A method for assessing the lifespan of cooling water expansion joints in nuclear power emergency diesel engines

Abstract

This invention belongs to the field of nuclear power plant equipment management, specifically relating to a method for assessing the lifespan of cooling water expansion joints for nuclear power emergency diesel engines. The method includes: Step 1, determining the operating conditions of the inner rubber layer of the expansion joint; based on the data information of the diesel engine cooling water expansion joint, determining the operating conditions of the inner rubber layer; Step 2, conducting high-temperature accelerated aging tests on the inner rubber layer material and establishing an aging model; based on the operating condition information of the inner rubber layer in Step 1, conducting high-temperature accelerated aging tests on the inner rubber layer and establishing an aging model of aging performance indicators and aging time at operating temperature; Step 3, conducting product evaluation tests to obtain the critical values ​​of the aging performance indicators of the cooling water expansion joint; Step 4, substituting the critical values ​​of the aging performance indicators into the aging model to calculate the total lifespan of the expansion joint. This method, through practice, can guide the lifespan assessment of cooling water expansion joints for nuclear power emergency diesel engines, providing technical guidance for the lifespan management of nuclear power emergency diesel engines.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plant emergency diesel engine management, specifically relating to a method for assessing the lifespan of the cooling water expansion joint of a nuclear power emergency diesel engine. Background Technology

[0002] Emergency diesel engines serve as the last line of defense in nuclear power plants and are crucial nuclear safety facilities. The aging lifespan of the cooling water expansion joints in these engines is closely related to factors such as the operating medium, temperature, and engine vibration. In recent years, several nuclear power plants in China have experienced aging failures of their emergency diesel engine cooling water expansion joints, rendering them unusable. Currently, there is a lack of a scientific method for evaluating the lifespan of these joints to guide lifespan management in nuclear power plants. Summary of the Invention

[0003] This invention provides a method for assessing the lifespan of the cooling water expansion joint of a nuclear power emergency diesel engine, addressing the problem of the lack of existing methods for evaluating the lifespan of the cooling water expansion joint of a nuclear power emergency diesel engine.

[0004] The technical solution of the present invention is as follows:

[0005] This invention proposes a method for evaluating the service life of cooling water expansion joints in nuclear power emergency diesel engines, the method comprising:

[0006] Step 1: Determine the operating conditions of the inner rubber layer of the expansion joint; Based on the information of the diesel engine cooling water expansion joint, determine the operating conditions of the inner rubber layer of the diesel engine cooling water expansion joint. The operating conditions of the inner rubber layer include the operating medium, operating temperature, cooling water expansion joint installation information, and vibration information.

[0007] Step 2: Conduct a high-temperature accelerated aging test on the inner rubber layer material and establish an aging model; Based on the operating condition information of the inner rubber layer in Step 1, conduct a high-temperature accelerated aging test on the inner rubber layer of the cooling water expansion joint, and establish an aging model of aging performance indicators and aging time at the operating temperature by fitting. Specifically, this includes: obtaining the aging rate constant of the inner rubber layer material of the cooling water expansion joint at the diesel engine operating temperature based on the high-temperature accelerated aging test data, and establishing an aging model of aging performance indicators and aging time at the operating temperature by fitting; The aging performance indicator is the compression set rate; The high-temperature accelerated aging test medium is the same as the antifreeze medium of the emergency diesel engine;

[0008] Step 3: Conduct product evaluation tests to obtain the critical values ​​of the aging performance indicators of the cooling water expansion joint. The product evaluation tests specifically include: high-temperature accelerated aging tests, dynamic fatigue tests, and pressure tests on the cooling water expansion joint to ultimately obtain the critical values ​​of the aging performance indicators. After the high-temperature accelerated aging test, the appearance of the cooling water expansion joint is checked for any abnormalities. Then, dynamic fatigue tests and pressure tests are conducted on the cooling water expansion joint. The pressure test pressure is output by the pressure test device. If the cooling water expansion joint shows no abnormalities, the above tests are repeated until the cooling water expansion joint reaches a critical state. The critical values ​​of the aging performance indicators of the cooling water expansion joint are determined based on the test results. The vibration input value for the product dynamic fatigue test is the actual vibration value of the cooling water expansion joint, and the pressure value for the pressure test must not be less than the actual operating pressure value of the cooling water expansion joint.

[0009] In some embodiments, the aging model established by fitting the aging performance index and aging time at the operating temperature in step two is specifically fitted in the form of formula (1), where: y is the compression permanent deformation rate of the diesel engine cooling water expansion joint, B is the experimental constant, K is the aging rate constant, t is the aging time, and α is the undetermined constant for fitting.

