Passive molten salt valve and methods of use comprising the same

Abstract

The application discloses a kind of non-active molten salt valve and the use method comprising it, including molten salt flow channel, the molten salt flow channel is used to communicate with the molten salt system's molten salt pipeline, the molten salt flow channel outer peripheral side is also provided with cooling part and heating part spaced apart with the cooling part, the non-active molten salt valve further includes heat storage part and heat preservation part, the heat preservation part is arranged on the outer peripheral side of the molten salt flow channel, the heat preservation part is used to wrap the molten salt flow channel, the cooling part, the heating part and the heat storage part, the heat storage part is away from the molten salt flow channel and the heat storage part is spaced apart with the heating part and the cooling part arrangement;When the non-active molten salt valve is in the second open valve state, the heating part opens or closes, the cooling part is closed, the heat storage part is configured to release heat to the molten salt flow channel, and the heating part and / or the heat storage part are used to melt the frozen molten salt in the molten salt flow channel and open the non-active molten salt valve.

Description

Technical Field

[0001] The present invention relates in particular to a passive molten salt valve and a method of using the same. Background Technology

[0002] In molten salt reactors and molten salt storage and transportation systems, passive molten salt valves are typically used as isolation devices. Currently, these valves mainly employ a cryo-plug opening and closing scheme. This involves creating a molten salt cryo-plug locally in the pipeline to cut off the medium, and then melting the cryo-plug by heating to restore connectivity. This method offers advantages such as the absence of moving mechanical parts and high sealing reliability.

[0003] In existing technologies, molten salt valves typically use an external cooling device to lower the pipe temperature, causing the molten salt to solidify and form a cryo-plug, thus isolating the media on both sides. An external heating device then melts the cryo-plug, reconnecting the pipeline. In emergency situations (such as a plant-wide power outage or abnormal system temperature rise), the cooling device stops operating, and the cryo-plug melts naturally using ambient or residual system heat, thus achieving passive valve opening.

[0004] However, existing technologies have the following limitations: First, the opening of passive molten salt valves in traditional molten salt reactors depends on the ambient temperature of the reactor compartment. Since the ambient temperature of the reactor compartment has an upper limit, the available external heat flux density is limited (heat flux density is positively correlated with temperature), resulting in a slow melting process of the cryoplug and difficulty in controlling the passive valve opening time. Second, when the ambient temperature is low or the heat dissipation conditions are strong, the melting time of the cryoplug may exceed the safety requirements, affecting the safety of the system. Third, the existing molten salt valves use a heating and cooling mutually exclusive operation mode for opening and closing. In accident conditions, relying solely on the ambient temperature to open the molten salt valve or the heating device to gradually increase the temperature at a low temperature makes it difficult to control the valve opening time, and it is also relatively long. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art in which the passive opening time of the molten salt valve is difficult to control and there are safety hazards, and to provide a passive molten salt valve and a method of using it.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] A passive molten salt valve includes a molten salt flow channel for communicating with a molten salt pipeline of a molten salt system. A cooling section and a heating section spaced apart from the cooling section are also provided on the outer periphery of the molten salt flow channel. The passive molten salt valve further includes a heat storage section and a heat insulation section. The heat insulation section is located on the outer periphery of the molten salt flow channel and is used to enclose the molten salt flow channel, the cooling section, the heating section, and the heat storage section. The heat storage section is located away from the molten salt flow channel and is spaced apart from the heating section and the cooling section.

[0008] When the passive molten salt valve is in the first closed state, the heating section is closed and the cooling section is open. The cooling section is used to solidify the molten salt in the molten salt channel, thereby closing the passive molten salt valve. When the passive molten salt valve is in the second closed state, the heating section and the cooling section are configured to be open simultaneously. The heat storage section is used to absorb the heat from the heating section, and the cooling section is used to solidify the molten salt in the molten salt channel, thereby closing the passive molten salt valve. When the passive molten salt valve is in the first closed state... When the valve is open, the heating section is on, the cooling section is closed, and the heat storage section is configured not to release heat. The heating section is used to melt the solidified molten salt in the molten salt channel and open the passive molten salt valve. When the passive molten salt valve is in the second open state, the heating section is on or off, the cooling section is off, and the heat storage section is configured to release heat into the molten salt channel. The heating section and / or the heat storage section are used to melt the solidified molten salt in the molten salt channel and open the passive molten salt valve.

