An experimental device for studying scaling behavior
By designing an experimental device for a dual-circuit high-pressure system and simulating the flow velocity and Karman vortex street effect of the heat transfer tubes and support plates of a nuclear power plant, the problem of large deviation in experimental data was solved, and accurate measurement of the relationship between flow velocity and micropore area was achieved, supporting the efficient operation of the nuclear power plant.
Patent Information
- Application Number
- CN202210029974.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-01-12
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2042-01-12
AI Technical Summary
Existing experimental equipment is unable to simulate the actual flow velocity and Karman vortex street effect between the heat transfer tubes and support plates of nuclear power plants, resulting in large deviations in experimental data and an inability to accurately understand the relationship between flow velocity changes and pore residual area, affecting the operating efficiency and maintenance cycle of nuclear power plants.
An experimental device consisting of a water storage tank, a first loop, a second loop, and a third loop was designed. A high-pressure pump and a circulating pump were used to form a dual-loop high-pressure system. The residual area of the sample micropores was inferred by monitoring the flow rate changes, simulating the actual operating conditions of a nuclear power plant.
It has achieved the simulation of the high flow rate conditions of nuclear power plants in the laboratory, and can accurately obtain the relationship between flow rate changes and micropore residual area, providing a scientific basis for nuclear power plant maintenance, reducing the number of unnecessary shutdowns and maintenance, and improving operating efficiency.
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Figure CN114496320B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of high-temperature and high-pressure water experiments, and in particular to an experimental device for studying scaling behavior. Background Art
[0002] Nuclear power, as a highly efficient and clean energy source, has long garnered significant attention. Pressurized water reactors (PWRs) are the primary reactor type currently used in commercial nuclear power plants. During long-term operation, fouling forms on the surfaces of steam generator heat transfer tubes, reducing heat transfer efficiency. Blockage is typically most severe at the trilobed pores between the heat transfer tubes and the support plate. This reduction in pore area also increases the flow rate of water passing through these pores, causing a severe Karman vortex street effect. This, in turn, accelerates corrosion of the support plate, worsening the local water chemistry and leading to even more severe corrosion. This in turn exacerbates scaling between the heat transfer tubes and the support plate, affecting the pore area. Changes in pore area between the heat transfer tubes and the support plate can lead to changes in flow rate.
[0003] At present, the relationship between the change in flow velocity and the residual area of the pores is still unclear. If the relationship between the change in flow velocity and the residual area of the pores can be given, it will provide a strong basis for the shutdown maintenance cycle of nuclear power plants, reduce the number of unnecessary shutdowns for maintenance, and also improve the operating efficiency of nuclear power plants.
[0004] Typically, scaling behavior between heat transfer tubes and support plates is simulated in the laboratory by assembling the tubes and support plates according to their actual service assembly method, then immersing them in a high-temperature, high-pressure device. Water is then supplied to the entire high-pressure circuit via a high-pressure pump. However, the flow rate of the high-pressure pump is usually very low, which cannot reach the flow rate of actual operating conditions in nuclear power plants and the Karman vortex street effect. Furthermore, during the simulation process, it is impossible to ensure that water flows completely through the pores between the heat transfer tubes and the support plates, resulting in large deviations in the simulated experimental data. Summary of the Invention
[0005] In order to solve at least one of the above technical problems, the present invention provides an experimental device for studying scaling behavior, and the technical solution adopted is as follows.
[0006] The experimental device for studying scaling behavior provided by the present invention includes a water storage tank, a first loop, a second loop and a third loop, wherein the first loop is connected to the inlet and outlet of the water storage tank, and the first loop includes a first back pressure valve and a first flow meter; the second loop includes a heat exchanger, a condenser, a second back pressure valve and a second flow meter, the condenser is connected to the heat exchanger, the second back pressure valve and the second flow meter are arranged on the pipeline between the condenser and the inlet of the water storage tank, and the heat exchanger is connected to the outlet of the water storage tank; the third loop includes an autoclave, a preheater and a circulation component, the outlet of the autoclave is connected to the heat exchanger, the inlet of the autoclave is connected to the preheater, and the preheater is connected to the heat exchanger; a sample can be set in the circulation component, and the circulation component is arranged at the outlet of the autoclave.
