Multi-scene thermal power generating unit coupling fused salt heat storage system

Abstract

The utility model relates to the technical field of heat storage, and discloses a multi-scene thermal power generating unit coupling fused salt heat storage system which comprises a boiler, an outlet of the boiler is provided with one end of a second valve through a pipeline, the other end of the second valve is provided with a high-pressure cylinder, and a steam exhaust port of the high-pressure cylinder is connected with a reheating inlet of the boiler through a pipeline. A reheated outlet of the boiler is provided with one end of a fourth valve through a pipeline, the other end of the fourth valve is provided with an inlet of a medium-pressure cylinder, a steam exhaust port of the medium-pressure cylinder is provided with a low-pressure cylinder, a steam exhaust port of the low-pressure cylinder is connected with an inlet of a condenser, and a heat storage assembly is arranged outside the boiler. According to the thermal power generating unit, the three different heat storage loops can adapt to various working conditions, the operation flexibility of the thermal power generating unit is remarkably improved, energy management of the heat storage system is combined, the energy utilization rate is effectively improved, and the operation cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of heat storage, in particular to a multi-scenario thermal power unit coupled molten salt heat storage system. Background Technique

[0002] With the rapid advancement of the green transformation of China's energy and power system, the grid connection volume of renewable energy has increased rapidly. Due to the strong randomness and volatility of wind power and photovoltaic renewable energy, in order to cope with the grid load changes brought about by their large-scale grid connection, increase the flexibility of the power system, and reduce the phenomenon of abandoned wind and light, more and more large-scale thermal power units have participated in grid peak shaving;

[0003] However, due to the limitation of the minimum stable combustion load of the boiler in traditional coal-fired power plants, their peak shaving capacity can often only reach 50% of the rated load. In order to improve the flexibility of the power generation system, various energy storage methods such as pumped storage, mechanical energy storage, and battery energy storage have been developed currently. Molten salt heat storage has multiple advantages such as large capacity, long cycle, high safety, and low cost, and has become the most promising peak shaving means for thermal power units currently;

[0004] However, due to the limitations in multiple aspects such as the natural environment, energy storage capacity, and construction cost, the overall flexibility of the power generation system has always been unable to be effectively improved. Therefore, a multi-scenario thermal power unit coupled molten salt heat storage system is proposed to solve the above problems. Content of the Utility Model

[0005] In order to make up for the above deficiencies, the utility model provides a multi-scenario thermal power unit coupled molten salt heat storage system, aiming to improve the problem that the overall flexibility of the power generation system in the existing technology cannot be improved.

[0006] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0007] A multi-scenario thermal power unit coupled molten salt heat storage system includes a boiler. One end of a valve two is installed at the outlet of the boiler through a pipeline. The other end of the valve two is installed with a high-pressure cylinder. The exhaust port of the high-pressure cylinder is connected to the reheat inlet of the boiler through a pipeline. One end of a valve four is installed at the outlet of the boiler after reheat through a pipeline. The other end of the valve four is installed at the inlet of a medium-pressure cylinder. The exhaust port of the medium-pressure cylinder is installed with a low-pressure cylinder. The exhaust port of the low-pressure cylinder is connected to the inlet of a condenser. A heat storage component is arranged outside the boiler;

[0008] As a further description of the above technical solution:

[0009] The heat storage component includes a heat storage heat exchanger, which is interconnected with the boiler through pipelines. The cold molten salt inlet of the heat storage heat exchanger is installed with the outlet of the cold molten salt tank through a pipeline, and the hot molten salt outlet of the heat storage heat exchanger is installed with a molten salt pump through a pipeline;

[0010] As a further description of the above technical solution:

[0011] The outlet of the molten salt pump is installed with a hot molten salt tank through a pipeline;

[0012] As a further description of the above technical solution:

[0013] A valve one is installed on the outer periphery of the boiler. The other end of the valve one is connected to the steam inlet of the heat storage heat exchanger through a pipeline. A valve three is installed on the reheated pipeline of the boiler. The other end of the valve three is connected to the steam inlet of the heat storage heat exchanger through a pipeline;

[0014] As a further description of the above technical solution:

