A forsterite-based solar heat storage ceramic and its preparation method and application

Abstract

The present invention discloses a forsterite-based solar thermal storage ceramic and its preparation method and application, comprising components in parts by mass as follows: 55-65 parts of fused magnesia, 35-45 parts of quartz sand, 4-8 parts of organic binder, 1-5 parts of compound densifier; the compound densifier is a mixture of TiO2, Sm2O3 and Y2O3, with high density, good flexural strength and high heat storage density.

Description

Technical Field

[0001] The present invention relates to the technical field of new solar energy materials, and particularly relates to a forsterite-based solar heat storage ceramic, a preparation method thereof, and an application thereof. Background Art

[0002] Solar thermal power generation is a new type of solar thermal utilization technology different from solar photovoltaic power generation. Its principle is to reflect and concentrate a large amount of sunlight on the absorption tower during the day, generate a large amount of heat, produce steam after heat exchange with water, and drive a steam turbine to generate electricity. During operation, part of the heat needs to be stored for continuous and stable power generation at night and on cloudy and rainy days. Therefore, the heat storage device is an essential part of solar thermal power generation.

[0003] Ceramics can become one of the more ideal high-temperature heat storage materials due to their good high-temperature resistance and high heat storage density. Forsterite-based materials have the advantages of high melting point, good high-temperature stability, and good chemical stability, and can be used to prepare ceramic refractory materials. However, forsterite-based materials are usually prepared using corundum and mullite as raw materials, which not only have high costs, but also the ceramic green body is prone to cracking and deformation during the sintering process, and the ceramic density is low. When forsterite-based ceramic materials are applied to solar thermal power generation, problems such as low heat storage density and poor mechanical properties occur.

[0004] Therefore, there is a need to provide a forsterite-based ceramic material with high density, good flexural strength, and high heat storage density. Summary of the Invention

[0005] In view of this, the present application provides a forsterite-based solar heat storage ceramic, a preparation method thereof, and an application thereof, which have high density, good flexural strength, and high heat storage density.

[0006] To achieve the above technical objectives, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a forsterite-based solar heat storage ceramic, including components in the following parts by mass: 55-65 parts of fused magnesia, 35-45 parts of quartz sand, 4-8 parts of organic binder, 1-5 parts of compound densifier; the compound densifier is a mixture of TiO2, Sm2O3, and Y2O3.

[0008] Preferably, the fused magnesia includes components in the following parts by mass: 85-95 parts of MgO, 1-5 parts of SiO2; 0.5-2 parts of Al2O3, 1-2 parts of Fe2O3, 1-3 parts of CaO.

[0009] Preferably, the quartz sand includes components in the following parts by mass: 95-99 parts of SiO2, 0.5-2 parts of Al2O3, 1-2 parts of Fe2O3.

[0010] Preferably, in the compound densifier, the mass ratio of TiO2, Sm2O3 and Y2O3 is 2-3:7:6.

[0011] In a second aspect, the present application provides a method for preparing a forsterite-based solar thermal storage ceramic, comprising the following steps:

[0012] S1. Mix and ball-mill fused magnesia, quartz sand and compound densifier by mass parts to obtain a mixed material;

[0013] S2. Add an organic binder to the mixed material, and then perform granulation, aging and pressing molding in sequence to obtain a green body of the forsterite-based solar thermal storage ceramic;

[0014] S3. After drying the green body of the forsterite-based solar thermal storage ceramic, sinter it at 1400-1700 °C to obtain the forsterite-based solar thermal storage ceramic.

[0015] Preferably, in step S2, the pressure for pressing molding is 30-50 KN.

[0016] Preferably, in step S2, the aging temperature is 25-30 °C and the aging time is 24-48 h.

[0017] Preferably, in step S3, the heating rate for sintering is 3-8 °C / min and the holding time for sintering is 1-2 h.

[0018] Preferably, in step S3, the drying temperature is 80-90 °C and the drying time is 24-36 h.

[0019] In a third aspect, the present application provides an application of a forsterite-based solar thermal storage ceramic in solar thermal power generation.

