A heat exchanger with adjustable thermal resistance, a thermal resistance control system and a method of using the same

Abstract

The present invention discloses a heat exchanger with adjustable thermal resistance, a thermal resistance control system and a method of using the same, and relates to the technical field of heat exchangers, including a tube side medium inlet, a tube side medium outlet, a shell side medium inlet, a shell side medium outlet, an upper head, a lower head, an upper tube sheet, a lower tube sheet, a shell, a heat transfer tube, a bottom inlet and outlet of a heat transfer medium, and a top inlet and outlet of a heat transfer medium. The heat transfer tube adopts a double-layer heat transfer tube structure, and the double-layer heat transfer tube is an outer tube, a gap, and an inner tube from the outside to the inside. The gap of the double-layer heat transfer tube is filled with heat transfer media with a large difference in thermal conductivity according to the operating conditions of the heat exchanger. The heat exchanger body is externally connected to a simple small loop, that is, a thermal resistance control system, which can switch the heat transfer medium in the gap of the double-layer heat transfer tube according to the main loop operating conditions, thereby adjusting the thermal resistance of the heat transfer tube within a large range, and realizing online adjustment of the heat exchange capacity of the heat exchanger.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and in particular to a heat exchanger with adjustable thermal resistance, a thermal resistance control system and a use method thereof. Background Art

[0002] Shell and tube heat exchanger is a traditional heat exchanger that uses the wall of the tube bundle as the heat transfer surface, also known as shell and tube heat exchanger. Shell and tube heat exchanger has the advantages of simple structure, wide range of material selection, easy cleaning and replacement of heat transfer tubes, and adaptability to high temperature and high pressure conditions, and is widely used.

[0003] The heat exchange tubes of traditional shell and tube heat exchangers are all single-layer tube structures. Different working media are carried on the tube side and the shell side. Once the heat exchange tube breaks, the media on both sides will mix, which is dangerous. At the same time, if the temperature difference between the media on both sides of the tube shell is too large, the large thermal stress will seriously affect the heat exchanger structure. Moreover, the single-layer heat transfer tube has a fixed heat transfer area and heat transfer resistance. For working conditions with huge differences, a single heat exchanger is difficult to meet the needs and needs to be redesigned and manufactured, which consumes a lot of manpower and material resources.

[0004] Therefore, the current shell and tube heat exchanger is difficult to meet the heat exchange requirements of media under different working conditions, which makes the application scope of the heat exchanger relatively narrow and has certain risks. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the current shell and tube heat exchanger is difficult to meet the heat exchange requirements of media under different working conditions, which makes the application range of the heat exchanger relatively narrow and there is a certain risk. The purpose is to provide a heat exchanger with adjustable thermal resistance, a thermal resistance control system and a method of using the same, which solves the problem that the current shell and tube heat exchanger is difficult to meet the heat exchange requirements of media under different working conditions, which makes the application range of the heat exchanger relatively narrow and there is a certain risk.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present application provides a heat exchanger with adjustable thermal resistance, comprising a tube side medium inlet, a tube side medium outlet, a shell side medium inlet, a shell side medium outlet, an upper head, a lower head, an upper tube sheet, a lower tube sheet, a shell, a heat transfer tube, a bottom inlet and outlet of a heat conductive medium, and a top inlet and outlet of a heat conductive medium. The heat transfer tube is a double-layer heat transfer tube, and the double-layer heat transfer tube comprises an outer tube, a gap, and an inner tube from the outside to the inside, and the gap of the double-layer heat transfer tube is filled with a heat conductive medium according to the operating conditions of the heat exchanger.

[0008] The heat transfer tubes in the heat exchanger of the present application adopt a double-layer structure, which can achieve the heat exchange capacity of the heat exchanger matching with various working conditions with greatly different heat exchange power levels by adjusting the type and composition of the heat-conducting medium in the gap between the double-layer heat transfer tubes and combining the temperature and flow regulation of the medium on both sides of the tube shell.