[0009] In this solution, by setting up a heat storage section and an insulation section, in addition to the passive molten salt valve utilizing the cooling and heating sections in the first valve-opening state, the heat storage section absorbs heat from the heating section, and the insulation section concentrates heat to prevent heat from escaping to the external environment. This addresses emergency conditions (such as plant-wide power outages or abnormal system temperature rises) by rapidly releasing the absorbed heat from the heat storage section, increasing the melting rate of the molten salt solidified by the cooling section, and quickly opening the passive molten salt valve to achieve the second valve-opening state. Furthermore, the heat storage section absorbs the heat released by the heating section without releasing any heat, thus achieving... The second valve-closing state overcomes the problem of the passive valve opening time being difficult to control due to the natural melting of molten salt by ambient temperature. This allows the opening time of the passive molten salt valve to be adjusted according to the operating conditions. In case of an accident or loss of external power, the valve can be opened by releasing the stored heat from the heat storage section. Heating and cooling are controlled in a coordinated manner, breaking through the traditional mutually exclusive logic. While maintaining the cooling section to cool and solidify the molten salt to stabilize the valve closure, heat storage is completed, improving the safety of the molten salt system and avoiding the safety hazards of the passive molten salt valve in accident conditions.

[0010] Preferably, the heating element is sleeved on the outer periphery of the cooling element, and the heating element is a resistance heating structure and / or an electromagnetic heating structure.

[0011] In this solution, the above settings are used to enable the heating element to release heat.

[0012] Preferably, the heating section further includes a heating branch extending from the heating section to the outer surface of the molten salt flow channel. When the passive molten salt valve is in the second closed state, the heating section is configured not to release heat to the heating branch.

[0013] In this solution, by setting up a heating branch, compared to setting up a separate heating section and separating it from the molten salt flow channel to release radiant heat, the heating branch directly contacts the molten salt flow channel and heats the molten salt solidified by the cooling section in the molten salt flow channel by means of heat conduction, so that the solidified molten salt melts and realizes the opening of the passive molten salt valve.

[0014] Preferably, the passive molten salt valve further includes an emergency power supply, which is configured to be electrically connected to the heating unit when the passive molten salt valve is in a first open state or a second open state and the heating unit is de-energized.

[0015] In this solution, the above settings are configured so that when the heating unit needs to be turned on and the external power supply is lost during an accident, the heating unit can be connected using an emergency power supply. The heating unit and the heat storage unit work together to release more heat, thereby adjusting the valve opening time to make the valve opening time shorter and realizing the second valve opening state of the passive molten salt valve.

[0016] Preferably, the cooling section is sleeved on the outer periphery of the molten salt channel and fits against the outer surface of the molten salt channel. The cooling section has a cooling channel inside and an interface is provided on the cooling section. The cooling channel is filled with cooling medium through the interface.

[0017] In this solution, the above-mentioned configuration is used to cool and solidify the molten salt in the molten salt flow channel area covered by the cooling unit, forming a plug in the molten salt flow channel to achieve valve closure.

[0018] Preferably, the heat storage part is sleeved on the outer periphery of the heating part, and the heat storage part is made of one or more of high-temperature resistant metal materials, ceramic materials, or refractory materials.

[0019] In this scheme, the above settings enable the heat storage section to have a high specific heat capacity and high temperature resistance, and to quickly release enough heat when the heat storage section needs to release heat, thereby accelerating the melting of solidified molten salt and thus accelerating valve opening.

[0020] Preferably, the heat storage section further includes a heat storage branch extending from the heat storage section to the outer surface of the molten salt flow channel. When the passive molten salt valve is in the second closed state, the heat storage section is configured not to release heat to the heat storage branch; when the passive molten salt valve is in the second open state, the heat storage section is configured to release heat to the heat storage branch.

[0021] In this scheme, by setting up the above configuration, compared to setting up a separate heat storage section and setting it apart from the molten salt flow channel to release radiant heat, the heat storage branch is in direct contact with the molten salt flow channel, and heats the molten salt solidified by the cooling section in the molten salt flow channel by means of heat conduction, so that the solidified molten salt melts and realizes the passive molten salt valve to open quickly.

[0022] Preferably, when the heat storage section releases heat, the heat released by the heat storage section and received by the molten salt channel is not less than the heat used to melt the molten salt solidified in the area of ​​the molten salt channel covered by the cooling section.

[0023] In this solution, the above-mentioned settings ensure that the solidified molten salt in the cooling section can be completely melted, so that the molten salt flow channel can remain unobstructed, the molten salt in the molten salt pipeline can be quickly discharged, and the safety of the molten salt system can be maintained.

[0024] A method of using a passive molten salt valve, wherein the method of using the passive molten salt valve is implemented using the passive molten salt valve as described above, and the method of using the passive molten salt valve includes the following steps:

[0025] S10. The molten salt in the area covered by the cooling section is solidified by passing the molten salt flow channel through the cooling section, and the heating section is closed so that the passive molten salt valve is in the first closed state.

[0026] The molten salt flow channel is used to melt the solidified molten salt in the area covered by the cooling section through the heating section, and the cooling section is closed so that the passive molten salt valve is in the first open state;

[0027] S20. The molten salt in the area covered by the cooling section is solidified by passing the molten salt flow channel through the cooling section, and the heating section is turned on and the heat storage section is used to absorb the heat of the heating section, so that the passive molten salt valve is in the second closed state.

