Porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material and preparation method thereof

Abstract

The invention belongs to the technical field of thermochemical energy storage materials, and relates to a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material and a preparation method thereof. Drying the calcium hydroxide powder, and granulating to obtain wet calcium hydroxide particles; drying again to obtain calcium hydroxide particles; the preparation method comprises the following steps: fully grinding and mixing glass powder, polyvinylpyrrolidone and bamboo powder, adding deionized water, and uniformly stirring to obtain a coating stock solution; dripping the coating stock solution into the calcium hydroxide particles while drying the calcium hydroxide particles, and coating the particles; after coating is completed, drying continues to be conducted, and dried particles are obtained; and calcining the dried particles, and cooling to room temperature to obtain the porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material. The mass fraction of the glass powder, the bamboo powder and the polyvinylpyrrolidone is 80-100 parts; 2.5 to 7.5 parts of bamboo powder; and 2.5 to 7.5 parts of polyvinylpyrrolidone. The problems of material pulverization and low thermal conductivity which cannot be effectively solved by a traditional granulation technology are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermochemical energy storage materials, and in particular relates to a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material and a preparation method thereof. Background Art

[0002] The industrial-scale application of thermochemical energy storage materials based on the CaO / Ca(OH)2 system currently faces several major challenges. First, during repeated storage / release cycles, the particulate material at the bottom of the reactor bed is prone to mechanical degradation, manifested in particle wear, pulverization, and subsequent compaction. This will lead to reduced bed permeability and the formation of a non-uniform flow distribution of the reaction vapor, which seriously hinders the gas-solid reaction kinetics. Second, the inherent low thermal conductivity of calcium-based materials limits the efficient transfer of heat throughout the bed during both endothermic hydrolysis and exothermic hydration processes, making it difficult to meet the requirements of high storage / release cycle stability and rapid storage / release.

[0003] To address these issues, existing approaches primarily utilize a granulation process involving molding, drying, and calcination to prepare thermochemical energy storage material particles. However, traditional granulation techniques cannot effectively address the issues of material pulverization and low thermal conductivity. Therefore, there is an urgent need to develop novel thermochemical energy storage material particles and their preparation methods. These could significantly improve the material's mechanical strength, thermal conductivity, and gas-solid reaction efficiency, thereby ensuring stable and efficient operation in industrial-scale applications. Summary of the Invention

[0004] The purpose of the present invention is to provide a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material and a preparation method thereof, which solves the problem that traditional granulation technology cannot effectively solve the problem of material pulverization and low thermal conductivity.

[0005] The present invention is achieved through the following technical solutions: The present invention discloses a method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material, comprising the following steps: After drying the calcium hydroxide powder, granulating it to obtain calcium hydroxide wet granules; drying it again to obtain calcium hydroxide granules, which will serve as the subsequent coating matrix; The glass powder, polyvinyl pyrrolidone and bamboo powder are fully ground and mixed to obtain a mixed powder; deionized water is added and stirred to obtain a coating stock solution; While drying the calcium hydroxide particles, the coating stock solution is dripped into the particles to coat them; After coating is completed, continue drying to obtain dried particles; The dried particles are calcined and cooled to room temperature to obtain a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material.

[0006] Furthermore, the calcium hydroxide powder is dried, specifically at 150-200° C. for 1 hour.

[0007] Further, drying is performed again, specifically, drying in a blast drying oven at 200° C. for 8 hours.

[0008] Furthermore, the glass powder, bamboo powder and polyvinyl pyrrolidone are calculated in mass fractions as follows: 80-100 parts of glass powder; 2.5-7.5 parts of bamboo powder and 2.5-7.5 parts of polyvinyl pyrrolidone.

[0009] Furthermore, while drying the calcium hydroxide particles, a coating stock solution is dripped into the particles to coat them, specifically as follows: Place the calcium hydroxide particles in a blower coating machine and turn on 80-110°C hot air to dry the particles; During the operation of the coating machine, the coating solution is evenly dripped several times to coat the particles.

