Passive residual heat removal experiment system and method

Abstract

The invention belongs to the technical field of residual heat removal, and discloses a passive residual heat removal experiment system, which comprises a seawater simulation water tank, a system loop pipeline, a valve and a measurement and control system, the seawater simulation water tank is composed of a shell side, a pipe side, a pipe plate and a header. The integrated passive residual heat removal experiment body is arranged, so that a main loop system, a seawater system and a cooling water system are arranged in a centralized manner, and the arrangement of the experiment system is simplified. The seawater system achieves full-power natural circulation, and the real operation environment of the system can be vivid. Temperature measuring points are arranged at the inlet of the main loop system and the inlet of the pipe bundle, so that the temperature nonuniformity of the inlet of the pipe bundle of the passive residual heat removal system can be monitored. Series of temperature measurement are arranged on the shell side of the integrated passive residual heat removal experiment body, so that the flow heat transfer behavior of the seawater system is monitored.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste heat removal, and in particular relates to a passive waste heat removal experimental system and method. Background Art

[0002] The passive waste heat removal experimental system takes the passive waste heat removal system of a certain device as the simulation object. By constructing a passive waste heat removal heat exchanger and a seawater simulation tank, it has the ability to study the operating characteristics of the passive waste heat removal system under conditions of simulating power outages in the entire plant and small-break loss of water accidents.

[0003] Existing technology 1: Active pump driven waste heat removal system Typical form: Most traditional nuclear power plants use electric pumps or mechanical pumps to circulate the cooling medium to remove the remaining heat from the core and achieve cooling through forced flow heat exchange.

[0004] Problems: Dependence on electricity or external power sources, prone to failure in severe accidents or power outages; Heat buildup in the system after a pump failure may cause equipment damage or safety risks; The control is complex, the maintenance cost is high, and it is not representative for experimental simulation of nuclear accident conditions.

[0005] Prior art 2: Natural circulation cooling device without control feedback Typical form: Natural circulation experimental equipment usually relies on height difference to drive fluid circulation, has a simple structure and no dynamic adjustment device.

[0006] Problems: The system lacks pressure regulation and feedback control mechanisms, resulting in poor stability; The simulation environment is single and cannot realize the experimental reproduction of complex thermal processes; The heat exchange structure is unclear, the thermal efficiency is low, and the experimental data is unstable. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a passive residual heat removal experimental system.

[0008] The present invention is implemented in such a way that a passive residual heat removal experimental system comprises: Seawater simulation tank, system loop pipeline, valves, measurement and control system; The seawater simulation tank consists of shell side, tube side, tube sheet and header; The seawater simulation water tank is divided into two parts by the rectangular flow channel in the middle. The inside of the rectangular flow channel is the pipe of the passive waste heat exhaust cooler, and the two sides of the rectangular flow channel are the pipes of the seawater cooler. The expansion tank of the seawater simulation water tank is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the required pressure of the seawater simulation water tank in a steady state can be achieved. The shell side includes a shell, a rectangular flow channel baffle, the heat exchange tubes of the passive residual heat removal cooler, and the heat exchange tubes of the seawater cooler; A connecting pipe is arranged above the seawater cooler, the size of the connecting pipe is Φ21×2mm, the connecting pipe is connected to an expansion tank, and a safety valve and an exhaust pipe are arranged at the top of the expansion tank.

[0009] Furthermore, the inner diameter of the shell is 700mm and the wall thickness is 7mm; the height of the rectangular flow channel baffle is 525mm, and the distance between the two baffles is 72mm.

[0010] Furthermore, the size of the heat exchange tubes of the passive residual heat removal cooler is Φ8×1mm, the length is 2.5m, there are 66 tubes in total, the spacing is 22mm, and they are arranged in a triangular pattern.

[0011] Furthermore, the size of the heat exchange tubes of the seawater cooler is Φ10×1mm, the length is 2.7m, there are 100 tubes on each side of the baffle, 200 tubes in total, the spacing is 20mm, and they are arranged in a square pattern.

[0012] Furthermore, the inlets and outlets of the heat exchange tubes of the passive residual heat removal cooler are connected to a header, the size of the header is Φ89×5mm, and the inlets and outlets of the heat exchange tubes of the seawater cooler are connected to a tube sheet.

