Testing device and method for verifying performance of mechanical plug of heat transfer tube of heat exchanger

Abstract

The invention provides a test device and method for verifying the performance of a mechanical plug of a heat transfer tube of a heat exchanger. The method comprises the following steps: S1, performing a hydrostatic pressure test, a cycle test and a thermal shock test on a plug test piece; carrying out a corrosion test on the plug test piece; carrying out an ultra-hydrostatic test on the plug test piece, and recording a failure value; s2, after the hydrostatic pressure test, the cycle test and the thermal shock test are completed, whether the plug test piece meets the acceptance criterion of the warm-pressure test is judged; after the corrosion test is finished, judging whether the plug test piece meets a corrosion test acceptance criterion or not; if the temperature and pressure test acceptance criterion and the corrosion test acceptance criterion are met at the same time, the performance of the plug test piece is evaluated to be qualified, and if any one of the temperature and pressure test acceptance criterion and the corrosion test acceptance criterion is not met, the performance of the plug test piece is evaluated to be unqualified. Performance verification of the heat transfer tube mechanical plug of the steam generator of the nuclear power plant can be quickly realized.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger heat transfer tube performance testing technology, specifically to a test apparatus and method for verifying the performance of mechanical plugs for heat exchanger heat transfer tubes. Background Technology

[0002] As a key piece of equipment in a nuclear power system, the steam generator plays a crucial role in converting the heat energy generated by the nuclear reactor into steam energy, and serves as a critical interface connecting the primary and secondary loops. The heat transfer tubes of the steam generator are a critical component of the primary loop pressure boundary, accounting for 80% of the total area of ​​the primary coolant system pressure boundary. These heat transfer tubes are an important barrier against the leakage of radioactive fission products, but they are also the weakest link in the primary loop system. During service, they are subject to mechanical or chemical damage from fretting wear, coolant erosion, and high-temperature and high-pressure operating environments, posing a risk of rupture. To prevent radioactive materials from leaking from damaged heat transfer tubes into the secondary loop, plugging is necessary. Currently, mechanical plugging is one of the most commonly used heat transfer tube repair techniques. Mechanical force is used to ensure a tight seal between the outer wall of the plug and the inner wall of the heat transfer tube and the tube sheet orifices, thus sealing the heat transfer tube. Compared with other plugging technologies such as welding, mechanical plugging has the advantages of being simple, technologically mature, and highly operable. The plug is easy to remove, and once the technology matures, the plugged tube can be lined or the damaged heat transfer tube can be reused under the premise of ensuring safety. Therefore, it is widely used in the maintenance of heat transfer tubes of steam generators in nuclear power plants.

[0003] After the plug is installed on the heat transfer tubes of the steam generator, it will bear the loads of the primary and secondary loops of the steam generator. The performance of the plug directly affects the safety and reliability of the plugging process. To ensure the reliability and safety of the mechanical plug sealing process, a comprehensive process evaluation of the plug is required, involving rigorous analysis and experimental verification. Process evaluation verifies whether the mechanical plug can stably seal the heat transfer tubes under specified operating conditions over a long period, preventing the leakage of radioactive materials. Simultaneously, process evaluation is a necessary measure to meet the requirements of nuclear safety regulations and relevant standards, contributing to the safe operation of the nuclear power plant and providing technical support for its operation and maintenance.

[0004] Currently, the process qualification of plugs is mainly based on the requirements for plugs and process qualification in Chapter 4713, "Pluging Heat Exchanger Heat Transfer Tubes with Expansion Tubes," of ASME XIIWA, "Inspection and Monitoring Rules for Light Water-Cooled Nuclear Power Plant Components," and the qualification requirements in RSE-MⅡ 3.2.3 / 3.2.4. However, the standards only specify general test requirements, which cannot support the full-process evaluation of plugs. The cyclic testing requirements for plugs and process qualification only specify that the specimens should undergo pressure testing and thermal cycling testing to simulate the effects of heat exchanger heating and cooling during the expected lifespan of the plug. However, both pressure testing and thermal cycling testing include various tests, such as single-factor cycling tests and multi-factor cross-cycle tests, for which the standards do not provide clear and feasible solutions. This has resulted in numerous experiments conducted by domestic enterprises and universities for the process evaluation of plugs, but a set of scientific and meticulous analysis methods and experimental systems that can be used for engineering implementation have not been formed. There are many deficiencies in the comprehensiveness and reliability of analysis and experimental methodologies, which greatly restricts the localization of mechanical plugs for heat transfer tubes.

[0005] With the rapid and high-quality development of nuclear power systems, the demand for developing high-quality heat transfer tube plugs for steam generators is constantly increasing, and higher requirements are being placed on the scientific rigor and comprehensiveness of plug process evaluation tests. How to establish a scientific and reliable test system and methods, and a standardized test process for mechanical plugs for heat transfer tubes is an urgent problem to be solved.

[0006] In view of this, the inventors of this application have designed an experimental device and method for verifying the performance of mechanical plugs for heat exchanger heat transfer tubes, in order to overcome the above-mentioned technical problems. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies in the existing technology of lacking a scientific and reliable test system and method and a standardized test procedure for mechanical plugs for heat transfer tubes, and to provide a test device and method for verifying the performance of mechanical plugs for heat transfer tubes of heat exchangers.

[0008] The present invention solves the above-mentioned technical problems through the following technical solution:

[0009] This invention provides a test method for verifying the performance of mechanical plugs for heat transfer tubes in heat exchangers. The method includes the following steps: S1. Performing hydrostatic pressure tests, cyclic tests, and thermal shock tests on the plug test specimens; conducting corrosion tests on the plug test specimens; conducting overpressure tests on the plug test specimens and recording failure values; S2. After the hydrostatic pressure tests, cyclic tests, and thermal shock tests are completed, determining whether the plug test specimens meet the temperature and pressure test acceptance criteria; after the corrosion test is completed, determining whether the plug test specimens meet the corrosion test acceptance criteria; if both the temperature and pressure test acceptance criteria and the corrosion test acceptance criteria are met simultaneously, the plug test specimens are deemed to have qualified performance; if either the temperature and pressure test acceptance criteria or the corrosion test acceptance criteria are not met, the plug test specimens are deemed to have unqualified performance.

[0010] According to one or more embodiments of the present invention, the cyclic test includes a constant temperature and pressure cyclic test, a temperature and pressure dual cyclic test, and a constant pressure and temperature cyclic test; the acceptance criteria for the temperature and pressure test include the requirement for helium leakage after the hydrostatic test.

[0011] According to one or more embodiments of the present invention, the thermo-pressure test acceptance criteria also include a maximum allowable movement distance requirement. If both the helium leakage requirement after water pressure and the maximum allowable movement distance requirement are met, then the thermo-pressure test acceptance criteria are met.

[0012] According to one or more embodiments of the present invention, the test conditions for the hydrostatic test are set as follows: pressure is maintained at 1.5 times the design pressure or 3 times the maximum pressure difference of the tube sheet for 1 hour; the hydrostatic test is performed on the primary side and the secondary side of the plug test piece respectively; the acceptance criteria for the hydrostatic test are set as follows: after the hydrostatic test of the plug test piece is completed on the primary side and the secondary side, a helium leak test is performed respectively, which must meet the helium leak rate requirement of being less than the set value.

[0013] According to one or more embodiments of the present invention, the overpressure test involves slowly pressurizing the secondary side of the plug test piece until the plug test piece completely falls off or the pipe wall bursts, and recording the pressure value of the sealing failure.

[0014] According to one or more embodiments of the present invention, the test conditions for the isothermal pressure cyclic test are set as follows: the primary side test temperature is the primary side design temperature, and the cyclic test pressure range is the sum of the primary side design pressure and the maximum pressure difference between the primary and secondary sides; the secondary side test temperature is the secondary side design temperature, and the cyclic test pressure range is the sum of the saturated water pressure at the secondary side design temperature and the maximum pressure difference between the secondary and primary sides; the number of cycles is the number of transients that can encompass the design transients exceeding the set pressure fluctuation range; for the plug test piece, the principle of primary side first and secondary side second is followed, and isothermal pressure cyclic tests are performed according to the test conditions.

