Molten salt heat storage heating device and molten salt heat storage device

Abstract

The invention relates to the technical field of fused salt heat storage, and provides a fused salt heat storage heating device which is suitable for being inserted into fused salt of the fused salt heat storage device in the vertical direction and comprises a heating pipe bundle which is integrally columnar and comprises at least one heating pipe. The part, inserted into the fused salt, of the heating tube bundle comprises a cold section and a heating section which are sequentially arranged in the depth direction of the fused salt, the cold section is far away from the insertion end of the heating tube bundle, the cold section does not have a heating function, and the heating section is used for heating the fused salt in the fused salt heat storage device. The temperature difference of the fused salt in the height direction in the fused salt heat storage device can be reduced, the temperature distribution uniformity of the fused salt is improved, and the utilization rate of the fused salt heat storage capacity is increased. The invention further provides a fused salt heat storage device.

Description

Technical Field

[0001] The present application relates to the technical field of molten salt heat storage, and in particular to a molten salt heat storage heating device and a molten salt heat storage device. Background Art

[0002] At present, there is a molten salt heat storage device, which includes a molten salt tank, an electric heating unit and a heat exchange pipe. The molten salt tank is filled with molten salt. The electric heating unit is inserted into the molten salt in the tank from the top of the molten salt tank. The entire length of the part of the electric heating unit inserted into the molten salt is a heating section (with a heating function). The heating section of the electric heating unit is used to heat the molten salt. The heat exchange pipe includes an inlet near the bottom of the molten salt tank and an outlet near the top of the molten salt tank. When the low-temperature fluid enters the heat exchange pipe from the inlet, it will exchange heat with the high-temperature molten salt in the tank through the heat exchange pipe, thereby converting the low-temperature fluid into a high-temperature and high-pressure fluid and discharging it from the outlet of the heat exchange pipe.

[0003] When the molten salt heat storage device releases heat, the water enters from the bottom and exits from the top. The heat exchange pipes are divided into preheating section, boiling section and superheating section from bottom to top. The heat transfer coefficient, heat transfer temperature difference and heat transfer amount of the preheating section + boiling section are significantly higher than those of the superheating section. Therefore, the temperature drop rate of the molten salt in the lower part of the molten salt tank is higher than that of the upper part. The overall temperature distribution of the molten salt in the tank is characterized by low temperature at the bottom and high temperature at the top. When the molten salt heat storage device is storing heat, if the entire length of the electric heating unit inserted into the molten salt is the heating section, it is easy to cause the electric heating unit to stop working when the upper molten salt in the tank is heated to the highest operating temperature. At this time, the temperature of the molten salt in the lower part of the tank is still relatively low, and the overall heat storage density of the molten salt in the tank is relatively low, and the heat storage capacity of the molten salt in the tank is not fully utilized. Summary of the invention

[0004] In order to solve the above problems, the present application provides a molten salt heat storage heating device and a molten salt heat storage device, which are cleverly designed and simple in structure. The present application can reduce the temperature difference of the molten salt in the height direction in the molten salt heat storage device, improve the uniformity of the molten salt temperature distribution, and improve the utilization rate of the molten salt heat storage capacity. The technical solutions adopted in the present application are as follows:

[0005] A molten salt heat storage and heating device, suitable for being inserted into the molten salt of a molten salt heat storage device in a vertical direction, comprising:

[0006] The heating tube bundle is columnar as a whole, and the heating tube bundle includes at least one heating tube. The portion of the heating tube bundle inserted into the molten salt includes a cold section and a heating section arranged in sequence along the depth direction of the molten salt. The cold section is far away from the insertion end of the heating tube bundle, and the cold section has no heating function. The heating section is used to heat the molten salt in the molten salt heat storage device.

[0007] By setting the portion of the heating tube bundle inserted into the molten salt as a cold section without heating function for the molten salt and a heating section with heating function for the molten salt, in other words, the portion of the heating tube bundle inserted into the molten salt does not have a heating function throughout its entire length, but the heating section is set at the lower part of the cold section to avoid heating the molten salt distributed along the height direction at the same time, thereby preventing the top molten salt (high-position molten salt) from reaching the shutdown temperature (a temperature within the molten salt heat storage temperature range and lower than the boiling point of the molten salt) too early, causing the heat storage system to shut down, while the molten salt at a lower position has not yet fully utilized its heat storage capacity. By using the heating section to preferentially heat the molten salt at a lower position, it is beneficial to improve the consistency of the temperature rise of the molten salt in the molten salt tank, make the temperature distribution of the molten salt in the height direction tend to be uniform, and improve the utilization rate of the molten salt heat storage capacity.

