Steady state loop system and passive flow distribution method under thermal state working condition of system

Abstract

The invention relates to the technical field of irradiation, in particular to a steady-state loop system and a passive flow distribution method under a system thermal state working condition, flow distribution is achieved based on combination of active and passive design, a bypass branch in the steady-state loop system is provided with an electromagnetic valve, a sensor used for sensing the temperature of a test piece is arranged in a test body, and the temperature of the test piece is measured through the electromagnetic valve. The temperature sensor is electrically connected with the controller, the controller is electrically connected with the electromagnetic valve, and the flow of the bypass channel is controlled based on the temperature of the test piece; the interface form of the test piece is changed into a round shape through the square-to-round joint, and the bottom of the test piece and the lower tube seat matched with the square-to-round joint are configured to be in clearance fit with the inner wall of the round end under the cold-state working condition and in transition fit with the inner wall of the round end under the hot-state working condition. According to the method, the accuracy of flow distribution of the steady-state loop system under the hot-state working condition can be improved, the deviation between the actual flow and the designed flow is reduced, the fluctuation of the actual flow under the hot-state working condition is reduced, and the test safety and the accuracy of a test result are improved.

Description

Technical Field

[0001] The present invention relates to the field of irradiation technology, and in particular to a steady-state loop system and a passive flow distribution method under hot working conditions of the system. Background Art

[0002] At present, the types of research reactors are becoming more and more diverse, including heavy water reactors, light water reactors, gas-cooled reactors, metal reactors and nuclear fusion reactors under development. The configuration of the loop system varies greatly for different reactor types. For the same reactor type, many loop settings are indispensable and can be borrowed from each other, but each reactor has its own characteristics, so each loop should be designed according to the specific conditions of the reactor. In order to carry out irradiation tests on fuels and materials, research reactors usually need to build supporting loop systems. For example, the HFETR reactor has built a 2000kW high-temperature and high-pressure loop system. When using research reactors and test loops to carry out irradiation tests on test pieces, the coolant flow required for the test needs to be calculated based on the thermal parameters and physical parameters of the test pieces. When loading the test pieces, due to assembly gaps and manufacturing deviations, part of the loop coolant flows out of the gaps, causing the actual flow to be smaller than the designed flow.

[0003] To deal with the above problems, the strategies adopted at home and abroad are to carry out hydraulic calculations or flow calibration tests, and then correct the design flow after obtaining the deviation results. However, under hot conditions, due to changes in coolant temperature, pressure, and core changes, under the action of pressure, thermal expansion, and radiation swelling, the direction of change of assembly clearance and manufacturing deviation is uncontrollable, making the actual test value inconsistent with the calculated value and calibration value, which may cause the flow distribution to be out of control. Another strategy is to establish an active flow distribution method based on the power of the test piece, use the power of the test piece to reverse the real-time coolant flow of the test piece and dynamically adjust the total flow, which can achieve the above purpose. However, this method has high requirements on the accuracy of power calculation, and real-time adjustment may cause the flow to exceed the permitted range.

[0004] Therefore, it is necessary to establish a passive flow distribution method under thermal conditions of a steady-state loop system. Summary of the invention

[0005] The purpose of the present invention is to provide a steady-state loop system and a non-active flow distribution method under the hot condition of the system. Without relying on external input, the flow distribution of the test piece is performed by relying on pressure, thermal expansion, radiation swelling and adjusting the flow of the bypass channel according to the temperature of the test piece, thereby realizing non-active flow distribution under the hot condition of the steady-state loop system. On the one hand, it can improve the accuracy of flow distribution under the hot condition of the steady-state loop system and reduce the deviation between the actual flow and the designed flow. On the other hand, it can reduce the fluctuation of the actual flow under the hot condition and improve the safety of the test and the accuracy of the test results.