[0015] The outlet of the hot molten salt tank is installed with the hot molten salt inlet of the heat release heat exchanger through a pipeline. The cold molten salt outlet of the heat release heat exchanger is connected to the inlet of the cold molten salt tank through a pipeline;

[0016] As a further description of the above technical solution:

[0017] A valve five is installed at the steam outlet of the heat storage heat exchanger. The other end of the valve five is installed at the inlet of the condenser. A valve six is arranged at the steam outlet of the heat storage heat exchanger. The other end of the valve six is connected to the inlet of the low-pressure cylinder through a pipeline;

[0018] As a further description of the above technical solution:

[0019] The outlet of the condenser is connected to the first low-pressure heater, the second low-pressure heater, the third low-pressure heater, the fourth low-pressure heater, the deaerator, the feed water pump, the first high-pressure heater, the second high-pressure heater, and the third high-pressure heater in sequence through pipelines;

[0020] As a further description of the above technical solution:

[0021] Valve seven and valve eight are arranged inside the pipeline between the hot molten salt tank and the heat release heat exchanger.

[0022] The utility model has the following beneficial effects:

[0023] 1. In the utility model, by introducing a molten salt heat storage system and control valves, three different heat storage circuits are formed, which can adapt to various working conditions, flexibly respond to the changes of the power grid load, and significantly improve the operation flexibility of the thermal power unit.

[0024] 2. In the present utility model, while maintaining high-efficiency power generation, combined with the energy management of the heat storage system, the energy utilization rate is effectively improved, the operation cost is reduced, and it is especially suitable for scenarios with stable power demand, showing excellent economic benefits. Brief Description of the Drawings

[0025] Figure 1 It is a system architecture diagram of a multi-scenario thermal power unit coupled with a molten salt heat storage system proposed by the present utility model.

[0026] Legend Explanation:

[0027] 1. Boiler; 2. High-pressure cylinder; 3. Intermediate-pressure cylinder; 4. Low-pressure cylinder; 5. First high-pressure heater; 6. Second high-pressure heater; 7. Third high-pressure heater; 8. Feed water pump; 9. Deaerator; 10. First low-pressure heater; 11. Second low-pressure heater; 12. Third low-pressure heater; 13. Fourth low-pressure heater; 14. Condenser; 15. Cold molten salt tank; 16. Heat storage heat exchanger; 17. Molten salt pump; 18. Hot molten salt tank; 19. Heat release heat exchanger; 20. Valve 1; 21. Valve 2; 22. Valve 3; 23. Valve 4; 24. Valve 5; 25. Valve 6; 26. Valve 7; 27. Valve 8. Detailed Embodiment

[0028] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0029] Refer to Figure 1, an embodiment provided by the utility model: a multi-scenario thermal power unit coupled molten salt thermal energy storage system, including a boiler 1. Steam can be generated during the operation of the boiler 1. One end of a valve two 21 is installed at the outlet of the boiler 1 through a pipeline. The valve two 21 is used to control the switch of the outlet of the boiler 1. The other end of the valve two 21 is installed with a high-pressure cylinder 2. The high-pressure cylinder 2 is used to do work on the steam. The exhaust port of the high-pressure cylinder 2 is connected to the reheat inlet of the boiler 1 through a pipeline. The steam after doing work returns to the boiler 1 for reheating. One end of a valve four 23 is installed at the outlet of the boiler 1 after reheating through a pipeline. The valve four 23 is used to control the switch of the pipeline connecting the boiler 1 and the medium-pressure cylinder 3. The other end of the valve four 23 is installed at the inlet of the medium-pressure cylinder 3. The exhaust port of the medium-pressure cylinder 3 is installed with a low-pressure cylinder 4. The medium-pressure cylinder 3 and the low-pressure cylinder 4 can do further work on the steam. The exhaust port of the low-pressure cylinder 4 is connected to the inlet of a condenser 14. The steam enters the condenser 14 and can be cooled to condense into water. The outlet of the condenser 14 is connected to a first low-pressure heater 10, a second low-pressure heater 11, a third low-pressure heater 12, a fourth low-pressure heater 13, a deaerator 9, a feed water pump 8, a first high-pressure heater 5, a second high-pressure heater 6, and a third high-pressure heater 7 in sequence through pipelines. The first low-pressure heater 10, the second low-pressure heater 11, the third low-pressure heater 12, and the fourth low-pressure heater 13 can continuously heat the steam. The deaerator 9 can remove the oxygen in the condensed water. The feed water pump 8 can drive the condensed water to move towards the first high-pressure heater 5, the second high-pressure heater 6, and the third high-pressure heater 7. The first high-pressure heater 5, the second high-pressure heater 6, and the third high-pressure heater 7 can gradually heat the condensed water.

