Molten salt tank, molten salt energy storage device and energy storage method

Abstract

The invention discloses a fused salt tank, a fused salt energy storage device and an energy storage method in the field of fused salt energy storage devices.The fused salt tank comprises a tank body and a fused salt pump, the tank body is horizontally arranged, a groove is formed in the inner bottom of one side of the tank body in a downward protruding mode, and a fused salt inlet pipe used for being connected with equipment is arranged at the upper end of the other side of the tank body; the molten salt pump is provided with a suction inlet and an outlet pipe, and the suction inlet is formed in the groove. According to the molten salt tank provided by the invention, the groove is formed in the bottom in the tank body, and the molten salt pump suction inlet is formed in the groove, so that all molten salt in the tank body can be pumped out for use, and the utilization rate of the molten salt is improved. The molten salt pump used in the horizontal molten salt tank has the advantages of being short in pump shaft length, small in vibration, simple in structure, mature in technology and the like.

Description

Technical Field

[0001] The present invention relates to the field of molten salt energy storage devices, and in particular to a molten salt tank, a molten salt energy storage device and an energy storage method. Background Art

[0002] In recent years, with the vigorous promotion of renewable energy, the problem of wind and solar power abandonment has arisen due to the significant volatility and intermittency of new energy. A large number of photovoltaic power stations are passively "basking in the sun" and wind turbines are "sighing at the sight of the wind". The construction of new energy in some areas with serious "wind and solar power abandonment" has stagnated, seriously restricting the development of new energy in my country.

[0003] Molten salt energy storage is a highly efficient way of energy storage. It uses molten salt as a heat transfer and storage medium to store energy in the form of heat energy during the temperature rise of the molten salt. Molten salt energy storage generally adopts a dual-tank solution, with a low-temperature molten salt tank and a high-temperature molten salt tank. Molten salt acts as a heat transfer and storage medium, flowing between the high and low temperature storage tanks to achieve heat storage and release functions. It can provide a stable supply of heat energy during peak energy demand periods, especially showing great potential in solving the problem of wind and solar power abandonment. In recent years, molten salt energy storage has been increasingly used in solar thermal power stations, thermal power flexibility transformation, and industrial and commercial energy storage projects.

[0004] The existing molten salt tank is large in size and arranged vertically. A long molten salt pump needs to be installed inside. The long molten salt pump is costly and not very durable. In addition, a large pumping power is required when pumping the molten salt at the bottom. Therefore, some molten salt pumps are not completely installed at the bottom of the molten salt tank. As a result, the utilization rate of the molten salt is low. In addition, the vertically arranged molten salt tank requires a higher stable installation bracket, which increases the cost. Summary of the invention

[0005] The object of the present invention is to provide a molten salt tank, a molten salt energy storage device and an energy storage method to improve the utilization rate of molten salt and to reduce the power / shaft length of a molten salt pump.

[0006] In order to solve the above technical problems, the following technical solutions are adopted: In the first aspect, the present invention provides a molten salt tank, wherein the tank body is arranged horizontally, the inner bottom of one side of the tank body protrudes downward and is provided with a groove, and the other side end is provided with a molten salt inlet pipe for connecting to the equipment, and the molten salt pump is provided with a suction port and an outlet pipe, and the suction port is arranged in the groove.

[0007] Optionally, at least two supports are provided on the outer bottom of the tank body.

[0008] Optionally, a connecting pipe is provided on the tank body above the groove, an outer end of the connecting pipe is connected to one end of a bellows expansion joint, and a supporting platform for installing the molten salt pump is provided on the other end of the bellows expansion joint.

