Preparation method of calcium-based heat storage material based on porous matrix and application thereof

Abstract

The application discloses a preparation method of a calcium-based heat storage material based on a porous base and application of the calcium-based heat storage material. Calcium acetate is repeatedly immersed into diatomite by using a repeated immersion method, so that the calcium acetate is adsorbed in the pores of the diatomite, and high-temperature calcination is performed to decompose the calcium acetate into calcium carbonate; and acetone gas generated during the decomposition is used to punch holes to form the calcium-based heat storage material. The application can improve the agglomeration problem of the calcium carbonate calcium-based heat storage material in a multiple reaction process, and prolong the service life of the material.

Description

Technical Field

[0001] This invention belongs to the field of materials engineering technology, specifically relating to a method for preparing calcium-based thermal storage materials based on porous matrices and their applications. Background Technology

[0002] Because solar energy and other energy sources are clean and green, and have abundant availability in my country, concentrated solar thermal power generation and other new energy power generation technologies are gradually becoming key technologies for achieving dual-carbon policies and green development. However, due to the unstable and unbalanced characteristics of solar energy and other new energy sources in time and space, directly integrating them into the power grid will cause instability in the power system and affect the safety of production and work. Therefore, this characteristic has become the most significant factor limiting their development.

[0003] Thermal energy storage devices, due to their ability to transfer source and load over time, can be coupled with generating units to effectively stabilize power fluctuations and enhance the absorption capacity of renewable energy. Furthermore, compared to sensible and latent heat storage, thermochemical energy storage has attracted widespread attention due to its wide temperature range, long storage time, and low heat loss. It is also considered a third-generation thermal energy storage technology for solar thermal power units due to its high storage capacity, long storage period, and stable properties.

[0004] Calcium-based thermal storage materials, especially calcium carbonate / calcium oxide reaction systems, have become a research hotspot in recent years due to their low cost, wide availability of raw materials, good thermal storage performance, and environmental friendliness. However, in practical applications, repeated charge-discharge cycles cause sintering of calcium-based materials, leading to a decline in their thermal storage performance. Therefore, the thermal storage materials need to be replaced periodically in thermal storage systems to ensure their healthy lifespan. This problem significantly increases the operating cost and safety of the unit, and is a major factor limiting its large-scale application. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing calcium-based thermal storage materials based on a porous matrix and their applications. This invention can improve the agglomeration problem of calcium carbonate-based thermal storage materials during multiple reaction processes, thereby increasing the material's service life.

[0006] The technical solution of the present invention is: a method for preparing calcium-based thermal storage material based on a porous matrix, wherein calcium acetate is impregnated into diatomaceous earth by repeated impregnation, so that it is adsorbed into the pores of diatomaceous earth, and then calcined at high temperature to decompose into calcium carbonate; the acetone gas generated during decomposition punches through the pores to form calcium-based thermal storage material.

[0007] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, calcium acetate is impregnated into diatomaceous earth in the form of a solution.

[0008] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the concentration of the calcium acetate solution does not exceed 30 g / 100 ml.

[0009] In the aforementioned method for preparing calcium-based thermal storage materials based on porous matrices, the mass fraction of diatomaceous earth is 39% to 50% of the mass of the calcium-based thermal storage material.

[0010] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the diatomaceous earth is pretreated by calcination before calcium acetate is impregnated into it.

[0011] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the calcination pretreatment process is as follows: calcination at 600°C for 6 hours.

[0012] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the impregnation process of the repeated impregnation method is as follows: calcium acetate solution is added dropwise to diatomaceous earth until the surface of the diatomaceous earth is slightly moistened, and then dried at a constant temperature; after drying, the above operation is repeated until white crystals precipitate on the surface of the diatomaceous earth.

[0013] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the constant temperature drying condition is drying at 80°C for 6 hours.

[0014] In the aforementioned method for preparing calcium-based thermal storage materials based on porous matrices, the high-temperature calcination decomposition temperature is 450–500°C.