[0030] Referring to Figure 1 , a thermal energy storage component is arranged outside the boiler 1. The thermal energy storage component includes a thermal energy storage heat exchanger 16. The thermal energy storage heat exchanger 16 is connected to the boiler 1 through a pipeline. The cold molten salt inlet of the thermal energy storage heat exchanger 16 is installed at the outlet of a cold molten salt tank 15 through a pipeline. The cold molten salt tank 15 is used to store cold molten salt. The cold molten salt can enter the thermal energy storage heat exchanger 16 through a pipeline and exchange heat with the heat source here. The cold molten salt is heated by the steam extracted from the unit here. The hot molten salt outlet of the thermal energy storage heat exchanger 16 is installed with a molten salt pump 17 through a pipeline. The molten salt pump 17 can transport the hot molten salt to a hot molten salt tank 18. The outlet of the molten salt pump 17 is installed with a hot molten salt tank 18 through a pipeline. After the hot molten salt enters the hot molten salt tank 18, the heat is also stored in the hot molten salt tank 18 here. The cold molten salt tank 15 and the hot molten salt tank 18 are made of HITEC ternary molten salt, with a composition of 53% KNO3, 7% NaNO3, and 40% NaNO2 as the thermal energy storage medium. Its working temperature range is 142 - 535 °C. The hot molten salt inlet of a heat release heat exchanger 19 is installed at the outlet of the hot molten salt tank 18 through a pipeline. The cold molten salt outlet of the heat release heat exchanger 19 is connected to the inlet of the cold molten salt tank 15 through a pipeline. The hot molten salt flowing out of the hot molten salt tank 18 enters the heat release heat exchanger 19 and can transfer heat to the boiler 1.

[0031] Refer to Figure 1 Figure 1 , a valve one 20 is installed on the outer periphery of the boiler 1. The other end of the valve one 20 is connected to the steam inlet of the heat storage heat exchanger 16 through a pipeline. The valve one 20 is used to control the opening and closing of the pipeline between the boiler 1 and the heat storage heat exchanger 16. A valve three 22 is installed on the reheated pipeline of the boiler 1. The other end of the valve three 22 is connected to the steam inlet of the heat storage heat exchanger 16 through a pipeline. The valve three 22 can adjust the flow rate inside the pipeline between the boiler 1 and the heat storage heat exchanger 16. A valve five 24 is installed at the steam outlet of the heat storage heat exchanger 16. The other end of the valve five 24 is installed at the inlet of the condenser 14. Installing the valve five 24 can adjust the flow rate of the pipeline between the heat storage heat exchanger 16 and the condenser 14. A valve six 25 is provided at the steam outlet of the heat storage heat exchanger 16. The other end of the valve six 25 is connected to the inlet of the low-pressure cylinder 4 through a pipeline. The valve six 25 functions to control the opening and closing of the pipeline between the heat storage heat exchanger 16 and the low-pressure cylinder 4. Valves seven 26 and eight 27 are provided inside the pipeline between the molten salt tank 18 and the heat release heat exchanger 19. The valves seven 26 and eight 27 can control the opening and closing of the pipeline between the molten salt tank 18 and the heat release heat exchanger 19.

[0032] Working principle: During the use of this system, three different operations can be carried out according to specific usage conditions. When the power grid load fluctuates greatly, the molten salt heat storage system is required to quickly respond to the peak shaving demand of the power grid. When the power grid load decreases, as much energy as possible is quickly stored in the molten salt to achieve the delayed release of energy. During the peak power demand, the stored thermal energy can be quickly converted into electrical energy, reducing the dependence on the adjustment of the boiler load and enabling the system to more flexibly respond to load fluctuations.

