Thermochemical energy storage and release system, and energy charging method for heat storage and release material

Abstract

The present application relates to a thermochemical energy storage and release system, and an energy charging method for a heat storage and release material. The thermochemical energy storage and release system in the present application comprises: a reactor (1); and a microwave generator (2) and heat storage and release materials (3), which are arranged in the reactor (1). In the present application, microwaves directly act on the heat storage and release materials (3) to perform energy charging, thereby significantly improving the energy charging response speed, rationally reducing the energy charging temperature, and accelerating the regeneration process of thermochemical energy storage.

Description

A thermochemical energy storage and release system and a method for charging heat storage and release materials

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on March 22, 2024, with application number 202410336139.7 and invention name “A Thermochemical Energy Storage and Release System, and a Method for Charging Heat Storage and Release Materials”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the field of thermochemical energy storage and release technology, and specifically relates to a thermochemical energy storage and release system and a method for charging heat storage and release materials. Background Art

[0004] Renewable energy and waste heat recovery are key components of achieving carbon neutrality. However, addressing the intermittent nature of renewable energy and waste heat, as well as the volatility of end-user energy demand, presents significant challenges. On the demand side, many industrial processes require intermittent heating or steam production. Peak demand may occur rarely, but this requires significant investment in heat-generating equipment (such as backup electric boilers) to prepare for these periods. This also significantly increases the capacity requirements of power supply equipment.

[0005] To effectively solve these problems, using energy storage technology as an intermediate carrier is one of the effective solutions. This solution can not only balance the mismatch between energy production and energy demand, but also improve the flexibility and resilience of the energy supply chain.

[0006] Thermochemical energy storage is a commonly used energy storage technology. However, the traditional charging method, which involves electrically heating the heat storage and release materials, suffers from slow response times and low efficiency. Furthermore, the cyclic nature of the heat storage and release materials' reactions remains a major constraint on the efficiency of thermochemical energy storage systems. Summary of the Invention

[0007] Therefore, the technical problem to be solved by this application is to overcome the defects of slow charging response speed and low efficiency of thermochemical energy storage systems in the existing technology, and at the same time overcome the constraints of reaction cycle stability on the overall system efficiency from the two aspects of reactor structure design and reaction material optimization, thereby providing a thermochemical energy storage and release system and a method for charging heat storage and release materials.

[0008] To this end, this application provides the following technical solutions.

[0009] In a first aspect, the present application provides a thermochemical energy storage and release system, comprising a reactor and a microwave generator and a heat storage and release material arranged in the reactor.

[0010] Furthermore, the reactor includes a tank body, the tank body is provided with upper and lower openings, and the upper opening and the lower opening of the tank body are both provided with porous wire mesh;

[0011] The microwave generator and the heat storage and release material are both arranged in the tank body.

[0012] Furthermore, the mesh size of the porous wire mesh is not greater than twice the size of the heat storage and release material;

[0013] Optionally, the size of the heat storage and release material is greater than 5 μm, and the mesh size is 5 to 10 μm.

[0014] Furthermore, the invention further comprises a first thermocouple disposed in the tank body, wherein the first thermocouple is provided with one or more;

[0015] Optionally, the first thermocouple is a fiber optic thermocouple.

[0016] Furthermore, the heat storage and release materials are arranged in layers within the tank body, and the size of the heat storage and release materials gradually decreases from bottom to top;

[0017] Optionally, a porous baffle is provided between two adjacent layers of heat storage and release materials;

[0018] Optionally, the heat storage and release material is divided into three layers in the tank body, namely, a lower layer, a middle layer and an upper layer, the particle size of the heat storage and release material in the lower layer is 1.5 to 3 mm, the particle size of the heat storage and release material in the middle layer is 0.5 to 1.5 mm, and the particle size of the heat storage and release material in the upper layer is 0.1 to 0.5 mm;

[0019] Optionally, the height ratio of the lower layer, the middle layer and the upper layer is (1-2):(1-2):(1-2); illustratively, it can be 1:1:1, 1:2:1, 2:1:1 or 1:1:2.

