System and method for testing thermal cycle characteristics of multi-direction horizontal pipeline of nuclear power station

Abstract

The invention discloses a system and a method for testing thermal cycle characteristics of multidirectional horizontal pipelines of a nuclear power plant, the system comprises a circulating water path and a pressure stabilizing water path, the circulating water path comprises the multidirectional horizontal pipelines (1a, 1b), paired pressure signal detectors (17a, 17b), pipeline heaters (14a, 14b, 14c) and a pipeline heat exchanger (3), and the pressure stabilizing water path comprises a cooling water supply system (18) and a pressure stabilizer (23); the circulating water path is communicated with the pressure stabilizing water path, and the number of the multi-direction horizontal pipelines (1a and 1b) is more than two. The thermal cycle characteristics of the upstream horizontal pipeline, the lateral horizontal pipeline and the downstream horizontal pipeline connected with the main pipeline under the conditions of different temperatures, pressures and volume flows can be researched more effectively, conveniently and accurately, and data support and reference are provided for design optimization of the multi-direction horizontal pipeline of the nuclear power station.

Description

Technical Field

[0001] The invention relates to the field of nuclear power plant pipeline design research, and in particular to a testing system and method for thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant. Background Art

[0002] The structural integrity of the pipelines in nuclear power plants is of great significance to the stable operation of nuclear power plants. As an important component connecting various systems and equipment, if the pipelines fail to rupture, LOCA accidents of varying degrees will be caused. During the operation of nuclear power plants, the transient conditions of the working fluid flow in the pipelines are relatively complex. At present, there have been many nuclear power plant shutdowns caused by pipeline cracks or ruptures at home and abroad. The possibility of thermal cycle phenomena in multi-directional horizontal pipelines in nuclear power plants and the causes of this phenomenon need to be paid special attention to, and test research on the causes, locations, duration and other characteristics of thermal cycles should be carried out. At present, there is no research on the thermal cycle characteristics of multi-directional horizontal pipelines in nuclear power plants under different temperature, pressure and volume flow conditions in the industry, nor is there a test scheme that uses the main pipeline to connect with the downward horizontal branch pipe, the side horizontal branch pipe and the upward horizontal branch pipe at the same time.

[0003] The existing patent CN209513684U discloses a variable tube bundle arrangement heat exchange experimental device, including a natural circulation unit, a forced circulation unit, a convection heat exchange cooling unit and a tube bundle arrangement heating platform, which are connected in series through pipelines to form a circulation loop. The pipeline is provided with a plurality of pressure gauges, temperature sensors and electromagnetic flowmeters for collecting pressure, temperature and flow. Bypass pipelines are respectively arranged in parallel at both ends of the natural circulation unit and the forced circulation unit. The tube bundle arrangement heating platform includes a tube bundle arrangement bracket, a heating power supply arranged at the bottom of the tube bundle arrangement bracket and a transparent heating experimental section at the top. This device can study the heat transfer flow mechanism of different tube bundle arrangements, as well as the boiling heat transfer mechanism and local heat transfer characteristics of the heating section under two circulation conditions. It is helpful for the understanding and in-depth study of the heat transfer mechanism. In addition, the data of the entire system is detected in real time to ensure the data recording of the entire process of the experimental data, and the problem of studying the thermal cycle characteristics of multi-directional horizontal pipelines under different temperature, pressure and volume flow conditions is not solved.

[0004] The existing patent CN115615690A discloses a dynamic and static water test device and test method for high-temperature and high-pressure equipment, including a test piece, a natural circulation loop and a valve body assembly; the input and output ends of the natural circulation loop are connected to the input and output ends of the test piece through the valve body assembly; the natural circulation loop includes a first pipeline connected to the test piece, a heating pipeline connected to the first pipeline, and a cooling pipeline connected to the first pipeline; the second pipeline is connected to the heating pipeline and the cooling pipeline; by setting multiple natural circulation loops and multiple groups of test pieces, and controlling the connection relationship between the natural circulation loop and the test piece through the valve body assembly, a cold and hot shock test is realized through mutually isolated natural circulation loops, and multiple groups of test pieces are cycled by adjusting the on and off of the natural circulation loop. In addition, the pressure head generated by the heating pipeline and the cooling pipeline in the natural circulation loop is used to realize natural circulation, but the problem of studying the thermal cycle characteristics of multi-directional horizontal pipelines under different temperature, pressure, and volume flow conditions is not solved. In summary, the above two existing patents do not solve the problems in the prior art. Summary of the invention

[0005] Based on the above technical problems, the present invention proposes a testing system and method for the thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant to solve the problem of studying the thermal cycle characteristics of multi-directional horizontal pipelines under different temperature, pressure and volume flow conditions.

