Analysis method for chromaticity and paint film index of fire-resistant oil in power plant

Abstract

The invention belongs to the technical field of chemical analysis of nuclear power plants, and particularly relates to a power plant fire-resistant oil chromaticity and paint film index analysis method which comprises the following steps: step 1, preparing a preparation solution, and preparing a standard colorimetric solution with chromaticity No. 1-25 by using the preparation solution according to the standard of Petroleum Product Chromaticity Determination Method; 2, setting measurement parameters of a spectrophotometer, and measuring the absorbance of the standard colorimetric solution by using the spectrophotometer; and step 3, fitting the absorbance and the chromaticity of the standard colorimetric solution according to a measurement result in the step 2 to obtain a standard curve equation of the chromaticity and the absorbance of the standard colorimetric solution. 4, measuring the chromaticity and the paint film index of the fire-resistant oil sample, and formulating a standard for judging the paint film index through the chromaticity and the absorbance; and 5, measuring the absorbance and chromaticity of the fire-resistant oil to be measured, and judging whether the paint film index exceeds the standard or not according to the standard in the step 4. The application of the invention can save economic cost, reduce outgoing detection frequency, and reduce unnecessary loss and labor cost.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical analysis of nuclear power plants, and in particular relates to an analysis method for the chromaticity and paint film index of fire-resistant oil in power plants. Background Art

[0002] The turbine regulating oil system is used to provide high-pressure fire-resistant oil to the turbine and drive the servo actuator to open and control the steam valves of the turbine. In the actual operation of the power plant, since some circuits of the turbine regulating oil system are in a high-temperature and overheated environment, after a period of operation, the fire-resistant oil inside will become darker in color, increase in acidity, and decompose faster. In addition, as a hydrocarbon, the fire-resistant oil will undergo thermal cracking, resulting in the breakage of its molecular chain, severe aging of the oil, and even carbonization. Degraded fire-resistant oil will cause problems such as corrosion and blockage of the servo valve, thereby affecting the safety and reliability of turbine operation.

[0003] The deterioration of fire-resistant oil quality will accelerate the corrosion and erosion of the turbine regulating oil system, which may cause leakage, servo valve wear, sticking, unstable operating pressure, valve loss of control, slow or swinging valve movement, and oil motor refusal to move. These problems will have a direct impact on the operating reliability and safety of the turbine regulating oil system.

[0004] In summary, chemical supervision and control of the turbine regulating oil system is an effective way to reduce operational failures or equipment failures caused by oil quality problems. Among them, the color of the fire-resistant oil in power plants, the film tendency index (hereinafter referred to as the film index) and other parameters are important parameters in the quality control of fire-resistant oil. However, the traditional method of measuring the color and film index of fire-resistant oil is cumbersome, time-consuming, and has large errors in the measurement results. Summary of the invention

[0005] Aiming at the problems that the prior art method for measuring the chromaticity and film index of fire-resistant oil is complicated, time-consuming and has large measurement error, the present invention provides an analysis method for the chromaticity and film index of fire-resistant oil in a power plant.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention proposes a method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant, characterized in that the method comprises:

[0008] Step 1: Prepare the prepared solution to be prepared into a colorimetric solution according to the preparation method of the standard color chip colorimetric solution in the "Colorimetric Determination of Petroleum Products" to prepare a standard colorimetric solution with a chromaticity of 1-25;

[0009] Step 2: Setting the measurement parameters of the spectrophotometer, and measuring the absorbance of the standard colorimetric solution using the spectrophotometer;

[0010] Step 3: According to the measurement result of step 2, the absorbance and chromaticity of the standard colorimetric solution are fitted to obtain a standard curve equation of the chromaticity and absorbance of the standard colorimetric solution.

[0011] Step 4: Measure the chromaticity and film index of fire-resistant oil samples, and formulate a standard for judging the film index by chromaticity and absorbance;

[0012] Step 5: Measure the absorbance and chromaticity of the fire-resistant oil to be tested, and determine whether the paint film index exceeds the standard according to the standard of step 4.

[0013] In some embodiments, the step 2 of measuring the absorbance of the standard colorimetric solution using a spectrophotometer includes: pouring the standard colorimetric solutions with a chromaticity of 1-25 in step 1 one by one into a 1 cm quartz cuvette for scanning measurement, and obtaining a wavelength scanning curve graph of the standard colorimetric solution by the spectrophotometer, wherein the horizontal coordinate of the wavelength scanning curve graph of the standard colorimetric solution is the wavelength, and the vertical coordinate is the absorbance; the vertical coordinate range of the standard colorimetric curve graph is set to 0-1.0.

