Quality evaluation method for fire-resistant oil of main steam isolation valve of nuclear power plant

Abstract

The invention relates to the technical field of nuclear power plant oil product control, in particular to a nuclear power plant main steam isolation valve fire-resistant oil quality evaluation method. The quality evaluation method provided by the invention comprises the following steps: taking used fire-resistant oil samples with different acid values in a plurality of main steam isolation valves; adding different proportions of unused fire-resistant oil into the used fire-resistant oil sample to obtain a plurality of mixed oil samples; carrying out aging treatment on the mixed oil sample, monitoring the acid value of the mixed oil sample until the mixed oil sample is aged for at least 30 days, and stopping aging after the acid value of each aged mixed oil sample exceeds 9mgKOH / g; and evaluating the quality of the used fire-resistant oil sample according to the increasing trend of the acid value of the mixed oil sample along with the aging time. According to the method, the change condition of the fire-resistant oil product of the main steam isolation valve can be analyzed according to the increasing trend of the acid value of the mixed oil sample, and data support is provided for whether the fire-resistant oil is continuously used or not, so that safe operation of equipment is better facilitated.

Description

Technical Field

[0001] The present application belongs to the technical field of oil product control in nuclear power plants, and in particular to a quality assessment method for anti-oil of a main steam isolation valve in a nuclear power plant. Background Art

[0002] A pressurized water reactor nuclear power plant is mainly composed of a nuclear steam supply system (i.e., primary circuit system), a steam turbine generator system (i.e., secondary circuit system), and other auxiliary systems. The main steam isolation valve is a nuclear safety-grade valve used in the secondary circuit main steam system (VVP) of a pressurized water reactor nuclear power plant. It is mainly arranged on the top of nuclear safety-related buildings and electrical buildings, outside the containment, and is one of the major key equipment in a nuclear power plant. The main function of the main steam isolation valve is to provide containment isolation for the main steam pipeline, prevent overpressure in the containment caused by the rupture of the main steam pipeline, and limit the cooling of the main system caused by the rupture of the steam pipeline or the main feedwater pipeline; at the same time, it prevents the radioactive medium in the primary circuit from spreading to the secondary circuit after the rupture of the steam generator heat transfer tube.

[0003] The oil used in the main steam isolation valve is fire-resistant oil, which has the advantages of flame retardancy, good wear resistance, and stable physical properties. Due to the importance of the main steam isolation valve, the quality of the fire-resistant oil used in it needs to be reasonably monitored. At present, there is no clear monitoring standard for the oil quality of the main steam isolation valve. It is only monitored by referring to the operating oil standard of the turbine speed control system. However, due to the different conditions of the two, the reference effect is limited. In order to ensure the long-term safe operation of the equipment, the oil quality of the main steam isolation valve during operation must be reasonably regulated and controlled. A quality assessment method for the main steam isolation valve fire-resistant oil that conforms to the actual production on site is needed. Summary of the invention

[0004] The purpose of this application is to provide a quality assessment method for the fire-resistant oil of the main steam isolation valve of a nuclear power plant, aiming to solve the technical problem of how to better assess the quality of the fire-resistant oil of the main steam isolation valve of a nuclear power plant so as to provide early warning and improve the safety of equipment operation.

[0005] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0006] The present application provides a method for evaluating the quality of fire-resistant oil of a main steam isolation valve of a nuclear power plant, comprising:

[0007] Take used fire-resistant oil samples with different acid values ​​from multiple main steam isolation valves;

[0008] adding unused fire-resistant oil in different proportions to the used fire-resistant oil sample to obtain a plurality of mixed oil samples;

[0009] Performing an aging treatment on the mixed oil sample and monitoring the acid value of the mixed oil sample until the aging is at least 30 days and the acid value of each of the mixed oil samples exceeds 9 mgKOH / g after aging, then stopping the aging;

[0010] The quality of the fire-resistant oil after use is evaluated based on the increasing trend of the acid value of the mixed oil sample with the aging time.

