A drum encapsulated calcium oxide electro-thermal chemical energy storage system and method

Abstract

This invention relates to a drum-encapsulated calcium oxide electrothermal chemical energy storage system and method, comprising an energy storage tank system and an auxiliary energy storage system. The energy storage tank system includes an energy storage tank equipped with a tank tilting device and a bottom electric heating device. The energy storage tank contains an outlet pipe, an inlet pipe, and internal ribs. The auxiliary energy storage system includes a steam generator for steam-water heat exchange, an external heating steam device, a gas-liquid separator, a water storage tank, a circulating fan, a nitrogen buffer tank, an electric steam generator, a steam-water separator, a nitrogen replenishment tank, a gas-solid separator, a piston pump, and an external water supply pump. This invention employs an integrated drum-encapsulated calcium oxide energy storage reaction device and a separate one-to-many electric heating system, improving energy conversion efficiency and utilization, while also enabling off-site heat release during energy storage.

Description

Technical Field

[0001] This invention relates to the field of thermochemical energy storage technology, specifically to a roller-encapsulated calcium oxide electrothermal chemical energy storage system and method. Background Technology

[0002] Currently, thermal storage technologies are mainly divided into three types: sensible heat storage, latent heat storage, and chemical heat storage. Sensible heat storage has low heat density, significant heat loss, and a short storage cycle; phase change heat storage suffers from problems such as phase separation, material leakage, and corrosion. Compared to the first two technologies, thermochemical energy storage has significant advantages such as high energy density, high reaction temperature, and low long-term heat loss, effectively solving the problems of electrical energy conversion, storage, transmission, and high-temperature regeneration. However, current research on chemical energy storage is mostly limited to micro / small-scale experimental studies focusing on the characteristics of energy storage materials, with few complete closed-loop systems developed, and large-scale industrial applications have not yet been achieved.

[0003] Thermochemical energy storage is primarily based on a reversible thermochemical reaction. It stores and releases energy through the breaking and recombination of chemical bonds. In the storage reaction, the energy storage material absorbs heat and decomposes into two substances, which are stored separately. When energy is needed, the two substances come into full contact and react, converting the stored chemical energy into heat energy and releasing it. The volumetric and gravimetric energy storage densities of thermochemical energy storage are far higher than those of sensible heat or phase change energy storage. The energy storage carrier can be stored at room temperature for extended periods. Thermochemical energy storage can absorb renewable energy from wind, hydro, and solar power, and can also perform peak shaving and valley filling for thermal power plants, ensuring optimal and efficient use of electricity and increasing its proportion in heating, production, and daily life. Most thermochemical energy storage carriers are safe, non-toxic, inexpensive, and easy to handle, reducing the dispersion and inefficient use of fossil fuels, significantly reducing air pollutant emissions, and creating significant economic and social benefits. Among these, the Ca(OH)₂ / CaO system is a relatively ideal thermochemical energy storage system, characterized by high energy density, non-toxicity and good safety, wide availability and low cost of raw materials, and reaction at normal pressure and high temperature.

[0004] However, existing thermochemical energy storage systems mostly adopt fixed bed, fluidized bed, and screw conveyor systems. Due to the poor material flowability and low thermal conductivity, fixed beds are prone to material agglomeration and have poor heat exchange efficiency. For fluidized bed and screw conveyor systems, due to the multiple transfers of materials, the materials are prone to wear, particle refinement, and material loss, and there are also problems such as system complexity and difficulty in control. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a drum-encapsulated calcium oxide electrothermal chemical energy storage system and method. Nano-modified calcium oxide is granular and reacts with water vapor to generate granular hydrated calcium hydroxide, producing heat. The granular material has good flowability and is not prone to clumping. Low-cost or excess electrical energy is converted into chemical energy and stored in the storage tank, and then released as heat energy to provide steam or hot water to users. This system can be divided into two systems: energy storage and energy release. It can achieve long-term storage of electrical energy as chemical energy and release of heat energy at a different location. It can absorb renewable energy such as wind power, hydropower, and solar power, and can also perform peak shaving and valley filling for thermal power, making the best and most effective use of electrical energy, increasing the proportion of electrical energy in heating, production, and daily life, reducing the dispersed and inefficient use of fossil fuels, and greatly reducing the emission of air pollutants; thus creating better economic and social benefits.