[0006] The present invention is implemented through the following technical solutions: A steady-state loop system includes a test pipeline, a test body and a controller, wherein the test body is connected to the test pipeline through a connecting pipeline; wherein,

[0007] The test pipeline includes a mainstream pipeline and a bypass branch, one end of the mainstream pipeline is connected to the inlet of the mainstream channel in the test body, and the other end of the mainstream pipeline is connected to the outlet of the mainstream channel in the test body, one end of the bypass branch is connected to the inlet of the bypass channel in the test body, and the other end of the bypass branch is connected to the outlet of the bypass channel in the test body;

[0008] The test body comprises a shell, a test piece and a square-to-round joint, the test piece and the square-to-round joint are arranged in the shell, a lower tube seat with a circular cross-section is arranged at the bottom of the test piece, the lower tube seat is arranged on the inner side of the circular end of the square-to-round joint, the lower tube seat is configured to be gap-matched with the inner wall of the circular end under cold working conditions, and transitionally matched with the inner wall of the circular end under hot working conditions, the lower tube seat is provided with an axial water gap along the axis, the axial water gap is connected to the main flow channel in the test body, the lower tube seat is provided with an annular water gap along the axial direction, the annular water gap is connected to the bypass flow channel in the test body;

[0009] The bypass branch is provided with a solenoid valve, the test body is provided with a temperature sensor for sensing the temperature of the test piece, the temperature sensor is electrically connected to the controller, and the controller is electrically connected to the solenoid valve.

[0010] According to a preferred embodiment, a mass flow meter is further provided on the bypass branch, and the mass flow meter is arranged on the inlet side of the solenoid valve.

[0011] According to a preferred embodiment, a flow blocking groove is provided in the fitting gap between the square-to-round joint and the lower pipe seat.

[0012] According to a preferred embodiment, the flow blocking groove is opened on the outer side of the lower pipe seat.

[0013] According to a preferred embodiment, the flow blocking groove is one of a rectangular groove, a trapezoidal groove, a sawtooth groove, a stepped groove and a wave groove.

[0014] According to a preferred embodiment, an electric heater is provided on the test pipeline, and the electric heater is arranged at the inlet side of the test body.

[0015] According to a preferred embodiment, a heat exchanger is further provided on the test pipeline, and the heat exchanger is arranged on the outlet side of the test body.

[0016] According to a preferred embodiment, the mainstream pipeline includes a main pump, a make-up water pump and a pressure stabilizer, the main pump outlet is respectively connected to the pressure stabilizer inlet and the electric heater inlet, the main pump inlet is respectively connected to the heat exchanger outlet and the pressure stabilizer outlet, the inlet of the make-up water pump is connected between the main pump inlet and the heat exchanger outlet, and the outlet of the make-up water pump is connected between the main pump outlet and the electric heater inlet.

[0017] The present invention also provides a passive flow distribution method under hot conditions for the steady-state loop system as described above, comprising:

[0018] Get the temperature of the test piece in real time;

[0019] When the temperature of the test piece is higher than or lower than a preset temperature value, a design flow rate corresponding to the temperature of the test piece is obtained, the opening of the solenoid valve is adjusted according to the design flow rate, and the flow rate is monitored using a mass flow meter, wherein when the temperature of the test piece is higher than the preset temperature value, the opening of the solenoid valve increases, and when the temperature of the test piece is lower than the preset temperature value, the opening of the solenoid valve decreases.

[0020] According to a preferred embodiment, before obtaining the temperature of the test piece, the method further includes:

[0021] Start the main pump and electric heater, and put the water supply pump and heat exchanger into operation;

[0022] Determine whether the test pipeline pressure is stable. If not, start the water supply pump to supply water until the pressure is stable and then close the water supply pump;

[0023] If yes, set the main pump frequency and obtain the temperature of the test piece.

