Corrosion-resistant ceramic material, method of manufacture and molten salt storage tank lining structure

Abstract

The application provides a kind of corrosion-resistant ceramic material, raw material components include: 70-80wt% particle size 1-3 μm high-purity alpha-Al2O3 powder, 15-25wt% double-stable zirconium oxide powder, 2-4wt% SiO2 sintering aid, 1-3wt% CaO sintering aid;Double-stable zirconium oxide powder is 3mol% Y2O3 and 2mol% Yb2O3 co-stable tetragonal phase ZrO2 powder, particle size is 0.5-1 μm.The application proposes a kind of molten salt storage tank lining structure, corrosion-resistant working layer, stress buffer layer, composite heat preservation layer, airtight anticorrosion layer, storage tank is provided with nitrogen protection system.Mentioned above the preparation method of molten salt storage tank lining structure.The application uses double-stable zirconium toughened alumina composite formula, fracture toughness and chlorine ion corrosion resistance are greatly improved, the expected service life under industrial conditions is greater than or equal to 20 years.The brick joint and brick body form integrated dense structure after ceramic mastic solidification, no corrosion weak point;Adopt high-temperature zirconium doped aerogel composite heat preservation structure, heat loss is reduced by more than 75%.

Description

Technical Field

[0001] This invention relates to the field of corrosion-resistant molten salt storage tank technology, and in particular to a corrosion-resistant ceramic material, a molten salt storage tank lining structure, and a preparation method thereof. Background Technology

[0002] High-temperature chloride molten salts have become the core thermal storage medium for solar thermal molten salt storage systems and third-generation nuclear reactors due to their advantages such as wide operating temperature range, high thermal density, and low cost. However, high-temperature chloride molten salts at 800-900℃ have extremely strong chloride ion corrosiveness, which places extremely stringent requirements on the corrosion resistance, high-temperature stability, and thermal shock resistance of the tank lining material.

[0003] Traditional high-temperature molten salt storage tanks are mostly lined with stainless steel or carbon steel. Due to the insufficient corrosion resistance of these metals, they corrode and penetrate rapidly in chloride molten salt environments above 800℃, resulting in a service life of only 1-2 years, which is completely unacceptable for long-term stable operation. Therefore, alumina ceramic lining structures have emerged. Compared to traditional metal materials, alumina ceramics offer improved corrosion resistance and significant advantages in high-temperature performance. However, they still have the following drawbacks in practical use:

[0004] First, its resistance to chloride ion corrosion is insufficient. While ordinary pure alumina ceramics exhibit better corrosion resistance than metallic materials, they lack specificity for chloride ion corrosion. In high-temperature chloride molten salt environments, chloride ions readily penetrate along grain boundaries and induce intergranular corrosion, resulting in a corrosion weight loss of up to 0.5 mg / cm³ after 1000 hours. 2 The ceramic tiles are prone to cracking and peeling, and the equipment has a service life of 8-10 years.

[0005] Second, preferential corrosion failure occurs at the brick joints. Existing ceramic mortars generally use pure silica sol as a binder. The SiO2 glass phase formed after high-temperature sintering has a much lower resistance to chloride ion corrosion than the alumina brick itself, making the brick joints a weak point in the entire lining structure. Molten salt easily penetrates along the brick joints, leading to overall lining failure.

[0006] Third, the thermal insulation performance is insufficient. Existing insulation layers mostly adopt a composite structure of nanoporous calcium silicate and ceramic fiber blankets. Under 900℃ conditions, the thermal conductivity is ≥0.05W / (m·K), the heat loss of the storage tank throughout the day is ≥0.8%, the energy consumption is large, and the insulation layer is thick, occupying too much floor space.

[0007] Fourth, poor thermal shock stability. The existing lining structure lacks a reasonable stress buffer design. During the heating and cooling process, the thermal stress generated by the thermal expansion and contraction of the ceramic bricks cannot be effectively released, which can easily lead to cracking and falling off of the bricks, making it unsuitable for distributed operating conditions with frequent start-stop cycles.