[0009] The heat transfer tube adopts a double-layer heat transfer tube structure, with a certain gap between the inner and outer layers of the heat transfer tube. Different media can be filled according to the main circuit working conditions, so as to adjust the thermal resistance of the heat transfer tube within a large range and achieve a large adjustment of the heat exchange capacity of the heat exchanger. At the same time, the high-temperature and high-pressure medium flows through the heat exchanger along the tube side, and the medium with lower temperature or pressure flows through the heat exchanger along the shell side, effectively reducing the thickness of the double-layer tube heat exchanger shell; the media on both sides of the tube shell flow in reverse, and the heat exchange is more sufficient.

[0010] The heat exchanger in the present application can realize flexible switching of the medium in the gap between the double-layer heat transfer tubes and online adjustment of the inert gas components, thereby realizing online adjustment of the heat exchange capacity of the double-layer heat exchanger.

[0011] Furthermore, the heat-conducting medium filled in the gap between the double-layer heat transfer tubes may be liquid metallic sodium or an inert gas.

[0012] Among them, the gap between the double-layer heat transfer tubes is filled with liquid metallic sodium under the conditions of high power level and small temperature difference between the two sides of the tube shell, which reduces the thermal resistance of the heat transfer tube and enhances the heat exchange capacity of the double-layer tube heat exchanger, matching the high power level of the system.

[0013] Among them, the gap between the double-layer heat transfer tubes is filled with inert gas under the conditions of low power level and large temperature difference between the two sides of the tube shell, which increases the thermal resistance of the heat transfer tube and reduces the heat exchange capacity of the double-layer tube heat exchanger to match the relatively low power level.

[0014] Among them, when liquid metallic sodium is used as the heat transfer medium, the top inlet and outlet of the heat transfer medium is the liquid metallic sodium outlet, and the bottom inlet and outlet of the heat transfer medium is the liquid metallic sodium inlet; when inert gas is used as the heat transfer medium, the top inlet and outlet of the heat transfer medium is the inert gas inlet, and the bottom inlet and outlet of the heat transfer medium is the inert gas outlet.

[0015] Furthermore, a gap connected to the top inlet and outlet of the heat-conducting medium is provided in the middle of the upper tube plate; a gap connected to the bottom inlet and outlet of the heat-conducting medium is provided in the middle of the lower tube plate.

[0016] The present application can effectively reduce the gas dead zone by setting a gap connected to the top inlet and outlet of the heat transfer medium in the middle of the upper tube plate and setting a gap connected to the bottom inlet and outlet of the heat transfer medium in the middle of the lower tube plate. When two inert gases are used to fill the gap between the double-layer heat transfer tubes, it can ensure that the two inert gases are evenly mixed to obtain the required thermal conductivity.

[0017] In a second aspect, the present application provides a thermal resistance control system, including the above-mentioned heat exchanger, and also including a pipe 1 connected to the bottom inlet and outlet of the heat transfer medium, and a pipe 2 connected to the top inlet and outlet of the heat transfer medium.

[0018] Furthermore, the pipeline one is connected to an isolation valve one, and the pipeline two is connected to an isolation valve two; the pipeline one and the pipeline two are both connected to a sodium storage tank, the pipeline one extends to the bottom of the sodium storage tank, and the outlet of the pipeline two is located at the top of the sodium storage tank.

[0019] Furthermore, a curved pipe is provided on the horizontal section of the second pipeline between the top inlet and outlet of the heat transfer medium and the second isolation valve.

[0020] By arranging a section of elbow pipe in the horizontal pipeline between the top inlet and outlet of the heat transfer medium and the second isolation valve, a certain buffer space can be reserved for the thermal expansion of the liquid metal sodium when the liquid metal sodium is used as the heat transfer medium, thereby avoiding excessive internal pressure caused by the thermal expansion of the liquid metal sodium in the gap between the double-layer heat transfer tubes, thereby improving the safety of equipment operation.