[0013] Furthermore, for the actual heat exchange power Q of the seawater simulation water tank, the flow rate of the circulation side can be obtained through the formula qm = Q / c·Δt.

[0014] Another object of the present invention is to provide a method for passive residual heat removal experiment, including: Step 1, the inlets and outlets of the shell side of the main heat exchanger are connected to the high-temperature side loop to provide a heat source for the natural circulation of the seawater simulation water tank. High-temperature water enters the high-temperature side loop from the shell side outlet of the main heat exchanger, is cooled after passing through a regulating valve and then enters the high-temperature water pipe side of the seawater simulation water tank, and then returns to the shell side inlet of the main heat exchanger; Step 2, the original cooling water inlet and outlet pipes are connected to the cooling water loop to provide a cold source for the natural circulation of the seawater simulation water tank; Step 3, on the natural circulation side of the seawater simulation water tank, after being heated by the high-temperature water pipe inside the rectangular flow channel of the seawater simulation water tank, it is then cooled by the cooling water pipe outside the rectangular flow channel, and a natural circulation is formed relying on the temperature difference; Step 4, the expansion tank of the seawater simulation water tank is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the pressure required for the seawater simulation water tank under steady state is achieved, so as to simulate the working scenario of the equipment underwater.

[0015] Another object of the present invention is to provide a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the steps of the passive residual heat removal experiment method.

[0016] Another object of the present invention is to provide a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the passive residual heat removal experiment method.

[0017] Another object of the present invention is to provide an information data processing terminal for implementing the passive residual heat removal experiment system.

[0018] Combined with the above technical solutions and the solved technical problems, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows: The present invention provides an integrated passive residual heat removal experimental body, which realizes the centralized layout of the primary loop system, the seawater system and the cooling water system, and simplifies the layout of the experimental system. The seawater system realizes full-power natural circulation, and can more realistically simulate the actual operating environment of the system. By setting temperature measurement points at the inlet of the primary loop system and the inlet of the tube bundle, the temperature non-uniformity at the inlet of the tube bundle of the passive residual heat removal system can be monitored. By setting a series of temperature measurements on the shell side of the integrated passive residual heat removal experimental body, the flow and heat transfer behavior of the seawater system can be monitored.

[0019] The shell side inlet and outlet of the main heat exchanger of the present invention are connected to the high-temperature side loop, providing a heat source for the natural circulation of the seawater simulation tank. High-temperature water enters the high-temperature side loop from the shell side outlet of the main heat exchanger, is cooled after passing through the regulating valve and enters the high-temperature water pipe side of the seawater simulation tank, and then returns to the shell side inlet of the main heat exchanger; the original cooling water inlet and outlet pipes are connected to the cooling water loop, providing a cold source for the natural circulation of the seawater simulation tank; the natural circulation side of the seawater simulation tank is heated by the high-temperature water pipe inside the rectangular flow channel of the seawater simulation tank and then cooled by the cooling water pipe outside the rectangular flow channel, and a natural circulation is formed depending on the temperature difference. The expansion tank of the seawater simulation tank is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the pressure required by the seawater simulation tank under steady state can be achieved, so as to simulate the working scenario of the equipment underwater.

[0020] The present invention realizes the pressure stabilization regulation and overpressure automatic pressure relief during the system operation process, significantly improves the stability and safety of the system, and is applicable to the experimental simulation under extreme conditions such as power failure.

[0021] The present invention simulates the passive heat exchange process under the condition of cutting off the cold source of a real nuclear power plant: the seawater simulation tank realizes the precise distribution of the heat exchange tubes through the shell-side - tube-side structure and the intermediate rectangular flow channel, simulates the working conditions of a real cooler, and improves the experimental accuracy.

[0022] The composite heat exchange structure of the present invention improves the heat exchange efficiency: the tube arrangement design distinguishes between the passive residual heat discharge pipes and the seawater cooling pipes, realizes the optimization of the heat exchange path, and improves the heat exchange rate and response speed.

[0023] The system of the present invention has a complete closed loop and has the ability of experimental monitoring: the system is provided with a complete loop, a sewage discharge structure, and monitoring sensors, realizes the whole process monitoring and control from the heat source to the cold source, and has good value as a scientific research experimental platform. Brief Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the structure of the passive residual heat discharge experimental system and the integrated passive residual heat discharge experimental body provided by the embodiment of the present invention.