[0008] In summary, existing technologies still have significant limitations and are insufficient to meet the core requirements of 800-900℃ high-temperature chloride molten salt storage tanks for long service life, low loss, and high reliability. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a corrosion-resistant ceramic material, a molten salt storage tank lining structure, and a preparation method, which solves the problems of insufficient resistance to chloride ion corrosion of bricks, preferential corrosion of brick joints, poor thermal insulation performance, and weak thermal shock stability in existing technologies.

[0010] In a first aspect, according to an embodiment of the present invention, a corrosion-resistant ceramic material is provided, the raw material components of which include: 70-80wt% high-purity α-Al2O3 powder, 15-25wt% bis-stable zirconium oxide powder, 2-4wt% SiO2 sintering aid, and 1-3wt% CaO sintering aid.

[0011] The α-Al2O3 powder is a high-purity powder with a particle size of 1-3 μm;

[0012] The bistable zirconia powder is a tetragonal ZrO2 powder co-stabilized by 3 mol% Y2O3 and 2 mol% Yb2O3, with a particle size of 0.5-1 μm.

[0013] Preferably, the sintering aid is introduced in the form of an aluminosilicate sol, wherein the aluminosilicate molar ratio of aluminum to silicon is 3:2, the solid content is ≥25%, and the amount added is 5-10% of the total mass of the powder.

[0014] Preferably, the ceramic material has a room temperature flexural strength ≥450MPa, a high temperature flexural strength ≥380MPa at 1000℃, and a fracture toughness ≥6.5MPa·m. 1 / 2 Corrosion weight loss ≤ 0.05 mg / cm³ in a 900℃ chloride molten salt environment for 1000 hours. 2 .

[0015] Preferably, the room temperature thermal conductivity of the ceramic material is ≤18W / (m·K).

[0016] Secondly, the present invention proposes a molten salt storage tank lining structure, which uses the above-mentioned corrosion-resistant ceramic material, including a corrosion-resistant working layer, a stress buffer layer, a composite heat insulation layer and an airtight anti-corrosion layer arranged sequentially from the inside to the outside, and the storage tank is equipped with a nitrogen protection system.

[0017] The corrosion-resistant working layer has a thickness of 15-25mm and is formed by stacking ceramic bricks made of the corrosion-resistant ceramic material. The joints between the ceramic bricks are filled with ceramic mortar made of the corrosion-resistant ceramic material.

[0018] The stress buffer layer has a thickness of 8-12mm and is made of lightweight mullite ceramic fiber board;

[0019] The composite insulation layer has a thickness of 180-220mm, consisting of a 50-80mm thick nanoporous calcium silicate insulation board, a 50-100mm thick high-temperature aerogel composite ceramic fiber board, and a 30-50mm thick high-alumina ceramic fiber blanket from the inside out.

[0020] The airtight anti-corrosion layer is a 3-5mm thick stainless steel tank shell, and the inner side of the shell is sprayed with a 500-800μm thick alumina ceramic coating.

[0021] The nitrogen protection system is connected to the top of the molten salt storage tank to maintain a slightly positive pressure anhydrous nitrogen atmosphere of 0.01-0.03 MPa inside the tank.

[0022] Furthermore, the ceramic mortar uses aluminosilicate sol as a binder, wherein the aluminosilicate sol has an aluminosilicate molar ratio of 3:2, a solid content of ≥25%, a pH value of 2-4, and an addition amount of 8-12% of the total powder mass.

[0023] Furthermore, the high-temperature aerogel composite ceramic fiber board is a zirconium-doped silica aerogel composite high-silica ceramic fiber board.

[0024] Furthermore, the storage tank is equipped with a DCS control system with built-in molten salt temperature interlock protection, controlling the minimum molten salt temperature to be ≥420℃.