[0021] Furthermore, the top of the sodium storage tank is also connected to an air pipe, and the air pipe is connected to branch pipe one, branch pipe two and branch pipe three, branch pipe one is connected to a helium cylinder, branch pipe two is connected to an argon cylinder, and branch pipe three is connected to a vacuum system; branch pipe one is connected to a helium control valve, branch pipe two is connected to an argon control valve, and branch pipe three is connected to a vacuum control valve.

[0022] The inert gas composition can be adjusted online to adjust the heat transfer capacity of the double-layer heat exchanger. At the same time, if the temperature difference between the two sides of the tube shell is too large, the gap between the double-layer heat transfer tubes can be filled with inert gas to establish the temperature difference on both sides of the air gap, thereby reducing the thermal stress caused by the temperature difference between the inner and outer sides of the heat transfer tubes.

[0023] On the third aspect, the present application proposes a method for using a thermal resistance control system, which is used for working conditions where the power level is high and the temperature difference of the medium on both sides of the tube shell is small, and working conditions where the power level is low and the temperature difference of the medium on both sides of the tube shell is large; in the working condition where the power level is high and the temperature difference of the medium on both sides of the tube shell is small, liquid metal sodium is filled in the gap between the double-layer heat transfer tubes; in the working condition where the power level is low and the temperature difference of the medium on both sides of the tube shell is large, helium or a mixed gas of helium and argon is filled in the gap between the double-layer heat transfer tubes.

[0024] Furthermore, the specific operation method for the working conditions with high power level and small temperature difference of the medium on both sides of the tube shell is as follows: before filling the gap of the double-layer heat transfer tube with liquid metal sodium, all valves are in a closed state; open the isolation valve 1, the isolation valve 2 and the vacuum control valve, start the vacuum system, extract the gas in the cavity above the sodium storage tank, the pipeline and the gap of the double-layer heat transfer tube, then close the isolation valve 2 and the vacuum control valve, open the helium control valve, and fill the cavity above the sodium storage tank with helium through the helium bottle. At the same time, the liquid metal sodium in the sodium storage tank is pressed into the gap of the double-layer heat transfer tube through the isolation valve 1 along the pipeline 1 from the bottom inlet and outlet of the heat transfer medium under the action of helium pressure, then close the isolation valve 1 and the helium control valve, open the isolation valve 2 and the vacuum control valve, start the vacuum system to extract an appropriate amount of helium in the sodium storage tank, so that the sodium between the isolation valve 2 and the elbow is discharged under the action of gravity, so as to ensure that a certain space is left in the pipeline 2 to buffer the thermal expansion of sodium, and finally close the isolation valve 2 and the vacuum control valve to complete the filling of liquid sodium.

[0025] Furthermore, the specific operation method for the working conditions with low power level and large temperature difference of the medium on both sides of the tube shell is as follows: if there is liquid metallic sodium in the gap between the double-layer heat transfer tubes, the liquid metallic sodium needs to be discharged into the sodium storage tank first; before filling the gap between the double-layer heat transfer tubes with inert gas, all valves are in a closed state; open the vacuum valve, start the vacuum system to extract the inert gas in the sodium storage tank and the pipeline, then close the vacuum valve, open isolation valve 1 and isolation valve 2, so that the liquid metallic sodium is discharged from the sodium storage tank by itself under the action of gravity; then close isolation valve 1, open the helium control valve and the argon control valve, and fill inert gas into the cavity above the sodium storage tank and the pipeline 2 where the control valve 2 is located. The inert gas is filled into the gap between the double-layer heat transfer tubes along the pipeline through the isolation valve 2 and the top inlet and outlet of the heat transfer medium, and then close the isolation valve 2, the helium control valve and the argon control valve to complete the filling of the inert gas.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The double-layer tube heat exchanger with adjustable thermal resistance provided by the present invention adopts the main structure of the traditional fixed tube plate heat exchanger, and the main structure is compact. At the same time, the design of double-layer heat transfer tubes is adopted. By adjusting the type and composition of the heat transfer medium in the gap between the heat transfer tubes, the temperature and flow rate of the medium on both sides of the tube shell can be combined to achieve the heat exchange capacity of the heat exchanger matching with various working conditions with greatly different heat exchange power levels.

