Horizontal single-tank fused salt heat storage system and method

Abstract

The invention relates to a horizontal single-tank fused salt heat storage system and method, and relates to the technical field of fused salt heat storage, and the horizontal single-tank fused salt heat storage system comprises a fused salt single tank, a fused salt heater, a heat release heat exchanger, a fused salt pump and a fused salt sprayer. The molten salt single tank adopts a lower horizontal storage tank structure and a low-position arrangement design, so that the molten salt heater and the heat release heat exchanger are easier to realize high-position arrangement, meanwhile, the molten salt single tank has the function of a salt dredging tank, the system is simplified, and the occupied area and investment of the system are reduced. Through series connection design of the fused salt heater and the heat release heat exchanger, the fused salt heat storage system can operate a heat storage working condition, a heat release working condition and a working condition of storing and releasing at the same time, the requirement of a user for 24-hour stable steam supply is met, all devices are in a hot standby state all the time, operation control is easy, and the response speed is high.

Description

Technical Field

[0001] The invention relates to the technical field of molten salt heat storage, and in particular to a horizontal single-tank molten salt heat storage system. Background Art

[0002] The traditional molten salt double-tank heat storage system adopts the design of separating cold and hot molten salt. Through the circulation and heat exchange of cold and hot molten salt between the cold tank and the hot tank, the technical risk is reduced and the stability of the entire heat storage system is improved. The molten salt double-tank heat storage system can usually support a larger energy storage scale, which is of great significance for meeting large-scale and long-term energy storage needs. However, the molten salt double-tank heat storage system requires additional equipment and pipelines to achieve the separation and circulation of cold and hot molten salts, so the investment and operating costs are high, and the molten salt double-tank heat storage system involves more control logic and operation processes, which increases the complexity of the system and the difficulty of maintenance. In addition, since two independent tanks are required, the molten salt double-tank heat storage system usually occupies a large area, which may be a challenge for places with limited space.

[0003] With the advancement of energy storage technology, miniaturization and lightweighting have become important development directions for molten salt storage tanks. The molten salt single tank system can better meet the needs of miniaturized applications and provide convenient and efficient energy storage solutions for distributed energy systems, mobile energy systems, etc.

[0004] At present, there are several technical routes for single-tank molten salt heat storage technology. Among them, the upper part of the thermocline molten salt single tank stores high-temperature molten salt, and the lower part stores low-temperature molten salt. Since the hot and cold molten salts are stored in one tank at the same time, the tank body is subjected to large thermal stress during the storage-release process, especially the temperature gradient in the middle thermocline layer area is the largest, and the stress impact on the tank wall is also the greatest. In severe cases, it will cause molten salt leakage, affecting the safe operation of the molten salt single tank; the heat storage and heat release conditions of the single-pump molten salt single tank heat storage system can only be operated in time periods, and the user's 24-hour steam supply requirements cannot be met. In addition, the system contains equipment such as salt-dispersing tanks, which are complex to operate and occupy a large area. In combination with the steam supply needs of industry and commerce, designing a horizontal single-tank molten salt heat storage system to achieve 24-hour stable steam supply is an urgent problem to be solved. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a horizontal single-tank molten salt heat storage system and method, simplify the molten salt heat storage system, reduce the floor space, and achieve 24h stable steam supply.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides a horizontal single-tank molten salt heat storage system, including a molten salt single tank, a molten salt heater, a heat-releasing heat exchanger, a molten salt pump, and a molten salt sprayer; the outlet of the molten salt single tank is connected to the inlet of the molten salt heater through the molten salt pump; the outlet of the molten salt heater is connected to the inlet of the heat-releasing heat exchanger; the outlet of the heat-releasing heat exchanger is connected to the inlet of the molten salt single tank. The molten salt single tank is a horizontal storage tank, and a molten salt pump is inserted into the upper part thereof, and a molten salt sprayer is arranged; the molten salt flows into the molten salt single tank through the molten salt sprayer; the horizontal single-tank molten salt heat storage system adopts a high-low arrangement, with the molten salt single tank arranged at a low position, and the molten salt heater and the heat-releasing heat exchanger arranged at a high position.