[0015] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the materials are calcined and decomposed at high temperature and then calcined at 800°C to burn off any unreacted organic matter on the surface and to calcine calcium carbonate to generate calcium oxide.

[0016] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the calcium acetate solution is a freshly prepared solution.

[0017] In the aforementioned method for preparing calcium-based thermal storage materials based on porous substrates, the calcium acetate solution is prepared by mixing it at a constant temperature water bath temperature of 50°C.

[0018] A calcium-based thermal storage material prepared according to the aforementioned preparation method is applied to the thermochemical thermal storage reaction of a calcium carbonate / calcium oxide reaction system. Specifically, it is used as a heat transfer medium in the high-temperature steam thermal storage tank of a concentrating solar power unit or a thermal power unit. The high-temperature carbon dioxide generated by its exothermic reaction can simultaneously serve as a heat exchange medium or a flow medium to perform work or exchange heat with the outside world, for heating or supplying power to a turbine connected to a generator to generate electricity, thereby increasing the local absorption capacity of the power system for new energy power.

[0019] The advantages of this invention are as follows: Compared with existing technologies, this invention improves the adsorption performance of diatomaceous earth (silica) through calcination at different temperatures, repeatedly impregnates it with calcium acetate as a pollution-free calcium source, and uses acetone gas generated during calcination for pore punching to prepare a silica porous matrix composite calcium-based thermal storage material. In the silica porous matrix composite calcium-based thermal storage material prepared by this method, the mass proportion of the main active material is greater than that of the framework material. The main components include 50%–61% calcium carbonate doped with 50%–39% diatomaceous earth (silica). This method utilizes the chemical stability of the inert natural framework diatomaceous earth at high temperatures to improve the localized sintering and agglomeration problem that occurs in the calcium carbonate / calcium oxide reaction system thermal storage material during repeated charge-discharge cycles, and increases the porosity of the thermal storage material. The thermal storage material prepared by this invention can be used as a thermal storage medium for reaction beds or thermal storage devices in high-temperature solar integrators and boiler waste heat recovery systems, exhibiting better reaction stability and uniformity, as well as a faster reaction rate.

[0020] This invention utilizes a repeated impregnation method to maximize the immersion of calcium acetate solution into diatomaceous earth without leakage. Under high-temperature conditions, the solution comes into contact with and adsorbs at the diatomaceous earth boundary, undergoing a chemical reaction to generate calcium carbonate and acetone gas. The acetone gas escapes and perforates the material, clearing the reaction gas pathway and achieving perforation. This preparation method is low-cost, suitable for mass production, and features simple equipment and processes, easy impurity removal, and high production efficiency. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for preparing calcium-based thermal storage materials based on a porous matrix, provided in the embodiments of the present invention.

[0022] Figure 2 This is a thermogravimetric diagram of the calcination and decomposition of calcium acetate in step S3 of the material preparation method of the present invention.

[0023] Figure 3 This is an X-ray diffraction (XRD) pattern of a calcium-based thermal storage material based on a porous matrix provided in the embodiments of the present invention.

[0024] Figure 4 This is a schematic diagram of the thermogravimetric curves of a calcium-based thermal storage material based on a porous matrix and a control, pure calcium carbonate, before and after multiple cycles, as provided in the embodiments of this invention.

[0025] Figure 5 This is a SEM image of a calcium-based thermal storage material based on a porous matrix and a control calcium carbonate before and after repeated charging and releasing of heat, provided in the implementation method of this invention.

[0026] Figure 6This is a flowchart illustrating the application of a calcium-based thermal storage material based on a porous matrix, as provided in the embodiments of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Example 1.

[0029] 1. Material preparation

[0030] The calcium-based thermal storage material based on a porous matrix provided in this embodiment is obtained by a repeated impregnation method. Figure 1 This is a flowchart of the method for preparing calcium-based thermal storage materials based on a porous matrix, as provided in the embodiments of the present invention. Figure 1 As shown, the main steps include:

[0031] Step S1: Provide calcium acetate as a calcium source material as a precursor for calcium-based thermal storage materials, and prepare it into a solution of 0.3 g / ml;

[0032] Step S2: Provide natural porous diatomaceous earth matrix and pre-treat it by calcination at 200℃, 400℃, 600℃ and 800℃ for 6 hours respectively.