[0010] y = B × exp(-K × t α (1)

[0011] In some embodiments, in step four, the remaining lifespan of the cooling water expansion joint is calculated by subtracting the actual operating time of the cooling water expansion joint from its total lifespan.

[0012] In some embodiments, in step three, the high-temperature accelerated aging test medium should be the same as the diesel engine antifreeze.

[0013] In some embodiments, the pressure testing device in step three includes a gas tank, a regulating valve, a shut-off valve, a flange joint, an upper flange, a lower flange, a cooling water expansion joint, and a water storage container. The gas tank is connected in series with the regulating valve, the shut-off valve, and one end of the flange joint through a pipeline. The other end of the flange joint is connected to the upper flange. The lower end of the upper flange is connected to the cooling water expansion joint, and the lower end of the cooling water expansion joint is connected to the lower flange. The upper flange and the lower flange are used to seal the cooling water expansion joint. A water storage container is located outside the cooling water expansion joint.

[0014] In some embodiments, the pressure testing apparatus has a gas tank filled with inert gas, and the gas tank pressure is greater than the design pressure of the cooling water expansion joint.

[0015] In some embodiments, a first pressure gauge is provided between the gas tank and the regulating valve, and a second pressure gauge is provided between the regulating valve and the shut-off valve. The first pressure gauge is used to monitor the pressure value before the regulating valve, and the second pressure gauge is used to monitor the pressure value after the regulating valve. The regulating valve and the shut-off valve are used to control the pressure of the pressurized gas.

[0016] In some embodiments, the pressure test conducted using a pressure testing device includes the following steps: First, water is injected into the water storage container to ensure that the liquid level is higher than the flange joint, and the pressure of the gas tank is confirmed by observing the first pressure gauge; then, the regulating valve and the shut-off valve are opened, and the pressure of the first pressure gauge and the second pressure gauge are observed to see if they meet the test pressure requirements, and the flange joint is checked for any abnormal leakage; the pressure is maintained for at least 5 minutes, and the presence of air bubbles in the water of the water storage container is observed and recorded. If no air bubbles are produced, the cooling water expansion joint is normal.

[0017] The implementation of this invention has the following beneficial effects:

[0018] This invention establishes a scientific and reasonable method for assessing the service life of cooling water in nuclear power emergency diesel engines. Through practice, it has been shown to guide the assessment of the service life of cooling water in nuclear power emergency diesel engines, thereby providing technical guidance for the service life management of cooling water in nuclear power emergency diesel engines. Attached Figure Description

[0019] Figure 1 A flowchart of a method for assessing the lifespan of a cooling water expansion joint in a nuclear power emergency diesel engine, provided as an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of a pressure test apparatus for a method to assess the lifespan of a cooling water expansion joint in a nuclear power emergency diesel engine, provided in an embodiment of the present invention;

[0021] Reference numerals in the attached diagram: 1. Gas tank; 2. First pressure gauge; 3. Regulating valve; 4. Second pressure gauge; 5. Shut-off valve; 6. Pipeline; 7. Flange joint; 8. Upper flange; 9. Cooling water expansion joint; 10. Lower flange; 11. Water storage container. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0023] This invention provides, with at least one embodiment, a method for assessing the lifespan of cooling water expansion joints in nuclear power emergency diesel engines. The method includes the following steps:

[0024] This invention proposes a method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine, the method comprising:

[0025] Step 1: Determine the operating conditions of the inner rubber layer of the expansion joint; Based on the information of the diesel engine cooling water expansion joint 9, determine the operating conditions of the inner rubber layer of the diesel engine cooling water expansion joint 9. The operating conditions of the inner rubber layer include the operating medium, operating temperature, installation information of the cooling water expansion joint 9, and vibration information.

[0026] 2. Step Two: Conduct high-temperature accelerated aging tests on the inner rubber layer material and establish an aging model; Based on the operating condition information of the inner rubber layer in Step One, establish an aging model of aging performance index and aging time at operating temperature by fitting; Specifically, this includes: selecting compression set as the aging performance index, obtaining the aging rate constant of the inner rubber layer material of the cooling water expansion joint at the diesel engine operating temperature based on the high-temperature accelerated aging test data, and establishing an aging model of aging performance index and aging time at operating temperature by fitting. The aging model is specifically fitted using the form of formula (1), where: y is the compression set rate of the diesel engine cooling water expansion joint 9, B is the test constant, K is the aging rate constant, t is the aging time, and α is the undetermined constant for fitting.