[0006] To achieve the above-mentioned purpose, the present invention provides a testing system for thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant.

[0007] A test system for thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant, comprising:

[0008] It includes a circulating water circuit and a pressure-stabilizing water circuit, wherein the circulating water circuit includes multi-directional horizontal pipes, paired pressure signal detectors, pipe heaters and pipe heat exchangers, and the pressure-stabilizing water circuit includes a cooling water supply system and a pressure stabilizer;

[0009] The circulating water circuit is connected to the pressure-stabilizing water circuit, and the multi-directional horizontal pipes have more than two. The two or more multi-directional horizontal pipes are arranged in parallel in the circulating water circuit, and an electric switch valve is respectively arranged upstream of each multi-directional horizontal pipe;

[0010] The pipeline heat exchanger, the pipeline heater and the multi-directional horizontal pipeline are sequentially connected in series in the water flow direction of the circulating water circuit, and the paired pressure signal detectors have more than two, and the two or more paired pressure signal detectors are respectively placed between the multi-directional horizontal pipeline and the pipeline heater for measuring the pipeline volume flow rate;

[0011] The internal cooling water of the pressurizer of the pressure-stabilizing water circuit is injected by the cooling water supply system.

[0012] Furthermore, the multi-directional horizontal pipeline includes a main pipeline and branch pipelines, and the branch pipelines are vertically connected to the main pipeline at radial positions of 0°, 180°, 90° or 270° respectively.

[0013] Furthermore, the branch pipeline includes an upward branch pipeline, a downward branch pipeline and a side branch pipeline, the upward branch pipeline is connected to the radial 0° position of the main pipeline, the downward branch pipeline is connected to the radial 180° position of the main pipeline, and the side branch pipeline is connected to the radial 90° or 270° position of the main pipeline.

[0014] Furthermore, the branch pipeline includes a vertical pipeline and a parallel pipeline. The vertical pipeline is vertically connected to the outer surface of the main pipeline through one end, and the parallel pipeline is parallel to the main pipeline and connected to the other end of the vertical pipeline.

[0015] Furthermore, the branch pipeline also includes a blind plate, and the blind plate is arranged at the end of the branch pipeline.

[0016] Furthermore, the blind plate comprises two groups of cooling pipes, the inlets of the two groups of cooling pipes are connected to the radial 0° position of the blind plate, and the outlets of the two groups of cooling pipes are respectively connected to the 90° and 270° positions in the circumferential direction of the blind plate.

[0017] Furthermore, the branch pipe also includes an electric heating wire and a flange. The electric heating wire is spirally arranged on the outside of the branch pipe, and the flange is arranged at the connection between the branch pipe and the main pipe to achieve rotation at different angles.

[0018] Furthermore, in the paired pressure signal detectors, two signal detectors in each paired pressure signal detector are arranged at a fixed distance range of 100 mm-300 mm in the horizontal direction.

[0019] Furthermore, the circulating water circuit includes pipeline spoilers, and the pipeline spoilers are respectively arranged between the multi-directional horizontal pipelines and the pipeline heaters.

[0020] Furthermore, the pipeline heater also includes at least three pipeline heaters, the pipeline heaters have at least three different heating powers, and the pipeline heaters are arranged in parallel in the circulating water circuit.

[0021] Furthermore, the circulating water circuit includes a multi-stage filter and a circulating pump, and the multi-stage filter and the circulating pump are arranged in series between the pipeline heat exchanger and the pipeline heater; the multi-stage filter is arranged at the water inlet of the circulating pump.

[0022] Furthermore, the circulating water circuit also includes a circulating cooling water system, and the circulating cooling water system is connected to the shell side of the pipeline heat exchanger.

[0023] Furthermore, the pressure-stabilizing water circuit includes a pressure relief tank, and the pressure relief tank is connected to the top of the pressure stabilizer through an electric switch valve.