[0028] (2) The double-layer tube heat exchanger with adjustable thermal resistance provided by the present invention has a double-layer tube structure. A certain gap is left between the inner and outer layers of the tube. Different media can be filled according to the main circuit working conditions, thereby adjusting the thermal resistance of the tube within a relatively large range and achieving a large adjustment of the heat exchange capacity of the heat exchanger. At the same time, the high-temperature and high-pressure medium flows through the heat exchanger along the tube side, and the medium with lower temperature or pressure flows through the heat exchanger along the shell side, effectively reducing the outer shell thickness of the double-layer tube heat exchanger. The media on both sides of the tube shell flow in reverse, and the heat exchange is more sufficient.

[0029] (3) The double-layer heat exchanger with adjustable thermal resistance provided by the present invention has liquid metallic sodium filled in the gap between the double-layer heat transfer tubes under the working condition with high heat transfer capacity requirement, thereby reducing the thermal resistance of the heat transfer tubes and enhancing the heat transfer capacity of the double-layer heat exchanger, which matches the high power level of the system. In order to avoid the thermal expansion problem of the liquid metallic sodium in the gap between the double-layer heat transfer tubes, a section of elbow is arranged in the horizontal pipeline between the top inlet and outlet of the heat transfer medium and the second isolation valve, leaving a certain buffer space for the thermal expansion of the liquid metallic sodium.

[0030] (4) The double-layer heat exchanger with adjustable thermal resistance provided by the present invention is filled with inert gas in the gap between the double-layer heat transfer tubes under the condition of low power level and large temperature difference between the two sides of the tube shell, so as to increase the thermal resistance of the heat transfer tube and reduce the heat transfer capacity of the double-layer heat exchanger to match the relatively low power level; the inert gas composition can be adjusted online to adjust the heat transfer capacity of the double-layer heat exchanger; at the same time, in case of excessive temperature difference between the two sides of the tube shell, the temperature difference can be established on both sides of the air gap by filling the gap with inert gas, thereby reducing the thermal stress caused by the temperature difference on the heat transfer tubes on the inner and outer sides; a relatively narrow gap is left in the middle of the upper and lower tube sheets and connected to the inert gas inlet and outlet, which can effectively reduce the gas dead zone and enable the inert gas to be quickly and fully mixed to obtain the required gas thermal conductivity.

[0031] (5) The double-layer heat exchanger with adjustable thermal resistance provided by the present invention is provided with a system for switching between liquid metallic sodium and inert gas, which can realize flexible switching of the medium in the gap between the double-layer heat transfer tubes and online adjustment of the inert gas components, thereby realizing online adjustment of the heat exchange capacity of the double-layer heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0033] Figure 1 It is a structural schematic diagram of a thermal resistance control system in the present invention;

[0034] Figure 2 It is a front view of the main part of the heat exchanger in the present invention;

[0035] Figure 3 for Figure 2 Sectional view in the AA direction;

[0036] Figure 4 for Figure 3 Enlarged view of point B in the middle.