[0009] In a second aspect, the present invention provides a molten salt energy storage device, comprising the molten salt tank, a first pipeline, a second pipeline, a steam generator, a molten salt heater and a control system according to any one of the first aspects, wherein a plurality of the molten salt tanks are arranged in parallel, the molten salt tanks are filled with molten salt, the molten salt pump is controlled to start and stop by the control system, and the molten salt heater and the steam generator are controlled to start and stop by the control system; The outlet pipe on the molten salt tank is connected to the first pipeline, the molten salt inlet pipe is connected to the second pipeline, the molten salt inlet pipe of the steam generator and the molten salt inlet pipe of the molten salt heater are connected to the first pipeline, and the output end of the steam generator and the output end of the molten salt generator are connected to the second pipeline.

[0010] Optionally, at least one of the molten salt tanks is an empty molten salt tank not filled with molten salt.

[0011] Optionally, a check valve is provided on the outlet pipe, and a molten salt stop valve is provided on the molten salt inlet pipe, and the on-off of the molten salt stop valve is controlled by the control system.

[0012] Optionally, both the molten salt inlet pipe of the steam generator and the molten salt inlet pipe of the molten salt heater are provided with stop valves, and the on-off of the stop valves is controlled by the control system.

[0013] Optionally, the steam generator is provided with a water supply system and a steam delivery system.

[0014] In a third aspect, the present invention provides an energy storage method, which is implemented by the molten salt energy storage device according to any one of the second aspects, and comprises the following steps: The low-temperature molten salt in the molten salt tank is pumped by a molten salt pump and transported to the molten salt heater through a first pipeline for heating; The heated high-temperature molten salt is transported to the empty molten salt tank through the second pipeline until the molten salt in the molten salt tank is completely heated, and the empty molten salt tank is filled with high-temperature molten salt; the molten salt tank that originally outputs low-temperature molten salt becomes an empty molten salt tank, and the molten salt in the next low-temperature molten salt tank is heated and transported to the empty molten salt tank until the molten salt in the molten salt tank is completely high-temperature molten salt, completing energy storage.

[0015] In a fourth aspect, the present invention provides a heat release method, which is implemented by the molten salt energy storage device according to any one of the second aspects, comprising the following steps: The high-temperature molten salt in the molten salt tank is pumped by a molten salt pump and transported to the steam generator through a first pipeline for heat release; The molten salt after releasing heat is transported to the empty molten salt tank through the second pipeline. After all the heat in the molten salt tank is released, the empty molten salt tank is filled with low-temperature molten salt. The molten salt tank that originally outputs high-temperature molten salt becomes an empty molten salt tank, and the molten salt in the next high-temperature molten salt tank is transported to the empty molten salt tank to release heat until the molten salt in the molten salt tank is all low-temperature molten salt and the heat release is completed.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The molten salt tank provided by the present invention has a groove at the bottom of the tank body, and a molten salt pump suction port is arranged in the groove, so that all the molten salt in the tank body can be pumped out for use, thereby improving the utilization rate of the molten salt. The molten salt pump used in the horizontal molten salt tank has the advantages of short pump shaft length, small vibration, simple structure, and mature technology.

[0017] 2. The molten salt energy storage device provided by the present invention uses an external molten salt heater to heat the molten salt so that the molten salt is heated evenly. The molten salt tank is also connected to a steam generator. When the molten salt releases energy, it enters the steam generator for heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a molten salt tank in an embodiment of the present invention; Figure 2 It is a schematic diagram of the structure of a molten salt energy storage device in an embodiment of the present invention.

[0019] Description of reference numerals: 1. Molten salt tank; 2. Tank body; 3. Molten salt pump; 4. Inlet; 5. Outlet pipe; 6. Impeller; 7. Groove; 8. Support; 9. Connecting pipe; 901. Bellows expansion joint; 902. Support platform; 10. Molten salt inlet pipe; 11. Empty molten salt tank; 12. First pipeline; 13. Second pipeline; 14. Steam generator; 15. Molten salt heater; 16. Check valve; 17. Molten salt stop valve; 18. Steam stop valve; 19. Heating stop valve. DETAILED DESCRIPTION

[0020] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Example 1

[0021] like Figure 1As shown, this embodiment provides a molten salt tank 1, including a tank body 2 and a molten salt pump 3, the tank body 2 is arranged horizontally, the inner bottom of one side of the tank body 2 is protruding downward with a groove 7, and the other side end is provided with a molten salt inlet pipe 10 for connecting to the equipment, and the molten salt pump 3 is provided with a suction port 4 and an outlet pipe 5, the suction port 4 extending into the tank body 2 is arranged in the groove 7, and the suction port located in the groove 7 is provided with an impeller 6, and the impeller 6 is driven to rotate by the molten salt pump 3.