[0024] Furthermore, the pressure-stabilizing water circuit includes a nitrogen supply system, and the nitrogen supply system is connected to the pressure stabilizer through an electric switching valve.

[0025] Furthermore, the voltage stabilizer comprises an electric heating rod, and the electric heating rod is arranged in a vertical arrangement on the lower head of the voltage stabilizer.

[0026] To achieve the above object, the present invention also proposes a method for testing the thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant.

[0027] A method for testing thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant using the above test system comprises:

[0028] S1: adjusting the pressure stabilizing water circuit and the circulating water circuit so that the ambient temperature and ambient pressure in the pressurizer are maintained at target values ​​and are stable;

[0029] S2: heating the cooling water to a target value according to the pipeline heater, measuring the system volume flow according to the paired pressure signal detector, and adjusting the system volume flow to reach the target value;

[0030] Close the electric switch valve upstream of at least one branch where the multi-directional horizontal pipe is located, so that the cooling water flows into at least one other multi-directional horizontal pipe for testing;

[0031] Open the electric switch valve upstream of at least one branch where the multi-directional horizontal pipeline is located that is in a closed state, and close the electric switch valve upstream of at least one other branch where the multi-directional horizontal pipeline is located that is in an open state to conduct a test.

[0032] Furthermore, the step S2 further includes:

[0033] After the cooling water enters the multi-directional horizontal pipeline, it flows into the downward branch pipeline, the side branch pipeline and the upward branch pipeline in the multi-directional horizontal pipeline in sequence;

[0034] After the cooling water enters the multi-directional horizontal pipeline, it flows into the downward branch pipeline, the side branch pipeline and the upward branch pipeline in the multi-directional horizontal pipeline in sequence.

[0035] Furthermore, the step S2 further includes:

[0036] Turn on the electric heating wire outside the branch pipe, and adjust the temperature of the outer wall and blind plate of the branch pipe to the target value and stabilize it.

[0037] Furthermore, the step S2 further includes:

[0038] The circulating cooling water system is turned on, and the cooling water on the shell side of the pipe heat exchanger is continuously circulated at a small volume flow rate.

[0039] Furthermore, the step S1 further includes:

[0040] Open the electric switch valve of the pressure-stabilizing water circuit, start the cooling water supply system, inject cooling water into the cooling water tank, and after the cooling water in the cooling water tank reaches the target liquid level and stabilizes, close the cooling water supply system, open the electric switch valve and the electric regulating valve, and inject the cooling water in the cooling water tank into the circulating water circuit and the pressure stabilizer under the action of gravity;

[0041] Close the electric switch valve, turn on the electric heating rod of the voltage regulator, wait until the ambient pressure reaches the set value, open the electric switch valve, and discharge the water vapor in the voltage regulator into the pressure relief tank. Adjust the heating power of the electric heating rod of the voltage regulator to keep the ambient temperature and pressure in the voltage regulator at the target value and stable.

[0042] Based on the above technical solution, the present invention has at least the following beneficial effects:

[0043] 1. The present invention proposes a test system for the thermal cycle characteristics of multi-directional horizontal pipelines. Through the design of multi-directional pipelines and stabilizers, the system can simulate the thermal cycle characteristics of multi-directional horizontal pipelines under different temperature, pressure, and volume flow conditions, providing comprehensive test data for the design and optimization of nuclear power plant pipelines. The present invention designs thermal cycle tests for downward horizontal pipelines, side horizontal pipelines, and upward horizontal pipelines, thereby covering various thermodynamic conditions that the pipelines may encounter, helping to deeply understand the key characteristics of the thermal cycle phenomenon, such as the cause, location, and duration, and providing an important scientific basis for the safe operation and design optimization of nuclear power plant pipeline systems.

[0044] 2. By adopting high-precision measurement technologies such as paired pressure signal detectors, the system can reduce the reliance on traditional long straight pipe sections without sacrificing measurement accuracy, thereby saving space and material costs. In addition, the compact design of the system reduces the workload of installation and maintenance, further improving the efficiency and economy of the test.