[0006] The objective of this invention is achieved as follows:

[0007] A roller-encapsulated calcium oxide electrothermal-chemical energy storage system,

[0008] It includes an energy storage tank system and an energy storage auxiliary system. The energy storage tank system includes an energy storage tank, which is equipped with a tank body tilting device and a bottom electric heating device. The energy storage tank is provided with an air outlet pipe, an air inlet pipe and an inner rib plate. The bottom electric heating device is designed separately from the energy storage tank and is equipped with a vertical lifting and horizontal movement device, which can realize one-to-many tank heating.

[0009] The energy storage auxiliary system includes a steam generator for heat exchange between steam and water, a steam device for external heating, a gas-liquid separator, a water storage tank, a circulating fan, a nitrogen buffer tank, an electric steam generator, a steam-liquid separator, a nitrogen replenishment tank, a gas-solid separator, a piston pump, and an external water supply pump.

[0010] Preferably, the energy storage tank adopts a roller structure, and the energy storage tank is half-tilted by a tank tilting device, with a left and right tilting range of 180-185° and a tilting stroke rate controlled at 1-4m / min.

[0011] Preferably, the inner ribs are evenly distributed circumferentially inside the energy storage tank, and the inner ribs divide the inside of the tank into several areas.

[0012] Preferably, the air inlet pipe is arranged along the axial center of the energy storage tank, the air outlet pipe is arranged on the inner top wall of the storage tank, and the side of the air outlet pipe facing the air inlet pipe is evenly provided with through holes and is shielded by a steel plate to form a U-shaped baffle channel.

[0013] Preferably, the bottom electric heating device is located outside the tank insulation and at the bottom of the energy storage tank. The bottom electric heating device is arranged in an arc shape with an arc angle of about 150 degrees. It heats the tank wall through electromagnetic heating coils. The coils are arranged in two or more arc areas. The coils do not rotate with the tank. Instead, the heating area is controlled according to the rotation angle or stroke of the tank. The heating heat flux density is controlled at 5-8w / cm².

[0014] Preferably, the outlet pipe of the energy storage tank is connected to a gas-solid separator to separate the nitrogen or water vapor discharged from the energy storage tank from a small amount of material particles. After gravity separation, the material particles settle in the lower pipe of the separator, and then high-pressure nitrogen is periodically injected from the inlet pipe of the energy storage tank; while the gas enters the downstream steam-water heat exchange steam generator and the external heating steam device in sequence.

[0015] The external heating steam device provides steam or hot water to the outside through an external water supply pump, while the internal water vapor condenses into water, and the remaining nitrogen and condensate enter the downstream gas-liquid separator.

[0016] The water separated by the gas-liquid separator enters the water storage tank, while the nitrogen gas is connected to the nitrogen buffer tank or enters the circulating fan; the gas is pressurized by the circulating fan and then enters the inlet pipe of the energy storage tank.

[0017] The pure water stored in the water storage tank passes sequentially through a piston pump, an electric steam generator, a steam-water heat exchange steam generator, and a steam-water separator. The water separated by the steam-water separator flows back to the water storage tank by gravity through a throttling electric valve, while the separated water vapor enters the air inlet pipe of the energy storage tank.

[0018] Preferably, the electric steam generator and the steam-water heat exchange steam generator are arranged in series, and the heating source of the hydration reaction is replaced by the starting steam through temperature control; that is, when starting up, electric energy is used as the heat source for steam production, and after starting up, the superheated steam generated by the heat release of the hydration reaction is used as the heating source for steam production, thereby reducing energy consumption.

[0019] Preferably, the piston pump is a variable frequency piston pump, connected in series before the electric steam generator and the steam-water heat exchange steam generator. By utilizing the constant pressure and variable flow characteristics of the variable frequency piston pump, the flow rate and load are adjusted in a timely manner through the temperature difference control of the energy storage tank to ensure the stable progress of the hydration reaction.

[0020] A method for electrothermal chemical energy storage of calcium oxide in a drum-encapsulated container includes an electrothermal chemical energy storage process and a hydration reaction exothermic process.