[0020] The beneficial effects of the present application are as follows:

[0021] The forsterite-based solar thermal storage ceramic of the present application uses fused magnesia and quartz sand as raw materials, supplemented with a compound densifier, to obtain a low-cost forsterite-based solar thermal storage ceramic; the heat storage density of the forsterite-based solar thermal storage ceramic is as high as 1200 kJ / kg (room temperature to 1000 °C), the working temperature can be as high as above 1400 °C, the water absorption rate is as low as 0.5%, the bulk density is as high as 2.93 cm -3 , the flexural strength is as high as 50.13 MPa, and there is no cracking after 30 thermal shock cycles (1100 °C to room temperature). Compared with pure forsterite, each performance is improved by nearly twice. The compound densifier TiO2, Sm2O3 and Y2O3 in this scheme synergistically improve the heat storage density, flexural strength, density and working temperature of the forsterite-based heat storage ceramic, and is more suitable for solar thermal power generation. Description of the Drawings

[0022] Figure 1 SEM image of TiO2, Sm2O3 and Y2O3 as densifiers. Detailed implementation manners

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] This application provides a forsterite-based solar thermal storage ceramic, which comprises components in the following parts by mass: 55-65 parts of fused magnesia, 35-45 parts of quartz sand, 4-8 parts of organic binder, 1-5 parts of compound densifier; the compound densifier is a mixture of TiO2, Sm2O3 and Y2O3.

[0025] In the compound densifier of this solution, Ti 4+ reacts with periclase to form magnesium titanate, eliminating periclase and improving the content and properties of forsterite. Sm2O3 and Y2O3 form a liquid phase at high temperature, providing a good environment for grain growth and densifying forsterite. The three compound densifiers improve the density and flexural strength of forsterite.

[0026] The fused magnesia comprises components in the following parts by mass: 85-95 parts of MgO, 1-5 parts of SiO2, 0.5-2 parts of Al2O3, 1-2 parts of Fe2O3, 1-3 parts of CaO.

[0027] The quartz sand comprises components in the following parts by mass: 95-99 parts of SiO2, 0.5-2 parts of Al2O3, 1-2 parts of Fe2O3. Meeting the mass fraction limits, the quartz sand of this application includes but is not limited to quartz sand from Yingde, Guangdong.

[0028] In the compound densifier, the mass ratio of TiO2, Sm2O3 and Y2O3 is 2-3:7:6. If any one of TiO2, Sm2O3 and Y2O3 is excessive, the water absorption rate and porosity increase, and the density decreases, among which the influence of Sm2O3 is the most significant.

[0029] This application provides a preparation method for a forsterite-based solar thermal storage ceramic, which comprises the following steps:

[0030] S1. Mix and ball-mill 55-65 parts of fused magnesia, 35-45 parts of quartz sand, and 1-5 parts of compound densifier by mass to obtain a mixture; this step pre-treats each raw material, and the particle size of the mixture obtained after ball-milling is 200-250 mesh; the compound densifier is a mixture of TiO2, Sm2O3 and Y2O3;

[0031] S2. Add 4 - 8 parts of organic binder to the mixture, then granulate, age, and press - mold in sequence to obtain a green body of magnesium - olivine - based solar heat - storage ceramics; the organic binder includes but is not limited to PVA; the specific steps of aging are to seal and store the granulated material in a container and age it at 25 - 30 °C for 24 - 48 h.

[0032] S3. After drying the green body of magnesium - olivine - based solar heat - storage ceramics, sinter it at 1400 - 1700 °C to obtain magnesium - olivine - based solar heat - storage ceramics; if the sintering temperature is lower than 1400 °C, the content of magnesium olivine will decrease significantly, which is not conducive to the synthesis of magnesium olivine. If the sintering temperature is higher than 1700 °C, the energy consumption increases, resulting in an increase in cost.

[0033] In step S2, the pressure for press - molding is 30 - 50 KN.

[0034] In step S3, the heating rate for sintering is 3 - 8 °C / min, and finally, keep it at 1400 - 1700 °C for heat preservation for 1 - 2 h.

[0035] In step S3, the drying temperature is 80 - 90 °C, and the drying time is 24 - 36 h.

[0036] This application provides an application of magnesium - olivine - based solar heat - storage ceramics in solar thermal power generation.

[0037] The following further illustrates this solution through specific examples.

[0038] Example 1

[0039] A preparation method of magnesium - olivine - based solar heat - storage ceramics includes the following steps:

[0040] S1. Raw material treatment: Mix 55 g of fused magnesia, 45 g of quartz sand, and 5 g of compound densifier by ball - milling to 250 mesh to obtain a mixture; the compound densifier is a mixture of TiO2, Sm2O3, and Y2O3 with a mass ratio of 3:7:6;

[0041] Among them, the fused magnesia includes the following components in mass parts: 95 parts of MgO, 1 part of SiO2; 0.5 part of Al2O3, 1 part of Fe2O3, 1 part of CaO; the quartz sand includes the following components in mass parts: 95 parts of SiO2, 2 parts of Al2O3, 1 part of Fe2O3;

[0042] S2. Granulation, aging, and molding: Add 8 g of organic binder PVA to the mixture, then granulate in sequence. After granulation, seal and store the material in a container, age it at 30 °C for 48 h, and then introduce it into a mold for press - molding to obtain a green body of magnesium - olivine - based solar heat - storage ceramics;

[0043] S3. Drying and firing: The green body of the forsterite-based solar heat storage ceramic is placed in a constant-temperature drying oven and dried at 80 °C for 24 h, then placed in a high-temperature electric furnace and fired at 1700 °C with a heating rate of 3 °C / min, and held for 2 h to obtain the forsterite-based solar heat storage ceramic. Its SEM image is shown in Figure 1 .