[0010] Furthermore, the calcination adopts a staged heating method, specifically: First, heat to 350-400℃ and keep warm for 1 hour to pyrolyze bamboo powder to form pores; then heat to 450-500℃ and keep warm for 1 hour to pyrolyze polyvinyl pyrrolidone to form pores; continue to heat to 570℃ and keep warm for 1-2 hours.

[0011] The temperature was then raised from room temperature at a rate of 8-12°C / min.

[0012] The mixture was then cooled to room temperature at a cooling rate of 2-3°C / min.

[0013] The invention also discloses a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material prepared by the preparation method.

[0014] Furthermore, the mechanical strength of the porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material is greater than 30 N, and the bed thermal conductivity is greater than or equal to 0.2 W / (m·K).

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a preparation method of a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material. The method comprises the following steps: drying calcium hydroxide powder and then granulating the powder to obtain calcium hydroxide wet granules. This is because when a disc granulator is used for granulation, the lower the material moisture is, the more uniform the particle size of the granules produced is. The powder is dried again to obtain calcium hydroxide granules, thereby increasing the strength of the calcium hydroxide granules and serving as a subsequent coating matrix. When the disc granulator is used to directly coat glass powder and bamboo powder, it is difficult to coat the surfaces of the particles uniformly due to their different densities. Therefore, the invention uses glass powder as a shell raw material, polyvinyl pyrrolidone as a binder, and bamboo powder as a pore-forming agent. The three materials are fully ground and mixed to obtain a mixed powder. Deionized water is added, stirred evenly, and then a coating stock solution is prepared, which can coat the glass powder and bamboo powder relatively uniformly. While drying the calcium hydroxide particles, a coating solution is dripped into the particles to coat the particles; after coating, the particles are further dried to obtain dried particles; the dried particles are calcined, bamboo powder and PVP are pyrolyzed to form pores, and micron-sized pores are formed inside the particles to strengthen the gas-solid reaction. After cooling to room temperature, a highly thermally conductive porous shell is finally formed, which facilitates rapid mass transfer and intercepts pulverized materials. By coating the calcium hydroxide particles in a highly thermally conductive porous shell, on the one hand, the heat conduction between the particles can be enhanced, the thermal conductivity of the material can be improved, and the rapid transfer of heat in the bed during the storage / release process can be promoted; on the other hand, the pulverized material can be effectively intercepted, the mechanical strength of the material can be improved, and the problem of crushing, pulverization, and further compaction of the material in the lower part of the reactor bed can be prevented, thereby improving the efficiency of the gas-solid reaction and the stability of the storage / release cycle; the directional preparation of stable pores is achieved, and the pores serve as the inlet and outlet channels for the reaction gas to promote the rapid and stable progress of the gas-solid reaction.

[0016] Furthermore, during the shell calcination stage, the temperature is increased at a heating rate of 8-12°C / min: first, the temperature is increased to 350-400°C and kept for 1 hour, and the bamboo powder is pyrolyzed to form pores; then the temperature is increased to 450-500°C and kept for 1 hour, and polyvinyl pyrrolidone is pyrolyzed to form pores; the temperature is further increased to 570°C to achieve glass powder sintering, and then cooled to room temperature at a cooling rate of 2-3°C / min. The corresponding pore-forming agents are removed within a specific range to avoid the simultaneous decomposition of the two pore-forming agents, bamboo powder and PVP, so as to control the gas release rate and protect the structural integrity of the embryo.