[0033] Step S3: The calcium acetate solution provided in step S1 is repeatedly dried and impregnated into the porous matrix after calcination and cooling at various temperatures provided in step S2 using a dropper. Each group of calcium-based thermal storage material precursors is then placed in a muffle furnace to fully decompose and impurity them to generate the finished calcium-based thermal storage material.

[0034] Preferably, the diatomaceous earth, calcium acetate, and other chemical reagents used in preparing the porous matrix-based calcium-based thermal storage material of this invention are all of analytical grade, with high purity and very few interfering impurities. This minimizes the impact of impurities on the purity of the porous matrix-based calcium-based thermal storage material and the charge-release chemical reaction, as well as the impact of other side reactions on the wall surface on the calculation of its reaction heat and other indicators.

[0035] In step S2, 5g of each type of diatomaceous earth is calcined in a muffle furnace at 200℃, 400℃, 600℃, and 800℃ for 6 hours respectively. The pretreated and untreated materials are named A-SiO2, B-SiO2, C-SiO2, D-SiO2, and E-SiO2, respectively. High-temperature calcination causes the amorphous silica in the diatomaceous earth to shift, aiding in the growth of mesopores and enhancing its adsorption capacity for the calcium acetate solution prepared in step S1.

[0036] After repeatedly impregnating the diatomaceous earth with a calcium acetate solution to the maximum extent possible without leakage, step S3 is performed. This allows the calcium acetate crystals to come into contact with and adsorb at the diatomaceous earth boundary under high temperature conditions, resulting in a chemical reaction that generates calcium carbonate and acetone gas. The acetone gas escapes and punctures the pores, clearing the reaction gas pathways of the calcium-based thermal storage material, thus achieving pore removal. This preparation method is low-cost, suitable for mass production, and the equipment and preparation process are simple, easy to clean, and highly efficient. As a further preferred embodiment, step S3 also includes the following three sub-steps:

[0037] Step S31: Immerse the diatomaceous earth in calcium acetate solution using a dropper until the surface is slightly moistened, then place it in a constant temperature drying oven to dry. Repeat the above operation until white crystals precipitate on the surface.

[0038] Step S33: Calcium acetate is first calcined at 450°C in a muffle furnace to completely convert calcium acetate into calcium carbonate and acetone.

[0039] Step S34: Burn at 800°C in a muffle furnace to burn off any unreacted organic matter on the material surface, thus removing impurities.

[0040] 2. Material Characterization

[0041] The following experiments were used to characterize the calcium-based thermal storage material based on a porous matrix. Thermogravimetric analysis (TGA) was performed using a STA synchronous thermal analyzer from Shanghai Instrument & Electronics Co., Ltd., and X-ray diffraction (XRD) was conducted using an X-pert Power polycrystalline X-ray diffractometer manufactured by Panaco GmbH, Netherlands. Cyclic stability and other characteristics of the samples were characterized by thermogravimetric analysis (TG). 20 mg of the sample was placed in a 50 μL alumina thermal analysis crucible. The controlled program was to heat the sample from room temperature to 900 °C at a rate of 15 °C / min and hold for 10 minutes, with a nitrogen flow rate of 40 ml / min during the thermal storage process.

[0042] Figure 2 This is a thermogravimetric diagram illustrating the decomposition of calcium acetate by calcination in step S3 of the material preparation process. Figure 2 It can be seen that the material contains some water that has not been completely dried; therefore, its initial weight loss is due to the drying process of water vapor, with a weight loss of approximately 5.6%. As the temperature further increases, around 370℃, calcium acetate begins to decompose, producing calcium carbonate and acetone. Simultaneously, acetone escapes, resulting in weight loss. The reaction is complete at around 430℃, with a weight loss of approximately 33.9%. When the temperature reaches approximately 680℃, calcium carbonate begins to decompose, producing carbon dioxide that escapes, with a weight loss of approximately 33.4%. Therefore, it can be concluded that the preparation principle of the calcium precursor conforms to the process requirements.

