A molten salt storage tank, a molten salt energy storage system and a temperature control method thereof

Abstract

The invention discloses a molten salt storage tank, a molten salt energy storage system and a temperature control method thereof. The molten salt storage tank comprises a shell, a heat insulation layer arranged in the shell and a temperature control layer arranged outside the shell; the heat insulation layer comprises a first heat insulation layer arranged on the inner side of the shell and a second heat insulation layer arranged on the inner bottom of the shell, and the temperature control layer comprises a first temperature control layer arranged on the outer side of the shell and a second temperature control layer arranged on the bottom of the second heat insulation layer; the invention arranges a heat insulation layer inside the shell and a temperature control layer outside the shell, and controls at least part of the molten salt in the gap between the first heat insulation layer and the second heat insulation layer to solidify by adjusting the thickness of the heat insulation layer on the side, the wind speed of the first ventilation channel layer and the wind speed of the second ventilation channel layer, thereby playing a role of sealing the heat insulation layer, so that the molten salt will no longer flow to the outside, and thus the molten salt will not corrode the shell.

Description

Technical Field

[0001] The invention relates to a molten salt storage tank, a molten salt energy storage system and a temperature control method thereof. Background Art

[0002] With the widespread promotion of renewable energy, its own volatility or intermittent characteristics have led to a lack of good compatibility between renewable energy and the current power grid infrastructure, resulting in the problem of "abandoning wind and solar power". In the current construction of renewable energy, energy storage is generally required. Currently, the most commonly used solution is lithium battery energy storage, but due to its economic and safety issues, lithium battery energy storage has not yet been widely deployed in renewable energy. Another feasible technical solution is molten salt energy storage, and a demonstration supporting project (molten salt solar thermal power station) has been carried out in the construction of large wind and solar base projects. The current supporting ratio is generally around 10%.

[0003] At present, there are several main problems with molten salt energy storage:

[0004] (1) Technical difficulties of molten salt storage tanks: At present, the diameter of large-scale high-temperature molten salt storage tanks is generally 20-50 meters, the height is 12-15 meters, the operating temperature is 565℃, and the corresponding heat storage scale is 3-5GWh. As the heat storage scale continues to increase, the diameter of the storage tank needs to be further increased (the height is difficult to increase due to the limitation of the molten salt pump), and the corresponding tank wall thickness needs to be further increased, which makes the manufacturing difficulty of the storage tank further increased, and the reliability and risk of the equipment will also increase sharply. At present, there is no successful precedent for the construction and application of molten salt storage tanks on a larger scale.

[0005] (2) Technical difficulties of molten salt pumps: The molten salt pumps in molten salt energy storage generally adopt the technical solution of submerged long-axis pumps, which are installed in the molten salt energy storage. The molten salt in the tank is sucked in from the bottom suction port of the submerged long-axis pump and then pumped out through the top outlet pipe. This type of molten salt pump has the characteristics of long pump shaft, high operating temperature, large vibration, difficult maintenance, and low reliability. At present, the solution of setting up a backup pump is generally used to solve the problem of low reliability of molten salt pumps.

[0006] (3) Technical difficulties of molten salt medium: At present, nitrate is generally used as the medium in molten salt energy storage. Since nitrate is a hazardous chemical, its production, transportation and storage must be managed in accordance with hazardous chemicals, resulting in high costs and limited production. In addition, the maximum operating temperature of nitrate generally does not exceed 600°C (nitrate is easy to decompose after exceeding 600°C), which limits the upper limit of nitrate's operating temperature, making it impossible to further increase the heat storage and release temperature range (generally working at 290-565°C). Chloride salts, as energy storage media, can be used at temperatures as high as 1000°C and above, with high thermal energy utilization efficiency. However, since molten chloride salts are highly corrosive under high temperature conditions, higher requirements are placed on the corrosion resistance of metal storage tanks, and the oxygen content in the molten salt and the environment needs to be strictly controlled, which greatly increases the energy storage cost. Summary of the invention

[0007] The technical problem to be solved by the present invention is to solve the problem that the scale of molten salt heat storage is limited due to the difficulty and risk of manufacturing molten salt storage tanks in existing molten salt energy storage systems, and to provide a molten salt storage tank, a molten salt energy storage system and a temperature control method thereof. The molten salt energy storage system of the present invention arranges an insulating layer in the molten salt storage tank, so that the operating temperature of the tank shell can be reduced, and the requirements for the thickness of the shell and the corrosion resistance of the material are correspondingly reduced, so that the diameter of the tank can be increased, that is, the heat storage capacity of the tank can be increased.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] The present invention provides a molten salt storage tank, which comprises a shell, a heat insulation layer arranged inside the shell, and a temperature control layer arranged outside the shell;

[0010] The heat insulation layer comprises a first heat insulation layer arranged on the side of the shell and a second heat insulation layer arranged on the bottom of the shell;

[0011] The second heat insulation layer and the first heat insulation layer both include a plurality of heat insulation blocks, the plurality of heat insulation blocks are spliced ​​with each other, and there are assembly gaps between the heat insulation blocks;

[0012] The first heat insulation layer and the second heat insulation layer are both provided with temperature measuring components;

[0013] The temperature control layer includes a first temperature control layer arranged on the side of the shell and a second temperature control layer arranged on the bottom of the shell;

[0014] The first temperature control layer includes a first ventilation channel layer and / or a thermal insulation layer for heat exchange. When the first temperature control layer includes the first ventilation channel layer and the thermal insulation layer, the thermal insulation layer is arranged outside the first ventilation channel layer;

[0015] The second temperature control layer includes a second ventilation channel layer for heat exchange.