[0021] Electrothermal chemical energy storage process:

[0022] The entire system is filled with nitrogen using a nitrogen-filling system. A circulating fan is then turned on to circulate the nitrogen. The bottom electric heating device and tank tilting device are gradually activated, heating the system to 550 degrees Celsius. This causes the calcium hydroxide hydrate inside the tank to decompose into calcium oxide and water vapor. The resulting water vapor mixed with nitrogen is drawn out from the tank's outlet pipe, passes through a gas-solid separator, and enters an external heating steam device. The water vapor in the mixture condenses into liquid, then passes through another gas-liquid separator. The water flows into a water storage tank, while the nitrogen continues to be pressurized by the circulating fan and enters the energy storage tank. When the material temperature exceeds 520 degrees Celsius, at which point the material has completely converted to calcium oxide, electric heating is stopped. Nitrogen continues to circulate to lower the material temperature. When the nitrogen temperature falls below the set temperature, circulation and the tank tilting device are stopped, the tank's inlet and outlet valves are closed, and nitrogen is introduced into the tank for protection.

[0023] The hydration reaction is an exothermic process:

[0024] First, the inlet and outlet valves of the energy storage tank and the tank tilting device are opened. Then, using a piston pump and an electric steam generator, the pure water in the storage tank is heated into steam. This steam then passes through a series of steam-water heat exchange steam generators and steam-water separators. Condensate is separated and returned to the storage tank, while the steam enters the energy storage tank, mixes with nitrogen, and is then discharged outside. The nitrogen and steam mixture passes through a gas-solid separator, a steam-water heat exchange steam generator, and an external heating steam device. After cooling, the condensate returns to the storage tank, and the nitrogen enters a nitrogen buffer tank, completing the steam and nitrogen replacement process. Additionally, as the steam concentration in the energy storage tank gradually increases, some of the steam undergoes an exothermic hydration reaction with the calcium oxide stored in the tank, heating the remaining steam into superheated steam. This superheated steam then passes through a gas-solid separator and a steam-water heat exchange steam generator... The generator and externally supplied steam device cool the condensate, which then enters a storage tank. Simultaneously, in the steam-water heat exchanger, superheated steam reheats the steam from the electric steam generator. The load on the electric steam generator is gradually reduced based on the outlet steam temperature until heating stops, completing the preheating process. During this process, a piston pump is needed to control the steam output, i.e., to control the pressure difference between the inlet and outlet of the storage tank, ensuring the hydration reaction proceeds normally. When the hydration reaction is complete, the outlet steam temperature of the storage tank gradually decreases. At this point, the piston pump can be gradually shut off, and the nitrogen valve opened to gradually replace the steam with nitrogen. After the piston pump is completely shut off, the circulating fan can be turned on to circulate nitrogen, simultaneously lowering the material temperature. When the nitrogen temperature gradually decreases to the set temperature, the exothermic hydration reaction process is complete.

[0025] Preferably, during the chemical energy storage and maintenance process, the inlet and outlet valves of the energy storage tank need to be closed, and a nitrogen replenishment tank should be installed to stabilize the pressure inside the tank at 0.5 bar. If off-site storage is required, the energy storage tank needs to be disconnected from the energy storage auxiliary system to enable the energy storage tank to be moved, transported, and stored off-site.

[0026] The beneficial effects of this invention are:

[0027] 1) This system realizes the integration of calcium oxide electrothermal chemical energy storage system, filling the gap in industrial applications in related fields in China;

[0028] 2) This system can make full use of cheap off-peak electricity, surplus electricity from power plants or other renewable energy sources to convert electrical energy into chemical energy for long-term storage, and convert chemical energy into thermal energy when needed to provide users with high-quality steam or hot water.

[0029] 3) This system can serve as an alternative energy source to fossil fuels, reducing emissions of pollutants such as SOx and NOx and protecting the environment;

[0030] 4) This system adopts an integrated calcium oxide energy storage reaction device with roller encapsulation and a separate one-to-many electric heating system, which improves energy conversion efficiency and utilization rate, and also realizes off-site storage and heat release of the energy storage tank. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a roller-encapsulated calcium oxide electrothermal chemical energy storage system according to the present invention.

[0032] Figure 2 This is a schematic diagram of the cross-sectional structure of the energy storage tank.

[0033] Figure 3 for Figure 2 A schematic diagram of the energy storage tank flipped 90 degrees to the left.

[0034] Figure 4 This is a schematic diagram of an energy storage tank encapsulated inside a container.

[0035] Figure 5 A schematic diagram of the process of multiple energy storage tanks participating in energy storage (unnecessary components in this process are omitted).