[0020] Furthermore, the heat storage and release material satisfies at least one of the following conditions:

[0021] (1) The lower layer heat storage and release material includes a first thermochemical heat storage material and a first carrier;

[0022] Optionally, the mass ratio of the first thermochemical heat storage material to the first carrier is (50-65): (50-35);

[0023] Optionally, the first thermochemical heat storage material includes at least one of CaO / Ca(OH)2, MgO / Mg(OH)2, and BaO / Ba(OH)2;

[0024] Optionally, the first carrier comprises at least one of vermiculite, zeolite or silicon carbide;

[0025] (2) the middle layer heat storage and release material includes a second thermochemical heat storage material and a second carrier;

[0026] Optionally, the mass ratio of the second thermochemical heat storage material to the second carrier is (65-75):(35-25);

[0027] Optionally, the second thermochemical heat storage material includes at least one of CaO / Ca(OH)2, MgO / Mg(OH)2, and BaO / Ba(OH)2;

[0028] Optionally, the second carrier comprises at least one of vermiculite, zeolite or silicon carbide;

[0029] (3) the upper layer heat storage and release material includes a third thermochemical heat storage material and a third carrier;

[0030] Optionally, the mass ratio of the third thermochemical heat storage material to the third carrier is (75-85): (25-15);

[0031] Optionally, the third thermochemical heat storage material includes at least one of CaO / Ca(OH)2, MgO / Mg(OH)2, and BaO / Ba(OH)2.

[0032] Optionally, the third carrier comprises at least one of vermiculite, zeolite or silicon carbide;

[0033] Furthermore, at least one of the following conditions is met:

[0034] (1) The volume of heat storage material in the tank is ≤ 2 / 3 of the internal volume of the tank;

[0035] (2) A stirring device is provided in the tank body, and optionally, the stirring device is a connecting rod type mechanical stirring device;

[0036] (3) The reactor further comprises a top cover and a bottom cover, wherein the top cover is arranged at the upper opening of the tank body, and the bottom cover is arranged at the lower opening of the tank body;

[0037] The bottom cover is provided with a gas inlet, and the top cover is provided with a gas outlet;

[0038] Optionally, a second thermocouple is provided at the gas inlet, and a third thermocouple is provided at the gas outlet.

[0039] Further, it includes an electronic control panel;

[0040] The first thermocouple monitors the temperature in the reactor in real time and feeds back the temperature signal to the electronic control panel, which adjusts the output power of the microwave generator according to the received temperature signal.

[0041] In a second aspect, the present application provides a method for charging a heat storage and release material, which uses microwaves to directly heat the heat storage and release material.

[0042] Furthermore, at least one of the following conditions is met:

[0043] (1) The heat storage and release material is a material that is charged by heating and dehydration;

[0044] (2) The microwave transmission frequency is 900 MHz to 10 GHz, for example, 2.45 GHz, and the microwave output power is 0.5 to 100 kW, optionally 0.6 to 20 kW;

[0045] (3) Use renewable energy or off-peak electricity to drive the microwave generator.

[0046] Furthermore, the mesh size of the porous wire mesh is smaller than the size of the heat storage and release material.

[0047] Optionally, the first thermocouple is arranged in the gap between the blades of the stirring device. Specifically, during installation, the thermocouple is inserted into the reactor horizontally.

[0048] The thermochemical energy storage and release system controls the bed temperature at 300-600℃ during application.

[0049] Optionally, the energy release temperature is controlled at 300-400° C. to avoid excessively high temperature which is not conducive to the hydration reaction.

[0050] Optionally, the charging temperature is controlled at 400-600°C.

[0051] The system of this application is a closed system to avoid the influence of carbon dioxide. The temperature can be optionally controlled at 400-500°C for dehydration and charging. Due to the low temperature, the system material selectivity is high and the cost is low.

[0052] Optionally, a porous baffle is provided between two adjacent layers of heat storage and release materials, and the blades of the stirring device stir in each layer respectively.

[0053] In one possible design, the stirring device includes multiple sets of blades, each set of blades positioned within a corresponding layer of heat storage and release material. Optionally, the multiple sets of blades are secured by screws. To assemble the thermochemical energy storage and release system, the first set of blades can be placed in the tank, followed by the lower layer of heat storage and release material. Then, a first layer of porous baffles can be added. The second and third sets of blades can then be installed, following the same process.

