Fused salt energy storage system

Abstract

The utility model provides a fused salt energy storage system which comprises a boiler, a steam turbine unit, a generator and a fused salt energy storage unit. A cold salt outlet of a low-temperature fused salt storage tank, a cold end fused salt inlet of a first-stage fused salt preheater, a hot end fused salt outlet of the first-stage fused salt preheater, a cold end fused salt inlet of a second-stage fused salt preheater, a hot end fused salt outlet of the second-stage fused salt preheater and a cold end fused salt inlet of a steam fused salt heat exchanger are arranged in the steam fused salt heat exchanger. A hot-end fused salt outlet of the steam fused salt heat exchanger is sequentially communicated with a hot salt inlet of the high-temperature fused salt storage tank through a pipeline, a steam extraction opening of the medium-pressure cylinder is communicated with a hot-end steam inlet of the first-stage fused salt preheater through a pipeline, and a steam exhaust opening of the high-pressure cylinder is communicated with a reheater inlet of the boiler through a pipeline and communicated with a hot-end steam inlet of the second-stage fused salt preheater. A reheater outlet of the boiler communicates with a steam inlet of the intermediate-pressure cylinder through a pipeline and communicates with a hot end steam inlet of the steam molten salt heat exchanger. The multi-stage heat source can be fully utilized, and gradient utilization of steam heat is achieved.

Description

Technical Field

[0001] This utility model relates to an energy storage system, specifically a molten salt energy storage system, belonging to the field of combined heat and power technology. Background Technology

[0002] With the optimization of the energy structure and the rapid development of renewable energy, thermal power plants face the dual challenges of improving flexibility and efficiency. Traditional thermal power plants often encounter efficiency declines during peak shaving, and the grid connection of large-scale fluctuating renewable energy sources further exacerbates this contradiction. To address these issues, molten salt energy storage technology has attracted widespread attention due to its large capacity and low cost.

[0003] A common problem with existing molten salt energy storage systems in thermal power plants is the failure to effectively utilize the cascaded heat of steam. Most systems focus only on utilizing a single heat source, i.e., the steam heat source at a specific stage, such as using only the exhaust steam from the high-pressure cylinder, while neglecting the thermal energy potential contained in the exhaust steam from turbines at different pressure levels. Utilizing a single heat source leads to the waste of thermal energy of varying grades, reducing the overall energy efficiency of the system. Utility Model Content

[0004] Based on the above background, the purpose of this utility model is to provide a molten salt energy storage system that can make full use of multiple heat sources and realize the cascade utilization of steam heat.

[0005] To achieve the above-mentioned objectives, this utility model provides the following technical solution:

[0006] A molten salt energy storage system includes a boiler, a steam turbine unit, a generator, and a molten salt energy storage unit. The steam turbine unit includes a low-pressure cylinder, an intermediate-pressure cylinder, a high-pressure cylinder, and a reflux unit. The boiler supplies main steam to the high-pressure cylinder and reheat steam to the intermediate-pressure cylinder via pipelines. The low-pressure, intermediate-pressure, and high-pressure cylinders drive the generator to generate electricity. The molten salt energy storage unit includes a cryogenic molten salt storage tank, a primary molten salt preheater, a secondary molten salt preheater, a steam-molten salt heat exchanger, and a high-temperature molten salt storage tank. The cryogenic molten salt storage tank has a cold salt outlet, the primary molten salt preheater has a cold-end molten salt inlet, the primary molten salt preheater has a hot-end molten salt outlet, and the secondary molten salt storage unit... The cold-end molten salt inlet of the molten salt preheater, the hot-end molten salt outlet of the secondary molten salt preheater, the cold-end molten salt inlet of the steam-molten salt heat exchanger, the hot-end molten salt outlet of the steam-molten salt heat exchanger, and the hot salt inlet of the high-temperature molten salt storage tank are connected in sequence through pipelines. The steam extraction port of the intermediate-pressure cylinder is connected to the hot-end steam inlet of the primary molten salt preheater through a pipeline. The steam exhaust port of the high-pressure cylinder is connected to the reheater inlet of the boiler through a pipeline, and is also connected to the hot-end steam inlet of the secondary molten salt preheater through a pipeline. The reheater outlet of the boiler is connected to the steam inlet of the intermediate-pressure cylinder through a pipeline, and is also connected to the hot-end steam inlet of the steam-molten salt heat exchanger through a pipeline.

[0007] Preferably, the molten salt energy storage unit also includes a molten salt steam heat exchanger and a steam pressure matching device. The hot salt outlet of the high-temperature molten salt tank, the hot-end molten salt inlet of the molten salt steam heat exchanger, the cold-end molten salt outlet of the molten salt steam heat exchanger and the cold salt inlet of the low-temperature molten salt tank are connected in sequence through pipelines. The cold-end steam outlet of the primary molten salt preheater, the cold-end steam outlet of the secondary molten salt preheater and the cold-end steam outlet of the steam molten salt heat exchanger are all connected to the inlet of the steam pressure matching device through pipelines.