[0011] The quality assessment method of the fire-resistant oil of the main steam isolation valve of a nuclear power plant provided in the present application will perform aging treatment on multiple mixed oil samples obtained by mixing the used fire-resistant oil samples in the main steam isolation valve with unused fire-resistant oil, and monitor the acid value of the aging process, and evaluate the quality of the used fire-resistant oil according to the growing trend of the acid value of the mixed oil samples with the aging time. The process can analyze the changes in the fire-resistant oil quality of the main steam isolation valve according to the growing trend of the acid value of the mixed oil samples, and provide data support for whether the fire-resistant oil should continue to be used. In this way, early warning can be made, the oil change standard can be clarified, work efficiency can be improved, and cost waste can be reduced, thereby better facilitating the safe operation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 The present invention is a graph showing the trend of the acid value of the used fire-resistant oil sample with an acid value of 1.19 mgKOH / g and the acid value of the mixed oil sample after adding different proportions of unused fire-resistant oil to the sample as a function of aging time;

[0014] Figure 2 The present invention is a graph showing the trend of the acid value of the mixed oil sample after adding different proportions of unused fire-resistant oil to the used fire-resistant oil sample with an acid value of 0.32 mgKOH / g as a function of aging time;

[0015] Figure 3 The present invention is a graph showing the trend of the acid value of the mixed oil sample after adding different proportions of unused fire-resistant oil to the used fire-resistant oil sample with an acid value of 8.01 mgKOH / g as a function of aging time;

[0016] Figure 4 This is a graph showing the trend of the acid value of the used fire-resistant oil sample with an acid value of 6.89 mgKOH / g as a function of the aging time after adding different proportions of unused fire-resistant oil to the mixed oil sample in the embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0018] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0019] In the present application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0020] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0021] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0022] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0023] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0024] Since the operation of the pressurized water reactor nuclear power units in the nuclear power base, there has been no clear monitoring standard for the quality of the anti-oil oil used in the main steam isolation valve. The monitoring is only carried out with reference to the operating oil standards of the turbine speed control system. However, due to the different conditions of the two, it is difficult to provide good guidance for the use of the anti-oil oil used in the main steam isolation valve.

[0025] Because the temperature of the main steam isolation valve is high and the system itself has no oil purification device, it is very easy to cause the main steam isolation valve fire-resistant oil to age. During the operation of a nuclear power base unit, floccules appeared in the main steam isolation valve fire-resistant oil, so the quality of the fire-resistant oil was difficult to meet the requirements. After the equipment was dismantled, it was found that the copper sleeve, large piston and other parts were corroded on the surface, causing the high-pressure filter at the pump outlet to be blocked; once the high-pressure filter loses its filtering function, the deteriorated fire-resistant oil will directly enter the entire oil system, which will affect the reliability of each component inside the equipment, thereby threatening the safe operation of the unit. Because it is difficult to sample and analyze the oil quality of the main steam isolation valve fire-resistant oil during the daily operation of the unit, once the oil quality is found to be unqualified during the overhaul inspection, it is necessary to change the oil during the overhaul. During the overhaul, the oil change often needs to cope with the pressure of the construction period, and it also requires a lot of manpower, time and oil costs. Therefore, the oil quality of the main steam isolation valve fire-resistant oil needs to be reasonably monitored to facilitate the safe operation of the equipment.

[0026] Based on this, the embodiment of the present application provides a quality assessment method for the fire-resistant oil of the main steam isolation valve of a nuclear power plant, which provides key support for the unit decision-making of the nuclear power plant, and through early warning analysis of the fire-resistant oil of the main steam isolation valve, clarifies the oil change standard, improves the work efficiency during the overhaul, and reduces the cost. The specific technical solution is as follows.

[0027] The present application embodiment provides a method for evaluating the quality of fire-resistant oil of a main steam isolation valve of a nuclear power plant. Specifically, the quality evaluation method of the present application embodiment includes:

[0028] S01: Take used fire-resistant oil samples with different acid values ​​from multiple main steam isolation valves;

[0029] S02: adding different proportions of unused fire-resistant oil to the used fire-resistant oil sample to obtain multiple mixed oil samples;

[0030] S03: subjecting the mixed oil samples to aging treatment and monitoring the acid value of the mixed oil samples until the aging is at least 30 days and the acid value of each mixed oil sample exceeds 9 mgKOH / g after aging, then the aging is stopped;

[0031] S04: Evaluate the quality of fire-resistant oil after use based on the growth trend of the acid value of the mixed oil sample with aging time.

[0032] It should be noted that the various terms mentioned in the quality assessment method of the embodiment of the present application are explained as follows.