[0025] Figure 2 It is a flow chart of the passive residual heat discharge experimental method provided by the embodiment of the present invention.

[0026] Figure 3 It is a schematic diagram of the seawater circuit provided by the embodiment of the present invention.

[0027] Figure 4 It is a structural diagram of the seawater simulation water tank provided by the embodiment of the present invention.

[0028] In the figure: 1, pressure stabilizer; 2, safety valve; 3, exhaust port; 4, expansion tank; 5, seawater simulation water tank; 6, cooling water outlet pipe; 7, sewage discharge port; 8, pipe to the inlet of the main heat exchanger; 9, main heat exchanger outlet pipe; 10, pipe to the cooling water inlet. Detailed Embodiments

[0029] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] As Figure 1 shown, a passive residual heat discharge experimental system provided by an embodiment of the present invention includes: A pressure stabilizer 1, a safety valve 2, an exhaust port 3, an expansion tank 4, a seawater simulation water tank 5, a cooling water outlet pipe 6, a sewage discharge port 7, a pipe to the inlet of the main heat exchanger 8, a main heat exchanger outlet pipe 9, and a pipe to the cooling water inlet 10.

[0031] A seawater simulation water tank 5, system loop pipes, valves, and a measurement and control system; The seawater simulation water tank 5 is composed of a shell side, a tube side, a tube sheet, and a header; The seawater simulation tank 5 is divided into two parts by a middle rectangular flow channel. Inside the rectangular flow channel are the exhaust pipes of the passive residual heat removal cooler, and on both sides outside the rectangular flow channel are the exhaust pipes of the seawater cooler; The expansion tank 4 of the seawater simulation tank 5 is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the pressure required for the seawater simulation tank under steady state is achieved; The shell side includes a shell, a rectangular flow channel baffle, heat exchange tubes of the passive residual heat removal cooler, and heat exchange tubes of the seawater cooler; A connecting pipe is arranged above the seawater cooler. The size of the connecting pipe is Φ21×2mm. The connecting pipe is connected to the expansion tank, and a safety valve 2 and an exhaust pipe are arranged at the top of the expansion tank.

[0032] In the embodiment of the present invention, the inner diameter of the shell is 700mm and the wall thickness is 7mm; the height of the rectangular flow channel baffle is 525mm, and the distance between the two baffles is 72mm.

[0033] When the system starts to run, the cooling medium enters the passive residual heat removal cooling system through the main heat exchanger outlet pipe 9 via the valve V101. The medium flows through the cooling water inlet pipe 10 and then enters the tube side part of the seawater simulation tank 5, where it exchanges heat with the seawater on the shell side in the exhaust pipes. The cooled medium then flows out through the main heat exchanger inlet pipe 8, and after passing through V102, PD01, and FB01, it returns to the main heat exchange equipment, forming a complete closed cycle. In the initial stage, it is necessary to set appropriate initial liquid level and pressure through the expansion tank 4 to ensure stable circulation conditions.

[0034] The seawater simulation tank 5 divides the shell side into two regions through a middle - set rectangular flow channel. Inside the central rectangular flow channel are arranged the heat exchange exhaust pipes of the passive residual heat removal cooler, and on the outer sides are arranged the heat exchange exhaust pipes of the seawater cooler. The heat exchange medium flows in the exhaust pipes and indirectly exchanges heat with the simulated seawater on the shell side, simulating the residual heat removal scenario after the nuclear power plant loses its active cooling capacity. The two baffles are 525mm high and 72mm apart, forming a stable and controlled flow channel to ensure good heat exchange effect.

[0035] The expansion tank 4 is connected to the seawater simulation tank 5 through a connecting pipe at the top, and is used to dynamically adjust the pressure on the shell side. The Φ21×2mm connecting pipe above it can ensure sufficient flow area, and together with the safety valve 2 and the exhaust port 3 at the top of the tank, it forms a complete pressure regulation and pressure relief loop. When the internal pressure of the system exceeds the set upper limit, the safety valve automatically opens to prevent the system from over - pressurizing; at the same time, the exhaust port can discharge the residual air inside the system during startup to avoid air blockage and improve the heat exchange efficiency.