[0025] Thirdly, the present invention also proposes a method for preparing the above-mentioned molten salt storage tank lining structure, comprising the following steps:

[0026] S1. Ceramic brick preparation: Weigh the raw materials according to the formula, add anhydrous ethanol and dispersant, ball mill for 24-48 hours, spray granulate to obtain ceramic powder of 50-100μm; prepare ceramic brick green bodies by dry pressing; place the ceramic brick green bodies in an air atmosphere, keep at 1550-1650℃ for 2-4 hours for pressureless sintering, and after grinding and polishing, the dimensional tolerance is ≤±0.2mm;

[0027] S2. Preparation of ceramic mortar: Ceramic powder with the same formula as ceramic bricks is used, and aluminum silicate sol binder is added and stirred to make a paste-like ceramic mortar with a solid content of ≥70wt%.

[0028] S3. Pretreatment of the inner wall of the storage tank: Sandblasting is performed on the inner wall of the outer shell to remove rust, and a 500-800μm thick alumina ceramic coating is sprayed on. After curing, the surface roughness Ra≤6.3μm.

[0029] S4. Lining Processing: The outer shell serves as an airtight and corrosion-resistant layer. Then, a composite insulation layer, a stress buffer layer, and a corrosion-resistant working layer are sequentially constructed on the inner wall of the outer shell. The composite insulation layer is laid with staggered joints, and the gaps between the layers are filled with ceramic fiber cotton. The stress buffer layer is laid as a whole board without splicing gaps. The corrosion-resistant working layer is constructed with ceramic bricks, and the brick joints are fully filled with ceramic mortar. It is cured at room temperature for no less than 24 hours.

[0030] S5. Heating and curing: The processed storage tank is cured by step heating. The temperature is raised to 200℃ at a rate of 0.5-1℃ / min and held for 4 hours, then raised to 400℃ and held for 4 hours, then raised to 600℃ and held for 6 hours. The tank is then cooled to room temperature with the furnace to complete the curing and sintering of the ceramic mortar, so that the brick joints and the brick body form an integrated structure.

[0031] S6. Installation and commissioning of nitrogen protection system: Install a nitrogen protection system on the top of the storage tank. After commissioning, it can maintain a slightly positive pressure anhydrous nitrogen atmosphere of 0.01-0.03MPa inside the tank.

[0032] Furthermore, in step S5, dry nitrogen gas is introduced throughout the stepwise heating and curing process to prevent the putty from reacting with moisture in the air and to ensure the quality of curing and sintering.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. A bistabilized zirconia-toughened alumina composite formula is adopted. Zirconia phase transformation toughening is achieved through the co-stabilization of Y₂O₃ and Yb₂O₃, resulting in a fracture toughness improvement of over 100% compared to pure alumina ceramics. Simultaneously, densification sintering achieves a closed-porosity of ≥95%, blocking chloride ion penetration pathways; corrosion weight loss in a 900℃ chloride molten salt environment for 1000 hours is ≤0.05 mg / cm³. 2 It reduces costs by more than 10 times compared to pure alumina ceramics, and its expected service life under industrial conditions is ≥20 years, far exceeding that of existing products.

[0035] 2. Ceramic mortar is formed by using ceramic powder with the same formula as the brick body and aluminum silicate sol binder with the corresponding mullite stoichiometric ratio. After high-temperature curing, it forms a mullite phase with the same corrosion resistance as the brick body, solving the problem of insufficient corrosion resistance of pure silica sol mortar. After curing, the brick joints and the brick body form an integrated and dense structure with no weak points for corrosion, which greatly improves the overall service life of the lining structure.

[0036] 3. The high-temperature zirconium-doped aerogel composite insulation structure is adopted, with a thermal conductivity of ≤0.03W / (m·K) at 900℃. The heat loss of the storage tank throughout the day is reduced from ≥0.8% of the existing scheme to ≤0.2%, and the heat loss is reduced by more than 75%. Under the same heat loss requirements, the total thickness of the insulation layer can be reduced by 30%-40%, which greatly reduces the footprint of the storage tank and reduces space constraints.