[0016] In the present invention, the solidification of at least part of the molten salt in the assembly gap between the first thermal insulation layer and the second thermal insulation layer is controlled by adjusting the thickness of the thermal insulation layer and / or the wind speed of the first ventilation channel layer and the wind speed of the second ventilation channel layer.

[0017] In the present invention, the shell can be a shell with a bottom wall or a shell without a bottom wall. When the shell is a shell without a bottom wall, the shell includes a top wall and a side wall, and the second thermal insulation layer is directly arranged on the second temperature control layer.

[0018] In the present invention, the first temperature control layer preferably includes a first ventilation channel layer for heat exchange and a heat preservation layer, and the heat preservation layer is arranged outside the first ventilation channel layer around the shell. More preferably, the heat preservation layer is provided with an air inlet and an air outlet for the first ventilation channel layer to communicate with the outside.

[0019] In the present invention, the first temperature control layer preferably includes a first ventilation channel layer for heat exchange.

[0020] In the present invention, the first ventilation channel layer is preferably an annular cavity arranged around the side wall of the shell.

[0021] In the present invention, when the first temperature control layer is a heat-insulating layer, part of the molten salt in the assembly gap of the heat-insulating layer close to the shell is solidified by adjusting the thickness of the heat-insulating layer.

[0022] In the present invention, the thermal insulation layer may be conventional thermal insulation cotton in the art.

[0023] In the present invention, the second temperature control layer preferably includes a heat-insulating support layer with supporting strength and a second ventilation channel layer arranged in the heat-insulating support layer.

[0024] The material of the thermal insulation support layer is a conventional thermal insulation material in the art, such as thermal insulation bricks, heavy castables or ceramsite.

[0025] In the present invention, the second ventilation channel layer is preferably a cylindrical channel that runs from one side of the second temperature control layer to the other side, and the axis of the cylindrical channel is perpendicular to the axis of the shell.

[0026] In the present invention, the second ventilation channel layer is preferably arranged at a middle position in the height direction of the second temperature control layer.

[0027] In the present invention, the temperature control layer may further include a third temperature control layer arranged on the top of the outer wall of the shell, and the third temperature control layer is the same as the first temperature control layer.

[0028] Among them, the thickness of the third temperature control layer is preferably the same as the thickness of the first temperature control layer. Specifically, the thickness of the first ventilation channel layer in the third temperature control layer is the same as the thickness of the first ventilation channel layer in the third temperature control layer, and the thickness of the thermal insulation layer in the third temperature control layer is the same as the thickness of the thermal insulation layer in the third temperature control layer.

[0029] Wherein, the third temperature control layer and the first temperature control layer are preferably connected to form an integrated structure.

[0030] In the present invention, preferably, the first thermal insulation layer and the second thermal insulation layer both include multiple thermal insulation layer units, each thermal insulation layer unit includes multiple thermal insulation blocks, the multiple thermal insulation blocks are spliced ​​with each other, and there are assembly gaps between the thermal insulation blocks.

[0031] The multiple layers of thermal insulation layer units in the first thermal insulation layer are preferably arranged layer by layer along the radial direction of the shell, and the multiple layers of thermal insulation layer units in the second thermal insulation layer are preferably arranged layer by layer along the axial direction of the shell.

[0032] In the present invention, preferably, at least two connecting holes are provided on the insulation block in the first insulation layer, and a plurality of connecting columns are also provided in the first insulation layer. The connecting holes of the upper and lower adjacent insulation blocks in each insulation layer unit in the first insulation layer are coaxially connected to the connecting columns. By providing the connecting holes and the connecting columns, the first insulation layer is fixed, avoiding the use of adhesives.

[0033] In the present invention, the heat insulation layer further includes a third heat insulation layer arranged on the inner top of the shell.

[0034] Preferably, the third thermal insulation layer is connected to the top of the shell through a hanging member, and the hanging member preferably includes a support plate and a connecting rod, one end of the connecting rod is connected to the support plate, and the other end is connected to the top of the shell, and the third thermal insulation layer is arranged on the support plate, and a hole for the connecting rod to pass through is arranged on the third thermal insulation layer along its thickness direction.

[0035] Preferably, the third heat-insulating layer comprises a plurality of heat-insulating layer units arranged layer by layer along the axial direction of the shell, each layer of the heat-insulating layer unit comprises a plurality of heat-insulating blocks, the plurality of heat-insulating blocks are spliced ​​with each other, and there are assembly gaps between the heat-insulating blocks;

[0036] In the present invention, in each thermal insulation layer, the number of thermal insulation layer units can be adjusted according to the thickness of the thermal insulation layer, for example, 3.

[0037] In the present invention, in each heat insulation layer, the assembly gaps in two adjacent heat insulation layer units are preferably staggered.

[0038] In the present invention, preferably, one end of the heat insulation block is provided with a groove, and the other end is provided with a protrusion, and the protrusion and the groove are matched. By providing such a mortise and tenon structure, the connection of the two ends of the heat insulation block is facilitated.

[0039] In the present invention, the shape of the insulation block can be a commonly used shape in the art that is easy to stack, such as a rectangle. Of course, the shape of the insulation block of the present invention is not limited to a rectangle, and can also be an equilateral hexagon or other polygon.

[0040] In the present invention, the material of the heat insulation block is a material having good compatibility with the molten salt, such as one or more of aluminum oxide, magnesium oxide, zirconium oxide, boron nitride and aluminum nitride. The heat insulation block is generally formed by sintering.