[0045] 3. The present invention proposes a test system for the thermal cycle characteristics of multi-directional horizontal pipes. Since the temperature and pressure increase process of the system is relatively long, the replacement of the multi-directional horizontal pipes must be carried out under normal temperature and pressure conditions, which saves the number of times the multi-directional horizontal pipes are replaced, thereby saving test time and improving the test efficiency of the system. The parallel arrangement of the pipe heaters and the free adjustment of the heating power enable the system to accurately simulate different thermal cycle conditions. At the same time, the system's intelligent control components such as the electric switch valve and the electric regulating valve improve the convenience of operation, make system maintenance and adjustment easier, and reduce maintenance costs and time.

[0046] 4. In the multi-directional horizontal pipeline thermal cycle characteristics test system proposed by the present invention, the pressure stabilizer and pressure relief box design can effectively control and manage pressure fluctuations, further enhancing the safety of the system. In addition, the use of U-shaped communication vessel structure and multi-stage filter ensures the stable operation of the system under high pressure and high temperature conditions, preventing possible equipment damage and accidental interruption of testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0048] Figure 1 A structural diagram of a testing system for thermal cycle characteristics of multi-directional horizontal pipes according to an embodiment is shown;

[0049] Figure 2 A three-dimensional structure diagram of multi-directional horizontal pipelines in one embodiment is shown;

[0050] Figure 3 A schematic diagram of a branch pipeline blind pipe structure according to an embodiment is shown;

[0051] 1a, multi-directional horizontal pipeline; 1b, multi-directional horizontal pipeline; 2, electric switch valve; 3, pipeline heat exchanger; 4, circulating cooling water system; 5, check valve; 6, electric switch valve; 7, multi-stage filter; 8, circulating pump; 9, check valve; 10, electric regulating valve; 11, electric regulating valve; 12, electric regulating valve; 13a, electric switch valve; 13b, electric switch valve; 13c, electric switch valve; 14a, pipeline heater; 14b, pipeline heater; 14c, pipeline heater; 15 a, electric switch valve; 15b, electric switch valve; 16a, pipeline spoiler; 16b, pipeline spoiler; 17a, paired pressure signal detector; 17b, paired pressure signal detector; 18, cooling water supply system; 19, electric switch valve; 20, cooling water tank; 21, electric switch valve; 22, electric switch valve; 23, voltage regulator; 24, electric switch valve; 25, pressure relief tank; 26, electric switch valve; 27, electric switch valve; 28, electric switch valve; 29, nitrogen supply system;

[0052] H1, branch pipeline parallel pipeline; H2, branch pipeline parallel pipeline; H3, branch pipeline parallel pipeline; H4, branch pipeline parallel pipeline; H5, branch pipeline parallel pipeline; H6, branch pipeline parallel pipeline; V1, branch pipeline vertical pipeline; V2, branch pipeline vertical pipeline; V3, branch pipeline vertical pipeline; V4, branch pipeline vertical pipeline; V5, branch pipeline vertical pipeline; V6, branch pipeline vertical pipeline;

[0053] I1, cooling pipe inlet; I2, cooling pipe inlet; I3, cooling pipe inlet; I4, cooling pipe inlet; O1, cooling pipe outlet; O2, cooling pipe outlet; O3, cooling pipe outlet; O4, cooling pipe outlet. DETAILED DESCRIPTION

[0054] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0055] The present invention is further described in detail below in conjunction with specific embodiments, and these embodiments cannot be understood as limiting the scope of protection claimed by the present invention. The term "including" when used indicates the existence of a feature, but does not exclude the existence or addition of one or more other features; the orientation or position relationship indicated by the terms "lateral", "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0056] In the description, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0057] Example

[0058] The present invention proposes a test system for thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant, such as Figure 1 The circuit shown includes a circulating water circuit and a pressure stabilizing water circuit, wherein the circulating water circuit includes multi-directional horizontal pipes 1a, 1b, paired pressure signal detectors 17a, 17b, pipe heaters 14a, 14b, 14c and a pipe heat exchanger 3, and the pressure stabilizing water circuit includes a cooling water supply system 18 and a pressure stabilizer 23;

[0059] The circulating water circuit is connected to the pressure-stabilizing water circuit, and the multi-directional horizontal pipes 1a and 1b have more than two. The more than two multi-directional horizontal pipes 1a and 1b are arranged in parallel in the circulating water circuit, and electric switch valves 15a and 15b are respectively arranged upstream of each multi-directional horizontal pipe 1a and 1b;

[0060] The pipe heat exchanger 3, the pipe heaters 14a, 14b, 14c and the multi-directional horizontal pipes 1a, 1b are connected in series in the direction of water flow in the circulating water circuit. There are more than two paired pressure signal detectors 17a, 17b, and the more than two paired pressure signal detectors 17a, 17b are respectively placed between the multi-directional horizontal pipes 1a, 1b and the pipe heaters 14a, 14b, 14c, and are used to measure the pipe volume flow rate;

[0061] The cooling water inside the pressure stabilizer 23 of the pressure stabilizing water circuit is injected by the cooling water supply system 18 .