[0008] In some embodiments, the molten salt heat storage heating device also includes at least one baffle, which is installed in the heating section and / or at the junction of the cold section and the heating section. The outer edge of the baffle is arranged around the periphery of the heating tube bundle, and the baffle is used to slow down the convection of the molten salt on the upper and lower sides of the baffle.

[0009] By setting up the baffle, the thermal convection between the molten salt below the baffle and the molten salt above the baffle is slowed down, so as to prevent the molten salt at a high position in the molten salt tank from reaching the shutdown temperature too early, causing the heat storage system to shut down, while the molten salt at a low position has not yet fully utilized its heat storage capacity. The baffle improves the consistency of the temperature rise of the molten salt in the molten salt tank by slowing down the thermal convection of the upper and lower layers of molten salt, making the temperature distribution of the molten salt in the height direction tend to be uniform, and improving the utilization rate of the molten salt heat storage capacity.

[0010] In some embodiments, the baffle is provided with through holes corresponding to the heating tubes in the heating tube bundle, and the heating tubes are inserted into the through holes of the baffle, so that the baffle is connected with the heating tubes through insertion.

[0011] By arranging perforations on the baffle and forming an interlaced connection between the baffle and the heating tube through the perforations, on the one hand, the separation of the two sides of the entire cross-section of the heating tube bundle is achieved, thereby improving the effect of hindering the heat convection of the upper and lower layers of molten salt; on the other hand, the connection between the heating tubes in the heating tube bundle is improved, thereby improving the overall stability of the heating tube bundle.

[0012] In some embodiments, the baffle is in the shape of a flat plate, and a plate surface of the baffle is perpendicular to a length direction of the heating tube bundle.

[0013] In some embodiments, the baffle is provided with an outer edge inclined toward the insertion end of the heating tube bundle.

[0014] In some embodiments, there are a plurality of the baffles, one of the baffles is disposed at the junction of the cold section and the heating section, and a plurality of the baffles are spaced apart along the length direction of the heating section.

[0015] In some embodiments, the heating power of the heating section is evenly distributed along its length.

[0016] In some embodiments, the heating tube is U-shaped, and the heating tube includes a U-shaped sleeve, a heating wire, a lead-out rod and a thermally conductive insulating material. The two pipe openings of the U-shaped sleeve are each provided with the lead-out rod, and the two lead-out rods are inserted into the U-shaped sleeve with the same length. The heating wire is arranged in the U-shaped sleeve and the two ends of the heating wire are respectively connected to the corresponding ends of the lead-out rod. The U-shaped sleeve is filled with the thermally conductive insulating material. The portion of the heating tube corresponding to the lead-out rod forms the cold section of the heating tube bundle, and the portion of the heating tube corresponding to the heating wire forms the heating section of the heating tube bundle.

[0017] On the other hand, the present application provides a molten salt heat storage device, comprising: a molten salt tank, molten salt and the aforementioned molten salt heat storage and heating device, the molten salt is filled in the molten salt tank, and the molten salt heat storage and heating device is inserted in the molten salt along the vertical direction.

[0018] In some embodiments, the molten salt heat storage device also includes a plurality of oblique heat conductors arranged in the molten salt tank, the oblique heat conductors are arranged obliquely in the vertical direction, and the end of the oblique heat conductors close to the tank wall of the molten salt tank is lower; the oblique heat conductors are distributed in multiple layers along the height direction of the molten salt tank, and the plurality of oblique heat conductors in each layer are radially spaced around the axis of the molten salt tank; the oblique heat conductors are flat plates, and the plate surface of the oblique heat conductors is parallel to the axis of the molten salt tank.