[0037] Marks and corresponding parts names in the attached drawings:

[0038] 1-tube side medium inlet, 2-tube side medium outlet, 3-shell side medium inlet, 4-shell side medium outlet, 5-upper head, 6-lower head, 7-upper tube sheet, 8-lower tube sheet, 9-shell, 10-heat transfer tube, 11-bottom inlet and outlet of heat transfer medium, 12-top inlet and outlet of heat transfer medium, 13-outer tube, 14-gap, 15-inner tube, 16-helium cylinder, 17-argon cylinder, 18-vacuum system, 19-sodium storage tank, V1-isolation valve one, V2-isolation valve two, V3-helium control valve, V4-argon control valve, V5-vacuum control valve. DETAILED DESCRIPTION

[0039] 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.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0042] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, a connection or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Example 1

[0044] like Figures 2 to 4 As shown, this embodiment provides a heat exchanger with adjustable thermal resistance, including a tube side medium inlet 1, a tube side medium outlet 2, a shell side medium inlet 3, a shell side medium outlet 4, an upper head 5, a lower head 6, an upper tube sheet 7, a lower tube sheet 8, a shell 9, a top inlet and outlet 12 of a heat transfer medium, a bottom inlet and outlet 11 of a heat transfer medium, and a heat transfer tube 10. The heat transfer tube 10 is a double-layer heat transfer tube 10. The double-layer heat transfer tube 10 comprises an outer tube 13, a gap 14, and an inner tube 15 from outside to inside. The gap 14 of the double-layer heat transfer tube 10 is filled with a heat transfer medium according to the operating conditions of the heat exchanger.

[0045] Specifically, the heat transfer medium filled in the gap 14 of the double-layer heat transfer tube 10 includes liquid metallic sodium or inert gas.

[0046] Among them, the gap 14 of the double-layer heat transfer tube 10 is filled with liquid metallic sodium under the working conditions of high power level and small temperature difference between the two sides of the tube shell, which reduces the thermal resistance of the heat transfer tube 10 and enhances the heat exchange capacity of the double-layer tube heat exchanger, matching the high power level of the system.

[0047] Among them, the gap 14 of the double-layer heat transfer tube 10 is filled with inert gas under the working conditions of low power level and large temperature difference between the two sides of the tube shell, so as to increase the thermal resistance of the heat transfer tube 10 and reduce the heat exchange capacity of the double-layer tube heat exchanger to match the relatively low power level.

[0048] Specifically, a gap connected to the top inlet and outlet 12 of the heat transfer medium is provided in the middle of the upper tube plate 7; and a gap connected to the bottom inlet and outlet 11 of the heat transfer medium is provided in the middle of the lower tube plate 8. By providing a gap 14 connected to the top inlet and outlet 12 of the heat transfer medium in the middle of the upper tube plate 7 and a gap connected to the bottom inlet and outlet 11 of the heat transfer medium in the middle of the lower tube plate 8, the gas dead zone can be effectively reduced. When two inert gases are used to fill the gap of the double-layer heat transfer tube 10, the two inert gases can be ensured to be evenly mixed to obtain the required thermal conductivity.

[0049] The heat transfer tube 10 in the heat exchanger adopts a double-layer structure, that is, by adjusting the type and component of the heat-conducting medium in the gap 14 of the double-layer heat transfer tube 10, the heat transfer capacity of the heat exchanger can be matched with various working conditions with large differences in heat transfer power levels in combination with the temperature and flow rate adjustment of the medium on both sides of the tube shell. At the same time, the heat transfer tube 10 adopts a double-layer heat transfer tube 10 structure, and a certain gap 14 is left between the outer tube 13 and the inner tube 15. Different media can be filled according to different main circuit working conditions, so as to adjust the thermal resistance of the heat transfer tube 10 in a large range and achieve a large adjustment of the heat transfer capacity of the heat exchanger; at the same time, the high-temperature and high-pressure medium flows through the heat exchanger along the tube side, and the medium with lower temperature or pressure flows through the heat exchanger along the shell side, which effectively reduces the thickness of the double-layer tube heat exchanger shell; the medium on both sides of the tube shell counterflows, and the heat exchange is more sufficient. The heat exchanger can also realize the flexible switching of the medium in the gap 14 of the double-layer heat transfer tube 10 and the online adjustment of the inert gas component, thereby realizing the online adjustment of the heat transfer capacity of the double-layer tube heat exchanger.