[0054] The bed temperature refers to the temperature at different positions in the reactor along the radial or axial direction. The material is placed in the reactor, so the bed temperature of the reactor is basically equivalent to the temperature of the reaction material at the same position. In practical applications, in order to better monitor the temperature in the reactor, more temperature sensors need to be installed in the reactor. In the previous schematic diagram, there are not too many temperature sensors for easy understanding. For example, water vapor enters the reactor from the bottom, first contacts and reacts with the lower material, and then reacts upward. According to the temperature distribution curve measured experimentally, at a certain point in time, the temperature at different axial and radial positions in the reactor is different. Therefore, if you want to accurately monitor the temperature in the reactor, you need to set multiple temperature sensors in the axial and radial directions respectively.

[0055] Furthermore, a plurality of first thermocouples are provided.

[0056] Furthermore, the microwave generator may be a magnetron.

[0057] The microwave emission frequency and output power can be adjusted according to the corresponding energy storage application and the required amount of heat storage and release material.

[0058] The technical solution of this application has the following advantages:

[0059] 1. The thermochemical energy storage and release system of the present application includes a reactor and a microwave generator and heat storage and release material arranged in the reactor.

[0060] The present application uses microwaves to directly act on heat storage and release materials instead of using electric heating or hot air flow to charge. It uses microwave technology and volume heating methods (a method of using microwaves to uniformly heat the material within the entire reactor volume) to significantly improve the charging response speed, reasonably reduce the charging temperature, and accelerate the regeneration process of thermochemical energy storage, thereby improving the overall efficiency and flexibility of the system.

[0061] 2. The tank body is open at the top and bottom, and porous screens are installed at both the top and bottom openings of the tank body. The porous screens are designed to accommodate the heat storage and release material, ensuring that the heat storage and release material remains in the tank body during the reaction process, preventing it from falling to the bottom cover and being blown out of the tank body by the rising steam flow.

[0062] 3. The mesh size of the porous wire mesh should not be higher than twice the size of the heat storage material. Generally, the mesh size should be more than twice the size of the heat storage material particles to prevent the particles from leaking out, because it is difficult for the accumulated particles to pass through the mesh holes of similar size.

[0063] 4. The size of the heat storage and release material is greater than 5μm, and the mesh size is 5-10μm to avoid the mesh being too small to hinder the effective flow of the reaction steam, and it can also hold smaller heat storage and release materials.

[0064] 5. The first thermocouple is a fiber optic thermocouple, the material of which is insensitive to microwaves and can accurately measure the required temperature in an environment where microwaves exist.

[0065] 6. The heat storage and release materials are arranged in layers in the tank body, and the size of the heat storage and release materials gradually decreases from bottom to top.

[0066] During the energy release process of the system, water vapor enters from the gas inlet of the bottom cover and gradually rises. Therefore, the heat storage and release material in the lower layer is prone to produce a large volume expansion due to water absorption and the material is compressed and compacted, which will increase the resistance to steam flow and reduce the efficiency of the contact reaction between the steam and the unreacted material in the upper layer. Therefore, the present application adopts layered filling of the heat storage and release material in the fixed bed reactor. Large-sized particles help prevent the heat storage and release material from agglomerating in the lower and middle layers of the reactor, thereby promoting steam flow and reacting with as much heat storage and release material as possible. At the same time, the heat storage and release material with a smaller size in the upper layer has a higher specific surface area, so that it can better contact and react with water vapor and carry out heat and mass transfer.

[0067] 7. The mass ratio of the first thermochemical heat storage material and the first carrier in the lower layer is (50-65): (50-35); the mass ratio of the second thermochemical heat storage material and the second carrier in the middle layer is (65-75): (35-25); the mass ratio of the third thermochemical heat storage material and the third carrier in the upper layer is (75-85): (25-15).