[0043] Figure 3The figures show X-ray diffraction (XRD) analysis of calcium-based thermal storage materials based on porous matrices. As can be seen from the figures, the materials prepared using the method described in this invention are relatively pure. Figure (a) shows the composition of the reaction precursor after immersion in diatomaceous earth solution and drying; Figure (b) shows the composition of the finished calcium-based thermal storage material based on porous matrices; and Figure (c) shows the composition of the calcium-based thermal storage material generated after calcination of pure calcium acetate powder. Comparing Figures (b) and (c), it can be seen that the main component of both is calcium carbonate, and the peak heights are similar. However, Figure (b) shows the addition of a silica peak, and there are no obvious impurity peaks, indicating a result that is more satisfactory than expected.

[0044] Figure 4 This is a schematic diagram of the thermogravimetric curves (TGA) of a calcium-based thermal storage material based on a porous matrix and a control, pure calcium carbonate, before and after multiple cycles, as provided in the embodiments of this invention. The figure shows that after repeated charging and deheating, the weight loss of pure calcium carbonate decreased by 20.19%, and the material morphology in the crucible shows that it agglomerated into different hard lumps. In contrast, the calcium-based thermal storage material based on a porous matrix described in this invention showed a weight loss decrease of only 8.36%, which is only 40.45% of the decrease in pure calcium carbonate. Furthermore, its reaction temperature remained essentially unchanged, and the material morphology remained powdery. Therefore, the calcium-based thermal storage material based on a porous matrix provided by this embodiment can maintain a high degree of re-oxidation after multiple cycles, exhibiting better cycle stability.

[0045] Figure 5 The images show SEM images of a calcium-based thermal storage material based on a porous matrix provided in the embodiments of the present invention. Image (a) is an overall image of a single diatomaceous earth particle, image (b) is a partial image of image (a), and image (c) is an overall distribution image of the calcium-based thermal storage material. As can be seen from the images, the basic structure of the diatomaceous earth is preserved during the impregnation process, exhibiting a natural porous structure without adhesion, demonstrating the stability of the framework. Image (b) shows that calcium carbonate crystals are clearly attached to the surface and some pores, demonstrating the effectiveness of the thermal storage material preparation method provided in the embodiments of the present invention. Furthermore, the overall image in image (c) shows that the leakage of the calcium-based thermal storage material from the diatomaceous earth is minimal, effectively maintaining the thermal storage capacity after continuous charging and discharging.

[0046] 3. Material Application

[0047] Figure 6The flowchart provided in the implementation method of this invention describes the application of a calcium-based thermal storage material based on a porous matrix. During system operation, solar energy acts on the calcining furnace through Fresnel lenses or other means to maintain the temperature at around 750°C, calcining the calcium carbonate from the calcium carbonate storage tank or carbonation furnace, causing it to absorb heat and decompose into calcium oxide and carbon dioxide. At the same time, the opening of the valves of each branch storage tank and its parallel branch is adjusted to regulate the energy storage capacity and real-time power generation, thereby maintaining the stability of the unit's power over time.

[0048] Example 2. A calcium-based thermal storage material based on a porous matrix, wherein the calcium-based thermal storage material is a thermal storage material formed by the composite of calcium carbonate and silicon dioxide, wherein calcium carbonate is attached to the surface of diatomaceous earth as a filler.