[0041] In the present invention, the assembly gap may be 2-5 mm.

[0042] In the present invention, the temperature measuring component in the first heat insulation layer and / or the temperature measuring component in the second heat insulation layer may be a temperature sensor, and the temperature sensor may be a thermocouple temperature sensor.

[0043] In the present invention, the temperature measuring components in the first heat insulation layer are preferably arranged in plurality at equal intervals along the axial direction of the shell.

[0044] In the present invention, the temperature measuring component in the first thermal insulation layer is preferably located at 1 / 4 to 3 / 4 of the thickness of the inner wall of the first thermal insulation layer, and more preferably located at half the thickness of the inner wall of the first thermal insulation layer, so as to ensure that at least half of the molten salt in the first thermal insulation layer is in solid state, thereby improving the sealing safety.

[0045] In the present invention, the temperature measuring components in the second heat insulation layer are preferably arranged in plurality at equal intervals along the radial direction of the shell.

[0046] In the present invention, the temperature measuring component in the second thermal insulation layer is preferably located at 1 / 4 to 3 / 4 of the thickness from the inner wall of the second thermal insulation layer, and more preferably located at half the thickness from the inner wall of the second thermal insulation layer, so as to ensure that at least half of the molten salt in the second thermal insulation layer is in a solid state, thereby improving the sealing safety.

[0047] In the present invention, the heat insulation layer preferably further comprises a third heat insulation layer arranged on the top of the inner wall of the shell, and the third heat insulation layer is connected to the top of the shell through a suspension member. The load of the third heat insulation layer acts on the top of the shell.

[0048] Wherein, the suspension member preferably includes a support plate and a connecting rod, one end of the connecting rod is connected to the support plate, and the other end is connected to the top of the shell, the third thermal insulation layer is arranged on the support plate, and the third thermal insulation layer is provided with a hole along its thickness direction for the connecting rod to pass through.

[0049] In the present invention, the thickness of the heat preservation layer and each heat insulating layer is related to the thermal conductivity of the respective materials and the type of molten salt.

[0050] In the present invention, the molten salt storage tank may also be provided with an inlet and an outlet, the inlet is used for the molten salt to flow in, and the outlet is used for the molten salt to flow out.

[0051] The inlet is preferably arranged at the top of the molten salt storage tank to reduce the impact of the opening on the side of the molten salt storage tank on the integrity of the molten salt storage tank. The outlet is preferably arranged at the bottom side of the molten salt storage tank.

[0052] In the present invention, the internal effective diameter and the internal effective height of the molten salt storage tank can be adjusted according to actual working conditions. For example, the internal effective diameter of the molten salt storage tank is 80m, and the internal effective height is 12.5m. The internal effective diameter refers to the diameter of the inner cavity formed by the insulation layer, and the internal effective height refers to the height of the inner cavity formed by the insulation layer.

[0053] In the present invention, the shell material is conventional in the art, such as a metal steel shell or a reinforced concrete shell.

[0054] The present invention also provides a temperature control method for a molten salt storage tank, which is used to control the temperature of the molten salt in the insulation layer of the molten salt energy storage system, and specifically includes:

[0055] The temperature is monitored in real time using the temperature measuring components in the first insulation layer and the second insulation layer. According to the monitored temperature, the thickness of the insulation layer and / or the wind speed of the first ventilation channel layer and the wind speed of the second ventilation channel layer are adjusted until the temperature monitored by the temperature measuring component is below the melting point of the molten salt.

[0056] In the present invention, the set threshold is preferably a temperature value 40~120°C lower than the melting point of the molten salt, and more preferably a temperature value 80~120°C lower than the melting point of the molten salt. If the controlled temperature is too low, the heat storage efficiency of the molten salt storage tank will deteriorate.

[0057] In the present invention, the molten salt may be a chloride salt. The chloride salt is generally a eutectic salt of NaCl, KCl, and MgCl2, and the melting point of the chloride salt is 390°C.

[0058] In the present invention, the wind speed in the first ventilation channel layer is preferably 0-20 m / s, for example 0-8 m / s or 0-5 m / s. If the temperature monitored by the temperature measuring component is initially below the melting point of the molten salt, the wind speed in the first ventilation channel layer is 0.

[0059] In the present invention, the wind speed in the second ventilation channel layer is preferably 0-20 m / s, for example 0-15 m / s. If the temperature monitored by the temperature measuring component is initially below the melting point of the molten salt, the wind speed in the second ventilation channel layer is 0.

[0060] In the present invention, the liquid level of the molten salt in the first molten salt pump tank is preferably 20-80% of the highest liquid level. The liquid level of the molten salt in the second molten salt pump tank is preferably 20-80% of the highest liquid level.

[0061] The present invention also provides a molten salt energy storage system, which includes: a first molten salt storage tank and a second molten salt storage tank, the first molten salt storage tank is used to carry low-temperature molten salt, the second molten salt storage tank is used to carry high-temperature molten salt, the first molten salt storage tank and the second molten salt storage tank are both the aforementioned molten salt storage tanks, the outlet of the first molten salt storage tank is connected to the inlet of the second molten salt storage tank, and the inlet of the first molten salt storage tank is connected to the outlet of the second molten salt storage tank.