[0008] Preferably, the cold end water inlet of the molten salt steam heat exchanger is used to connect to an external water supply, and the hot end steam outlet of the molten salt steam heat exchanger is used to supply steam to the turbine unit.

[0009] Preferably, a steam pressure matching device is used to regulate the steam pressure and temperature before supplying steam to the outside.

[0010] Preferably, the molten salt energy storage unit also includes a high-temperature molten salt pump and a low-temperature molten salt pump. The high-temperature molten salt pump is located between the hot salt outlet of the high-temperature molten salt tank and the hot-end molten salt inlet of the molten salt steam heat exchanger, and the low-temperature molten salt pump is located between the cold salt outlet of the low-temperature molten salt tank and the cold-end molten salt inlet of the first-stage molten salt preheater.

[0011] Preferably, the molten salt energy storage unit also includes an electric heater, which is located between the hot end molten salt outlet of the steam molten salt heat exchanger and the hot salt inlet of the high-temperature molten salt storage tank.

[0012] Preferably, the reflux unit includes a condenser, a low-pressure heater, a deaerator, and a high-pressure heater. The exhaust port of the low-pressure cylinder, the condenser, the low-pressure heater, the deaerator, the high-pressure heater, and the economizer inlet of the boiler are connected in sequence through pipelines.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] This utility model discloses a molten salt energy storage system that combines molten salt energy storage with innovative multi-stage heat recovery to achieve efficient energy storage and peak shaving and cascade utilization of thermal energy in power plants. The system can store excess thermal energy in high-temperature molten salt during periods of low electricity demand and release the thermal energy through the molten salt to generate electricity during peak demand periods, effectively smoothing grid load fluctuations. The system uses low-temperature extracted steam from the intermediate-pressure cylinder to preheat the low-temperature molten salt in a first-stage molten salt preheater, and uses high-temperature steam discharged from the high-pressure cylinder to further increase the molten salt temperature in a second-stage molten salt preheater. Finally, high-temperature steam from the boiler reheater outlet heats the molten salt to an even higher temperature in a steam-molten salt heat exchanger. This step-by-step heating design not only significantly improves heat exchange efficiency but also realizes cascade utilization of steam heat to maximize the recovery of thermal energy of different grades. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a molten salt energy storage system according to the present invention;

[0017] In the diagram: 1. Boiler; 2. Low-pressure cylinder; 3. Medium-pressure cylinder; 4. High-pressure cylinder; 5. Generator; 6. Low-temperature molten salt storage tank; 7. Primary molten salt preheater; 8. Secondary molten salt preheater; 9. Steam-molten salt heat exchanger; 10. High-temperature molten salt storage tank; 11. Molten salt steam heat exchanger; 12. Steam pressure matching device; 13. High-temperature molten salt pump; 14. Low-temperature molten salt pump; 15. Electric heater; 16. Condenser; 17. Low-pressure heater; 18. Deaerator; 19. High-pressure heater. Detailed Implementation

[0018] The technical solution of this utility model will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of this utility model is not limited to the following embodiments, and any modifications and / or alterations made to this utility model will fall within the protection scope of this utility model.

[0019] In this invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the field. Unless otherwise specified, the methods in the following embodiments are conventional methods in the field. Unless otherwise specified, the components or equipment in the following embodiments are general standard parts or components known to those skilled in the art, and their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0020] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following detailed description, many specific details are set forth to facilitate explanation and provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may be practiced by those skilled in the art without these specific details.

[0021] like Figure 1 As shown, an embodiment of this utility model discloses a molten salt energy storage system, including a boiler 1, a steam turbine unit, a generator 5, and a molten salt energy storage unit.

[0022] Boiler 1 is a conventional boiler for thermal power generation, which typically includes an economizer, superheater, reheater, and steam drum.

[0023] The turbine unit includes a low-pressure cylinder 2, an intermediate-pressure cylinder 3, a high-pressure cylinder 4, and a recirculation unit. The boiler 1 supplies main steam to the high-pressure cylinder 4 and reheat steam to the intermediate-pressure cylinder 3 through pipelines. The low-pressure cylinder 2, intermediate-pressure cylinder 3, and high-pressure cylinder 4 are used to drive the generator 5 to generate electricity.

[0024] The molten salt energy storage unit includes a low-temperature molten salt storage tank 6, a primary molten salt preheater 7, a secondary molten salt preheater 8, a steam-molten salt heat exchanger 9, and a high-temperature molten salt storage tank 10.