[0019] The temperature of the upper molten salt near the axis is higher than that of the lower molten salt near the axis, and the temperature difference between the upper molten salt near the axis and the lower molten salt near the wall of the molten salt tank is greater than the temperature difference between the lower molten salt near the axis and the lower molten salt near the wall of the molten salt tank. By providing an oblique heat transfer member, the heat exchange efficiency between the molten salt near the axis and the molten salt near the wall of the molten salt tank is improved, so that more heat energy near the axis of the molten salt tank is transferred to the molten salt near the wall of the molten salt tank, thereby improving the heat release efficiency of the molten salt heat storage device.

[0020] The present application provides a molten salt heat storage heating device and a molten salt heat storage device, which have at least one of the following beneficial effects:

[0021] 1. The present application provides a molten salt heat storage heating device, which sets the portion of the heating tube bundle inserted into the molten salt as a cold section without heating function for the molten salt and a heating section with heating function for the molten salt. In other words, the portion of the heating tube bundle inserted into the molten salt does not have a heating function throughout its entire length, but the heating section is set at the lower part of the cold section to avoid heating the molten salt distributed in the height direction at the same time, thereby preventing the top molten salt (high-position molten salt) from reaching the shutdown temperature (a temperature within the molten salt heat storage temperature range and lower than the boiling point of the molten salt) too early, causing the heat storage system to shut down, while the molten salt at a lower position has not yet fully utilized its heat storage capacity. By using the heating section to preferentially heat the molten salt at a lower position, it is beneficial to improve the consistency of the temperature rise of the molten salt in the molten salt tank, make the temperature distribution of the molten salt in the height direction tend to be uniform, and improve the utilization rate of the molten salt heat storage capacity.

[0022] 2. The present application provides a molten salt heat storage and heating device, which slows down the heat convection between the molten salt below the baffle and the molten salt above the baffle by setting a baffle, so as to prevent the molten salt at a high position in the molten salt tank from reaching the shutdown temperature too early, causing the heat storage system to shut down, while the molten salt at a low position has not yet fully utilized its heat storage capacity. The baffle improves the consistency of the temperature rise of the molten salt in the molten salt tank by slowing down the heat convection of the upper and lower layers of molten salt, making the temperature distribution of the molten salt in the height direction tend to be uniform, and improving the utilization rate of the molten salt heat storage capacity.

[0023] 3. The present application provides a molten salt heat storage heating device, which, by setting a perforation on the baffle and forming an interlaced connection between the baffle and the heating tube through the perforation, achieves separation of both sides of the entire cross section of the heating tube bundle, thereby improving the effect of hindering heat convection between the upper and lower layers of molten salt, and, on the other hand, improves the connection between the heating tubes in the heating tube bundle, thereby improving the overall stability of the heating tube bundle.

[0024] 4. The present application provides a molten salt heat storage device, wherein the temperature of the upper molten salt near the axis is higher than that of the lower molten salt near the axis, and the temperature difference between the upper molten salt near the axis and the lower molten salt near the wall of the molten salt tank is greater than the temperature difference between the lower molten salt near the axis and the lower molten salt near the wall of the molten salt tank. By providing an oblique heat transfer member, the heat exchange efficiency between the molten salt near the axis and the molten salt near the wall of the molten salt tank is improved, so that more heat energy near the axis of the molten salt tank is transferred to the molten salt near the wall of the molten salt tank, thereby improving the heat release efficiency of the molten salt heat storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following will explain the preferred implementation mode in a clear and understandable manner in combination with the accompanying drawings, and further explain the above characteristics, technical features, advantages and implementation methods of a molten salt heat storage heating device and a molten salt heat storage device:

[0026] Figure 1It is the distribution diagram of the cold section and heating section of the heating tube bundle;

[0027] Figure 2 It is a schematic diagram of the structure in which the baffle is installed on the heating tube bundle;

[0028] Figure 3 is a schematic structural diagram of another embodiment of a spoiler;

[0029] Figure 4 is a schematic diagram of a molten salt heat storage device equipped with an oblique heat conducting member;

[0030] Figure 5 It is a comparison chart of the temperature cloud diagrams obtained by simulating the heating of molten salt using heating tube bundles with different heating section lengths;

[0031] Figure 6 It is a comparison chart of the temperature changes of molten salt at different depths obtained by simulating the heating of molten salt by heating tube bundles with different heating section lengths;

[0032] Figure 7 It is a comparison diagram of the temperature cloud diagrams obtained when three types of heating tube bundles are heated when the molten salt is heated: no baffle, baffle outer edge width 30mm and baffle outer edge width 200mm;

[0033] Figure 8 This is a comparison chart of the temperature changes of molten salt at different depths obtained when two heating tube bundles are used to heat molten salt, one without a flow blocker and the other with a flow blocker outer edge width of 30 mm.