[0049] According to this technical solution, firstly, due to the stable chemical properties of silica, it possesses strong fire resistance, high-temperature resistance, and a low coefficient of thermal expansion with good corrosion resistance. Therefore, in medium-to-high temperature environments below 1000 degrees Celsius, the silica in the porous matrix-based calcium-based thermal storage material provided in this invention will not undergo phase changes at high temperatures, nor will it react chemically with calcium acetate, calcium carbonate, calcium oxide, or carbon dioxide. While serving as an inert material framework to maintain the chemical cycle stability of the porous matrix-based calcium-based thermal storage material, it can prevent the reduction of calcium precursors and their decomposition products, as well as the main reactants (calcium carbonate / calcium oxide). Furthermore, this invention uses natural porous silica material diatomaceous earth as the filling matrix, which has abundant mesoporous and macroporous structures, thus exhibiting excellent adsorption performance.

[0050] Secondly, the applicant's experiments revealed that when using diatomaceous earth as a matrix material to fill calcium carbonate, the calcium carbonate can be stably attached to the surface of the diatomaceous earth after repeated charging and releasing of heat, and is not easy to leak or fall off.

[0051] Finally, since calcium carbonate can be adsorbed into the pores inside diatomaceous earth, it effectively isolates the aggregation of calcium carbonate particles after long-term high-temperature calcination and avoids sintering after continuous charging and discharging. As a result, the calcium-based thermal storage material based on a porous matrix provided by this invention has strong cycle stability and can maintain a high thermal storage density after multiple cycles.

[0052] In a further preferred embodiment, the porous matrix-based calcium-based thermal storage material of the present invention has a diatomaceous earth mass fraction of not less than 39% of its mass. This is mainly due to the adsorption capacity of the diatomaceous earth itself. However, if too much diatomaceous earth is used, the mass fraction of the main substance calcium carbonate will be too low, which will reduce the heat of the thermal storage reaction of the material under the same mass. In addition, if too much diatomaceous earth is used, the internal calcium carbonate will have difficulty in removing the carbon dioxide produced by the reaction in a short time, which may cause local high pressure and affect the reaction process. Therefore, excessive diatomaceous earth mass fraction can easily reduce the thermal storage density of the thermal storage material.

[0053] In a further preferred embodiment, the calcium-based thermal storage material based on a porous matrix of the present invention, in order to balance the relationship between its thermal storage density and cycle stability, sets the mass fraction of calcium carbonate as 1-A and the mass fraction of diatomaceous earth as A, with the value of A ranging from 39% to 50%.

[0054] Further preferred embodiment, as discovered by the applicant's experimental research, shows that pure calcium carbonate material exhibits significant surface agglomeration after repeated charging and deheating. In contrast, the calcium-based thermal storage material based on a porous matrix involved in this invention increases the contact area between calcium carbonate and the external environment, facilitating the escape of the reactant gas carbon dioxide. Therefore, after multiple charging and deheating reactions, the material still possesses a large reaction area, enhancing its chemical reaction kinetics and ensuring that the reaction temperature remains almost unchanged and the thermal storage capacity loss is minimal after repeated charging and deheating.

[0055] In a further preferred embodiment, to enhance the heat storage density of the material, the adsorption capacity of the natural porous matrix diatomaceous earth for calcium acetate solution, a calcium source, is of paramount importance. This invention uses high-temperature calcination to cause the amorphous silica in the diatomaceous earth to shift, thereby assisting the growth of mesopores. It was found that the diatomaceous earth with the strongest adsorption capacity was calcined at 600°C for six hours.

[0056] In another aspect, the present invention provides a method for preparing the calcium-based thermal storage material based on a porous matrix as described above, which mainly includes the following steps:

[0057] Step S1: Provide calcium acetate as a calcium source material as a precursor for calcium-based thermal storage materials, and prepare it into a solution of 0.3 g / ml;

[0058] Step S2: Provide natural porous diatomaceous earth matrix and pre-treat it by calcination at 200℃, 400℃, 600℃ and 800℃ for 6 hours respectively.

[0059] Step S3: The calcium acetate solution provided in step S1 is repeatedly dried and impregnated into the porous matrix after calcination and cooling at various temperatures provided in step S2 using a dropper. Each group of calcium-based thermal storage material precursors is then placed in a muffle furnace to fully decompose and impurity them to generate the finished calcium-based thermal storage material.

