A molten salt heat storage coupled coal-fired power plant salt system and working method

Abstract

The present invention discloses a molten salt heat storage coupled coal-fired power plant salt making system and a working method. The present invention utilizes the exhaust steam of a medium-pressure cylinder to heat the molten salt to a liquid state, thereby realizing the salt making process of the molten salt heat storage system during initial commissioning and salt replenishment during operation, replacing the original salt making process using electricity, and transforming from utilizing the terminal product of the coal-fired power plant - electric energy to utilizing the intermediate product - exhaust steam of the medium-pressure cylinder, thereby reducing the cost of salt making. In the long run, the operating economy of the molten salt heat storage system can be greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of molten salt heat storage, and in particular relates to a molten salt heat storage coupled coal-fired power plant salt system and a working method. Background Art

[0002] Against the backdrop of increasingly prominent environmental pollution and energy crisis, achieving large-scale utilization of renewable energy and improving energy efficiency have become the focus of global attention. Through energy storage technology, not only can the absorption capacity of new energy power generation be improved, but also the comprehensive utilization efficiency of energy can be improved, peak loads can be reduced and valley loads can be filled, and the cascade utilization of energy can be truly realized. Among them, heat storage technology has the advantages of large energy storage capacity, long storage cycle, low cost, safe and reliable operation, and no pollution emissions. Compared with other energy storage technologies, heat storage is more suitable for the needs of large-scale energy storage. Heat storage technology is expected to usher in greater development space and opportunities in clean heating, thermal power peak regulation, and clean energy absorption. Molten salt heat storage technology has a flexible heat storage method and is currently the first choice for large-scale medium and high temperature heat storage technology. It is an important technology to increase the proportion of clean energy power generation. Molten salt materials have the advantages of making the heat storage system have a wide range of applications, green environmental protection, safety and stability, and can be widely used in thermal power flexibility transformation, clean heating, renewable energy absorption and other fields.

[0003] Molten salt heat storage is a sensible heat storage technology that uses the temperature difference of molten salt during the heating or cooling process to achieve thermal energy storage. The molten salt always remains in liquid form throughout the entire operating temperature range. The melting point of HTS molten salt, a low-temperature molten salt material that is widely used in China, is about 142°C, and the optimal operating temperature range is recommended to be 250~550°C. The melting point of molten salt used in general industry is relatively high. In order to avoid freezing, the entire heat transfer and heat storage system requires strict insulation and heating measures. In the process of continuous circulation of heat storage and heat release, liquid molten salt will leak to varying degrees in the heat storage tank and the circulation pipeline, and liquid molten salt needs to be replenished regularly.

[0004] At present, the salt-making process of the molten salt heat storage system during initial commissioning and operation is mostly heated by electricity. Figure 1 However, electricity, as the end product of coal-fired power plants, has a high cost and the economic efficiency of thermal storage operation is low. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a molten salt heat storage coupled coal-fired power plant salt system and working method, which can not only adjust the power generation load, but also use high-temperature steam as an intermediate product in the power generation process of the coal-fired power plant, and the cost of use is lower than that of electricity, thereby greatly improving the operating economy of the molten salt heat storage system.

[0006] In order to achieve the above-mentioned purpose, a molten salt heat storage coupled coal-fired power plant salt system includes a medium-pressure cylinder, the exhaust steam outlet of the medium-pressure cylinder is connected to a salt feed tank through a pipeline, the drain outlet of the salt feed tank is connected to a condenser through a pipeline, and the molten salt outlet of the salt feed tank is connected to a molten salt heater in a heat storage and release circulation system through a pipeline.

[0007] The heat storage and release circulation system includes a molten salt heater, the molten salt outlet of the molten salt heater is connected to a high-temperature molten salt tank, the molten salt outlet of the high-temperature molten salt tank is connected to a heating station, the low-temperature molten salt outlet of the heating station is connected to a low-temperature molten salt tank, and the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt heater.