[0034] Fig. 9 Schematic diagram of an embodiment in which the heating tube is spiral, wherein the pitch of the heating tube gradually decreases along the insertion direction of the heating tube.

[0035] Description of Figure Numbers:

[0036] Heating tube 1, baffle 2, U-shaped sleeve 3, electric heating wire 4, lead-out rod 5, molten salt tank 11, oblique heat conducting member 12, support member 13, base 14. DETAILED DESCRIPTION

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the specific implementation methods of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0038] In order to simplify the drawings, only the parts related to the present application are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0039] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0040] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0042] An existing molten salt heat storage device includes a molten salt tank, an electric heating unit and a heat exchange pipe. The molten salt tank is filled with molten salt. The electric heating unit is inserted into the molten salt in the tank from the top of the molten salt tank. The entire length of the part of the electric heating unit inserted into the molten salt is a heating section (with a heating function). The heating section of the electric heating unit is used to heat the molten salt. The heat exchange pipe includes an inlet near the bottom of the molten salt tank and an outlet near the top of the molten salt tank. When the low-temperature fluid enters the heat exchange pipe from the inlet, it will exchange heat with the high-temperature molten salt in the tank through the heat exchange pipe, thereby converting the low-temperature fluid into a high-temperature and high-pressure fluid and discharging it from the outlet of the heat exchange pipe.

[0043] When the above-mentioned molten salt heat storage device releases heat, the water enters from the bottom and exits from the top. The heat exchange pipes are preheating section, boiling section and superheating section from bottom to top. The heat transfer coefficient, heat transfer temperature difference and heat transfer amount of the preheating section + boiling section are significantly higher than those of the superheating section. Therefore, the temperature drop rate of the molten salt in the lower part of the molten salt tank is higher than that of the upper part. The overall temperature distribution of the molten salt in the tank is characterized by low temperature at the bottom and high temperature at the top. When the molten salt heat storage device is storing heat, if the entire length of the electric heating unit inserted into the molten salt is the heating section, it is easy to cause the upper molten salt in the tank to be heated to the highest operating temperature, triggering the protection mechanism of the heat storage system and controlling the electric heating unit to stop working. At this time, the temperature of the molten salt in the lower part of the tank is still relatively low, and the overall heat storage density of the molten salt in the tank is relatively low, and the heat storage capacity of the molten salt in the tank is not fully utilized.

[0044] To solve the above problems, the present application provides a molten salt heat storage heating device, which is suitable for being inserted into the molten salt of the molten salt heat storage device in a vertical direction, comprising: a heating tube bundle that is generally columnar, the heating tube bundle comprising at least one heating tube 1, the portion of the heating tube bundle inserted into the molten salt comprising a cold section (non-heating section) and a heating section sequentially arranged along the depth direction of the molten salt, the cold section being away from the insertion end of the heating tube bundle, the cold section having no heating function, and the heating section being used to heat the molten salt in the molten salt heat storage device.

[0045] In a specific embodiment, the heating tube bundle is formed by assembling a plurality of U-shaped heating tubes 1 (the assembly form is the prior art), referring to Figure 1 The U-shaped heating tube 1 includes a U-shaped sleeve 3, a heating wire 4, a lead-out rod 5 and a heat-conducting insulating material. The two pipe openings of the U-shaped sleeve 3 are each provided with the lead-out rod 5. The two lead-out rods 5 are inserted into the U-shaped sleeve 3 to the same length. The heating wire 4 is arranged in the U-shaped sleeve 3 and the two ends of the heating wire 4 are respectively connected to the corresponding ends of the lead-out rod 5. The U-shaped sleeve 3 is filled with the heat-conducting insulating material. The portion of the heating tube 1 corresponding to the lead-out rod 5 forms the cold section of the heating tube bundle, and the portion of the heating tube 1 corresponding to the heating wire 4 forms the heating section of the heating tube bundle. It can be understood that the length of the cold section is the length of the lead-out rod 5 inserted into the U-shaped sleeve 3. By changing the length of the lead-out rod 5 inserted into the U-shaped sleeve 3, the length of the cold section on the heating tube bundle can be adjusted. In other embodiments, the heating tube can be of other shapes, such as Fig. 9 The spiral shape shown, the composition and internal structure of the spiral heating tube refer to Figure 1 The U-shaped heating tube 1 in.