[0028] The molten salt flow channel melts the solidified molten salt in the area covered by the cooling section through the heating section and / or the heat storage section, and the cooling section is closed so that the passive molten salt valve is in the second open state.

[0029] In this solution, the passive molten salt valve can be opened and closed under normal operating conditions using the first on / off valve state. Simultaneously, to avoid safety risks caused by slow molten salt discharge during accident conditions, a heat storage unit and an insulation unit are used to enable the passive molten salt valve to have a second on / off valve state. During accident conditions, the valve opening logic, which originally relied on ambient temperature to open the passive molten salt valve, is adjusted to regulate the opening time, i.e., rapid valve opening. This breaks through the traditional mutually exclusive logic, maintaining the cooling unit to cool and solidify the molten salt for stable valve closure while simultaneously completing heat storage, improving the safety of the molten salt system and avoiding potential safety hazards associated with the passive molten salt valve during accident conditions.

[0030] Preferably, step S20 further includes the following step:

[0031] When the passive molten salt valve is in the first open state or the second open state and the heating unit is de-energized, the emergency power supply is electrically connected to the heating unit.

[0032] In this solution, the above settings are used to connect the heating unit to the emergency power supply when the external power supply to the heating unit is lost in an accident. The heating unit and the heat storage unit work together to release more heat, that is, to adjust the valve opening time to make the valve opening time shorter, thus realizing the second valve opening state of the passive molten salt valve.

[0033] The positive and progressive effects of this invention are as follows: By incorporating a heat storage section and a heat insulation section, in addition to the passive molten salt valve utilizing the cooling and heating sections in the first open / closed state, the heat storage section absorbs heat from the heating section, and the heat insulation section concentrates heat, preventing heat from dissipating to the external environment. This addresses emergency conditions (such as a plant-wide power outage or abnormal system temperature rise) by rapidly releasing the absorbed heat from the heat storage section, increasing the melting rate of the molten salt solidified by the cooling section, and quickly opening the passive molten salt valve to achieve a second open state. Furthermore, the heat storage section absorbs the heat released by the heating section without releasing any heat. The heat is used to achieve the second valve-closing state, overcoming the problem that the passive valve opening time is difficult to control due to the natural melting of molten salt by ambient temperature in molten salt valves. This allows the valve opening time of passive molten salt valves to be adjusted according to the working conditions. In case of an accident or loss of external power, the valve can be opened by releasing the stored heat in the heat storage section. Heating and cooling are controlled in a coordinated manner, breaking through the traditional mutually exclusive logic. While maintaining the cooling section to cool and solidify the molten salt to stabilize the valve closing, heat storage is completed, improving the safety of the molten salt system and avoiding the safety hazards of passive molten salt valves in accident conditions. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a passive molten salt valve according to a preferred embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram showing the temperature change of the solidified molten salt in the second valve-open state over time, according to a preferred embodiment of the present invention.

[0036] Figure 3 This is a flowchart illustrating the usage method of a passive molten salt valve according to a preferred embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] Molten Salt Channel 1

[0039] Cooling section 2

[0040] Heating section 3

[0041] Thermal storage section 4

[0042] Insulation section 5 Detailed Implementation

[0043] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0044] This embodiment provides a passive molten salt valve, specifically as follows: Figure 1 and Figure 2 As shown, the passive molten salt valve includes a molten salt flow channel 1, which is used to communicate with the molten salt pipeline (not shown in the figure) of the molten salt system. A cooling section 2 and a heating section 3 are also provided on the outer periphery of the molten salt flow channel 1 at intervals. The passive molten salt valve also includes a heat storage section 4 and a heat insulation section 5. The heat insulation section 5 is provided on the outer periphery of the molten salt flow channel 1 and is used to wrap the molten salt flow channel 1, the cooling section 2, the heating section 3 and the heat storage section 4. The heat storage section 4 is disposed away from the molten salt flow channel 1 and is spaced apart from the heating section 3 and the cooling section 2.

[0045] When the passive molten salt valve is in the first closed state, the heating section 3 is closed and the cooling section 2 is open. The cooling section 2 is used to solidify the molten salt in the molten salt channel 1, thereby closing the passive molten salt valve. When the passive molten salt valve is in the second closed state, the heating section 3 and the cooling section 2 are configured to be open simultaneously. The heat storage section 4 is used to absorb the heat from the heating section 3, and the cooling section 2 is used to solidify the molten salt in the molten salt channel 1, thereby closing the passive molten salt valve. When the passive molten salt valve is in the first open state, the heating section 3 is open and the cooling section 2 is closed. The heat storage section 4 is configured not to release heat. The heating section 3 is used to melt the solidified molten salt in the molten salt channel 1 and open the passive molten salt valve. When the passive molten salt valve is in the second open state, the heating section 3 is either open or closed, the cooling section 2 is closed, and the heat storage section 4 is configured to release heat to the molten salt channel 1. The heating section 3 and / or the heat storage section 4 are used to melt the solidified molten salt in the molten salt channel 1 and open the passive molten salt valve.