[0008] A second booster pump is arranged on the pipeline between the low-temperature molten salt tank and the molten salt heater.

[0009] A third booster pump is provided on the pipeline between the high-temperature molten salt tank and the heating station.

[0010] A stop valve and an electric regulating valve are provided on the pipeline between the medium-pressure cylinder and the salt supply tank.

[0011] A pressure reducing valve is installed on the pipeline between the salt feed tank and the condenser.

[0012] A first booster pump is arranged on the pipeline between the salt replenishing tank and the molten salt heater.

[0013] A working method of a molten salt heat storage coupled with a coal-fired power plant salt system, comprising the following steps:

[0014] The exhaust steam from the medium-pressure cylinder heats the solid molten salt in the salt feed tank to liquid state, and then sends it to the molten salt heater in the heat storage and release circulation system. The drain water after the exhaust steam from the medium-pressure cylinder heats the molten salt is sent to the condenser.

[0015] The molten salt in the salt replenishment tank is mixed with the molten salt in the low-temperature molten salt tank and then enters the molten salt heater. The heated high-temperature molten salt is stored in the high-temperature molten salt tank. The high-temperature molten salt enters the heating station to supply heat to the outside and then turns into low-temperature molten salt and enters the low-temperature molten salt tank, completing the molten salt heat storage and release cycle.

[0016] Compared with the prior art, the present invention utilizes the exhaust steam from the medium-pressure cylinder to heat the molten salt to a liquid state, thereby realizing the salt-making process for the initial commissioning and salt replenishment of the molten salt heat storage system during operation, replacing the original salt-making process using electricity, and transforming from utilizing the terminal product of the coal-fired power plant - electric energy to utilizing the intermediate product - exhaust steam from the medium-pressure cylinder, thereby reducing the cost of salt-making. In the long run, it can greatly improve the operating economy of the molten salt heat storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the structural diagram of the existing system;

[0018] Figure 2 is a system structure diagram of the present invention;

[0019] Among them, 1. Medium pressure cylinder, 2. Salt feeding tank, 3. Condenser, 4. Stop valve, 5. Electric regulating valve, 6. Pressure reducing valve, 7. Molten salt heater, 8. High temperature molten salt tank, 9. Heating station, 10. Low temperature molten salt tank, 11. First booster pump, 12. Second booster pump, 13. Third booster pump. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] See also Figure 2 A molten salt heat storage coupled coal-fired power plant salt system includes a medium-pressure cylinder 1, the exhaust outlet of the medium-pressure cylinder 1 is connected to the salt supplement tank 2 through a pipeline, the drain outlet of the salt supplement tank 2 is connected to the condenser 3 through a pipeline, and the molten salt outlet of the salt supplement tank 2 is connected to the molten salt heater 7 in the heat storage and release cycle system through a pipeline. A stop valve 4 and an electric regulating valve 5 are arranged on the pipeline between the medium-pressure cylinder 1 and the salt supplement tank 2. A pressure reducing valve 6 is arranged on the pipeline between the salt supplement tank 2 and the condenser 3. A first booster pump 11 is arranged on the pipeline between the salt supplement tank 2 and the molten salt heater 7.

[0022] The heat storage and release circulation system includes a molten salt heater 7, the molten salt outlet of the molten salt heater 7 is connected to a high-temperature molten salt tank 8, the molten salt outlet of the high-temperature molten salt tank 8 is connected to a heating station 9, the low-temperature molten salt outlet of the heating station 9 is connected to a low-temperature molten salt tank 10, and the molten salt outlet of the low-temperature molten salt tank 10 is connected to the molten salt heater 7. A second booster pump 12 is provided on the pipeline between the low-temperature molten salt tank 10 and the molten salt heater 7. A third booster pump 13 is provided on the pipeline between the high-temperature molten salt tank 8 and the heating station 9.