[0007] Preferably, the positions of the molten salt heater and the heat-releasing heat exchanger can be interchanged according to actual conditions.

[0008] Preferably, the single molten salt tank is a horizontal storage tank.

[0009] Preferably, the heat storage medium in the single molten salt tank is a single molten salt or a multi-component mixed molten salt.

[0010] Preferably, the heat source of the molten salt heater is valley electricity, new energy electricity, solar energy, high-temperature steam or high-temperature flue gas.

[0011] Preferably, the horizontal single-tank molten salt heat storage system also includes an electric heating system, and electric heating devices are provided on the equipment, pipelines, and valves.

[0012] The technical solution of the present invention also provides a horizontal single-tank molten salt heat storage method, including the following working conditions:

[0013] a. Heat storage condition: the heat-releasing heat exchanger is in a non-operating state, the molten salt in the molten salt single tank is pumped out by the molten salt pump, flows into the molten salt heater, flows to the heat-releasing heat exchanger after the temperature rises, and then flows into the molten salt single tank; the molten salt is continuously circulated and heated, and the heat storage condition ends after it is heated to a specified temperature;

[0014] b. Heat release condition: the molten salt heater is in a non-operating state, the molten salt in the molten salt single tank is pumped out by the molten salt pump, flows to the molten salt heater, and then flows to the heat release heat exchanger, and flows into the molten salt single tank after the temperature is reduced; the molten salt is circulated and cooled, and the heat release condition ends after the temperature is reduced to the specified temperature;

[0015] c. Storage and release working condition: the molten salt in the molten salt single tank is pumped out by the molten salt pump, flows into the molten salt heater, flows to the heat release heat exchanger after the temperature rises, and flows into the molten salt single tank after the temperature drops; the molten salt is first heated and then cooled in one cycle. If the degree of heating is stronger than the degree of cooling, the molten salt is in a state of circulating heating; if the degree of heating is equal to the degree of cooling, the molten salt is in a state of constant temperature.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The molten salt single tank in the present invention adopts a horizontal storage tank structure with a smaller height and a low-position layout design, which makes it easier to arrange the molten salt heater and the heat release heat exchanger at a high position. At the same time, the molten salt single tank has the function of a salt-draining tank, which simplifies the system and reduces the system footprint and investment.

[0018] (2) The present invention adopts the design of connecting the molten salt heater and the heat release heat exchanger in series, so that the molten salt heat storage system can operate in heat storage mode, heat release mode and heat storage and release mode, thereby meeting the user's demand for 24-hour stable steam supply. In addition, each device is always in hot standby mode, with simple operation control and fast response speed.

[0019] (3) The present invention provides a molten salt sprayer on the molten salt tank so that the cold and hot molten salts can be quickly and evenly mixed during the heat storage and heat release process, thereby ensuring the safe operation of the molten salt tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a horizontal single-tank molten salt heat storage system.

[0021] Figure numerals: 1. Molten salt single tank; 2. Molten salt heater; 3. Heat release heat exchanger; 4. Molten salt pump; 5. Molten salt sprayer. DETAILED DESCRIPTION