[0027] y = B × exp(-K × t α (1)

[0028] Step 3: Conduct product evaluation tests to obtain the critical values ​​of the aging performance indicators of the cooling water expansion joint 9. This includes: conducting high-temperature accelerated aging tests, dynamic fatigue tests, and pressure tests on the cooling water expansion joint 9 to ultimately obtain the critical values ​​of the aging performance indicators. After the high-temperature accelerated aging test, inspect the appearance of the cooling water expansion joint 9 for any abnormalities. Then, conduct dynamic fatigue tests and pressure tests on the cooling water expansion joint 9. The pressure test pressure is output by the pressure test device. The dynamic fatigue test simulates vibration conditions based on the actual vibration values ​​on site. After the test, if no cracks or other abnormalities are found in the appearance, the pressure test is used for acceptance. If the cooling water expansion joint 9 shows no abnormalities, repeat the above tests until the cooling water expansion joint 9 reaches the critical state. Based on the test results, determine the critical values ​​of the aging performance indicators of the cooling water expansion joint 9. The vibration input value for the product dynamic fatigue test is the actual vibration value of the cooling water expansion joint 9, and the pressure value for the pressure test must not be less than the actual operating pressure value of the cooling water expansion joint 9.

[0029] Step 4: Substitute the critical values ​​of the aging performance indicators into the aging model to calculate the total lifespan of the cooling water expansion joint 9. Subtract the actual operating time of the cooling water expansion joint 9 from its total lifespan to calculate its remaining lifespan.

[0030] In some embodiments, in steps 2 and 3, the aging performance index is the compression set rate. The high-temperature accelerated aging test medium should be the same as the diesel engine antifreeze.

[0031] This invention establishes a method for scientifically evaluating the service life of cooling water expansion joints in nuclear power emergency diesel engines, in order to assess the service life of cooling water expansion joints in power plant emergency diesel engines and guide the service life management of cooling water expansion joints in nuclear power plants.

[0032] In step three, a pressure testing device is proposed. This invention provides a pressure testing device for the service life of a nuclear power emergency diesel engine cooling water expansion joint, used in the pressure testing of the service life assessment method for nuclear power emergency diesel engine cooling water expansion joints. The device includes a gas tank 1, a regulating valve 3, a shut-off valve 5, a flange joint 7, an upper flange 8, a lower flange 10, a cooling water expansion joint 9, and a water storage container 11. The gas tank 1 is filled with inert gas, and its pressure is greater than the design pressure of the cooling water expansion joint. The gas tank 1 is connected in series with one end of the regulating valve 3, the shut-off valve 5, and the flange joint 7 via a pipeline 6. A first pressure gauge 2 is provided between the gas tank 1 and the regulating valve 3, and a second pressure gauge 4 is provided between the regulating valve 3 and the shut-off valve 5. The first pressure gauge 2 is used to monitor the pressure value before the regulating valve 3, and the second pressure gauge 4 is used to monitor the pressure value after the regulating valve 3. The regulating valve 3 and the shut-off valve 5 are used to control the pressure of the pressurized gas. The other end of the flange joint 7 is connected to the upper flange 8. The lower end of the upper flange 8 is connected to the cooling water expansion joint 9. The lower end of the cooling water expansion joint 9 is connected to the lower flange 10. The upper flange 8 and the lower flange 10 seal the cooling water expansion joint 9. The cooling water expansion joint 9 has a water storage container 11 on its outside.

[0033] This invention also proposes a life-cycle pressure test method for the cooling water expansion joint of a nuclear power emergency diesel engine, used in a nuclear power emergency diesel engine cooling water expansion joint life-cycle pressure test device. The method includes:

[0034] Step 1: Fill the water storage container 11 with water to ensure that the liquid level is higher than the highest point of the flange joint 7;

[0035] Step 2: Observe the first pressure gauge 2 to confirm that the pressure of gas tank 1 meets the requirements;

[0036] Step 3: Open regulating valve 3 and shut-off valve 4, observe whether the pressure of the first pressure gauge 2 and the second pressure gauge 4 meets the test pressure requirements, and check that there is no abnormal leakage at flange joint 7.

[0037] Step 4: Maintain pressure for at least 5 minutes and observe whether there are bubbles in the water in the water storage container 11. If no bubbles are produced, observe and record whether bubbles are produced in the water in the water storage container. If no bubbles are produced, the cooling water expansion joint is normal.