[0024] The technical solution of a steady-state loop system and a non-active flow distribution method under hot conditions of the system provided by the present invention has at least the following advantages and beneficial effects: the present invention performs flow distribution on the test piece by relying on pressure, thermal expansion, radiation swelling and adjusting the flow of the bypass channel according to the temperature of the test piece without relying on external input, thereby realizing non-active flow distribution under hot conditions of the steady-state loop system. On the one hand, it can improve the accuracy of flow distribution under hot conditions of the steady-state loop system and reduce the deviation between the actual flow and the designed flow. On the other hand, it can reduce the fluctuation of the actual flow under hot conditions and improve the safety of the test and the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a steady-state loop system provided in Example 1 of the present invention;

[0026] Figure 2 A schematic diagram of the structure of the test body provided in Example 1 of the present invention;

[0027] Figure 3 A schematic cross-sectional view of a lower tube seat provided in Example 1 of the present invention;

[0028] Figure 4 A schematic diagram of the opening of the flow blocking groove provided in Example 1 of the present invention;

[0029] Figure 5 A schematic diagram of a change in a passive assembly gap provided in Example 1 of the present invention;

[0030] Figure markings: 1-test body, 11-test piece, 111-lower pipe seat, 112-axial water gap, 113-annular water gap, 114-blocking groove, 12-square to round joint, 13-temperature sensor, 14-bypass channel, 2-test pipeline, 21-main pipeline, 211-main pump, 212-water supply pump, 213-pressure regulator, 22-bypass branch, 221-solenoid valve, 222-mass flowmeter, 223-controller, 23-electric heater, 24-heat exchanger. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Example 1

[0033] Figure 1 This is a schematic diagram of the structure of the steady-state loop system provided by an embodiment of the present invention. Figure 1 As shown, the steady-state loop system includes a test pipeline 2, a test body 1 and a PLC controller 223, and the test body 1 is connected to the test pipeline 2 through a connecting pipeline.

[0034] The test pipeline 2 includes a mainstream pipeline 21 and a bypass branch 22; one end of the mainstream pipeline 21 is connected to the inlet of the mainstream channel in the test body 1, and the other end of the mainstream pipeline 21 is connected to the outlet of the mainstream channel in the test body 1; one end of the bypass branch 22 is connected to the inlet of the bypass channel 14 in the test body 1, and the other end of the bypass branch 22 is connected to the outlet of the bypass channel 14 in the test body 1.

[0035] The test pipeline 2 is provided with an electric heater 23 and a heat exchanger 24 ; the electric heater 23 is arranged at the inlet side of the test body 1 , and the heat exchanger 24 is arranged at the outlet side of the test body 1 .

[0036] The mainstream pipeline 21 includes a main pump 211, a make-up water pump 212 and a pressure regulator 213; the outlet of the main pump 211 is respectively connected to the inlet of the pressure regulator 213 and the inlet of the electric heater 23, and the inlet of the main pump 211 is respectively connected to the outlet of the heat exchanger 24 and the outlet of the pressure regulator 213; the inlet of the make-up water pump 212 is connected between the inlet of the main pump 211 and the outlet of the heat exchanger 24, and the outlet of the make-up water pump 212 is connected between the outlet of the main pump 211 and the inlet of the electric heater 23.

[0037] This embodiment realizes flow distribution under hot conditions of a steady-state loop system based on a combination of active and passive designs.

[0038] The passive design part of this embodiment is described below:

[0039] Regarding the difference between the test body 1 and the test piece 11, this embodiment transforms the assembly gap of the test piece 11 from the traditional square or hexagonal shape to a circle through a transition section, and increases the coolant flow resistance by lengthening the assembly length of the test piece 11. The above design reduces the deviation between the design flow and the actual flow at the design end. It should be noted that the assembly length needs to be adjusted according to the specific form of the test piece 11. If the length is too short, the passive flow distribution effect under hot conditions will be reduced, resulting in an increase in flow deviation. If the length is too long, it will increase the difficulty of assembly, which is not conducive to the assembly and disassembly of the test piece 11.

