Heat-stable hot-melt lava solid-state granular material and preparation method thereof

Abstract

The application discloses a heat-stable heat storage lava solid particle and a preparation method thereof, and belongs to the technical field of energy storage materials, and comprises the following components: 68-73% of SiO2, 2.5-3.5% of SiC, 11-14% of Al2O3, 4-6% of MgO, 2-3% of Fe2O3, 2-3% of MnO2, 1.5-2.5% of TiO2, 2-3% of ZrO2, 1.5-2% of La2O3 and 1-1.5% of ZrSiO4. The heat-stable heat storage lava solid particle and the preparation method thereof have the following advantages: the raw materials are synergistic, the process is optimized, the surface is strengthened, the high-temperature stability is good, the heat storage and heat conduction performance is balanced, the mechanical and structural reliability is strong, and the corrosion resistance is good, so that the long-term stable service requirement of a high-temperature heat storage system can be met, and the operation and maintenance cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of energy storage materials technology, and in particular to a thermal storage lava solid particulate material with good thermal stability and its preparation method. Background Technology

[0002] Against the backdrop of global energy transition and the large-scale application of renewable energy, solid-state thermal storage media have become core supporting materials for scenarios such as concentrated solar power (CSP), industrial waste heat recovery, and district heating due to their high thermal density, strong safety, and no leakage risk. However, solid-state thermal storage media currently face key technical bottlenecks: first, insufficient high-temperature stability; second, an imbalance between thermal storage and thermal conductivity; and third, poor structural reliability, making it difficult to meet long-term stability requirements. Summary of the Invention

[0003] The purpose of this invention is to provide a thermal storage lava solid particle with good thermal stability and its preparation method. By leveraging raw material synergy, process optimization and surface strengthening, it achieves comprehensive advantages such as excellent high-temperature stability, good balance between thermal storage and thermal conductivity, strong mechanical and structural reliability and corrosion resistance. It can meet the long-term stable service requirements of high-temperature thermal storage systems and reduce operation and maintenance costs.

[0004] To achieve the above objectives, the present invention provides a thermally stable solid particulate material of thermally stored lava, comprising the following raw materials by weight percentage: 68%-73% SiO2, 2.5%-3.5% SiC, 11%-14% Al2O3, 4%-6% MgO, 2%-3% Fe2O3, 2%-3% MnO2, 1.5%-2.5% TiO2, 2%-3% ZrO2, 1.5%-2% La2O3, and 1%-1.5% ZrSiO4.

[0005] Furthermore, the particle size of SiO2 is 75-100 mm. Purity ≥ 98%, SiC particle size 5-8 mm Purity ≥ 99%, oxygen content ≤ 0.8%, specific surface area 1.5-2.5 ;

[0006] Al2O3 has a D50 of 5-8. of - Alumina micro powder, purity ≥99%, specific surface area 3-5 Particle size distribution Span ≤ 1.2;

[0007] MgO with a particle size of 3-5 Lightly calcined magnesium oxide powder, with MgO purity ≥95% and activity ≥65%;

[0008] Fe2O3 with a particle size of 1-2 Iron oxide red, purity ≥97%; MnO2 particle size 2-3 Electrolytic grade powder with a purity ≥98%;

[0009] TiO2 with a particle size of 1-3 Rutile titanium dioxide powder with a purity ≥99.5%;

[0010] ZrO2 is 3 mol% Y2O3 stabilized nano-zirconia powder with a particle size of 30-50 nm, tetragonal phase content ≥95%, and specific surface area of ​​20-30. ;

[0011] La2O3 with a particle size of 2-5 Lanthanum oxide powder with a purity ≥99%;

[0012] ZrSiO4 with a particle size of 3-5 Pre-synthesized zircon composite powder with a purity ≥99%, and subjected to 1600-1700... Pre-calcination stabilization treatment.

