Liquid metal battery energy storage system and method based on gradient utilization of waste heat of thermal power plant

Abstract

The invention discloses a liquid metal battery energy storage system and method based on thermal power plant waste heat echelon utilization, and the system comprises a liquid metal battery pack, and a waste heat recovery module used for heating or heat preservation of the liquid metal battery pack is arranged outside the liquid metal battery pack. The waste heat recovery module and the liquid metal battery pack are respectively connected with the thermal management system, the thermal management system is connected with the thermal power generating unit through the waste heat system, in addition, the liquid metal battery pack is further connected with the thermal power generating unit through the first energy storage converter to store waste power or supply power to the thermal power generating unit, and high-temperature flue gas waste heat is used for battery starting heating; waste heat of low-temperature circulating water is used for battery heat preservation, a high-temperature-low-temperature waste heat gradient utilization mode is formed, the comprehensive utilization rate of heat energy of a thermal power plant is increased, the problems of high energy consumption and long heating time in the starting stage of the liquid metal battery are solved, and the comprehensive benefits of the thermal power coupling liquid metal battery energy storage power station are increased.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage system structure technology, specifically relating to a liquid metal battery energy storage system and method based on the cascade utilization of waste heat from thermal power plants. Background Technology

[0002] Liquid metal batteries are a new type of electrochemical energy storage technology with outstanding advantages such as long cycle life, high safety and low cost potential.

[0003] Liquid metal batteries require initial heating to ensure that the positive electrode, negative electrode, and electrolyte are all submerged in liquid form for normal charging and discharging. The normal operating temperature range for liquid metal batteries is 100-900℃. The start-up phase typically uses electric heating, which is energy-intensive and time-consuming, reducing the energy utilization rate of the battery system and limiting its economic viability. Therefore, developing rapid start-up strategies and waste heat recovery technologies will help improve the overall energy efficiency of the system. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid metal battery energy storage system and method based on the cascade utilization of waste heat from thermal power plants, so as to overcome the technical problem of high start-up energy consumption of existing liquid metal batteries.

[0005] To solve the above problems, the present invention adopts the following technical solution: A liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants includes a liquid metal battery pack, a thermal management system, a thermal power high-temperature waste heat system, a thermal power unit, a first energy storage converter, a thermal power low-temperature waste heat system, and a waste heat recovery module, wherein the waste heat recovery module is located outside the liquid metal battery pack. The thermal power units are connected to the thermal management system through a thermal power high-temperature waste heat system and a thermal power low-temperature waste heat system, respectively. The thermal management system is connected to the liquid metal battery pack and the waste heat recovery module, respectively. The liquid metal battery pack is connected to the thermal power units through the first energy storage converter.

[0006] Furthermore, it also includes a second energy storage converter, through which the liquid metal battery pack is connected to the power grid.

[0007] Furthermore, the thermal power unit is directly connected to the power grid.

[0008] Furthermore, a temperature sensor is installed inside the liquid metal battery pack, and the liquid metal battery pack is connected to the thermal management system through the temperature sensor.

[0009] Furthermore, a temperature sensor is installed inside the liquid metal battery pack, and the liquid metal battery pack is connected to the thermal management system through the temperature sensor.

[0010] Furthermore, the heat exchanger is a finned tube heat exchanger.

[0011] Furthermore, the heat pump is a water source heat pump.

[0012] Secondly, a method for operating a liquid metal battery energy storage system is provided, including: When the liquid metal battery pack is started, the thermal management system controls the high-temperature flue gas waste heat recovery system and waste heat recovery module of the thermal power unit to heat the liquid metal battery pack. After the liquid metal battery pack is started up, the thermal management system controls the thermal power unit's low-temperature circulating water waste heat recovery system and waste heat recovery module to keep the liquid metal battery pack warm. Liquid metal battery packs store excess electrical energy from thermal power units or provide electrical energy to thermal power units through the first energy storage converter, and participate in frequency regulation and peak regulation of thermal power units.

[0013] Furthermore, the liquid metal battery pack absorbs excess power from the grid or feeds power to the grid through a second energy storage converter.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants. It includes a liquid metal battery pack, a waste heat recovery module, a thermal management system, a thermal power waste heat recovery system, and a thermal power unit connected in sequence. The system uses waste heat from the thermal power plant to provide a heating source for the liquid metal battery pack, achieving a certain degree of heat energy transfer. By utilizing the waste heat from high-temperature flue gas and low-temperature circulating water from the thermal power plant, the system achieves cascade utilization of thermal power waste heat resources, forming a relatively complete internal electricity-heat cycle. This solves the problem of waste heat resource consumption and addresses the challenges of high energy consumption and long heating time during the start-up phase of the liquid metal battery, increasing the overall benefits of the thermal power-coupled liquid metal battery energy storage power station.