[0015] According to one or more embodiments of the present invention, the test conditions for the temperature and pressure dual-cycle test are set as follows: the medium is boron-lithium water, the water chemical parameters are adjusted to be consistent with the primary side water chemical parameters of the steam generator design conditions, the temperature is heated to the primary side design temperature at a temperature gradient of 58-120℃ / h, the pressure is increased from atmospheric pressure to the primary side design pressure as the temperature rises, the temperature is held at the highest temperature for 3 hours and the highest pressure is maintained, the temperature is cooled to 50℃ at a cooling rate greater than 58℃ / h, the pressure is reduced to atmospheric pressure as the temperature drops, and the pressure is kept higher than the saturated vapor pressure at the corresponding temperature throughout the process, completing one cycle, and the number of cycles is at least 4; the temperature and pressure dual-cycle test is performed on the primary side of the plug test piece according to the test conditions.

[0016] According to one or more embodiments of the present invention, the test conditions for the constant pressure temperature cycling test are set as follows: the primary side medium is boron-lithium water, the secondary side medium is deionized water, the water chemical parameters are adjusted to be consistent with the primary and secondary side water chemical parameters under the design conditions of the steam generator, the primary side test pressure is taken as the primary side design pressure, the temperature cycling range is from room temperature to the primary side design temperature, the number of cycles takes into account the number of power plant heating and cooling cycles, and according to the design transients, the number of combined heating and cooling transients across the entire temperature range of the power plant is included; for the plug test piece, the principle of primary side first and secondary side second is followed, and constant pressure temperature cycling tests are performed separately according to the test conditions.

[0017] According to one or more embodiments of the present invention, the test conditions for the thermal shock test are set as follows: the temperature change range is from room temperature to the primary side design temperature, the temperature rise range is from room temperature to the primary side design temperature, after removal, the test piece is cooled by an air cooling device up to 150°C, cooled by a spray cooling device from 150°C to 80°C, cooled by a spray cooling device from 80°C to room temperature, and the number of cycles is 10; the plug test piece is subjected to thermal shock test according to the test conditions.

[0018] According to one or more embodiments of the present invention, the helium leakage requirement after the hydrostatic test is as follows: the plug test piece is subjected to a hydrostatic test and a helium leak detection test, and the helium leakage rate after the hydrostatic test is less than a set value; the maximum allowable movement distance requirement is as follows: the movement distance of the plug test piece must be less than the maximum allowable movement distance requirement.

[0019] According to one or more embodiments of the present invention, the test conditions for the corrosion test are set as follows: the medium is a degassed NaOH solution with a concentration of 100±3 g / L, the temperature is 350±3℃, the pressure is 152±8 bar (the pressure error depends on the temperature error), and the test time is at least 1000 h; the plug test piece is subjected to corrosion test according to the test conditions; the corrosion test acceptance criteria are set as follows: after the plug test piece completes the corrosion test, a hydrostatic test is performed, and a helium leak test is performed, which must meet the helium leak rate requirement of <10^(-8) Pa·m^3 / s; and the plug test piece is cut along the center line of the end face by wire cutting, and after grinding and polishing, the cross-section of the plug test piece tube is observed, focusing on the stress corrosion morphology on the inner side of the tube cross-section. The cross-sectional view is magnified, and if no obvious corrosion cracks are observed, it passes; otherwise, it fails.

[0020] This invention also provides a test apparatus for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes. The apparatus is characterized in that it is used to perform the test method described above for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes. The test apparatus includes a hydrostatic test device, a constant temperature and pressure cycling test device, a temperature and pressure cycling test device, a thermal shock test device, and a corrosion test device. The hydrostatic test device is used for hydrostatic pressure tests and overpressure tests. The constant temperature and pressure cycling test device is used for constant temperature and pressure cycling tests. The temperature and pressure cycling test device is used for temperature and pressure dual-cycle tests and constant pressure temperature cycling tests. The thermal shock test device is used for thermal shock tests. The corrosion test device is used for corrosion tests.

[0021] According to one or more embodiments of the present invention, the hydrostatic testing equipment includes a high-pressure water supply circuit and a data acquisition and control system; the high-pressure water supply circuit includes a water supply branch and a water return branch, and a plug test piece is connected between the water supply branch and the water return branch; the water supply branch includes a water tank, a low-pressure booster pump, a high-pressure booster pump, and a pressure sensor connected sequentially along the water flow direction; the water return branch includes an electromagnetic pressure relief valve; the high-pressure booster pump is driven by air pressure, and a compressed air source and an electromagnetic valve are provided on its drive pipeline; the data acquisition and control system is electrically or communicatively connected to the electromagnetic valve, the electromagnetic pressure relief valve, and the pressure sensor.

[0022] According to one or more embodiments of the present invention, the constant temperature and pressure cycling test equipment includes a pressure regulating circuit, a high-temperature reactor, a data acquisition and control system, and a pressure monitoring module; the pressure regulating circuit includes a water supply branch and a return water branch, the water supply branch including a water tank, a high-pressure pump, and a solenoid valve connected sequentially along the water flow direction; the return water branch includes a solenoid pressure relief valve; a plug test piece is placed in the high-temperature reactor, one end connected between the water supply branch and the return water branch, and the other end connected to the pressure monitoring module; the high-temperature reactor is equipped with a thermocouple; the data acquisition and control system is electrically or communicatively connected to the thermocouple, the pressure monitoring module, the solenoid valve, and the solenoid pressure relief valve.

[0023] According to one or more embodiments of the present invention, the temperature and pressure cycling test equipment includes a pressure regulating circuit, a water chemistry circuit, a high-temperature and high-pressure reactor, a cooling system, a data acquisition and control system, and a pressure monitoring module; the pressure regulating circuit includes a water supply branch and a return water branch, the water supply branch including a water tank, a high-pressure pump, and a solenoid valve connected sequentially along the water flow direction; the return water branch including a solenoid pressure relief valve; the water chemistry circuit including a high-pressure metering pump, a dosing point, a peristaltic pump, a gas source solenoid valve, and a hydrogen source connected sequentially along the water flow direction; the cooling system includes a heat exchanger connected between the water supply branch and the return water branch; a plug test piece is placed in the high-temperature and high-pressure reactor, one end connected to the heat exchanger and the other end connected to the pressure monitoring module; the high-temperature and high-pressure reactor is equipped with a thermocouple; the data acquisition and control system is electrically or communicatively connected to the thermocouple, the pressure monitoring module, the solenoid valve, the solenoid pressure relief valve, and the gas source solenoid valve.

[0024] According to one or more embodiments of the present invention, the thermal shock testing equipment includes a high-temperature furnace, a cooling system, and a data acquisition and control system; the cooling system includes an air-cooling device, a spray cooling device, and a shower cooling device; a thermocouple is installed inside the high-temperature furnace, and a test thermocouple is connected to the plug test piece; the data acquisition and control system is electrically or communicatively connected to the thermocouple and the test thermocouple.

[0025] According to one or more embodiments of the present invention, the corrosion testing equipment includes a reaction vessel and a data acquisition and control system; the data acquisition and control system is electrically or communicatively connected to the reaction vessel.

[0026] The positive and progressive effects of this invention are as follows:

[0027] The test method and apparatus for verifying the performance of mechanical plugs on heat exchanger tubes of the present invention have at least the following advantages:

[0028] I. This invention supplements and refines the verification test requirements that are not clearly defined in existing specifications and standards, including hydrostatic pressure test, overpressure test, constant temperature and pressure cycle test, constant pressure and temperature cycle test, temperature and pressure dual cycle test, thermal shock test and corrosion test.

[0029] II. This invention establishes a test device and method that can scientifically and comprehensively verify the performance of mechanical plugs for heat transfer tubes, and provides an executable and standardized test procedure and scheme.

[0030] Third, this invention can quickly verify the performance of the plug. By reasonably setting up the heating, cooling and control system of the test circuit, the temperature cycle test cycle can be controlled at an efficient level of 500 times / month.

[0031] Fourth, by adopting a data acquisition and control integrated module, it is possible to achieve rapid simulation of different working conditions and precise control of test parameters. Attached Figure Description

[0032] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features, wherein:

[0033] Figure 1 This is a schematic flowchart of an embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube according to the present invention.