[0013] This invention also provides a method for preparing thermally stable solid particles of molten lava, comprising the following steps:

[0014] S1. Raw material pretreatment and mixing to obtain slurry, and then feeding the slurry into a centrifugal granulator for centrifugal granulation;

[0015] S2. Place the granulated wet pellet blanks into a hot air circulating drying oven to dry and remove moisture and binder to obtain heat storage pellets;

[0016] S3. The dried spherical blanks are subjected to gradient sintering to densify the spherical blanks.

[0017] S4. The sintered spherical blank is surface-strengthened and coated to obtain thermal storage lava solid particles.

[0018] Preferably, the specific operation of S1 is as follows:

[0019] S11. Add ZrO2 to deionized water, then add a composite dispersant to obtain a mixture, and then ultrasonically disperse the mixture to obtain a suspension.

[0020] S12. The ultrasonically dispersed ZrO2 suspension, SiO2, SiC, Al2O3, MgO, Fe2O3, MnO2, TiO2, La2O3, ZrSiO4, deionized water, and binder from S11 are added to a planetary ball mill and ball-milled to obtain a uniform slurry.

[0021] S13. The slurry is fed into a centrifugal granulator for molding to obtain wet pellet blanks.

[0022] Preferably, in S11, the solid-liquid ratio of ZrO2 to deionized water is 1:5, the ultrasonic dispersion power is 200-400W, the frequency is 15-30kHz, and the time is 20-40min, with stirring every 10min during the process. The composite dispersant accounts for 0.3% of the total mass of the suspension, and the composite dispersant includes sodium polyacrylate and triethanolamine, wherein sodium polyacrylate accounts for 0.2% of the total mass of the suspension, and triethanolamine accounts for 0.1% of the total mass of the suspension.

[0023] In S12, deionized water accounts for 12%-14% of the total raw material mass, and polyvinyl alcohol is the binder, accounting for 1.5%-2% of the total raw material mass, with a binder mass concentration of 8%. Agate balls are used as the grinding media in the planetary ball mill, with a ball-to-material ratio of 3:1 and a rotational speed of 250-300 rpm. The ball milling time is 70-80 minutes, and the slurry viscosity is 2000-3000. Particle size is 50-80 D50=60 ;

[0024] In S13, the centrifugal granulator speed is 900-1100. The hot air temperature is 90-100 degrees Celsius. The hot air velocity is 1.5-2. The feed rate is 50-80. The diameter of the wet pellet is 3-5mm, and the roundness is ≥0.95.

[0025] Preferably, the specific operation of S2 is as follows:

[0026] S21. The wet pellets obtained in S13 are dried in a hot air circulating drying oven in the first stage.

[0027] S22. The spherical blanks that underwent the first stage of drying in S21 are dried in the second stage to obtain heat storage balls.

[0028] Preferably, in S21, the drying temperature is 60-80°C. Keep warm for 2-3 hours, with a heating rate of 3-5. ;

[0029] In S22, the drying temperature is 120-150°C. Keep warm for 1-2 hours, with a heating rate of 3-5. .

[0030] Preferably, the specific operation of S3 is as follows:

[0031] S31. The heat storage balls obtained in S22 are placed in an air atmosphere high-temperature sintering furnace for primary sintering.

[0032] S32. Perform secondary sintering on the heat storage balls obtained by primary sintering in S31.

[0033] S33. Perform tertiary sintering on the heat storage balls obtained by secondary sintering in S32.

[0034] S34. Perform four-stage sintering on the heat storage balls obtained by the three-stage sintering in S33.

[0035] S35. Perform five-stage sintering on the heat storage balls obtained from the fourth-stage sintering in S34.

[0036] Preferably, in S31, the primary sintering temperature is increased from room temperature to 600-650°C. The heating rate is 3-5 Keep warm for 2-2.5 hours, with an internal pressure of 50 Pa.