[0068] Since water vapor enters the reactor from the lower layer and is absorbed by the heat storage and release material layer by layer from bottom to top to react, the steam content in the lower layer of the reactor will always be higher than that in the upper layer. If the same reaction material is used in the lower, middle and upper layers of the reactor, there will be a large gradient in the heat release and temperature of the reaction at different positions in the reactor. The content of the thermochemical heat storage material in the reactor of the present application gradually increases from bottom to top. This setting avoids the problem that the upper layer of heat storage and release material cannot react completely due to the small amount of steam, and better makes the best use of it. When the heat storage and release materials in each layer of the reactor can react more fully with the water vapor, the system can release more heat in a working cycle and the bed temperature in the reactor will be more uniform.

[0069] 8. The volume of the heat storage and release material in the tank should be ≤ 2 / 3 of the tank's internal volume. Specifically, when the tank is layered, the volume of each layer of heat storage and release material should be ≤ 2 / 3 of the tank's volume. This can mitigate the impact of the heat storage and release material's volume expansion upon water absorption on the system, for example, by reducing the degree of material compaction caused by the volume expansion of the reaction materials.

[0070] 9. A stirring device is provided inside the tank to further solve the problem of volume expansion of the heat storage material and agglomeration of reactant particles during the energy storage and release cycle (>1000 cycles).

[0071] Optionally, a connecting rod type mechanical stirring device is provided in the reactor. Since the present application can produce steam in an integrated manner without providing an additional heat exchange interface in the reactor for heat extraction (such as a heat exchange coil), a ceramic-based connecting rod type mechanical stirring device can be conveniently installed in the reactor.

[0072] 10. The thermochemical energy storage system in this application has a high thermal storage and release energy density (>300Wh / kg).

[0073] Taking calcium oxide as an example, its theoretical heat of reaction for water absorption and dehydration is high, much greater than the energy density of sensible and latent heat energy storage methods. However, in the actual application of calcium oxide water absorption and dehydration reactions, due to problems such as agglomeration of reaction materials, poor contact of reactants, reactor extrusion, and increased flow resistance, such thermochemical energy storage batteries may not be able to achieve or maintain their theoretical heat storage and release energy density over multiple cycles. This application can improve the cyclic stability of such energy storage systems, increase their energy efficiency and flexibility, making such systems more feasible and adaptable.

[0074] 11. Use renewable energy or cheap off-peak electricity to drive microwave generators, and use microwaves to directly heat the heat storage and release materials.

[0075] The thermochemical heat storage system of this application offers numerous advantages, including higher energy density (up to 500 Wh / kg, compared to 50 Wh / kg and 100 Wh / kg for sensible and latent heat storage systems, respectively). It can also be used for both short-term and long-term energy storage (i.e., daily, weekly, or quarterly timeframes) because energy losses during storage and transportation of the charged material are negligible. In contrast, sensible and latent heat storage systems are only suitable for short-term energy storage and require high insulation requirements.

[0076] In addition, the present application combines the charging, discharging and direct generation of hot steam of the thermochemical heat storage system in one reactor. In the energy extraction process of the present application, water vapor serves as both a reaction medium and a heat extraction medium to transfer heat and mass with the solid thermochemical reaction material that has completed the charging. Therefore, there is no need to set up an additional heat exchange interface for producing steam, resulting in high energy conversion efficiency.

[0077] The system of this application can also be used to upgrade the temperature grade of waste heat, making it suitable for application scenarios with higher temperatures.

[0078] The energy density of the thermochemical energy storage system in this application is greater than 300Wh / kg, the system size is small, and the charging and discharging processes in this application are completed in the same reactor, eliminating the need to transport the heat storage and discharge materials when switching between charging and discharging modes. Furthermore, the energy storage materials charged by the thermochemical reaction can be stored or transported at room temperature before discharging, without the need for extensive thermal insulation treatment.

[0079] This application can couple the charging process with renewable energy generation or smart meters to achieve the goal of saving electricity costs.

[0080] Compared to electric heating or hot air heating, microwave energy can significantly reduce the temperature required for thermochemical dehydration (e.g., by 150°C) and significantly shorten the time required for complete dehydration (e.g., by 50%). Lower dehydration temperatures and shorter dehydration times improve energy recycling efficiency and facilitate system integration and material selection.