[0037] 4. The stress buffer layer in this invention can completely absorb the thermal stress generated by the thermal expansion and contraction of ceramic bricks, and there is no risk of cracking during the heating and cooling process; at the same time, the thermal expansion coefficients of the four-layer structure are matched in sequence, and there is no risk of interface delamination or debonding; combined with the nitrogen micro positive pressure protection system and molten salt anti-condensation interlock control, it avoids the problems of molten salt hydrolysis and solidification blockage in traditional storage tanks, and can adapt to the distributed working conditions of frequent start and stop.

[0038] 5. All preparation and masonry processes in this invention use mature equipment and technology in the industry, without the need for newly developed non-standard processes. The yield of ceramic bricks is ≥98%, the masonry construction cycle is shortened by more than 30% compared with the existing solutions, and the overall operation and maintenance cost is reduced by more than 50%, which meets the conditions for large-scale industrial promotion. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the axial cross-section of the molten salt storage tank lining structure according to an embodiment of the present invention.

[0040] Figure 2 This is a flowchart illustrating the manufacturing process of the molten salt storage tank lining structure in an embodiment of the present invention.

[0041] In the above attached diagram: 1. Corrosion-resistant working layer; 2. Stress buffer layer; 3. Composite insulation layer; 4. Airtight anti-corrosion layer. Detailed Implementation

[0042] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Example 1:

[0044] This embodiment provides a 50m model adapted to a 1MW-level CO2 power generation system. 3 The specific parameters for the lining of a high-temperature chloride molten salt storage tank are as follows:

[0045] The corrosion-resistant ceramic material formula is as follows: 75wt% high-purity α-Al2O3 powder with a particle size of 1-3μm, 20wt% bis-stable zirconia powder, 3wt% SiO2 sintering aid, and 2wt% CaO sintering aid.

[0046] The bistable zirconia powder is a tetragonal ZrO2 powder co-stabilized by 3 mol% Y2O3 and 2 mol% Yb2O3, with a particle size of 0.8 μm. The sintering aid is introduced in the form of an aluminosilicate sol with an aluminum-silicon molar ratio of 3:2, a solid content of 30%, and an addition amount of 8% of the total powder mass.

[0047] like Figure 1As shown, the molten salt storage tank lining structure of this embodiment includes, from the inside out, a corrosion-resistant working layer 1, a stress buffer layer 2, a composite insulation layer 3, and an airtight anti-corrosion layer 4, and is equipped with a nitrogen protection system. Specifically, the corrosion-resistant working layer 1 is located on the innermost side of the storage tank, in close contact with the molten salt. Wherein:

[0048] The corrosion-resistant working layer 1 is 20mm thick and is formed by stacking ceramic bricks prepared from the aforementioned corrosion-resistant ceramic material. Specifically, the ceramic bricks are 200mm × 100mm × 20mm in size, with a dovetail groove structure and a 2mm high limit protrusion at the bottom. During processing, staggered joints are used, with a joint width ≤ 0.3mm. The joints between the ceramic bricks are filled with ceramic mortar prepared from the same ceramic material. The ceramic mortar uses alumina-silica sol as a binder, with an aluminum-silica molar ratio of 3:2, a solid content ≥ 25%, a pH value of 2-4, and an addition amount of 10% of the total powder mass.

[0049] The stress buffer layer 2 is 10mm thick and is made of lightweight mullite ceramic fiber board with a compressive strength ≥6MPa and a long-term service temperature ≥1200℃.

[0050] The composite insulation layer 3 is 200mm thick, consisting of a 65mm thick nanoporous calcium silicate insulation board, a 75mm thick zirconium-doped silica aerogel composite high-silica ceramic fiber board, and a 40mm thick high-alumina ceramic fiber blanket, from the inside out.

[0051] The airtight anti-corrosion layer 4 is a 4mm thick 316L stainless steel shell, and the inside of the shell is coated with a 650μm thick alumina ceramic coating.