[0062] In the present invention, the molten salt energy storage system also includes a first molten salt pump tank, a second molten salt pump tank, a heater and a heat exchanger; the first molten salt storage tank is used to carry low-temperature molten salt, and the second molten salt storage tank is used to carry high-temperature molten salt; molten salt pumps are provided in the first molten salt pump tank and the second molten salt pump tank; the first molten salt storage tank and the second molten salt storage tank are both provided with an inlet and an outlet, the first molten salt pump tank and the heater are sequentially arranged between the outlet of the first molten salt storage tank and the inlet of the second molten salt storage tank along the flow direction of the low-temperature molten salt, and the second molten salt pump tank and the heat exchanger are sequentially arranged between the outlet of the second molten salt storage tank and the inlet of the first molten salt storage tank along the flow direction of the high-temperature molten salt.

[0063] A salt discharge pipe is provided at the bottom of the first molten salt pump tank and / or the bottom of the second molten salt pump tank to discharge particulate matter generated by chemical reactions between the molten salt and the atmosphere and insulation materials in the system, thereby reducing damage to equipment such as pumps, pipes, heat exchangers, and heaters. A stop valve may also be provided on the salt discharge pipe to control the switch of the salt discharge pipe.

[0064] Among them, the low-temperature molten salt in the first molten salt storage tank is heated by the heater and stored in the second molten salt storage tank, and the molten salt in the second molten salt storage tank is cooled by heat exchange and stored in the first molten salt storage tank, thereby realizing the heat storage and release work process.

[0065] The low-temperature molten salt generally refers to a molten salt at 100-500°C, such as a molten salt at 450°C, and the high-temperature molten salt generally refers to a molten salt above 600°C, such as 800°C.

[0066] Preferably, the top of the first molten salt pump tank is located below the lowest liquid level of the first molten salt storage tank in the vertical direction, and the top of the second molten salt pump tank is located below the lowest liquid level of the second molten salt storage tank in the vertical direction, so that the molten salt in the first molten salt pump tank and the second molten salt pump tank flows to the first molten salt pump tank and the second molten salt pump tank by gravity.

[0067] The vertical distance between the top of the first molten salt pump tank and the lowest liquid level of the first molten salt storage tank is preferably more than 2 m.

[0068] Preferably, a molten salt regulating valve is provided between the first outlet and the inlet of the first molten salt pump tank, between the second outlet and the inlet of the second molten salt pump tank, between the outlet of the first molten salt pump tank and the heater, and between the outlet of the second molten salt pump tank and the heat exchanger. The molten salt regulating valve is used to adjust the flow rate between the molten salt storage tank and the pump tank so that the molten salt liquid in the pump tank is in a suitable range and the flow rate meets the system operation requirements.

[0069] Preferably, a flow meter is provided at one or more of the first outlet and the inlet of the first molten salt pump tank, the second outlet and the inlet of the second molten salt pump tank, the outlet of the first molten salt pump tank and the heater, and the outlet of the second molten salt pump tank and the heat exchanger to monitor the flow in the corresponding pipeline.

[0070] Wherein, one or more of the first molten salt storage tank, the second molten salt storage tank, the first molten salt pump tank and the second molten salt pump tank are preferably provided with a liquid level meter inside to monitor the liquid level of the molten salt in the tank.

[0071] Preferably, a thermometer is provided inside one or more of the first molten salt storage tank, the second molten salt storage tank, the first molten salt pump tank, and the second molten salt pump tank to monitor the temperature of the molten salt in the tank.

[0072] Wherein, the molten salt pump can be a short-axis cantilever pump to improve the reliability of the molten salt pump.

[0073] Preferably, the molten salt regulating valve, the heat exchanger, the heater, the first molten salt pump tank, the second molten salt pump tank and the outside of the pipeline in the molten salt energy storage system are all provided with a thermal insulation structure. It is used to maintain their temperature above the melting point of the molten salt to prevent the molten salt from solidifying. The thermal insulation structure preferably includes an electric heating layer and a thermal insulation layer outside the electric heating layer.

[0074] In the present invention, the molten salt energy storage system may further include a gas communicating pipe, the two ends of which are respectively connected to the first molten salt storage tank and the second molten salt storage tank, for automatically balancing the gas pressure above the molten salt in the first molten salt storage tank and the second molten salt storage tank, thereby reducing the use of inert gas and preventing heat loss.

[0075] Wherein, the diameter of the gas communication pipe can be 20~100mm.

[0076] In the present invention, the thickness of the thermal insulation layer in the second molten salt storage tank is generally greater than the thickness of the thermal insulation layer in the first molten salt storage tank.

[0077] In the present invention, the molten salt energy storage system may further include a temperature control system, and the temperature control system is used to control the wind speed of the first ventilation channel layer and the wind speed of the second ventilation channel layer according to the temperature monitored by the temperature measuring component.

[0078] The present invention also provides an operation method of the aforementioned molten salt energy storage system, which comprises the following steps:

[0079] During heat storage, the low-temperature molten salt in the first molten salt storage tank flows into the second molten salt storage tank after being heated;

[0080] When releasing heat, the high-temperature molten salt in the second molten salt storage tank flows into the second molten salt storage tank after heat exchange.

[0081] In the present invention, preferably, during heat storage, the low-temperature molten salt in the first molten salt storage tank enters the first molten salt pump tank by gravity, and is then transported to the heater through the molten salt pump in the first molten salt pump tank for heating and then flows into the second molten salt storage tank.

[0082] In the present invention, preferably, when releasing heat, the high-temperature molten salt in the second molten salt storage tank enters the second molten salt pump tank by gravity, and is then transported to the heat exchanger through the molten salt pump in the second molten salt pump tank for heat exchange and then flows into the first molten salt storage tank.