[0037] In S32, the secondary sintering temperature is 1000-1050℃. The heating rate is 2-4 Keep warm for 1-2 hours, maintaining the CO2 concentration inside the furnace at 20%-21%;

[0038] In S33, the tertiary sintering temperature is 1200-1250℃. The heating rate is 1-2 Keep warm for 2-3 hours;

[0039] In S34, the fourth-stage sintering temperature is 1600-1650℃. The heating rate is 2-2.5. Keep warm for 3-3.5 hours;

[0040] In S35, the fifth-stage sintering temperature is 800-1000℃. The cooling rate is 1-2 Hold at the temperature for 1-1.5 hours for low-temperature annealing.

[0041] Preferably, the specific operation of S4 is as follows: the heat storage ball obtained by the five-stage sintering in S35 is completely immersed in the silica sol, then taken out and drained naturally, and after draining, the heat storage ball is placed in a hot air drying oven to dry, and the dried heat storage ball is subjected to heat preservation treatment to obtain heat storage lava solid particles.

[0042] Preferably, in step S4, the silica sol concentration is 30%, the immersion time is 12-15 minutes, with stirring every 5 minutes during this period, the natural draining time is 3-5 minutes, and the temperature in the hot air drying oven is 150-180°C. Dry for 2-3 hours, maintaining a temperature of 600-650°C. The heat preservation time is 1 hour, and after heat preservation, the surface is coated with 8-10 Solid particles of thermally stored lava in a thick, dense SiO2 layer.

[0043] Therefore, the present invention employs the above-mentioned thermally stable solid particles of thermally stored lava and its preparation method, which have the following beneficial effects:

[0044] (1) Significantly improved high-temperature stability: Relying on the skeletal support of SiC and the synergistic effect of the crystal stability of pre-fired ZrSiO4, combined with the release of internal stress by low-temperature annealing, the high-temperature volume shrinkage rate of the heat storage particles is reduced to 1.2%, 800 -25 With a thermal cycle life of over 1200 cycles, it can meet the long-term service requirements of thermal storage systems.

[0045] (2) Highly efficient balance of thermal storage and thermal conductivity: The synergistic thermal storage of multiple components (Al2O3, MgO, etc.) and the thermal conductivity pathway constructed by SiC, combined with the uniform dispersion of components achieved by the composite dispersant, result in an average specific heat capacity of 1.18 for the medium. Thermal conductivity reaches 1.85 It balances high thermal storage capacity with efficient heat transfer.

[0046] (3) Significantly enhanced mechanical and structural reliability: The gradient sintering process combined with the phase transformation toughening effect of ZrO2 increases the density of the medium to 96.5%, the compressive strength to 85MPa, the surface hardness to 620HV, and the filling breakage rate is greatly reduced, making it able to withstand mechanical impact during transportation and use.

[0047] (4) Corrosion resistance and extended service life: Surface 9 The dense SiO2 coating can effectively isolate the high-temperature oxidizing atmosphere from the heat exchange medium, prevent the internal components from oxidizing or corroding, further extend the service life of the medium, and reduce the operation and maintenance costs of the thermal storage system.

[0048] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0049] The technical solution of the present invention will be further described below through embodiments.

[0050] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0051] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0052] Example 1

[0053] This invention provides a thermally stable solid particulate material of thermally stored lava, the raw material composition of which, by weight percentage, is: 68% SiO2 (particle size 80 mm). (98.5% purity), 3% SiC (particle size 6) Purity 99.2%, oxygen content 0.6%, specific surface area 2.0. ), 12% Al2O3 (D50=6.5) of - Alumina micro powder, purity 99.3%, specific surface area 4 Particle size distribution (Span=1.1), 5% MgO (particle size 4) Lightly calcined magnesium oxide powder (MgO purity 96%, activity 68%), 2.5% Fe2O3 (particle size 1.5 mm). Iron oxide red (purity 97.5%) and 2.5% MnO2 (particle size 2.5 mm) were also present. Electrolytic grade powder, purity 98.5%, 2% TiO2 (particle size 2) Rutile titanium dioxide powder (99.6% purity), 2% ZrO2 (40nm particle size), 3mol% Y2O3 stabilized nano-zirconia powder (97% tetragonal phase content, 25% specific surface area), and 2% ZrO2 (40nm particle size). ), 1.5% La2O3 (particle size 3.5) Lanthanum oxide powder, purity 99.2%, and 1.5% ZrSiO4 (particle size 4) The pre-synthesized zircon composite powder, with a purity of 99.3%, was processed at 1650... (Pre-calcination stabilization treatment).