[0017] The present invention also discloses a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material prepared by the method. The formation of the porous cage-shaped shell not only enhances the heat conduction between particles, but also intercepts the powdered material after multiple cycles. Compared with industrial-grade calcium hydroxide particles, the mechanical strength is improved by more than 22% after the storage / release cycle, and the thermal conductivity of the bed is improved by more than 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1This is a process mechanism diagram of a method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material of the present invention; Figure 2 This is a photo of particles of the calcium oxide / calcium hydroxide heat storage material prepared in Example 1 after ten cycles; Figure 3 This is a photo of the particles of the calcium oxide / calcium hydroxide heat storage material prepared in Example 2 after ten cycles. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following is a further detailed description with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0020] Therefore, the detailed description of the embodiment of the present invention provided in the following figures is not intended to limit the scope of the claimed invention, but is merely an illustration of a selected embodiment of the present invention. All other embodiments derived by those skilled in the art based on the figures and embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "comprises", "includes" or any other variations are intended to cover non-exclusive inclusion, so that a process, element, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to the process, element, method, article or apparatus.

[0022] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0023] Example 1 The present invention discloses a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material, and the specific preparation process is as follows: Step 1, placing 500 g of calcium hydroxide powder with a particle size of 200 mesh in a blast drying oven and drying at 200° C. for 1 hour to obtain dry calcium hydroxide powder; Step 2: Granulate using a disc granulator to obtain calcium hydroxide wet granules with a diameter of 3 mm.

[0024] Step 3: Place the wet calcium hydroxide particles obtained in step 2 in a forced air drying oven and dry them at 200° C. for 8 hours to obtain calcium hydroxide particles, which are used as the subsequent coating matrix.

[0025] Step 4: Use 200-mesh glass powder as the shell material, polyvinyl pyrrolidone (PVP) as the binder, and bamboo powder as the pore-forming agent. Add 100 g of glass powder, 5 g of PVP (K30), and 5 g of bamboo powder to the mixture in a planetary ball mill. Grind thoroughly for 30 minutes to obtain a uniform mixed powder.

[0026] Step 5: Place the mixed powder obtained in step 4 in a stirring tank, add 100 ml of deionized water, and stir evenly to obtain a coating stock solution.

[0027] Step 6: Place the calcium hydroxide particles obtained in step 3 in a blower coating machine, turn on the 100°C hot air to dry the particles, and use a dropper to evenly drop the coating solution several times (10 times) during the operation of the coating machine to coat the particles.

[0028] Step 7: After step 6, continue to open the 100°C hot air and continue drying for 1 hour to obtain dried particles.

[0029] Step 8. Place the dried particles in a tubular furnace and heat them from room temperature to 350°C at a heating rate of 10°C / min and keep them warm for 1 hour. Then heat them to 450°C and keep them warm for 1 hour. Continue heating them to 570°C and keep them warm for 1 hour. Then cool them to room temperature at a cooling rate of 2°C / min to finally obtain a calcium oxide / calcium hydroxide heat storage material with a porous and highly thermally conductive shell.

[0030] The calcium oxide / calcium hydroxide heat storage material prepared in this embodiment was tested. The average mechanical strength of the particles was 36.4 N, and the thermal conductivity of the particle bed was 0.24 W / (m·K). Figure 2 shown.

[0031] like Figure 1 As shown in the figure, glass powder, polyvinyl pyrrolidone (PVP) and bamboo powder are mixed into a coating solution. When Ca (OH)2 particles are coated multiple times, PVP plays a dispersing and bonding role, allowing the glass powder and other substances to be evenly attached to the surface of the Ca (OH)2 particles; during the drying process, the solvent (deionized water) evaporates, and the coating layer structure is initially formed.

[0032] The calcination step is crucial for establishing the porous cage structure. Bamboo powder contains a large amount of organic matter, which undergoes thermal decomposition during calcination (such as decomposition of cellulose), generating gaseous emissions and leaving behind porous channels. The glass powder softens and melts at high temperatures, forming a "cage-like" shell together with undecomposed residues. Upon cooling, the shell solidifies, forming a porous cage-like structure enclosing the Ca(OH)2 core.

[0033] The porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material prepared by the present invention undergoes an endothermic reaction (Ca(OH)2 hydrolysis): At high temperatures, the Ca(OH)2 core undergoes a hydrolysis reaction, absorbing chemical energy for storage.

[0034] Heat storage (CaO hydration): When the temperature is low and there is water vapor, CaO reacts with water vapor to release heat.