[0062] Furthermore, the main pipe and the branch pipe have different sizes, e.g. Figure 2 As shown, the downstream branch pipeline includes V1H1 and V4H4, the lateral branch pipeline includes V2H2 and V5H5, and the upstream branch pipeline includes V3H3 and V6H6, wherein V1, V2, V3, V4, V5 and V6 are vertical pipelines, and H1, H2, H3, H4, H5 and H6 are parallel pipelines.

[0063] Preferably, the material of the multi-directional horizontal pipes 1a and 1b is stainless steel, the design pressure is not less than 17.3 MPa, and the design temperature is not less than 343.3 degrees Celsius.

[0064] Furthermore, the upstream branch pipes V3H3 and V6H6 are connected at the radial position of 0°, which is the direction perpendicular to the ground surface and vertically upward within the main pipe section, and the tolerance can be within plus or minus 5°. The downstream main pipes V1H1 and V4H4 are connected at the position of 180° rotated clockwise in the main pipe section with the above-mentioned radial position of 0° as the starting point, and the tolerance can be within plus or minus 5°. The side branch pipes V2H2 and V5H6 are connected at the position of 90° or 270° rotated clockwise in the main pipe section with the above-mentioned radial position of 0° as the starting point, and the tolerance can be within plus or minus 5°.

[0065] Furthermore, the pipe spoilers 16a and 16b are arranged upstream of the paired pressure signal detectors 17a and 17b, and the pipe spoilers 16a and 16b are provided with gradually converging and expanding nozzles that can change the inner diameter of the pipe. The nozzles are provided with metal protrusions of different numbers and shapes, which are used to interfere with the flow of cooling water in the main pipe, generate pressure fluctuations, and enable the paired pressure signal detectors 17a and 17b to calculate the volume flow rate.

[0066] In this embodiment, the paired pressure signal detectors 17a and 17b detect pressure signals successively, and the pressure signals are processed by the signal processing system to obtain two similar waveforms. After comparison, the time of occurrence of the two identical points is t1 and t2 respectively. The diameter of the main pipeline is D, which can be obtained by the formula Q = πD 2 L / 4(t2-t1) calculates the volume flow of cooling water in the main pipeline in real time and accurately.

[0067] Preferably, the maximum heating power of the pipe heaters 14a, 14b, 14c can be set to 400KW, 600KW and 800KW respectively, and each pipe heater can freely adjust the heating power within the range of 0%-100% to achieve more precise and flexible heating and temperature control of cooling water.

[0068] Furthermore, if Figure 3 The inlets of the internal cooling pipes I1, I2, I3, and I4 of the blind plate are respectively arranged at the above-mentioned radial 0° plus or minus 5° positions, the outlets O1 and O2 of the cooling pipes I1 and I2 are arranged at the radial 90° position, and the outlets O3 and O4 of the cooling pipes I3 and I4 are arranged at the radial 270° position, and each cooling pipe is arranged in an S-shaped alternating manner inside the blind plate to cover the entire blind plate.

[0069] Furthermore, if Figure 1The nitrogen supply system 19 and the pressure relief tank 25 are respectively connected to the top of the pressure stabilizer 23. The pressure relief tank 25 is provided with a differential pressure level gauge. When the cooling water level in the pressure relief tank 25 reaches a set value, the electric switch valve can automatically open to discharge the cooling water from the pressure relief tank 25.