[0054] The above-mentioned method for preparing thermally stable solid particles of molten lava includes the following steps:

[0055] S1. Raw material pretreatment and mixing to obtain a slurry, and then feeding the slurry into a centrifugal granulator for centrifugal granulation:

[0056] S11. Add ZrO2 to deionized water, with a solid-liquid ratio of ZrO2 to deionized water of 1:5. Then add a composite dispersant to obtain a mixture. The composite dispersant accounts for 0.3% of the total mass of the suspension and includes sodium polyacrylate (0.2%) and triethanolamine (0.1%). The mixture is then ultrasonically dispersed at a power of 300W, a frequency of 22.5kHz, and a time of 30 minutes, with stirring every 10 minutes during the process, to obtain a suspension.

[0057] S12. The ultrasonically dispersed ZrO2 suspension, SiO2, SiC, Al2O3, MgO, Fe2O3, MnO2, TiO2, La2O3, ZrSiO4, deionized water (13% of the total raw material mass), and binder (polyvinyl alcohol, 1.75% of the total raw material mass, 8% by mass) from S11 are added to a planetary ball mill. Agate balls are used as the grinding media, the ball-to-material ratio is 3:1, and the rotation speed is 275 rpm. The ball milling time was 75 minutes to obtain a uniform slurry with a viscosity of 2500. The particle size is 65. D50=60 .

[0058] S13. The slurry is fed into a centrifugal granulator for molding. The centrifugal granulator speed is 1000 rpm. The hot air temperature is 95 degrees Celsius. The hot air velocity is 1.75. The feed rate is 65 The resulting wet ball blank has a diameter of 4 mm and a roundness of ≥0.95.

[0059] S2. Place the granulated wet pellets into a hot air circulating drying oven to dry and remove moisture and binder to obtain heat storage pellets:

[0060] S21. First stage of drying: Drying temperature is 70°C. Keep warm for 2.5 hours, with a heating rate of 4. .

[0061] S22, Second stage drying: Drying temperature is 135°C. Keep warm for 1.5 hours, with a heating rate of 4. .

[0062] S3. The dried spherical blanks are subjected to gradient sintering to densify them:

[0063] S31, First-stage sintering: Temperature increased from room temperature to 625°C The heating rate is 4 The furnace was kept at a constant temperature for 2.25 hours, with an internal pressure of 50 Pa.

[0064] S32, Secondary Sintering: Heating to 1025°C The heating rate is 3 The furnace was kept at a constant temperature for 1.5 hours, maintaining a CO2 concentration of 20.5% inside.

[0065] S33, Three-stage sintering: Heat to 1225℃ The heating rate is 1.5. Keep warm for 2.5 hours.

[0066] S34, Stage 4 sintering: Heat to 1625℃ The heating rate is 2.25. Keep warm for 3.25 hours.

[0067] S35, Level 5 sintering: Cooling down to 900°C The cooling rate is 1.5. The sample was kept at a low temperature for 1.25 hours and then annealed.

[0068] S4. Surface-strengthening coating of the sintered spherical blanks yields thermally stored lava solid particles:

[0069] The heat storage balls were completely immersed in silica sol (30% by mass) for 13.5 minutes, stirring every 5 minutes. Afterward, they were removed and allowed to drain naturally for 3.5 minutes. Once drained, the heat storage balls were placed in a hot air drying oven at 165°C to dry. Dry for 2.5 hours, then keep warm at 625°C. The heat preservation time is 1 hour, resulting in a surface coating of 9 Solid particles of thermally stored lava in a thick, dense SiO2 layer.

