A high-temperature calcium-based thermochemical energy storage system and a method of using the same

Abstract

The application discloses a high-temperature calcium-based thermochemical energy storage system and an application method thereof. The system comprises a kettle reactor, a CO2 storage tank and an H2O storage tank. The kettle reactor is connected with the CO2 storage tank and the H2O storage tank through pipelines. The kettle reactor is internally provided with a stirring device, a solar heat collector and a heat exchanger. The solar heat collector is externally provided with an on-off heat insulation door. The kettle reactor is internally provided with CaCO3 materials. The system has the advantages of few devices, simple structure, low cost, low energy consumption and high stability. The system has the advantages of high energy storage reaction heat exchange efficiency and high reaction conversion rate. CO2 and H2O mixed gas is used as a heat transfer medium and a reactant, and the system has the advantages of high reaction temperature and small heat loss. H2O is added in the energy release reaction, the reaction speed is higher, the conversion rate is higher, and the system can be widely applied to the field of solar high-temperature power generation.

Description

TECHNICAL FIELD

[0001] The application relates to a calcium-based thermochemical energy storage system and an application method thereof, in particular to a high-temperature calcium-based thermochemical energy storage system and an application method thereof, and belongs to the field of thermochemical energy storage systems. BACKGROUND

[0002] Solar energy is a renewable energy that is widely concerned, has the advantages of wide distribution, rich reserves and suitable scale development, and therefore, developing solar energy has important significance for realizing the "double carbon" goal.

[0003] With the gradual deepening of the "double carbon" strategy, the scale of new energy installation is continuously expanding, and the solar-thermal power station has the advantage of "storage and generation integration", and is expected to experience rapid development. The solar-thermal power station mainly includes a heat collection system, a heat transport system, a heat storage and heat exchange system and a power generation system. The main function of the heat storage system is to store light and heat energy during the day and release heat energy at night to ensure the continuous and stable operation of the power generation system.

[0004] In existing solar-thermal power stations, molten salt is mostly used as a heat storage medium. When the solar energy resource is abundant, the molten salt is heated to a high temperature (500-600 DEG C) state and then enters the storage tank for storage. The heat energy is stored in the form of sensible heat. The molten salt is usually a chlorinated salt, a carbonated salt or a nitric salt, which has a corrosive effect on the molten tank, the pipeline and other equipment, has a low heat storage density, has a high requirement for equipment insulation and is easy to decompose at high temperature. Therefore, efficient, inexpensive and safe high-temperature heat storage technology is one of the key technologies that urgently needs to be developed in the field of heat storage.

[0005] Thermochemical energy storage uses reversible chemical reactions to realize heat storage and utilization, has the advantages of high energy storage density, long energy storage period, small heat loss and high reaction temperature, can solve the problem of solar energy storage, improve the efficiency of solar heat utilization and has good development prospects. In order to make the thermochemical energy storage system operate more efficiently, it is an urgent problem to design a simple, safe and reliable reaction system with high heat and mass transfer and circulation performance. SUMMARY

[0006] The first object of the present application is to provide a high-temperature calcium-based thermochemical energy storage system, and the second object of the present application is to provide an application method of the high-temperature calcium-based thermochemical energy storage system.

[0007] Technical scheme: The high-temperature calcium-based thermochemical energy storage system comprises a kettle reactor, a CO2 storage tank and an H2O storage tank, the kettle reactor is connected with the CO2 storage tank and the H2O storage tank through pipelines respectively, the kettle reactor is provided with a stirring device, a heat collector and a heat exchanger, the solar heat collector is externally provided with an on-off type heat insulation door, and the kettle reactor is filled with CaCO3 materials.

[0008] Further, the system further comprises a high-pressure pump and a water pump, the high-pressure pump is connected with the kettle reactor and the CO2 storage tank through pipelines respectively, and the water pump is connected with the kettle reactor and the H2O storage tank through pipelines respectively.

[0009] Further, a first check valve is arranged on the pipeline connecting the high-pressure pump with the kettle reactor, and a second check valve is arranged on the pipeline connecting the water pump with the kettle reactor.

[0010] Further, the stirring device is a fan blade stirring paddle.

[0011] Further, the CaCO3 material is a powdery material, and the particle size of the CaCO3 material is less than 200 mesh.

[0012] Further, the heat exchanger is a gas heat exchanger.