[0081] In addition, new heat storage and release materials (for endothermic / exothermic reactions) are used in this application to further accelerate the energy storage and release process and extend the material cycle life, such as a composite material based on Ca(OH)2 and vermiculite. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0083] FIG1 is a schematic structural diagram of the thermochemical energy storage and release system of the present application;

[0084] Figure 2 is a schematic diagram of the porous wire mesh structure;

[0085] Figure 3 is a schematic diagram of the working principle of the energy release process of the thermochemical energy storage and release system;

[0086] Figure 4 is a schematic diagram of the working principle of the thermochemical energy storage and discharge system charging process;

[0087] Figure 5 shows the time required for complete dehydration of calcium hydroxide samples when they are directly heated to different temperatures by microwaves.

[0088] Figure numerals: 1-reactor; 101-tank body; 102-first porous wire mesh; 103-second porous wire mesh; 104-top cover; 105-bottom cover; 2-microwave generator; 3-heat storage and release material; 4-porous baffle; 5-stirring device; 501-blade; 6-first thermocouple; 7-gas inlet; 8-gas outlet; 9-first flange; 10-second flange; 11-electronic control panel. DETAILED DESCRIPTION

[0089] The following examples are provided to further better understand the present application, but are not limited to the best implementation mode described herein, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the scope of protection of the present application.

[0090] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0091] The preparation method of the heat storage and release material used in the embodiment of the present application is:

[0092] Calcium oxide powder and vermiculite particles are mixed at a target mass ratio. Distilled water is added to the mixture, and the mixture is stirred thoroughly to allow the calcium hydroxide solution and particles to penetrate the vermiculite's micropores. Vacuum filtration is then used to further promote the fusion of the calcium hydroxide and vermiculite. The mixture slurry is then dried in a high-temperature furnace and then dehydrated and decarbonized in a muffle furnace at 950°C to obtain calcium oxide and vermiculite composite particles.

[0093] Due to the high temperature resistance of vermiculite, this composite material can be used not only in high temperature closed systems, but also in high temperature open systems without considering the material oxidation and carbonization problems that may be encountered in high temperature open systems.

[0094] Example 1

[0095] This embodiment provides a thermochemical energy storage and release system, as shown in FIG1 and FIG2 , which includes a reactor 1 and a microwave generator 2 and heat storage and release materials arranged in the reactor 1 .

[0096] The reactor 1 includes a tank body 101 , which is opened at the top and bottom. A first porous wire mesh 102 is provided at the top opening of the tank body 101 , and a second porous wire mesh 103 is provided at the bottom opening. The microwave generator 2 and the heat storage and release material 3 are both provided in the tank body 101 .

[0097] The heat storage and release material 3 is divided into three layers in the tank body 101, namely the lower layer, the middle layer and the upper layer. A porous baffle 4 is arranged between two adjacent layers of heat storage and release material 3 to prevent the upper heat storage and release material 3 from falling. The size of the heat storage and release material 3 gradually decreases from bottom to top.

[0098] In this embodiment, the mesh size of the first porous screen 102 and the second porous screen 103 are both 5 μm. The size of the lower layer heat storage and release material is 1.5-3 mm, the size of the middle layer heat storage and release material is 0.5-1.5 mm, and the size of the upper layer heat storage and release material is 0.1-0.5 mm.

[0099] The height of the lower, middle and upper layers is 1:1:1.

[0100] In this embodiment, the lower layer heat storage and release material includes CaO / Ca(OH)2 and vermiculite, and the mass ratio of CaO / Ca(OH)2 (all converted to the mass of CaO) to vermiculite is 50:50. The middle layer heat storage and release material includes CaO / Ca(OH)2 and vermiculite, and the mass ratio of CaO / Ca(OH)2 (all converted to the mass of CaO) to vermiculite is 75:25. The upper layer heat storage and release material includes CaO / Ca(OH)2 and vermiculite, and the mass ratio of CaO / Ca(OH)2 (all converted to the mass of CaO) to vermiculite is 85:15.

[0101] The volume of each layer of heat storage and release material 3 in the tank body 101 is ≤ 2 / 3 of the internal volume of the tank body 101 in which it is located.

[0102] A stirring device 5 is provided in the tank body 101. In this embodiment, the stirring device 5 is a connecting rod type mechanical stirring device including three groups of blades 501, which are respectively provided in the lower layer, the middle layer and the upper layer of the heat storage and release material.

