination method carried out according to the national standard GB / T7602.4-2017, which is applicable to the determination of the content of T501 antioxidant in unused and operating transformer oil and turbine oil. This method uses the technology of gas chromatography combined with mass spectrometry to accurately determine the content of T501. This method requires the use of blank oil without T501 as a solvent, which is not convenient for procurement and acceptance methods. Spectrophotometry: The GB / T7602.1-2008 standard stipulates the use of spectrophotometry to determine the content of T501. This method is applicable to steam turbine oil and transformer oil in operation. This method uses petroleum ether and ethanol as solvents and phosphomolybdic acid as a color developer. According to the absorbance of the molybdenum blue complex formed by T501 antioxidant and phosphomolybdic acid at 700 nm in a spectrophotometer, and using the relationship that this absorbance value is proportional to the content of T501, the content of T501 antioxidant in transformer oil and steam turbine oil is determined. This method also requires the use of pretreatment reagents and materials such as concentrated sulfuric acid, clay, decolorizing adsorbent, and absorbent cotton to pretreat the oil sample. The pretreatment time is long, the test conditions are relatively dangerous, and the test results are inaccurate. High performance liquid chromatography: According to the GB / T7602.2-2008 standard, high performance liquid chromatography is also an effective method for determining the content of T501. This method uses methanol as an extractant to enrich T501 in the oil, and analyzes the content of T501 dissolved in the extract with a high performance liquid chromatograph, thereby realizing the determination of the content of T501 in the oil. This method requires pretreatment of transformer oil and turbine oil. The pretreatment process is relatively complex, and concentrated sulfuric acid is used for treatment. The test conditions are relatively dangerous, the test results are inaccurate, and the pretreatment process is the same as the above infrared spectroscopy method. Summary of the Invention
[0003] The object of the present invention is to provide a method for determining the content of T501 in turbine oil based on infrared spectroscopy, which solves the problems in the prior art that concentrated sulfuric acid, clay, decolorizing adsorbent or absorbent cotton need to be used for pretreatment of the oil sample to be measured, and the accuracy of the detection result is insufficient.
[0004] The technical solution adopted by the present invention is a method for determining the content of T501 in turbine oil based on infrared spectroscopy, which specifically includes the following steps: S1, using a T501 reference substance and the turbine oil sample to be measured as raw materials, preparing concentration gradient standard solutions with different T501 contents; S2, using an infrared spectrometer to detect the absorbance of the phenolic hydroxyl stretching vibration absorption peak at a wavenumber of 3650 cm -1 for each concentration standard solution; S3, based on the proportional relationship between the absorbance and the T501 concentration, drawing a standard curve of the standard addition method to obtain a standard regression equation; S4, extending the regression equation to the X-axis, and determining the original concentration of T501 in the turbine oil sample to be detected through the intercept.
[0005] The present invention is also characterized in that The steps for preparing the concentration gradient standard solution are specifically as follows: using the turbine oil sample to be detected as a solvent, adding 12.5 μL, 25.0 μL, 37.5 μL, 50.0 μL, and 125.0 μL of T501 standard solution to a 25 mL volumetric flask respectively, and diluting to the scale line with the turbine oil sample to be detected, and mixing evenly.
[0006] The operation of mixing evenly after dilution is carried out by vortex oscillation or ultrasonic oscillation, and the oscillation time is 30 s to 2 min.
[0007] The preparation of the concentration gradient standard solution also includes a turbine oil sample to be detected without adding T501 standard solution, that is, adding 0 mL of T501 standard solution, and diluting to a 25 mL volumetric flask with the turbine oil sample to be detected.
[0008] The standard for using the infrared spectrometer in S2 is: the scanning range of the infrared spectrometer covers the mid-infrared region of 4000 - 400 cm -1 , the scanning speed is set to 32 cm -1 -35 cm -1 , and it is equipped with a liquid absorption cell.
[0009] The optical path of the liquid absorption cell is 0.1 mm to 1 mm.