[0083] The positive and progressive effects of the present invention are:

[0084] (1) In the present invention, a heat insulating layer is provided inside the shell and a temperature control layer is provided outside the shell. By adjusting the thickness of the heat insulating layer on the side or the wind speed in the first ventilation channel layer and the wind speed in the second ventilation channel layer, at least part of the molten salt in the gap between the first heat insulating layer and the second heat insulating layer is controlled to solidify, thereby playing the role of sealing the heat insulating layer, so that the molten salt will no longer flow to the outside, and the molten salt will not corrode the shell; at the same time, the operating temperature of the shell is greatly reduced. After the operating temperature is reduced, the allowable stress of the shell material is greatly increased, which makes it possible to greatly increase the diameter of the storage tank, thereby increasing the heat storage capacity of the energy storage system (10-20GWh or more).

[0085] (2) Since the shell does not come into contact with the molten salt, the problem of shell corrosion is eliminated. In addition to conventional nitrates, the working medium in the molten salt energy storage system can further use chloride salt, which is cheap, has a high upper working temperature limit (wide heat storage and release temperature range), and is highly corrosive.

[0086] (3) The molten salt energy storage system of the present invention can also reduce the pump shaft length from more than 12-15 meters to less than 2-3 meters by setting an external molten salt pump tank, which is conducive to solving the shortcomings of the molten salt pump such as long pump shaft, large vibration, difficult maintenance, and low reliability. In actual engineering implementation, a short-axis cantilever pump technical solution can be adopted to further significantly improve the reliability of the molten salt pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 This is a schematic diagram of the structure of the molten salt storage tank described in Example 1 of the present invention.

[0088] Figure 2 This is a schematic diagram of the structure of the molten salt energy storage system described in Example 1 of the present invention.

[0089] Figure 3 This is a schematic diagram of the structure of the insulation block described in Example 1 of the present invention.

[0090] Description of Reference Numerals

[0091] The first molten salt storage tank 1

[0092] Housing 101

[0093] Insulation layer 102

[0094] The third insulation layer 1021

[0095] Second thermal insulation layer 1022

[0096] The first insulation layer 1023

[0097] Insulation block 1024

[0098] Groove 1025

[0099] Bump 1026

[0100] Connection hole 1027

[0101] Temperature control layer 103

[0102] Top insulation layer 1031

[0103] Side insulation layer 1032

[0104] Thermal insulation support layer 1033

[0105] First ventilation channel layer 1034

[0106] Second ventilation channel layer 1035

[0107] Air Inlet 1036

[0108] Air outlet 1037

[0109] Suspension 104

[0110] First Import 105

[0111] First Exit 106

[0112] Side temperature measuring component 107

[0113] Bottom temperature measuring component 108

[0114] Second molten salt storage tank 2

[0115] Second Import 201

[0116] Second Exit 202

[0117] First molten salt pump tank 3

[0118] Second molten salt pump tank 4

[0119] Molten salt pump 5

[0120] Heater 6

[0121] Heat exchanger 7

[0122] Molten salt regulating valve 8

[0123] Flow meter 9

[0124] Liquid level gauge 10

[0125] Thermometer 11

[0126] Salt discharge pipe 12

[0127] Stop valve 13

[0128] Gas communication pipe 14 DETAILED DESCRIPTION

[0129] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0130] Example 1

[0131] This embodiment discloses a molten salt energy storage system. Figure 1 and Figure 2 The invention comprises: a first molten salt storage tank 1, a second molten salt storage tank 2, a first molten salt pump tank 3, a second molten salt pump tank 4, a heater 6 and a heat exchanger 7. The first molten salt storage tank 1 is used to carry low-temperature molten salt, and the second molten salt storage tank 2 is used to carry high-temperature molten salt.

[0132] The first molten salt storage tank 1 includes a shell 101 , a heat insulating layer 102 arranged inside the shell 101 , and a temperature control layer arranged outside the shell.

[0133] The housing 101 is a metal steel housing without a bottom wall.

[0134] The thermal insulation layer 102 includes a first thermal insulation layer 1023 arranged on the inner side wall of the shell 101, a second thermal insulation layer 1022 arranged on the inner bottom of the shell 101 and a third thermal insulation layer 1021 arranged on the inner top wall of the shell 101, each thermal insulation layer includes a multi-layer thermal insulation layer unit, wherein the multi-layer thermal insulation layer units in the third thermal insulation layer 1021 and the second thermal insulation layer 1022 are arranged layer by layer along the axial direction of the shell 101, and the multi-layer thermal insulation layer units in the first thermal insulation layer 1023 are arranged layer by layer along the radial direction of the shell 101; each layer of the thermal insulation layer unit includes a plurality of thermal insulation blocks 1024, the thermal insulation blocks 1024 are in the shape of rectangular blocks, the plurality of thermal insulation blocks 1024 are spliced ​​with each other, there are assembly gaps between the thermal insulation blocks 1024, the assembly gaps are 2~5mm, and the gaps between the thermal insulation blocks 1024 in each two adjacent layers of the thermal insulation layer units are staggered.

[0135] like Figure 3 As shown, a groove 1025 is provided at one end of the heat insulating block 1024, and a protrusion 1026 is provided at the other end, the protrusion 1026 and the groove 1025 cooperate with each other, two connection holes 1027 are provided on the heat insulating block 1024, and a plurality of connection columns are also provided in the first heat insulating layer 1023, and the connection holes 1027 of the upper and lower adjacent heat insulating blocks 1024 in each heat insulating layer unit in the first heat insulating layer 1023 are coaxially connected to the connection column, one end of the connection column is fixed in the third heat insulating layer 1021, and the other end is fixed in the second heat insulating layer 1022. The heat insulating block 1024 is made of magnesium oxide brick.