[0103] The thermochemical energy storage and release system further includes a first thermocouple 6 disposed in the tank body 101 ; in this embodiment, the first thermocouple 6 is a fiber optic thermocouple, and there are three first thermocouples 6 , which are respectively disposed in the upper, middle and lower layers of the tank body 101 .

[0104] The reactor 1 further includes a top cover 104 and a bottom cover 105 . The top cover is provided at the upper opening of the tank body 101 , and the bottom cover is provided at the lower opening of the tank body 101 . The bottom cover 105 is provided with a gas inlet 7 , and the top cover 104 is provided with a gas outlet 8 .

[0105] A second thermocouple is provided at the gas inlet 7 and a third thermocouple is provided at the gas outlet 8, which are used to monitor the inlet and outlet steam temperatures respectively.

[0106] In this embodiment, the tank body 101, the first porous screen 102, and the top cover 104 are connected and compressed and sealed by a first flange 9, and the tank body 101, the second porous screen 103, and the bottom cover 105 are connected and compressed and sealed by a second flange 10. The flange compression setting is to meet the requirement of using the reactor 1 in a high-pressure closed-end system (10 bar pressure).

[0107] The thermochemical energy storage and release system also includes an electronic control panel 11; the first thermocouple 6 monitors the temperature of the reactor 1 in real time and feeds back the temperature signal to the electronic control panel 11, which adjusts the output power of the microwave generator 2 according to the received temperature signal.

[0108] During the application process, the bed temperature is controlled at 300-600℃ to ensure that the entire charging and discharging process is carried out safely and effectively.

[0109] The working principle of the thermochemical energy storage and release system of this embodiment is shown in Figures 3 and 4, which is:

[0110] Charging process: Electricity drives the microwave generator to cover the entire heat storage and release material with microwaves, directly heating it with microwaves. Ca(OH)2 loses water and converts into CaO, and electrical energy is converted into chemical energy for storage.

[0111] Energy release process: Cold steam or steam preheated by waste heat (100-200℃) enters from the bottom cover of the reactor and comes into contact with the heat storage and release material. CaO undergoes a water absorption and heat release reaction, and chemical energy is converted into thermal energy. In this process, the steam will first react with the material in the lower layer of the reactor and then react with the material above layer by layer from bottom to top. The steam flow that has not reacted with the reaction material will be heated by the heat released by the water absorption and heat release reaction along its flow path, becoming superheated steam with a higher temperature, and finally flowing out from the top cover of the reactor. This part of the superheated steam can then be directly supplied to users who need steam or thermal energy.

[0112] Application Example 1

[0113] A factory involved in the distillation process requires a peak steam supply every 1-2 hours throughout the day, which poses challenges to the operation and power consumption of the main boiler. However, the use of the thermochemical energy storage system in this application can share the burden of the main boiler and significantly reduce operating and maintenance costs.

[0114] Specifically, during peak steam demand, cold steam or steam preheated with waste heat is introduced into the thermochemical energy storage system. The thermochemical energy storage material's exothermic reaction, which absorbs water and releases heat, generates superheated steam. This steam is then fed into the distillation process along with steam from the main boiler, significantly reducing the main boiler's steam production burden. After the one- to two-hour peak in steam and electricity demand, the following one- to two-hour low in steam and electricity demand allows for microwave-driven dehydration and recharging of the thermochemical energy storage material, preparing for the next peak in demand.

[0115] It’s worth noting that conventional thermochemical energy storage systems using electrical or high-temperature gas heating cannot charge in such a short time. Another advantage of this thermochemical energy storage system is that it can be used multiple times a day for storage, discharge, and steam production without requiring the need to open the cover, refuel, or move the equipment.

[0116] The thermochemical energy storage system of the present application is more flexible in transient or intermittent applications because it can be quickly charged by microwaves and body heating.