[0036] Figure 6 This is a schematic diagram showing the distribution structure of multiple energy storage tanks and a movable bottom heating device.

[0037] The components include: energy storage tank 1; tank body tilting device 1-1; bottom electric heating device 1-2; air outlet pipe 1-3; air inlet pipe 1-4; inner rib plate 1-5; tank body insulation 1-6; steam-water heat exchange steam generator 2; external heating steam device 3; gas-liquid separator 4; water storage tank 5; circulating fan 6; nitrogen buffer tank 7; electric steam generator 8; electric heating device of electric steam generator 8-1; steam-water separator 9; nitrogen replenishment tank 10; gas-solid separator 11; piston pump 12; and external water supply pump 13. Implementation

[0038] See Figure 1-6This invention relates to a roller-encapsulated calcium oxide electrothermal chemical energy storage system, comprising an energy storage tank system and an auxiliary energy storage system. The energy storage tank system includes an energy storage tank 1, which is equipped with a tank body tilting device 1-1 and a bottom electric heating device 1-2. The energy storage tank 1 is provided with an outlet pipe 1-3, an inlet pipe 1-4, and an inner rib plate 1-5. The auxiliary energy storage system includes a steam generator for steam-water heat exchange 2, an external heating steam device 3, a gas-liquid separator 4, a water storage tank 5, a circulating fan 6, a nitrogen buffer tank 7, an electric steam generator 8, a steam-water separator 9, a nitrogen replenishment tank 10, a gas-solid separator 11, a piston pump 12, and an external water supply pump 13.

[0039] The energy storage tank 1 adopts a roller structure. The energy storage tank 1 is half-tilted by the tank body tilting device 1-1. The tank body tilting device 1-1 is driven by a motor and gears, and the left and right tilting range is 180-185°. The tilting stroke rate is controlled at 1-4m / min.

[0040] The inner ribs 1-5 are evenly distributed circumferentially inside the energy storage tank 1. The inner ribs are firmly welded to the tank body, dividing the inside of the tank into several areas. The inner ribs 1-5 are isosceles triangles, wherein the slope of the waist side of the triangle is not less than 1:12, and the distance between the roots of the ribs is not greater than 200mm.

[0041] The air inlet pipe 1-4 is arranged along the axial center of the energy storage tank 1, and the air outlet pipe 1-3 is arranged on the inner top wall of the storage tank. The air outlet pipe 1-3 has through holes evenly opened on the side facing the air inlet pipe and is shielded by a steel plate to form a U-shaped baffle channel.

[0042] The energy storage tank 1 is equipped with tank insulation 1-6. The inner layer of the tank insulation 1-6 is wrapped with ceramic fiber paper or cotton, and the outer layer is a ceramic fiber sprayed solid bonding layer.

[0043] The bottom electric heating device 1-2 is located outside the tank insulation 1-6 and at the bottom of the energy storage tank 1. The bottom electric heating device 1-2 is arranged in an arc shape with an arc angle of about 150 degrees. It heats the tank wall through electromagnetic heating coils. The coils are arranged in two or more arc areas. The coils do not rotate with the tank. Instead, the heating area is controlled according to the rotation angle or stroke of the tank. The heating heat flux density is controlled at 5-8w / cm². The bottom electric heating device is designed separately from the energy storage tank. The bottom electric heating device 1-2 is equipped with a vertical lifting and horizontal movement device, which can realize one-to-many tank heating.

[0044] The electric steam generator 8 and the steam-water heat exchange steam generator 2 are arranged in series. The hydration reaction is replaced by the heating source of the starting steam through temperature control. That is, when it is first started, electric energy is used as the heat source for steam production. After the start-up, the superheated steam generated by the heat release of the hydration reaction is used as the heating source for steam production, thereby reducing energy consumption.

[0045] The piston pump 12 is a variable frequency piston pump, connected in series before the electric steam generator 8 and the steam-water heat exchange steam generator 2. Utilizing the constant pressure and variable flow characteristics of the variable frequency piston pump, the flow rate and load are adjusted in a timely manner through the temperature difference control of the energy storage tank to ensure the stable progress of the hydration reaction.

[0046] The nitrogen buffer tank 7 and nitrogen replenishment tank 10 can provide nitrogen protection for the system at any time, collect and replace nitrogen, and use nitrogen as a power source to recover solid particulate materials in the pipeline network.