[0046] In the above embodiment, the thermally conductive insulating material can be crystalline magnesium oxide powder or modified magnesium oxide powder. The U-shaped sleeve 3 and the spiral sleeve of the spiral heating tube can be seamless carbon steel tube, seamless titanium tube, seamless stainless steel tube, seamless copper tube, etc. The lead-out rod 5 can be stainless steel, iron-chromium-aluminum alloy or nickel-chromium alloy, etc.

[0047] refer to Figure 5 , Figure 6, the temperature cloud diagram of the molten salt obtained by heating the molten salt with heating tube bundles of 4 different heating section lengths was simulated. In the first model, the entire length of the portion of the heating tube bundle inserted into the molten salt is the heating section (length 2050mm), in the second model, the heating section length of the portion of the heating tube bundle inserted into the molten salt is 1366mm, accounting for 2 / 3, and the rest is the cold section length, in the third model, the heating section length of the portion of the heating tube bundle inserted into the molten salt is 1025mm, accounting for 1 / 2, and the rest is the cold section length, in the fourth model, the heating section length of the portion of the heating tube bundle inserted into the molten salt is 683mm, accounting for 1 / 3, and the rest is the cold section length. The total heating power of the heating section is the same among the four models, and the heating power of the heating section in each model is evenly distributed along its own length direction. Figure 5 It can be seen that for the same heating power, the closer the heating section is to the insertion end of the heating tube bundle, that is, the more the heating section is concentrated at the lower part of the molten salt, the more evenly the temperature distribution of the molten salt is, and the more fully the heat storage capacity of the molten salt is utilized. Figure 6 It can be seen that it takes about 1.29 hours for the molten salt in the first model to reach the maximum operating temperature (or shutdown temperature: a temperature within the molten salt heat storage temperature range and lower than the boiling point of the molten salt), and the time taken for the second model, the third model and the fourth model is 3.52 hours, 4.18 hours and 4.33 hours respectively. This shows that the lower the heating section is concentrated in the molten salt, the longer it takes for the molten salt to reach the maximum operating temperature. The power of the heating section is the same. It can be seen that the more heat the molten salt absorbs, the higher the utilization rate of the molten salt heat storage capacity.

[0048] The above simulation uses Ansys Fluent 2021R1 version, and the simulation adopts transient analysis. The solver type uses pressure basis, the physical model uses laminar model, and the gravity acceleration is considered. The simulation selects SIMPLE format as the algorithm for solving the coupled momentum equation. The momentum equation and turbulent kinetic energy in the spatial control volume are discretized using the second-order upwind format, and the transient term is discretized by the first-order implicit algorithm. The Gauss-Seidel successive sub-relaxation algorithm is used to process the iterative algebraic equations, and the corresponding relaxation factors of pressure, momentum and density are 0.3, 0.7 and 1, respectively. The mesh is divided by unstructured swept mesh, and the heating bundle is locally encrypted. The final number of grids is about two million. Boundary conditions: The upper and lower surfaces and outer walls of the molten salt are all insulated, the heat flux density boundary is used in the heating bundle area, and the front and rear sides of the model are set as symmetric boundaries.