[0050] Example 2

[0051] Based on Example 1, Figures 1 to 4 As shown, this embodiment provides a thermal resistance control system, which, in addition to the heat exchanger in Embodiment 1, also includes a pipe 1 connected to the bottom inlet and outlet 11 of the heat-conducting medium, and a pipe 2 connected to the top inlet and outlet 12 of the heat-conducting medium; an isolation valve 1 V1 is connected to the pipe 1, and an isolation valve 2 V2 is connected to the pipe 2; the pipe 1 and the pipe 2 are both connected to the sodium storage tank 19, the pipe 1 extends to the bottom of the sodium storage tank 19, and the outlet of the pipe 2 is located at the top of the sodium storage tank 19.

[0052] Specifically, a section of elbow pipe is provided on the horizontal section of the second pipe between the top inlet and outlet 12 of the heat transfer medium and the second isolation valve V2. By providing a section of elbow pipe in the horizontal pipe between the top inlet and outlet 12 of the heat transfer medium and the second isolation valve V2, a certain buffer space can be reserved for the thermal expansion of the liquid metal sodium when the liquid metal sodium is used as the heat transfer medium, thereby avoiding excessive internal pressure caused by the thermal expansion of the liquid metal sodium in the gap 14 of the double-layer heat transfer pipe 10, and improving the safety of equipment operation.

[0053] Specifically, the top of the sodium storage tank 19 is also connected to a gas pipe, and the gas pipe is connected to branch pipes 1, 2 and 3. Branch pipe 1 is connected to the helium bottle 16, branch pipe 2 is connected to the argon bottle 17, and branch pipe 3 is connected to the vacuum system 18; branch pipe 1 is connected to the helium control valve V3, branch pipe 2 is connected to the argon control valve V4, and branch pipe 3 is connected to the vacuum control valve V5. The inert gas component can be adjusted online to adjust the heat exchange capacity of the double-layer heat exchanger. At the same time, if the temperature difference on both sides of the tube shell is too large, the gap 14 of the double-layer heat transfer tube 10 can be filled with inert gas to establish the temperature difference on both sides of the air gap, thereby reducing the thermal stress caused by the temperature difference on the inner and outer sides of the heat transfer tube 10.

[0054] The thermal resistance control system can be used for working conditions with high power level and small medium temperature difference on both sides of the tube shell, and can also be used for working conditions with low power level and large medium temperature difference on both sides of the tube shell. In the working conditions with high power level and small medium temperature difference on both sides of the tube shell, liquid metal sodium is filled into the gap 14 of the double-layer heat transfer tube 10; in the working conditions with low power level and large medium temperature difference on both sides of the tube shell, helium or a mixed gas of helium and argon is filled into the gap 14 of the double-layer heat transfer tube 10.

[0055] 1) The operation method of the thermal resistance control system for working conditions with high power level and small temperature difference of the medium on both sides of the tube shell is as follows: before filling the gap 14 of the double-layer heat transfer tube 10 with liquid metal sodium, all valves are in a closed state; open the isolation valve 1 V1, the isolation valve 2 V2 and the vacuum control valve V5, start the vacuum system 18, extract the gas in the cavity above the sodium storage tank 19, the pipeline and the gap 14 of the double-layer heat transfer tube 10, then close the isolation valve 2 V2 and the vacuum control valve V5, open the helium control valve V3, and fill the cavity above the sodium storage tank 19 with helium through the helium bottle 16. At the same time, the sodium storage tank Under the action of helium pressure, the liquid metallic sodium in 19 is pressed into the gap 14 of the double-layer heat transfer tube 10 through the isolation valve V1 along the pipeline 1 from the bottom inlet and outlet 11 of the heat transfer medium. Then, the isolation valve V1 and the helium control valve V3 are closed, the isolation valve V2 and the vacuum control valve V5 are opened, and the vacuum system 18 is started to extract a proper amount of helium in the sodium storage tank 19, so that the sodium between the isolation valve V2 and the elbow is discharged under the action of gravity, so as to ensure that a certain space is left in the pipeline 2 for buffering the thermal expansion of the sodium. Finally, the isolation valve V2 and the vacuum control valve V5 are closed to complete the filling of the liquid sodium.

