Low-melting-point fused salt heat storage and heat transfer device

Abstract

The utility model discloses a low-melting-point fused salt heat storage and heat transfer device, which relates to the technical field of fused salt heat storage and heat transfer, and comprises a high-temperature fused salt tank and a low-temperature fused salt tank, one side of the high-temperature fused salt tank is connected with one side of the low-temperature fused salt tank through a double-strand winding tube type fused salt heat exchanger, and the double-strand winding tube type fused salt heat exchanger comprises a shell pass and a tube pass. The tube pass comprises a tube pass outlet, a plurality of tube pass inlets and a plurality of heat exchange tubes, the tube pass inlets are arranged below the shell pass, the tube pass outlet is arranged above the shell pass, the heat exchange tubes penetrate through the shell pass, the tube pass inlets are connected with the heat exchange tubes in a one-to-one correspondence mode, the heat exchange tubes are all connected with the tube pass outlet, and each heat exchange tube is arranged to be spiral. Different numbers of heat exchange tubes and tube pass inlets can be arranged, so that heat exchange of feed water at different temperatures is realized, the heat transfer coefficient is large, the heat transfer efficiency is higher, energy conservation and environmental protection can be achieved, and excellent economic benefits are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of molten salt heat storage and heat transfer, in particular to a low-melting-point molten salt heat storage and heat transfer device. Background Art

[0002] In the context of global carbon neutrality, clean energy will gradually replace fossil fuels. Wind power and photovoltaic power generation will become the absolute mainstay of clean energy, and installed capacity continues to increase. However, renewable energy generation suffers from instability, randomness, and intermittency, which places higher demands on grid frequency control. In this new power system, energy storage will become a crucial component, essential for renewable energy absorption and grid security, and the demand for this is extremely large.

[0003] In energy storage technology, molten salt (molten salt) heat storage belongs to the sensible heat storage in thermal energy storage technology. The molten salt is a commonly used medium and high temperature sensible heat storage medium with a wide liquid temperature range, a large heat storage temperature difference, and a high heat storage density. This technology is widely used in the field of large-scale solar thermal power generation. It can solve the problems of intermittent and instability of new energy and improve the efficiency of conventional power systems and regional energy systems.

[0004] The low-melting-point quaternary molten salt has a melting point of approximately 90°C and a decomposition temperature of approximately 630°C. Its operating temperature range reaches over 500°C, allowing for a high heat storage capacity. Molten salt thermal storage technology is not limited to solar thermal power generation but can also be applied to other industrial and civilian sectors, such as food processing, brewing, biopharmaceuticals, papermaking, chemicals, rubber, and other industries, providing hot water or steam, and has broad application prospects.

[0005] Based on this, a low-melting-point molten salt heat storage and heat transfer device is designed. Since the current difference in peak and valley electricity prices at night and during the day is getting bigger and bigger, the low-temperature molten salt is heated by utilizing the low electricity price period at night and the abandoned electricity. The flue gas discharged from the industry can also be utilized through a flue gas heater or an electric heater to heat the low-temperature molten salt and store the heat in the molten salt. Then, when needed, the heat in the high-temperature molten salt is released through a double-flow wound tube molten salt heat exchanger to generate hot water and steam for users. At the same time, the heat exchange tubes in the double-flow wound tube molten salt heat exchanger are set to a spiral shape, which has a higher heat exchange efficiency. Utility Model Content

[0006] The purpose of the utility model is to overcome the shortcomings of the existing technology and provide a low-melting-point molten salt heat storage and heat transfer device. The dual-stream wound tube molten salt heat exchanger is adopted. Compared with the traditional shell and tube heat exchanger, the heat transfer efficiency is higher and the dual-stream form is adopted. That is, in the heat exchanger, there are two tube passes and one shell pass. The two tube passes can carry water of different temperatures, and the shell pass carries high-temperature molten salt. After heat exchange, hot water and steam are generated at the same time for users to use. At the same time, the heat exchange tubes in the tube pass are arranged in a spiral shape, which has a higher heat exchange efficiency.