[0007] In certain embodiments of the present invention, the flow component includes a first connecting piece and a second connecting piece, wherein the first connecting piece is connected to the outlet of the autoclave, and the second connecting piece is fixedly installed to the first connecting piece to fix the sample in the flow component.
[0008] In some embodiments of the present invention, the second connecting member is threadedly connected to the first connecting member.
[0009] In some embodiments of the present invention, the experimental device includes a high-pressure pump, which is disposed at the outlet of the water storage tank and is connected to the first circuit and the second circuit respectively.
[0010] In certain embodiments of the present invention, the experimental device includes a circulation pump, which is disposed at the outlet of the water storage tank and is connected to the high-pressure pump.
[0011] In some embodiments of the present invention, the first flow meter is configured as a metal flow meter.
[0012] In some embodiments of the present invention, the second flow meter is configured as a metal flow meter.
[0013] The embodiments of the present invention have at least the following beneficial effects: In the experimental apparatus, a first circuit and a second circuit are designed to form a dual-circuit high-pressure system. By monitoring the flow rate changes in the first and second circuits, the changes in the residual area of the sample micropores can be inferred, and the relationship between the flow rate changes and the residual area of the micropores can be obtained. The present invention can be widely applied to the field of high-temperature and high-pressure water experimental technology. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments with reference to the accompanying drawings.
[0015] Figure 1Schematic diagram of the experimental device. DETAILED DESCRIPTION
[0016] The following combination Figure 1 Embodiments of the present invention are described in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.
[0017] In the description of the present invention, it should be understood that if the terms "center", "middle", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The features defined as "first" and "second" are used to distinguish the feature names, and do not have special meanings. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.
[0018] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.
[0019] The present invention relates to an experimental device for studying scaling behavior. The device can implement a high-flow-rate dual-loop simulation system. With minimal modifications, it can simulate the flow rates of actual nuclear power plant operating conditions in the laboratory, reducing costs. The experimental device includes a water storage tank 101, a first loop, and a second loop. The first loop is connected to the inlet and outlet of the water storage tank 101, and the second loop is connected to the inlet and outlet of the water storage tank 101.
[0020] In conjunction with the accompanying drawings, the experimental device includes a high-pressure pump 111, which is arranged at the outlet of the water storage tank 101 and is connected to the first circuit and the second circuit respectively. Furthermore, the experimental device includes a circulation pump 112, which is arranged at the outlet of the water storage tank 101 and is connected to the high-pressure pump 111.
[0021] The first circuit includes a first back pressure valve 102 and a first flow meter 103 . The first flow meter 103 is configured as a metal flow meter with a metal float. Specifically, the first back pressure valve 102 is connected to the high pressure pump 111 , and the first flow meter 103 is connected to the first back pressure valve 102 .
[0022] The second circuit includes a heat exchanger 104, a condenser 105, a second back pressure valve 106 and a second flow meter 107. Specifically, the heat exchanger 104 is connected to the outlet of the water storage tank 101, the condenser 105 is connected to the heat exchanger 104, and the condenser 105 is arranged on the pipeline between the heat exchanger 104 and the outlet of the water storage tank 101. The second back pressure valve 106 and the second flow meter 107 are arranged on the pipeline between the condenser 105 and the inlet of the water storage tank 101. The second flow meter 107 is set as a metal flow meter with a metal float.
[0023] The third loop includes an autoclave 108 and a preheater 109. Specifically, the outlet of the autoclave 108 is connected to the heat exchanger 104, the inlet of the autoclave 108 is connected to the preheater 109, and the preheater 109 is connected to the heat exchanger 104. The third loop can cool the water in the second loop.