[0046] Specifically, the molten salt channel 1 is illustrated as a circular tube structure, but its shape is not limited. The molten salt channel 1 can be made of high-temperature resistant metal alloy materials available in the prior art, which will not be elaborated further here. The cooling section 2, heating section 3, and heat storage section 4 are all tubular structures, while the insulation section 5 is a cylindrical structure made of existing insulation materials, which will not be elaborated further here. The cooling section 2 is fitted onto the outer surface of the molten salt channel 1 and is used to absorb heat from inside the molten salt channel 1, causing the molten salt inside the molten salt channel 1 to solidify and form a plug. This plug is used to close the passive molten salt valve. The heating section 3 is fitted onto the outer periphery of the cooling section 2 and spaced apart from it. The heating section 3 generates heat and avoids directly heating the cooling section 2, which would affect the heat transfer to the molten salt channel 1. Heat is then radiated within the insulation section 5 to the outer periphery of the molten salt channel 1, allowing the molten salt channel 1 to absorb heat and melt the solidified molten salt. This melts the plug, thus opening the passive molten salt valve. This is a passive molten salt valve that uses the cooling section 2 and the heating section 3 to achieve the first valve opening and closing state. The insulation section 5 can be filled with a gaseous or liquid medium to achieve heat transfer.

[0047] Furthermore, in this embodiment, an additional heat storage section 4 is provided. The heat storage section 4 is sleeved on the outer periphery of the heating section 3 and spaced apart from the heating section 3. The heat storage section 4 is disposed inside the insulation section 5 and close to the inner wall of the insulation section 5, that is, away from the molten salt flow channel 1 and the cooling section 2. The insulation section 5 is used to accumulate heat and prevent heat from escaping to the external environment. The heat storage section 4 is configured to absorb part or all of the heat from the heating section 3 when the passive molten salt valve is in the second closed state. At this time, the heating section 3 and the cooling section 2 are opened at the same time. The cooling section 2 is used to solidify the molten salt in the molten salt flow channel 1 to close the passive molten salt valve. The heat generated by the heating section 3 will not escape to the molten salt flow channel 1 or will not affect the solidification of the molten salt, ensuring the reliability of closing the passive molten salt valve. This allows the heat storage section 4 to release heat to adjust the opening time of the passive molten salt valve when the passive molten salt valve is in the second open state.

[0048] like Figure 2 As shown, specifically, when the passive molten salt valve is in the second open state, i.e., under an accident condition (such as a plant-wide power outage or abnormal system temperature rise), the time of the accident condition is T1. The heat storage unit 4 rapidly releases the absorbed heat, increasing the melting rate of the molten salt solidified by the cooling unit 2, and quickly opens the passive molten salt valve, achieving the second open state. The time when the passive molten salt valve is fully open is T2, and the solidified molten salt temperature gradually increases from the initial low temperature to the melting point T. m The initial temperature of the thermal storage section 4 is T. hFurthermore, the heat storage section 4 absorbs the heat released by the heating section 3 without releasing any heat. The heat storage section 4 can be a metal with high specific heat capacity, as is currently available. It can absorb a large amount of heat and releases little heat before its heat release critical point. The effect of the solidified molten salt in the cooling section 2 is negligible, thus achieving the second valve-closing state. This overcomes the problem of the passive valve opening time being difficult to control due to the natural melting of molten salt by the ambient temperature. The opening time of the passive molten salt valve can be adjusted according to the operating conditions. In case of an accident or loss of external power, the valve can be opened by releasing the stored heat from the heat storage section 4. Based on the existing method of using heating and cooling to control the first valve state, this method breaks through the traditional mutually exclusive logic. It maintains the cooling section 2 to cool down and solidify the molten salt to stabilize the valve while completing heat storage, improving the safety of the molten salt system. This avoids the safety hazards caused by the slow melting of solidified molten salt and the inability of the molten salt in the system to be quickly discharged during accident conditions, which could lead to system overheating.

[0049] Understandably, when the passive molten salt valve is in the second open state, the heating unit 3 can be opened or closed. When the heating unit 3 is open, the heat storage unit 4 and the heating unit 3 work together to release more heat, further shortening the opening time of the passive molten salt valve. When the heat storage unit 4 is opened alone, the heat released by the heat storage unit 4 can also melt the solidified molten salt, and the opening time of the passive molten salt valve can also meet the requirements under accident conditions.