[0040] For specific design, see Figure 2 As shown, in this embodiment, the test body 1 includes a shell, a test piece 11 and a square-to-round joint 12, and the test piece 11 and the square-to-round joint 12 are arranged in the shell; a lower tube seat 111 with a circular cross-section is provided at the bottom of the test piece 11, and the joint of the test piece 11 is changed to a circular shape, and the lower tube seat 111 is arranged on the inner side of the circular end of the square-to-round joint 12, and the lower tube seat 111 is configured to be in clearance fit with the inner wall of the circular end under cold working conditions, and to be transition fit with the inner wall of the circular end under hot working conditions. It should be noted that by changing the shape of the assembly gap, the assembly accuracy can be improved, and the gap width can be reduced under the premise of the same manufacturing level.

[0041] See also Figure 3 As shown, the lower tube seat 111 has an axial water gap 112 along the axis, the axial water gap 112 is connected to the main flow channel in the test body 1, and the lower tube seat 111 has an annular water gap 113 along the axial direction, the annular water gap 113 is connected to the bypass channel 14 in the test body 1.

[0042] See also Figure 4As shown, this embodiment further increases the flow resistance of the assembly gap of the test piece 11, and a blocking groove 114 is provided in the matching gap between the square-to-round joint 12 and the lower tube seat 111. The blocking groove 114 is opened on the outer side of the lower tube seat 111, and the blocking groove 114 is one of a rectangular groove, a trapezoidal groove, a sawtooth groove, a stepped groove and a wave groove. In addition to the above-mentioned method of increasing the roughness of the assembly gap, the method of increasing the flow resistance of the assembly gap of the test piece 11 can also be to reduce the design width of the assembly gap, increase the design length of the assembly gap, etc., which will not be described in detail here.

[0043] It should be noted that the heat generated by the test piece 11 in the steady-state loop system will change at different stages. Under the premise of constant flow rate and pressure, the temperature increase will lead to a decrease in the coolant medium density, thereby causing the flow rate to increase under the premise of constant flow rate. This embodiment uses the characteristics of the main bypass flow distribution channel at the coolant inlet of the test piece 11 to design the cross-section of the main channel to be circular and the cross-section of the bypass flow channel 14 to be circular; see Figure 5 As shown, when the temperature rises, since the wall thickness of the annular solid between the mainstream channel and the bypass channel 14 is larger and the wall thickness of the annular solid outside the bypass channel 14 is smaller, the thermal expansion of the annular solid between the mainstream channel and the bypass channel 14 is larger, causing the cross-sectional ratio of the mainstream channel to the bypass channel 14 to decrease, thereby increasing the bypass flow and reducing the mainstream.

[0044] Furthermore, at the manufacturing end, the manufacturing accuracy of the square-to-circular joint 12 is increased, and the upper and lower deviations of the fitting clearance are reduced; in one implementation of the present embodiment, the interface accuracy is increased to IT6 level, and the upper and lower deviations are controlled to ±0.022mm; the cylindricality of the interface is controlled so that the difference between the maximum and minimum dimensions of any vertical section is ≤0.01mm; the concentricity of the annular water gap 113 of the interface is controlled so that the circular offset distance of any vertical section of the interface is ≤0.01mm; the above design reduces the deviation between the design flow and the actual flow at the manufacturing end and reduces the actual flow fluctuation under hot conditions.

[0045] It should be noted that, based on the above design, there is an "elimination of gap" phenomenon in the hot fit clearance of the axial hole of the square-to-circular joint 12, and the gap will be further reduced under hot conditions. Under high-pressure conditions, the steady-state circuit system is in a high-pressure state, and the coolant flowing through the annular water gap 113 will form a pressure difference between the upper and lower sections. This pressure difference is greater than the pressure difference at the same position of the test piece 11, which can reduce the sensitivity of the flow to the deformation of the annular water gap 113; under hot conditions, the annular water gap 113 will produce thermal expansion under the action of temperature, and the expansion direction is radially outward, but there is an "elimination of gap" phenomenon, which makes the fit clearance between the lower pipe seat 111 and the square-to-circular joint 12 reduce in the hot state. The higher the temperature, the closer the actual flow is to the design flow. Nearly; by coordinating the design size, design temperature, and thermal expansion coefficient, the lower tube seat 111 and the square-to-round joint 12 under cold conditions can be matched in a clearance fit, with a reference value of 0.1mm; the lower tube seat 111 and the square-to-round joint 12 under hot conditions can be matched in a transition fit, with a gap of 0mm; the thermal expansion difference of the lower tube seat 111 under hot conditions is equal to the design gap value; under radiation conditions, the square-to-round joint 12 may irradiate and swell under the bombardment of the neutron field, and the swelling will also cause the "gap elimination" phenomenon to occur.