[0117] Application Example 2

[0118] A large amount of high-temperature steam is required in the papermaking industry, such as when raw materials are mixed to make pulp, and when the pulp is dehumidified, dried, and hardened into paper on a steam-heated drum. According to statistics from 2005, pulp, paper, and paperboard mills account for approximately 15% of the total energy consumption of the U.S. manufacturing industry, of which 43% is energy consumed by steam production. Currently, paper mills typically use boilers that burn biomass or fossil fuels to produce steam. In addition, since the papermaking process produces a large amount of high-temperature steam, the waste steam can be collected by condensation and recycled as waste heat. Therefore, applying the thermochemical heat storage system of this application to papermaking industry production is a potential option.

[0119] Specifically, the recovered waste steam or waste hot water can be passed into the thermochemical reaction tank of the present application, and superheated steam is generated through the water absorption and exothermic reaction, and then combined with the steam generated by the main boiler to supply to processes that require steam, such as pulp mixing and paper drying. In this way, the recycling of waste steam and waste water reduces the overall water consumption and waste of water resources. The superheated steam produced by the thermochemical energy storage system reduces the electricity and water load of the main boiler, and at the same time reduces the carbon emissions generated by the combustion of fossil fuels. However, since the papermaking process requires a continuous supply of steam, the thermochemical energy storage system used in the papermaking industry can adopt a multi-tank system. When the reaction material in one tank completes the release of energy and steam supply, it enters the microwave body heating and energy charging process, and at the same time connects to another reaction tank that has completed the charging to continue to supply energy and steam for the papermaking process.

[0120] It is worth noting that using microwave heating to dehydrate and energize the reaction materials can greatly shorten the time required. Compared with traditional electric heating or high-temperature gas heating systems, the number of reaction tanks and the amount of reaction materials used for alternating steam production are much smaller.

[0121] Application Example 3

[0122] During periods of low electricity and steam demand, the system converts cheap electricity into high-quality thermal energy and stores it (e.g., 500 degrees Celsius). During peak periods, the system directly produces high-temperature steam and supplies it to industrial processes requiring high-temperature steam (e.g., drying processes). This shifts the demand for steam and the corresponding amount of electricity used, ensuring full utilization of resources and stable operation of industrial processes.

[0123] Application Example 4

[0124] Compared to hot water storage tanks, high-temperature sensible heat storage devices, and medium- and low-temperature phase-change heat storage devices, this system has a significantly higher heat storage density (>1000 J / g), making it widely applicable to building heating and hot water supply applications with demanding space requirements. It can be used in conjunction with traditional coal-fired heating furnaces or natural gas wall-mounted boilers, utilizing off-peak electricity or renewable energy to store thermal energy at night, which can then be used to supplement hot water supply and heating throughout the day. Using this thermal storage device for heating and hot water supply can significantly reduce heating costs by taking advantage of the difference in peak and off-peak electricity prices, compared to using only electricity for heating and electric water heaters.

[0125] Test example

[0126] 1. Calcium hydroxide is heated by different heating methods:

[0127] It takes 60 minutes for a 2.5g sample of pure calcium hydroxide to be dehydrated by heating it to 500℃ in an electric high-temperature furnace.

[0128] A 2g sample of pure calcium hydroxide could not be completely dehydrated when heated to 400℃ in an electric high-temperature furnace.

[0129] 2.5g of heat storage material (wherein the mass ratio of calcium hydroxide to vermiculite is 75:25) can be completely dehydrated within 20min by heating to 400℃ through microwave.

[0130] Compared with traditional thermochemical energy storage systems that charge energy through electrically heated high-temperature furnaces or high-temperature airflow, using microwaves to directly heat and charge energy storage materials can not only increase the charging rate but also reduce the temperature required for charging, thereby greatly improving the flexibility and adaptability of the thermochemical energy storage system in this application in industrial production applications.

[0131] 2. The time required for complete dehydration of 2.5g of heat storage and release material (with a mass ratio of calcium hydroxide to vermiculite of 75:25) when heated to different temperatures by microwaves. As shown in Figure 5, the complete dehydration time is significantly shortened when the temperature is above 400°C.

[0132] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A thermochemical energy storage and release system, characterized in that: The invention comprises a reactor, a microwave generator and heat storage and release materials arranged in the reactor.