[0044] Example 2

[0045] A preparation method of a forsterite-based solar heat storage ceramic, comprising the following steps:

[0046] S1. Raw material treatment: 65 g of fused magnesia, 35 g of quartz sand, and 1 g of compound densifier are mixed and ball-milled to 250 mesh to obtain a mixture; the compound densifier is a mixture of TiO2, Sm2O3, and Y2O3 with a mass ratio of 3:7:6;

[0047] Among them, the fused magnesia includes the following components in mass parts: 85 parts of MgO, 1 part of SiO2; 0.5 part of Al2O3, 1 part of Fe2O3, 1 part of CaO; the quartz sand includes the following components in mass parts: 95 parts of SiO2, 0.5 part of Al2O3, 1 part of Fe2O3;

[0048] S2. Granulation, aging, and forming: 4 g of organic binder PVA is added to the mixture, and then granulation is carried out in sequence. The granulated material is sealed and stored in a container, aged at 25 °C for 24 h, and then introduced into a mold and pressed into shape to obtain a green body of the forsterite-based solar heat storage ceramic;

[0049] S3. Drying and firing: The green body of the forsterite-based solar heat storage ceramic is placed in a constant-temperature drying oven and dried at 80 °C for 36 h, then placed in a high-temperature electric furnace and fired at 1400 °C with a heating rate of 8 °C / min, and held for 1 h to obtain the forsterite-based solar heat storage ceramic.

[0050] Example 3

[0051] A preparation method of a forsterite-based solar heat storage ceramic, other contents are the same as those in Example 1, the difference is that the compound densifier is a mixture of TiO2, Sm2O3, and Y2O3 with a mass ratio of 5:9:8.

[0052] Comparative Example 1

[0053] A preparation method of a forsterite-based solar heat storage ceramic, other contents are the same as those in Example 1, the difference is that Y2O3 is not included in the compound densifier, and the dosage of the compound densifier components is the same as that in Example 1.

[0054] Comparative Example 2

[0055] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that TiO2 is not included in the compound densifier, and the dosages of the components of the compound densifier are the same as those in Example 1.

[0056] Comparative Example 3

[0057] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that Sm2O3 is not included in the compound densifier, and the dosages of the components of the compound densifier are the same as those in Example 1.

[0058] Comparative Example 4

[0059] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that the compound densifier only includes Y2O3, and the dosages of the components of the compound densifier are the same as those in Example 1.

[0060] Comparative Example 5

[0061] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that the compound densifier only includes TiO2, and the dosages of the components of the compound densifier are the same as those in Example 1.

[0062] Comparative Example 6

[0063] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that the compound densifier only includes Sm2O3, and the dosages of the components of the compound densifier are the same as those in Example 1.

[0064] Comparative Example 7

[0065] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that the compound densifier is a mixture of TiO2, Sm2O3 and Y2O3 with a mass ratio of 10:7:6.

[0066] Comparative Example 8

[0067] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that the compound densifier is a mixture of TiO2, Sm2O3 and Y2O3 with a mass ratio of 3:7:10.

[0068] Comparative Example 9

[0069] A preparation method of a forsterite-based solar thermal storage ceramic, the other contents are the same as those in Example 1, the difference is that the compound densifier is a mixture of TiO2, Sm2O3 and Y2O3 with a mass ratio of 3:10:6.

[0070] Comparative Example 10

[0071] A preparation method of a forsterite-based solar heat storage ceramic, with other contents being the same as those in Example 1, except that it does not include a compound densifier.

[0072] Evaluation test

[0073] The performance of the forsterite-based solar heat storage ceramics obtained in Examples 1-3 and Comparative Examples 1-10 was evaluated, and the results are shown in Table 1, where:

[0074] Flexural strength: An electronic universal testing machine (RGM-4100 of Shenzhen Rigel) was used to measure the flexural strength of the samples.

[0075] Specific heat capacity: A microcalorimeter (C80 microcalorimeter of Setaram Company, France) was used to measure the specific heat of the samples, and the heat storage density was obtained correspondingly.

[0076] Water absorption rate and bulk density: According to Archimedes' principle, the static weighing method was used to test the water absorption rate and bulk density of the samples. The larger the bulk density, the higher the density.

