Modularized skid-mounted heat storage and release integrated molten salt energy storage device

Abstract

The invention discloses a modular skid-mounted heat storage and release integrated fused salt energy storage device which comprises a fused salt box, and a fused salt steam generator is installed on the side wall of one end of the fused salt box in a tightly attached mode. A plurality of rows of vertically-arranged fused salt electric heating pipes are evenly installed in the fused salt box in the length direction of the fused salt box at intervals, a vertical baffle plate is arranged between every two adjacent rows of fused salt electric heating pipes, and a fused salt inlet pipe communicated with an outlet of the fused salt steam generator is installed on the lower portion of the end, close to the fused salt steam generator, of the fused salt box. A fused salt pump is installed at the end, away from the fused salt inlet pipe, in the fused salt box, and the discharging end of the fused salt pump communicates with an inlet of the fused salt steam generator through a fused salt outlet pipe. Modular design and skid-mounted installation are adopted, factory prefabrication and vehicle transportation are facilitated, under the condition that stable heat storage performance and heat release performance are guaranteed, the construction cost and the maintenance cost are greatly reduced, the construction difficulty is reduced, and the system is suitable for being used in small and medium-sized energy storage systems.

Description

Technical Field

[0001] This invention belongs to the field of molten salt energy storage technology, specifically relating to a modular skid-mounted integrated molten salt energy storage device for heat storage and release. Background Technology

[0002] Molten salt energy storage systems store excess electricity during off-peak hours by converting it into thermal energy in molten salt, and release the heat during peak hours to convert it back into electricity. This achieves peak shaving and valley filling, improves energy efficiency, and helps to save energy and reduce emissions.

[0003] Current molten salt energy storage systems typically employ a dual-tank design with separate cold and hot molten salts, relying on complex piping systems and pumping devices to achieve heat exchange between the cold and hot molten salts. This design is technically mature, reducing system operational risks while ensuring system stability during long-term heat storage, meeting the needs of large-scale energy storage. However, for small- to medium-scale energy storage systems, the dual-tank approach suffers from large footprint, complex system design, and high construction and maintenance costs. Therefore, we propose a molten salt energy storage device that achieves miniaturization, lightweight design, and skid-mountability while ensuring thermal storage stability. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a modular skid-mounted molten salt energy storage device that integrates heat storage and release, which is designed in a modular manner and installed on a skid. It can be prefabricated in the factory and has stable heat storage / release stability for small and medium-sized heat storage needs.

[0005] The technical solution adopted in this invention is: a modular skid-mounted integrated molten salt energy storage device, including a molten salt tank, a molten salt steam generator is installed in close contact with one side wall of the molten salt tank, a water inlet pipe is connected to the bottom inlet of the heat exchange coil of the molten salt steam generator, a steam outlet pipe is connected to the top outlet of the heat exchange coil of the molten salt steam generator, and the molten salt steam generator has an inlet at the top and an outlet at the bottom.

[0006] The molten salt tank is equipped with several rows of molten salt electric heating tubes evenly spaced along its length. Each row of molten salt electric heating tubes is installed vertically inside the molten salt tank. A vertical baffle is provided between two adjacent rows of molten salt electric heating tubes. Two adjacent vertical baffles are installed alternately at the bottom and top of the molten salt tank. A molten salt inlet pipe connected to the outlet of the molten salt steam generator is installed at the lower part of the molten salt tank near the molten salt steam generator. A molten salt pump is installed at the end of the molten salt tank away from the molten salt inlet pipe. The discharge end of the molten salt pump is connected to the inlet of the molten salt steam generator through a molten salt outlet pipe.

[0007] Preferably, the heat exchange tubes in the molten salt steam generator are arranged evenly from top to bottom, and the inlet and outlet of adjacent heat exchange tubes are connected by elbows. A transverse baffle is provided between adjacent heat exchange tubes, and two adjacent transverse baffles are installed alternately on opposite sides of the molten salt generator.

[0008] Preferably, the end of the molten salt outlet pipe away from the molten salt pump is connected to a distribution box, and multiple molten salt steam generators are arranged side by side. The multiple molten salt steam generators are installed on one side of the molten salt tank. The inlet of each molten salt steam generator is connected to the distribution box through a pipe, and the outlet of each molten salt steam generator is connected to the molten salt inlet pipe.

[0009] Preferably, the top end of the molten salt electric heating tube extends out of the molten salt tank and is fixedly connected to the top plate of the molten salt tank via a flange.