[0060] According to the technical method, a calcium acetate solution is repeatedly impregnated into diatomaceous earth to the maximum extent without leakage. Under high temperature conditions, the solution comes into contact with and adsorbs at the boundary of the diatomaceous earth, undergoing a chemical reaction to generate calcium carbonate and acetone gas. The acetone gas escapes and perforates the pores, clearing the reaction gas pathways of the calcium-based thermal storage material. This preparation method is low-cost, suitable for mass production, and the equipment and preparation process are simple, easy to clean, and highly efficient.

[0061] In a preferred embodiment of the present invention, the present invention further includes the following three sub-steps.

[0062] 1. Immerse the diatomaceous earth in calcium acetate solution using a dropper until the surface is slightly moistened, then place it in a constant temperature drying oven to dry. Repeat the above steps until white crystals precipitate on the surface.

[0063] 2: Calcium acetate is first calcined at 450℃ in a muffle furnace to completely convert calcium acetate into calcium carbonate and acetone.

[0064] 3: Burning at 800℃ in a muffle furnace burns off any unreacted organic matter on the material surface, thus removing impurities.

[0065] Another aspect of the present invention provides an application of calcium-based thermal storage material based on a porous matrix. The calcium-based thermal storage material prepared by the method of preparing calcium-based thermal storage material based on a porous matrix designed in this invention can be applied to the thermochemical thermal storage reaction of calcium carbonate / calcium oxide reaction system. It can be used as a heat transfer medium in high-temperature steam thermal storage tanks of concentrating solar power units or thermal power units. The high-temperature carbon dioxide generated by its exothermic reaction can simultaneously serve as a heat exchange medium or a flow medium to perform work or exchange heat with the outside world, for heating or supplying steam turbines to connect to generators to generate electricity, thereby increasing the local absorption capacity of new energy power in the power system.

[0066] Example 3. A method for preparing a calcium-based thermal storage material based on a porous matrix. The principle of the calcium-based thermal storage material is a calcium carbonate / calcium oxide reaction. Calcium acetate is repeatedly impregnated into diatomaceous earth porous material using a method of adsorption into the pores and then calcined at high temperature to decompose into calcium carbonate. The acetone gas generated by the reaction perforates the pores to form a porous composite thermal storage material. The mass fraction of the diatomaceous earth porous material is not higher than 50% of the porous composite thermal storage material.

[0067] The mass fraction of the porous diatomaceous earth material is A, and the mass fraction of the calcium carbonate is 1-A. The value of A mainly depends on the calcination pretreatment of the diatomaceous earth material. As shown in step S2, at 600℃, the value of A is 39%, which is the minimum value and the active material mixing ratio is the maximum.

[0068] The method for preparing calcium-based thermal storage materials based on porous matrices uses calcium acetate, which generates a large amount of organic gas, is inexpensive and pollution-free, and is easy to remove impurities, as the calcium source. It is easy to use the reaction gas to achieve pore punching, thereby increasing the porosity of the thermal storage material.

[0069] The calcium source, calcium acetate, is infiltrated into the diatomaceous earth framework in solution to form a precursor for the composite material. To prevent precipitation, the solution concentration should be controlled below 30g / 100ml.

[0070] The porous material, diatomaceous earth, is in powder form and easily clumps together after adsorbing calcium acetate solution.

[0071] The porous material diatomaceous earth was calcined in a muffle furnace at 200℃, 400℃, 600℃ and 800℃ to promote the growth of its mesopores into macropores and enhance its adsorption capacity. Among them, the diatomaceous earth calcined at 600℃ had the best adsorption effect, with an A value of 39%.

[0072] When preparing calcium acetate, a water bath with a magnetic stirrer is required. The water bath temperature is 50°C, and the mixture is stirred for 30 minutes.

[0073] The prepared calcium acetate solution should be prepared immediately before use to prevent crystal precipitation, which would affect the impregnation effect.