[0034] Figure 2 This is a schematic diagram of the water pressure test equipment in one embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention.

[0035] Figure 3 This is a schematic diagram of the structure of a constant temperature and pressure cycling test device in one embodiment of the test apparatus for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention.

[0036] Figure 4 This is a schematic diagram of the temperature and pressure cycling test equipment in one embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention.

[0037] Figure 5 This is a schematic diagram of the thermal shock test equipment in one embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention.

[0038] Figure 6 This is a schematic diagram of the corrosion test equipment in one embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] Reference will now be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used in all the drawings to denote the same or similar parts. Furthermore, although the terminology used herein is selected from commonly known and used terms, some terms mentioned in this specification may have been chosen by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of the description herein. Moreover, the invention should be understood not only by the actual terminology used, but also by the meaning implied by each term. Also, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale.

[0041] See Figure 1 This invention provides a test method for verifying the performance of mechanical plugs on heat exchanger tubes, the method comprising the following steps:

[0042] S1. Perform hydrostatic pressure test, cyclic test and thermal shock test on the plug test piece; perform corrosion test on the plug test piece; perform overpressure test on the plug test piece and record the failure value;

[0043] S2. After the hydrostatic test, cyclic test and thermal shock test are completed, determine whether the plug test piece meets the temperature and pressure test acceptance criteria; after the corrosion test is completed, determine whether the plug test piece meets the corrosion test acceptance criteria; if both the temperature and pressure test acceptance criteria and the corrosion test acceptance criteria are met, the plug test piece is deemed to be qualified; if either the temperature and pressure test acceptance criteria or the corrosion test acceptance criteria is not met, the plug test piece is deemed to be unqualified.

[0044] It should be noted that the thermo-pressure test includes hydrostatic pressure test, cyclic test and thermal shock test. Therefore, the thermo-pressure test acceptance criteria are the criteria for accepting the hydrostatic pressure test, cyclic test and thermal shock test.

[0045] See Figure 1 As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention, the cyclic test includes a constant temperature and pressure cyclic test, a temperature and pressure dual cyclic test, and a constant pressure and temperature cyclic test; the acceptance criteria for the temperature and pressure test include the requirement for helium leakage after the water pressure test.

[0046] It should be noted that the thermo-pressure test acceptance criteria include the helium leakage requirement after the hydrostatic test. If the helium leakage requirement after the hydrostatic test is met, then the thermo-pressure test acceptance criteria are met, indicating that the plug test piece has passed the hydrostatic test, thermo-pressure cycle test, temperature and pressure dual cycle test, constant pressure temperature cycle test, and thermal shock test.

[0047] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the temperature and pressure test acceptance criteria also include the maximum allowable movement distance requirement. If both the helium leakage requirement after water pressure and the maximum allowable movement distance requirement are met, then the temperature and pressure test acceptance criteria are met.

[0048] It should be noted that the thermo-pressure test acceptance criteria include helium leakage requirements after the hydrostatic test, while the maximum allowable movement distance requirement is optional.

[0049] When the thermo-pressure test acceptance criteria include both the helium leakage requirement after the hydrostatic test and the maximum allowable movement distance requirement, the thermo-pressure test acceptance criteria are considered to be met only when both the helium leakage requirement after the hydrostatic test and the maximum allowable movement distance requirement are met simultaneously, indicating that the plug test piece has passed the hydrostatic test, cyclic test and thermal shock test.

[0050] This invention provides a test method for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes. It uses transient operating conditions of a nuclear power plant (start-up, temporary shutdown, transient temperature changes within the reactor, etc.) as input. Performance evaluation tests include hydrostatic testing, pressure cycling, temperature cycling, pressure-temperature dual cycling, and corrosion testing. Specific tests include hydrostatic testing, overpressure testing, isothermal-pressure cycling testing, isothermal-temperature cycling testing, temperature-pressure dual cycling testing, and corrosion testing. Test conditions must encompass all actual operating conditions. This method enables rapid performance verification of mechanical plugs on heat transfer tubes in nuclear power plant steam generators.

[0051] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the test conditions of the hydrostatic test are set to be maintained at 1.5 times the design pressure or 3 times the maximum pressure difference of the tube sheet for 1 hour.

[0052] The hydrostatic pressure test was performed on the primary and secondary sides of the plug test piece, respectively.

[0053] The acceptance criteria for the hydrostatic test are set as follows: after the primary and secondary hydrostatic tests are completed on the plug test piece, a helium leak test is performed respectively, which must meet the requirement that the helium leakage rate is less than the set value (10^(-8) Pa·m^3 / s).

[0054] The hydrostatic pressure test is described below:

[0055] ① Establish test conditions: Hold pressure for 1 hour at 1.5 times the design pressure or 3 times the maximum pressure difference of the tube sheet.

[0056] ② The test was conducted using a hydrostatic testing device, and hydrostatic tests were performed on the primary and secondary sides of the plug test piece, respectively.

[0057] ③ Acceptance criteria: After the primary and secondary hydrostatic pressure tests are completed, the plug test piece shall be subjected to a helium leak test using a helium leak meter. It must meet the helium leak requirement (helium leak rate < 10^(-8) Pa·s).

[0058] m^3 / s).

[0059] If the acceptance criteria are met, subsequent performance evaluation tests will be conducted. If the acceptance criteria are not met, the performance evaluation of the plug test piece will fail.

[0060] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention, the overpressure test involves slowly pressurizing the secondary side of the plug test piece until the plug test piece completely falls off or the tube wall bursts, and recording the pressure value of the sealing failure.

[0061] The description of the aforementioned overpressure test is as follows:

[0062] ① The test is conducted using a water pressure testing device. The secondary side port of the plug test piece is connected to the water pressure testing device 1, and the secondary side is slowly pressurized until the plug test piece completely falls off or the pipe wall bursts.

[0063] ② Record the pressure value at which the seal fails.

[0064] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the test conditions of the isothermal pressure cyclic test are set as follows: the primary side test temperature is the primary side design temperature, and the cyclic test pressure range is the sum of the primary side design pressure and the maximum pressure difference between the primary side and the secondary side; the secondary side test temperature is the secondary side design temperature, and the cyclic test pressure range is the sum of the saturated water pressure at the secondary side design temperature and the maximum pressure difference between the secondary side and the primary side; the number of cycles is the number of transients that can encompass the design transients exceeding the set pressure fluctuation range.

[0065] The plug test piece follows the principle of first testing then second testing, and isothermal pressure cycling tests are performed according to the test conditions. Preferably, an acceptance process can be set after the isothermal pressure cycling test. The acceptance criteria for the isothermal pressure cycling test are set as follows: after the plug test piece completes the isothermal pressure cycling test, a hydrostatic test is performed, and a helium leak test is performed. The helium leakage rate must meet the requirement of helium leakage rate <10^(-8) Pa·m^3 / s after the hydrostatic test.

[0066] The isothermal pressure cycling test is described as follows:

[0067] ① Establish test conditions: The primary side test temperature is the primary side design temperature, and the cyclic test pressure range is the sum of the primary side design pressure and the maximum pressure difference between the primary and secondary sides; the secondary side test temperature is the secondary side design temperature, and the cyclic test pressure range is the sum of the saturated water pressure at the secondary side design temperature and the maximum pressure difference between the secondary and primary sides; the number of cycles is the number of transients that can encompass the range of meaningful pressure fluctuations specified in ASME B&PVC-Ⅲ-1-NB-3222.4(d)(2) during the design transient.

[0068] ② The test was conducted using a constant temperature and pressure cycling test equipment. For the plug test pieces after the hydrostatic test, the principle of first test and then second test was followed, and constant temperature and pressure cycling tests were carried out according to the test conditions.

[0069] ③ Acceptance criteria: After the plug test piece completes the constant temperature and pressure cycle test, a hydrostatic test is conducted using water pressure testing equipment 1, and a helium leak test is conducted using a helium leak meter. It must meet the helium leakage requirements after the hydrostatic test (helium leakage rate < 10^(-8) Pa·m^3 / s).

[0070] If the acceptance criteria are met, subsequent performance evaluation tests will be conducted. If the acceptance criteria are not met, the performance evaluation of the plug test piece will fail.