[0033] "Anti-oil" is a kind of artificial synthetic oil with low volatility, good wear resistance and stable physical properties. It is generally composed of phosphate ester liquid. Flame retardancy is one of its most prominent characteristics. It is generally used in electro-hydraulic control systems of power plants. The embodiment of this application is to evaluate the quality of anti-oil used in the main steam isolation valve of a nuclear power plant.

[0034] "Used fire-resistant oil sample" refers to the fire-resistant oil sample taken from the main steam isolation valve after the nuclear power plant unit is in operation, that is, the old fire-resistant oil that has been in operation. The embodiment of the present application analyzes multiple main steam isolation valve oil samples, which have different acid values. They can be main steam isolation valve oil samples of the same unit or different units. It is necessary to find used fire-resistant oil samples with different acid values ​​to facilitate the subsequent configuration of multiple mixed oil samples for analysis.

[0035] "Unused fire-resistant oil" refers to the fire-resistant oil sample that has not been loaded into the main steam isolation valve, that is, new fire-resistant oil that has not been put into operation. It can be synthetic fire-resistant oil for standby use or newly purchased fire-resistant oil for standby use.

[0036] "Mixed oil sample" refers to the mixed oil sample obtained by mixing the above-mentioned used fire-resistant oil sample with a certain proportion of unused fire-resistant oil, and subsequently analyzing the trend of its acid value with aging time. Among them, when the aging treatment is performed later, adding 0% of unused fire-resistant oil (i.e. no new fire-resistant oil is added) and adding 100% of unused fire-resistant oil (i.e. replacing all used fire-resistant oil samples with new fire-resistant oil) can be used as special cases of mixed oil samples for aging treatment and acid value analysis.

[0037] "Acid value" refers to the number of milligrams of potassium hydroxide (KOH) required to neutralize 1 gram of a chemical substance. It is a measurement standard for the number of free carboxylic acid groups in a compound or mixture, and is usually used to measure the acidic components in materials such as grease, lubricating oil, and plastic. The sample in the embodiment of this application is a fire-resistant oil, and its acid value test method refers to the national standard GB / T264 "Determination of Acid Value of Petroleum Products".

[0038] The quality assessment method of the embodiment of the present application first obtains a plurality of used fire-resistant oil samples with different acid values, then adds unused fire-resistant oil in different proportions to obtain a plurality of mixed oil samples, and ages the mixed oil samples until they are aged for at least 30 days and the acid value of each mixed oil sample exceeds 9 mgKOH / g, then the aging is stopped, and the relationship between the growth trend of the acid value of the mixed oil sample and the aging time is analyzed, so that the quality of the used fire-resistant oil can be evaluated, and the changes in the fire-resistant oil quality of the main steam isolation valve are analyzed through the growth trend of the acid value of the mixed oil sample, so as to provide data support for whether the fire-resistant oil should continue to be used, so that early warning can be made, the oil change standard can be clarified, the work efficiency can be improved, the cost waste can be reduced, and the safe operation of the equipment can be better facilitated.

[0039] The applicant subsequently used the above-mentioned quality assessment method during the overhaul of the nuclear power plant. By sampling and testing the oil products in the main steam isolation valve, the analysis results showed that the quality of the fire-resistant oil products of the VVP main steam isolation valve could be well controlled, ensuring that the oil products were not prone to the formation of flocs during daily operation, thereby reducing the degree of oil degradation.

[0040] Step S01: Preparation of fire-resistant oil samples after use.

[0041] Multiple used fire-resistant oil samples can be the main steam isolation valve fire-resistant oil samples of the same unit or different units. It is necessary to ensure that the acid value of each used fire-resistant oil sample is different, so as to facilitate the configuration of samples for subsequent aging tests. For example, a nuclear power base has multiple pressurized water reactor nuclear power units, each unit has 3 main steam isolation valves, and used fire-resistant oil samples with different acid values ​​can be found from these different main steam isolation valves.

[0042] In some embodiments, the oil performance of the main steam isolation valve generally changes after one fuel cycle. In order to explore the law of acid value growth and change of the main steam isolation valve fire-resistant oil, a detailed experimental plan is formulated to conduct an aging test on the main steam isolation valve fire-resistant oil that has been used for one fuel cycle to determine the service life of the oil and ensure that the oil quality will not continue to deteriorate in the next fuel cycle. This will enable the equipment to operate safely for a longer period of time and better regulate oil quality detection and quality control during operation.