[0007] The purpose of the utility model is achieved through the following technical solutions: a low-melting-point molten salt heat storage and heat transfer device, the device includes a high-temperature molten salt tank for placing high-temperature molten salt and a low-temperature molten salt tank for placing low-temperature molten salt, one side of the high-temperature molten salt tank is connected to one side of the low-temperature molten salt tank through a double-stream wound tube molten salt heat exchanger, the double-stream wound tube molten salt heat exchanger includes a shell side and a tube side, the tube side includes a tube side outlet, several tube side inlets and several heat exchange tubes, the tube side inlet is arranged below the shell side, the tube side outlet is arranged above the shell side, the heat exchange tube runs through the shell side, and the tube side inlet and the heat exchange tube are connected one-to-one, that is, a The tube inlet is connected to a heat exchange tube, and different tube inlets will not be connected to the same heat exchange tube. Several heat exchange tubes are connected to the tube outlet. For example, if only one tube outlet is set, then several heat exchange tubes are connected to the same tube outlet. If two tube outlets are set, then each heat exchange tube is connected to two tube outlets. Each heat exchange tube is set in a spiral shape. In the molten salt heat transfer process, a double-flow wound tube molten salt heat exchanger is used to exchange heat between molten salt and water, release the heat in the molten salt, and generate hot water and water vapor for users. According to the needs of the user side, wound tube molten salt heat exchangers with different structures can be used.

[0008] The other side of the high-temperature molten salt tank is connected to the other side of the low-temperature molten salt tank through an electric heater. The high-temperature molten salt tank, the double-flow wound tube molten salt heat exchanger, the low-temperature molten salt tank and the electric heater form a closed loop.

[0009] The molten salt side pipeline for communication between the low-temperature molten salt tank and the electric heater is provided with a low-temperature molten salt pump, and the molten salt side pipeline for communication between the high-temperature molten salt tank and the double-flow wound tube molten salt heat exchanger is provided with a high-temperature molten salt pump.

[0010] The horizontal pipe of the molten salt side pipe used to connect the low-temperature molten salt tank and the electric heater forms an angle with the horizontal plane, and the angle is 3° to 5°. When the entire device stops working, the molten salt in the molten salt side pipe can flow into the low-temperature molten salt tank by gravity. Electric heating devices are provided at the four corners of the low-temperature molten salt tank to ensure that the molten salt will not solidify during the natural cooling process.

[0011] The dual-flow wound tube molten salt heat exchanger is connected to the deaerator. When hot water and water vapor are generated for users through the dual-flow wound tube molten salt heat exchanger, a bypass is set to introduce part or all of the water vapor into the deaerator, thereby heating the feed water in the deaerator and increasing the feed water temperature, which can improve the heat exchange efficiency of the dual-flow wound tube molten salt heat exchanger.

[0012] A molten salt inlet and a molten salt outlet are respectively provided at the upper and lower parts of one side of the shell side. The molten salt inlet is connected to a high-temperature molten salt tank, and the molten salt outlet is connected to a low-temperature molten salt tank.

[0013] The dual-stream wound tube molten salt heat exchanger includes a shell side and two tube sides, the tube side inlet includes a first tube side inlet and a second tube side inlet, the heat exchange tube includes a first heat exchange tube and a second heat exchange tube, the tube side outlet includes a first tube side outlet and a second tube side outlet, the first tube side inlet is connected to the first heat exchange tube, the second tube side inlet is connected to the second heat exchange tube, the first heat exchange tube and the second heat exchange tube are both connected to the tube side outlet, the tube side outlet is connected to one side of the deaerator, and the tube side inlet is connected to the other side of the deaerator.

[0014] A water feed pump is provided on the working medium side pipeline for communication between the tube side inlet and the deaerator.

[0015] The deaerator is also connected to a sodium ion exchanger.

[0016] The beneficial effects of the utility model are:

[0017] 1. The molten salt used in the present invention is a low-melting-point quaternary molten salt with a melting point of about 90°C and a decomposition temperature of about 630°C. The temperature operating range reaches more than 500 degrees Celsius. Compared with the commonly used binary and ternary molten salts, the use of this molten salt can store more heat, improve the efficiency of the entire device, and effectively improve the economy.

[0018] 2. The utility model utilizes the large difference between peak and valley electricity prices to heat low-temperature molten salt when electricity prices are low at night and when power is abandoned, or utilizes waste heat flue gas from industrial waste to heat the molten salt and store the heat in the molten salt. When needed, the double-flow wound tube molten salt heat exchanger is used to exchange heat between the feed water and the molten salt to generate hot water and water vapor for users.