[0035] Anti-powdering effect, specifically due to: Traditional CaO / Ca (OH)2 thermal storage materials are prone to pulverization and breakage due to repeated volume expansion and contraction during circulation (Ca (OH)2 decomposition → CaO volume reduction, CaO hydration → Ca (OH)2 volume expansion), resulting in a decrease in reaction activity.

[0036] The porous cage-like coating has a certain toughness and structural strength, which can constrain the volume change of the core: During the hydration reaction, the irregular expansion and fragmentation of Ca (OH)2 is restricted; at the same time, the porous structure provides a diffusion channel for water vapor, ensuring contact with the inner core CaO / Ca (OH)2, without affecting the efficiency of the heat storage cycle reaction, and achieving synergy between anti-powdering and efficient heat storage.

[0037] In summary, the key mechanism of the present invention is: a porous cage-like shell plus a Ca(OH)2 / CaO core structure is constructed through coating and calcination, the shell is used to constrain volume changes to prevent pulverization, and the reversible reaction of the core CaO-Ca(OH)2 is relied upon to achieve a heat storage / release cycle.

[0038] Example 2 The present invention discloses a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material, and the specific preparation process is as follows: Step 1, placing 500 g of calcium hydroxide powder with a particle size of 200 mesh in a blast drying oven and drying at 180° C. for 1 hour to obtain dry calcium hydroxide powder; Step 2: Granulate using a disc granulator to obtain calcium hydroxide wet granules with a diameter of 3 mm.

[0039] Step 3: Place the wet calcium hydroxide particles obtained in step 2 in a forced air drying oven and dry them at 200° C. for 8 hours to obtain calcium hydroxide particles, which are used as the subsequent coating matrix.

[0040] Step 4: Use 200-mesh glass powder as the shell material, polyvinyl pyrrolidone (PVP) as the binder, and bamboo powder as the pore-forming agent. (Polyvinyl pyrrolidone can also be used as a pore-forming agent.) Add 7.5 g of PVP (K30) and 7.5 g of bamboo powder to 100 g of glass powder in a planetary ball mill and thoroughly grind for 30 minutes to obtain a uniform mixed powder.

[0041] Step 5: Place the mixed powder obtained in step 4 in a stirring tank, add 100 ml of deionized water, and stir evenly to obtain a coating stock solution.

[0042] Step 6: Place the calcium hydroxide particles in a blower coating machine and turn on 110°C hot air to dry the particles. While the coating machine is running, use a dropper to evenly add the coating solution multiple times (10 times) to coat the particles.

[0043] Step 7: After step 6 is completed, continue to open the 100°C hot air, and continue to dry for 1 hour after the coating is completed to obtain dried particles.

[0044] Step 8. Place the dried particles in a tubular furnace, heat from room temperature to 400°C at a heating rate of 8°C / min and keep warm for 1 hour, then heat to 500°C and keep warm for 1 hour, and continue to heat to 570°C and keep warm for 2 hours; then cool to room temperature at a cooling rate of 3°C / min, and finally obtain a calcium oxide / calcium hydroxide heat storage material with a porous and highly thermally conductive shell.

[0045] The calcium oxide / calcium hydroxide heat storage material prepared in this embodiment was tested. The average mechanical strength of the particles was 33.40N, and the thermal conductivity of the particle bed was 0.23W / (m·K). Figure 3 shown.

[0046] Example 3 The present invention discloses a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material, and the specific preparation process is as follows: Step 1, weigh 500g of calcium hydroxide powder, place it in an electric blast drying oven, set the temperature to 200°C, and dry it for 1 hour to obtain dry calcium hydroxide powder; Step 2: Granulate using a disc granulator to obtain calcium hydroxide wet granules with a diameter of 3 mm.

[0047] Step 3: Place the wet calcium hydroxide particles obtained in step 2 in an electric blast drying oven, set the temperature to 200° C., and dry for 8 hours to obtain calcium hydroxide particles as the subsequent coating matrix.