[0049] From the above, it can be seen that by setting the portion of the heating tube bundle inserted into the molten salt as a cold section without heating function for the molten salt and a heating section with heating function for the molten salt, in other words, the portion of the heating tube bundle inserted into the molten salt does not have a heating function throughout its entire length, but the heating section is set at the lower part of the cold section to avoid heating the molten salt distributed along the height direction at the same time, thereby avoiding the top molten salt (high-position molten salt) from reaching the shutdown temperature (a temperature within the molten salt heat storage temperature range and lower than the boiling point of the molten salt) too early, causing the heat storage system to shut down, while the molten salt at a low position has not yet fully utilized its heat storage capacity. By using the heating section to preferentially heat the molten salt at a low position, it is beneficial to improve the consistency of the temperature rise of the molten salt in the molten salt tank, make the temperature distribution of the molten salt in the height direction tend to be uniform, and improve the utilization rate of the molten salt heat storage capacity.

[0050] In one embodiment, the heating power of the heating section is evenly distributed along its length, which can reduce the specifications of the heating tube, facilitate the mass production of the heating tube, and save the manufacturing cost of the heating tube bundle. In other embodiments, the heating power of the heating section may not be evenly distributed along the length, for example, the heating power of the heating section gradually decreases from the insertion end of the heating tube bundle to the direction away from the insertion end.

[0051] In one embodiment, reference Figure 2 , Figure 3 The molten salt heat storage heating device also includes at least one baffle 2, which is installed in the heating section and / or at the junction of the cold section and the heating section. The outer edge of the baffle 2 is arranged around the periphery of the heating tube bundle, and the baffle 2 is used to slow down the convection of the molten salt on the upper and lower sides of the baffle 2.

[0052] In a specific embodiment, reference Figure 2 The baffle 2 is in the shape of a flat plate, which is convenient for processing and manufacturing. The plate surface of the baffle 2 is perpendicular to the length direction of the heating tube bundle. Figure 3 , the baffle 2 is provided with an outer edge inclined toward the insertion end of the heating tube bundle. This solution has a better effect of slowing down the thermal convection between the molten salt below the baffle 2 and the molten salt above the baffle. In addition to the structural shape of the baffle 2 affecting the effect of the baffle 2 in slowing down the thermal convection, in fact, the thickness of the baffle 2 and the outer edge size of the baffle 2 will also affect the effect of the baffle 2 in slowing down the thermal convection. In theory, increasing the thickness of the baffle 2 and increasing the outer edge size of the baffle 2 within a reasonable range can enhance the effect of the baffle 2 in slowing down the thermal convection, but when increasing the outer edge size of the baffle 2, the impact on the molten salt heat storage heating device should be avoided.

[0053] In one embodiment, there are multiple flow-blocking members 2, one of which is disposed at the junction of the cold section and the heating section, and multiple flow-blocking members 2 are spaced apart along the length direction of the heating section. Figure 7For the embodiment in which the baffle 2 is a flat plate, the temperature cloud diagrams of the molten salt obtained by heating the molten salt with three heating tube bundles: no baffle, baffle outer edge width of 30mm and baffle outer edge width of 200mm. Figure A corresponds to the heating tube bundle without baffle, Figure B corresponds to the heating tube bundle with baffle outer edge width of 30mm, and Figure C corresponds to the heating tube bundle with baffle outer edge width of 200mm. The heating power of the three heating tube bundles is the same, and the heating section length is the same (1366mm, accounting for 2 / 3). The model corresponding to Figure A is the same as the second model in Figure 5. Figure 7 It can be seen that compared with not setting up the baffle, setting up the baffle can improve the uniformity of the temperature distribution during the lava heating process, and as the width of the outer edge of the baffle increases, the uniformity of the temperature distribution during the molten salt heating process becomes better.

[0054] refer to Figure 8 , showing Figure 7 Comparison of the temperature changes of molten salt at different depths obtained when two heating tube bundles are used to heat molten salt, one without a flow blocker and the other with a flow blocker outer edge width of 30 mm. Figure 8 The finless model shown in the figure is a model without a flow blocker, and the 30mm ring rib model is a model with a flow blocker outer edge width of 30mm. Figure 8 The finless model shown in Figure 7 The model corresponding to Figure A and Figure 5 The second model in the three models is the same. Figure 8 The ring rib 30mm model shown in Figure 7 The model corresponding to Figure B is the same as that of Figure 8 It can be seen that it takes about 3.52 hours for the molten salt in the finless model to reach the highest operating temperature, and it takes about 3.82 hours for the molten salt in the 30mm ring rib model to reach the highest operating temperature. This shows that the time required for the molten salt to reach the highest operating temperature is extended by setting the baffle. The power of the heating section in the two models is the same. It can be seen that the molten salt in the model with the baffle absorbs more heat, and the utilization rate of the molten salt heat storage capacity is higher.