[0036] To ensure the safety and cleanliness of the long-term operation of the system, a sewage outlet 7 is provided at the bottom of the system, which can discharge the residual liquid or sediment in the system after the experiment to avoid scale accumulation affecting the system efficiency. In addition, the cooling water outlet pipe 6 leads out the heat-exchanged medium from the system and then enters the next treatment link or is reused. Combining the measurement and control system with pressure, flow, and temperature sensors (such as TT, FT, PT series) arranged at multiple points, the real-time monitoring and adjustment of the system operation state are realized to ensure the accuracy of the experimental data and the stability of the system operation.

[0037] The heat exchange tubes of the passive residual heat removal cooler provided in the embodiment of the present invention have a size of Φ8×1mm, a length of 2.5m, a total of 66 tubes, a spacing of 22mm, and are arranged in a triangular pattern.

[0038] The heat exchange tubes of the seawater cooler provided in the embodiment of the present invention have a size of Φ10×1mm, a length of 2.7m, 100 tubes on each side of the baffle, a total of 200 tubes, a spacing of 20mm, and are arranged in a square pattern.

[0039] The inlets and outlets of the heat exchange tubes of the passive residual heat removal cooler provided in the embodiment of the present invention are connected to the header, and the size of the header is Φ89×5mm. The inlets and outlets of the heat exchange tubes of the seawater cooler are connected to the tube sheet.

[0040] For the actual heat exchange power Q of the seawater simulation tank provided in the embodiment of the present invention, the flow rate on the circulation side can be obtained through the formula qm = Q / c·Δt.

[0041] As Figure 2 shown, a passive residual heat removal experiment method provided in the embodiment of the present invention includes: S101, the inlets and outlets on the shell side of the main heat exchanger are connected to the high-temperature side circuit to provide a heat source for the natural circulation of the seawater simulation tank. High-temperature water enters the high-temperature side circuit from the shell side outlet of the main heat exchanger, passes through the regulating valve, and then enters the high-temperature water pipe side of the seawater simulation tank to cool down, and then returns to the shell side inlet of the main heat exchanger; S102, the original cooling water inlet and outlet pipes are connected to the cooling water circuit to provide a cold source for the natural circulation of the seawater simulation tank; S103, the natural circulation side of the seawater simulation tank is heated by the high-temperature water pipe inside the rectangular flow channel of the seawater simulation tank, and then cooled by the cooling water pipe outside the rectangular flow channel, and a natural circulation is formed relying on the temperature difference; S104, the expansion tank of the seawater simulation tank is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the pressure required by the seawater simulation tank under steady state is achieved, so as to simulate the working scenario of the equipment underwater.

[0042] Specific implementation of the present invention: 1.1 Function The passive residual heat removal experimental system is required to achieve natural circulation in the seawater simulation tank under the given heat source and cold source inputs, and measure the natural circulation flow rate, temperature, and pressure parameters. By adjusting the liquid level and pressure of the expansion tank, the scenario of the equipment simulating underwater operation is realized.

[0043] 1.2 Input Parameters of the System and Equipment The passive residual heat removal experimental system mainly includes a seawater simulation tank, a high-temperature side loop, and a cooling water loop. The seawater simulation tank includes the tube side of the passive residual heat removal cooler (high-temperature water side), the shell side of the seawater simulation tank (natural circulation side), and the tube side of the seawater cooler (cooling water side).

[0044] The main design input parameters of the passive residual heat removal experimental system are shown in Table 1.

[0045] Table 1 Main Design Input Parameters of the Test System 1.3 Process Flow The schematic diagram of the passive residual heat removal experimental system is as Figure 1 , Figure 4 shown. The system consists of a seawater simulation tank 5, system loop pipes, valves, and a measurement and control system.