[0070] Comparative Example 1

[0071] The only difference between this comparative example and Example 1 is that SiC was not added to the raw materials, and the weight percentage of SiO2 was adjusted to 71%. All other conditions are the same.

[0072] Comparative Example 2

[0073] The only difference between this comparative example and Example 1 is that no composite dispersant was used in S11. ZrO2 was directly mixed with deionized water and then ultrasonically dispersed. All other conditions were the same.

[0074] Comparative Example 3

[0075] The only difference between this comparative example and Example 1 is that the S35 low-temperature annealing step of gradient sintering is omitted in S3, while all other conditions are the same.

[0076] Comparative Example 4

[0077] The only difference between this comparative example and Example 1 is that surface strengthening coating treatment was not performed in S4, while all other conditions are the same.

[0078] Comparative Example 5

[0079] The only difference between this comparative example and Example 1 is that the raw materials directly use particles with a diameter of 4 mm. The test used unburned ZrSiO4 powder with a purity of 99.3%, and all other conditions were the same.

[0080] The performance of the thermal storage solid spherical particles obtained in Example 1 and Comparative Examples 1-5 was investigated.

[0081] I. Thermal stability test.

[0082] The water displacement method was used to determine the sample at room temperature and 1600°C. The volume after 2 hours of heat preservation was used to calculate the volume change rate (high-temperature volume shrinkage rate). The sample was then heated at 800°C. (High temperature range) and 25 The samples were repeatedly cycled in the low-temperature zone, with each cycle held at the temperature for 1 hour. The number of cycles when the samples cracked or pulverized was recorded. The results are shown in Table 1.

[0083] Table 1. High-temperature volume shrinkage rate and thermal cycling life of the samples

[0084]

[0085] As shown in Table 1, the high-temperature volume shrinkage rate of Example 1 is much lower than that of Comparative Examples 1-3 and Comparative Example 5. The reason is:

[0086] Comparative Example 1 lacks the rigid framework formed by SiC in the SiO2 matrix because SiC was not added. SiC can suppress the viscous flow of SiO2 at high temperatures and prevent the matrix from shrinking due to particle slippage. In Example 1, the synergy between SiC and SiO2 directly reduced the volume shrinkage rate by 2.6%.

[0087] Comparative Example 5 used unburned ZrSiO4, which was heated at 1600°C. During the test, a crystal transformation from ZrSiO4 to ZrO2 and SiO2 occurs, accompanied by a volume expansion of 0.8%-1.2%. After expansion, the matrix structure becomes loose, and upon cooling, it shrinks even more. In contrast, the ZrSiO4 in Example 1, after being cooled to 1650°C... Pre-calcination has completed crystal stabilization with no additional volume change, and together with SiC, it maintains the stability of the matrix structure.

[0088] In Comparative Example 2, because no composite dispersant was used, ZrO2 easily agglomerated to form large particles, and pores were generated around the agglomerates. At high temperatures, the shrinkage of the pores led to an increase in the overall volume change rate. In Example 1, the composite dispersant made ZrO2 uniformly dispersed, filled the tiny pores, and further reduced the shrinkage rate.

[0089] Secondly, the thermal cycling life of Example 1 reaches 1200 cycles, significantly longer than Comparative Examples 1-3 and Comparative Example 5, demonstrating a substantial advantage. The reason is:

[0090] SiC has a much higher thermal conductivity than SiO2, which can quickly and evenly disperse the local thermal stress generated during thermal cycling and avoid the initiation of cracks caused by stress concentration. In contrast, there is no SiC in Comparative Example 1, and the thermal stress cannot be effectively transferred. The sample is prone to premature cracking due to excessive local stress.

[0091] Comparative Example 3 omits the low-temperature annealing step, leaving residual internal stress due to differences in heating or cooling rates after sintering. This internal stress accumulates during thermal cycling, accelerating crack propagation. Example 1's 900... Low-temperature annealing can completely release residual internal stress, which, in conjunction with the thermal stress dispersion of SiC, significantly extends cycle life.