[0015] This invention provides an operation method for a liquid metal battery energy storage system. When the liquid metal battery needs to be started, the waste heat from the high-temperature flue gas of the thermal power plant directly heats the liquid metal battery pack. Once the battery's operating temperature range is reached, the system switches to a low-temperature circulating water waste heat recovery system to maintain the liquid metal battery pack's temperature. The thermal management system controls the battery temperature to remain within a reasonable range. During off-peak hours, the liquid metal battery absorbs excess power from the grid through an energy storage converter. During peak hours, the DC power output from the liquid metal battery is converted to AC power by the energy storage converter and fed back to the grid. Simultaneously, the liquid metal battery absorbs excess power from the thermal power unit through the energy storage converter, participating in the power plant's frequency regulation and peak shaving operations. The high-temperature flue gas waste heat is used for battery startup heating (primary utilization), and the low-temperature circulating water waste heat is used for battery insulation (secondary utilization), forming a "high-temperature-low-temperature" waste heat cascade utilization mode, improving the comprehensive utilization rate of thermal energy in the thermal power plant. Attached Figure Description

[0016] Figure 1 This is a structural diagram of a liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants, as described in an embodiment of the present invention.

[0017] In the diagram, 1 is a liquid metal battery pack; 2 is a heat exchanger; 3 is a thermal management system; 4 is a thermal power high-temperature waste heat recovery system; 5 is a thermal power unit; 6 is the first energy storage converter; 7 is the second energy storage converter; and 8 is a thermal power low-temperature waste heat recovery system. Detailed Implementation

[0018] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0021] Definitions: Liquid metal batteries are a high-temperature energy storage battery technology that uses liquid metal as electrodes and molten salt as electrolyte. Their core characteristic is that all active materials (positive electrode, negative electrode, and electrolyte) are in a liquid state at the operating temperature, naturally stratifying through density differences, thus simplifying the battery structure and improving cycle life.

[0022] Liquid metal battery energy storage systems based on the cascade utilization of waste heat from thermal power plants, such as Figure 1As shown, the system includes a liquid metal battery pack 1 and a waste heat recovery module for heating or insulating the liquid metal battery pack 1. The waste heat recovery module is connected to a thermal management system 3 via the liquid metal battery pack 1. The thermal management system 3 is connected to a thermal power high-temperature waste heat recovery system 4 and a thermal power low-temperature waste heat recovery system 8 via waste heat recovery pipelines. In addition, the liquid metal battery pack 1 is also connected to a thermal power unit 5 via a first energy storage converter 6 to store surplus electricity or supply electricity to the thermal power unit 5 and participate in the frequency regulation and peak shaving of the thermal power unit 5.

[0023] Optionally, the liquid metal battery energy storage system of the present invention is further provided with a second energy storage converter 7. The liquid metal battery pack 1 is connected to the power grid through the second energy storage converter 7 to store excess electrical energy of the power grid or to supply power to the power grid. At the same time, the thermal power unit 5 is directly connected to the power grid to supply power to the power grid.

[0024] Optionally, the external waste heat recovery module of the liquid metal battery pack 1 adopts a structure of heat exchanger 2 and heat pump connected in series. The thermal power waste heat recovery pipeline 4 is divided into a high-temperature flue gas waste heat recovery pipeline and a low-temperature circulating water waste heat recovery pipeline. Among them, the thermal power high-temperature waste heat recovery system 4 is directly connected to the heat exchanger 2 through the thermal management system 3 to provide heat for the liquid metal battery pack 1. The thermal power low-temperature circulating water waste heat recovery system 8 is connected to the heat pump through the thermal management system 3. The heat pump is connected to the heat exchanger 2 to keep the liquid metal battery pack 1 warm. The heat pump is connected in series with the heat exchanger 2 and connected to the waste heat system 8 of the thermal power plant's low-temperature circulating water. Specifically, the evaporator of the heat pump is connected to the low-temperature circulating water pipeline of the thermal power plant, and the condenser is connected to the heat exchanger 2. In addition, the heat pump is also connected to the thermal management system 3. The operation of the heat pump is controlled by the thermal management system 3. The battery temperature is monitored in real time by a temperature sensor (set inside the liquid metal battery pack 1), and the start-up and shutdown of the heat pump and the energy output are automatically adjusted.