[0071] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention, the test conditions of the temperature and pressure dual-cycle test are set as follows: the medium is boron-lithium water, the water chemical parameters are adjusted to be consistent with the primary side water chemical parameters of the steam generator design conditions, the temperature is heated to the primary side design temperature (350°C) at a temperature gradient of 58-120°C / h, the pressure is increased from atmospheric pressure to the primary side design pressure (from 1MPa to 17.2MPa) as the temperature rises, the temperature is held at the highest temperature for 3 hours and the highest pressure is maintained, the temperature is cooled to 50°C at a cooling rate of more than 58°C / h, and the pressure is reduced to atmospheric pressure as the temperature drops. During this period, the pressure is always kept higher than the saturated vapor pressure at the corresponding temperature to complete one cycle, and the number of cycles is at least 4.

[0072] A temperature and pressure dual-cycle test was conducted on the primary side of the plug test piece according to the test conditions.

[0073] Preferably, an acceptance process can be set after the temperature and pressure dual-cycle test. The acceptance criteria for the temperature and pressure dual-cycle test are set as follows: after the plug test piece completes the constant temperature and pressure cycle test, a hydrostatic test is performed, and a helium leak test is performed. The helium leakage rate must meet the helium leakage requirement after the hydrostatic test of <10^(-8)Pa·m^3 / s.

[0074] The temperature and pressure dual-cycle test is described as follows:

[0075] ① Establish test conditions: The medium is boron-lithium water. Adjust the water chemical parameters to be consistent with the primary side water chemical parameters of the steam generator under design conditions. Heat to 350℃ with a temperature gradient of 58-120℃ / h. The pressure increases from 1 to 17.2MPa with the temperature. Hold the temperature at the highest point for 3 hours while maintaining the highest pressure. Cool to 50℃ at a cooling rate greater than 58℃ / h. The pressure decreases to atmospheric pressure with the temperature. During this period, ensure that the pressure is always higher than the saturated vapor pressure at the corresponding temperature. Complete one cycle. The number of cycles should be at least 4.

[0076] ② The test was conducted using a temperature and pressure cycling test equipment. After the hydrostatic test and the constant temperature and pressure cycling test, the primary side of the plug test piece was subjected to a temperature and pressure double cycle test according to the test conditions.

[0077] ③ Acceptance criteria: After the plug test piece completes the constant temperature and pressure cycle test, a hydrostatic test is conducted using water pressure testing equipment 1, and a helium leak test is conducted using a helium leak meter. It must meet the helium leakage requirements after the hydrostatic test (helium leakage rate < 10^(-8) Pa·m^3 / s).

[0078] If the acceptance criteria are met, subsequent performance evaluation tests will be conducted. If the acceptance criteria are not met, the performance evaluation of the plug test piece will fail.

[0079] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention, the test conditions of the constant pressure temperature cycling test are set as follows: the primary side medium is boron-lithium water, the secondary side medium is deionized water, the water chemical parameters are adjusted to be consistent with the primary and secondary side water chemical parameters under the design conditions of the steam generator, the primary side test pressure is taken as the primary side design pressure, the temperature cycling range is from room temperature to the primary side design temperature, the number of cycles takes into account the number of heating and cooling cycles of the power plant, and according to the design transient, the number of combined heating and cooling transient cycles of the power plant across the entire temperature range is included.

[0080] For the plug test pieces, the principle of first testing and then testing twice should be followed, and constant pressure and temperature cycling tests should be carried out according to the test conditions.

[0081] Preferably, an acceptance process can be set after the constant pressure and temperature cycling test. The acceptance criteria for the constant pressure and temperature cycling test are set as follows: after the plug test piece completes the constant temperature and pressure cycling test, a hydrostatic test is performed, followed by a helium leak test, which must meet the requirement that the helium leakage rate is <10^(-8) Pa·

[0082] Requirements for helium leakage after a hydrostatic test at m^3 / s.

[0083] The constant pressure temperature cycling test is described as follows:

[0084] ① Establish test conditions: The primary side medium is boron-lithium water, and the secondary side medium is deionized water. Adjust the water chemical parameters to be consistent with the design conditions of the steam generator for both the primary and secondary sides. The test pressure on the primary side is the design pressure of the primary side. The temperature cycling range is from room temperature to the design temperature of the primary side. The number of cycles takes into account the number of heating and cooling cycles of the power plant. Based on the design transients, the number of combined heating and cooling transients across the entire temperature range of the power plant is included.

[0085] ② The test was conducted using a temperature and pressure cycling test equipment. For the plug test pieces that had undergone hydrostatic pressure test, constant temperature and pressure cycling test and temperature and pressure dual cycling test, the principle of first test and then second test was followed, and constant pressure and temperature cycling test was carried out according to the test conditions.

[0086] ③ Acceptance criteria: After the plug test piece completes the constant temperature and pressure cycle test, a hydrostatic test is conducted using water pressure testing equipment 1, and a helium leak test is conducted using a helium leak meter. It must meet the helium leakage requirements after the hydrostatic test (helium leakage rate < 10^(-8) Pa·m^3 / s).

[0087] If the acceptance criteria are met, subsequent performance evaluation tests will be conducted. If the acceptance criteria are not met, the performance evaluation of the plug test piece will fail.

[0088] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the test conditions of the thermal shock test are set as follows: the temperature change range is from room temperature to the primary side design temperature, the temperature rise range is from room temperature to the primary side design temperature, after removal, the air cooling device is used to cool to 150°C, the spray cooling device is used to cool from 150°C to 80°C, and the spray cooling device is used to cool from 80°C to room temperature, and the number of cycles is 10.

[0089] The plug test specimens were subjected to thermal shock tests according to the test conditions.

[0090] Preferably, an acceptance process can be set after the thermal shock test. The acceptance criteria for the thermal shock test are set as follows: after the plug test piece completes the constant temperature and pressure cycle test, a hydrostatic test is performed, and a helium leak test is performed. The helium leakage rate must meet the requirement of helium leakage rate <10^(-8) Pa·m^3 / s after the hydrostatic test.

[0091] The thermal shock test is described below:

[0092] ① Establish test conditions: The temperature range is from room temperature to the primary side design temperature, the temperature rise range is from room temperature to the primary side design temperature, after removal, the air cooling device is used to cool to 150℃, the spray cooling device is used to cool from 150℃ to 80℃, and the spray cooling device is used to cool from 80℃ to room temperature. The number of cycles is 10.

[0093] ② The test was conducted using thermal shock testing equipment. The plug test pieces, after undergoing hydrostatic pressure test, constant temperature and pressure cycle test, temperature and pressure dual cycle test, and constant pressure and temperature cycle test, were subjected to thermal shock test according to the test conditions.

[0094] ③ Acceptance criteria: After the plug test piece completes the constant temperature and pressure cycle test, a hydrostatic test is conducted using water pressure testing equipment 1, and a helium leak test is conducted using a helium leak meter. It must meet the helium leakage requirements after the hydrostatic test (helium leakage rate < 10^(-8) Pa·m^3 / s).

[0095] If the acceptance criteria are met, subsequent performance evaluation tests will be conducted. If the acceptance criteria are not met, the performance evaluation of the plug test piece will fail.

[0096] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the helium leakage requirement after the hydrostatic test is: the plug test piece is subjected to a hydrostatic test and a helium leak test, and the helium leakage rate after the hydrostatic test must meet the requirement that the helium leakage rate is less than the set value (10^(-8) Pa·m^3 / s).

[0097] The maximum allowable movement distance requirement is: the movement distance of the plug test piece must be less than the maximum allowable movement distance requirement.

[0098] As a preferred embodiment of the test method for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the test conditions of the corrosion test are set as follows: the medium is a degassed NaOH solution with a concentration of 100±3g / L, the temperature is 350±3℃, the pressure is 152±8bar (the pressure error depends on the temperature error), and the test time is at least 1000h.

[0099] Corrosion tests were conducted on the plug test specimens according to the test conditions;

[0100] The corrosion test acceptance criteria are set as follows: after the corrosion test is completed, the plug test piece undergoes a hydrostatic test and a helium leak test, which must meet the helium leakage requirement of <10^(-8) Pa·m^3 / s; and the plug test piece is cut along the center line of the end face by wire cutting, and after grinding and polishing, the cross-section of the plug test piece tube is observed, focusing on the stress corrosion morphology on the inner side of the tube cross-section. If no obvious corrosion cracks are observed in the magnified cross-sectional view, it passes; otherwise, it fails.