[0010] In S3, the standard curve is drawn by the standard addition method as follows: taking the content of the T501 standard substance in the turbine oil sample to be detected as the abscissa and the absorbance as the ordinate, the standard curve is drawn.
[0011] In S4, the original concentration of T501 in the turbine oil sample to be detected is determined by the intercept as follows: extending the regression equation to intersect with the X-axis, and the X-axis value corresponding to the intersection point is the original concentration of T501 in the turbine oil sample to be detected.
[0012] The detection accuracy of the absorbance of the infrared spectrometer at the wavenumber of 3650 cm⁻¹ is within ±0.01 AU.
[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) For the method for determining the content of T501 in turbine oil based on the infrared spectroscopy provided by the present invention, directly using the oil sample to be detected as the solvent to prepare the standard solution, omitting all pretreatment links, and the detection effect is more accurate.
[0014] (2) For the method for determining the content of T501 in turbine oil based on the infrared spectroscopy provided by the present invention, the test personnel do not need to wear protective equipment such as gas masks and acid-alkali resistant gloves, and the laboratory does not need to be equipped with a strong acid waste liquid treatment system, and the risk of safety accidents is reduced by more than 90%. Description of the Drawings
[0015] Figure 1 is a schematic flow chart of the method for determining the content of T501 in turbine oil based on the infrared spectroscopy of the present invention; Figure 2 is a schematic diagram of the effect of the standard addition method on the content of T501 in the oil sample to be detected of the present invention. Detailed Embodiments
[0016] The present invention will be described in detail below in conjunction with the drawings and specific embodiments. The described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.
[0017] Embodiment 1 The present invention provides a method for determining the content of T501 in turbine oil based on the infrared spectroscopy, as Figure 1 shown, including the following steps: S1, using the T501 standard substance and the turbine oil sample to be detected as raw materials, preparing concentration gradient standard solutions with different T501 contents; S2, using an infrared spectrometer to detect the absorbance of the phenolic hydroxyl stretching vibration absorption peak of each concentration standard solution at the wavenumber of 3650 cm -1 ; S3, based on the proportional relationship between the absorbance and the T501 concentration, drawing the standard curve of the standard addition method to obtain the standard regression equation; S4. Extend the regression equation to the X-axis and determine the original concentration of T501 in the turbine oil sample to be detected through the intercept.
[0018] Example 2 This example provides a method for determining the content of T501 in turbine oil based on infrared spectroscopy, as Figure 1 shown, including the following steps: S1. Using T501 standard substance and the turbine oil sample to be detected as raw materials, prepare concentration gradient standard solutions with different T501 contents; S2. Use an infrared spectrometer to detect the absorbance of the phenolic hydroxyl stretching vibration absorption peak at a wavenumber of 3650 cm -1 for each concentration standard solution; S3. Based on the proportional relationship between the absorbance and the T501 concentration, plot the standard curve of the standard addition method to obtain the standard regression equation; S4. Extend the regression equation to the X-axis and determine the original concentration of T501 in the turbine oil sample to be detected through the intercept.
[0019] The steps for preparing the concentration gradient standard solutions are specifically as follows: Using the turbine oil sample to be detected as the solvent, add 12.5 μL, 25.0 μL, 37.5 μL, 50.0 μL, and 125.0 μL of T501 standard solution to a 25 mL volumetric flask respectively, and make up to the scale line with the turbine oil sample to be detected, and mix well.
[0020] Example 3 This example provides a method for determining the content of T501 in turbine oil based on infrared spectroscopy, as Figure 1 shown, including the following steps: S1. Using T501 standard substance and the turbine oil sample to be detected as raw materials, prepare concentration gradient standard solutions with different T501 contents; S2. Use an infrared spectrometer to detect the absorbance of the phenolic hydroxyl stretching vibration absorption peak at a wavenumber of 3650 cm -1 for each concentration standard solution; S3. Based on the proportional relationship between the absorbance and the T501 concentration, plot the standard curve of the standard addition method to obtain the standard regression equation; S4. Extend the regression equation to the X-axis and determine the original concentration of T501 in the turbine oil sample to be detected through the intercept.