[0010] Preferably, a preheating sleeve is fixedly fitted outside the water inlet pipe. One end of the preheating sleeve, which is close to the molten salt steam generator, is connected to the steam outlet pipe through a pipeline, and the other end is provided with a steam outlet.

[0011] The beneficial effects of this invention are as follows:

[0012] (1) Through modular design and skid-mounted installation, while ensuring thermal storage stability, it can be prefabricated in the factory and assembled on site, which is convenient for transportation and deployment and reduces the construction cost of molten salt energy storage system;

[0013] (2) The molten salt tank is equipped with baffles, which can effectively increase the flow of molten salt, improve heat exchange efficiency, and increase the service life of the molten salt electric heater. At the same time, the molten salt tank is divided into multiple small and relatively independent spaces, which can form a sloping temperature layer with low temperature on one side and high temperature on the other side during the heat release process, avoiding the problem of low steam quality caused by the mixing of high and low temperature molten salt.

[0014] (3) The molten salt electric heater is installed vertically, which avoids the molten salt from depositing at the bottom due to gravity, which would cause the local temperature near the electric heating tube in the horizontal layout to be too high, resulting in the decomposition of the molten salt due to the high temperature.

[0015] (4) The molten salt electric heater is installed vertically and connected by a flange. If a molten salt electric heater fails or burns out, the faulty molten salt electric heater can be directly removed and replaced through the flange without stopping the machine to empty the molten salt in the molten salt tank.

[0016] (5) Transverse baffles are installed between the heat exchange tubes in the molten salt steam generator so that the molten salt flows from top to bottom in an S-shape and performs heat exchange step by step. This increases the flow of molten salt in the molten salt steam generator and increases the heat exchange efficiency. At the same time, the molten salt increases the flow velocity under the drive of gravity and gas pressure, which further improves the heat exchange efficiency. Moreover, the water flow direction is from bottom to top, which forms a counterflow with the molten salt flow direction, greatly improving the heat exchange efficiency.

[0017] (6) The molten salt steam generator is installed close to the side wall of the molten salt tank. After the equipment has been shut down for a long time, it is only necessary to turn on the molten salt electric heater to heat the molten salt in the molten salt tank. The heat in the molten salt tank can be conducted to the molten salt steam generator through the tank wall, so there is no need to add an additional electric heat tracing device, which reduces the equipment construction cost.

[0018] (7) Multiple molten salt steam generators can be set up in parallel according to actual needs. Compared with traditional molten salt energy storage systems, the steam production demand can be adjusted according to the actual project needs, and there is no need to equip a large number of electric heat tracing facilities, which greatly reduces construction costs and construction difficulties.

[0019] This invention adopts a modular design and skid-mounted installation, which facilitates factory prefabrication and vehicle transportation. While ensuring stable heat storage and heat release, it greatly reduces construction and maintenance costs and reduces construction difficulty, making it suitable for small and medium-sized energy storage systems. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the internal structure of the molten salt tank of the present invention;

[0022] Figure 3 This is a schematic diagram of the internal structure of the molten salt steam generator of the present invention.

[0023] In the diagram: 1. Molten salt tank; 2. Molten salt steam generator; 3. Water inlet pipe; 4. Steam outlet pipe; 5. Molten salt electric heating tube; 6. Vertical baffle; 7. Molten salt inlet pipe; 8. Molten salt pump; 9. Molten salt outlet pipe; 10. Horizontal baffle; 11. Diverter box; 12. Preheating sleeve; 13. Steam outlet. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] like Figure 1 , Figure 2 and Figure 3As shown, the modular skid-mounted integrated molten salt energy storage device provided in this embodiment includes a molten salt tank 1. A molten salt steam generator 2 is installed close to one side wall of the molten salt tank 1. In this embodiment, the shell of the molten salt steam generator 2 is made of carbon steel. The top of the molten salt steam generator 2 has an inlet, and the bottom has an outlet. Several rows of heat exchange tubes are evenly distributed from top to bottom inside the molten salt steam generator 2. In this embodiment, each row of heat exchange tubes has two tubes, and the heat exchange tubes are finned tubes. One end of the heat exchange tube in the uppermost layer is connected to a steam outlet pipe 4, and the other end is connected to the end of the adjacent heat exchange tube in the lower layer. The heat exchange tubes are connected by elbows. The inlet and outlet of two adjacent heat exchange tubes are connected by elbows. The elbows are located outside the shell of the molten salt steam generator 2. One end of the heat exchange tube at the bottom layer is connected to the water inlet pipe 3. Several transverse baffles 10 are also installed inside the molten salt steam generator 2. Each transverse baffle 10 is located between two adjacent heat exchange tubes, and two adjacent transverse baffles 10 are staggered on opposite sides of the molten salt generator. The transverse baffles 10 separate the heat exchange tubes on the adjacent sides, so that the molten salt flows in an S-shaped path from top to bottom, which increases the flow path of the molten salt and improves the heat exchange efficiency.