[0101] The corrosion test is described below:

[0102] ① Establish test conditions: The medium is a degassed NaOH solution with a concentration of 100±3g / L, the temperature is 350±3℃, the pressure is 152±8bar (pressure error depends on temperature error), and the test time is at least 1000h.

[0103] ② The test was conducted using corrosion testing equipment. For the plug test pieces that had undergone hydrostatic pressure testing, corrosion testing was carried out according to the test conditions.

[0104] ③ Acceptance Criteria: After the corrosion test of the plug test piece is completed, a hydrostatic test is conducted using water pressure testing equipment 1, and a helium leak test is performed using a helium leak meter. The helium leak requirement must be met (helium leak rate < 10^(-8) Pa·m^3 / s). The plug test piece is then cut along the center line of the end face using wire cutting. After grinding and polishing, the cross-section of the plug test piece is observed, with a focus on the stress corrosion morphology on the inner side of the cross-section. The cross-sectional view is magnified using a 200x microscope or equivalent method. If no obvious corrosion cracks are observed, the test piece passes; otherwise, it fails.

[0105] In the above tests, the order of the constant temperature and pressure cycle test, temperature and pressure dual cycle test, constant pressure and temperature cycle test, and thermal shock test can be adjusted.

[0106] Plug test pieces that have passed the hydrostatic pressure test, constant temperature and pressure cycle test, temperature and pressure dual cycle test, constant pressure and temperature cycle test, thermal shock test, and corrosion test and meet all acceptance standards will pass the performance evaluation; otherwise, they will not pass.

[0107] See Figures 2-4 The present invention also provides a test device for verifying the performance of mechanical plugs of heat exchanger heat transfer tubes. The test device is used to perform the test method for verifying the performance of mechanical plugs of heat exchanger heat transfer tubes as described above. The test device includes a water pressure test device 1, a constant temperature and pressure cycle test device 2, a temperature and pressure cycle test device 3, a thermal shock test device 4, and a corrosion test device 5.

[0108] Hydrostatic testing equipment 1 is used for hydrostatic testing and overpressure testing;

[0109] The isothermal pressure cycling test equipment 2 is used to conduct isothermal pressure cycling tests;

[0110] Temperature and pressure cycling test equipment 3 is used to perform temperature and pressure dual-cycle tests and constant pressure temperature cycling tests;

[0111] Thermal shock testing equipment 4 is used to conduct thermal shock tests;

[0112] Corrosion testing equipment 5 is used to conduct corrosion tests.

[0113] See Figure 2 As a preferred embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the water pressure test equipment 1 includes a high-pressure water supply circuit 10 and a data acquisition and control system 11.

[0114] The high-pressure water supply circuit 10 includes a water supply branch 12 and a return water branch 13. The plug test piece 15 is connected between the water supply branch 12 and the return water branch 13. The water supply branch 12 includes a water tank 121, a low-pressure booster pump 123, a high-pressure booster pump 124, and a pressure sensor 127, which are connected in sequence along the water flow direction. The return water branch 13 includes an electromagnetic pressure relief valve 131. The high-pressure booster pump 124 is driven by air pressure, and its drive pipeline 14 is equipped with a compressed air source 141 and a solenoid valve 144.

[0115] The data acquisition and control system 11 is electrically or communicatively connected to the solenoid valve 144, the solenoid pressure relief valve 131, and the pressure sensor 127.

[0116] exist Figure 2 In this embodiment, the hydrostatic testing equipment 1 includes a high-pressure water supply circuit 10 and a data acquisition and control system 11. The high-pressure water supply circuit 10 includes a water supply branch 12 and a return water branch 13. The water supply branch 12 includes a water tank 121, a filter 122, a low-pressure booster pump 123, a high-pressure booster pump 124, a check valve 125, a high-pressure gauge 126, and a pressure sensor 127, which are connected in sequence. The return water branch 13 includes an electromagnetic pressure relief valve 131 and a safety valve 132 connected in parallel with it. The high-pressure booster pump 124 is driven by air pressure. The drive pipeline 14 of the high-pressure booster pump 124 is equipped with a compressed air source 141, a filter 122, a compressed air switch 143, and a solenoid valve 144. The data acquisition and control system 11 is connected to the solenoid valve 144, the electromagnetic pressure relief valve 131, and the pressure sensor 127. The data acquisition and control system 11 controls the opening of the solenoid valve 144 to achieve pressure control of the compressed air source, thereby controlling the pressure of the water supply branch 12; the data acquisition and control system 11 acquires the pressure value measured by the pressure sensor 127 and adjusts the opening of the solenoid valve 144 according to the acquired pressure value; the data acquisition and control system 11 controls the opening of the solenoid pressure relief valve 131 to achieve pressure holding and pressure relief of the plug test piece 15.

[0117] The working principle of the above-mentioned hydrostatic testing equipment 1 is explained as follows:

[0118] Water in tank 121, after being filtered by filter 122, is driven by low-pressure booster pump 123 to flow through high-pressure booster pump 124, check valve 125, high-pressure gauge 126, and pressure sensor 127, before flowing into plug test piece 15. Electromagnetic pressure relief valve 131 is closed under the control of data acquisition and control system 11. Once the pressure reaches a certain value, the opening of solenoid valve 144 is controlled by data acquisition and control system 11 to adjust the water supply branch 12 to increase the pressure to the specified level. After reaching the specified pressure, data acquisition and control system 11 controls solenoid valve 144 to close, initiating pressure maintenance. After the test is completed, data acquisition and control system 11 controls solenoid pressure relief valve 131 to open, and water in plug test piece 15 flows back into tank 121 through return water branch 13.

[0119] See Figure 3 As a preferred embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention, the constant temperature and pressure cycle test equipment 2 includes a pressure regulating circuit 20, a high temperature vessel 21, a data acquisition and control system 11 and a pressure monitoring module 23.

[0120] The pressure regulating circuit 20 includes a water supply branch 12 and a water return branch 13. The water supply branch 12 includes a water tank 121, a high-pressure pump 243 and a solenoid valve 144 connected in sequence along the water flow direction. The water return branch 13 includes a solenoid pressure relief valve 131.

[0121] The plug test piece 15 is placed in the high-temperature reactor 21, with one end connected between the water supply branch 12 and the return water branch 13, and the other end connected to the pressure monitoring module 23; the high-temperature reactor 21 is equipped with a thermocouple 210;

[0122] The data acquisition and control system 11 is electrically or communicatively connected to the thermocouple 210, the pressure monitoring module 23, the solenoid valve 144, and the solenoid pressure relief valve 131.

[0123] exist Figure 3 In this embodiment, the constant temperature and pressure cycling test equipment 2 includes a pressure regulating circuit 20, a high-temperature reactor 21, a data acquisition and control system 11, and a pressure monitoring module 23. The pressure regulating circuit 20 includes a water supply branch 12 and a return water branch 13. The water supply branch 12 includes a water tank 121, a filter 122, a high-pressure pump 243, a pressure stabilizing tank 244, a first ball valve 245, a first solenoid valve 246, and a check valve 125 connected in sequence. The return water branch 13 includes a second ball valve 251, a second solenoid valve 252, a condenser 253, a T-type filter 254, a third solenoid valve 255, and a third ball valve 256 connected in sequence. In this embodiment, the solenoid valve 144 is the first solenoid valve 246, and the electromagnetic pressure relief valve 131 is the second solenoid valve 252 and the third solenoid valve 255.

[0124] The plug test piece 15 is placed in the high-temperature reactor 21, with one end connected between the water supply branch 12 and the return water branch 13, and the other end connected to the pressure monitoring module 23. A safety valve 132, a pressure gauge 258, and a pressure transmitter 259 are installed in parallel between the condenser 253 and the T-type filter 254. The data acquisition and control system 11 is connected to the first thermocouple 211, the second thermocouple 212, the third thermocouple 213, and the pressure monitoring module 23. The data acquisition and control system 11 is also connected to the first solenoid valve 246, the second solenoid valve 252, and the third solenoid valve 255.