[0038] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for evaluating the service life of cooling water expansion joints in nuclear power emergency diesel engines, characterized in that, The method includes: Step 1: Determine the operating conditions of the inner rubber layer of the expansion joint; Based on the information of the diesel engine cooling water expansion joint, determine the operating conditions of the inner rubber layer of the diesel engine cooling water expansion joint. The operating conditions of the inner rubber layer include the operating medium, operating temperature, cooling water expansion joint installation information, and vibration information. Step 2: Conduct a high-temperature accelerated aging test on the inner rubber layer material and establish an aging model; Based on the operating condition information of the inner rubber layer in Step 1, conduct a high-temperature accelerated aging test on the inner rubber layer of the cooling water expansion joint, and establish an aging model of aging performance indicators and aging time at the operating temperature by fitting. Specifically, this includes: obtaining the aging rate constant of the inner rubber layer material of the cooling water expansion joint at the diesel engine operating temperature based on the high-temperature accelerated aging test data, and establishing an aging model of aging performance indicators and aging time at the operating temperature by fitting; The aging performance indicator is the compression set rate; The high-temperature accelerated aging test medium is the same as the antifreeze medium of the emergency diesel engine; Step 3: Conduct product evaluation tests to obtain the critical values ​​of the aging performance indicators of the cooling water expansion joint. The product evaluation tests specifically include: high-temperature accelerated aging tests, dynamic fatigue tests, and pressure tests on the cooling water expansion joint to ultimately obtain the critical values ​​of the aging performance indicators. After the high-temperature accelerated aging test, the appearance of the cooling water expansion joint is checked for any abnormalities. Then, dynamic fatigue tests and pressure tests are conducted on the cooling water expansion joint. The pressure test pressure is output by the pressure test device. If the cooling water expansion joint shows no abnormalities, the above tests are repeated until the cooling water expansion joint reaches a critical state. The critical values ​​of the aging performance indicators of the cooling water expansion joint are determined based on the test results. The vibration input value for the product dynamic fatigue test is the actual vibration value of the cooling water expansion joint, and the pressure value for the pressure test must not be less than the actual operating pressure value of the cooling water expansion joint. Step 4: Substitute the critical values ​​of the aging performance indicators into the aging model to calculate the total lifespan of the expansion joint.

2. The method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine according to claim 1, characterized in that, In step two, the aging model of aging performance index and aging time under operating temperature is established by fitting, specifically by using formula (1), where: y is the permanent compression deformation rate of the diesel engine cooling water expansion joint, B is the experimental constant, K is the aging rate constant, t is the aging time, and α is the undetermined constant of the fitting. y=B×exp(-K×t α ) (1)。 3. The method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine according to claim 1, characterized in that, In step four, the remaining lifespan of the cooling water expansion joint is calculated by subtracting its actual operating time from its total lifespan.

4. The method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine according to claim 1, characterized in that, In step three, the high-temperature accelerated aging test medium should be the same as the diesel engine antifreeze.

5. The method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine according to claim 1, characterized in that, The pressure testing device in step three includes a gas tank, a regulating valve, a shut-off valve, a flange joint, an upper flange, a lower flange, a cooling water expansion joint, and a water storage container. The gas tank is connected in series with the regulating valve, the shut-off valve, and one end of the flange joint via a pipeline. The other end of the flange joint is connected to the upper flange. The lower end of the upper flange is connected to the cooling water expansion joint, and the lower end of the cooling water expansion joint is connected to the lower flange. The upper flange and the lower flange are used to seal the cooling water expansion joint. A water storage container is located outside the cooling water expansion joint.

6. The method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine according to claim 5, characterized in that, The pressure testing device has an inert gas tank, and the pressure of the tank is greater than the design pressure of the cooling water expansion joint.

7. The method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine according to claim 6, characterized in that, A first pressure gauge is provided between the gas tank and the regulating valve, and a second pressure gauge is provided between the regulating valve and the shut-off valve. The first pressure gauge is used to monitor the pressure value before the regulating valve, and the second pressure gauge is used to monitor the pressure value after the regulating valve. The regulating valve and the shut-off valve are used to control the pressure of the pressurized gas.

8. The method for evaluating the service life of the cooling water expansion joint in a nuclear power emergency diesel engine according to claim 5, characterized in that, The pressure test conducted using a pressure testing device includes the following steps: First, water is injected into the storage container to ensure that the liquid level is higher than the flange joint, and the pressure of the gas tank is confirmed by observing the first pressure gauge; then, the regulating valve and the shut-off valve are opened, and the pressure of the first and second pressure gauges is observed to see if they meet the test pressure requirements, and the flange joint is checked for any abnormal leakage; the pressure is maintained for at least 5 minutes, and the presence of air bubbles in the water of the storage container is observed and recorded. If no air bubbles are produced, the cooling water expansion joint is normal.

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