[0025] In one optional embodiment, the heat exchanger 2 is a flue gas heat exchanger such as a finned tube heat exchanger. The high-temperature flue gas directly contacts the liquid metal battery pack 1 through the finned tube heat exchanger, rapidly heating the solid metal in the liquid metal battery pack 1 to a liquid state, thereby enabling the start-up of the liquid metal battery pack 1. In one optional implementation, a water source heat pump is selected. A heat pump is a high-efficiency energy-saving device that makes full use of low-grade heat energy. It achieves the flow of heat from a low-temperature object to a high-temperature object through a reverse circulation method, consuming a small amount of net reverse circulation work, thereby effectively utilizing low-grade heat energy that is difficult to apply to achieve the purpose of energy saving. Among them, the water source heat pump is a heat pump system that uses water as a heat source. It absorbs heat from water through the evaporator, and after being boosted by the compressor, the heat is released by the condenser to achieve the transfer of heat energy. Specifically, the evaporator of the water source heat pump is connected to the thermal power low-temperature circulating water waste heat recovery system 8 through a recovery pipeline, directly absorbing heat from the circulating water, and transferring the enhanced heat to the liquid metal battery pack 1 through the heat exchanger 2 to keep the liquid metal battery pack 1 warm.

[0026] During the heating or heat preservation phases of the liquid metal battery pack 1, the participation of the thermal management system 3 is required. That is, the thermal management system 3 is connected to the heat exchanger 2. At the same time, a temperature sensor is installed inside the liquid metal battery pack 1, and the thermal management system 3 is connected to the temperature sensor of the liquid metal battery pack 1 to collect the temperature data of the liquid metal battery pack 1.

[0027] As a preferred embodiment of the present invention, the liquid metal battery energy storage system based on thermal power waste heat coupling includes a liquid metal battery energy storage module, a thermal power plant high-temperature waste heat recovery system 4, a thermal power plant low-temperature waste heat recovery system 8, a thermal management system 3, and an intelligent control module. The liquid metal battery energy storage module includes a liquid metal battery pack 1, a heat exchanger 2, a first energy storage converter 6, and a second energy storage converter 7.

[0028] The thermal power plant's high-temperature waste heat recovery system 4 is connected to heat exchanger 2, which in turn is connected to the liquid metal battery pack 1. The thermal management module 3 controls the flow of waste heat through heat exchanger 2. When the liquid metal battery pack 1 starts up, the thermal management module 3 controls the high-temperature waste heat from the thermal power plant to pass through heat exchanger 2 to heat the liquid metal battery pack 1. When the temperature reaches the operating temperature of the liquid metal battery pack 1, the thermal management module 3 controls the thermal power plant's low-temperature circulating water waste heat system 8 to allow the low-temperature waste heat to pass through heat exchanger 2 to maintain the temperature of the liquid metal battery pack 1. The liquid metal battery pack 1 is connected to the second energy storage converter 7, which is connected to the power grid. The liquid metal battery pack 1 is also connected to the first energy storage converter 6, which is connected to the thermal power unit. The first energy storage converter 6 is controlled by an intelligent control module.

[0029] Optionally, the heat pump's drive motor is connected to the energy storage converter (first energy storage converter 6 or second energy storage converter 7) via a cable, and the energy storage converter provides electrical energy (from the power grid or thermal power unit 5). Meanwhile, the operating parameters of the heat pump are scheduled by the intelligent control module and optimized in coordination with the charging and discharging status of the liquid metal battery pack 1 and the load changes of the thermal power plant.

[0030] The present invention provides a coupled liquid metal battery energy storage system based on waste heat resources from thermal power plants. By using waste heat from thermal power plants as a heating source for liquid metal batteries, a certain degree of heat energy transfer is achieved. Through the application of waste heat from high-temperature flue gas and low-temperature circulating water from thermal power plants, the tiered utilization of waste heat resources from thermal power plants is realized, forming a relatively complete internal cycle of electricity and heat. This solves the problem of waste heat resource consumption and also solves the problems of high energy consumption and long heating time during the start-up phase of liquid metal batteries, thereby increasing the overall benefits of thermal power coupled liquid metal battery energy storage power stations.

[0031] The present invention also provides a method for operating a liquid metal battery energy storage system, comprising the following steps: When the liquid metal battery pack 1 is started, the thermal management system 3 controls the high-temperature flue gas waste heat recovery system 4 and waste heat recovery module of the thermal power unit 5 to heat the liquid metal battery pack 1. After the liquid metal battery pack 1 is started, the thermal management system 3 controls the low-temperature circulating water waste heat recovery system 8 and waste heat recovery module of the thermal power unit 5 to keep the liquid metal battery pack 1 warm. The liquid metal battery pack 1 stores excess electrical energy of the thermal power unit 5 or provides electrical energy to the thermal power unit 5 through the first energy storage converter 6, and participates in the frequency regulation and peak regulation of the thermal power unit 5.