[0056] 2) The specific operation method of the thermal resistance control system for working conditions with low power level and large temperature difference between the medium on both sides of the tube shell is as follows: if there is liquid metal sodium in the gap 14 of the double-layer heat transfer tube 10, the liquid metal sodium needs to be discharged into the sodium storage tank 19 first; before the inert gas is filled into the gap 14 of the double-layer heat transfer tube 10, all valves are in a closed state; open the vacuum valve, start the vacuum system 18 to extract the inert gas in the sodium storage tank 19 and the pipeline, then close the vacuum valve, open the isolation valve 1 V1 and the isolation valve 2 V2 2. Liquid metal sodium is discharged from the sodium storage tank 19 by gravity. Then the isolation valve 1 V1 is closed, the helium control valve V3 and the argon control valve V4 are opened, and inert gas is filled into the cavity above the sodium storage tank 19 and the pipe 2 where the control valve 2 is located. The inert gas flows along the pipe through the isolation valve 2 V2 and the top inlet and outlet 12 of the heat transfer medium into the gap 14 of the double-layer heat transfer pipe 10. Then the isolation valve 2 V2, the helium control valve V3 and the argon control valve V4 are closed to complete the filling of the inert gas.

[0057] The thermal resistance control system can realize flexible switching of the medium in the gap 14 of the double-layer heat transfer tube 10 and online adjustment of the inert gas component by setting up a device for switching between liquid metal sodium and inert gas, thereby realizing online adjustment of the heat exchange capacity of the double-layer tube heat exchanger.

[0058] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for using a thermal resistance control system, characterized in that: The thermal resistance control system comprises a heat exchanger, wherein the heat exchanger comprises a tube side medium inlet (1), a tube side medium outlet (2), a shell side medium inlet (3), a shell side medium outlet (4), an upper head (5), a lower head (6), an upper tube sheet (7), a lower tube sheet (8), a shell (9), a heat transfer tube (10), a bottom inlet and outlet (11) of a heat transfer medium, and a top inlet and outlet (12) of a heat transfer medium, and is characterized in that the heat transfer tube (10) is a double-layer heat transfer tube (10), and the double-layer heat transfer tube (10) comprises an outer tube (13), a gap (14), and an inner tube (15) from the outside to the inside, and the gap (14) of the double-layer heat transfer tube (10) is filled with a heat transfer medium according to the operating conditions of the heat exchanger; It also includes a pipe 1 connected to the bottom inlet and outlet (11) of the heat-conducting medium, and a pipe 2 connected to the top inlet and outlet (12) of the heat-conducting medium; The thermal resistance control system is used in working conditions where the power level is high and the temperature difference between the medium on both sides of the tube shell is small, and working conditions where the power level is low and the temperature difference between the medium on both sides of the tube shell is large; in working conditions where the power level is high and the temperature difference between the medium on both sides of the tube shell is small, the gap (14) of the double-layer heat transfer tube (10) is filled with liquid metal sodium; in working conditions where the power level is low and the temperature difference between the medium on both sides of the tube shell is large, the gap (14) of the double-layer heat transfer tube (10) is filled with helium or a mixed gas of helium and argon; The specific operation method for the working condition of low power level and large temperature difference of the medium on both sides of the tube shell is as follows: if there is liquid metal sodium in the gap (14) of the double-layer heat transfer tube (10), it is necessary to discharge the liquid metal sodium into the sodium storage tank (19); before filling the gap (14) of the double-layer heat transfer tube (10), all valves are in a closed state; open the vacuum valve, start the vacuum system (18) to extract the inert gas in the sodium storage tank (19) and the pipeline, then close the vacuum valve, open the isolation valve 1 (V1) and the isolation valve 2 (V2), so that the liquid metal sodium is in Under the action of gravity, the gas is discharged into the sodium storage tank (19) by itself; then the isolation valve 1 (V1) is closed, the helium control valve (V3) and the argon control valve (V4) are opened, and the inert gas is filled into the cavity above the sodium storage tank (19) and the pipeline 2 where the isolation valve 2 (V2) is located. The inert gas flows along the pipeline through the isolation valve 2 (V2) and the top inlet and outlet (12) of the heat transfer medium into the gap (14) of the double-layer heat transfer pipe (10), and then the isolation valve 2 (V2), the helium control valve (V3) and the argon control valve (V4) are closed to complete the filling of the inert gas.