[0022] The tank body 2 is cylindrical, with a diameter not exceeding 5 meters and a length not exceeding 60 meters. It can be manufactured in a factory and transported to the project site for installation. Compared with a large tank body 2, its manufacturing is not affected by weather conditions, and product quality can be fully guaranteed.

[0023] An internal groove 7 is extended outward from the inner bottom of the tank body 2, and the groove 7 is used to place the suction port of the suction port 4 and the impeller 6. Through the rotation of the impeller 6, a negative pressure is generated in the center of the impeller 6, and the surrounding molten salt is sucked into the suction port and transported to the suction port 4. The groove 7 is the bottom position inside the tank body 2, and the molten salt in the tank body 2 can be sucked out for use.

[0024] The tank body 2 is arranged horizontally, and the pump shaft length of the molten salt pump is close to the diameter length. There is no need to use a long pump shaft. The molten salt pump 3 can completely suck out the molten salt in the tank body 2 for utilization with a relatively small power, which improves the durability of the molten salt pump 3 while also improving the utilization rate of the molten salt and reducing power costs.

[0025] The horizontally arranged tank body 2 is more stable, less susceptible to the influence of the external environment, and does not require complex structural support. Example 2

[0026] This embodiment provides a molten salt tank 1 based on Embodiment 1, except that: Two supports 8 are provided at the outer bottom of the tank body 2, and the tank body 2 is supported and installed by the supports 8. The two supports 8 are evenly arranged at the outer bottom of the tank body 2 near both ends.

[0027] A pipe 9 is provided just above the groove 7 of the tank body 2, one end of the pipe 9 is connected to the inside of the tank body 2, and the other end is connected to the bellows expansion joint 901. A support platform 902 is provided on the other end of the bellows expansion joint 901. The support platform 902 is used to set the molten salt pump 3, and the weight of the molten salt pump 3 is all borne by the support platform 902. The molten salt pump 3 is connected with a suction port 4 and an outlet pipe 5. The suction port 4 is located in the groove 7. An impeller 6 is also provided on the suction port 4. The impeller 6 is connected to the motor in the molten salt pump 3 through a transmission shaft, and the transmission shaft is located in the suction port 4.

[0028] In some embodiments, the impeller 6 may be located directly below the suction port 4. After entering the suction port 4 through the rotation of the impeller 6, the molten salt is pumped to the outlet pipe 5 for use by the molten salt pump 3. The impeller 6 may also be located directly above the suction port 4. In this case, the rotation direction of the impeller 6 is opposite to that of being located below the suction port 4. After the impeller 6 rotates, the principle is that the impeller 6 rotates, and a negative pressure is formed at the center of the impeller 6 to inhale the molten salt.

[0029] When in use, the molten salt tank 1 is filled with molten salt medium, and the molten salt pump 3 is turned on. After the molten salt pump 3 is turned on, the end impeller 6 also rotates, and the internal molten salt enters the suction port 4 from the suction port, and then enters the equipment through the outlet pipe 5 to act. The molten salt that has acted enters the molten salt tank 1 again through the molten salt inlet pipe 10. Example 3

[0030] This embodiment provides a molten salt energy storage device, including the molten salt tank 1 provided in embodiment 1 or embodiment 2, wherein a plurality of molten salt tanks 1 are arranged in parallel, and molten salt is filled in the molten salt tank 1. It also includes a first pipeline 12, a second pipeline 13, a steam generator 14, a molten salt heater 15, and a control system. The control system controls the start and stop of the molten salt pump 3 on the molten salt tank 1, thereby controlling the start and stop of the molten salt transportation.