[0021] The steps for preparing the concentration gradient standard solution are as follows: Using the turbine oil sample to be detected as the solvent, add 12.5 μL, 25.0 μL, 37.5 μL, 50.0 μL, and 125.0 μL of T501 standard solution into a 25 mL volumetric flask respectively, and make up the volume to the calibration line with the turbine oil sample to be detected, then mix evenly. The operation of mixing evenly after volume making-up adopts vortex oscillation or ultrasonic oscillation, and the oscillation time is 30 s to 2 min.
[0022] The preparation of the concentration gradient standard solution also includes a turbine oil sample to be detected without adding T501 standard solution, that is, add 0 mL of T501 standard solution, and make up the volume to 25 mL in a volumetric flask with the turbine oil sample to be detected.
[0023] The standard for detection using an infrared spectrometer in S2 is: the scanning range of the infrared spectrometer covers the mid-infrared region 4000 - 400 cm -1 , the scanning speed is set to 32 cm -1 -35 cm -1 , and it is equipped with a liquid absorption cell. The optical path of the liquid absorption cell is 0.1 mm to 1 mm.
[0024] Example 4 This example provides a method for determining the T501 content in turbine oil based on infrared spectroscopy, as Figure 1 shown, including the following steps: S1, Using T501 standard substance and the turbine oil sample to be detected as raw materials, prepare concentration gradient standard solutions with different T501 contents; S2, Use an infrared spectrometer to detect the absorbance of the phenolic hydroxyl stretching vibration absorption peak at a wavenumber of 3650 cm -1 for each concentration standard solution; S3, Based on the proportional relationship between the absorbance and the T501 concentration, draw the standard curve of the standard addition method to obtain the standard regression equation; S4, Extend the regression equation to the X-axis, and determine the original concentration of T501 in the turbine oil sample to be detected through the intercept.
[0025] The steps for preparing the concentration gradient standard solution are as follows: Using the turbine oil sample to be detected as the solvent, add 12.5 μL, 25.0 μL, 37.5 μL, 50.0 μL, and 125.0 μL of T501 standard solution into a 25 mL volumetric flask respectively, and make up the volume to the calibration line with the turbine oil sample to be detected, then mix evenly. The operation of mixing evenly after volume making-up adopts vortex oscillation or ultrasonic oscillation, and the oscillation time is 30 s to 2 min.
[0026] The preparation of the concentration gradient standard solution also includes a turbine oil sample to be detected without adding the T501 standard solution, that is, 0 mL of the T501 standard solution is added, and the turbine oil sample to be detected is used to make up the volume to a 25 mL volumetric flask.
[0027] The standard for detection using an infrared spectrometer in S2 is: the scanning range of the infrared spectrometer covers the mid-infrared region of 4000 - 400 cm -1 , the scanning speed is set to 32 cm -1 -35 cm -1 , and it is equipped with a liquid absorption cell. The optical path of the liquid absorption cell is 0.1 mm to 1 mm. Specifically, the standard addition method is used to draw the standard curve in S3: the content of the T501 standard substance in the turbine oil sample to be detected is used as the abscissa, and the absorbance is used as the ordinate to draw the standard curve.
[0028] Example 5 This example provides a method for determining the content of T501 in turbine oil based on infrared spectroscopy, as Figure 1 shown, including the following steps: S1, using the T501 standard substance and the turbine oil sample to be detected as raw materials, prepare concentration gradient standard solutions with different T501 contents; S2, use an infrared spectrometer to detect the absorbance of the phenolic hydroxyl stretching vibration absorption peak at a wavenumber of 3650 cm -1 for each concentration standard solution; S3, based on the proportional relationship between the absorbance and the T501 concentration, draw the standard curve of the standard addition method to obtain the standard regression equation; S4, extend the regression equation to the X-axis, and determine the original concentration of T501 in the turbine oil sample to be detected through the intercept.