[0070] To achieve the above object, the present invention also proposes a method for testing the thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant using the above test system, comprising:

[0071] S1: Adjusting the pressure stabilizing water circuit and the circulating water circuit so that the ambient temperature and ambient pressure in the pressure stabilizer 23 are maintained at target values ​​and are stable;

[0072] S2: heating the cooling water to a target value according to the pipeline heaters 14a, 14b, 14c, measuring the system volume flow according to the paired pressure signal detectors 17a, 17b, and adjusting the system volume flow to reach the target value;

[0073] Close the electric switch valve 15b upstream of at least one branch where the multi-directional horizontal pipe 1b is located, so that the cooling water flows into at least one other multi-directional horizontal pipe 1a for testing;

[0074] Open the electric switch valve 15b upstream of the branch where at least one of the multi-directional horizontal pipelines 1b is located and is in a closed state, and close the electric switch valve 15a upstream of the branch where at least one of the other multi-directional horizontal pipelines 1a is located and is in an open state, and conduct testing.

[0075] Furthermore, the step S2 further includes:

[0076] After the cooling water enters the multi-directional horizontal pipe 1a, it flows into the downward branch pipe, the side branch pipe and the upward branch pipe in the multi-directional horizontal pipe 1a in sequence;

[0077] After the cooling water enters the multi-directional horizontal pipe 1b, it flows into the downward branch pipe, the side branch pipe and the upward branch pipe in the multi-directional horizontal pipe 1b in sequence.

[0078] Furthermore, the step S2 further includes:

[0079] Turn on the electric heating wire outside the branch pipe, and adjust the temperature of the outer wall and blind plate of the branch pipe to the target value and stabilize it.

[0080] Furthermore, the step S2 further includes:

[0081] The circulating cooling water system 4 is turned on, and the cooling water on the shell side of the pipe heat exchanger 3 is continuously circulated at a small volume flow rate.

[0082] Furthermore, the step S1 further includes:

[0083] Open the electric switch valve 19 of the pressure-stabilizing water circuit, start the cooling water supply system 18, and inject cooling water into the cooling water tank 20. After the cooling water in the cooling water tank 20 reaches the target liquid level and stabilizes, close the cooling water supply system 18, open the electric switch valves 2, 6, 12, 13a, 13b, 13c, 15a, 15b, 21, 24, 26, 27 and the electric regulating valves 10 and 11, and the cooling water in the cooling water tank 20 is injected into the circulating water circuit and the pressure stabilizer 23 under the action of gravity;

[0084] Close the electric switch valves 24 and 26, turn on the electric heating rod of the pressurizer 23, and when the ambient pressure reaches the set value, open the electric switch valve 24, and the water vapor in the pressurizer 23 is discharged into the pressure relief tank 25. Adjust the heating power of the electric heating rod of the pressurizer 23 to keep the ambient temperature and ambient pressure in the pressurizer 23 at the target value and stable.

[0085] In summary, it can be seen from the above description that the above embodiments of the present invention achieve the following technical effects:

[0086] 1. The present invention proposes a test system for the thermal cycle characteristics of multi-directional horizontal pipelines. Through the design of multi-directional pipelines and stabilizers, the system can simulate the thermal cycle characteristics of multi-directional horizontal pipelines under different temperature, pressure, and volume flow conditions, providing comprehensive test data for the design and optimization of nuclear power plant pipelines. The present invention designs thermal cycle tests for downward horizontal pipelines, side horizontal pipelines, and upward horizontal pipelines, thereby covering various thermodynamic conditions that the pipelines may encounter, helping to deeply understand the key characteristics of the thermal cycle phenomenon, such as the cause, location, and duration, and providing an important scientific basis for the safe operation and design optimization of nuclear power plant pipeline systems.

[0087] 2. By adopting high-precision measurement technologies such as paired pressure signal detectors, the system can reduce the reliance on traditional long straight pipe sections without sacrificing measurement accuracy, thereby saving space and material costs. In addition, the compact design of the system reduces the workload of installation and maintenance, further improving the efficiency and economy of the test.

[0088] 3. The present invention proposes a test system for the thermal cycle characteristics of multi-directional horizontal pipes. Since the temperature and pressure increase process of the system is relatively long, the replacement of the multi-directional horizontal pipes must be carried out under normal temperature and pressure conditions, which saves the number of times the multi-directional horizontal pipes are replaced, thereby saving test time and improving the test efficiency of the system. The parallel arrangement of the pipe heaters and the free adjustment of the heating power enable the system to accurately simulate different thermal cycle conditions. At the same time, the system's intelligent control components such as the electric switch valve and the electric regulating valve improve the convenience of operation, make system maintenance and adjustment easier, and reduce maintenance costs and time.