2. The thermochemical energy storage and release system according to claim 1, characterized in that: The reactor comprises a tank body, the tank body is provided with upper and lower openings, and porous wire mesh is provided at the upper opening and the lower opening of the tank body; The microwave generator and the heat storage and release material are both arranged in the tank body.

3. The thermochemical energy storage and release system according to claim 2, characterized in that: The mesh size of the porous wire mesh is not greater than twice the size of the heat storage material.

4. The thermochemical energy storage and release system according to any one of claims 1 to 3, characterized in that: The invention also includes a first thermocouple arranged in the tank body, wherein the number of the first thermocouples is one or more.

5. The thermochemical energy storage and release system according to claim 4, characterized in that: The first thermocouple is a fiber optic thermocouple.

6. The thermochemical energy storage and release system according to any one of claims 1 to 3, characterized in that: The heat storage and release materials are arranged in layers within the tank body, and the sizes of the heat storage and release materials gradually decrease from bottom to top.

7. The thermochemical energy storage and release system according to claim 6, characterized in that: The heat storage and release material is divided into three layers in the tank body: a lower layer, a middle layer and an upper layer. The size of the heat storage and release material in the lower layer is 1.5-3 mm, the size of the heat storage and release material in the middle layer is 0.5-1.5 mm, and the size of the heat storage and release material in the upper layer is 0.1-0.5 mm.

8. The thermochemical energy storage and release system according to claim 7, characterized in that: The heat storage and release material satisfies at least one of the following conditions: (1) The lower layer heat storage and release material includes a first thermochemical heat storage material and a first carrier; (2) the middle layer heat storage and release material includes a second thermochemical heat storage material and a second carrier; (3) The upper layer heat storage and release material includes a third thermochemical heat storage material and a third carrier.

9. The thermochemical energy storage and release system according to claim 8, characterized in that: At least one of the following conditions is met: (1) The mass ratio of the first thermochemical heat storage material to the first carrier is (50-65): (50-35); (2) The first thermochemical heat storage material includes at least one of CaO / Ca(OH)2, MgO / Mg(OH)2, and BaO / Ba(OH)2; (3) the first carrier comprises at least one of vermiculite, zeolite or silicon carbide; (4) The mass ratio of the second thermochemical heat storage material to the second carrier is (65-75): (35-25); (5) The second thermochemical heat storage material includes at least one of CaO / Ca(OH)2, MgO / Mg(OH)2, and BaO / Ba(OH)2; (6) the second carrier comprises at least one of vermiculite, zeolite or silicon carbide; (7) The mass ratio of the third thermochemical heat storage material to the third carrier is (75-85): (25-15); (8) The third thermochemical heat storage material includes at least one of CaO / Ca(OH)2, MgO / Mg(OH)2, and BaO / Ba(OH)2; (9) The third carrier includes at least one of vermiculite, zeolite or silicon carbide.

10. The thermochemical energy storage and release system according to any one of claims 1 to 3, characterized in that: At least one of the following conditions is met: (1) The volume of heat storage material in the tank is ≤ 2 / 3 of the internal volume of the tank; (2) A stirring device is provided in the tank; (3) The reactor further comprises a top cover and a bottom cover, wherein the top cover is arranged at the upper opening of the tank body, and the bottom cover is arranged at the lower opening of the tank body; The bottom cover is provided with a gas inlet, and the top cover is provided with a gas outlet.

11. The thermochemical energy storage and release system according to claim 10, characterized in that: A second thermocouple is provided at the gas inlet. and / or, A third thermocouple is provided at the gas outlet.

12. The thermochemical energy storage and release system according to any one of claims 1 to 3, characterized in that: Also included is an electronic control panel; The first thermocouple monitors the temperature in the reactor in real time and feeds back the temperature signal to the electronic control panel, which adjusts the output power of the microwave generator according to the received temperature signal.

13. A method for charging a heat storage material, characterized in that: Microwaves are used to directly heat the heat storage and release materials.

14. The heat storage and release material charging method according to claim 13, characterized in that: At least one of the following conditions is met: (1) The heat storage and release material is a material that is charged by heating and dehydration; (2) The microwave transmission frequency is 900MHz to 10GHz, and the microwave output power is 0.5 to 100kW; (3) Use renewable energy or off-peak electricity to drive the microwave generator.

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