[0136] The third thermal insulation layer 1021 is connected to the top of the shell 101 through the suspension member 104. The suspension member 104 includes a support plate and a connecting rod. One end of the connecting rod is connected to the support plate, and the other end is connected to the top of the shell 101. The third thermal insulation layer 1021 is arranged on the support plate. The third thermal insulation layer 1021 is provided with a hole along its thickness direction for the connecting rod to pass through.

[0137] The first heat insulation layer 1023 is provided with a side temperature measuring component 107, and the second heat insulation layer 1022 is provided with a bottom temperature measuring component 108. Both the side temperature measuring component 107 and the bottom temperature measuring component 108 are thermocouple temperature measuring instruments. The distance between the side temperature measuring component 107 and the inner wall of the shell 101 is half the thickness of the first heat insulation layer 1023, and the distance between the bottom temperature measuring component 108 and the upper surface of the heat insulation support layer 1033 is half the thickness of the second heat insulation layer 1022.

[0138] The temperature control layer includes a first temperature control layer arranged on the outer wall of the shell 101, a second temperature control layer arranged at the bottom of the second heat insulation layer 1022, and a third temperature control layer arranged on the outer top wall of the shell 101. The first temperature control layer includes a side insulation layer 1032 and a first ventilation channel layer 1034. The first ventilation channel layer 1034 is an annular cavity arranged around the side of the shell 101, and the annular cavity is sandwiched between the side insulation layer 1032 and the outer wall of the shell 101. The lower side of the side insulation layer 1032 is provided with an air inlet 1036 penetrating along the thickness direction thereof, and the upper side of the side insulation layer 1032 is provided with an air outlet 1037 penetrating along the thickness direction thereof, and the air inlet 1036 and the air outlet 1037 communicate the annular cavity with the outside.

[0139] The first temperature control layer is the same as the third temperature control layer. The third temperature control layer includes a top insulation layer 1031 and a first ventilation channel layer 1034. The first ventilation channel layer 1034 is an annular cavity arranged around the top of the shell, and the annular cavity is sandwiched between the top insulation layer 1031 and the outer wall of the shell 101. The top annular cavity of the third temperature control layer and the side annular cavity of the first temperature control layer are connected to form a whole. The thickness of the top annular cavity and the side annular cavity are both 600mm. The top insulation layer 1031 and the side insulation layer 1032 are both insulation cotton.

[0140] The second temperature control layer includes a thermal insulation support layer 1033 and a second ventilation channel layer 1035 for ventilation arranged in the thermal insulation support layer 1033. The second ventilation channel layer 1035 is a cylindrical channel that runs from one side of the thermal insulation support layer 1033 to the other side. The axis of the second ventilation channel layer 1035 is perpendicular to the axis of the shell 101. The second ventilation channel layer 1035 is located in the middle position in the height direction of the second thermal insulation layer 1022. The thermal insulation support layer 1033 is a heavy castable layer.

[0141] The internal effective diameter of the first shell 101 is 80m, the internal effective height is 12.5m, the maximum liquid level of the molten salt is 12m, the thickness of the third insulation layer 1021, the second insulation layer 1022 and the first insulation layer 1023 are all 1.5m, the thickness of the second temperature control layer is 2m, the thickness of the first temperature control layer is 100~300mm, the diameter of the second ventilation channel layer 1035 is DN100, and the distance between the top of the first molten salt pump tank 3 and the lowest liquid level surface of the first molten salt storage tank is more than 2 meters.

[0142] The structural dimensions of the second molten salt storage tank 2 are almost the same as those of the first molten salt storage tank 1, with the only difference being that the thickness of the third insulation layer 1021, the second insulation layer 1022 and the first insulation layer 1023 in the second molten salt storage tank 2 are all 2 m, the thickness of the insulation support layer 1033 is 2.5 m, and the thickness of the side insulation layer 1032 is 100-400 mm.

[0143] The first molten salt storage tank 1 is provided with a first inlet 105 and a first outlet 106, and the second molten salt storage tank 2 is provided with a second inlet 201 and a second outlet 202. The first inlet 105 is provided at the top of the first molten salt storage tank 1, the first outlet 106 is provided at the bottom side of the first molten salt storage tank 1, the second inlet 201 is provided at the top of the second molten salt storage tank 2, and the second outlet 202 is provided at the bottom side of the second molten salt storage tank 2. The first molten salt pump tank 3 and the heater 6 are sequentially provided between the first outlet 106 and the second inlet 201 along the flow direction of the low-temperature molten salt, and the second molten salt pump tank 4 and the heat exchanger 7 are sequentially provided between the second outlet 202 and the first inlet 105 along the flow direction of the high-temperature molten salt.

[0144] Molten salt pumps 5 are provided in both the first molten salt pump tank 3 and the second molten salt pump tank 4. The molten salt pump 5 in the first molten salt pump tank 3 is connected to the heater 6, and the molten salt pump 5 in the second molten salt pump tank 4 is connected to the heat exchanger 7. The molten salt pump 5 is a short-axis cantilever pump. The top of the first molten salt pump tank 3 is located below the lowest liquid level of the first molten salt storage tank 1 in the vertical direction, and the top of the second molten salt pump tank 4 is located below the lowest liquid level of the second molten salt storage tank 2 in the vertical direction.