[0025] The cold salt outlet of the low-temperature molten salt storage tank 6, the cold end molten salt inlet of the primary molten salt preheater 7, the hot end molten salt outlet of the primary molten salt preheater 7, the cold end molten salt inlet of the secondary molten salt preheater 8, the hot end molten salt outlet of the secondary molten salt preheater 8, the cold end molten salt inlet of the steam molten salt heat exchanger 9, the hot end molten salt outlet of the steam molten salt heat exchanger 9, and the hot salt inlet of the high-temperature molten salt storage tank 10 are connected in sequence through pipelines.

[0026] The extraction port of the intermediate-pressure cylinder 3 is connected to the hot-end steam inlet of the primary molten salt preheater 7 via a pipeline. The exhaust port of the high-pressure cylinder 4 is connected to the reheater inlet of the boiler 1 via a pipeline, and also to the hot-end steam inlet of the secondary molten salt preheater 8 via a pipeline. The reheater outlet of the boiler 1 is connected to the steam inlet of the intermediate-pressure cylinder 3 via a pipeline, and also to the hot-end steam inlet of the steam-molten salt heat exchanger 9 via a pipeline.

[0027] The molten salt energy storage unit also includes a molten salt steam heat exchanger 11 and a steam pressure matching device 12. The hot salt outlet of the high-temperature molten salt storage tank 10, the hot-end molten salt inlet of the molten salt steam heat exchanger 11, the cold-end molten salt outlet of the molten salt steam heat exchanger 11, and the cold salt inlet of the low-temperature molten salt storage tank 6 are connected in sequence through pipelines. The cold-end steam outlet of the primary molten salt preheater 7, the cold-end steam outlet of the secondary molten salt preheater 8, and the cold-end steam outlet of the steam molten salt heat exchanger 9 are all connected to the inlet of the steam pressure matching device 12 through pipelines.

[0028] The cold end water inlet of the molten salt steam heat exchanger 11 is used to connect to the external water supply, and the hot end steam outlet of the molten salt steam heat exchanger 11 is used to supply steam to the turbine unit.

[0029] Among them, the steam pressure matching device 12 is used to supply steam to the outside after regulating the steam pressure and temperature.

[0030] The molten salt energy storage unit also includes a high-temperature molten salt pump 13 and a low-temperature molten salt pump 14. The high-temperature molten salt pump 13 is located between the hot salt outlet of the high-temperature molten salt storage tank 10 and the hot-end molten salt inlet of the molten salt steam heat exchanger 11. The low-temperature molten salt pump 14 is located between the cold salt outlet of the low-temperature molten salt storage tank 6 and the cold-end molten salt inlet of the first-stage molten salt preheater 7.

[0031] The molten salt energy storage unit also includes an electric heater 15, which is located between the hot end molten salt outlet of the steam molten salt heat exchanger 9 and the hot salt inlet of the high-temperature molten salt storage tank 10.

[0032] The reflux unit includes a condenser 16, a low-pressure heater 17, a deaerator 18, and a high-pressure heater 19. The exhaust port of the low-pressure cylinder 2, the condenser 16, the low-pressure heater 17, the deaerator 18, the high-pressure heater 19, and the economizer inlet of the boiler 1 are connected in sequence through pipelines.

[0033] The pipelines mentioned above should be equipped with corresponding regulating valves according to flow regulation requirements.

[0034] During normal operation, the high-temperature, high-pressure main steam generated by boiler 1 first enters high-pressure cylinder 4 to perform work. Part of the medium-temperature, medium-pressure steam discharged from high-pressure cylinder 4 enters the reheater of boiler 1 for reheating, while the other part is introduced into the secondary molten salt preheater 8 to heat the molten salt. The reheated high-temperature steam is divided into two paths: one enters the intermediate-pressure cylinder 3 to continue performing work, and the other enters the steam-molten salt heat exchanger 9 to heat the molten salt to its maximum temperature. During the work process, intermediate-pressure cylinder 3 extracts a certain amount of steam from its extraction port and introduces it into the primary molten salt preheater 7 for preliminary heating of the molten salt.

[0035] The heating process of molten salt follows the principle of stepped heating. First, the cold molten salt from the low-temperature molten salt storage tank 6 enters the primary molten salt preheater 7, where it exchanges heat with the steam extracted from the intermediate-pressure cylinder 3, resulting in an initial temperature increase. Then, the preheated molten salt enters the secondary molten salt preheater 8, where it exchanges heat with the higher-temperature steam from the high-pressure cylinder 4, further increasing its temperature. Finally, the molten salt enters the steam-molten salt heat exchanger 9, where it exchanges heat with the high-temperature steam from the reheater outlet of boiler 1, reaching its maximum temperature, and is then stored in the high-temperature molten salt storage tank 10.