[0055] refer to Figure 7 , Figure 8 It can be seen that by setting up the baffle, the thermal convection between the molten salt below the baffle and the molten salt above the baffle is slowed down, so as to prevent the molten salt at a high position in the molten salt tank from reaching the shutdown temperature too early, causing the heat storage system to shut down, while the molten salt at a low position has not yet fully utilized its heat storage capacity. The baffle improves the consistency of the temperature rise of the molten salt in the molten salt tank by slowing down the thermal convection of the upper and lower layers of molten salt, making the temperature distribution of the molten salt in the height direction tend to be uniform, and improving the utilization rate of the molten salt heat storage capacity.

[0056] In one embodiment, the baffle is provided with a perforation corresponding to the heating tube in the heating tube bundle, and the heating tube is inserted into the perforation of the baffle so that the baffle is connected to the heating tube by insertion. It can be understood that by providing perforations on the baffle and forming an insertion connection between the baffle and the heating tube through the perforations, on the one hand, the separation of the two sides of the entire cross-section of the heating tube bundle is achieved, thereby improving the effect of hindering the heat convection of the upper and lower layers of molten salt, and on the other hand, the connection between the heating tubes in the heating tube bundle is improved, thereby improving the overall stability of the heating tube bundle. In other embodiments, a large through hole is provided in the middle of the baffle, and the edge shape of the through hole is adapted to the peripheral shape of the heating tube bundle. The advantage of this is that the processing, manufacturing and installation of the baffle are convenient, and there is no need to consider the corresponding relationship between the perforations and the heating tube 1 as in the above embodiments.

[0057] On the other hand, the present application provides a molten salt heat storage device, comprising: a molten salt tank 11, molten salt and the aforementioned molten salt heat storage and heating device, wherein the molten salt is filled in the molten salt tank 11, and the molten salt heat storage and heating device is inserted into the molten salt in a vertical direction. The specific structure of the molten salt heat storage and heating device refers to the aforementioned embodiment. Since the present molten salt heat storage device adopts the technical solution of the aforementioned embodiment, it at least has the beneficial effects brought by the technical solution of the aforementioned embodiment, which will not be described one by one here.

[0058] refer to Figure 4 In one embodiment, the molten salt heat storage device further includes a plurality of oblique heat conducting members 12 arranged in the molten salt tank 11, wherein the oblique heat conducting members 12 are arranged obliquely in the vertical direction, and the end of the oblique heat conducting member 12 close to the tank wall of the molten salt tank 11 is lower; the oblique heat conducting members 12 are distributed in multiple layers along the height direction of the molten salt tank 11, and the plurality of oblique heat conducting members 12 in each layer are radially spaced around the axis of the molten salt tank 11; the oblique heat conducting member 12 is in the shape of a flat plate, and the plate surface of the oblique heat conducting member 12 is parallel to the axis of the molten salt tank 11.

[0059] Specifically, refer to Figure 4 The oblique heat conducting members 12 of each layer are fixed by the support members 13, and the support members 13 are fixed on the base 14 located at the bottom of the molten salt tank 11. The oblique heat conducting members 12 and the support members 13 are preferably fixed by snap connection, plug connection or bolt connection, and welding is avoided as much as possible, and the base 14 is directly placed on the bottom of the molten salt tank 11, and there is no mechanical connection and welding with the bottom of the tank, so that the damage to the original structure of the molten salt tank 11 can be avoided, and the stress concentration at the bottom of the molten salt tank 11 caused by the setting of the base 14 can be prevented.