[0043] Among them, one fuel cycle refers to the time from the completion of fuel replacement and the start of power generation of the nuclear power plant unit to the next shutdown for fuel replacement. The nuclear fuel replacement of a nuclear power plant unit is currently carried out about once every 18 months, and then the unit is shut down for maintenance during the window of nuclear fuel replacement, so one fuel cycle is about 18 months. Taking one fuel cycle as an example, through the analysis and statistics of the oil test data results of the VVP main steam isolation valve fire-resistant oil in each overhaul, the oil performance of the VVP main steam isolation valve fire-resistant oil changes after one fuel cycle. At the same time, the acid value growth trend after mixing different proportions of new oil with used fire-resistant oils with different acid values ​​is examined to determine the quality changes of fire-resistant oil during operation.

[0044] Step S02: preparing a mixed oil sample.

[0045] According to the acid value of the fire-resistant oil sample after use by the main steam isolation valve, the unused fire-resistant oil, i.e., new oil, is mixed with the used fire-resistant oil sample in a preset proportion to obtain a plurality of mixed oil samples containing different proportions of new oil.

[0046] In some embodiments, the used fire-resistant oil sample and the unused fire-resistant oil can be phosphate ester fire-resistant oil of the same material, and can be phosphate ester fire-resistant oil of the same brand, for example, AKZO Fyrquel EHC.

[0047] In some embodiments, the step of adding different proportions of unused fire-resistant oil to the used fire-resistant oil sample comprises: (1) if the acid value of the used fire-resistant oil sample is less than 1.5 mgKOH / g, adding different proportions of unused fire-resistant oil to the used fire-resistant oil sample according to a ratio of 0 to 15% of the total volume of the unused fire-resistant oil; (2) if the acid value of the used fire-resistant oil sample is greater than or equal to 1.5 mgKOH / g, adding different proportions of unused fire-resistant oil to the used fire-resistant oil sample according to a ratio of 25 to 100% of the total volume of the unused fire-resistant oil.

[0048] That is, based on the total volume of the used fire-resistant oil sample and the unused fire-resistant oil being 100%, if the acid value of the used fire-resistant oil sample is less than 1.5 mgKOH / g, the mixing ratio of the unused fire-resistant oil is 0-15%, and if the acid value of the used fire-resistant oil sample is greater than or equal to 1.5 mgKOH / g, the mixing ratio of the unused fire-resistant oil is 25-100%. Among them, each used fire-resistant oil sample with different acid values ​​can be added with different proportions of unused fire-resistant oil within the above range to obtain multiple mixed oil samples; of course, the more the number of mixed oil samples configured, the better, and specifically 3-5 mixed oil samples can be configured according to actual needs. The main purpose is to verify through experiments that after different proportions of new and old oil are mixed, the acid value of the mixed oil sample increases quickly after aging, so as to verify the speed of oil aging.

[0049] Specifically, if the acid value of the used fire-resistant oil sample is less than 1.5 mgKOH / g, then it is added to the used fire-resistant oil sample in a ratio of 0%, 5%, 10%, and 15% of the total volume of the unused fire-resistant oil respectively; if the acid value of the used fire-resistant oil sample is greater than or equal to 1.5 mgKOH / g, then it is added to the used fire-resistant oil sample in a ratio of 25%, 50%, 75%, and 100% of the total volume of the unused fire-resistant oil respectively.

[0050] Step S03: Aging process.

[0051] The acid value will generally increase during the aging process. The aging stop criteria are: at least 30 days of aging, and the acid value of each mixed oil sample exceeds 9mgKOH / g. If after 30 days, the acid value of some mixed oil samples is not 9mgKOH / g, continue aging until the acid value of all samples exceeds 9mgKOH / g.

[0052] In some embodiments, the temperature of the aging treatment is 118-122° C. The aging treatment can be performed in a laboratory oven, which is convenient for setting the temperature conditions required for aging.

[0053] In some embodiments, the aging treatment is performed under the conditions of a composite catalyst containing copper and iron, wherein the volume ratio of the mixed oil sample to the weight of copper is 100 mL: 0.4-0.6 g; and the volume ratio of the mixed oil sample to the weight of iron is 100 mL: 2.4-2.6 g.