[0125] The data acquisition and control system 11 controls the temperature of the high-temperature reactor 21 to provide specified temperature conditions for the plug test piece 15. The high-temperature reactor 21 is equipped with a first thermocouple 211, a second thermocouple 212, and a third thermocouple 213. The data acquisition and control system 11 controls the opening of the first solenoid valve 246, the second solenoid valve 252, and the third solenoid valve 255. The data acquisition and control system 11 collects the pressure value measured by the pressure monitoring module 23 and the temperature value measured by the first thermocouple 211, the second thermocouple 212, and the third thermocouple 213.

[0126] The working principle of the above-mentioned constant temperature pressure cycle test equipment 2 is explained as follows:

[0127] The data acquisition and control system 11 controls the first solenoid valve 246 to open and the second solenoid valve 252 and the third solenoid valve 255 to close. Water in the water tank 121 flows out through the filter 122 and is driven by the high-pressure pump 243 to flow through the pressure stabilizing tank 244, the first ball valve 245, the first solenoid valve 246, and the check valve 125, before flowing into the plug test piece 15. The plug test piece 15 is installed inside the high-temperature reactor 21. When the readings of the first thermocouple 211, the second thermocouple 212, and the third thermocouple 213 are basically the same, the plug test piece... After the pressure monitoring module 23 monitors the pressure and the specified pressure is reached, the data acquisition and control system 11 controls the first solenoid valve 246 to close and begin pressure holding. After the specified time is reached, the data acquisition and control system 11 controls the second solenoid valve 252 and the third solenoid valve 255 to open and begin pressure release. The water in the plug test piece 15 flows through the second ball valve 251, the second solenoid valve 252, the condenser 253, the T-type filter 254, the third solenoid valve 255, and the third ball valve 256 before flowing back to the water tank 121, completing one main circulation.

[0128] See Figure 4 As a preferred embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube of the present invention, the temperature and pressure cycle test equipment 3 includes a pressure regulating circuit 20, a water chemistry circuit 31, a high temperature and high pressure vessel 32, a cooling system 33, a data acquisition and control system 11, and a pressure monitoring module 23.

[0129] The pressure regulating circuit 20 includes a water supply branch 12 and a return water branch 13. The water supply branch 12 includes a water tank 121, a high-pressure pump 243, and a solenoid valve 144 connected in sequence along the water flow direction. The return water branch 13 includes a solenoid pressure relief valve 131.

[0130] The water chemistry circuit 31 includes a high-pressure metering pump 311, a dosing point 314, a peristaltic pump 315, a gas source solenoid valve 318, and a hydrogen source 317, which are connected in sequence along the water flow direction.

[0131] Cooling system 33 includes heat exchanger 330, which is connected between water supply branch 12 and return branch 13;

[0132] The plug test piece 15 is placed in the high-temperature and high-pressure reactor 32, with one end connected to the heat exchanger 330 and the other end connected to the pressure monitoring module 23; the high-temperature and high-pressure reactor 32 is equipped with a thermocouple 210;

[0133] The data acquisition and control system 11 is electrically or communicatively connected to thermocouple 210, pressure monitoring module 23, solenoid valve 144, solenoid pressure relief valve 131 and gas source solenoid valve 318.

[0134] exist Figure 4 In this embodiment, the temperature and pressure cycling test equipment 3 includes a pressure regulating circuit 20, a water chemistry circuit 31, a high-temperature and high-pressure reactor 32, a cooling system 33, a data acquisition and control system 11, and a pressure monitoring module 23. The pressure regulating circuit 20 includes a water supply branch 12 and a return water branch 13. The water supply branch 12 includes a water tank 121, a filter 122, a high-pressure pump 243, a first ball valve 245, a first solenoid valve 246, and a check valve 125 connected in sequence. A first safety valve 324 is connected in parallel to the water supply branch 12. The return water branch 13 includes a condenser 253, a T-type filter 254, a second solenoid valve 252, and a second ball valve 251 connected in sequence. In this embodiment, the solenoid valve 144 is the first solenoid valve 246, and the solenoid pressure relief valve 131 is the second solenoid valve 252.

[0135] The water chemistry circuit 31 includes a high-pressure metering pump 311, a high-precision conductivity meter 312, and a pH meter.

[0136] 313, dosing point 314, peristaltic pump 315, dissolved oxygen meter 316, hydrogen source 317, and gas source solenoid valve 318. The flow rate of the high-pressure metering pump 311 is matched with the loop volume to ensure a water exchange rate greater than 1 time / hour. The cooling system 33 includes a heat exchanger 330. The cooling system 33 is connected between the water supply branch 12 and the return water branch 13. The plug test piece 15 is placed in the high-temperature and high-pressure reactor 32, with one end connected to the heat exchanger 330 and the other end connected to the pressure monitoring module 23. The high-temperature and high-pressure reactor 32 is equipped with a first safety valve 324, a first pressure gauge 325, and a first pressure transmitter 326 connected in parallel. A second safety valve 375, a second pressure gauge 376, and a second pressure transmitter 377 are connected in parallel between the condenser 253 and the T-type filter 254. The data acquisition and control system 11 is connected to the first thermocouple 211, the second thermocouple 212, the third thermocouple 213, and the pressure monitoring module 23. The data acquisition and control system 11 is also connected to the first solenoid valve 246, the second solenoid valve 252, and the gas source solenoid valve 318.

[0137] The data acquisition and control system 11 controls the temperature of the high-temperature and high-pressure reactor 32 to provide specified temperature conditions for the plug test piece 15. The high-temperature and high-pressure reactor 32 is equipped with a first thermocouple 211, a second thermocouple 212, and a third thermocouple 213. The data acquisition and control system 11 controls the opening of the first solenoid valve 246, the second solenoid valve 252, and the gas source solenoid valve 318. The data acquisition and control system 11 collects the pressure value measured by the pressure monitoring module 23 and the temperature values ​​measured by the first thermocouple 211, the second thermocouple 212, and the third thermocouple 213. The data acquisition and control system 11 collects the measurement values ​​of the high-precision conductivity meter 312 and the pH meter 313. The data acquisition and control system 11 controls the peristaltic pump 315 to adjust the conductivity of the water tank 121 to control the ion concentration. The data acquisition and control system 11 collects the measurement value of the dissolved oxygen meter 316. When the oxygen content is high, the data acquisition and control system 11 controls the gas source solenoid valve 318 to open, introducing hydrogen gas to remove oxygen from the circuit.

[0138] The aforementioned temperature and pressure cycling test equipment 3 can be used to simulate secondary-side temperature and pressure cycles and primary-side temperature and pressure cycles. Its working principle is explained as follows:

[0139] During the simulation of secondary side temperature and pressure cycling: Water tank 121 contains deionized water, used to simulate the secondary side medium of the steam generator. The data acquisition and control system 11 controls the first solenoid valve 246 to open and the second solenoid valve 252 to close. Water from tank 121 flows out through filter 122 and is driven by high-pressure pump 243 to flow through the first ball valve 245, the first solenoid valve 246, and the check valve 125, into the secondary side of the plug test piece 15. The plug test piece 15 is installed inside the high-temperature and high-pressure reactor 32, fixing the secondary side of the plug test piece 15 exposed inside the high-temperature and high-pressure reactor 32. The high-temperature and high-pressure reactor 32 provides a specified temperature for the plug test piece 15. High-pressure pump 243... The pressure is provided by module 43. After the pressure monitoring module 23 monitors the plug test piece 15 and it reaches the specified pressure, the data acquisition and control system 11 controls the first solenoid valve 246 to close and begin pressure holding. After the specified time is reached, the data acquisition and control system 11 controls the second solenoid valve 252 to open and begin pressure release. The water in the plug test piece 15 flows through the heat exchanger 330 for cooling, then flows through the condenser 253, T-type filter 254, second solenoid valve 252, and second ball valve 251 before flowing back to the water tank 121, completing one main cycle. The equipment can achieve single-temperature cycle and pressure change with temperature operation.