[0047] The gas-solid separator 11, the steam-water separator 9, and the gas-liquid separator 4 are used to separate nitrogen (or water vapor) from solid particulate materials, wet steam from water droplets, and nitrogen from condensate, respectively.

[0048] The outlet pipe 1-3 of the energy storage tank 1 is connected to the gas-solid separator 11, which is used to separate the nitrogen or water vapor discharged from the energy storage tank from a small amount of material particles. After gravity separation, the material particles settle in the lower pipe of the separator. Then, high-pressure nitrogen is periodically injected from the inlet pipe 1-4 of the energy storage tank 1. The gas then enters the downstream steam-water heat exchange steam generator 2 and the external heating steam device 3 in sequence.

[0049] The external heating steam device 3 is a device that uses nitrogen and water vapor generated during the energy storage process or hydration process to transfer heat to the external system. It provides steam or hot water to the outside through the external water supply pump 13. At the same time, the internal water vapor condenses into water, and the remaining nitrogen and condensate enter the downstream gas-liquid separator 4. The water separated by the gas-liquid separator 4 enters the water storage tank 5, while the nitrogen is connected to the nitrogen buffer tank 7 or enters the circulating fan 10. After the gas is pressurized by the circulating fan 10, it enters the air inlet pipe 1-4 of the energy storage tank 1.

[0050] The pure water stored in the water storage tank 5 passes sequentially through the piston pump 12, the electric steam generator 8, the steam-water heat exchange steam generator 2, and the steam-water separator 9. The water separated by the steam-water separator 9 flows back to the water storage tank 5 by gravity through a throttling electric valve, while the separated water vapor enters the air inlet pipe 1-4 of the energy storage tank 1. The nitrogen replenishment tank 10 is connected to the nitrogen buffer tank 7, the solid storage pipe of the gas-solid separator 11, and the air inlet pipe of the energy storage tank through electromagnetic valves.

[0051] The specific implementation system and method of this invention are described as follows:

[0052] I. Pyrolysis Energy Storage System Process:

[0053] 1. First, ensure that the energy storage tank 1 is filled with half a tank of nano-modified calcium hydroxide granules, and that the energy storage tank system and auxiliary systems are filled with nitrogen to displace the air inside the system; fill the external heating steam device 3 with water, and add an appropriate amount of pure water to the water storage tank 5.

[0054] 2. Turn on the circulating fan 6 so that the nitrogen gas passes through the energy storage tank 1, the gas-solid separator 11, the external heating steam device 3, the gas-liquid separator 4 in sequence, and finally returns to the circulating fan 6.

[0055] 3. Turn on the tank tilting device 1-1 and the bottom electric heating device 1-2, and control the electric heating coils according to the tilting angle to ensure that the material is heated evenly. That is, when the tank tilts to the left 0-90 degrees, the electric heating coil on the right side remains working, and the coil on the left side turns on step by step; then pause the tilting, turn on all coils to heat at a timer until all wall temperatures reach the set overheat point of 580 degrees, stop heating, and wait for the temperature to drop to 550 degrees before starting to tilt to the right. The 0 degree, 90 degrees to the left, and 90 degrees to the right are the pause points. Repeat this left and right tilting and heating until all the calcium hydroxide granules are heated and decomposed into calcium oxide granules and water vapor.

[0056] 4. The water vapor generated in the energy storage tank 1 is mixed with nitrogen. After the particulate material is initially separated through the gas outlet pipe of the energy storage tank, it flows to the gas-solid separator 11 for gas-solid separation again. The particulate material is stored at the bottom of the separator. When the pyrolysis energy storage process is over, it is recovered by high-pressure nitrogen in the nitrogen replenishment tank 10 and returned to the energy storage tank 1.

[0057] 5. The nitrogen and water vapor mixture after gas-solid separation flows through the external heating steam device 3. The heat of the mixture is transferred to the external circulation system to provide hot water or steam to the outside. At the same time, the temperature of the mixture decreases and the water vapor is condensed into liquid water.

[0058] 6. Nitrogen and water enter the gas-liquid separator 4. The liquid water is separated and returned to the water storage tank 5. The nitrogen enters the circulating fan 6 again, and after being pressurized, it enters the energy storage tank 1.