[0022] The following will be combined with the 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, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present invention is a horizontal single-tank molten salt heat storage system. Figure 1 As shown, it includes a molten salt single tank 1, a molten salt heater 2, a heat release heat exchanger 3, a molten salt pump 4, and a molten salt sprayer 5; the outlet of the molten salt single tank 1 is connected to the inlet of the molten salt heater 2 through the molten salt pump 4; the outlet of the molten salt heater 2 is connected to the inlet of the heat release heat exchanger 3; the outlet of the heat release heat exchanger 3 is connected to the inlet of the molten salt single tank 1; the molten salt single tank 1 is a horizontal storage tank, the upper part of which is inserted with a molten salt pump 4 and a molten salt sprayer 5; the molten salt flows back to the molten salt single tank 1 through the molten salt sprayer 5; the horizontal single tank molten salt heat storage system adopts a high-low position arrangement, the molten salt single tank 1 is arranged at a low position, and the molten salt heater 2 and the heat release heat exchanger 3 are arranged at a high position. The horizontal single tank molten salt heat storage system also includes an electric heating system, and electric heating devices are arranged on equipment, pipelines, and valves.

[0024] As an optional embodiment, the positions of the molten salt heater 2 and the heat releasing heat exchanger 3 can be interchanged according to actual conditions; the heat storage medium in the molten salt tank 1 can be a single molten salt or a multi-component mixed molten salt; the heat source of the molten salt heater 2 can be valley electricity, new energy electricity, solar energy, high-temperature steam or high-temperature flue gas.

[0025] In this embodiment, Hitec ternary salt (53% KNO3 + 40% NaNO2 + 7% NaNO3) is used as molten salt, the operating temperature range is 240-370°C, the energy source is valley electricity, and 2.3Mpa, 220°C industrial steam is supplied externally. The horizontal single-tank molten salt heat storage system can flexibly switch between heat storage conditions, heat release conditions, and storage and release conditions according to different energy needs and grid load conditions to achieve efficient energy management and supply. The following are the specific operating procedures of these conditions:

[0026] Heat storage condition: In this mode, the heat-releasing heat exchanger 3 does not work. The molten salt is pumped out of the molten salt tank 1 by the molten salt pump 4, flows to the molten salt heater 2, the temperature rises in the heater, and then flows to the heat-releasing heat exchanger 3 (the heat-releasing heat exchanger 3 does not work at this time), and finally flows back to the molten salt tank 1. The molten salt is continuously heated in this process until it reaches the preset specified temperature (370℃), and the heat storage condition ends.

[0027] Heat release condition: In this mode, the molten salt heater 2 does not work. The molten salt is pumped out of the molten salt tank 1 by the molten salt pump 4, and the 370°C molten salt flows through the molten salt heater 2 (the molten salt heater 2 does not work at this time), and the temperature does not change. Then it flows to the heat release heat exchanger 3 to heat the feed water, generating 2.3Mpa, 220°C industrial steam for external supply. After the molten salt releases heat in the heat exchanger, the temperature drops and then flows back to the molten salt tank 1. The molten salt continues to cool down in this cycle until it reaches the preset specified temperature (240°C), and the heat release condition ends.

[0028] Storage and release condition: This is the operating mode of the system when the grid load is low. At this time, the molten salt heater 2 and the heat release heat exchanger 3 are both started. The molten salt in the molten salt single tank 1 is pumped out by the molten salt pump 4, and the 240°C molten salt flows through the molten salt heater 2 to be heated, and then flows into the heat release heat exchanger 3 to heat the feed water, generating 2.3Mpa, 220°C industrial steam for external use. In this embodiment, the molten salt temperature rises more than the temperature drop, and the molten salt is in a cycle heating. The temperature of the molten salt in the molten salt single tank 1 will gradually increase. When the molten salt temperature rises to 370°C, the storage and release condition ends.

[0029] The present invention provides a horizontal single-tank molten salt heat storage system, which is simple to operate, highly safe and highly stable. The molten salt single tank 1 adopts a horizontal storage tank structure with a smaller height and a low-position layout design, so that the molten salt heater 2 and the heat-releasing heat exchanger 3 are easier to realize high-position layout, and at the same time, the molten salt single tank 1 has the function of a salt-repelling tank, which simplifies the system and reduces the system footprint and investment. The present invention adopts a design in which the molten salt heater 2 and the heat-releasing heat exchanger 3 are connected in series, so that the molten salt heat storage system can operate in heat storage conditions, heat release conditions and storage and release conditions, thereby meeting the user's demand for 24-hour stable steam supply, and each device is always in a hot standby state, with simple operation control and fast response speed. The present invention arranges a molten salt sprayer 5 on the molten salt single tank 1, so that the cold and hot molten salts can be quickly and evenly mixed during the heat storage and heat release processes, thereby ensuring the safe operation of the molten salt single tank 1.