[0050] In this embodiment, FLiBe molten salt is used as an example, with a melting point of approximately 460°C. When the passive molten salt valve is in the second on / off state, the temperature range of the heat storage unit 4 is preferably higher than the melting point of the molten salt but not exceeding the upper limit of the material's allowable temperature, for example, 500°C to 800°C, to ensure sufficient thermal driving force to melt the molten salt under emergency conditions.

[0051] In other embodiments, the cross-sectional shape of the molten salt channel 1, cooling section 2, heating section 3, heat storage section 4, and heat preservation section 5 may be a rectangular structure or other irregular structure.

[0052] In this embodiment, the heating part 3 is sleeved on the outer periphery of the cooling part 2, and the heating part 3 is a resistance heating structure.

[0053] In other embodiments, the heating part 3 is an electromagnetic heating structure.

[0054] Specifically, both resistance heating and electromagnetic heating structures require an external power source (not shown in the figure) in the prior art. The heating element 3 is installed within the insulation element 5 via a connecting rod (not shown in the figure) or a bracket (not shown in the figure) and is spaced apart from the cooling element 2. By separately installing the heating element 3 and spaced apart from the molten salt channel 1, radiant heat is released, so that the heat generated by the heating element 3 is concentrated through the insulation element 5 and radiated to the area of ​​the molten salt channel 1 covered by the cooling element 2, thereby melting the solidified molten salt and realizing the opening of the passive molten salt valve.

[0055] Furthermore, in this embodiment, the heating section 3 also includes a heating branch (not shown in the figure), which extends from the heating section 3 to the outer surface of the molten salt channel 1. When the passive molten salt valve is in the second closed state, the heating section 3 is configured not to release heat to the heating branch.

[0056] Specifically, the heating branch can be made of a high-temperature resistant metal alloy. The heating branch is a rod, driven by a motor or other drive mechanism as used in existing technologies, to achieve contact between the heating branch and the outer surface of the molten salt channel 1 and with the heating part 3 itself. Further details are omitted here. When the passive molten salt valve is in the second closed state, the end of the heating branch that contacts the heating part 3 is disengaged from the heating part 3, so that the heating part 3 is configured not to release heat to the heating branch. When the passive molten salt valve is in the second open state and the heating part 3 is open and releasing heat, the drive mechanism brings both ends of the heating branch into contact with the heating part 3 and the outer surface of the molten salt channel 1 respectively. Compared to separately setting the heating part 3 and spaced apart from the molten salt channel 1 to release radiant heat, the heating branch directly contacts the molten salt channel 1, heating the molten salt solidified by the cooling part 2 within the molten salt channel 1 through heat conduction, thereby further increasing the melting rate of the solidified molten salt and achieving the opening of the passive molten salt valve.

[0057] In this embodiment, the passive molten salt valve also includes an emergency power supply (not shown in the figure). The emergency power supply is configured to be electrically connected to the heating unit 3 when the passive molten salt valve is in the first open state or the second open state and the heating unit 3 is de-energized.

[0058] Specifically, the emergency power supply can be a storage battery or a diesel generator as in the prior art. The emergency power supply is electrically connected to the heating part 3 through a wire (not shown in the figure). The wire passes through the insulation part 5 and realizes power transmission. In the event of an accident, that is, when the passive molten salt valve is in the second open state, the heating part 3 needs to be opened and the external power supply is lost, the emergency power supply is used to connect the heating part 3, so that the heating part 3 and the heat storage part 4 work together to release more heat, that is, adjust the valve opening time to make the valve opening time shorter, and realize the second open state of the passive molten salt valve.

[0059] In this embodiment, the cooling section 2 is sleeved on the outer periphery of the molten salt channel 1 and fits against the outer surface of the molten salt channel 1. The cooling section 2 has a cooling channel (not shown in the figure) and an interface (not shown in the figure) is provided on the cooling section 2. The cooling channel is filled with cooling medium through the interface.

[0060] Specifically, the cooling section 2 is a metal shell structure fitted onto and conforming to the outer surface of the molten salt channel 1. A cooling channel is formed inside the cooling section 2, and an interface is provided on the cooling section 2, which communicates with the cooling channel. Cooling medium is introduced into the cooling channel through the interface, thereby cooling and solidifying the molten salt in the area covered by the cooling section 2 within the molten salt channel 1, forming a plug in the molten salt channel 1 to achieve valve closure. The cooling medium can be a low-temperature gas such as air or nitrogen, or a liquid medium such as water or heat transfer oil, as is available in the prior art; further details are omitted here.

[0061] In this embodiment, the heat storage part 4 is sleeved on the outer periphery of the heating part 3, and the material of the heat storage part 4 is one or more of the following: high temperature resistant metal material, ceramic material or refractory material.