[0048] Step 4: Weigh 80 g of glass powder, 2.5 g of polyvinyl pyrrolidone and 3 g of bamboo powder, place them in a planetary ball mill, and ball mill for 45 minutes to obtain a uniform mixed powder.

[0049] Step 5: Place the mixed powder obtained in step 4 in a stirring tank, add 150 ml of deionized water, and stir for 45 minutes to obtain a coating stock solution.

[0050] Step 6: Place the calcium hydroxide particles obtained in step 3 in a blower coating machine, turn on the 100°C hot air to dry the particles, and use a dropper 4 times to evenly drop the coating solution into the particles during the operation of the coating machine to coat the particles.

[0051] Step 7: After step 6, continue to open the hot air at 100°C and dry for 45 minutes to obtain dried particles.

[0052] Step 8: Place the dried particles in a tube furnace and heat them from room temperature to 350°C at a heating rate of 12°C / min and keep them warm for 1 hour. Then, heat them to 450°C and keep them warm for 1 hour. Then, heat them to 570°C and keep them warm for 2 hours. Then, cool them to room temperature at a cooling rate of 3°C / min to obtain a calcium oxide / calcium hydroxide heat storage material with a porous and highly thermally conductive shell.

[0053] The calcium oxide / calcium hydroxide heat storage material prepared in this example was tested. The average mechanical strength of the particles was 36.7N, and the thermal conductivity of the particle bed was 0.24W / (m·K).

[0054] Example 4 The present invention discloses a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material, and the specific preparation process is as follows: Step 1, weigh 500g of calcium hydroxide powder, place it in an electric blast drying oven, set the temperature to 200°C, and dry it for 1 hour to obtain dry calcium hydroxide powder; Step 2: Granulate the calcium hydroxide using a disc granulator to obtain calcium hydroxide wet granules with a diameter of 2.5 mm.

[0055] Step 3: Place the wet calcium hydroxide particles obtained in step 2 in an electric blast drying oven, set the temperature to 200° C., and dry for 8 hours to obtain calcium hydroxide particles with a diameter of 2.5 mm, which serve as the subsequent coating matrix; Step 4: Weigh 90 g of glass powder, 2.5 g of polyvinyl pyrrolidone and 2.5 g of bamboo powder, place them in a planetary ball mill, and ball mill for 40 minutes to obtain a uniform mixed powder.

[0056] Step 5: Place the mixed powder obtained in step 4 in a stirring tank, add 180 ml of deionized water, and stir for 35 minutes to obtain a coating stock solution. Step 6: Place the calcium hydroxide particles obtained in step 3 in a blower coater, turn on the hot air at 100°C, rotate the coater at a speed of 12 rpm, and evenly drip 25 ml of the coating solution every 2.5 minutes for a total of 6 times to coat the particles.

[0057] Step 7: After step 6, continue to open the hot air at 80°C and dry for 40 minutes to obtain dried particles.

[0058] Step 8. Place the dried particles in a tubular furnace, heat from room temperature to 400°C at a heating rate of 8°C / min and keep warm for 1 hour, then heat to 450°C and keep warm for 1 hour, and continue to heat to 570°C and keep warm for 2 hours; then cool to room temperature at a cooling rate of 3°C / min, and finally obtain a calcium oxide / calcium hydroxide heat storage material with a porous and highly thermally conductive shell.

[0059] The calcium oxide / calcium hydroxide heat storage material prepared in this example was tested. The average mechanical strength of the particles was 37.1 N, and the thermal conductivity of the particle bed was 0.25 W / (m·K).

[0060] Example 5 The present invention discloses a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material, and the specific preparation process is as follows: Step 1, weigh 500g of calcium hydroxide powder, place it in an electric blast drying oven, set the temperature to 200°C, and dry it for 1 hour to obtain dry calcium hydroxide powder; Step 2: Granulate the calcium hydroxide using a disc granulator to obtain calcium hydroxide wet granules with a diameter of 2.5 mm.