[0060] It is easy to understand that the temperature of the upper molten salt near the axis of the molten salt tank 11 is higher than the temperature of the lower molten salt near the axis of the molten salt tank 11, and the temperature difference between the upper molten salt near the axis of the molten salt tank 11 and the lower molten salt near the wall of the molten salt tank 11 is greater than the temperature difference between the lower molten salt near the axis of the molten salt tank 11 and the lower molten salt near the wall of the molten salt tank 11. By setting the oblique heat conductor 12, the heat exchange efficiency between the molten salt near the axis of the molten salt tank 11 and the molten salt near the wall of the molten salt tank 11 is improved, so that more heat energy near the axis of the molten salt tank 11 is transferred to the molten salt near the wall of the molten salt tank 11, thereby improving the heat release efficiency of the molten salt heat storage device. The oblique heat conductor 12 is distributed in multiple layers along the height direction of the molten salt tank 11 and the oblique heat conductor 12 is designed to be flat, and the plate surface of the oblique heat conductor 12 is parallel to the axis of the molten salt tank 11, so that the adverse effect on the fluidity of the molten salt in the tank caused by the setting of the oblique heat conductor 12 can be reduced.

[0061] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A molten salt heat storage and heating device, suitable for being inserted into the molten salt of a molten salt heat storage device in a vertical direction, characterized in that: include: The heating tube bundle is columnar as a whole, and the heating tube bundle includes at least one heating tube. The portion of the heating tube bundle inserted into the molten salt includes a cold section and a heating section arranged in sequence along the depth direction of the molten salt. The cold section is far away from the insertion end of the heating tube bundle, and the cold section has no heating function. The heating section is used to heat the molten salt in the molten salt heat storage device.

2. A molten salt heat storage and heating device according to claim 1, characterized in that: It also includes at least one baffle, which is installed in the heating section and / or at the junction of the cold section and the heating section. The outer edge of the baffle is arranged around the periphery of the heating tube bundle, and the baffle is used to slow down the convection of the molten salt on the upper and lower sides of the baffle.

3. A molten salt heat storage heating device according to claim 2, characterized in that: The baffle is provided with through holes corresponding to the heating tubes in the heating tube bundle, and the heating tubes are inserted into the through holes of the baffle, so that the baffle is connected with the heating tubes through insertion.

4. A molten salt heat storage and heating device according to claim 2, characterized in that: The baffle is in the shape of a flat plate, and the plate surface of the baffle is perpendicular to the length direction of the heating tube bundle.

5. A molten salt heat storage and heating device according to claim 2, characterized in that: The baffle is provided with an outer edge inclined toward the insertion end of the heating tube bundle.

6. A molten salt heat storage and heating device according to claim 4, characterized in that: There are a plurality of the baffles, one of which is disposed at the junction of the cold section and the heating section, and a plurality of the baffles are spaced apart along the length direction of the heating section.

7. A molten salt heat storage and heating device according to any one of claims 1 to 6, characterized in that: The heating power of the heating section is evenly distributed along its own length direction.

8. A molten salt heat storage and heating device according to claim 7, characterized in that: The heating tube is U-shaped, and includes a U-shaped sleeve, a heating wire, a lead-out rod and a heat-conducting insulating material. The two pipe openings of the U-shaped sleeve are respectively provided with a lead-out rod, and the two lead-out rods are inserted into the U-shaped sleeve with the same length. The heating wire is arranged in the U-shaped sleeve and the two ends of the heating wire are respectively connected to the corresponding ends of the lead-out rod. The U-shaped sleeve is filled with the heat-conducting insulating material. The portion of the heating tube corresponding to the lead-out rod forms the cold section of the heating tube bundle, and the portion of the heating tube corresponding to the heating wire forms the heating section of the heating tube bundle.

9. A molten salt heat storage device, characterized in that: include: A molten salt tank, molten salt, and a molten salt heat storage and heating device as described in any one of claims 1 to 8, wherein the molten salt is filled in the molten salt tank, and the molten salt heat storage and heating device is inserted in the molten salt along a vertical direction.

10. A molten salt heat storage device according to claim 9, characterized in that: It also includes a plurality of oblique heat-conducting members arranged in the molten salt tank, wherein the oblique heat-conducting members are inclined in the vertical direction, and one end of the oblique heat-conducting members close to the tank wall of the molten salt tank is lower; the oblique heat-conducting members are distributed in multiple layers along the height direction of the molten salt tank, and a plurality of the oblique heat-conducting members in each layer are radially spaced around the axis of the molten salt tank; the oblique heat-conducting members are in the shape of a flat plate, and the plate surface of the oblique heat-conducting members is parallel to the axis of the molten salt tank.

Images