[0031] like Figure 1 , Figure 2 As shown, the outlet pipe 5 on the molten salt pump 3 is connected to the first pipeline 12, the molten salt inlet pipe 10 is connected to the second pipeline 13, the molten salt inlet pipe of the steam generator 14 and the molten salt inlet pipe of the molten salt heater 15 are both connected to the first pipeline 12, and the output end of the steam generator 14 and the output end of the molten salt generator are both connected to the second pipeline 13.

[0032] When the molten salt releases energy, the molten salt in the molten salt tank 1 is transported to the steam generator 14 through the first pipeline 12 for heat exchange, and then the molten salt after the energy release is transported to the molten salt tank 1 through the second pipeline 13.

[0033] During molten salt energy storage, the molten salt is transported to the molten salt generator through the first pipeline 12 to heat the molten salt, and the heated molten salt is transported to the molten salt tank 1 through the second pipeline 13 for storage. Example 4

[0034] This embodiment provides a molten salt energy storage device based on the embodiment 3, except that: there is an empty molten salt tank 11 without molten salt among the plurality of molten salt tanks 1. In the process of releasing the molten salt energy, the molten salt after heat exchange in the steam generator 14 becomes low-temperature molten salt, and the low-temperature molten salt is discharged into the empty molten salt tank 11 through the second pipeline 13. After the empty molten salt tank 11 is filled, the original molten salt tank 1 becomes an empty molten salt tank 11.

[0035] like Figure 1As shown, a check valve 16 is also provided on the outlet pipe 5, and the outlet pipe 5 is connected to the first pipeline 12. The check valve 16 can prevent the molten salt in the outlet pipe 5 from flowing back into the tank body 2. A molten salt stop valve 17 is provided on the molten salt inlet pipe 10, and the molten salt inlet pipe 10 is connected to the second pipeline 13. The molten salt stop valve 17 is controlled by the control system. When the steam generator 14 or the molten salt heater 15 starts to work, the molten salt stop valve 17 corresponding to the empty molten salt tank 11 is opened, and the molten salt after the steam generator 14 or the molten salt heater 15 reacts is discharged into the empty molten salt tank 11.

[0036] A steam stop valve 18 is provided on the molten salt inlet pipe of the steam generator 14, and a heating stop valve 19 is provided on the molten salt inlet pipe of the molten salt heater 15. Both the steam stop valve 18 and the heating stop valve 19 are controlled on and off by a control system. The molten salt inlet pipe of the molten salt heater 15 and the molten salt inlet pipe of the steam generator 14 are connected to the first pipeline 12, and the output ends are connected to the second pipeline 13. The molten salt inlet pipe 10 on each tank body 2 is connected to the second pipeline 13.

[0037] The control system includes a controller and a molten salt tank 1 database, wherein the molten salt tank 1 database includes the molten salt tank 1 number corresponding to the low-temperature molten salt, the molten salt tank 1 number corresponding to the high-temperature molten salt, and the empty molten salt tank 1 number, and the controller receives the working signal of the steam generator 14 and the molten salt heater 15 to control the start and stop of the corresponding stop valve and the molten salt pump 3. Among them, the controller model can be selected from SPC-STW-S0402CTR.

[0038] Specifically, when the controller receives the start-up working signal of the steam generator 14, the molten salt pump 3 on the molten salt tank 1 corresponding to one of the high-temperature molten salts and the molten salt stop valve 17 corresponding to the empty molten salt tank 11 are opened in the molten salt tank 1 database, and the steam stop valve 18 is opened at the same time. The high-temperature molten salt is pumped to the steam generator 14 through the molten salt pump 3 for heat exchange, and the high-temperature molten salt becomes low-temperature molten salt, which is transported to the empty molten salt tank 11 through the second pipeline 13 until the molten salt in the high-temperature molten salt tank 1 is completely used up, and the molten salt pump 3 corresponding to the next high-temperature molten salt is turned on until the controller receives the steam generator 14 stop working signal and closes the corresponding molten salt pump 3 and the stop valve.