[0059] 7. When the outlet nitrogen temperature in energy storage tank 1 reaches the set temperature, the heating of the bottom electric heating device 1-2 is stopped, and the nitrogen circulation continues. At this time, there is basically no water vapor generated. The material temperature in energy storage tank 1 is continuously reduced to the external working fluid temperature through nitrogen circulation. Then, the tank is stopped from rotating and is stopped at the 0-degree position. The circulating fan and the inlet and outlet valves of the energy storage tank are closed to complete the recovery of material particles in the gas-solid separator and end the pyrolysis energy storage system process.

[0060] II. Hydration and heat release system process:

[0061] 1. First, ensure that the energy storage tank 1 contains half a tank of nano-modified calcium oxide granules, and that the energy storage tank system and auxiliary systems are filled with nitrogen; replenish the external heating steam device to the external supply system side with water, and that the water storage tank contains an appropriate amount of pure water; and that all valves are in the appropriate positions.

[0062] 2. Turn on piston pump 12 to the lowest frequency so that water flows out of water storage tank 5, passes through piston pump 12, electric steam generator 8, steam-water heat exchange steam generator 2, steam-water separator 9 in sequence, and finally returns to water storage tank 5.

[0063] 3. Turn on the electric heating device 8-1 of the electric steam generator and gradually increase the heating power to gradually heat the water into steam. When the steam temperature at the outlet of the steam-water separator 9 reaches the set temperature, open the tank tilting device 1-1, close the valve of the steam-water separator 9 returning to the water storage tank 5, open the steam valve at the outlet of the separator, and replenish steam into the energy storage tank 1.

[0064] 4. Nitrogen in storage tank 1 is gradually replaced by steam. The mixed gas passes through gas-solid separator 11, steam generator 2 for steam-water heat exchange, steam supply device 3 for external heating, and gas-liquid separator 4. Finally, after the water vapor is condensed and separated, the remaining cooled nitrogen is filled into nitrogen buffer tank 7. During this process, calcium oxide in storage tank 1 undergoes a hydration reaction with water vapor to generate hydrated calcium hydroxide and release heat, heating the water vapor into superheated steam.

[0065] 5. After the superheated steam flows through the steam generator of the steam-water heat exchanger, it reheats the self-made steam from the water storage tank 5. At this time, the heating power of the electric heating device 8-1 of the electric steam generator should be continuously reduced until it reaches 0, based on the steam outlet temperature of the steam separator 9. After the electric heating is completed, the steam bypass valve of the steam generator of the steam-water heat exchanger should be controlled according to the steam outlet temperature of the steam separator. In addition, the working frequency of the piston pump should be controlled according to the temperature difference between the inlet and outlet of the energy storage tank 1 to adjust the system heating load. Taking the 2T energy storage tank test device as an example, the temperature difference is related to the material temperature, steam flow rate and pressure. The maximum heating load is no more than 1MW.

[0066] 6. When the temperature difference between the inlet and outlet of the energy storage tank continues to decrease, the operating frequency of the piston pump 12 can be gradually reduced until the set value is reached. Then, the piston pump 12 is stopped and the outlet valve of the steam-water separator 9 is closed. At this point, it can be confirmed that the hydration reaction is basically complete.

[0067] 7. Then, open the nitrogen buffer tank 7 and the circulating fan 6 to fill the system with nitrogen, while continuously condensing and replacing the water vapor in the system back into the water storage tank 5; at the same time, the material temperature is continuously reduced through nitrogen circulation; when the material temperature drops to the working fluid temperature, stop the tank rotation and stop it at the 0-degree position, and close the inlet and outlet valves of the circulating fan 6 and the energy storage tank 1 to complete the recovery of material particles in the gas-solid separator and end the hydration exothermic system process.

[0068] III. Nitrogen Maintenance Procedure:

[0069] After the pyrolysis energy storage system process and the hydration heat release system process are completed, the nitrogen maintenance process needs to be initiated. Allow the energy storage tank to cool naturally and control the nitrogen pressure inside the tank to be no less than 0.5 bar. When the pressure is low, the nitrogen replenishment tank needs to be opened to replenish nitrogen into the energy storage tank, ensuring that the calcium oxide or calcium hydroxide inside the energy storage tank does not come into contact with air, thus achieving long-term storage.