[0024] The third circuit includes a flow component 110, located at the outlet of the autoclave 108. Flow component 110 is hollow, forming a waterway. The sample, a sheet-like structure with micropores, can be placed in flow component 110, allowing water in the autoclave 108 to flow out through flow component 110. Specifically, the micropore is located in the center of the sample and has a diameter of 100 to 300 μm. It is understood that the area around the micropore should be cleaned of burrs to avoid affecting experimental results.
[0025] When water flows through the micropores in the flow component 110, the pressure difference between the water inlet and the water outlet of the flow component 110 is large. According to the Bernoulli equation, it can be concluded that when water passes through the micropores of the sample, the water flow velocity can reach a very high value, resulting in a very obvious Karman vortex street effect, which is consistent with the water flow velocity in the nuclear power plant. The water flow velocity can reach the m / s level, which can simulate the actual operating conditions of the nuclear power plant.
[0026] In order to monitor the residual area of the sample micropores in real time, the experimental device is designed to have a first loop and a second loop to form a high-pressure end double-loop system, in which the first loop mainly plays a diversion role.
[0027] The flow component 110 includes a first connecting piece and a second connecting piece. The first connecting piece is connected to the outlet of the autoclave 108, and the second connecting piece is fixedly mounted to the first connecting piece to secure the sample in the flow component 110. The first and second connecting pieces are each provided with a hollow channel that can form a water path with the sample's micropores. It will be appreciated that the design of the flow component 110 with the first and second connecting pieces facilitates the installation and securing of the sample. In some examples, the second connecting piece is threadedly connected to the first connecting piece.
[0028] Specifically, the first end of the first connecting piece is socketed with the water outlet pipe of the autoclave 108, the second end of the first connecting piece is provided with an internal thread, and the first end of the second connecting piece is provided with an external thread. It can be understood that the second end of the first connecting piece is threadedly connected to the first end of the second connecting piece, and the second end of the first connecting piece and the first end of the second connecting piece press and fix the sample.
[0029] After the experiment is complete, the sample is removed and the overall corrosion level can be used to determine whether water is leaking solely from the micropores. If water is leaking solely from the micropores, the outer ring of the sample (where the second connecting piece presses) will retain the original metal color. This allows for quick identification of the accuracy of the simulation results.
[0030] Before the experiment begins, tighten the high-pressure valve and adjust the water chemical parameters to meet the experimental requirements. During the experiment, turn on the high-pressure pump 111, and water will flow back from the first circuit and the second circuit to the water storage tank 101 respectively.
[0031] The specific operations of the experiment are as follows:
[0032] Turn on high-pressure pump 111, allowing water to flow through the second circuit. Simultaneously, both first flowmeter 103 and second flowmeter 107 register a certain flow rate. At this point, adjust first backpressure valve 102 and second backpressure valve 106 simultaneously to bring the pressures in both the first and second circuits to 10 MPa. Since the pressures in the first and second circuits are roughly the same, and according to Bernoulli's equation, the flow rates in first flowmeter 103 and second flowmeter 107 are also roughly the same, at 5 L / h.
[0033] Continuing to increase the pressure of the first back pressure valve 102 causes the reading of the first flow meter 103 to gradually drop to 2.5 L / h, while also causing the reading of the second flow meter 107 to rise to 7.5 L / h.
[0034] After adjustment and stabilization, the temperature was raised to 290° C. It was observed that the pressure at the water inlet of the autoclave 108 was significantly greater than the pressure at the water outlet. The pressure difference could be monitored by a pressure sensor.
[0035] The Bernoulli equation can be used to calculate the water velocity through the sample micropores based on the pressure difference. According to the continuity equation for incompressible fluids, the flow rate monitored by the second flowmeter 107 divided by the water velocity at the sample micropores can be used to obtain the real-time residual area of the sample micropores.
[0036] After the experimental device has been running stably for a period of time, it can be found that the reading of the second flow meter 107 has been in a decreasing state, and the reading of the first flow meter 103 has been in an increasing state, indicating that the micropore area of the sample in the flow component 110 is gradually decreasing.