[0089] 4. In the multi-directional horizontal pipeline thermal cycle characteristics test system proposed by the present invention, the pressure stabilizer and pressure relief box design can effectively control and manage pressure fluctuations, further enhancing the safety of the system. In addition, the use of U-shaped communication vessel structure and multi-stage filter ensures the stable operation of the system under high pressure and high temperature conditions, preventing possible equipment damage and accidental interruption of testing.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0091] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0092] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

Claims

1. A test system for thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant, characterized in that: It comprises a circulating water circuit and a pressure stabilizing water circuit, wherein the circulating water circuit comprises multi-directional horizontal pipes (1a, 1b), paired pressure signal detectors (17a, 17b), pipe heaters (14a, 14b, 14c) and a pipe heat exchanger (3), and the pressure stabilizing water circuit comprises a cooling water supply system (18) and a pressure stabilizer (23); The circulating water circuit is connected to the pressure-stabilizing water circuit, the multidirectional horizontal pipes (1a, 1b) have more than two, the more than two multidirectional horizontal pipes (1a, 1b) are arranged in parallel in the circulating water circuit, and electric switch valves (15a, 15b) are respectively arranged upstream of each multidirectional horizontal pipe (1a, 1b); The pipeline heat exchanger (3), the pipeline heater (14a, 14b, 14c) and the multi-directional horizontal pipeline (1a, 1b) are sequentially connected in series in the direction of water flow in the circulating water circuit; there are more than two paired pressure signal detectors (17a, 17b), and the more than two paired pressure signal detectors (17a, 17b) are respectively placed between the multi-directional horizontal pipeline (1a, 1b) and the pipeline heater (14a, 14b, 14c) for measuring pipeline volume flow rate; The cooling water inside the pressure stabilizer (23) of the pressure stabilizing water circuit is injected by the cooling water supply system (18).

2. The system according to claim 1, characterized in that: The multi-directional horizontal pipelines (1a, 1b) include a main pipeline and branch pipelines. The branch pipes are respectively vertically connected to the main pipe at positions of 0°, 180°, 90° or 270° in radial direction.

3. The system according to claim 2, characterized in that: The branch pipeline includes an upward branch pipeline, a downward branch pipeline and a side branch pipeline. The upward branch pipeline is connected to the main pipeline at a radial position of 0°, the downward branch pipeline is connected to the main pipeline at a radial position of 180°, and the side branch pipeline is connected to the main pipeline at a radial position of 90° or 270°.

4. The system according to claim 2, characterized in that: The branch pipelines include vertical pipelines and parallel pipelines. The vertical pipe is vertically connected to the outer surface of the main pipe through one end, and the parallel pipe is parallel to the main pipe and connected to the other end of the vertical pipe.

5. The system according to claim 2, characterized in that: The branch pipeline further includes a blind plate, which is arranged at the end of the branch pipeline.

6. The system according to claim 5, characterized in that: The blind plate comprises two groups of cooling pipes, the inlets of the two groups of cooling pipes are connected to the radial 0° position of the blind plate, and the outlets of the two groups of cooling pipes are respectively connected to the 90° and 270° positions in the circumferential direction of the blind plate.

7. The system according to claim 2, characterized in that: The branch pipeline also includes an electric heating wire and a flange. The electric heating wire is spirally arranged outside the branch pipe, and the flange is arranged at the connection between the branch pipe and the main pipe to realize rotation at different angles.

8. The system according to claim 1, characterized in that: The paired pressure signal detectors (17a, 17b), The two signal detectors in each pair of pressure signal detectors (17a, 17b) are arranged at a fixed distance ranging from 100mm to 300mm in the horizontal direction.

9. The system according to claim 1, characterized in that: The circulating water circuit includes pipeline spoilers (16a, 16b), The pipeline spoilers (16a, 16b) are respectively arranged between the multi-directional horizontal pipelines (17a, 17b) and the pipeline heaters (14a, 14b, 14c).

10. The system according to claim 1, characterized in that: The pipeline heater (14a, 14b, 14c) further includes, There are at least three pipeline heaters (14a, 14b, 14c), the pipeline heaters (14a, 14b, 14c) have at least three different heating powers, and the pipeline heaters (14a, 14b, 14c) are arranged in parallel in the circulating water circuit.