[0014] In some embodiments, in step 2, the absorbance of the standard colorimetric solution is measured by a spectrophotometer, and standard colorimetric solutions No. 1-5 have a strong absorption peak at a wavelength of 350nm, and the absorbance of standard colorimetric solutions No. 1-5 at a wavelength of 350nm is recorded; the absorbance of standard colorimetric solutions No. 1-14 at a wavelength of 450nm is recorded, and the absorbance of standard colorimetric solutions No. 15-25 at a wavelength of 620nm is recorded.

[0015] In some embodiments, in step three, the absorbance and chromaticity of the standard colorimetric solution are fitted, the standard colorimetric solution with a chromaticity of 1-14 is selected, and the absorbance and chromaticity of the standard colorimetric solution at 450 nm are selected for fitting.

[0016] In some embodiments, the standard curve equation in step 3 is specifically formula (1);

[0017] y = 18.293x3 - 39.008x2 + 33.178x + 1.3333 (1)

[0018] Among them, x is the absorbance value and y is the chromaticity.

[0019] In some embodiments, the standard for determining the paint film index by chromaticity and absorbance in step 4 is that the chromaticity of the fire-resistant oil is less than or equal to 9, and the absorbance of the fire-resistant oil is less than or equal to 0.381, which means that the oil quality has deteriorated and needs to be purified.

[0020] In some embodiments, setting the spectrophotometer measurement parameters in step 2 specifically includes: setting the wavelength scanning range of the spectrophotometer to 1000-320nm, the scanning accuracy to 1nm, the slit width to 2, and using deionized water as the reference solution.

[0021] In some embodiments, the standard colorimetric solution of step 1 is stored in a dark place at 25°C ± 3°C and has a shelf life of one week.

[0022] The implementation of the present invention has the following beneficial effects:

[0023] The present invention aims at the deficiencies existing in the quality determination of fire-resistant oil in power plants, and establishes an analysis method for the chromaticity and paint film index of fire-resistant oil in power plants. The implementation of the present invention has the following advantages:

[0024] 1. The present invention adopts spectrophotometry to measure the chromaticity of fire-resistant oil. This method can convert the measured absorbance value into chromaticity through a curve graph and a curve equation. Compared with the previous visual colorimetry and colorimeter method, it is more accurate and convenient; the measurement time is short, which not only improves the accuracy and sensitivity of the measurement, but also eliminates the visual error of different measurers, and at the same time saves the tedious steps of regularly preparing standard colorimetric solutions to calibrate colorimetric cards and replacing colorimetric cards. The standard curve can be used for a long time as long as it is calibrated regularly, and the SH color number and ISO (GB) color number can be obtained at the same time.

[0025] 2. The present invention measures the chromaticity and film index of fire-resistant oil samples, formulates a standard for judging the film index by chromaticity and absorbance, and compares the three data of absorbance, chromaticity, and film index MPC of fire-resistant oil. It is found that the higher the absorbance, the higher the chromaticity, and the higher the film index MPC. Finally, it is determined that the chromaticity of 9 (i.e., the absorbance measured by the spectrophotometer is ≤0.381) is used as the dividing line to monitor and control the fire-resistant oil, so as to better control the quality of the fire-resistant oil by chromaticity, and achieve the purpose of accurately and quickly discovering the deterioration of the fire-resistant oil.

[0026] 3. The present invention is not only applicable to the determination of the chromaticity of fire-resistant oil, but also to the determination of the chromaticity of water quality, lubricating oil and fuel oil. The change of the paint film index MPC can be reflected by the chromaticity. It is a pioneering integration of chemical measurement technology innovation and chemical control optimization research. Through the optimization of chemical control, the oil quality deterioration trend can be judged more quickly, and preventive measures can be taken in advance to reduce the unit's operating failures or equipment failures caused by oil quality problems.

[0027] 4. The application of the present invention can save economic costs. During the period of oil quality deterioration and oil quality purification, the frequency of external inspection can be reduced, and unnecessary filter element loss and labor costs can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A wavelength scanning curve diagram of a standard colorimetric solution for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant proposed in an embodiment of the present invention;

[0029] Figure 2 A wavelength scanning curve diagram of fire-resistant oil of a method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant proposed in an embodiment of the present invention;

[0030] Figure 3 The present invention provides a method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant, which is a graph of the chromaticity and absorbance of 1-14 standard colorimetric solutions at a wavelength of 450nm. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figures 1 to 3 As shown, the present invention proposes a method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant, the method comprising:

[0033] Step 1: Prepare the preparative solution. Use the preparative solution to prepare a standard colorimetric solution of SH color 1-25 according to the standard "Colorimetric Determination of Petroleum Products".