[0030] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A horizontal single-tank molten salt heat storage system, characterized in that: The invention comprises a molten salt single tank (1), a molten salt heater (2), a heat-releasing heat exchanger (3), a molten salt pump (4), and a molten salt sprayer (5); the outlet of the molten salt single tank (1) is connected to the inlet of the molten salt heater (2) through the molten salt pump (4); the outlet of the molten salt heater (2) is connected to the inlet of the heat-releasing heat exchanger (3); the outlet of the heat-releasing heat exchanger (3) is connected to the inlet of the molten salt single tank (1); the molten salt single tank (1) is a horizontal storage tank, the upper part of which is inserted with a molten salt pump (4) and provided with a molten salt sprayer (5); the molten salt flows back to the molten salt single tank through the molten salt sprayer (5); the horizontal single tank molten salt heat storage system adopts a high-low position arrangement, the molten salt single tank (1) is arranged at a low position, and the molten salt heater (2) and the heat-releasing heat exchanger (3) are arranged at a high position.

2. A horizontal single-tank molten salt heat storage system according to claim 1, characterized in that: The positions of the molten salt heater (2) and the heat-releasing heat exchanger (3) can be interchanged according to actual conditions.

3. A horizontal single-tank molten salt heat storage system according to claim 1, characterized in that: The molten salt single tank (1) is a horizontal storage tank.

4. A horizontal single-tank molten salt heat storage system according to claim 1, characterized in that: The heat storage medium in the molten salt single tank (1) is a single molten salt or a multi-component mixed molten salt.

5. A horizontal single-tank molten salt heat storage system according to claim 1, characterized in that: The heat source of the molten salt heater (2) is valley electricity, new energy electricity, solar energy, high-temperature steam or high-temperature flue gas.

6. A horizontal single-tank molten salt heat storage system according to claim 1, characterized in that: The horizontal single-tank molten salt heat storage system also includes an electric heating system, and electric heating devices are arranged on the equipment, pipelines and valves.

7. A horizontal single-tank molten salt heat storage system according to claim 1, characterized in that: A horizontal single-tank molten salt heat storage method is provided, including the following working conditions: a. Heat storage working condition: the heat-releasing heat exchanger (3) is in a non-operating state, the molten salt in the molten salt single tank (1) is pumped out by the molten salt pump (4), flows into the molten salt heater (2), and after the temperature rises, flows into the heat-releasing heat exchanger (3), and then flows into the molten salt single tank (1); The molten salt is heated in a cycle until it reaches a specified temperature, and the heat storage condition ends. b. Heat release condition: the molten salt heater (2) is in a non-operating state, the molten salt in the molten salt single tank (1) is pumped out by the molten salt pump (4), flows to the molten salt heater (2), and then flows to the heat release heat exchanger (3), and flows into the molten salt single tank (1) after the temperature is reduced; the molten salt is continuously circulated and cooled, and the heat release condition ends after the temperature is reduced to a specified temperature; c. Storage and release working condition: the molten salt in the molten salt single tank (1) is pumped out by the molten salt pump (4), flows into the molten salt heater (2), flows to the heat release heat exchanger (3) after the temperature rises, and flows into the molten salt single tank (1) after the temperature drops; the molten salt is first heated and then cooled in one cycle. If the degree of heating is greater than the degree of cooling, the molten salt is in a state of cyclic heating; if the degree of heating is equal to the degree of cooling, the molten salt is in a state of constant temperature.

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