[0027] Several rows of molten salt electric heating tubes 5 are evenly installed along the length of the molten salt tank 1. Each row of molten salt electric heating tubes 5 is installed vertically in the molten salt tank 1. The bottom end of the molten salt electric heating tube 5 is located near the bottom surface of the molten salt tank 1, and the top end extends out of the molten salt tank 1 and is fixedly installed to the top plate of the molten salt tank 1 by a flange. A vertical baffle 6 is provided between two adjacent rows of molten salt electric heating tubes 5. Two adjacent vertical baffles 6 are staggered at the bottom and top of the molten salt tank 1, so that the molten salt flows in an S-shape in the molten salt tank 1.

[0028] The molten salt tank 1 is equipped with a molten salt inlet pipe 7 at the lower part of the end near the molten salt steam generator 2, which is connected to the outlet of the molten salt steam generator 2. A molten salt pump 8 is installed at the end of the molten salt tank 1 away from the molten salt inlet pipe 7. The molten salt pump 8 is fixedly installed on the outer top surface of the molten salt tank 1. The feed end of the molten salt pump 8 extends into the molten salt tank 1 and is located at the bottom surface of the molten salt tank 1. The discharge end of the molten salt pump 8 is connected to the inlet of the molten salt steam generator 2 through a molten salt outlet pipe 9.

[0029] The water inlet pipe 3 is fixedly fitted with a preheating sleeve 12. One end of the preheating sleeve 12, which is close to the molten salt steam generator 2, is connected to the steam outlet pipe 4 through a pipe, and the other end is provided with a steam outlet 13.

[0030] Example 2

[0031] This embodiment is basically the same as embodiment 1, except that according to the actual steam production requirements, a distribution box 11 and multiple parallel molten salt steam generators 2 are added. The end of the molten salt outlet pipe 9 away from the molten salt pump 8 is connected to the distribution box 11. Multiple molten salt steam generators 2 are arranged side by side. Multiple molten salt steam generators 2 are installed on one side of the molten salt box 1. The inlet of each molten salt steam generator 2 is connected to the distribution box 11 through a pipe, and the outlet of each molten salt steam generator 2 is connected to the molten salt inlet pipe 7.

[0032] The working principle of this invention: The molten salts used in this invention mainly employ binary molten salts and ternary molten salts;

[0033] Binary molten salt: It is usually made of two kinds of salts, the most common being a mixture of 60% sodium nitrate and 40% potassium nitrate, commonly known as "sun salt"; its melting point is about 207℃, and its working temperature can reach 600℃;

[0034] Ternary molten salt: It is a mixture of three salts, with a standard ratio of 53% potassium nitrate, 40% sodium nitrite and 7% sodium nitrate. Its melting point is 142℃ and its working temperature range is 142-450℃.

[0035] (1) Heat storage mode: turn on the molten salt electric heater and start the molten salt pump 8. In this mode, the molten salt steam generator 2 does not work and only serves as a molten salt flow channel for molten salt to flow. The low-temperature molten salt flows under the drive of the molten salt pump 8 and the molten salt electric heater heats the flowing low-temperature molten salt into high-temperature molten salt.

[0036] (2) Heat release mode: In this mode, the molten salt in the molten salt tank 1 is high-temperature molten salt. The molten salt pump 8 and the molten salt steam generator 2 are started. The high-temperature molten salt pump 8 is sent to the top inlet of the molten salt steam generator 2. The high-temperature molten salt enters the top of the molten salt steam generator 2 and flows in an S-shape from top to bottom under the separation of the transverse baffle 10. The water pump is started to pump the low-temperature deoxygenated water into the heat exchange tube through the water inlet pipe 3. The low-temperature deoxygenated water exchanges heat with the high-temperature superheated steam in the preheating sleeve 12 in the water inlet pipe 3 to raise its temperature. The deoxygenated water after being heated enters the heat exchange tube. The deoxygenated water flows in an S-shape from bottom to top in the heat exchange tubes of the molten salt steam generator 2, forming a countercurrent with the flow of molten salt. This heat exchange raises the temperature of the deoxygenated water, causing it to evaporate and superheat in the molten salt steam generator 2. High-temperature superheated steam is generated at the top of the molten salt steam generator 2. The high-temperature superheated steam enters the preheating jacket 12 through the steam outlet pipe 4 and preheats the low-temperature deoxygenated water in the outlet pipe. After cooling, medium-temperature steam is discharged at the steam outlet 13 of the preheating jacket 12 and supplied to the user. The low-temperature molten salt after heat exchange flows back into the molten salt tank 1.