[0077] Table 1 Test results

[0078]

[0079] Comparing Example 1 with Comparative Example 10, it can be seen that the compound densifier can nearly double the performance of pure forsterite, and the heat storage density is also greatly improved. From Comparative Examples 1-3, it can be seen that the performance changes greatly when one of the three additives is missing, and none of them can be missing. Comparative Examples 4-6 and Comparative Examples 7-9 show that the water absorption rate of the single additive is increased compared with the composite additive, and the flexural strength is reduced. When the single additive is in excess, the performance is further reduced, and the flexural strength is the most obvious.

[0080] Taking Comparative Example 10 as the blank control, the change degree of the flexural strength and heat storage density of Example 1 is much greater than the sum of the change degrees of Comparative Example 1 and Comparative Example 4; taking Comparative Example 10 as the blank control, the change degree of the flexural strength and heat storage density of Example 1 is much greater than the sum of the change degrees of Comparative Example 2 and Comparative Example 5; taking Comparative Example 10 as the blank control, the change degree of the flexural strength and heat storage density of Example 1 is much greater than the sum of the change degrees of Comparative Example 3 and Comparative Example 6; it shows that TiO2, Sm2O3 and Y2O3 can synergistically improve the flexural strength and heat storage density of the product.

[0081] In Comparative Example 5, the addition of a single TiO2 caused enstatite, cristobalite and periclase in the sample to disappear, and magnesium titanate appeared, resulting in an increase in the crystal grains of forsterite, clear grain boundaries and a decrease in pores. See Figure 1 . When a single Sm2O3 was added, there was a small amount of periclase in the sample and a small amount of Sm appeared4.66 O(SiO4)3, the crystal grains gradually increase, making the structure relatively dense. When adding a single Y2O3, there are a small amount of periclase in the sample, generating a small amount of Mg5Y6Si5O2, and the structure is relatively compact. The composite additives TiO2, Sm2O3 and Y2O3 make the periclase disappear in the sample, the content of forsterite increases, Sm(TiO3) appears, and an extremely small amount of Ti 4+ reacts with Mg 2+ to make the periclase disappear. The presence of the additives Sm2O3 and Y2O3 makes the sample generate a liquid phase during the firing process, providing a good environment for the crystal grain development, making the structure between the crystal grains more compact, which is beneficial to the densification of the structure. Therefore, the composite additive has a high density.

[0082] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A forsterite-based solar thermal storage ceramic, characterized in that, It comprises components with the following mass parts: 55 - 65 parts of fused magnesia, 35 - 45 parts of quartz sand, 4 - 8 parts of organic binder, 1 - 5 parts of compound densifier; the compound densifier is a mixture of TiO2, Sm2O3 and Y2O3; the fused magnesia comprises components with the following mass parts: 85 - 95 parts of MgO, 1 - 5 parts of SiO2, 0.5 - 2 parts of Al2O3, 1 - 2 parts of Fe2O3, 1 - 3 parts of CaO; in the compound densifier, the mass ratio of TiO2, Sm2O3 and Y2O3 is 2 - 3:7:

6.

2. The forsterite-based solar heat storage ceramic according to claim 1, wherein, The quartz sand comprises components with the following mass parts: 95 - 99 parts of SiO2, 0.5 - 2 parts of Al2O3, 1 - 2 parts of Fe2O3.

3. A preparation method of the forsterite-based solar thermal storage ceramic according to any one of claims 1-2, characterized in that, It includes the following steps: S1. Mix and ball-mill the fused magnesia, quartz sand and compound densifier by mass parts to obtain a mixed material. S2. Add the organic binder to the mixed material, then granulate, age and press-mold in sequence to obtain a green body of magnesium olivine-based solar heat storage ceramics. S3. After drying the green body of the magnesium olivine-based solar heat storage ceramics, sinter it at 1400 - 1700 °C to obtain the magnesium olivine-based solar heat storage ceramics.

4. The preparation method according to claim 3, wherein In step S2, the pressure for press-molding is 30 - 50 KN.

5. The preparation method according to claim 3, characterized in that, In step S2, the aging temperature is 25 - 30 °C and the aging time is 24 - 48 h.

6. The preparation method according to claim 3, characterized in that, In step S3, the heating rate for sintering is 3 - 8 °C / min and the holding time for sintering is 1 - 2 h.

7. The preparation method according to claim 3, characterized in that, In step S3, the drying temperature is 80 - 90 °C and the drying time is 24 - 36 h.

8. Application of the magnesium olivine-based solar heat storage ceramics according to any one of claims 1 - 2 in solar thermal power generation.

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