[0046] The part within the dotted box is the passive residual heat removal experimental system. The shell side inlet and outlet of the main heat exchanger are connected to the high-temperature side loop, providing a heat source for the natural circulation of the seawater simulation tank. High-temperature water enters the high-temperature side loop from the shell side outlet of the main heat exchanger, is cooled after passing through the regulating valve and entering the high-temperature water pipe side of the seawater simulation tank, and then returns to the shell side inlet of the main heat exchanger; the original cooling water inlet and outlet pipes are connected to the cooling water loop, providing a cold source for the natural circulation of the seawater simulation tank; the natural circulation side of the seawater simulation tank is heated by the high-temperature water pipe inside the rectangular flow channel of the seawater simulation tank and then cooled by the cooling water pipe outside the rectangular flow channel, forming a natural circulation relying on the temperature difference.

[0047] The expansion tank of the seawater simulation tank is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the required pressure of the seawater simulation tank under steady state is achieved, thereby simulating the working scenario of the equipment underwater.

[0048] The process flow of the passive residual heat removal experimental system is as Figure 1 shown. The system consists of a loop system, an integrated passive residual heat removal experimental body, and an instrument control system.

[0049] The loop system includes a main loop system, a seawater system, and a cooling water system. The main loop system is a high-temperature and high-pressure loop system, which includes a main loop inlet pipeline, an inlet ball valve V101, an outlet ball valve V102, and a main loop outlet pipeline. The seawater system is a natural circulation system, which is located on the shell side of the integrated passive heat removal test facility and is provided with an expansion tank to compensate for the seawater expansion caused by the temperature rise. The cooling water system is a normal-temperature and normal-pressure system, which mainly includes a cooling water inlet pipeline and a cooling water outlet pipeline 6.

[0050] The integrated passive residual heat removal test facility is the core equipment, which includes the main loop system side, the seawater loop, and the cooling water side.

[0051] The instrument control system includes a main loop inlet temperature measuring point TT01, an outlet temperature measuring point TT022, a tube bundle inlet temperature measuring points TT02 and TT03, a flowmeter FE01, a pressure measuring point PT01, a seawater loop expansion tank liquid level LT01, a cooling water loop inlet temperature measuring point TT21, and an outlet temperature measuring point TT022. In order to better measure the flow and heat transfer on the seawater side, 4 groups of temperature measuring points are arranged on the integrated passive residual heat removal test facility. The first group is TT04, TT05, TT06, and TT07, the second group is TT08, TT09, TT10, and TT11, the third group is TT12, TT13, TT14, and TT15, and the fourth group is TT16, TT17, TT18, and TT119. The 4 groups of temperature measuring points are evenly arranged along the shell side of the integrated passive residual heat removal test facility.

[0052] When the passive residual heat removal test system is put into operation, the high-temperature fluid in the main loop system enters the globe valve V101 through the main loop outlet pipeline, and then enters the integrated passive residual heat removal test facility. After being cooled by the seawater system on the shell side, it enters the main loop inlet pipeline through V102. The fluid of the cooling water system flows in from the cooling water inlet pipeline, enters the integrated passive residual heat removal test facility to cool the seawater system, and then flows out from the cooling water outlet pipeline.

[0053] The seawater system is located on the shell side of the integrated passive residual heat removal test facility, as shown in Figure 3 .. In the middle rectangular channel of the integrated passive residual heat removal test facility is the main loop high-temperature tube bundle, and inside it is the main loop high-temperature fluid; on both sides of the upper part are the cooling water pipes. After being heated by the high-temperature tubes, the density of the seawater becomes smaller, and it rises along the rectangular channel and flows. After being deflected, it is cooled by the cooling water tube bundle, the density becomes larger, and it flows towards the inlet of the rectangular channel.

[0054] The flow rate of the seawater system is calculated by using the temperature difference Δt between the average temperatures at the inlet and outlet of the rectangular flow channel. Measuring the flow rate and the temperature difference between the inlet and outlet on the high-temperature side can obtain the actual heat transfer power Q of the seawater simulation water tank. Through the formula qm = Q / c·Δt, the flow rate on the circulation side can be obtained.

[0055] 1.4 Seawater simulation tank The seawater simulation tank consists of a shell side, a tube side, tube sheets and headers, as shown in Figure 3 below. The passive residual heat removal cooler is placed horizontally and slopes downward.