[0092] Uniformly dispersed tetragonal ZrO2 undergoes a "tetragonal-monoclinic" phase transition under thermal shock, accompanied by a slight volume expansion, which can heal micro-cracks and prevent crack propagation. In contrast, due to ZrO2 agglomeration, Comparative Example 2 cannot exert the phase transition toughening effect, and its cycle life is only 780 cycles.

[0093] II. Thermal storage performance test.

[0094] Differential scanning calorimetry (DSC) was used in the range of 25-1000. Within a range of 10 The heating rate was tested, the average specific heat capacity was calculated, and the thermal conductivity of the sample was tested at room temperature using the hot wire method. The results are shown in Table 2.

[0095] Table 2. Average specific heat capacity and thermal conductivity of the samples

[0096]

[0097] As shown in Table 2, the average specific heat capacity of Example 1 is higher than that of Comparative Examples 1, 2, and 5, indicating that it can store more heat per unit mass. The reason is:

[0098] Al2O3 and MgO in the matrix serve as the main heat storage components, providing the basic heat storage capacity;

[0099] Fe2O3 and MnO2, as auxiliary heat storage components, can supplement heat storage capacity through lattice vibrations;

[0100] Uniformly dispersed ZrO2 can further enhance its thermal storage capacity through latent heat of phase change; in Comparative Example 2, due to ZrO2 agglomeration, the latent heat of phase change cannot be effectively utilized, resulting in a 0.1% decrease in specific heat capacity. Comparative Example 1, without SiC support, had a slightly higher matrix porosity, resulting in a lower density of the thermal storage components and a 0.06% decrease in specific heat capacity. .

[0101] Secondly, the thermal conductivity of Example 1 is significantly higher than that of Comparative Examples 1, 2, and 5, enabling rapid heat storage and release. The reason is:

[0102] SiC, as a component with high thermal conductivity, is uniformly dispersed in the matrix to form "thermal conduction pathways," directly improving the overall thermal conductivity; in contrast, Comparative Example 1, which lacks SiC, has a thermal conductivity of only 1.42. It was 23.2% lower than in Example 1;

[0103] Example 1 achieved a density of 96.5% through gradient sintering in synergy with raw materials, reducing the obstruction of heat transfer by pores; while Comparative Example 5, due to the lack of pre-sintering of ZrSiO4, produced micropores, and Comparative Example 2, due to the agglomeration of ZrO2, produced pores, both of which led to a decrease in thermal conductivity.

[0104] III. Mechanical property testing.

[0105] A spherical sample with a diameter of 4 mm was subjected to axial compression using a universal testing machine. Ten samples were tested in each group, and the average value was taken. The Vickers hardness (HV) of the sample surface was tested using a microhardness tester with a test load of 500 g and a holding pressure of 10 s. The bulk density and theoretical density of the sample were tested using the Archimedes displacement method, and the compaction density was calculated. The results are shown in Table 3.

[0106] Table 3. Compressive strength, surface hardness, and density of the samples

[0107]

[0108] As shown in Table 3, the compressive strength of Example 1 is significantly higher than that of Comparative Examples 1, 3, 4, and 5, demonstrating a clear advantage. The reason is:

[0109] As rigid particles, SiC can withstand part of the compressive load and prevent the matrix particles from slipping. In contrast, without SiC, the matrix in Comparative Example 1 is prone to particle misalignment during compression, and its compressive strength is only 62 MPa.

[0110] In Comparative Example 5, the un-pre-fired ZrSiO4 underwent a crystal transformation during sintering, resulting in microcracks that disrupted the structural continuity and a compressive strength of only 78 MPa. In contrast, the pre-fired ZrSiO4 in Example 1 was free of cracks and formed a rigid support network with SiC, thereby improving the compressive strength.