[0074] The prepared calcium acetate solution was used to impregnate the diatomaceous earth using a dropper. To prevent leakage of the heat storage material, the impregnation was continued until the diatomaceous earth was slightly moist.

[0075] Diatomaceous earth impregnated with calcium acetate solution needs to be dried in a constant temperature drying oven at 80°C for 6 hours.

[0076] Repeat the above impregnation and drying steps on the diatomaceous earth matrix until obvious white crystals precipitate on the surface after drying.

[0077] The calcium-based thermal storage material precursor prepared needs to be pre-calcined in a muffle furnace at 500°C for 3 hours to allow calcium acetate to fully react and generate calcium carbonate, and to allow acetone gas to completely escape to achieve perforation. After the pre-calcination, the temperature needs to be raised to 800°C and burned for 30 minutes to remove impurities from the unreacted carbon particles, and to calcine the calcium carbonate to generate calcium oxide.

[0078] A method for preparing calcium-based thermal storage materials based on a porous matrix provides a calcium-based thermal storage material that can be used as a thermal storage material in the thermochemical thermal storage reaction of a calcium carbonate / calcium oxide reaction system. It can be used as a heat transfer medium in high-temperature steam thermal storage tanks of concentrating solar power units or thermal power units. The high-temperature carbon dioxide generated by its exothermic reaction can simultaneously serve as a heat exchange medium or a flow medium to perform work or exchange heat with the outside world, for heating or supplying steam turbines to connect to generators for power generation, thereby increasing the local capacity of the power system to absorb new energy power.

[0079] The technical solution of the present invention has now been described in conjunction with the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to the specific embodiments described above. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and all such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for producing a calcium-based heat storage material based on a porous matrix, characterized in that, Calcium acetate is immersed into diatomite by repeated immersion method, and is adsorbed in the pores of diatomite, and is decomposed into calcium carbonate by high-temperature calcination; the acetone gas produced in the decomposition process is used to punch holes to form calcium-based heat storage material; the immersion process of repeated immersion method is as follows: calcium acetate solution is added dropwise into diatomite until the surface of diatomite is slightly wet, and then constant-temperature drying is performed; after drying, the above operation is repeated until white crystals are precipitated on the surface of diatomite.

2. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 1, characterized by, The concentration of calcium acetate solution is not more than 30 g / 100 ml.

3. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 1, characterized by, The mass fraction of diatomite in the calcium-based heat storage material is 39% to 50%.

4. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 1, characterized by, Before calcium acetate is immersed into diatomite, diatomite is subjected to calcination pretreatment.

5. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 4, characterized by, The process of calcination pretreatment is as follows: diatomite is calcined at 600 DEG C for 6 hours.

6. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 1, characterized by, The constant-temperature drying condition is drying at 80 DEG C for 6 hours.

7. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 1, characterized by, The high-temperature calcination decomposition temperature is 450 to 500 DEG C.

8. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 7, characterized by, After high-temperature calcination decomposition, diatomite is calcined at 800 DEG C to burn off the unreacted organic matter on the surface, and to calcine calcium carbonate into calcium oxide.

9. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 1, characterized by, The calcium acetate solution is a solution prepared on demand.

10. The method for producing a calcium-based heat storage material based on a porous substrate according to claim 1, characterized by, When the calcium acetate solution is prepared, it is stirred uniformly at a constant-temperature water bath temperature of 50 DEG C.

11. Use of a calcium-based heat storage material produced according to the production method of any one of claims 1 to 10, characterized in that It is applied to thermochemical heat storage reaction of calcium carbonate / calcium oxide reaction system.

12. Use of the calcium-based heat storage material according to claim 11, characterized in that It is specifically applied to heat transfer medium of concentrated solar power or high-temperature steam storage tank of thermal power unit, and the high-temperature carbon dioxide produced by exothermic reaction can be used as heat transfer medium or flow medium to do work or heat exchange with the outside world, and is used for heat supply or power generation by connecting steam turbine to generator, thereby increasing the local power system's ability to consume new energy power.

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