[0056] The seawater simulation tank is divided into two parts by a middle rectangular flow channel. The tubes of the passive residual heat removal cooler are inside the rectangular flow channel, and the tubes of the seawater cooler are on both sides outside the rectangular flow channel. The shell side includes a shell, rectangular flow channel baffles, heat exchange tubes of the passive residual heat removal cooler and heat exchange tubes of the seawater cooler. The inner diameter of the shell is 700 mm and the wall thickness is 7 mm; the height of the rectangular flow channel baffle is 525 mm, and the distance between the two baffles is 72 mm; the size of the heat exchange tubes of the passive residual heat removal cooler is Φ8×1 mm, the length is 2.5 m, there are 66 tubes in total, the spacing is 22 mm, and they are arranged in a triangular pattern; the size of the heat exchange tubes of the seawater cooler is Φ10×1 mm, the length is 2.7 m, there are 100 tubes on each side of the baffle, 200 tubes in total, the spacing is 20 mm, and they are arranged in a square pattern. The inlets and outlets of the heat exchange tubes of the passive residual heat removal cooler are connected to the headers, and the size of the headers is Φ89×5 mm. The inlets and outlets of the heat exchange tubes of the seawater cooler are connected to the tube sheets.

[0057] The flow rate on the circulation side is calculated using the temperature difference Δt between the average temperatures at the inlet and outlet of the rectangular flow channel. Measuring the flow rate and the temperature difference at the inlet and outlet on the high-temperature side can obtain the actual heat exchange power Q of the seawater simulation tank. Through the formula qm = Q / c·Δt, the flow rate on the circulation side can be obtained.

[0058] Considering the need for relevant research on the influence of local boiling on the circulation side, 4 groups (8 in total) of circular visual windows with a diameter of 100 mm are set on the shell side cylinder of the passive residual heat removal cooler. The visual windows are set above and below the rectangular flow channel and arranged along the axial direction of the cylinder.

[0059] Integrated passive residual heat removal experimental body The integrated passive residual heat removal experimental body consists of a shell side, a tube side, tube sheets and headers, as shown Figure 1 below. The integrated passive residual heat removal experimental body is placed horizontally and slopes downward.

[0060] The integrated passive residual heat removal experimental body is divided into two parts by a middle rectangular flow channel. Inside the rectangular flow channel are the high-temperature main loop tube bundles, and on both sides outside the rectangular flow channel are the cooling water tube bundles. The shell side includes the shell, rectangular flow channel baffle plates, high-temperature main loop tube bundles, and cooling water tube bundles. The inner diameter of the shell is 700 mm, and the wall thickness is 7 mm; the height of the rectangular flow channel baffle plates is 525 mm, and the distance between the two baffle plates is 72 mm; the heat exchange tube size of the integrated passive residual heat removal experimental body is Φ8×1 mm, the length is 2.5 m, there are 66 tubes in total, the spacing is 22 mm, and they are arranged in a triangular pattern; the heat exchange tube size of the seawater cooler is Φ10×1 mm, the length is 2.7 m, there are 100 tubes on each side of the baffle plates, 200 tubes in total, the spacing is 20 mm, and they are arranged in a square pattern. The high-temperature main loop tube bundles are connected to the header, the size of the header is Φ89×5 mm, and the inlet and outlet of the cooling water tube bundles are connected to the tube sheet.

[0061] Considering the need for local boiling research on the shell side, 4 groups (8 in total) of circular visual windows with a diameter of 100 mm are set on the shell side cylinder of the passive residual heat removal cooler. The visual windows are set above and below the rectangular flow channel and arranged along the axial direction of the cylinder.

[0062] 1.5 Expansion tank The seawater simulation water tank requires a certain gas space, and the temperature change during operation will cause the liquid level to change. An expansion tank is needed to discharge the excess water. A connecting pipe with a size of Φ21×2 mm is set above the seawater cooler, and the connecting pipe is connected to the expansion tank. A safety valve 2 and an exhaust pipe are set at the top of the expansion tank.

[0063] To make the expansion tank meet the usage requirements, the relationship between the water volume and pressure of the expansion tank is calculated. In the calculation, the initial pressure of the expansion tank is 0.6 MPa, the filling rate is 10%, the temperature is 40 °C, after heating, the temperature is 60 °C, the pressure is 1.2 MPa, and the filling rate is 55%.