[0061] Step 3: Place the wet calcium hydroxide particles obtained in step 2 in an electric blast drying oven, set the temperature to 200° C., and dry for 8 hours to obtain calcium hydroxide particles with a diameter of 2.5 mm, which serve as the subsequent coating matrix; Step 4: Weigh 85 g of glass powder, 6 g of polyvinyl pyrrolidone and 6 g of bamboo powder, place them in a planetary ball mill, and ball mill for 40 minutes to obtain a uniform mixed powder.

[0062] Step 5: Place the mixed powder obtained in step 4 in a stirring tank, add 180 ml of deionized water, and stir for 35 minutes to obtain a coating stock solution. Step 6: Place the calcium hydroxide particles obtained in step 3 in a blower coater, turn on the hot air at 100°C, rotate the coater at a speed of 12 rpm, and evenly drip 25 ml of the coating solution every 2.5 minutes for a total of 6 times to coat the particles.

[0063] Step 7: After step 6, continue to open the hot air at 110°C and dry for 40 minutes to obtain dried particles.

[0064] Step 8. Place the dried particles in a tubular furnace, heat from room temperature to 400°C at a heating rate of 8°C / min and keep warm for 1 hour, then heat to 450°C and keep warm for 1 hour, and continue to heat to 570°C and keep warm for 2 hours; then cool to room temperature at a cooling rate of 3°C / min, and finally obtain a calcium oxide / calcium hydroxide heat storage material with a porous and highly thermally conductive shell.

[0065] The calcium oxide / calcium hydroxide heat storage material prepared in this example was tested. The average mechanical strength of the particles was 33.6 N, and the thermal conductivity of the particle bed was 0.23 W / (m·K).

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material, characterized in that: The following processes are included: After drying the calcium hydroxide powder, granulating it to obtain calcium hydroxide wet granules; drying it again to obtain calcium hydroxide granules, which will serve as the subsequent coating matrix; The glass powder, polyvinyl pyrrolidone and bamboo powder are fully ground and mixed to obtain a mixed powder; deionized water is added and stirred to obtain a coating stock solution; While drying the calcium hydroxide particles, the coating stock solution is dripped into the particles to coat them; After coating is completed, continue drying to obtain dried particles; The dried particles are calcined and cooled to room temperature to obtain a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material.

2. The method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 1, characterized in that: The calcium hydroxide powder is dried, specifically by drying at 150-200° C. for 1 hour.

3. The method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 1, characterized in that: The product was dried again, specifically in a blast drying oven at 200° C. for 8 hours.

4. The method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 1, characterized in that: The glass powder, bamboo powder and polyvinyl pyrrolidone are calculated in mass fractions as follows: 80-100 parts of glass powder; 2.5-7.5 parts of bamboo powder and 2.5-7.5 parts of polyvinyl pyrrolidone.

5. The method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 1, characterized in that: While drying the calcium hydroxide particles, the coating stock solution is dripped into the particles to coat them, specifically: Place the calcium hydroxide particles in a blower coating machine and turn on 80-110°C hot air to dry the particles; During the operation of the coating machine, the coating solution is evenly dripped several times to coat the particles.

6. The method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 1, characterized in that: Calcination adopts a staged heating method, specifically: First, heat to 350-400℃ and keep warm for 1 hour to pyrolyze bamboo powder to form pores; then heat to 450-500℃ and keep warm for 1 hour to pyrolyze polyvinyl pyrrolidone to form pores; continue to heat to 570℃ and keep warm for 1-2 hours.

7. The method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 1, characterized in that: The temperature was raised from room temperature at a rate of 8-12°C / min.

8. The method for preparing a porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 1, characterized in that: Cool to room temperature at a cooling rate of 2-3°C / min.

9. A porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material prepared by the preparation method according to any one of claims 1 to 8.

10. The porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material according to claim 9, characterized in that: The mechanical strength of the porous cage-shaped coated calcium oxide / calcium hydroxide heat storage material is greater than 30 N, and the bed thermal conductivity is greater than or equal to 0.2 W / (m·K).

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