[0062] Specifically, the heat storage section 4 can be directly bonded to the inner wall of the insulation section 5, or it can be installed inside the insulation section 5 via a connecting rod (not shown in the figure) or a bracket (not shown in the figure) and kept at a distance from the heating section 3. The heat storage section 4 is preferably made of a material with high specific heat capacity and high temperature resistance, such as nickel-based alloys, alumina ceramics, or refractory bricks in the prior art, so that the heat storage section 4 has high specific heat capacity and high temperature resistance, and can quickly release enough heat when the heat storage section 4 needs to release heat, thereby accelerating the melting of the solidified molten salt, that is, accelerating the opening of the valve.

[0063] In this embodiment, the heat storage section 4 further includes a heat storage branch (not shown in the figure), which extends from the heat storage section 4 to the outer surface of the molten salt flow channel 1. When the passive molten salt valve is in the second closed state, the heat storage section 4 is configured not to release heat to the heat storage branch; when the passive molten salt valve is in the second open state, the heat storage section 4 is configured to release heat to the heat storage branch.

[0064] Specifically, the heat storage branch can be made of a high-temperature resistant metal alloy. The heat storage branch is a rod, which is driven by a motor or other drive mechanism in the prior art to achieve contact between the heat storage branch and the outer surface of the molten salt channel 1 and with the heat storage part 4 itself. Further details are omitted here. When the passive molten salt valve is in the second closed state, the end of the heat storage branch that contacts the heat storage part 4 is disengaged from the heat storage part 4, so that the heat storage part 4 is configured not to release heat to the heat storage branch. When the passive molten salt valve is in the second open state, the drive mechanism brings the two ends of the heat storage branch into contact with the heat storage part 4 and the outer surface of the molten salt channel 1 respectively. Compared to separately setting the heat storage part 3 and spaced apart from the molten salt channel 1 to release radiant heat, the heat storage branch directly contacts the molten salt channel 1, heating the molten salt solidified by the cooling part 2 in the molten salt channel 1 by heat conduction, thereby further increasing the melting rate of the solidified molten salt and achieving rapid opening of the passive molten salt valve.

[0065] In this embodiment, when the heat storage section 4 releases heat, the heat received by the molten salt channel 1 from the heat storage section 4 is not less than the heat used to melt the solidified molten salt in the area covered by the cooling section 2 within the molten salt channel 1. By limiting the heat release from the heat storage section 4, it is ensured that the solidified molten salt in the cooling section 2 can be completely melted, allowing the molten salt channel 1 to remain unobstructed, quickly discharging the molten salt from the molten salt pipeline, and maintaining the safety of the molten salt system.

[0066] In this embodiment, the formula for calculating the heat required for the solidified molten salt in the area covered by the cooling section 2 and the molten salt channel 1 to completely melt is: Q1 = m s ·c s ·(T m -T0) + m s ·L, where m s The mass of molten salt solidified within the area of ​​the molten salt flow channel 1 covered by the cooling section 2, in kg; c s T0 is the specific heat capacity of molten salt, expressed in J / kg·K; T0 is the initial temperature of the molten salt solidified within the area of ​​the molten salt flow channel 1 covered by cooling section 2, expressed in °C; T0 is the temperature of the molten salt solidified within this area. m is the melting point of the solidified molten salt in molten salt channel 1, in °C; L is the latent heat of fusion of the molten salt in molten salt channel 1, in J / kg.

[0067] Specifically, the melting time of the solidified molten salt is designed based on the heat capacity and initial temperature of the heat storage unit 4. The heat storage unit 4 must provide a total heat to the solidified molten salt that is not less than the heat required for the solidified molten salt to heat up to its melting point and completely melt. Preferably, the effective heat that the heat storage unit 4 can release should not be less than the total heat required for the solidified molten salt to heat up and undergo phase change. The heat required for the solidified molten salt mainly includes sensible heat and latent heat of phase change, i.e., the sensible heat used to heat the solidified molten salt to its melting point, and the latent heat used to complete the phase change process. By constructing a formula for calculating the heat required for the complete melting of the solidified molten salt, and substituting it into the mass, specific heat capacity, and initial temperature of the heat storage unit 4, its heat storage capacity can be calculated. By increasing the initial temperature of the heat storage unit 4, the heating rate of the solidified molten salt increases, and the corresponding opening time of the passive molten salt valve is shortened; conversely, the opening time is prolonged.

[0068] Furthermore, the formula for calculating the heat that the heat storage unit 4 can provide is: Q2 = m h ·c h ·(T h -T e ), where m h The mass of the thermal storage section is 4 kg; c h The specific heat capacity of the thermal storage section is 4, with units of J / kg·K; T h The initial temperature of thermal storage section 4 is expressed in °C (°C); T e The temperature is close to the melting point of the solidified molten salt, or determined based on the heat balance relationship of the molten salt system, and the unit is °C. The valve opening time is calculated using the formula: t = Q1 / Q3. Where: Q3 is the average heat transfer power of the solidified molten salt in the four directions of the heat storage section, in W, which depends on factors such as the heat conduction path, contact area, and temperature difference. In actual processes, the heat transfer power varies with the temperature difference, and the valve opening time calculation formula is an estimate.