[0013] Further, the materials of the high-temperature calcium-based thermochemical energy storage system are all 310S stainless steel materials.

[0014] The application method of the high-temperature calcium-based thermochemical energy storage system comprises the following steps:

[0015] (1) System preparation: start the stirring device, open the switch-type heat preservation and insulation door, the solar heat collector absorbs solar radiation heat, the temperature in the kettle reactor rises to medium temperature, the CO2 in the CO2 storage tank and the H2O in the H2O storage tank enter the kettle reactor, the H2O is vaporized by heat to form medium temperature CO2 and H2O mixed gas;

[0016] (2) Energy storage stage:

[0017] The switch-type heat preservation and insulation door is in an open state, the solar heat collector absorbs solar radiation heat, the medium temperature CaCO3 material, the medium temperature CO2 and H2O mixed gas in the kettle reactor absorb the heat energy introduced by the solar heat collector to rise in temperature, the high-temperature CaCO3 material decomposes to generate high-temperature CaO and high-temperature CO2, the medium temperature CO2 and H2O mixed gas becomes high-temperature CO2 and H2O mixed gas, the solar energy is stored in the form of chemical energy through CaO and CO2, the energy storage reaction is completed, the switch-type heat preservation and insulation door is closed, heat exchange is carried out through the heat exchanger, the CaO, CO2 and H2O in the kettle reactor are converted into medium-high temperature CaO and medium-high temperature CO2 and H2O mixed gas, and part of the surplus heat energy is sent out of the system through the heat exchanger (5), and the energy storage is completed.

[0018] (2) Energy release stage:

[0019] When the switchable thermal insulation door is in the closed state, heat exchange is carried out through a heat exchanger, converting the temperature inside the batch reactor to a medium temperature. In the batch reactor, the medium-temperature CaO material and H2O undergo a rapid thermochemical reaction to generate Ca(OH)2. Ca(OH)2 then reacts with CO2 to generate CaCO3 and H2O, releasing a large amount of heat energy. The CaCO3, H2O, excess CO2, and heat energy in the batch reactor are exchanged through the heat exchanger to maintain the medium temperature. The CaCO3, H2O, and excess CO2 in the batch reactor are converted into medium-temperature CaCO3 and a medium-temperature mixture of CO2 and H2O, respectively. The heat energy released by the thermochemical reaction is sent out of the system through the heat exchanger, and the energy release process ends.

[0020] Furthermore, the temperature of the high-temperature CO2 and H2O mixed gas is 950–980°C, the temperature of the medium-high temperature CO2 and H2O mixed gas is 700–750°C, and the temperature of the medium-temperature CO2 and H2O mixed gas is 400–600°C.

[0021] Furthermore, the temperature of the CaCO3 generated by the thermochemical reaction is controlled at 400–600°C by a heat exchanger.

[0022] Furthermore, the temperature of the high-temperature CaO is 950–980°C, the temperature of the medium-high temperature CaO is 700–750°C, and the temperature of the medium-temperature CaO is 400–600°C.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0024] (1) The present invention uses a batch reactor as an energy storage and release reactor. The stirring device in the batch reactor adopts a fan-type stirring paddle. The material is in a fluidized state, the material is in full contact with the gas, the heat exchange efficiency is high, the reaction conversion rate is high, and the agglomeration and sintering of the material will not be aggravated by high temperature, thus reducing the circulation performance of the energy storage material.

[0025] (2) This invention utilizes the reversible chemical reaction of the CaCO3 / CaO system to achieve thermal energy storage and utilization. The received solar heat drives the decomposition reaction of CaCO3, with energy stored as chemical energy in its decomposition products CaO and CO2. It has significant advantages such as high energy density, long storage period, low heat loss, and high reaction temperature, solving the problem of solar energy storage and improving the efficiency of solar thermal utilization. It can be widely applied in the field of high-temperature solar power generation.

[0026] (3) This invention uses a mixture of CO2 and H2O as the heat transfer medium. Both CO2 and H2O are triatomic gases with strong thermal radiation capabilities and high solar energy absorption efficiency. During the heat storage process, the temperature exceeds 950℃, and the partial pressure of CO2 has a relatively small impact on the conversion rate of the heat storage reaction. In the heat release reaction, the mixture of CO2 and H2O serves as a reactant, which can improve the conversion rate of the heat release reaction, and the addition of H2O can accelerate the heat release reaction rate.