[0054] In some embodiments, aging the mixed oil sample and monitoring the acid value of the mixed oil sample includes: during the aging process, (1) if the acid value of the mixed oil sample is ≤0.2 mgKOH / g, the acid value of the mixed oil sample is measured every 4 to 5 days; (2) if 0.2 mgKOH / g<the acid value of the mixed oil sample is ≤0.5 mgKOH / g, the acid value of the mixed oil sample is measured every 1 to 2 days; (3) if 0.5 mgKOH / g<the acid value of the mixed oil sample is ≤1.5 mgKOH / g, the acid value of the mixed oil sample is measured every day; (4) if 1.5 mgKOH / g<the acid value of the mixed oil sample is ≤9 mgKOH / g, the acid value of the mixed oil sample is measured every 4 to 5 days; (5) if the acid value of the mixed oil sample is >9 mgKOH / g, the acid value of the mixed oil sample is measured every 6 to 7 days. According to the acid value of each sample, the detection is performed according to the above analysis frequency.

[0055] Generally, if the acid value of the mixed oil sample is ≤0.2mgKOH / g, the acid value will exceed 0.2mgKOH / g after about 9 to 10 days; if the acid value of the mixed oil sample is 0.2mgKOH / g<≤0.5mgKOH / g, the acid value will exceed 0.5mgKOH / g after about 2 to 3 days; if the acid value of the mixed oil sample is 0.5mgKOH / g<≤1.5mgKOH / g, the acid value will exceed 1.5mgKOH / g after about 5 to 6 days; if the acid value of the mixed oil sample is 1.5mgKOH / g<≤9mgKOH / g, the acid value will exceed 9mgKOH / g after about 18 to 20 days. Finally, the acid value of all samples can be tested once on the 30th day after aging to determine the conditions for stopping the acid value measurement: the sample is aged for 30 days and the acid value of all oil samples exceeds 9mgKOH / g.

[0056] Step S04: Quality assessment.

[0057] In some embodiments, evaluating the quality of the fire-resistant oil sample after use includes: (1) if the acid value of the fire-resistant oil sample after use is lower than 1.5 mgKOH / g, the fire-resistant oil sample after use continues to be used; (2) if the acid value of the fire-resistant oil sample after use is equal to or greater than 1.5 mgKOH / g, adding unused fire-resistant oil accounting for at least 15% of the total volume to the fire-resistant oil sample after use continues to be used, or the fire-resistant oil sample after use stops using. For example, if the acid value of the fire-resistant oil sample after use is in the range of 1.5 to 8 mgKOH / g, unused fire-resistant oil accounting for 15 to 90% of the total volume can be added to the fire-resistant oil sample after use continues to be used, and if the acid value of the fire-resistant oil sample after use exceeds 8 mgKOH / g, the fire-resistant oil sample after use stops using.

[0058] Through quality assessment and analysis, when the acid value of the used fire-resistant oil sample is lower than 1.5 mgKOH / g, the growth trend of its acid value after aging is basically consistent with the growth trend of the mixed oil sample mixed with unused fire-resistant oil. Therefore, the used fire-resistant oil sample with such acid value can continue to be used and generally will not deteriorate sharply immediately. When the acid value of the used fire-resistant oil sample is 1.5-8 mgKOH / g, the growth trend of the acid value of the mixed oil sample of unused fire-resistant oil with different proportions is investigated to determine the change of oil quality after the unused fire-resistant oil is replenished during operation (accounting for 15% to 90% of the total volume ratio), providing data support for the daily replenishment of low fire-resistant oil level. When the acid value of the used fire-resistant oil sample is greater than 8 mgKOH / g, the growth trend of the acid value of the mixed oil sample of unused fire-resistant oil with different proportions is investigated to provide data support for oil change in extreme cases. For example, if the acid value reaches 8 mgKOH / g or above, it can be considered to stop using the used fire-resistant oil sample and use 100% new oil.

[0059] In some embodiments, the quality assessment method further comprises detecting the kinematic viscosity and particle contamination of the fire-resistant oil sample after use.