[0069] When constructing the calculation formula, the following approximate relationship can be used: Q3 = k·A·(T) h -T s ) / δ. Where: k is the equivalent thermal conductivity, in units of W / m·K, and the equivalent parameters after thermal conduction, interfacial contact thermal resistance, and radiative heat transfer also need to be considered; A is the heat transfer area, in units of m². 2 δ represents the equivalent heat transfer thickness, which is the equivalent heat transfer path thickness between the heat storage section 4 and the molten salt flow channel 1 corresponding to the solidified molten salt. It includes the pipe wall thickness, the contact interface, and any possible gap layers, and is measured in meters (m). T s The average temperature of the solidified molten salt during the heat transfer process is expressed in °C. To ensure that the valve opens within the preset time tset, the following conditions must be met: Q2 ≥ Q1 and t ≤ tset. Preferably, the heat storage unit 4 should also maintain sufficient temperature difference driving force during the heat transfer process to ensure that the heat transfer rate meets the time design requirements.

[0070] This embodiment uses FLiBe as an example of molten salt, where the melting point of the molten salt is T. m =460℃; initial temperature T0=400℃; specific heat capacity c s ≈2400 J / kg·K; latent heat L≈456654 J / kg. Assume the volume of the solidified molten salt is 1.0 × 10⁻⁶ J / kg. -3 m 3 Its density is approximately 2000 kg / m³ 3 Then: m s ≈2 kg. The heat required for the complete melting of solidified molten salt is: Q1≈1.2×10 6 J. If the thermal storage unit 4 is made of metal, take m. h =100kg, c h =500 J / kg·K,T h =800℃, T e If the temperature is approximately 460℃, then Q2≈1.7×10 7 J. That is, Q2 is much larger than Q1, and the heat storage section 4 has sufficient heat storage capacity. Assuming the average heat transfer power is approximately Q3 = 5000W, then the valve opening time is approximately t ≈ 1.2 × 10⁻⁶. 6 / 5000≈240s. Furthermore, by adjusting the heat capacity and initial temperature of the thermal storage section 4, and by adjusting the heat transfer structure parameters, the opening time of the passive molten salt valve in the second open state can be on the order of minutes or even shorter, thus meeting the salt discharge requirements under different safety conditions. It should be noted that the above calculation method is based on an engineering approximation model constructed from existing technology. In practical applications, relevant parameters can be corrected by combining numerical simulation or experimental calibration. For cases with significant radiation or convection effects, the equivalent thermal conductivity can be corrected or a correction term can be introduced for expansion; however, this will not be elaborated upon further here.

[0071] like Figure 3 As shown, this embodiment also provides a method for using a passive molten salt valve. The method for using the passive molten salt valve is implemented using the aforementioned passive molten salt valve, and includes the following steps:

[0072] S10. The molten salt in the area covered by the cooling section 2 is solidified by passing the molten salt flow channel 1 through the cooling section 2, and the heating section 3 is closed so that the passive molten salt valve is in the first closed state.

[0073] The molten salt flow channel 1 melts the solidified molten salt in the area covered by the cooling section 2 through the heating section 3, and the cooling section 2 is closed so that the passive molten salt valve is in the first open state.

[0074] S20. The molten salt in the area covered by the cooling section 2 is solidified by passing the molten salt flow channel 1 through the cooling section 2, and the heating section 3 is turned on and the heat storage section 4 is used to absorb the heat of the heating section 3 so that the passive molten salt valve is in the second closed state.

[0075] The molten salt in the area covered by the cooling section 2 is melted by the heating section 3 and / or the heat storage section 4 through the molten salt channel 1, and the cooling section 2 is closed so that the passive molten salt valve is in the second open state.

[0076] Specifically, under normal operating conditions, the passive molten salt valve can be opened and closed using the first switching valve state. At the same time, to avoid safety risks caused by slow molten salt discharge under accident conditions, the heat storage unit 4 and the insulation unit 5 enable the passive molten salt valve to have a second switching valve state. Under accident conditions, the valve opening logic that originally used ambient temperature to open the passive molten salt valve is adjusted to achieve valve opening time adjustment, i.e., rapid valve opening. This breaks through the traditional mutually exclusive logic, and while maintaining the cooling unit 2 to cool and solidify the molten salt to stabilize valve closure, heat storage is completed, improving the safety level of the molten salt system and avoiding safety hazards of the passive molten salt valve under accident conditions.

[0077] In this embodiment, step S20 further includes the following step:

[0078] When the passive molten salt valve is in the first or second open state and the heating unit 3 is de-energized, the emergency power supply is electrically connected to the heating unit 3. In case of an accident, when the heating unit 3 needs to be opened and the external power supply is lost, the emergency power supply is used to turn on the heating unit 3. The heating unit 3 and the heat storage unit 4 work together to release more heat, thereby adjusting the valve opening time to make it shorter, thus realizing the second open state of the passive molten salt valve.