[0140] During the simulation of primary-side temperature and pressure cycling: The data acquisition and control system 11 controls the peristaltic pump 315 to add chemicals to the water tank 121, adjusting the ion concentration of the water. After adding chemicals, the water tank 121 contains boron-lithium water of a certain concentration, used to simulate the primary-side medium of the steam generator. The data acquisition and control system 11 controls the first solenoid valve 246 to open and the second solenoid valve 252 to close. After the water in the water tank 121 flows out through the filter 122, it is driven by the high-pressure pump 243 to flow through the first ball valve 245, the first solenoid valve 246, and the check valve 125, flowing into the primary side of the plug test piece 15. The plug test piece 15 is installed in the high-temperature and high-pressure reactor 32, fixing the primary side of the plug test piece 15 exposed inside the reactor. The high-temperature and high-pressure reactor 32 provides a specified temperature for the plug test piece 15, and the high-pressure pump 243 pumps... After the pressure monitoring module 23 monitors the plug test piece 15 and it reaches the specified pressure, the data acquisition and control system 11 controls the first solenoid valve 246 to close and begin pressure holding. After a specified time, the data acquisition and control system 11 controls the second solenoid valve 252 to open and begin pressure release. The water in the plug test piece 15 flows through the heat exchanger 330 for cooling, then flows through the condenser 253, T-type filter 254, second solenoid valve 252, and second ball valve 251 before flowing back to the water tank 121, completing one main cycle. The equipment can achieve single-temperature cycling and pressure-dependent operation.

[0141] See Figure 5 As a preferred embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the thermal shock test equipment 4 includes a high temperature furnace 41, a cooling system 33 and a data acquisition and control system 11.

[0142] The cooling system 33 includes an air cooling device 331, a spray cooling device 332 and a spray cooling device 333, and a thermocouple 210 is installed inside the high-temperature furnace 41.

[0143] The data acquisition and control system 11 is electrically or communicatively connected to thermocouple 210 and test thermocouple 151.

[0144] In one embodiment of the test apparatus for verifying the performance of mechanical plugs in heat exchanger tubes of the present invention, the thermal shock test equipment 4 includes a high-temperature furnace 41, a cooling device, and a data acquisition and control system. The cooling system 33 includes an air-cooling device 331, a spray cooling device 332, and a spray cooling device 333. A thermocouple 210 is installed inside the high-temperature furnace 41 to monitor the temperature inside the furnace. A test thermocouple 151 is connected to the plug test piece 15 to monitor the temperature of the plug test piece 15 in real time throughout the thermal shock test. In use, the plug test piece, after being heated in the high-temperature furnace 41, is sequentially cooled by the air-cooling device 331, the spray cooling device 332, and the spray cooling device 333 to conduct the thermal shock test.

[0145] The working principle of the above-mentioned thermal shock testing equipment 4 is explained as follows:

[0146] The high-temperature furnace 41 provides the required temperature conditions for the test, the cooling system 33 provides segmented cooling conditions, and the data acquisition and control system collects the values ​​measured by the thermocouple 210. Under normal pressure, the high-temperature furnace 41 is used to heat the plug test piece 15 to the specified temperature. After the temperature holding period, the cooling device is used to cool the plug test piece 15 in segments. After cooling to room temperature, the plug test piece 15 is placed back into the high-temperature furnace 41 for the next heating, completing one cycle.

[0147] exist Figure 5 In this embodiment, the plug test piece 15 is first heated in a high-temperature furnace 41, then cooled for the first time by an air-cooling device 331, followed by a second cooling by a spray cooling device 332, and finally a third cooling by a spray cooling device 333. This process of heating and three-stage cooling is used to obtain the thermal shock resistance of the plug test piece 15. In this embodiment, the thermocouple 210 includes a first thermocouple 211, a second thermocouple 212, and a third thermocouple 213.

[0148] See Figure 6 As a preferred embodiment of the test device for verifying the performance of the mechanical plug of the heat exchanger tube of the present invention, the corrosion test equipment 5 includes a reaction vessel 51 and a data acquisition and control system 11.

[0149] The data acquisition and control system 11 is electrically or communicatively connected to the reactor 51.

[0150] In one embodiment of the test apparatus for verifying the performance of mechanical plugs on heat exchanger tubes of the present invention, the corrosion test equipment 5 includes a reaction vessel 51 and a data acquisition and control system 11. The data acquisition and control system 11 controls the reaction vessel 51 to provide specified temperature conditions for the plug test piece 15.

[0151] exist Figure 6 In this embodiment, the reactor 51 is electrically connected to the pressure sensor 127 and the temperature sensor 511 to monitor the temperature and pressure inside the reactor 51.

[0152] The corrosion testing equipment 5 described above can be used to simulate primary and secondary corrosion. Its working principle is explained below:

[0153] During the simulation of primary side corrosion: the plug test piece 15 is installed on the heat transfer tube simulator, the end cap is installed on one side and sealed and welded, a 10% NaOH solution is prepared and placed in the reactor 51 together with the plug test piece 15, and the reactor 51 is sealed and kept at temperature and pressure for a specified time.

[0154] In simulating secondary corrosion: the heat transfer tube simulator is removed from the plug test piece 15, the end caps are installed on both sides and sealed and welded, a 10% NaOH solution is prepared and placed in the reactor 51 together with the plug test piece 15, and the reactor 51 is sealed and kept at temperature and pressure for a specified time.

[0155] The apparatus and method described in this invention are not only applicable to heat transfer tubes in nuclear power plant steam generators, but can also be extended to verifying the sealing performance, pressure resistance, and thermal shock resistance of mechanical plugs in heat transfer tubes of other heat exchangers employing tube bundle structures (such as those in chemical, power, and shipbuilding industries). The experimental apparatus and method for verifying the performance of mechanical plugs in heat exchanger heat transfer tubes of this invention have the following advantages:

[0156] I. This invention supplements and refines the verification test requirements that are not clearly defined in existing specifications and standards, including hydrostatic pressure test, overpressure test, constant temperature and pressure cycle test, constant pressure and temperature cycle test, temperature and pressure dual cycle test, thermal shock test and corrosion test.

[0157] II. This invention establishes a test device and method that can scientifically and comprehensively verify the performance of mechanical plugs for heat transfer tubes, and provides an executable and standardized test procedure and scheme.

[0158] Third, this invention can quickly verify the performance of the plug. By reasonably setting up the heating, cooling and control system of the test circuit, the temperature cycle test cycle can be controlled at an efficient level of 500 times / month.

[0159] Fourth, by adopting a data acquisition and control integrated module, it is possible to achieve rapid simulation of different working conditions and precise control of test parameters.

[0160] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A test method for verifying the performance of mechanical plugs on heat exchanger tubes, characterized in that, The method includes the following steps: S1. Perform hydrostatic pressure test, cyclic test and thermal shock test on the plug test piece; perform corrosion test on the plug test piece; perform overpressure test on the plug test piece and record the failure value; S2. After the hydrostatic test, cyclic test and thermal shock test are completed, determine whether the plug test piece meets the temperature and pressure test acceptance criteria; after the corrosion test is completed, determine whether the plug test piece meets the corrosion test acceptance criteria; if both the temperature and pressure test acceptance criteria and the corrosion test acceptance criteria are met, the plug test piece is deemed to be qualified; if either the temperature and pressure test acceptance criteria or the corrosion test acceptance criteria is not met, the plug test piece is deemed to be unqualified.

2. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 1, characterized in that, The cyclic tests include constant temperature and pressure cyclic tests, temperature and pressure dual cyclic tests, and constant pressure and temperature cyclic tests; the acceptance criteria for the temperature and pressure tests include helium leakage requirements after the hydrostatic test.

3. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 2, characterized in that, The temperature and pressure test acceptance criteria also include the maximum allowable movement distance requirement. If both the helium leakage requirement after water pressure and the maximum allowable movement distance requirement are met, then the temperature and pressure test acceptance criteria are met.

4. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 1, characterized in that, The hydrostatic pressure test conditions are set as follows: pressure is maintained for 1 hour at 1.5 times the design pressure or 3 times the maximum pressure difference of the tube sheet. The hydrostatic pressure test was performed on the primary and secondary sides of the plug test piece, respectively. The acceptance criteria for the hydrostatic test are set as follows: after the primary and secondary hydrostatic tests are completed on the plug test piece, a helium leak test is performed respectively, and the helium leak rate must meet the requirement of being less than the set value.

5. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 1, characterized in that, The overpressure test involves slowly pressurizing the secondary side of the plug test piece until the plug test piece completely falls off or the pipe wall bursts, and recording the pressure value of the sealing failure.

6. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 2, characterized in that, The test conditions for the isothermal pressure cyclic test are set as follows: the primary side test temperature is the primary side design temperature, and the cyclic test pressure range is the sum of the primary side design pressure and the maximum pressure difference between the primary and secondary sides; the secondary side test temperature is the secondary side design temperature, and the cyclic test pressure range is the sum of the saturated water pressure at the secondary side design temperature and the maximum pressure difference between the secondary and primary sides; the number of cycles is the number of transients that can encompass the design transients exceeding the set pressure fluctuation range. For the plug test piece, the principle of first testing and then testing twice was followed, and constant temperature and pressure cycling tests were carried out according to the test conditions.

7. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 2, characterized in that, The test conditions for the temperature and pressure dual-cycle test are set as follows: the medium is boron-lithium water, the water chemical parameters are adjusted to be consistent with the primary side water chemical parameters of the steam generator design conditions, the temperature is heated to the primary side design temperature at a temperature gradient of 58-120℃ / h, the pressure is increased from atmospheric pressure to the primary side design pressure as the temperature rises, the temperature is held at the highest temperature for 3 hours and the highest pressure is maintained, the temperature is cooled to 50℃ at a cooling rate of more than 58℃ / h, and the pressure is reduced to atmospheric pressure as the temperature drops. During this period, the pressure is always kept higher than the saturated vapor pressure at the corresponding temperature to complete one cycle, and the number of cycles is at least 4. A temperature and pressure dual-cycle test was conducted on the primary side of the plug test piece according to the test conditions.

8. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 2, characterized in that, The test conditions for the constant pressure temperature cycling test are set as follows: the primary side medium is boron-lithium water, the secondary side medium is deionized water, the water chemical parameters are adjusted to be consistent with the primary and secondary side water chemical parameters under the design conditions of the steam generator, the primary side test pressure is taken as the primary side design pressure, the temperature cycling range is from room temperature to the primary side design temperature, the number of cycles takes into account the number of heating and cooling cycles of the power plant, and according to the design transients, the number of combined heating and cooling transients of the power plant across the entire temperature range is included. For the plug test piece, the principle of first testing and then testing twice was followed, and constant pressure and temperature cycling tests were carried out according to the test conditions.

9. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 1, characterized in that, The test conditions for the thermal shock test are set as follows: the temperature change range is from room temperature to the primary side design temperature, the temperature rise range is from room temperature to the primary side design temperature, after removal, the air cooling device is used to cool to 150°C, the spray cooling device is used to cool from 150°C to 80°C, and the spray cooling device is used to cool from 80°C to room temperature, with a cycle of 10 times. The plug test specimens were subjected to thermal shock tests according to the test conditions.

10. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 3, characterized in that, The helium leakage requirement after the hydrostatic test is as follows: the plug test piece is subjected to a hydrostatic test and a helium leak test, and the helium leakage rate after the hydrostatic test must meet the requirement that the helium leakage rate is less than the set value. The maximum allowable movement distance requirement is: the movement distance of the plug test piece must be less than the maximum allowable movement distance requirement.

11. The test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in claim 1, characterized in that, The test conditions for the corrosion test are set as follows: the medium is a degassed NaOH solution with a concentration of 100±3 g / L, the temperature is 350±3℃, the pressure is 152±8 bar (the pressure error depends on the temperature error), and the test time is at least 1000 h. Corrosion tests were conducted on the plug test specimens according to the test conditions; The corrosion test acceptance criteria are set as follows: after the corrosion test is completed, the plug test piece undergoes a hydrostatic test and a helium leak test, which must meet the helium leakage requirement of <10^(-8) Pa·m^3 / s; and the plug test piece is cut along the center line of the end face by wire cutting, and after grinding and polishing, the cross-section of the plug test piece tube is observed, focusing on the stress corrosion morphology on the inner side of the tube cross-section. If no obvious corrosion cracks are observed in the magnified cross-sectional view, it passes; otherwise, it fails.

12. A test apparatus for verifying the performance of mechanical plugs on heat exchanger tubes, characterized in that, The test apparatus is used to perform the test method for verifying the performance of the mechanical plug of the heat exchanger heat transfer tube as described in any one of claims 1-11. The test apparatus includes a water pressure test device, a constant temperature and pressure cycle test device, a temperature and pressure cycle test device, a thermal shock test device, and a corrosion test device. The hydrostatic testing equipment is used to perform hydrostatic pressure tests and overpressure tests. The constant temperature and pressure cycling test equipment is used to conduct constant temperature and pressure cycling tests. The temperature and pressure cycling test equipment is used to perform temperature and pressure dual-cycle tests and constant pressure temperature cycling tests. The thermal shock testing equipment is used to conduct thermal shock tests; The corrosion testing equipment is used to conduct corrosion tests.

13. The test apparatus for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes as described in claim 12, characterized in that, The hydrostatic testing equipment includes a high-pressure water supply circuit and a data acquisition and control system; The high-pressure water supply circuit includes a water supply branch and a return branch. The plug test piece is connected between the water supply branch and the return branch. The water supply branch includes a water tank, a low-pressure booster pump, a high-pressure booster pump, and a pressure sensor, which are connected in sequence along the water flow direction. The return branch includes an electromagnetic pressure relief valve. The high-pressure booster pump is driven by air pressure, and its drive pipeline is equipped with a compressed air source and a solenoid valve. The data acquisition and control system is electrically or communicatively connected to the solenoid valve, the solenoid pressure relief valve, and the pressure sensor.

14. The test apparatus for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes as described in claim 12, characterized in that, The isothermal pressure cycling test equipment includes a pressure regulating circuit, a high-temperature reactor, a data acquisition and control system, and a pressure monitoring module. The pressure regulating circuit includes a water supply branch and a return branch. The water supply branch includes a water tank, a high-pressure pump, and a solenoid valve connected in sequence along the water flow direction. The return branch includes a solenoid pressure relief valve. The plug test piece is placed in the high-temperature reactor, with one end connected between the water supply branch and the water return branch, and the other end connected to the pressure monitoring module; the high-temperature reactor is equipped with a thermocouple; The data acquisition and control system is electrically or communicatively connected to the thermocouple, the pressure monitoring module, the solenoid valve, and the solenoid pressure relief valve.

15. The test apparatus for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes as described in claim 12, characterized in that, The temperature and pressure cycling test equipment includes a pressure regulating circuit, a water chemistry circuit, a high-temperature and high-pressure autoclave, a cooling system, a data acquisition and control system, and a pressure monitoring module. The pressure regulating circuit includes a water supply branch and a return branch. The water supply branch includes a water tank, a high-pressure pump, and a solenoid valve connected in sequence along the water flow direction. The return branch includes a solenoid pressure relief valve. The water chemistry circuit includes a high-pressure metering pump, a dosing point, a peristaltic pump, a gas source solenoid valve, and a hydrogen source, which are connected sequentially along the water flow direction. The cooling system includes a heat exchanger connected between the water supply branch and the water return branch; The plug test piece is placed in the high-temperature and high-pressure reactor, with one end connected to the heat exchanger and the other end connected to the pressure monitoring module; the high-temperature and high-pressure reactor is equipped with a thermocouple; The data acquisition and control system is electrically or communicatively connected to the thermocouple, the pressure monitoring module, the solenoid valve, the solenoid pressure relief valve, and the gas source solenoid valve.

16. The test apparatus for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes as described in claim 12, characterized in that, The thermal shock testing equipment includes a high-temperature furnace, a cooling system, and a data acquisition and control system. The cooling system includes an air cooling device, a spray cooling device, and a shower cooling device. A thermocouple is installed inside the high-temperature furnace, and a test thermocouple is connected to the plug test piece. The data acquisition and control system is electrically or communicatively connected to the thermocouple and the test thermocouple.

17. The test apparatus for verifying the performance of mechanical plugs on heat exchanger heat transfer tubes as described in claim 12, characterized in that, The corrosion testing equipment includes a reaction vessel and a data acquisition and control system; The data acquisition and control system is electrically or communicatively connected to the reactor.

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