[0019] 3. The utility model adopts a double-stream wound tube molten salt heat exchanger, which has higher heat transfer efficiency than the traditional shell and tube heat exchanger and adopts a double-stream form, that is, in this heat exchanger, there are two tube passes and one shell pass. The two tube passes can carry feed water of different temperatures, and the shell pass carries high-temperature molten salt. After heat exchange, hot water and steam are generated at the same time for users to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall layout structure of the utility model;

[0021] Figure 2 It is a structural diagram of a double-flow wound tube molten salt heat exchanger;

[0022] Figure 3 Schematic diagram of the inclination structure of the molten salt side pipeline used for communication between the low-temperature molten salt tank and the electric heater;

[0023] In the figure: 1- low-temperature molten salt tank, 2- high-temperature molten salt tank, 3- low-temperature molten salt pump, 4- high-temperature molten salt pump, 5- electric heater, 6- double-stream wound tube molten salt heat exchanger, 7- deaerator, 8- feed water pump, 9- molten salt side pipeline, 10- working fluid side pipeline, 11- sodium ion exchanger, 61- molten salt inlet, 62- molten salt outlet, 63- first tube side inlet, 64- second tube side inlet, 65- first tube side outlet, 66- second tube side outlet, 67- tube side, 68- shell side. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the utility model for protection, but merely represents selected embodiments of the present invention. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] In one embodiment of the present application:

[0027] like Figures 1 to 3As shown, a low-melting-point molten salt heat storage and heat transfer device includes a high-temperature molten salt tank 2 for placing high-temperature molten salt and a low-temperature molten salt tank 1 for placing low-temperature molten salt. One side of the high-temperature molten salt tank 2 is connected to one side of the low-temperature molten salt tank 1 through a double-stream wound tube molten salt heat exchanger 6. The double-stream wound tube molten salt heat exchanger 6 includes a shell side 68 and a tube side 67. The tube side 67 includes a tube side inlet, a tube side outlet and a heat exchange tube. The tube side inlet is arranged below the shell side 68, and the tube side outlet is arranged above the shell side 68. The heat exchange tube runs through the shell side 68, and the heat exchange tube is arranged in a spiral shape.

[0028] The other side of the high-temperature molten salt tank 2 is connected to the other side of the low-temperature molten salt tank 1 through the electric heater 5. The high-temperature molten salt tank 2, the double-flow wound tube molten salt heat exchanger 6, the low-temperature molten salt tank 1 and the electric heater 5 form a closed loop.

[0029] The molten salt side pipeline 9 for communication between the low-temperature molten salt tank 1 and the electric heater 5 is provided with a low-temperature molten salt pump 3, the electric heater 5 and the high-temperature molten salt tank 2 are connected through the molten salt side pipeline 9, the molten salt side pipeline 9 for communication between the high-temperature molten salt tank 2 and the double-flow wound tube molten salt heat exchanger 6 is provided with a high-temperature molten salt pump 4, and the double-flow wound tube molten salt heat exchanger 6 and the low-temperature molten salt tank 1 are connected through the molten salt side pipeline 9.

[0030] The transverse pipe of the molten salt side pipe 9 connecting the low-temperature molten salt tank 1 and the electric heater 5 forms a downward angle α with the horizontal plane, which is 3° to 5°. In this way, when the molten salt heat storage and heat transfer device stops working, the molten salt in the molten salt side pipe 9 can flow into the low-temperature molten salt tank 1 through the inclined pipe due to gravity.

[0031] The molten salt uses a low-melting-point quaternary molten salt. The low-temperature molten salt in the low-temperature molten salt tank 1 is pumped into the electric heater 5 (the electric heater 5 can be replaced by a flue gas heater) through the low-temperature molten salt pump 3. Taking advantage of the low electricity price at night and the curtailment of electricity and solar power, the electric heater 5 heats the low-temperature molten salt (the flue gas heater uses waste heat from industrial waste flue gas to heat the molten salt), stores the heat in the molten salt, completes the heat storage process of the molten salt, and turns it into high-temperature molten salt. The high-temperature molten salt then enters the high-temperature molten salt tank 2 through the molten salt side pipeline 9; when needed, the high-temperature molten salt in the high-temperature molten salt tank 2 can be pumped into the double-stream wound tube molten salt heat exchanger 6 through the high-temperature molten salt pump 4. After heat exchange with the feed water in the heat exchange tube in the shell side 68, the high-temperature molten salt releases heat and the temperature is reduced to low-temperature molten salt. The low-temperature molten salt enters the low-temperature molten salt tank 1, thereby completing the heat storage and heat transfer process of the molten salt. This process is a cycle, and the heated hot water and water vapor are supplied to users. The molten salt heat storage and heat transfer device is wrapped with electric heating on the outside of the molten salt side pipeline 9, the low-temperature molten salt tank 1, and the high-temperature molten salt tank 2. At the same time, the low-temperature molten salt tank 1 needs to be preheated before salt is injected into the low-temperature molten salt tank 1 to prevent the low-temperature molten salt tank 1 from generating excessive thermal stress. Specifically, four electric heating devices can be set at the four corners of the low-temperature molten salt tank 1. When the molten salt is naturally cooled to a certain temperature, the molten salt can be heated to prevent the molten salt in the low-temperature molten salt tank 1 from solidifying.