[0033] Based on the above considerations, the steam flow direction of the designed loop 1 is as follows: After the steam comes out of the boiler 1, it is first divided into two paths: One path of steam, after being adjusted by the valve two 21, directly enters the high-pressure cylinder 2 to do work. The other path of steam enters the heat storage heat exchanger 16 through the valve one 20. At this time, the molten salt in the cold molten salt tank 15 is heated by the steam in the heat storage heat exchanger 16, and then is pumped into the hot molten salt tank 18 for storage by the molten salt pump 17. The steam that has completed heat release comes out of the heat storage heat exchanger 16 and enters the condenser 14 through the valve five 24. At this time, the steam is condensed, and the released heat is absorbed by the cooling water. When this loop is operating, the valves three 22 and six 25 remain closed.

[0034] In Loop 1, a part of the main steam is directly used to heat the molten salt thermal energy storage system instead of being entirely used for power generation. This operating mode is particularly effective during periods of low power demand. By storing the excess steam thermal energy in the molten salt during low-demand periods, it is possible to avoid reducing the load of Boiler 1 below the minimum stable combustion limit, thus effectively enhancing the flexibility of the thermal power unit. Ideally, adopting this loop can reduce the minimum power load of a coal-fired power plant from 30% to around 15%.

[0035] Scenario 2 aims to maximize the power generation efficiency of the power plant. While utilizing the work capacities of the high-pressure cylinder 2, intermediate-pressure cylinder 3, and low-pressure cylinder 4, part of the steam is diverted to the molten salt thermal energy storage system. Such a loop design ensures that the thermal energy of the steam is fully utilized, making it suitable for application scenarios with stable power demand and effectively improving the economic benefits of the system.

[0036] Steam flow path in Loop 2: After the main steam exits Boiler 1, it directly enters the high-pressure cylinder 2 to perform work. The steam after performing work returns to Boiler 1 for reheating. The reheated steam is again divided into two paths: One path of steam enters the intermediate-pressure cylinder 3 through the regulation of Valve Four 23 for further work. The other path of steam passes through Valve Three 22 and enters the heat storage heat exchanger 16 to heat the molten salt in the cold molten salt tank 15. Subsequently, the molten salt is pumped into the hot molten salt tank 18 for storage by the molten salt pump 17. The steam that has completed heat release exits the heat storage heat exchanger 16 and enters the low-pressure cylinder 4 through Valve Six 25 to continue performing work, maximizing the utilization of the steam energy. When this loop is operating, Valve One 20 and Valve Five 24 remain closed.

[0037] Compared with Loop 1, Loop 2 pays more attention to the multiple utilization of the thermal energy of steam during the power generation process, reducing the potential energy losses caused by direct heat storage. Through a carefully designed steam work path, the system minimizes energy losses while maintaining a high load operation of Boiler 1, and improves the overall economy through reheated steam diversion and multi-stage work, thus taking into account the energy storage function without sacrificing the energy utilization efficiency.

[0038] Scenario 3 balances energy storage and power generation efficiency well by reasonably distributing the flow direction of the reheated steam. The system can take into account peak shaving and economy under variable operating conditions, showing a more comprehensive adaptability, especially suitable for the current situation of large-scale access of fluctuating energy sources such as wind power and photovoltaic power in the power grid.

[0039] Steam flow direction in Loop 3: After the main steam comes out of the boiler 1, it directly enters the high-pressure cylinder 2 to do work. The steam after doing work returns to the boiler 1 for reheating. The reheated steam is divided into two paths: one path of steam enters the intermediate-pressure cylinder 3 to do work through the regulation of valve four 23. The other path of steam passes through valve three 22 and enters the heat storage heat exchanger 16 to heat the molten salt coming from the cold molten salt tank 15. Subsequently, the molten salt is pumped into the hot molten salt tank 18 for storage by the molten salt pump 17. The steam that has completed heat release comes out of the heat storage heat exchanger 16 and enters the condenser 14 through valve five 24, where the steam is condensed and the released heat is absorbed by the cooling water. When this loop is operating, valve one 20 and valve six 25 remain closed.