[0036] During periods of low grid load, the system stores excess heat energy as high-temperature molten salt using the methods described above. When grid demand increases, the stored high-temperature molten salt can release heat energy to generate steam to drive turbine generators, thereby achieving peak shaving.

[0037] This system achieves efficient energy storage and peak shaving, as well as cascaded utilization of thermal energy in power plants, through molten salt energy storage combined with innovative multi-stage heat recovery.

[0038] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A molten salt energy storage system, characterized in that: The molten salt energy storage system includes a boiler (1), a steam turbine unit, a generator (5), and a molten salt energy storage unit. The steam turbine unit includes a low-pressure cylinder (2), a medium-pressure cylinder (3), a high-pressure cylinder (4), and a reflux unit. The boiler (1) supplies main steam to the high-pressure cylinder (4) and reheat steam to the medium-pressure cylinder (3) through pipelines. The low-pressure cylinder (2), the medium-pressure cylinder (3), and the high-pressure cylinder (4) are used to drive the generator (5) to generate electricity. The molten salt energy storage unit includes a low-temperature molten salt tank (6), a primary molten salt preheater (7), a secondary molten salt preheater (8), a steam-molten salt heat exchanger (9), and a high-temperature molten salt tank (10). The low-temperature molten salt tank (6) has a cold salt outlet, the primary molten salt preheater (7) has a cold end molten salt inlet, and the primary molten salt preheater (7) has a cold end molten salt inlet. The hot end molten salt outlet, the cold end molten salt inlet of the secondary molten salt preheater (8), the hot end molten salt outlet of the secondary molten salt preheater (8), the cold end molten salt inlet of the steam molten salt heat exchanger (9), the hot end molten salt outlet of the steam molten salt heat exchanger (9) and the hot salt inlet of the high temperature molten salt storage tank (10) are connected in sequence through pipelines. The steam extraction port of the intermediate pressure cylinder (3) is connected to the hot end steam inlet of the primary molten salt preheater (7) through a pipeline. The steam exhaust port of the high pressure cylinder (4) is connected to the reheater inlet of the boiler (1) through a pipeline, and is also connected to the hot end steam inlet of the secondary molten salt preheater (8) through a pipeline. The reheater outlet of the boiler (1) is connected to the steam inlet of the intermediate pressure cylinder (3) through a pipeline, and is also connected to the hot end steam inlet of the steam molten salt heat exchanger (9) through a pipeline.

2. The molten salt energy storage system according to claim 1, characterized in that: The molten salt energy storage unit also includes a molten salt steam heat exchanger (11) and a steam pressure matching device (12). The hot salt outlet of the high-temperature molten salt tank (10), the hot end molten salt inlet of the molten salt steam heat exchanger (11), the cold end molten salt outlet of the molten salt steam heat exchanger (11) and the cold salt inlet of the low-temperature molten salt tank (6) are connected in sequence through pipelines. The cold end steam outlet of the first-stage molten salt preheater (7), the cold end steam outlet of the second-stage molten salt preheater (8) and the cold end steam outlet of the steam molten salt heat exchanger (9) are all connected to the inlet of the steam pressure matching device (12) through pipelines.

3. The molten salt energy storage system according to claim 2, characterized in that: The cold end water inlet of the molten salt steam heat exchanger (11) is used to connect to the external water supply, and the hot end steam outlet of the molten salt steam heat exchanger (11) is used to supply steam to the turbine unit.

4. A molten salt energy storage system according to claim 2, characterized in that: The steam pressure matching device (12) is used to supply steam to the outside after adjusting the steam pressure and temperature.

5. A molten salt energy storage system according to claim 2, characterized in that: The molten salt energy storage unit also includes a high-temperature molten salt pump (13) and a low-temperature molten salt pump (14). The high-temperature molten salt pump (13) is located between the hot salt outlet of the high-temperature molten salt tank (10) and the hot-end molten salt inlet of the molten salt steam heat exchanger (11). The low-temperature molten salt pump (14) is located between the cold salt outlet of the low-temperature molten salt tank (6) and the cold-end molten salt inlet of the first-stage molten salt preheater (7).

6. A molten salt energy storage system according to claim 1, characterized in that: The molten salt energy storage unit also includes an electric heater (15), which is located between the hot end molten salt outlet of the steam molten salt heat exchanger (9) and the hot salt inlet of the high temperature molten salt storage tank (10).

7. The molten salt energy storage system according to claim 1, characterized in that: The reflux unit includes a condenser (16), a low-pressure heater (17), a deaerator (18), and a high-pressure heater (19). The exhaust port of the low-pressure cylinder (2), the condenser (16), the low-pressure heater (17), the deaerator (18), the high-pressure heater (19), and the economizer inlet of the boiler (1) are connected in sequence through pipelines.

Images