[0039] When the control system controls the steam to control the steam generator 14 to work according to demand, the steam stop valve 18 is controlled to open and the heating stop valve 19 is closed. At the same time, the molten salt pump 3 on one of the molten salt tanks 1 containing high-temperature molten salt is controlled to work, and the molten salt stop valve 17 corresponding to the empty molten salt tank 11 is opened. The high-temperature molten salt is transported to the steam generator 14 through the molten salt pump 3 for heat exchange, and the molten salt after heat exchange is transported to the empty molten salt tank 11.

[0040] The driving power supply of the molten salt heater 15 can be a grid power supply, a wind power supply, a photovoltaic power supply or other new energy sources. The molten salt heater 15 is driven by the driving power supply, so as to heat the molten salt and convert the energy into thermal energy storage in the molten salt. The steam generator 14 is externally connected to a water supply system and a steam system. After the heat exchange of the molten salt in the steam generator 14, the water is converted into water vapor and discharged through the steam system for use or used for energy conversion again.

[0041] In some embodiments, there are two empty molten salt tanks 11, two first pipes 12 and two second pipes 13, one end of a first pipe 12 is connected to the outlet pipe 5, and the other end is connected to the molten salt inlet pipe of the steam generator 14; one first pipe 12 is connected to the outlet pipe 5, and the other end is connected to the molten salt inlet pipe of the molten salt generator; one end of a second pipe 13 is connected to the output end of the steam generator 14, and the other end is connected to the molten salt inlet pipe 10; one end of a second pipe 13 is connected to the output end of the molten salt generator, and the other end is connected to the molten salt inlet pipe 10. The passage between the steam generator 14 and the molten salt heater 15 is separated, and the molten salt heater 15 and the steam generator 14 work simultaneously, and the two empty molten salt tanks 11 receive the molten salt from the steam generator 14 and the molten salt in the molten salt heater 15 respectively.

[0042] In some embodiments, the molten salt heater 15 and the steam generator 14 are arranged above a row of molten salt tanks 1. The molten salt after the reaction of the molten salt heater 15 and the steam generator 14 flows into the empty molten salt tank 11 by gravity, and flows into the designated empty molten salt tank 11 by the opening and closing of the molten salt stop valve 17. Example 5

[0043] This embodiment provides an energy storage method based on Embodiment 3 or Embodiment 4, comprising the following steps: The low-temperature molten salt in the molten salt tank is pumped by a molten salt pump and transported to the molten salt heater through a first pipeline for heating; The heated high-temperature molten salt is transported to the empty molten salt tank through the second pipeline until the molten salt in the molten salt tank is completely heated, and the empty molten salt tank is filled with high-temperature molten salt; the molten salt tank that originally outputs low-temperature molten salt becomes an empty molten salt tank, and the molten salt in the next low-temperature molten salt tank is heated and transported to the empty molten salt tank until the molten salt in the molten salt tank is completely high-temperature molten salt, completing energy storage. Example 6

[0044] The present invention provides a heat release method, comprising the following steps: The high-temperature molten salt in the molten salt tank is pumped by a molten salt pump and transported to the steam generator through a first pipeline for heat release; The molten salt after releasing heat is transported to the empty molten salt tank through the second pipeline. After all the heat in the molten salt tank is released, the empty molten salt tank is filled with low-temperature molten salt. The molten salt tank that originally outputs high-temperature molten salt becomes an empty molten salt tank, and the molten salt in the next high-temperature molten salt tank is transported to the empty molten salt tank to release heat until the molten salt in the molten salt tank is all low-temperature molten salt and the heat release is completed.