[0145] Molten salt regulating valves 8 and flow meters 9 are provided between the first outlet 106 and the inlet of the first molten salt pump tank 3 , between the second outlet 202 and the inlet of the second molten salt pump tank 4 , between the outlet of the first molten salt pump tank 3 and the heater 6 , and between the outlet of the second molten salt pump tank 4 and the heat exchanger 7 .

[0146] The first molten salt storage tank 1, the second molten salt storage tank 2, the first molten salt pump tank 3, and the second molten salt pump tank 4 are all provided with a liquid level meter 10 and a thermometer 11 for monitoring the liquid level and temperature of the molten salt in the tanks.

[0147] A salt discharge pipe 12 is provided at the bottom of the first molten salt pump tank 3 and the bottom of the second molten salt pump tank 4 to discharge particulate matter generated by chemical reaction between the molten salt and the atmosphere and insulation material in the system. A stop valve 13 may also be provided on the salt discharge pipe 12 to control the switch of the salt discharge pipe 12.

[0148] A gas communication pipe 14 is connected between the first molten salt storage tank 1 and the second molten salt storage tank 2 , and the diameter of the gas communication pipe 14 is DN50.

[0149] The pipelines, molten salt regulating valve 8, heater 6, heat exchanger 7, first molten salt pump tank 3 and second molten salt pump tank 4 in the molten salt energy storage system are all provided with insulation structures on the outside, and the insulation structures are electric heating layers and insulation layers arranged outside the electric heating layers.

[0150] Example 2

[0151] The molten salt energy storage system described in Example 1 is operated, and the operation method includes:

[0152] During heat storage, the low-temperature molten salt in the first molten salt storage tank 1 enters the first molten salt pump tank 3 by gravity, and is then transported to the heater 6 by the molten salt pump 5 in the first molten salt pump tank 3 for heating, and then flows into the second molten salt storage tank 2;

[0153] When releasing heat, the high-temperature molten salt in the second molten salt storage tank 2 enters the second molten salt pump tank 4 by gravity, and is then transported to the heat exchanger 7 through the molten salt pump 5 in the second molten salt pump tank 4 for heat exchange, and then flows into the first molten salt storage tank 1.

[0154] The heat storage capacity of this embodiment is 10GWh, the heat storage medium adopts chloride salt (eutectic salt of NaCl, KCl, MgCl2), the melting point of molten salt is 390°C, the total amount of molten salt is 120,000 tons, the working temperature of the first molten salt storage tank 1 is 450°C, and the working temperature of the second molten salt storage tank 2 is 800°C.

[0155] During the operation of the molten salt energy storage system, the temperature in the insulation layer of the first molten salt storage tank 1 and the second molten salt storage tank 2 is also controlled, specifically including the following steps: using the side temperature measuring component 107 and the bottom temperature measuring component 108 to monitor the temperature of the molten salt in the first insulation layer 1023 and the second insulation layer 1022 in real time, and adjusting the thickness of the side insulation layer 1032 and the wind speed of the second ventilation channel layer 1035 according to the monitored temperature until the temperature monitored by the side temperature measuring component 107 and the bottom temperature measuring component 108 is 300~350℃.

[0156] In this embodiment, the thickness of the side insulation layer 1032 of the first molten salt storage tank 1 is 150 mm, the thickness of the side insulation layer 1032 of the second molten salt storage tank 2 is 180 mm, the wind speed of the first ventilation channel layer 1034 in the first molten salt storage tank 1 is 0~5 m / s, and the wind speed of the second ventilation channel layer 1035 is 0~15 m / s, the wind speed of the first ventilation channel layer 1034 in the second molten salt storage tank 2 is 0~8 m / s, and the wind speed of the second ventilation channel layer 1035 is 0~20 m / s.

[0157] When the temperature of the side temperature measuring component 107 and the bottom temperature measuring component 108 is 300-350° C., the temperature of the shell 101 is measured by the temperature measuring thermocouple arranged on the outer wall of the shell 101, which is about 80° C.

Claims

1. A molten salt storage tank, characterized in that: It comprises a shell, a heat insulating layer arranged inside the shell, and a temperature control layer arranged outside the shell; The heat insulation layer comprises a first heat insulation layer arranged at the inner side of the shell and a second heat insulation layer arranged at the inner bottom of the shell; The first heat insulation layer and the second heat insulation layer each include a plurality of heat insulation blocks, the plurality of heat insulation blocks are spliced ​​with each other, and there are assembly gaps between the heat insulation blocks; The first thermal insulation layer and the second thermal insulation layer are both provided with a temperature measuring component, and the temperature measuring component is used to monitor the temperature of the molten salt in the first thermal insulation layer and the second thermal insulation layer; The temperature control layer comprises a first temperature control layer arranged on the outer side of the shell and a second temperature control layer arranged on the bottom of the second heat insulation layer; The first temperature control layer comprises a first ventilation channel layer for heat exchange and a heat preservation layer, wherein the first ventilation channel layer is an annular cavity arranged around the side wall of the shell, and the heat preservation layer is arranged outside the first ventilation channel layer around the shell; The second temperature control layer includes a second ventilation channel layer for heat exchange; The first temperature control layer and the second temperature control layer are used to control the solidification of at least part of the molten salt in the assembly gap of the first insulation layer and the assembly gap of the second insulation layer, so as to seal the insulation layer and prevent the molten salt from flowing to the outside.

2. The molten salt storage tank according to claim 1, characterized in that: The second temperature control layer includes a heat insulation support layer and the second ventilation channel layer arranged in the heat insulation support layer.