[0027] (4) The storage temperature of the material after the energy storage reaction is completed is controlled at 700-750℃, so that CaO does not agglomerate and sinter. The storage temperature of the material after the energy release reaction is controlled at 400-600℃, so that CaCO3 does not decompose and the material properties are more stable.

[0028] (5) This invention uses a batch reactor, in which reactants and heat transfer media are stored simultaneously, eliminating the need for additional material storage facilities and logistics conveying devices. This approach is simple, requires fewer mechanical and power equipment, and has a low failure rate. Completing the decomposition and synthesis reactions in the same batch reactor saves on equipment investment and maintenance costs, while also reducing energy consumption and improving system stability. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the high-temperature calcium-based thermochemical energy storage system of the present invention;

[0030] Figure 2 This is a schematic diagram of the energy storage stage of the high-temperature calcium-based thermochemical energy storage system of the present invention;

[0031] Figure 3 This is a schematic diagram of the energy release stage of the high-temperature calcium-based thermochemical energy storage system of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0033] Example 1

[0034] like Figure 1As shown, the high-temperature calcium-based thermochemical energy storage system of the present invention includes a batch reactor 1, a CO2 storage tank 6, and an H2O storage tank 9. The batch reactor 1 is connected to the CO2 storage tank 6 and the H2O storage tank 9 via pipelines. The batch reactor 1 is equipped with a stirring device 2, a solar collector 3, and a heat exchanger 5. The solar collector 3 is located on the inner wall of the batch reactor 1, while the stirring device 2 and the heat exchanger 5 are both located inside the batch reactor 1. An on / off insulated door 4 is provided outside the solar collector 3. A high-pressure pump 7 is installed on the pipeline connecting the batch reactor 1 and the CO2 storage tank 6, and a first check valve 8 is installed on the pipeline connecting the high-pressure pump 7 and the batch reactor 1. A water pump 10 is installed on the pipeline connecting the batch reactor 1 and the H2O storage tank 9, and a second check valve 11 is installed on the pipeline connecting the water pump 10 and the batch reactor 1.

[0035] The system includes a stirring device 2, which employs a fan-type agitator and remains operational to thoroughly mix materials and gases within the system. An externally mounted, switchable insulated door 4 is installed on the solar collector 3 to open and close it. A gas heat exchanger 5 is used to convert and utilize the system's thermal energy while controlling the internal temperature. The batch reactor 1 contains powdered CaCO3 material with a particle size less than 200 mesh. The entire high-temperature calcium-based thermochemical energy storage system is a closed system, using a mixture of CO2 and H2O as the heat transfer medium, which participates in the reaction during the energy release phase. All materials used in the high-temperature calcium-based thermochemical energy storage system are 310S stainless steel, meeting the requirements for high-temperature and high-pressure operation.

[0036] When using:

[0037] 1. Preparations:

[0038] Start the stirring device 2, open the switch-type insulated door 4, and the solar collector 3 absorbs solar radiation heat. The temperature inside the batch reactor 1 rises to a medium temperature of 400-600℃. Start the high-pressure pump 7, open the first check valve 8, and CO2 from the CO2 storage tank 6 enters the batch reactor 1. Start the water pump 10, open the second check valve 11, and H2O from the H2O storage tank 9 enters the batch reactor 1. The H2O is heated and vaporized. Close the first check valve 8 and the second check valve 9. The system preparation work is completed.

[0039] 2. Work process:

[0040] (1) Energy storage stage:

[0041] like Figure 2As shown, the switchable insulated door 4 is in the open state, and the solar collector 3 absorbs solar radiation heat. Inside the reactor 1, a well-mixed gas mixture of 400–600°C medium-temperature CaCO3, medium-temperature CO2, and H2O absorbs the heat energy introduced by the solar collector 3. The high-temperature CaCO3 material undergoes a decomposition reaction to generate 950–980°C high-temperature CaO and high-temperature CO2. The medium-temperature CO2 and H2O mixture is transformed into a high-temperature CO2 and H2O mixture. Solar energy is stored as chemical energy through CaO and CO2. Once the energy storage reaction is complete, the switchable insulated door 4 is closed, and heat exchange occurs through the heat exchanger 5. The 950–980°C high-temperature CaO, high-temperature CO2, and H2O mixture in the system is transformed into a 700–750°C medium-high temperature CaO, medium-high temperature CO2, and H2O mixture. Some of the excess heat energy is sent out of the system through the heat exchanger 5, and the energy storage process ends.