[0079] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A passive molten salt valve, the passive molten salt valve comprising a molten salt flow channel for communicating with a molten salt pipeline of a molten salt system, wherein a cooling section and a heating section spaced apart from the cooling section are further provided on the outer periphery of the molten salt flow channel, characterized in that, The passive molten salt valve further includes a heat storage section and a heat insulation section. The heat insulation section is disposed on the outer periphery of the molten salt flow channel. The heat insulation section is used to wrap the molten salt flow channel, the cooling section, the heating section and the heat storage section. The heat storage section is disposed away from the molten salt flow channel and is spaced apart from the heating section and the cooling section. When the passive molten salt valve is in the first closed state, the heating section is closed and the cooling section is open. The cooling section is used to solidify the molten salt in the molten salt channel, thereby closing the passive molten salt valve. When the passive molten salt valve is in the second closed state, the heating section and the cooling section are configured to be open simultaneously. The heat storage section is used to absorb the heat from the heating section, and the cooling section is used to solidify the molten salt in the molten salt channel, thereby closing the passive molten salt valve. When the passive molten salt valve is in the first closed state... When the valve is open, the heating section is on, the cooling section is closed, and the heat storage section is configured not to release heat. The heating section is used to melt the solidified molten salt in the molten salt channel and open the passive molten salt valve. When the passive molten salt valve is in the second open state, the heating section is on or off, the cooling section is off, and the heat storage section is configured to release heat into the molten salt channel. The heating section and / or the heat storage section are used to melt the solidified molten salt in the molten salt channel and open the passive molten salt valve.

2. The passive molten salt valve as described in claim 1, characterized in that, The heating element is sleeved on the outer periphery of the cooling element, and the heating element is a resistance heating structure and / or an electromagnetic heating structure.

3. The passive molten salt valve as described in claim 2, characterized in that, The heating section further includes a heating branch that extends from the heating section to the outer surface of the molten salt flow channel. When the passive molten salt valve is in the second closed state, the heating section is configured not to release heat to the heating branch.

4. The passive molten salt valve as described in claim 3, characterized in that, The passive molten salt valve also includes an emergency power supply, which is configured to be electrically connected to the heating unit when the passive molten salt valve is in a first open state or a second open state and the heating unit is de-energized.

5. The passive molten salt valve as described in claim 1, characterized in that, The cooling section is sleeved on the outer periphery of the molten salt flow channel and fits against the outer surface of the molten salt flow channel. The cooling section has a cooling flow channel inside and an interface is provided on the cooling section. The cooling flow channel is filled with cooling medium through the interface.

6. The passive molten salt valve as described in claim 1, characterized in that, The heat storage part is sleeved on the outer periphery of the heating part, and the heat storage part is made of one or more of the following materials: high-temperature resistant metal material, ceramic material, or refractory material.

7. The passive molten salt valve as described in claim 6, characterized in that, The heat storage unit also includes a heat storage branch that extends from the heat storage unit to the outer surface of the molten salt flow channel. When the passive molten salt valve is in the second closed state, the heat storage unit is configured not to release heat to the heat storage branch; when the passive molten salt valve is in the second open state, the heat storage unit is configured to release heat to the heat storage branch.

8. The passive molten salt valve as described in claim 7, characterized in that, When the heat storage section releases heat, the heat released by the heat storage section and received by the molten salt channel is not less than the heat used to melt the solidified molten salt in the area of ​​the molten salt channel covered by the cooling section.

9. A method of using a passive molten salt valve, wherein the method of using the passive molten salt valve is implemented using a passive molten salt valve as described in any one of claims 1-8, characterized in that, The method of using the passive molten salt valve includes the following steps: S10. The molten salt in the area covered by the cooling section is solidified by passing the molten salt flow channel through the cooling section, and the heating section is closed so that the passive molten salt valve is in the first closed state. The molten salt flow channel is used to melt the solidified molten salt in the area covered by the cooling section through the heating section, and the cooling section is closed so that the passive molten salt valve is in the first open state; S20. The molten salt in the area covered by the cooling section is solidified by passing the molten salt flow channel through the cooling section, and the heating section is turned on and the heat storage section is used to absorb the heat of the heating section, so that the passive molten salt valve is in the second closed state. The molten salt flow channel melts the solidified molten salt in the area covered by the cooling section through the heating section and / or the heat storage section, and the cooling section is closed so that the passive molten salt valve is in the second open state.

10. The method of using the passive molten salt valve as described in claim 9, characterized in that, Step S20 also includes the following steps: When the passive molten salt valve is in the first open state or the second open state and the heating unit is de-energized, the emergency power supply is electrically connected to the heating unit.

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