[0060] In order to formulate a more reasonable and feasible oil control standard, starting from the characteristics of VVP main steam isolation valve equipment and fire-resistant oil characteristics, combined with many years of field practice experience of nuclear power bases, the relevant conditions of VVP main steam isolation valve oil deterioration were summarized, and oil performance verification tests were carried out in the laboratory. The main reasons for the reduction of oil performance of the main steam isolation valve fire-resistant oil are: the operating oil temperature is too high, resulting in oil aging, and the oil system has local high temperature; the oil has a large water content, and the oil is hydrolyzed, resulting in a high acid value of the oil. In addition to the acid value, the main indicators of poor oil quality are also important, such as kinematic viscosity and particle contamination. Therefore, the abnormal indicators of the main steam isolation valve fire-resistant oil can be further concentrated on the acid value, kinematic viscosity and particle contamination of the oil.

[0061] Among them, through the quality assessment method of the embodiment of the present application, combined with the field practice experience of nuclear power bases for many years, the following indicators are specified for the main steam isolation valve fire-resistant oil: (1) Acid value: ≤1.5mgKOH / g; the test method can refer to the national standard GB / T264 "Determination of acid value of petroleum products". (2) Kinematic viscosity (40℃): 28.8~35.2mm 2 / s(IOS VG32) / 41.4~50.6mm 2 / s (IOS VG46); the test method can refer to the national standard GB / T265 "Determination of Englert Viscosity of Petroleum Products". (3) Particle contamination (AS4059F): ≤8 / 8; the test method can refer to the power industry standard DL / T432-2007 "Measurement Method of Particle Contamination in Power Oil".

[0062] The applicant has selected acid value through feedback from many years of practical experience in the fire-resistant oil products of main steam isolation valves, combined with the system manual and maintenance outline, and the conclusion of laboratory oil mixing experiments. In addition, kinematic viscosity and particle contamination are further used. These three indicators are used as the main steam isolation valve operating oil control quality monitoring items, and the VVP main steam isolation valve operating oil control quality and oil change diagnosis standards are formulated. The quality assessment method of the fire-resistant oil of the main steam isolation valve of the nuclear power plant in the embodiment of the present application is evaluated.

[0063] After the implementation of the nuclear power plant main steam isolation valve standard, the problem of oil products often exceeding the standard when the nuclear power plants refer to the operating oil quality standard control in the operation and maintenance guidelines for phosphate ester fire-resistant oil for power plants can be reduced. It is in line with the on-site practice and saves manpower and oil costs while ensuring the safety of the equipment. Combined with the quality assessment method of the embodiment of the present application, the fault warning capability of nuclear safety equipment can be greatly improved, providing a solid foundation for ensuring the safety and reliability of the equipment.

[0064] After field practice, the quality assessment method of the embodiment of the present application can timely detect equipment abnormalities and take intervention measures in advance, effectively improving the safety of nuclear power plant units. Therefore, the oil monitoring and quality assessment of the main steam isolation valve anti-oil can be used as a diagnostic standard for oil change of the main steam isolation valve of a nuclear power plant, and has wide promotion and application value in the nuclear power industry.

[0065] The following describes the invention in conjunction with specific embodiments.

[0066] Example 1

[0067] A quality assessment method for fire-resistant oil of main steam isolation valve of nuclear power plant, the specific steps are as follows:

[0068] Step 1: After one fuel cycle of a pressurized water reactor nuclear power plant unit, used fire-resistant oil samples with different acid values ​​are obtained from multiple main steam isolation valves;

[0069] Step 2: According to the acid value of the fire-resistant oil sample after use of the main steam isolation valve, the unused fire-resistant oil (i.e., new oil) is mixed with the used fire-resistant oil sample in a preset ratio to obtain multiple mixed oil samples; wherein the preset ratio is as follows: if the acid value of the used fire-resistant oil sample is less than 1.5 mgKOH / g, the total volume proportions of the unused fire-resistant oil mixed are 0%, 5%, 10%, and 15% respectively; if the acid value of the used fire-resistant oil sample is ≥1.5 mgKOH / g, the total volume proportions of the unused fire-resistant oil mixed are 90%, 75%, 50%, and 25% respectively. The used fire-resistant oil sample and the unused fire-resistant oil are from the same brand (AKZOFyrquel EHC).