[0042] (2) Energy release stage:

[0043] like Figure 3 As shown, the switchable thermal insulation door 4 is in the closed state, and heat exchange occurs through heat exchanger 5, converting the 700-750℃ medium-high temperature CaO, medium-high temperature CO2, and H2O mixed gas in the system into a 400-600℃ medium temperature CaCO3, medium temperature CO2, and H2O mixed gas. In the batch reactor 1, the medium temperature CaO material and medium temperature H2O undergo a rapid thermochemical reaction to generate Ca(OH)2. Ca(OH)2 then reacts thermochemically with CO2 to generate CaCO3 and H2O, releasing a large amount of heat energy. The CaCO3, H2O, excess CO2, and heat energy in the batch reactor 1 are exchanged through heat exchanger 5, converting CaCO3, H2O, and excess CO2 into medium temperature CaCO3 and a medium temperature CO2 and H2O mixed gas, respectively, maintaining a medium temperature of 400-600℃. The heat energy released by the thermochemical reaction is then discharged from the system through heat exchanger 5. The energy release process ends.

Claims

1. A high-temperature calcium-based thermochemical energy storage system, characterized in that, The system includes a batch reactor (1), a CO2 storage tank (6), and an H2O storage tank (9). The batch reactor (1) is connected to the CO2 storage tank (6) and the H2O storage tank (9) through pipelines. The batch reactor (1) is equipped with a stirring device (2), a solar collector (3), and a heat exchanger (5). The solar collector (3) is equipped with an on / off insulated door (4). The batch reactor (1) is filled with CaCO3 material. The stirring device (2) is a fan-type stirring paddle, and the heat exchanger (5) is a gas heat exchanger. A mixture of CO2 and H2O gas is used as the heat transfer medium. The application method of the high-temperature calcium-based thermochemical energy storage system is characterized by comprising the following steps: (1) System preparation: Start the stirring device (2), open the switch-type heat insulation door (4), the solar collector (3) absorbs solar radiation heat, the temperature inside the batch reactor (1) rises to medium temperature, CO2 from CO2 storage tank (6) and H2O from H2O storage tank (9) enter the batch reactor (1), H2O is heated and vaporized to form a medium temperature CO2 and H2O mixed gas; (2) Energy storage stage: When the switchable thermal insulation door (4) is in the open state, the solar collector (3) absorbs solar radiation heat. The medium-temperature CaCO3 material and the medium-temperature CO2 and H2O mixed gas in the kettle reactor (1) absorb the heat energy introduced by the solar collector (3) and rise in temperature. The high-temperature CaCO3 material undergoes a decomposition reaction to generate high-temperature CaO and high-temperature CO2. The medium-temperature CO2 and H2O mixed gas becomes a high-temperature CO2 and H2O mixed gas. Solar energy is stored in the form of chemical energy through CaO and CO2. The energy storage reaction ends. The switchable thermal insulation door (4) is closed. Heat is exchanged through the heat exchanger (5). The CaO, CO2 and H2O in the kettle reactor (1) are converted into medium-high temperature CaO and medium-high temperature CO2 and H2O mixed gas. Some of the excess heat energy is sent out of the system through the heat exchanger (5). The energy storage ends. (2) Energy release stage: The switchable thermal insulation door (4) is in the closed state. Heat exchange is carried out through the heat exchanger (5) to convert the temperature inside the batch reactor (1) to medium temperature. The medium-temperature CaO material and H2O in the batch reactor (1) undergo a rapid thermochemical reaction to generate Ca(OH)2. Ca(OH)2 reacts with CO2 to generate CaCO3 and H2O, releasing a large amount of heat energy. CaCO3, H2O, excess CO2 and heat energy in the batch reactor (1) are exchanged through the heat exchanger (5) to maintain the medium temperature. CaCO3, H2O and excess CO2 in the batch reactor (1) are converted into medium-temperature CaCO3 and medium-temperature CO2 and H2O mixed gas, respectively. The heat energy released by the thermochemical reaction is sent out of the system through the heat exchanger (5), and the energy release ends. The temperature of the high-temperature CO2 and H2O mixture is 950–980°C, the temperature of the medium-high temperature CO2 and H2O mixture is 700–750°C, and the temperature of the medium-temperature CO2 and H2O mixture is 400–600°C. The temperature of the CaCO3 generated by the thermochemical reaction is controlled at 400–600°C by a heat exchanger. The temperature of the high-temperature CaO is 950–980°C, the temperature of the medium-high temperature CaO is 700–750°C, and the temperature of the medium-temperature CaO is 400–600°C.