[0034] In this step, the preparation solution is first prepared, including:

[0035] Preparation of 1% sulfuric acid (H2SO4) solution: Accurately pipette 20 mL of sulfuric acid and slowly pour it into 1980 mL of deionized water, shake well and set aside.

[0036] Preparation of 10% hydrochloric acid (HCL) solution: Accurately pipette 100 mL of hydrochloric acid and slowly add it into 900 mL of deionized water, shake well and set aside.

[0037] Preparation of 1g / L potassium dichromate (K2Cr2O7) solution: weigh 0.5g potassium dichromate, dissolve it in 1% sulfuric acid solution, then transfer it to a 500mL volumetric flask, add high-purity water to make up to volume for later use.

[0038] Preparation of 500 g / L cobalt sulfate (CoSO4·7H2O) solution: Weigh 50 g of cobalt sulfate, dissolve it in 1% sulfuric acid solution, then transfer it to a 100 mL volumetric flask, add high-purity water to make up to volume for later use.

[0039] Preparation of 500g / L ferric chloride (FeCl3·6H2O) solution: Weigh 250g of ferric chloride, dissolve it in 10% sulfuric acid solution, then transfer it to a 500mL volumetric flask, add high-purity water to make up to volume for later use.

[0040] Preparation of 3g / L ammonium thiocyanate (NH4CNS) solution: weigh 0.3g of solid ammonium thiocyanate, dissolve it with high-purity water, then transfer it to a 100mL volumetric flask and add high-purity water to make up to volume for later use.

[0041] After preparing the above-mentioned preparatory solutions, refer to the preparation method of colorimetric solutions used as calibration standard color chips in "Petroleum Product Colorimetric Determination Method" (SH / T 0168-1992), take the above-mentioned reagents, measure the volumes of various solutions according to Table 1, and prepare standard colorimetric solutions corresponding to each chromaticity. For example, to prepare colorimetric solution of chromaticity 1, measure 0.40mL of potassium dichromate solution to a 50mL volumetric flask, then measure 49.6mL of sulfuric acid solution, shake well, and the preparation is complete. The above-mentioned standard colorimetric solutions must be stored in a dark place at 25℃±3℃, and the validity period is one week.

[0042] Table 1 Standard colorimetric solution configuration table Unit: mL

[0043]

[0044] Note: “---” means that this solution is not added to this color.

[0045] Step 2: Set the spectrophotometer measurement parameters and use the spectrophotometer to measure the absorbance of the standard colorimetric solution.

[0046] The wavelength scanning range of the PerkinElmer Lambda35 spectrophotometer was set to 1000nm-320nm, the scanning accuracy was 1nm, and the slit width was 2nm. Deionized water was used as the reference solution. Standard colorimetric solutions with a chromaticity of 1-25 were poured into a 1cm quartz cuvette one by one for scanning measurement. A wavelength scanning curve of the standard colorimetric solution with the abscissa being the wavelength and the ordinate being the absorbance was obtained, as shown in FIG. Figure 1 shown.

[0047] The ordinate range of the standard colorimetric curve is set at 0-1.0. In this embodiment, Figure 1As shown, the No. 1-5 standard colorimetric solution has a strong absorption peak at a wavelength of 350nm, and the absorbance of the No. 1-5 standard colorimetric solution at a wavelength of 350nm is recorded; the No. 6-25 standard colorimetric solution has no absorption peak, so the wavelength at which the absorbance is stable and the curves can be clearly separated is selected to record the absorbance. In addition, since the composition of the No. 15-25 standard colorimetric solution is obviously different from that of the No. 1-14 standard colorimetric solution, and the ISO (GB) chromaticity corresponding to the No. 14 and No. 15 standard colorimetric solutions is No. 3, the No. 6-14 standard colorimetric solution is selected into a group, and the absorbance at a wavelength of 450nm is recorded, and the No. 15-25 standard colorimetric solution records the absorbance at a wavelength of 620nm. See Table 2 for specific data.

[0048] Table 2 Comparison of absorbance A and chromaticity at different absorption wavelengths

[0049]

[0050]

[0051] Note: The comparison between SH chromaticity and GB / T6540 chromaticity (ISO chromaticity) comes from SH / T0168-92.

[0052] Step 3: According to the measurement results of step 2, the absorbance and chromaticity of the standard colorimetric solution are fitted to obtain the standard curve equation of the chromaticity and absorbance of the standard colorimetric solution.