[0040] Compared with Loop 1 which focuses on peak shaving performance, Loop 3 can partially store heat during low power demand periods and partially do work during high power demand periods, achieving a balance between peak shaving capacity and economy. This loop allows part of the steam to be used for power generation by doing work, while the other part is directed to the molten salt heat storage system. When the power demand fluctuates greatly, Loop 3 can flexibly adjust the steam flow direction by adjusting the opening and closing of the valves, so as to achieve heat energy storage or power generation. This flexibility ensures that the system can not only cope with the fluctuations of the grid load but also maintain a high energy utilization efficiency.

[0041] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-scenario thermal power unit coupled molten salt thermal energy storage system, comprising a boiler (1), characterized in that: One end of a second valve (21) is installed through a pipeline at the outlet of the boiler (1), and the other end of the second valve (21) is installed with a high-pressure cylinder (2). The exhaust port of the high-pressure cylinder (2) is interconnected with the reheating inlet of the boiler (1) through a pipeline. One end of a fourth valve (23) is installed through a pipeline at the outlet of the boiler (1) after reheating, and the other end of the fourth valve (23) is installed at the inlet of an intermediate-pressure cylinder (3). The exhaust port of the intermediate-pressure cylinder (3) is installed with a low-pressure cylinder (4), and the exhaust port of the low-pressure cylinder (4) is connected to the inlet of a condenser (14). A heat storage assembly is arranged outside the boiler (1).

2. The multi-scenario thermal power unit coupled molten salt thermal energy storage system according to claim 1, wherein: The heat storage assembly includes a heat storage heat exchanger (16). The heat storage heat exchanger (16) is interconnected with the boiler (1) through a pipeline. The cold molten salt inlet of the heat storage heat exchanger (16) is installed at the outlet of a cold molten salt tank (15) through a pipeline, and the hot molten salt outlet of the heat storage heat exchanger (16) is installed with a molten salt pump (17) through a pipeline.

3. A multi-scenario thermal power unit coupled molten salt thermal energy storage system according to claim 2, characterized in that: The outlet of the molten salt pump (17) is installed with a hot molten salt tank (18) through a pipeline.

4. The multi-scenario thermal power unit coupled molten salt thermal energy storage system according to claim 2, characterized in that: A first valve (20) is installed on the outer periphery of the boiler (1), and the other end of the first valve (20) is connected to the steam inlet of the heat storage heat exchanger (16) through a pipeline. A third valve (22) is installed on the pipeline of the boiler (1) after reheating, and the other end of the third valve (22) is connected to the steam inlet of the heat storage heat exchanger (16) through a pipeline.

5. A multi-scenario thermal power unit coupled molten salt thermal energy storage system according to claim 3, characterized in that: The outlet of the hot molten salt tank (18) is installed at the hot molten salt inlet of a heat release heat exchanger (19) through a pipeline, and the cold molten salt outlet of the heat release heat exchanger (19) is connected to the inlet of the cold molten salt tank (15) through a pipeline.

6. The multi-scenario thermal power unit coupled molten salt thermal energy storage system according to claim 2, wherein: A fifth valve (24) is installed at the steam outlet of the heat storage heat exchanger (16), and the other end of the fifth valve (24) is installed at the inlet of the condenser (14). A sixth valve (25) is arranged at the steam outlet of the heat storage heat exchanger (16), and the other end of the sixth valve (25) is connected to the inlet of the low-pressure cylinder (4) through a pipeline.

7. A multi-scenario thermal power unit coupled molten salt thermal energy storage system according to claim 1, characterized in that: The outlet of the condenser (14) is connected in sequence with a first low-pressure heater (10), a second low-pressure heater (11), a third low-pressure heater (12), a fourth low-pressure heater (13), a deaerator (9), a feed water pump (8), a first high-pressure heater (5), a second high-pressure heater (6), and a third high-pressure heater (7) through pipelines.

8. A multi-scenario thermal power unit coupled molten salt thermal energy storage system according to claim 5, characterized in that: A seventh valve (26) and an eighth valve (27) are arranged inside the pipeline between the hot molten salt tank (18) and the heat release heat exchanger (19).

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