[0111] Furthermore, uniformly dispersed ZrO2 can suppress the propagation of cracks during compression, while in Comparative Example 2, due to ZrO2 agglomeration, the pores around the agglomerates become stress concentration points, making them prone to cracking, and the compressive strength is only 70 MPa.

[0112] Secondly, the surface hardness of Example 1 is 620 HV, which is higher than that of Comparative Examples 1, 2, and 5, effectively resisting surface scratches during filling and use. The reason is:

[0113] Example 1 has the highest density, fewer surface pores, and higher hardness; Comparative Example 5 has a density of only 93.5%, more surface micropores, and the lowest hardness.

[0114] The uniform distribution of SiC and ZrO2 on the surface layer can significantly improve the surface hardness; Comparative Example 1 has no SiC and its surface hardness is only 550 HV, which is 11.3% lower than that of Example 1.

[0115] Finally, the density of Example 1 reached 96.5%, which is much higher than that of Comparative Examples 1 and 5, and slightly higher than that of Comparative Example 2, which is the core guarantee of its mechanical properties and thermal stability. The reason is:

[0116] The composite dispersant ensures uniform dispersion of ZrO2 and fills the micropores;

[0117] SiC and pre-calcined ZrSiO4 form a rigid framework to prevent structural collapse during sintering;

[0118] Gradient sintering ensures that the particles are fully sintered without excessive shrinkage or cracking; any missing raw material or process will lead to a decrease in density, which in turn affects the mechanical properties.

[0119] In summary, whether it is thermal stability against high temperature deformation and thermal shock, thermal storage performance with high heat storage and high thermal conductivity, or mechanical properties with high compressive strength and high hardness, Example 1 is significantly superior to the comparative examples, and fully meets the long-term service requirements of high temperature thermal storage scenarios.

[0120] Therefore, this invention adopts the above-mentioned thermal storage lava solid particles with good thermal stability and its preparation method. With the help of raw material synergy, process optimization and surface strengthening, it achieves comprehensive advantages such as excellent high temperature stability, good balance of thermal storage and thermal conductivity, strong mechanical and structural reliability and corrosion resistance. It can meet the long-term stable service requirements of high temperature thermal storage systems and reduce operation and maintenance costs.

[0121] 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 them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A type of thermally stable solid lava particle, characterized in that: By weight percentage, it includes the following raw materials: 68% SiO2, 3% SiC, 12% Al2O3, 5% MgO, 2.5% Fe2O3, 2.5% MnO2, 2% TiO2, 2% ZrO2, 1.5% La2O3, and 1.5% ZrSiO4; The above-described method for preparing thermally stable solid particles of molten lava includes the following steps: S1. Raw material pretreatment and mixing to obtain slurry, and then feeding the slurry into a centrifugal granulator for centrifugal granulation; S2. Place the granulated wet pellet blanks into a hot air circulating drying oven to dry and remove moisture and binder to obtain heat storage pellets; S3. The dried spherical blanks are subjected to gradient sintering to densify the spherical blanks. The specific operation of S3 is as follows: S31. The heat storage balls obtained in S22 are placed in an air atmosphere high-temperature sintering furnace for primary sintering. S32. Perform secondary sintering on the heat storage balls obtained by primary sintering in S31. S33. Perform tertiary sintering on the heat storage balls obtained by secondary sintering in S32. S34. Perform four-stage sintering on the heat storage balls obtained by the three-stage sintering in S33. S35. Perform five-stage sintering on the heat storage balls obtained by the fourth-stage sintering in S34. In S31, the primary sintering temperature is increased from room temperature to 600-650°C. The heating rate is 3-5 Keep warm for 2-2.5 hours, with an internal pressure of 50 Pa. In S32, the secondary sintering temperature is 1000-1050℃. The heating rate is 2-4 Keep warm for 1-2 hours, maintaining the CO2 concentration inside the furnace at 20%-21%; In S33, the tertiary sintering temperature is 1200-1250℃. The heating rate is 1-2 Keep warm for 2-3 hours; In S34, the fourth-stage sintering temperature is 1600-1650℃. The heating rate is 2-2.