2. The high-temperature calcium-based thermochemical energy storage system according to claim 1, characterized in that, The system also includes a high-pressure pump (7) and a water pump (10). The high-pressure pump (7) is connected to the batch reactor (1) and the CO2 storage tank (6) via pipelines, and the water pump (10) is connected to the batch reactor (1) and the H2O storage tank (9) via pipelines.

3. The high-temperature calcium-based thermochemical energy storage system according to claim 2, characterized in that, The high-pressure pump (7) is connected to the batch reactor (1) by a first check valve (8), and the water pump (10) is connected to the batch reactor (1) by a second check valve (11).

4. The high-temperature calcium-based thermochemical energy storage system according to claim 1, characterized in that, The CaCO3 material is a powder, and the particle size of the CaCO3 material is less than 200 mesh.

5. The high-temperature calcium-based thermochemical energy storage system according to claim 1, characterized in that, The materials used in the high-temperature calcium-based thermochemical energy storage system are all 310S stainless steel.

6. The application method of the high-temperature calcium-based thermochemical energy storage system according to any one of claims 1-5, characterized in that, Includes the following steps: (1) System preparation: Start the stirring device (2), open the switch-type heat insulation door (4), the solar collector (3) absorbs solar radiation heat, the temperature inside the batch reactor (1) rises to medium temperature, CO2 from CO2 storage tank (6) and H2O from H2O storage tank (9) enter the batch reactor (1), H2O is heated and vaporized to form a medium temperature CO2 and H2O mixed gas; (2) Energy storage stage: When the switchable thermal insulation door (4) is in the open state, the solar collector (3) absorbs solar radiation heat. The medium-temperature CaCO3 material and the medium-temperature CO2 and H2O mixed gas in the kettle reactor (1) absorb the heat energy introduced by the solar collector (3) and rise in temperature. The high-temperature CaCO3 material undergoes a decomposition reaction to generate high-temperature CaO and high-temperature CO2. The medium-temperature CO2 and H2O mixed gas becomes a high-temperature CO2 and H2O mixed gas. Solar energy is stored in the form of chemical energy through CaO and CO2. The energy storage reaction ends. The switchable thermal insulation door (4) is closed. Heat is exchanged through the heat exchanger (5). The CaO, CO2 and H2O in the kettle reactor (1) are converted into medium-high temperature CaO and medium-high temperature CO2 and H2O mixed gas. Some of the excess heat energy is sent out of the system through the heat exchanger (5). The energy storage ends. (2) Energy release stage: The switchable thermal insulation door (4) is in the closed state. Heat exchange is carried out through the heat exchanger (5) to convert the temperature inside the batch reactor (1) to medium temperature. The medium-temperature CaO material and H2O in the batch reactor (1) undergo a rapid thermochemical reaction to generate Ca(OH)2. Ca(OH)2 reacts with CO2 to generate CaCO3 and H2O, releasing a large amount of heat energy. CaCO3, H2O, excess CO2 and heat energy in the batch reactor (1) are exchanged through the heat exchanger (5) to maintain the medium temperature. CaCO3, H2O and excess CO2 in the batch reactor (1) are converted into medium-temperature CaCO3 and medium-temperature CO2 and H2O mixed gas, respectively. The heat energy released by the thermochemical reaction is sent out of the system through the heat exchanger (5), and the energy release ends. The temperature of the high-temperature CO2 and H2O mixture is 950–980°C, the temperature of the medium-high temperature CO2 and H2O mixture is 700–750°C, and the temperature of the medium-temperature CO2 and H2O mixture is 400–600°C. The temperature of the CaCO3 generated by the thermochemical reaction is controlled at 400–600°C by a heat exchanger. The temperature of the high-temperature CaO is 950–980°C, the temperature of the medium-high temperature CaO is 700–750°C, and the temperature of the medium-temperature CaO is 400–600°C.

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