[0023] See also Figure 2 , a working method of a molten salt heat storage coupled with a coal-fired power plant salt system, comprising the following steps:

[0024] After the exhaust steam of the medium-pressure cylinder 1 heats the solid molten salt in the salt supplement tank 2 to liquid state, it enters the molten salt heater 7 in the heat storage and release circulation system through the first booster pump 11; the drain water after the exhaust steam of the medium-pressure cylinder 1 heats the molten salt enters the condenser 3 through the pressure reducing valve 6; the molten salt in the salt supplement tank 2 passes through the first booster pump 11 and the molten salt in the low-temperature molten salt tank 10 and then passes through the second booster pump 12 to mix and enter the molten salt heater 7, the heated high-temperature molten salt is stored in the high-temperature molten salt tank 8, the high-temperature molten salt in the high-temperature molten salt tank 8 enters the heating station 9 through the third booster pump 13 to supply heat to the outside and then becomes low-temperature molten salt and enters the low-temperature molten salt tank 10, completing the molten salt storage and release cycle.

[0025] The present invention converts the heat source of molten salt from existing electric energy to the thermal energy of high-temperature steam. According to the physical properties of the molten salt material, the exhaust steam of the medium-pressure cylinder is selected to heat the molten salt until it is completely melted, thereby meeting the demand for molten salt when putting into operation or replenishing the molten salt, and improving the operating economy of the molten salt heat storage system.

Claims

1. A working method of a molten salt heat storage coupled with a coal-fired power plant salt system, characterized in that: The salt molten salt system comprises a medium-pressure cylinder (1), the exhaust steam outlet of the medium-pressure cylinder (1) is connected to a salt replenishing tank (2) via a pipeline, the drain outlet of the salt replenishing tank (2) is connected to a condenser (3) via a pipeline, and the molten salt outlet of the salt replenishing tank (2) is connected to a molten salt heater (7) in a heat storage and release circulation system via a pipeline; A second booster pump (12) is provided on the pipeline between the low-temperature molten salt tank (10) and the molten salt heater (7); The working method includes the following steps: The exhaust steam of the medium-pressure cylinder (1) heats the solid molten salt in the salt supplement tank (2) to a liquid state, and then sends the heated molten salt to a molten salt heater (7) in a heat storage and release circulation system. The drain water after the exhaust steam of the medium-pressure cylinder (1) heats the molten salt is sent to a condenser (3); The molten salt in the salt replenishment tank (2) is mixed with the molten salt in the low-temperature molten salt tank (10) and then enters the molten salt heater (7). The heated high-temperature molten salt is stored in the high-temperature molten salt tank (8). The high-temperature molten salt enters the heating station (9) to supply heat to the outside and then becomes low-temperature molten salt and enters the low-temperature molten salt tank (10), thus completing the molten salt heat storage and release cycle. The heat storage and release circulation system comprises a molten salt heater (7), the molten salt outlet of the molten salt heater (7) is connected to a high-temperature molten salt tank (8), the molten salt outlet of the high-temperature molten salt tank (8) is connected to a heating station (9), the low-temperature molten salt outlet of the heating station (9) is connected to a low-temperature molten salt tank (10), and the molten salt outlet of the low-temperature molten salt tank (10) is connected to the molten salt heater (7); A stop valve (4) and an electric regulating valve (5) are provided on the pipeline between the medium-pressure cylinder (1) and the salt replenishing tank (2); A pressure reducing valve (6) is provided on the pipeline between the salt replenishing tank (2) and the condenser (3).

2. The working method of a molten salt heat storage coupled with a coal-fired power plant salt system according to claim 1 is characterized in that: A third booster pump (13) is provided on the pipeline between the high-temperature molten salt tank (8) and the heating station (9).

3. The working method of a molten salt heat storage coupled with a coal-fired power plant salt system according to claim 1 is characterized in that: A first booster pump (11) is provided on the pipeline between the salt replenishment tank (2) and the molten salt heater (7).

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