[0029] Specifically, the steps for preparing the concentration gradient standard solution are as follows: using the turbine oil sample to be detected as the solvent, add 12.5 μL, 25.0 μL, 37.5 μL, 50.0 μL, and 125.0 μL of the T501 standard solution to a 25 mL volumetric flask respectively, and use the turbine oil sample to be detected to make up the volume to the scale line, and mix evenly. The operation of mixing evenly after volume fixation adopts vortex oscillation or ultrasonic oscillation, the oscillation time is 30 s to 2 min, and the oscillation can adopt vortex oscillation or ultrasonic oscillation.
[0030] Vortex oscillation can be adopted: the rotation speed is set to 2000 - 3000 revolutions per minute, and the oscillation time is 1 min.
[0031] Ultrasonic oscillation is adopted: the power is set to 300 - 500 W, the oscillation time is 1 min, and it can be carried out at room temperature to avoid the influence of sample temperature rise on the detection results.
[0032] The preparation of the concentration gradient standard solution also includes a turbine oil sample to be tested without adding the T501 standard solution, that is, 0 mL of the T501 standard solution is added, and the turbine oil sample to be tested is used to make up the volume to a 25 mL volumetric flask.
[0033] The standard for detection using an infrared spectrometer in S2 is: the scanning range of the infrared spectrometer covers the mid-infrared region of 4000 - 400 cm -1 , the scanning speed is set to 32 cm -1 -35 cm -1 , and it is equipped with a liquid absorption cell. The optical path of the liquid absorption cell is 0.1 mm - 1 mm.
[0034] In S3, the specific method for drawing the standard curve by the standard addition method is: taking the content of the T501 standard substance in the turbine oil sample to be tested as the abscissa and the absorbance as the ordinate to draw the standard curve.
[0035] In S4, the specific method for determining the original concentration of T501 in the turbine oil sample to be tested through the intercept is: extending the regression equation to intersect with the X-axis, and the X-axis value corresponding to the intersection point is the original concentration of T501 in the turbine oil sample to be tested. The detection accuracy of the absorbance of the infrared spectrometer at a wavenumber of 3650 cm -1 is within ±0.01 AU.
[0036] Example 6 This example takes the determination of the T501 content of the turbine oil of Unit 1 in a thermal power plant as an example. As Figure 1-2 shown, weighing and measurement are carried out according to the following sample preparation process and detection steps.
[0037] (1) Infrared spectrometer: Use the mid-infrared region of 4000 - 400 cm -1 , the scanning speed is 32 cm -1 , and it is equipped with a liquid absorption cell.
[0038] (2) Sample preparation: The first portion is to add 0 mL of the T501 standard solution, and use the oil sample to be tested to make up the volume to a 25 mL volumetric flask.
[0039] The second portion is to add 0.05% of the T501 standard solution. Use a pipette to transfer 12.5 μL of the T501 standard solution into 25 mL of the oil sample to be tested, and mix evenly.
[0040] The third portion is to add 0.10% of the T501 standard solution. Use a pipette to transfer 25.0 μL of the T501 standard solution into 25 mL of the oil sample to be tested, and mix evenly.
[0041] The fourth sample is to add 0.15% of the T501 standard solution. Use a pipette to transfer 37.5 μL of the T501 standard solution into 25 mL of the oil sample to be tested, and mix well.
[0042] The fifth sample is to add 0.20% of the T501 standard solution. Use a pipette to transfer 50.0 μL of the T501 standard solution into 25 mL of the oil sample to be tested, and mix well.
[0043] The sixth sample is to add 0.50% of the T501 standard solution. Use a pipette to transfer 125.0 μL of the T501 standard solution into 25 mL of the oil sample to be tested, and mix well.