11. The system according to claim 1, characterized in that: The circulating water circuit comprises a multi-stage filter (7) and a circulating pump (8). The multi-stage filter (7) and the circulation pump (8) are arranged in series between the pipeline heat exchanger (3) and the pipeline heater (14a, 14b, 14c); the multi-stage filter (7) is arranged at the water inlet of the circulation pump (8).

12. The system according to claim 1, characterized in that: The circulating water circuit also includes a circulating cooling water system (4), The circulating cooling water system (4) is connected to the shell side of the pipeline heat exchanger (3).

13. The system according to claim 1, characterized in that: The pressure-stabilizing water circuit comprises a pressure relief tank (25), The pressure relief tank (25) is connected to the top of the pressure stabilizer (23) via an electric switch valve (24).

14. The system according to claim 1, characterized in that: The pressure stabilizing water circuit includes a nitrogen supply system (29), The nitrogen supply system (29) is connected to the regulator (23) via an electric switch valve (28).

15. The system according to claim 1, characterized in that: The voltage stabilizer (23) comprises an electric heating rod, The electric heating rods are arranged in a vertical arrangement on the lower end cover of the voltage stabilizer (23).

16. A method for testing thermal cycle characteristics of multi-directional horizontal pipelines in a nuclear power plant using the test system according to any one of claims 1 to 15, characterized in that: include: S1: adjusting the pressure-stabilizing water circuit and the circulating water circuit so that the ambient temperature and ambient pressure in the pressure stabilizer (23) are maintained at target values ​​and are stable; S2: heating the cooling water to a target value according to the pipeline heater (14a, 14b, 14c), measuring the system volume flow according to the paired pressure signal detectors (17a, 17b), and adjusting the system volume flow to reach the target value; Close the electric switch valve (15b) upstream of at least one branch where the multi-directional horizontal pipeline (1b) is located, so that the cooling water flows into at least one other multi-directional horizontal pipeline (1a) for testing; The electric switch valve (15b) upstream of the branch where at least one of the multi-directional horizontal pipes (1b) in a closed state is located is opened, and the electric switch valve (15a) upstream of the branch where at least one of the other multi-directional horizontal pipes (1a) in an open state is closed to conduct a test.

17. The method according to claim 16, characterized in that: The step S2 further includes: After the cooling water enters the multi-directional horizontal pipe (1a), it flows into the downward branch pipe, the side branch pipe and the upward branch pipe in the multi-directional horizontal pipe (1a) in sequence; After the cooling water enters the multi-directional horizontal pipe (1b), it flows into the downward branch pipe, the side branch pipe and the upward branch pipe in the multi-directional horizontal pipe (1b) in sequence.

18. The method according to claim 17, characterized in that: The step S2 further includes: Turn on the electric heating wire outside the branch pipe, and adjust the temperature of the outer wall and blind plate of the branch pipe to the target value and stabilize it.

19. The method according to claim 16, characterized in that: The step S2 further includes: The circulating cooling water system (4) is turned on, and the cooling water on the shell side of the pipeline heat exchanger (3) is continuously circulated at a small volume flow rate.

20. The method according to claim 16, characterized in that: The step S1 further includes: Opening the electric switch valve (19) of the pressure-stabilizing water circuit, starting the cooling water supply system (18), injecting cooling water into the cooling water tank (20), and after the cooling water in the cooling water tank (20) reaches the target liquid level and stabilizes, closing the cooling water supply system (18), opening the electric switch valve (2, 6, 12, 13a, 13b, 13c, 15a, 15b, 21, 24, 26, 27) and the electric regulating valve (10, 11), and injecting the cooling water in the cooling water tank (20) into the circulating water circuit and the pressure stabilizer (23) under the action of gravity; The electric switch valves (24, 26) are closed, and the electric heating rod of the voltage stabilizer (23) is turned on. When the ambient pressure reaches a set value, the electric switch valve (24) is opened, and the water vapor in the voltage stabilizer (23) is discharged into the pressure relief box (25). The heating power of the electric heating rod of the voltage stabilizer (23) is adjusted so that the ambient temperature and ambient pressure in the voltage stabilizer (23) are maintained at target values ​​and are stable.

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