[0032] In another embodiment of the present application:

[0033] On the basis of the previous embodiment, this embodiment improves the double-stream wound tube molten salt heat exchanger 6 , and the double-stream wound tube molten salt heat exchanger 6 is connected to the deaerator 7 .

[0034] A molten salt inlet 61 and a molten salt outlet 62 are respectively provided at the upper and lower parts of one side of the shell side 68 . The molten salt inlet 61 is connected to the high-temperature molten salt tank 2 , and the molten salt outlet 62 is connected to the low-temperature molten salt tank 1 .

[0035] The dual-stream wound tube molten salt heat exchanger 6 includes a shell side 68 and two tube sides 67. The tube side inlet includes a first tube side inlet 63 and a second tube side inlet 64. The heat exchange tube includes a first heat exchange tube and a second heat exchange tube. The tube side outlet includes a first tube side outlet 65 and a second tube side outlet 66. The first tube side inlet 63 is connected to the first heat exchange tube, the second tube side inlet 64 is connected to the second heat exchange tube, the first heat exchange tube and the second heat exchange tube are both connected to the tube side outlet, the tube side outlet is connected to one side of the deaerator 7, and the tube side inlet is connected to the other side of the deaerator 7. The first tube side inlet 63 and the second tube side inlet 64 can respectively carry feed water of different temperatures, and heat exchange is carried out between high-temperature molten salt and feed water of different temperatures in the two tube sides 67 at the same time. The shell side 68 carries high-temperature molten salt, and after heat exchange, hot water and water vapor are generated at the same time. The hot water goes to the second tube side outlet 66, and the water vapor goes to the first tube side outlet 65 for user use. At the same time, according to user needs, different structures of the double-stream wound tube molten salt heat exchanger 6 can be replaced, such as single-stream, double-stream, triple-stream, etc. The single-stream is a shell side 68, a feed water inlet, a heat exchange tube, a hot water outlet, and a water vapor outlet. The feed water inlet is connected to the heat exchange tube, and the heat exchange tubes are all connected to the hot water outlet and the water vapor outlet. The triple-stream is a shell side 68, three feed water inlets, three heat exchange tubes, a hot water outlet, and a water vapor outlet, and so on. The feed water inlet is connected to the heat exchange tubes one by one, and each heat exchange tube is connected to the hot water outlet and the water vapor outlet.

[0036] A water feed pump 8 is provided on the working medium side pipeline 10 for communication between the pipe side inlet and the deaerator 7 .

[0037] The deaerator 7 is also connected to the sodium ion exchanger 11. The feed water first enters the sodium ion exchanger 11 to remove calcium and magnesium ions in the feed water, soften the feed water, and improve the feed water quality. Then, the feed water enters the deaerator 7 through the connected working medium side pipeline 10 for deoxygenation. After deoxygenation, the feed water is pumped into the double-flow wound tube molten salt heat exchanger 6 through the feed water pump 8. The feed water enters from the first tube side inlet 63 and the second tube side inlet 64, flows through the spiral heat exchange tube, and the high-temperature molten salt enters the shell side 68 from the molten salt inlet 61, exchanges heat with the feed water in the spiral heat exchange tube, and the high-temperature molten salt becomes low-temperature molten salt. The molten salt flows out from the molten salt outlet 62 and enters the low-temperature molten salt tank 1. The feed water becomes hot water and generates water vapor. The hot water flows out from the second pipe side outlet 66 and is supplied to the user through the working fluid side pipeline 10. The water vapor flows out from the first pipe side outlet 65 and is also supplied to the user through the working fluid side pipeline 10. At the same time, a part of the water vapor needs to be introduced into the deaerator 7 through the working fluid side pipeline 10. After mixing with the feed water in the deaerator 7, the feed water temperature is increased, thereby improving the heat exchange efficiency of the double-stream wound tube molten salt heat exchanger 6.