[0070] IV. Multi-tank parallel system:

[0071] like Figure 5 and Figure 6 This system consists of multiple energy storage tank systems working in conjunction with an auxiliary energy storage system. The auxiliary system enables the pyrolysis and hydration energy release processes of the multiple tanks. This system has two operating modes: one is tank-by-tank operation, which is no different from a single energy storage tank system, except that different tanks need to be connected for control; the other is parallel operation, which requires controlling multiple energy storage tanks to operate in parallel and synchronously. The auxiliary energy storage system should also be designed according to the overall load of the number of tanks connected in parallel.

[0072] V. One-to-many tank heating system:

[0073] In the pyrolysis energy storage system process, a bottom electric heating device is required to provide power for pyrolysis. This invention separates the energy storage tank and the bottom electric heating device into two independent components. The energy storage tank system remains essentially unchanged, except that it is encapsulated in a container for easy relocation and transportation. The bottom electric heating device uses electromagnetic induction heating and incorporates height adjustment and lateral translation mechanisms, allowing one bottom electric heating device to heat multiple energy storage tanks at different times. This design, combined with the tank-by-tank operation mode in a multi-tank parallel system, reduces investment costs while enabling off-site energy storage and release.

[0074] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A roller-encapsulated calcium oxide electrothermal-chemical energy storage system, characterized in that: It includes an energy storage tank system and an energy storage auxiliary system. The energy storage tank system includes an energy storage tank, which is equipped with a tank body tilting device and a bottom electric heating device. The energy storage tank is provided with an air outlet pipe, an air inlet pipe and an inner rib plate. The bottom electric heating device is designed separately from the energy storage tank and is equipped with a vertical lifting and horizontal movement device, which can realize one-to-many tank heating. The energy storage auxiliary system includes a steam generator for heat exchange between steam and water, a steam device for external heating, a gas-liquid separator, a water storage tank, a circulating fan, a nitrogen buffer tank, an electric steam generator, a steam-liquid separator, a nitrogen replenishment tank, a gas-solid separator, a piston pump, and an external water supply pump. The gas outlet of the energy storage tank is connected to a gas-solid separator. The gas phase outlet of the gas-solid separator is sequentially connected to a steam generator for heat exchange between steam and water, an external heating steam device, and a gas-liquid separator. The liquid phase outlet of the gas-liquid separator is connected to a water storage tank. The outlet of the water storage tank is sequentially connected to a piston pump, an electric steam generator, a steam generator for heat exchange between steam and water, and a steam-water separator. The liquid phase outlet of the steam-water separator is connected to the water storage tank. The gas phase outlet of the gas-liquid separator is connected to a nitrogen buffer tank and a circulating fan. The nitrogen replenishment tank is connected to the nitrogen buffer tank. The nitrogen replenishment tank, the circulating fan, the solid phase outlet of the gas-solid separator, and the gas phase outlet of the steam-water separator are all connected to the gas inlet pipe of the energy storage tank. The liquid phase inlet of the external heating steam device is connected to an external water supply pump.

2. A rotary packed calcium oxide electric thermal chemical energy storage system according to claim 1, wherein: The energy storage tank adopts a roller structure. The energy storage tank is half-tilted by a tank tilting device, with a left and right tilting range of 180-185° and a tilting stroke rate controlled at 1-4m / min.

3. A rotary packed calcium oxide electric thermal chemical energy storage system according to claim 1, wherein: The inner ribs are evenly distributed circumferentially inside the energy storage tank, dividing the tank into several areas.

4. A rotary packed calcium oxide electric thermal chemical energy storage system according to claim 1, wherein: The air inlet pipe is arranged along the axial center of the energy storage tank, and the air outlet pipe is arranged on the inner top wall of the storage tank. The side of the air outlet pipe facing the air inlet pipe has uniformly opened through holes and is blocked by a steel plate to form a U-shaped baffle channel.

5. The roller-encapsulated calcium oxide electrothermal-chemical energy storage system according to claim 1, characterized in that: The bottom heating device is located outside the tank insulation and at the bottom of the energy storage tank. The bottom heating device is arranged in an arc shape with an arc angle of about 150 degrees. It heats the tank wall through electromagnetic heating coils. The coils are arranged in two or more zones on the arc surface. The coils do not rotate with the tank. Instead, the heating zone is controlled according to the rotation angle or stroke of the tank. The heating heat flux density is controlled at 5-8w / cm².