[0046] In summary, the present invention performs flow distribution on the test piece 11 by relying on pressure, thermal expansion, radiation swelling and adjusting the flow of the bypass channel 14 according to the temperature of the test piece 11 without relying on external input, thereby realizing non-active flow distribution under hot conditions of the steady-state loop system. On the one hand, it can improve the accuracy of flow distribution under hot conditions of the steady-state loop system and reduce the deviation between the actual flow and the designed flow. On the other hand, it can reduce the fluctuation of the actual flow under hot conditions and improve the safety of the test and the accuracy of the test results.

[0047] The active design part of this embodiment is described below:

[0048] In this embodiment, a solenoid valve 221 and a mass flowmeter 222 are provided on the bypass branch 22, and the mass flowmeter 222 is arranged on the inlet side of the solenoid valve 221; a temperature sensor 13 for sensing the temperature of the test piece 11 is provided in the test body 1, and the temperature sensor 13 is electrically connected to the controller 223, and the controller 223 and the mass flowmeter 222 are both electrically connected to the solenoid valve 221.

[0049] In this embodiment, the passive flow distribution method under hot working conditions of the steady-state loop system includes the following steps:

[0050] Step 1: obtaining the temperature of the test piece 11 in real time through the temperature sensor 13;

[0051] Step 2: when the temperature of the test piece 11 is higher or lower than a preset temperature value, obtain a design flow rate corresponding to the temperature of the test piece 11;

[0052] Step three, adjust the opening of the solenoid valve 221 according to the design flow rate, and use the mass flowmeter 222 to monitor the flow rate; when the temperature of the test piece 11 is higher than the preset temperature value, the opening of the solenoid valve 221 increases (the higher the temperature of the test piece 11, the larger the battery valve opening); when the temperature of the test piece 11 is lower than the preset temperature value, the opening of the solenoid valve 221 decreases (the lower the temperature of the test piece 11, the smaller the battery valve opening), thereby maintaining the flow rate stability under the hot condition of the steady-state loop system.

[0053] Furthermore, before obtaining the temperature of the test piece 11, the method also includes: starting the main pump 211 and the electric heater 23, and putting the water supply pump 212 and the heat exchanger 24 into operation; further, determining whether the pressure of the test pipeline 2 is stable, if not, starting the water supply pump 212 to supply water, and then shutting down the water supply pump 212 after the pressure stabilizes; if so, setting the frequency of the main pump 211 and obtaining the temperature of the test piece 11.

[0054] The above are only preferred embodiments of the present invention and are 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.