[0038] The above description is merely an embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant fields. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention shall be within the scope of protection of the appended claims.

Claims

1. A low-melting-point molten salt heat storage and heat transfer device, comprising a high-temperature molten salt tank (2) and a low-temperature molten salt tank (1), characterized in that: One side of the high-temperature molten salt tank (2) is connected to one side of the low-temperature molten salt tank (1) through a double-stream wound tube molten salt heat exchanger (6). The double-stream wound tube molten salt heat exchanger (6) includes a shell side (68) and a tube side (67). The tube side (67) includes a tube side outlet, several tube side inlets and several heat exchange tubes. The tube side inlet is arranged below the shell side (68), and the tube side outlet is arranged above the shell side (68). The heat exchange tube runs through the shell side (68), and the tube side inlet and the heat exchange tube are connected one by one. Several heat exchange tubes are connected to the tube side outlet, and each heat exchange tube is arranged in a spiral shape.

2. The low-melting-point molten salt heat storage and heat transfer device according to claim 1, characterized in that: The other side of the high-temperature molten salt tank (2) is connected to the other side of the low-temperature molten salt tank (1) via an electric heater (5); the high-temperature molten salt tank (2), the double-stream wound tube molten salt heat exchanger (6), the low-temperature molten salt tank (1) and the electric heater (5) form a closed loop.

3. The low-melting-point molten salt heat storage and heat transfer device according to claim 1, characterized in that: The other side of the high-temperature molten salt tank (2) is connected to the other side of the low-temperature molten salt tank (1) through a flue gas heater, and the high-temperature molten salt tank (2), the double-stream wound tube molten salt heat exchanger (6), the low-temperature molten salt tank (1) and the flue gas heater form a closed loop.

4. The low-melting-point molten salt heat storage and heat transfer device according to claim 2, characterized in that: A molten salt side pipeline (9) for communication between the low-temperature molten salt tank (1) and the electric heater (5) is provided with a low-temperature molten salt pump (3), and a molten salt side pipeline (9) for communication between the high-temperature molten salt tank (2) and the double-stream wound tube molten salt heat exchanger (6) is provided with a high-temperature molten salt pump (4).

5. The low-melting-point molten salt heat storage and heat transfer device according to claim 4, characterized in that: The horizontal pipe of the molten salt side pipe (9) for communication between the low-temperature molten salt tank (1) and the electric heater (5) forms an angle with the horizontal plane, and the angle is 3° to 5°. The four corners of the low-temperature molten salt tank (1) are all provided with electric heating devices.

6. The low-melting-point molten salt heat storage and heat transfer device according to claim 1, characterized in that: The dual-stream wound tube-type molten salt heat exchanger (6) is connected to the deaerator (7).

7. The low-melting-point molten salt heat storage and heat transfer device according to claim 6, characterized in that: A molten salt inlet (61) and a molten salt outlet (62) are respectively provided at the upper and lower parts of one side of the shell side (68); the molten salt inlet (61) is connected to the high-temperature molten salt tank (2), and the molten salt outlet (62) is connected to the low-temperature molten salt tank (1).

8. A low-melting-point molten salt heat storage and heat transfer device according to claim 6 or 7, characterized in that: The dual-stream wound tube molten salt heat exchanger (6) includes a shell side (68) and two tube sides (67), the tube side inlet includes a first tube side inlet (63) and a second tube side inlet (64), the heat exchange tube includes a first heat exchange tube and a second heat exchange tube, the tube side outlet includes a first tube side outlet (65) and a second tube side outlet (66), the first tube side inlet (63) is connected to the first heat exchange tube, the second tube side inlet (64) is connected to the second heat exchange tube, the first heat exchange tube and the second heat exchange tube are both connected to the tube side outlet, the tube side outlet is connected to one side of the deaerator (7), and the tube side inlet is connected to the other side of the deaerator (7).

9. The low-melting-point molten salt heat storage and heat transfer device according to claim 8, characterized in that: A water feed pump (8) is provided on the working medium side pipeline (10) for communication between the tube side inlet and the deaerator (7).

10. The low-melting-point molten salt heat storage and heat transfer device according to claim 8, characterized in that: The deaerator (7) is also connected to a sodium ion exchanger (11).

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