[0053] In actual testing, wavelength scanning is performed on the fuel oil. Figure 2 As shown, the horizontal axis is wavelength and the vertical axis is absorbance. It can be seen that the fire-resistant oil has a large absorption interference at a wavelength less than 380nm, that is, in the area of ​​ultraviolet light and near ultraviolet light, so the data in Table 2 cannot be used directly. At the same time, the results measured at a wavelength of 620nm have far exceeded the limit of the power plant's color index for fire-resistant oil. Therefore, for the determination of fire-resistant oil color, the absorbance of standard colorimetric solutions No. 1-5 was re-measured at a wavelength of 450nm and recorded, and finally the absorbance of standard colorimetric solutions No. 1-14 was measured at a wavelength of 450nm. We do not make statistics on the data at 620nm, and the results are shown in Table 3 below.

[0054] Table 3 Absorbance and chromaticity correspondence of 1-14 standard colorimetric solutions at a wavelength of 450nm

[0055]

[0056]

[0057] The data was processed and the chromaticity and absorbance curves of the standard colorimetric solution were fitted as shown in Figure 3 As shown, the standard curve equation is obtained as formula (1);

[0058] y = 18.293x3 - 39.008x2 + 33.178x + 1.3333 (1)

[0059] Among them, x is the absorbance value and y is the chromaticity. The measured absorbance value can be converted into chromaticity through the curve graph and curve equation, which is more accurate and convenient than the previous visual colorimetry and colorimeter method.

[0060] Step 4: Measure the chromaticity and film index of fire-resistant oil samples, and formulate a standard for judging the film index by chromaticity and absorbance;

[0061] In order to study the relationship between the chromaticity of fire-resistant oil and the paint film index MPC, the chromaticity and paint film index MPC of fire-resistant oil samples of multiple nuclear power station units were measured. The specific measurement data are shown in Table 4.

[0062] Table 4 Fire-resistant oil test data

[0063]

[0064]

[0065] By comparing the three data of anti-fuel oil absorbance, chromaticity, and paint film index MPC, it can be found that the higher the absorbance, the higher the chromaticity, and the higher the paint film index MPC. When the oil paint film index MPC is above 29.8, the SH chromaticity is ≥10 and the absorbance is ≥0.392; when the SH chromaticity is 9, the paint film index MPC is the highest at 21.5 and the absorbance is ≤0.316.

[0066] At present, the quality control index of the MPC value of fire-resistant oil in power plants is <30. Based on the data in Table 4 and the corresponding relationship between the absorbance and chromaticity of the standard colorimetric solution at 450nm of the spectrophotometer, it is concluded that when the chromaticity of the oil product is close to 10 or the absorbance is >0.381, it is necessary to pay close attention to the paint film index, at which time the oil quality is likely to have seriously deteriorated. It is recommended that during the oil quality control or oil purification process, the color number of the fire-resistant oil should be ensured to be ≤9, that is, the absorbance measured by the spectrophotometer is ≤0.381.

[0067] Step 5: Measure the absorbance and color of the fire-resistant oil to be tested, and determine whether the paint film index exceeds the standard according to the standard of step 4.

[0068] The present invention proposes an analysis method for the chromaticity and paint film index of fire-resistant oil in a power plant. Taking the fire-resistant paint film index MPC of a nuclear power unit exceeding the control limit and taking oil purification measures as an example, the effect of implementing this method is as follows:

[0069] After the MPC index of the fire-resistant paint film of the nuclear power unit exceeds the control limit, the regeneration filter element and filter components including the fine filter and the coarse filter are put into operation to filter the oil. The oil filtering is uninterrupted 24 hours a day, and the cumulative oil filtering time is about 168 hours. During the oil filtering period, a set of regeneration filter elements is replaced every 72 hours. During the oil filtering period, samples are taken every day for analysis of moisture, acid value, resistivity and the samples are retained. After each filter element change, samples are taken for outsourcing analysis of MPC. During this oil filtering period, the oil quality analysis was also performed using this method. The results of the oil quality sampling and analysis during this oil filtering period are shown in Table 5.

[0070] Table 5 Oil quality test results during oil filtration of fire-resistant oil

[0071]

[0072]

[0073] In the past, after major or minor repairs at power plants or when the oil quality was abnormal, the fire-resistant fuel was purified. In addition to routine analysis and testing such as moisture, particle size and acid value during the oil purification and filtration process, the purification effect is often judged by observing the appearance and color of the oil. For example, if the color becomes significantly lighter and transparent, it means that the oil filtration effect is obvious. However, there was a lack of a specific and accurate measurement result reference for the purification efficiency of the filter element and when the purification was completed. For purification of paint film index exceeding the standard, it often takes a long time to get feedback after the sample is sent out for inspection. Through the colorimetric measurement of this method, the oil purification situation can be quickly obtained, which can be used to assist in judging the purification efficiency and filter effect.