[0070] Step 3: subjecting the above-mentioned multiple mixed oil samples to aging treatment (120° C. high temperature, adding copper and iron catalysts for aging, wherein 1 g of copper and 5 g of iron are added to every 200 mL of mixed oil sample), and measuring the initial acid value of each mixed oil sample according to the method of national standard GB / T264, and monitoring the acid value according to the following analysis frequency during the aging process according to the acid value of each mixed oil sample;

[0071] 1) Acid value ≤ 0.2 mgKOH / g, the acid value is measured every 5 days;

[0072] 2) 0.2mgKOH / g<acid value≤0.5mgKOH / g, measure the acid value every 2 days;

[0073] 3) 0.5mgKOH / g<acid value≤1.5mgKOH / g, measure the acid value every day;

[0074] 4) 1.5mgKOH / g<acid value≤9mgKOH / g, measure the acid value every 5 days;

[0075] 5) Acid value>9mgKOH / g, measure the acid value every 7 days;

[0076] On the 30th day after aging, the acid value of all samples was tested once, and the conditions for stopping aging were determined: the samples were aged for at least 30 days and the acid value of all oil samples exceeded 9 mgKOH / g.

[0077] Step 4: Analyze each sample and record the acid value of each sample to obtain a trend chart of the acid value of each sample with aging time; Based on the above acid value trend chart and test results, it can be determined that:

[0078] a) Determine the increase pattern of the acid value of the fire-resistant oil after the main steam isolation valve is used for one fuel cycle. When the acid value of the fire-resistant oil after use is lower than 1.5 mgKOH / g, the growth trend of its acid value after aging is basically consistent with the growth trend of the mixed oil sample after mixing with some new oil. The oil can continue to be used to ensure that it will not deteriorate sharply in the next fuel cycle.

[0079] b) Investigate the acid value growth trend of different proportions of unused new oil mixed with used fire-resistant oil with an acid value of 1.5-8 mgKOH / g, so as to determine the changes in oil quality after the fire-resistant oil is replenished during operation, such as replenishing 15% to 90% of the total volume with new oil, to provide data support for daily replenishment of low fire-resistant oil levels.

[0080] c) Investigate the acid value growth trend after mixing different proportions of unused new oil with used fire-resistant oil with an acid value exceeding 8 mgKOH / g. For example, if the acid value reaches above 8 mgKOH / g, consider stopping the use of the used fire-resistant oil sample to provide data support for oil change in extreme cases.

[0081] See also Figure 1-Figure 4 , is a graph showing the trend of the acid value of the mixed oil sample after four used fire-resistant oil samples with different acid values ​​were mixed with unused fire-resistant oil obtained by the above quality assessment method with aging time. Among them: the first used fire-resistant oil sample is recorded as L2VVP001VV (acid value is 1.19mgKOH / g), the second used fire-resistant oil sample is recorded as L2VVP002VV (acid value is 0.32mgKOH / g), the third used fire-resistant oil sample is recorded as L2VVP003VV (acid value is 8.01mgKOH / g), and the fourth used fire-resistant oil sample is recorded as D2VVP002VV (acid value is 6.89mgKOH / g). The horizontal axis is the aging time (unit: day, specifically 10 days, 20 days, 30 days, 40 days, 50 days, etc., and so on), and the vertical axis is the acid value (unit: mgKOH / g, specifically 1mgKOH / g, 2mgKOH / g, 3mgKOH / g, 4mgKOH / g, 5mgKOH / g, 6mgKOH / g, etc., and so on). "0% mixed oil" means that the new oil added is 0, "5% mixed oil" means that the new oil added accounts for 5% of the total volume, "10% mixed oil" means that the new oil added accounts for 10% of the total volume, "15% mixed oil" means that the new oil added accounts for 15% of the total volume, "25% mixed oil" means that the new oil added accounts for 25% of the total volume, "50% mixed oil" means that the new oil added accounts for 50% of the total volume, "75% mixed oil" means that the new oil added accounts for 75% of the total volume, "90% mixed oil" means that the new oil added accounts for 90% of the total volume, and "100% mixed oil" means that the fire-resistant oil sample is completely replaced with new oil after use. It can be seen from this that the growth trend of the acid value of the first and second used fire-resistant oil samples after aging is basically consistent with the growth trend of the mixed oil sample after mixing with some new oil, and they can be considered to continue to be used. The fourth used fire-resistant oil sample can be considered to continue to be used after adding 75% or even 90% of the total volume of new oil. The third used fire-resistant oil sample can be considered to be discontinued.