5. Keep warm for 3-3.5 hours; In S35, the fifth-stage sintering temperature is 800-1000℃. The cooling rate is 1-2 Hold at the temperature for 1-1.5 hours for low-temperature annealing; S4. The sintered spherical blank is surface-strengthened and coated to obtain thermal storage lava solid particles; The specific operation of S4 is as follows: the heat storage ball obtained by the five-stage sintering in S35 is completely immersed in the silica sol, then taken out and drained naturally. After draining, the heat storage ball is placed in a hot air drying oven to dry. The dried heat storage ball is then subjected to heat preservation treatment to obtain solid particles of heat storage lava.

2. The thermally stable solid particulate matter of thermally stored lava according to claim 1, characterized in that: The specific operation of S1 is as follows: S11. Add ZrO2 to deionized water, then add a composite dispersant to obtain a mixture, and then ultrasonically disperse the mixture to obtain a suspension. S12. The ultrasonically dispersed ZrO2 suspension, SiO2, SiC, Al2O3, MgO, Fe2O3, MnO2, TiO2, La2O3, ZrSiO4, deionized water, and binder from S11 are added to a planetary ball mill and ball-milled to obtain a uniform slurry. S13. The slurry is fed into a centrifugal granulator for molding to obtain wet pellet blanks.

3. The thermally stable solid particulate matter of thermally stored lava according to claim 2, characterized in that: In S11, the solid-liquid ratio of ZrO2 to deionized water is 1:

5. The ultrasonic dispersion power is 200-400W, the frequency is 15-30kHz, and the time is 20-40min, with stirring every 10min. The composite dispersant accounts for 0.3% of the total mass of the suspension. The composite dispersant includes sodium polyacrylate and triethanolamine, where sodium polyacrylate accounts for 0.2% of the total mass of the suspension and triethanolamine accounts for 0.1% of the total mass of the suspension. In S12, deionized water accounts for 12%-14% of the total raw material mass, and polyvinyl alcohol is the binder, accounting for 1.5%-2% of the total raw material mass, with a binder mass concentration of 8%. Agate balls are used as the grinding media in the planetary ball mill, with a ball-to-material ratio of 3:1 and a rotational speed of 250-300 rpm. The ball milling time is 70-80 minutes, and the slurry viscosity is 2000-3000. Particle size is 50-80 D50=60 ; In S13, the centrifugal granulator speed is 900-1100. The hot air temperature is 90-100 degrees Celsius. The hot air velocity is 1.5-2. The feed rate is 50-80. The diameter of the wet pellet is 3-5mm, and the roundness is ≥0.

95.

4. The thermally stable solid particulate matter of thermally stored lava according to claim 1, characterized in that: The specific operation of S2 is as follows: S21. The wet pellets obtained in S13 are dried in a hot air circulating drying oven in the first stage. S22. The spherical blanks that underwent the first stage of drying in S21 are dried in the second stage to obtain heat storage balls.

5. The thermally stable solid particulate matter of thermally stored lava according to claim 4, characterized in that: In S21, the drying temperature is 60-80°C. Keep warm for 2-3 hours, with a heating rate of 3-5. ; In S22, the drying temperature is 120-150°C. Keep warm for 1-2 hours, with a heating rate of 3-5. .

6. The thermally stable solid particulate matter of thermally stored lava according to claim 1, characterized in that: In S4, the silica sol concentration is 30%, the immersion time is 12-15 minutes, with stirring every 5 minutes during this period, and the natural draining time is 3-5 minutes. The temperature in the hot air drying oven is 150-180°C. Dry for 2-3 hours, maintaining a temperature of 600-650°C. The heat preservation time is 1 hour, and after heat preservation, the surface is coated with 8-10 Solid particles of thermally stored lava in a thick, dense SiO2 layer.

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