Claims

1. A steady-state loop system, characterized in that: It comprises a test pipeline (2), a test body (1) and a controller (223), wherein the test body (1) is connected to the test pipeline (2) via a connecting pipeline; wherein: The test pipeline (2) comprises a main flow pipeline (21) and a bypass branch (22), one end of the main flow pipeline (21) is connected to the inlet of the main flow channel in the test body (1), and the other end of the main flow pipeline (21) is connected to the outlet of the main flow channel in the test body (1), one end of the bypass branch (22) is connected to the inlet of the bypass flow channel (14) in the test body (1), and the other end of the bypass branch (22) is connected to the outlet of the bypass flow channel (14) in the test body (1); The test body (1) comprises a shell, a test piece (11) and a square-to-round joint (12). The test piece (11) and the square-to-round joint (12) are arranged in the shell. A lower tube seat (111) with a circular cross-section is provided at the bottom of the test piece (11). The lower tube seat (111) is arranged on the inner side of the circular end of the square-to-round joint (12). The lower tube seat (111) is configured to be clearance-matched with the inner wall of the circular end under cold working conditions and transitionally matched with the inner wall of the circular end under hot working conditions. The lower tube seat (111) is provided with an axial water gap (112) along the axis. The axial water gap (112) is connected to the main flow channel in the test body (1). The lower tube seat (111) is provided with an annular water gap (113) along the axial direction. The annular water gap (113) is connected to the bypass flow channel (14) in the test body (1); The bypass branch (22) is provided with a solenoid valve (221), and the test body (1) is provided with a temperature sensor (13) for sensing the temperature of the test piece (11). The temperature sensor (13) is electrically connected to a controller (223), and the controller (223) is electrically connected to the solenoid valve (221).

2. The steady-state loop system according to claim 1, characterized in that: The bypass branch (22) is also provided with a mass flow meter (222), and the mass flow meter (222) is arranged on the inlet side of the solenoid valve (221).

3. The steady-state loop system according to claim 1, characterized in that: A flow blocking groove (114) is provided in the matching gap between the square-to-round joint (12) and the lower pipe seat (111).

4. The steady-state loop system according to claim 3, characterized in that: The flow blocking groove (114) is arranged on the outer side of the lower pipe seat (111).

5. The steady-state loop system according to claim 3, characterized in that: The flow blocking groove (114) is one of a rectangular groove, a trapezoidal groove, a sawtooth groove, a stepped groove and a wave groove.

6. The steady-state loop system according to any one of claims 2 to 5, characterized in that: The test pipeline (2) is provided with an electric heater (23), and the electric heater (23) is arranged on the inlet side of the test body (1).

7. The steady-state loop system according to claim 6, characterized in that: The test pipeline (2) is also provided with a heat exchanger (24), and the heat exchanger (24) is arranged on the outlet side of the test body (1).

8. The steady-state loop system according to claim 7, characterized in that: The main flow pipeline (21) comprises a main pump (211), a water replenishment pump (212) and a pressure stabilizer (213); the outlet of the main pump (211) is respectively connected to the inlet of the pressure stabilizer (213) and the inlet of the electric heater (23); the inlet of the main pump (211) is respectively connected to the outlet of the heat exchanger (24) and the outlet of the pressure stabilizer (213); the inlet of the water replenishment pump (212) is connected between the inlet of the main pump (211) and the outlet of the heat exchanger (24); and the outlet of the water replenishment pump (212) is connected between the outlet of the main pump (211) and the inlet of the electric heater (23).

9. The passive flow distribution method under hot conditions for the steady-state loop system according to claim 8, characterized in that: include: Acquiring the temperature of the test piece (11) in real time; When the temperature of the test piece (11) is higher than or lower than a preset temperature value, a design flow rate corresponding to the temperature of the test piece (11) is obtained, the opening of the solenoid valve (221) is adjusted according to the design flow rate, and the flow rate is monitored using a mass flow meter (222), wherein when the temperature of the test piece (11) is higher than the preset temperature value, the opening of the solenoid valve (221) increases, and when the temperature of the test piece (11) is lower than the preset temperature value, the opening of the solenoid valve (221) decreases.

10. The passive flow distribution method under hot working condition of the steady-state loop system according to claim 9, characterized in that: Before obtaining the temperature of the test piece (11), the method further comprises: Start the main pump (211) and the electric heater (23), and start the water supply pump (212) and the heat exchanger (24); Determine whether the pressure of the test pipeline (2) is stable. If not, start the water supply pump (212) to supply water until the pressure is stable and then turn off the water supply pump (212); If yes, set the frequency of the main pump (211) and obtain the temperature of the test piece (11).

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