6. The roller-encapsulated calcium oxide electrothermal-chemical energy storage system according to claim 1, characterized in that: The electric steam generator and the steam-water heat exchange steam generator are arranged in series. The hydration reaction is replaced by the heating source of the starting steam through temperature control. That is, when it is first started, electric energy is used as the heat source for steam production. After the start-up, the superheated steam generated by the heat release of the hydration reaction is used as the heating source for steam production, thereby reducing energy consumption.

7. The roller-encapsulated calcium oxide electrothermal-chemical energy storage system according to claim 6, characterized in that: The piston pump is a variable frequency piston pump, connected in series before the electric steam generator and the steam-water heat exchange steam generator. Utilizing the constant pressure and variable flow characteristics of the variable frequency piston pump, the flow rate and load are adjusted in a timely manner through the temperature difference control of the energy storage tank to ensure the stable progress of the hydration reaction.

8. A method for electrothermal-chemical energy storage of calcium oxide in a drum-encapsulated container, characterized in that: The drum-encapsulated calcium oxide electrothermal-chemical energy storage system according to any one of claims 1-7 includes an electrothermal-chemical energy storage process and a hydration reaction exothermic process. Electrothermal chemical energy storage process: The entire system is filled with nitrogen using a nitrogen-filling system. A circulating fan is then turned on to circulate the nitrogen. The bottom electric heating device and tank tilting device are gradually activated, heating the system to 550 degrees Celsius. This causes the calcium hydroxide hydrate inside the tank to decompose into calcium oxide and water vapor. The resulting water vapor mixed with nitrogen is drawn out from the tank's outlet pipe, passes through a gas-solid separator, and enters an external heating steam device. The water vapor in the mixture condenses into liquid, then passes through another gas-liquid separator. The water flows into a water storage tank, while the nitrogen continues to be pressurized by the circulating fan and enters the energy storage tank. When the material temperature exceeds 520 degrees Celsius, at which point the material has completely converted to calcium oxide, electric heating is stopped. Nitrogen continues to circulate to lower the material temperature. When the nitrogen temperature falls below the set temperature, circulation and the tank tilting device are stopped, the tank's inlet and outlet valves are closed, and nitrogen is introduced into the tank for protection. The hydration reaction is an exothermic process: First, the inlet and outlet valves of the energy storage tank and the tank tilting device are opened. Then, using a piston pump and an electric steam generator, the pure water in the storage tank is heated into steam. This steam then passes through a series of steam-water heat exchange steam generators and steam-water separators. Condensate is separated and returned to the storage tank, while the steam enters the energy storage tank, mixes with nitrogen, and is then discharged outside. The nitrogen and steam mixture passes through a gas-solid separator, a steam-water heat exchange steam generator, and an external heating steam device. After cooling, the condensate returns to the storage tank, and the nitrogen enters a nitrogen buffer tank, completing the steam and nitrogen replacement process. Additionally, as the steam concentration in the energy storage tank gradually increases, some of the steam undergoes an exothermic hydration reaction with the calcium oxide stored in the tank, heating the remaining steam into superheated steam. This superheated steam then passes through a gas-solid separator and a steam-water heat exchange steam generator... The generator and externally supplied steam device cool the condensate, which then enters a storage tank. Simultaneously, in the steam-water heat exchanger, superheated steam reheats the steam from the electric steam generator. The load on the electric steam generator is gradually reduced based on the outlet steam temperature until heating stops, completing the preheating process. During this process, a piston pump is needed to control the steam output, i.e., to control the pressure difference between the inlet and outlet of the storage tank, ensuring the hydration reaction proceeds normally. When the hydration reaction ends, the outlet steam temperature of the storage tank gradually decreases. At this point, the piston pump can be gradually shut off, and the nitrogen valve opened to gradually replace the steam with nitrogen. After the piston pump is completely shut off, the circulating fan can be turned on to circulate nitrogen, simultaneously lowering the material temperature. When the nitrogen temperature gradually decreases to the set temperature, the exothermic hydration reaction process is complete.

9. The method for electrothermal-chemical energy storage of calcium oxide in a drum-encapsulated container according to claim 8, characterized in that: During the maintenance of chemical energy storage, the inlet and outlet valves of the storage tank need to be closed, and a nitrogen replenishment tank should be installed to stabilize the pressure inside the tank at 0.5 bar. If off-site storage is required, the storage tank needs to be disconnected from the energy storage auxiliary system to enable the storage tank to be moved, transported, and stored off-site.

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