2. The method for using a thermal resistance control system according to claim 1, characterized in that: The specific operation method for the working condition of high power level and small temperature difference of medium on both sides of the tube shell is as follows: before filling the gap (14) of the double-layer heat transfer tube (10) with liquid metal sodium, all valves are in a closed state; the isolation valve 1 (V1), the isolation valve 2 (V2) and the vacuum control valve (V5) are opened, the vacuum system (18) is started, and the gas in the cavity above the sodium storage tank (19), the pipeline and the gap (14) of the double-layer heat transfer tube (10) is extracted, and then the isolation valve 2 (V2) and the vacuum control valve (V5) are closed, and the helium control valve (V3) is opened, and helium is filled into the cavity above the sodium storage tank (19) through the helium bottle (16), and at the same time, the gas in the sodium storage tank (19) is Under the action of helium pressure, the liquid metal sodium is pressed into the gap (14) of the double-layer heat transfer tube (10) through the isolation valve 1 (V1) along the pipeline 1 from the bottom inlet and outlet (11) of the heat transfer medium. Then, the isolation valve 1 (V1) and the helium control valve (V3) are closed, the isolation valve 2 (V2) and the vacuum control valve (V5) are opened, and the vacuum system (18) is started to extract a proper amount of helium from the sodium storage tank (19), so that the sodium between the isolation valve 2 (V2) and the elbow is discharged under the action of gravity, so as to ensure that a certain space is left in the pipeline 2 for buffering the thermal expansion of the sodium. Finally, the isolation valve 2 (V2) and the vacuum control valve (V5) are closed to complete the filling of the liquid metal sodium.

3. The method for using a thermal resistance control system according to claim 1, characterized in that: The first pipeline is connected to an isolation valve 1 (V1), and the second pipeline is connected to an isolation valve 2 (V2); the first pipeline and the second pipeline are both connected to a sodium storage tank (19), the first pipeline extends to the bottom of the sodium storage tank (19), and the outlet of the second pipeline is located at the top of the sodium storage tank (19).

4. The method for using a thermal resistance control system according to claim 3, characterized in that: A curved pipe is arranged on the horizontal section of the second pipeline between the top inlet and outlet (12) of the heat-conducting medium and the second isolation valve (V2).

5. The method for using a thermal resistance control system according to claim 3, characterized in that: The top of the sodium storage tank (19) is also connected to a gas pipe, to which branch pipes 1, 2 and 3 are connected, wherein branch pipe 1 is connected to a helium cylinder (16), branch pipe 2 is connected to an argon cylinder (17), and branch pipe 3 is connected to a vacuum system (18); branch pipe 1 is connected to a helium control valve (V3), branch pipe 2 is connected to an argon control valve (V4), and branch pipe 3 is connected to a vacuum control valve (V5).

6. The method for using a thermal resistance control system according to claim 1, characterized in that: A gap connected to the top inlet and outlet (12) of the heat-conducting medium is provided in the middle of the upper tube plate (7); and a gap connected to the bottom inlet and outlet (11) of the heat-conducting medium is provided in the middle of the lower tube plate (8).

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