[0074] In this oil purification, by using the measurement method proposed by the present invention, it is statistically predicted that the purification can be stopped when the flame retardant paint film index MPC is between 17 and 20 after purification for 167 hours. After continuous oil filtration for 144 hours, according to the oil filtration plan, a new filter element should be replaced. By judging from the color change trend of the oil product and the comparison relationship between the color and the paint film index, the filter element still has a certain purification capacity, and it is suggested not to replace the filter element temporarily, which reduces unnecessary filter element replacement and saves oil filtration time and cost.

[0075] One week after the oil purification was completed, the MPC results of the paint film index obtained by the outsourcing test were consistent with the MPC predicted by the color measurement. This method proves that the method can accurately and quickly judge the purification effect of fire-resistant oil, and provides data support for the judgment of purification efficiency and the loss degree of the filter element of the oil filter.

[0076] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. A method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant, characterized in that: The method comprises: Step 1: Prepare the prepared solution to be prepared into a colorimetric solution according to the preparation method of the standard color chip colorimetric solution in the "Colorimetric Determination of Petroleum Products" to prepare a standard colorimetric solution with a chromaticity of 1-25; Step 2: Setting the measurement parameters of the spectrophotometer, and measuring the absorbance of the standard colorimetric solution using the spectrophotometer; Step 3: According to the measurement result of step 2, the absorbance and chromaticity of the standard colorimetric solution are fitted to obtain a standard curve equation of the chromaticity and absorbance of the standard colorimetric solution. Step 4: Measure the chromaticity and film index of fire-resistant oil samples, and formulate a standard for judging the film index by chromaticity and absorbance; Step 5: Measure the absorbance and chromaticity of the fire-resistant oil to be tested, and determine whether the paint film index exceeds the standard according to the standard of step 4.

2. The method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant according to claim 1, characterized in that: The step 2 of using a spectrophotometer to measure the absorbance of the standard colorimetric solution includes: pouring the standard colorimetric solutions with a chromaticity of 1-25 in step 1 one by one into a 1 cm quartz cuvette for scanning measurement, and obtaining a wavelength scanning curve of the standard colorimetric solution by the spectrophotometer, wherein the abscissa of the wavelength scanning curve of the standard colorimetric solution is the wavelength, and the ordinate is the absorbance; the ordinate range of the standard colorimetric curve is set at 0-1.

0.

3. The method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant according to claim 1, characterized in that: In the step 2, the absorbance of the standard colorimetric solution is measured by a spectrophotometer. The standard colorimetric solutions No. 1-5 have a strong absorption peak at a wavelength of 350nm, and the absorbance of the standard colorimetric solutions No. 1-5 at a wavelength of 350nm is recorded; the absorbance of the standard colorimetric solutions No. 1-14 at a wavelength of 450nm is recorded, and the absorbance of the standard colorimetric solutions No. 15-25 at a wavelength of 620nm is recorded.

4. The method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant according to claim 1, characterized in that: In the step three, the absorbance and chromaticity of the standard colorimetric solution are fitted, the standard colorimetric solution with a chromaticity of 1-14 is selected, and the absorbance and chromaticity of the standard colorimetric solution at 450nm are selected for fitting.

5. The method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant according to claim 2, characterized in that: The standard curve equation in step 3 is specifically formula (1); y = 18.293x 3 - 39.008x 2 + 33.178x + 1.3333 (1) Among them, x is the absorbance value and y is the chromaticity.

6. The method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant according to claim 1, characterized in that: The standard for determining the paint film index by chromaticity and absorbance in step 4 is that the chromaticity of the fire-resistant oil is less than or equal to 9, and the absorbance of the fire-resistant oil is less than or equal to 0.381, which means that the oil quality is deteriorated and needs to be purified.

7. The method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant according to claim 5, characterized in that: The step 2 of setting the spectrophotometer measurement parameters specifically includes: setting the wavelength scanning range of the spectrophotometer to 1000nm-320nm, the scanning accuracy to 1nm, the slit width to 2nm, and the reference solution to deionized water.

8. The method for analyzing the chromaticity and paint film index of fire-resistant oil in a power plant according to claim 1, characterized in that: The standard colorimetric solution in step 1 is stored in a dark place at a temperature of 25°C ± 3°C and has a validity period of one week.

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