[0037] After the experimental device stops running, the sample is taken out and the size of the residual area of the sample's micropores is observed under a metallographic microscope to obtain the area of the sample's micropores blocked by corrosion products.
[0038] Through multiple sets of experiments, the relationship between the residual area of the sample micropores and the flow rate change can be obtained. Therefore, the flow rate change can be used to know the residual area of the gap between the heat transfer tubes and the support plate in the secondary circuit of the nuclear power plant. This also provides a strong basis for cleaning the corrosion products between the heat transfer tubes and the support plate in the secondary circuit of the nuclear power plant.
[0039] The experimental device involved in the present invention can make the water flow velocity under high temperature and high pressure in the laboratory reach the level of m / s, can simulate the actual operating conditions of the nuclear power plant, and can produce obvious Karman vortex street phenomenon.
[0040] The equipment in the related art has only one circuit and only one return water outlet, while the experimental device involved in the present invention has two circuits, a first circuit and a second circuit, and two water outlets on the autoclave 108. The advantage of the dual circuit is that it can record the flow changes in both circuits in real time. During the experiment, due to the significant Karman vortex street effect at the micropores of the sample, it can accelerate the corrosion of the material and release a large amount of iron ions. These iron ions can be deposited in the micropores, resulting in a reduction in the micropore area, which in turn causes changes in the flow rate in the first and second circuits.
[0041] Although the change in micropore area cannot be directly observed during the test, the size of the micropore residual area can be inferred from the change in flow rate and flow rate, and ultimately the relationship between flow rate change and micropore residual area can be obtained.
[0042] Throughout this specification, references to "one embodiment," "some examples," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" refer to specific features, structures, materials, or characteristics described in conjunction with the embodiment or example in at least one embodiment or example of the present invention. In this specification, the illustrative use of these terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
[0043] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present invention.
Claims
1. An experimental device for studying scaling behavior, characterized by: include Water storage tank (101); a first circuit connected to the inlet and outlet of the water storage tank (101), the first circuit comprising a first back pressure valve (102) and a first flow meter (103); a second circuit, the second circuit comprising a heat exchanger (104), a condenser (105), a second back pressure valve (106) and a second flow meter (107); the condenser (105) is connected to the heat exchanger (104); the second back pressure valve (106) and the second flow meter (107) are arranged on a pipeline between the condenser (105) and the inlet of the water storage tank (101); and the heat exchanger (104) is connected to the outlet of the water storage tank (101); a third circuit, the third circuit comprising an autoclave (108), a preheater (109), and a flow component (110), wherein the outlet of the autoclave (108) is connected to the heat exchanger (104), the inlet of the autoclave (108) is connected to the preheater (109), and the preheater (109) is connected to the heat exchanger (104); The flow component (110) is capable of being provided with a sample, and the flow component (110) is provided at the outlet of the autoclave (108); the flow component (110) comprises a first connecting piece and a second connecting piece, wherein the first connecting piece is connected to the outlet of the autoclave (108), and the second connecting piece is fixedly installed with the first connecting piece to fix the sample in the flow component (110).
2. The experimental device for studying scaling behavior according to claim 1, characterized in that: The second connecting piece is threadedly connected to the first connecting piece.
3. The experimental device for studying scaling behavior according to claim 1, characterized in that: The experimental device comprises a high-pressure pump (111), wherein the high-pressure pump (111) is arranged at the outlet of the water storage tank (101), and the high-pressure pump (111) is connected to the first circuit and the second circuit respectively.
4. The experimental device for studying scaling behavior according to claim 3, characterized in that: The experimental device comprises a circulation pump (112), wherein the circulation pump (112) is arranged at the outlet of the water storage tank (101), and the circulation pump (112) is connected to the high-pressure pump (111).
5. The experimental device for studying scaling behavior according to claim 1, characterized in that: The first flow meter (103) is configured as a metal flow meter.
6. The experimental device for studying scaling behavior according to claim 1, characterized in that: The second flow meter (107) is configured as a metal flow meter.