[0045] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, 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 it can be indirectly connected 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 the present invention can be understood by specific circumstances.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A molten salt tank, comprising a tank body and a molten salt pump, characterized in that: The tank body is arranged horizontally, the inner bottom of one side of the tank body protrudes downward and is provided with a groove, the other side end is provided with a molten salt inlet pipe for connecting to the equipment, the molten salt pump is provided with a suction port and an outlet pipe, and the suction port is arranged in the groove.

2. The molten salt tank according to claim 1, characterized in that: At least two supports are arranged on the outer bottom of the tank body.

3. The molten salt tank according to claim 1, characterized in that: A connecting pipe is provided on the tank body above the groove, the outer end of the connecting pipe is connected to one end of a bellows expansion joint, and the other end of the bellows expansion joint is connected to a flange of a molten salt pump, and the flange of the molten salt pump is supported on an independent supporting platform.

4. A molten salt energy storage device, characterized in that: The invention comprises the molten salt tank as claimed in any one of claims 1 to 3, and a first pipeline, a second pipeline, a steam generator, a molten salt heater and a control system, wherein a plurality of the molten salt tanks are arranged in parallel, the molten salt tanks are filled with molten salt, the molten salt pump is controlled to start and stop by the control system, and the molten salt heater and the steam generator are controlled to start and stop by the control system; The outlet pipe on the molten salt tank is connected to the first pipeline, the molten salt inlet pipe is connected to the second pipeline, the molten salt inlet pipe of the steam generator and the molten salt inlet pipe of the molten salt heater are connected to the first pipeline, and the output end of the steam generator and the output end of the molten salt generator are connected to the second pipeline.

5. The molten salt energy storage device according to claim 4, characterized in that: At least one of the molten salt tanks is an empty molten salt tank not filled with molten salt.

6. The molten salt energy storage device according to claim 4, characterized in that: The outlet pipe is provided with a check valve, the molten salt inlet pipe is provided with a molten salt stop valve, and the molten salt stop valve is controlled to be on and off by the control system.

7. The molten salt energy storage device according to claim 4, characterized in that: The molten salt inlet pipe of the steam generator and the molten salt inlet pipe of the molten salt heater are both provided with stop valves, and the on-off of the stop valves is controlled by the control system.

8. The molten salt energy storage device according to claim 4, characterized in that: The steam generator is provided with a water supply system and a steam delivery system.

9. An energy storage method, characterized in that: The method is implemented by the molten salt energy storage device according to any one of claims 5 to 8, comprising the following steps: The low-temperature molten salt in the molten salt tank is pumped by a molten salt pump and transported to the molten salt heater through a first pipeline for heating; The heated high-temperature molten salt is transported to the empty molten salt tank through the second pipeline until the molten salt in the molten salt tank is completely heated, and the empty molten salt tank is filled with high-temperature molten salt; the molten salt tank that originally outputs low-temperature molten salt becomes an empty molten salt tank, and the molten salt in the next low-temperature molten salt tank is heated and transported to the empty molten salt tank until the molten salt in the molten salt tank is completely high-temperature molten salt, completing energy storage.

10. A heat release method, characterized in that: The method is implemented by the molten salt energy storage device according to any one of claims 5 to 8, comprising the following steps: The high-temperature molten salt in the molten salt tank is pumped by a molten salt pump and transported to the steam generator through a first pipeline for heat release; The molten salt after releasing heat is transported to the empty molten salt tank through the second pipeline. After all the heat in the molten salt tank is released, the empty molten salt tank is filled with low-temperature molten salt. The molten salt tank that originally outputs high-temperature molten salt becomes an empty molten salt tank, and the molten salt in the next high-temperature molten salt tank is transported to the empty molten salt tank to release heat until the molten salt in the molten salt tank is all low-temperature molten salt and the heat release is completed.

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