[0037] (3) Simultaneous release and storage mode: In this mode, the molten salt steam generator 2 and the molten salt electric heater operate simultaneously, and the molten salt pump 8 is started. The entire system can be equivalently converted into a molten salt electric boiler to maximize the conversion of electrical energy into heat energy. In this working mode, the heat release and heat storage are consistent with the above-mentioned heat release and heat storage methods. The molten salt flows from the molten salt inlet pipe 7 of the molten salt tank 1 through the vertical baffle 6 to the feed end of the molten salt pump 8. It flows into the molten salt steam generator 2 from the top inlet of the molten salt steam generator 2 through the molten salt outlet pipe 9, flows down through the horizontal baffle 10 to the inlet of the molten salt inlet pipe 7, and then flows into the molten salt tank 1.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications and substitutions based on the technical solutions and concepts provided by the present invention should be covered within the scope of protection of the present invention.

Claims

1. A modular skid-mounted integrated molten salt energy storage device for heat storage and release, characterized in that: The molten salt tank (1) is attached to one side wall of the molten salt tank (1) and a molten salt steam generator (2) is installed close to it. The bottom inlet of the heat exchange coil of the molten salt steam generator (2) is connected to a water inlet pipe (3), and the top outlet of the heat exchange tube of the molten salt steam generator (2) is connected to a steam outlet pipe (4). The top of the molten salt steam generator (2) is provided with an inlet and the bottom is provided with an outlet. The molten salt tank (1) is equipped with several rows of molten salt electric heating tubes (5) evenly spaced along its length. Each row of molten salt electric heating tubes (5) is vertically installed in the molten salt tank (1). A vertical baffle (6) is provided between two adjacent rows of molten salt electric heating tubes (5). Two adjacent vertical baffles (6) are staggered at the bottom and top of the molten salt tank (1). A molten salt inlet pipe (7) connected to the outlet of the molten salt steam generator (2) is installed at the lower part of the molten salt tank (1) near the molten salt steam generator (2). A molten salt pump (8) is installed at the end of the molten salt tank (1) away from the molten salt inlet pipe (7). The discharge end of the molten salt pump (8) is connected to the inlet of the molten salt steam generator (2) through the molten salt outlet pipe (9).

2. The modular skid-mounted integrated molten salt energy storage device for heat storage and release according to claim 1, characterized in that: The heat exchange tubes in the molten salt steam generator (2) are evenly arranged from top to bottom. The inlet and outlet of adjacent heat exchange tubes are connected by elbows, and a transverse baffle (10) is provided between adjacent heat exchange tubes. Two adjacent transverse baffles (10) are staggered and installed on opposite sides of the molten salt generator.

3. A modular skid-mounted integrated molten salt energy storage device for heat storage and release according to claim 1 or 2, characterized in that: The end of the molten salt outlet pipe (9) away from the molten salt pump (8) is connected to a distribution box (11). Multiple molten salt steam generators (2) are arranged side by side. Multiple molten salt steam generators (2) are installed on one side of the molten salt tank (1). The inlet of each molten salt steam generator (2) is connected to the distribution box (11) through a pipe. The outlet of each molten salt steam generator (2) is connected to the molten salt inlet pipe (7).

4. The modular skid-mounted integrated molten salt energy storage device for heat storage and release according to claim 1, characterized in that: The top end of the molten salt electric heating tube (5) extends out of the molten salt tank (1) and is fixedly connected to the top plate of the molten salt tank (1) by a flange.

5. A modular skid-mounted integrated molten salt energy storage device for heat storage and release according to claim 1, characterized in that: The water inlet pipe (3) is fixedly fitted with a preheating sleeve (12). One end of the preheating sleeve (12) near the molten salt steam generator (2) is connected to the steam outlet pipe (4) through a pipe, and the other end is provided with a steam outlet (13).

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