3. The molten salt storage tank according to claim 1 or 2, characterized in that: The second ventilation channel layer is a cylindrical channel that runs from one side of the second temperature control layer to the other side, and the axis of the cylindrical channel is perpendicular to the axis of the shell; The second ventilation channel layer is arranged at a middle position in the height direction of the second temperature control layer.

4. The molten salt storage tank according to claim 1, characterized in that: The first thermal insulation layer and the second thermal insulation layer both include multiple thermal insulation layer units, each thermal insulation layer unit includes multiple thermal insulation blocks, the multiple thermal insulation blocks are spliced ​​with each other, and there are assembly gaps between the thermal insulation blocks.

5. The molten salt storage tank according to claim 4, characterized in that: At least two connection holes are arranged on the insulation block in the first insulation layer, and a plurality of connection columns are also arranged in the first insulation layer, and the connection holes of the upper and lower adjacent insulation blocks in each insulation layer unit in the first insulation layer are coaxially connected to the connection columns.

6. The molten salt storage tank according to claim 1, characterized in that: The heat insulation block is in the shape of a rectangle; one end of the heat insulation block is provided with a groove, and the other end is provided with a protrusion matched with the groove.

7. The molten salt storage tank according to claim 1, characterized in that: The shell is a shell without a bottom wall.

8. The molten salt storage tank according to claim 1, characterized in that: The temperature measuring component in the first heat insulation layer is located at 1 / 4 to 3 / 4 of the thickness of the inner wall of the first heat insulation layer; The temperature measuring component in the second heat insulation layer is located at 1 / 4 to 3 / 4 of the thickness from the inner wall of the second heat insulation layer.

9. The molten salt storage tank according to claim 1, characterized in that: The temperature control layer also includes a third temperature control layer arranged on the top of the outer wall of the shell, and the third temperature control layer is the same as the first temperature control layer.

10. The molten salt storage tank according to claim 1, characterized in that: The thermal insulation layer also includes a third thermal insulation layer arranged on the top of the inner wall of the shell, the third thermal insulation layer is connected to the top of the shell through a hanging member, the hanging member includes a support plate and a connecting rod, one end of the connecting rod is connected to the support plate, and the other end is connected to the top of the shell, the third thermal insulation layer is arranged on the support plate, and the third thermal insulation layer is provided with a hole along its thickness direction for the connecting rod to pass through.

11. A temperature control method for a molten salt storage tank, characterized in that: It is used to control the temperature of the molten salt in the thermal insulation layer of the molten salt storage tank according to any one of claims 1 to 10, and specifically includes: The temperature is monitored in real time using the temperature measuring components in the first insulation layer and the second insulation layer. According to the monitored temperature, the thickness of the insulation layer and / or the wind speed of the first ventilation channel layer are adjusted, and the wind speed of the second ventilation channel layer is adjusted until the temperature monitored by the temperature measuring component reaches a set threshold, and the set threshold is a temperature value below the melting point of the molten salt.

12. The temperature control method of a molten salt storage tank according to claim 11, characterized in that: The set threshold is a temperature value 40-120° C. lower than the melting point of the molten salt.

13. The temperature control method of a molten salt storage tank according to claim 11, characterized in that: The wind speed in the first ventilation channel layer is 0-20 m / s; The wind speed in the second ventilation channel layer is 0-20 m / s; The molten salt is chloride salt.

14. A molten salt energy storage system, characterized in that: It includes: A first molten salt storage tank and a second molten salt storage tank, wherein the first molten salt storage tank is used to carry low-temperature molten salt, and the second molten salt storage tank is used to carry high-temperature molten salt. Both the first molten salt storage tank and the second molten salt storage tank are the molten salt storage tanks described in any one of claims 1 to 10, and the outlet of the first molten salt storage tank is connected to the inlet of the second molten salt storage tank, and the inlet of the first molten salt storage tank is connected to the outlet of the second molten salt storage tank.

15. The molten salt energy storage system according to claim 14, characterized in that: The molten salt energy storage system further includes a first molten salt pump tank, a second molten salt pump tank, a heater and a heat exchanger, wherein the first molten salt pump tank and the second molten salt pump tank are both provided with molten salt pumps, and the first molten salt storage tank and the second molten salt storage tank are both provided with an inlet and an outlet, the first molten salt pump tank and the heater are sequentially arranged between the outlet of the first molten salt storage tank and the inlet of the second molten salt storage tank along the flow direction of the low-temperature molten salt, and the second molten salt pump tank and the heat exchanger are sequentially arranged between the outlet of the second molten salt storage tank and the inlet of the first molten salt storage tank along the flow direction of the high-temperature molten salt; The top of the first molten salt pump tank is located below the lowest liquid level of the first molten salt storage tank in the vertical direction, and the top of the second molten salt pump tank is located below the lowest liquid level of the second molten salt storage tank in the vertical direction.

16. The molten salt energy storage system according to claim 14 or 15, characterized in that: The molten salt energy storage system also includes a temperature control system, which is used to control the wind speed of the first ventilation channel layer and the wind speed of the second ventilation channel layer according to the temperature monitored by the temperature measuring component.

17. An operating method of a molten salt energy storage system according to any one of claims 14 to 16, characterized in that: It includes the following steps: During heat storage, the low-temperature molten salt in the first molten salt storage tank flows into the second molten salt storage tank after being heated; When releasing heat, the high-temperature molten salt in the second molten salt storage tank flows into the first molten salt storage tank after heat exchange.

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