[0032] Liquid metal battery pack 1 requires the battery to be heated first, so that its positive electrode, negative electrode, and electrolyte are all in a liquid state to allow for normal charging and discharging activities. Its normal operating temperature is 100-900℃. The start-up phase of this battery generally uses electric heating, which consumes a lot of energy and takes a long time, reducing the energy utilization rate of the battery system and limiting its economic efficiency. Thermal power plants generate electricity and also have a large surplus of heat energy. Equipping thermal power plants with energy storage can assist in frequency regulation and peak shaving of the power units. Developing waste heat utilization technology from thermal power plants can effectively improve energy efficiency, reduce emissions of greenhouse gases such as carbon dioxide, and mitigate environmental impact. Therefore, combining liquid metal battery pack 1 with thermal power unit 5 into a system, using the waste heat from thermal power as the heat source for the liquid metal battery, and utilizing the liquid metal battery to assist the thermal power unit in frequency regulation and peak shaving is a beneficial way to improve the efficiency of the liquid metal battery system and enhance the economic benefits of the thermal power plant. Coupled application of the liquid metal battery system with the thermal power plant can effectively achieve optimal economic and overall benefits.

[0033] When the liquid metal battery pack 1 needs to be started, the energy control system issues a command, and the waste heat from the high-temperature flue gas of the thermal power plant directly heats the liquid metal battery pack 1. Once the battery's operating temperature range is reached, the thermal power plant's low-temperature waste heat system is switched to maintain the liquid metal battery pack 1's temperature, and the thermal management system 3 controls the battery temperature to remain within a reasonable range. During off-peak hours, the liquid metal battery pack 1 absorbs excess power from the grid through the second energy storage converter 7. During peak hours, the DC power output from the liquid metal battery pack 1 is converted to AC power by the second energy storage converter 7 and fed back to the grid. Simultaneously, the liquid metal battery pack 1 absorbs excess power from the thermal power unit 5 through the first energy storage converter 6, and with the assistance of the intelligent control module, participates in the thermal power plant's frequency regulation and peak shaving operations.

[0034] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants, characterized in that, It includes a liquid metal battery pack (1), a thermal management system (3), a thermal power high-temperature waste heat system (4), a thermal power unit (5), a first energy storage converter (6), a thermal power low-temperature waste heat system (8), and a waste heat recovery module, wherein the waste heat recovery module is located outside the liquid metal battery pack (1); The thermal power unit (5) is connected to the thermal management system (3) through the thermal power high temperature waste heat system (4) and the thermal power low temperature waste heat system (8), respectively. The thermal management system (3) is connected to the liquid metal battery pack (1) and the waste heat recovery module, respectively. The liquid metal battery pack (1) is connected to the thermal power unit (5) through the first energy storage converter (6).

2. The liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants according to claim 1, characterized in that, It also includes a second energy storage converter (7), through which the liquid metal battery pack (1) is connected to the power grid.

3. The liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants according to claim 1, characterized in that, The thermal power unit (5) is directly connected to the power grid.

4. The liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants according to claim 1, characterized in that, The liquid metal battery pack (1) is equipped with a temperature sensor, and the liquid metal battery pack (1) is connected to the thermal management system (3) through the temperature sensor.

5. The liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants according to claim 1, characterized in that, The waste heat recovery module adopts a structure of heat exchanger (2) and heat pump connected in series.

6. The liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants according to claim 5, characterized in that, The heat exchanger (2) is a finned tube heat exchanger.

7. The liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants according to claim 5, characterized in that, The heat pump is a water source heat pump.

8. A method for operating a liquid metal battery energy storage system, characterized in that, The liquid metal battery energy storage system based on the cascade utilization of waste heat from thermal power plants according to any one of claims 1-7 includes: When the liquid metal battery pack (1) is started, the thermal management system (3) controls the high-temperature flue gas waste heat recovery system (4) and waste heat recovery module of the thermal power unit (5) to heat the liquid metal battery pack (1); After the liquid metal battery pack (1) is started, the thermal management system (3) controls the low temperature circulating water waste heat recovery system (8) and waste heat recovery module of the thermal power unit (5) to keep the liquid metal battery pack (1) warm; The liquid metal battery pack (1) stores excess electrical energy of the thermal power unit (5) or provides electrical energy to the thermal power unit (5) through the first energy storage converter (6), and participates in the frequency regulation and peak regulation of the thermal power unit (5).

9. The operation method of a liquid metal battery energy storage system according to claim 8, characterized in that, The liquid metal battery pack (1) absorbs excess power from the grid or feeds power to the grid through the second energy storage converter (7).

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