[0064] The expansion tank of the integrated passive residual heat removal experimental body is used to regulate the pressure. By setting different initial pressures and initial liquid levels, the required pressure of the seawater simulation water tank under steady state is achieved, so as to simulate the working scenario of the equipment underwater. A connecting pipe with a size of Φ21×2 mm is set above the shell side of the integrated passive residual heat removal experimental body, and the connecting pipe is connected to the expansion tank. A safety valve 2 and an exhaust pipe are set at the top of the expansion tank.

[0065] To make the expansion tank meet the usage requirements, the relationship between the water volume and pressure of the expansion tank is calculated. In the calculation, the initial pressure of the expansion tank is 0.6 MPa, the filling rate is 10%, the temperature is 40 °C, after heating, the temperature is 60 °C, the pressure is 1.2 MPa, and the filling rate is 55%.

[0066] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A passive residual heat removal experimental system, characterized in that, The passive residual heat removal experimental system includes: A seawater simulation water tank, a system loop pipeline, valves, and a measurement and control system; The seawater simulation water tank consists of a shell side, a tube side, tube sheets, and headers; The seawater simulation water tank is divided into two parts by a middle rectangular flow channel. The tubes of the passive residual heat removal cooler are inside the rectangular flow channel, and the tubes of the seawater cooler are on both sides outside the rectangular flow channel; The expansion tank of the seawater simulation water tank is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the required pressure of the seawater simulation water tank under steady state is achieved; The shell side includes a shell, a rectangular flow channel baffle, heat exchange tubes of the passive residual heat removal cooler, and heat exchange tubes of the seawater cooler; A connecting pipe is arranged above the seawater cooler and is connected to the expansion tank. A safety valve and an exhaust pipeline are arranged at the top of the expansion tank.

2. The passive residual heat removal experimental system according to claim 1, wherein The inner diameter of the shell is 700 mm, and the wall thickness is 7 mm; the height of the rectangular flow channel baffle is 525 mm, and the distance between the two baffles is 72 mm.

3. The passive residual heat removal experimental system according to claim 1, wherein The size of the heat exchange tubes of the passive residual heat removal cooler is Φ8×1 mm, the length is 2.5 m, there are 66 tubes in total, the spacing is 22 mm, and they are arranged in a triangular pattern.

4. The passive residual heat removal experimental system according to claim 1, wherein The size of the heat exchange tubes of the seawater cooler is Φ10×1 mm, the length is 2.7 m, there are 100 tubes on each side of the baffle, 200 tubes in total, the spacing is 20 mm, and they are arranged in a square pattern.

5. The passive residual heat removal experimental system according to claim 1, wherein, The inlets and outlets of the heat exchange tubes of the passive residual heat removal cooler are connected to the header. The size of the header is Φ89×5 mm, and the inlets and outlets of the heat exchange tubes of the seawater cooler are connected to the tube sheets.

6. The passive residual heat removal experimental system according to claim 1, wherein For the actual heat exchange power Q of the seawater simulation water tank, the flow rate on the circulation side can be obtained through the formula qm = Q / c·Δt.

7. A passive residual heat removal experimental method for implementing the passive residual heat removal experimental system according to any one of claims 1-6, characterized in that, The passive residual heat removal experimental method includes: Step 1: The inlets and outlets of the shell side of the main heat exchanger are connected to the high-temperature side loop to provide a heat source for the natural circulation of the seawater simulation water tank. High-temperature water enters the high-temperature side loop from the outlet of the shell side of the main heat exchanger, is cooled after passing through the regulating valve and then enters the high-temperature water tube side of the seawater simulation water tank, and then returns to the inlet of the shell side of the main heat exchanger; Step 2: The original cooling water inlet and outlet pipelines are connected to the cooling water loop to provide a cold source for the natural circulation of the seawater simulation water tank; Step 3: The natural circulation side of the seawater simulation water tank is heated by the high-temperature water tube inside the rectangular flow channel of the seawater simulation water tank and then cooled by the cooling water tubes outside the rectangular flow channel, and a natural circulation is formed relying on the temperature difference; Step 4: The expansion tank of the seawater simulation water tank is used to adjust the pressure. By setting different initial pressures and initial liquid levels, the required pressure of the seawater simulation water tank under steady state is achieved, so as to simulate the working scenario of the equipment underwater.

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