[0082] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A quality assessment method for fire-resistant oil of main steam isolation valve of nuclear power plant, characterized in that: include: Take used fire-resistant oil samples with different acid values ​​from multiple main steam isolation valves; adding unused fire-resistant oil in different proportions to the used fire-resistant oil sample to obtain a plurality of mixed oil samples; Performing an aging treatment on the mixed oil sample and monitoring the acid value of the mixed oil sample until the aging is at least 30 days and the acid value of each of the mixed oil samples exceeds 9 mgKOH / g after aging, then stopping the aging; According to the increasing trend of the acid value of the mixed oil sample with aging time, the quality of the used fire-resistant oil sample is evaluated.

2. The quality assessment method according to claim 1, characterized in that: The steps of adding different proportions of unused fire-resistant oil to the used fire-resistant oil sample include: If the acid value of the used fire-resistant oil sample is less than 1.5 mgKOH / g, adding different proportions of the unused fire-resistant oil to the used fire-resistant oil sample according to the ratio of the unused fire-resistant oil to the total volume of 0 to 15%; If the acid value of the used fire-resistant oil sample is greater than or equal to 1.5 mgKOH / g, different proportions of the unused fire-resistant oil are added to the used fire-resistant oil sample according to a ratio of 25-100% of the total volume of the unused fire-resistant oil.

3. The quality assessment method according to claim 2, characterized in that: If the acid value of the used fire-resistant oil sample is less than 1.5 mgKOH / g, then the unused fire-resistant oil is added to the used fire-resistant oil sample in a ratio of 0%, 5%, 10%, and 15% of the total volume; If the acid value of the used fire-resistant oil sample is greater than or equal to 1.5 mgKOH / g, the unused fire-resistant oil is added to the used fire-resistant oil sample in a ratio of 25%, 50%, 75% and 100% of the total volume.

4. The quality assessment method according to claim 1, characterized in that: The temperature of the aging treatment is 118-122°C.

5. The quality assessment method according to claim 1, characterized in that: The aging treatment is carried out under the condition of a composite catalyst containing copper and iron.

6. The quality assessment method according to claim 5, characterized in that: The volume ratio of the mixed oil sample to the weight of the copper is 100 mL: 0.4-0.6 g; and / or the volume ratio of the mixed oil sample to the weight of the iron is 100 mL: 2.4-2.6 g.

7. The quality assessment method according to claim 1, characterized in that: The method of subjecting the mixed oil sample to aging treatment and monitoring the acid value of the mixed oil sample comprises: During the aging treatment, if the acid value of the mixed oil sample is ≤0.2 mgKOH / g, the acid value of the mixed oil sample is measured every 4 to 5 days; if 0.2 mgKOH / g<the acid value of the mixed oil sample is ≤0.5 mgKOH / g, the acid value of the mixed oil sample is measured every 1 to 2 days; if 0.5 mgKOH / g<the acid value of the mixed oil sample is ≤1.5 mgKOH / g, the acid value of the mixed oil sample is measured every day; if 1.5 mgKOH / g<the acid value of the mixed oil sample is ≤9 mgKOH / g, the acid value of the mixed oil sample is measured every 4 to 5 days; if the acid value of the mixed oil sample is >9 mgKOH / g, the acid value of the mixed oil sample is measured every 6 to 7 days.

8. The quality assessment method according to any one of claims 1 to 7, characterized in that: The quality assessment of the fire-resistant oil sample after use includes: If the acid value of the used fire-resistant oil sample is lower than 1.5 mgKOH / g, the used fire-resistant oil sample continues to be used; If the acid value of the used fire-resistant oil sample is equal to or greater than 1.5 mgKOH / g, at least 15% of the unused fire-resistant oil is added to the used fire-resistant oil sample and the used fire-resistant oil sample is continued to be used, or the used fire-resistant oil sample is stopped.

9. The quality assessment method according to any one of claims 1 to 7, characterized in that: Also includes: The kinematic viscosity and particle contamination of the used fire-resistant oil sample were tested.

10. The quality assessment method according to any one of claims 1 to 7, characterized in that: The used fire-resistant oil sample and the unused fire-resistant oil are made of the same material, namely, phosphate fire-resistant oil.

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