[0044] In this determination process, % refers to the mass concentration of the T501 standard solution, that is, each 100 g of the standard solution contains 0.05 g, 0.10 g, etc. of the T501 additive by mass (3)Data processing: The above six samples are respectively passed through an infrared spectrometer to obtain absorbances A1~A6. Through the relationship between concentration and absorbance, the regression curve is obtained. When y = 0, the intercept is the content of T501 in the original oil sample to be tested. The content of T501 in this No. 1 main engine oil is 0.34%, and R 2 = 0.997.
[0045] In the above embodiments, the material of the liquid absorption cell is sodium chloride or potassium bromide, which is suitable for detection in the mid-infrared region (4000 - 400 cm -1 ), and it needs to be wiped clean with anhydrous ethanol or acetone before use to ensure that the cell window is transparent and free of stains.
Claims
1. A method for determining the content of T501 in turbine oil based on infrared spectrometry, characterized in that, Specifically, it includes the following steps: S1. Using T501 reference material and the turbine oil sample to be tested as raw materials, prepare concentration gradient standard solutions with different T501 contents; S2, use an infrared spectrometer to detect the absorbance of the stretching vibration absorption peak of phenolic hydroxyl groups at a wavenumber of 3650 cm -1 for each concentration standard solution; S3. Based on the proportional relationship between absorbance and T501 concentration, plot the standard curve of the standard addition method to obtain the standard regression equation; S4. Extend the regression equation to the X-axis and determine the original concentration of T501 in the turbine oil sample to be tested through the intercept.
2. The method for determining the content of T501 in turbine oil based on infrared spectrometry according to claim 1, wherein The specific steps for preparing the concentration gradient standard solutions are as follows: Using the turbine oil sample to be tested as the solvent, add 12.5 μL, 25.0 μL, 37.5 μL, 50.0 μL, and 125.0 μL of T501 standard solution to a 25 mL volumetric flask respectively, and make up to the calibration line with the turbine oil sample to be tested, then mix evenly.
3. The method for determining the content of T501 in turbine oil based on infrared spectroscopy according to claim 1, characterized in that, For the operation of mixing evenly after volume fixation, vortex oscillation or ultrasonic oscillation is used, and the oscillation time is 30 s to 2 min.
4. The method for determining the content of T501 in turbine oil based on infrared spectrometry according to claim 1, wherein, The preparation of the concentration gradient standard solutions also includes a turbine oil sample to be tested without adding T501 standard solution, that is, adding 0 mL of T501 standard solution and making up to 25 mL in a volumetric flask with the turbine oil sample to be tested.
5. The method for determining the content of T501 in turbine oil based on infrared spectroscopy according to claim 1, wherein The standard for detection using an infrared spectrometer described in S2 is that the scanning range of the infrared spectrometer covers the mid-infrared region of 4000-400 cm -1 , the scanning speed is set to 32 cm -1 -35 cm -1 , and it is equipped with a liquid absorption cell.
6. The method for determining the content of T501 in turbine oil based on infrared spectroscopy according to claim 4, characterized in that, The optical path of the liquid absorption cell is 0.1 mm to 1 mm.
7. The method for determining the content of T501 in turbine oil based on infrared spectrometry according to claim 1, wherein The specific method for plotting the standard curve using the standard addition method in S3 is as follows: Plot the standard curve with the content of T501 reference material in the turbine oil sample to be tested as the abscissa and absorbance as the ordinate.
8. The method for determining the content of T501 in turbine oil based on infrared spectroscopy according to claim 1, wherein, The specific method for determining the original concentration of T501 in the turbine oil sample to be tested through the intercept in S4 is as follows: Extend the regression equation to intersect with the X-axis, and the X-axis value corresponding to the intersection point is the original concentration of T501 in the turbine oil sample to be tested.
9. The method for determining the content of T501 in turbine oil based on infrared spectrometry according to claim 1, characterized in that, The absorbance detection accuracy of the infrared spectrometer at 3650 cm ⁻¹ wave number is within ±0.01 AU.