[0052] The nitrogen protection system is connected to the top of the molten salt storage tank to maintain a slightly positive pressure of 0.02 MPa anhydrous nitrogen atmosphere inside the tank. It is equipped with a DCS control system with built-in molten salt temperature interlock protection, controlling the minimum molten salt temperature to ≥420℃.

[0053] like Figure 2 As shown, this embodiment uses the following steps to prepare the molten salt storage tank lining structure:

[0054] (1) Weigh the raw materials according to the formula, add anhydrous ethanol and dispersant, ball mill for 36 hours, spray granulate to obtain ceramic powder with 75 μm; prepare ceramic brick green body by dry pressing; place the ceramic brick green body in air atmosphere, keep at 1600℃ for 3 hours for pressureless sintering, and after grinding and polishing, the dimensional tolerance is ≤ ±0.2 mm.

[0055] (2) Use 75wt% ceramic powder with the same formula as ceramic bricks, add 25wt% aluminum silicate sol binder, and stir to make a paste-like ceramic mortar with a solid content of 75wt%.

[0056] (3) Sandblasting is performed on the inner wall of the outer shell to remove rust, and a 650μm thick alumina ceramic coating is applied. After curing, the surface roughness Ra≤6.3μm;

[0057] (4) The outer shell serves as an airtight anti-corrosion layer. Then, a composite insulation layer, a stress buffer layer, and a corrosion-resistant working layer are constructed sequentially on the inner wall of the outer shell. The composite insulation layer is laid with staggered joints, and the gaps between the layers are filled with ceramic fiber cotton. The stress buffer layer is laid as a whole board without any splicing gaps. The corrosion-resistant working layer is constructed with staggered joints of ceramic bricks with dovetail groove structure. The dovetail grooves of adjacent bricks are interlocked, and the brick joints are filled with ceramic mortar. It is cured at room temperature for 24 hours.

[0058] (5) The processed storage tank is solidified by step heating, maintaining a dry nitrogen environment, heating to 200℃ at a rate of 0.8℃ / min and holding for 4 hours, then heating to 400℃ and holding for 4 hours, then heating to 600℃ and holding for 6 hours, and then cooling to room temperature with the furnace to complete the solidification and sintering of the ceramic mortar, so that the brick joints and the brick body form an integrated structure.

[0059] (6) Install a nitrogen protection system on the top of the storage tank. After commissioning, it can maintain a 0.02MPa slightly positive pressure anhydrous nitrogen atmosphere inside the tank.

[0060] The performance test results of the molten salt storage tank lining prepared in this embodiment are as follows: flexural strength at room temperature ≥480MPa, flexural strength at 1000℃ ≥400MPa, and fracture toughness ≥6.8MPa·m. 1 / 2 Corrosion weight loss in a 900℃ high-purity chloride molten salt environment for 1000 hours is ≤0.04mg / cm³. 2 The bonding strength between the ceramic mortar and the brickwork interface after curing is ≥18MPa, and the corrosion weight loss after 1000h under the same working conditions is ≤0.08mg / cm³. 2 The heat loss of the storage tank under 900℃ conditions is ≤0.18% throughout the day, and the outer wall temperature is ≤38℃. After 100 cycles of heating and cooling, the inner lining shows no cracking, no peeling, and no leakage.

[0061] Example 2:

[0062] This embodiment provides a 500m model adapted to a 10MW-class SO2 power generation system. 3 The specific parameters for the lining of a large high-temperature chloride molten salt storage tank are as follows:

[0063] The corrosion-resistant ceramic material formula is as follows: 80wt% high-purity α-Al2O3 powder with a particle size of 3μm, 15wt% bis-stable zirconia powder, 4wt% SiO2 sintering aid, and 1wt% CaO sintering aid.

[0064] The bistable zirconia powder is a tetragonal ZrO2 powder co-stabilized by 3 mol% Y2O3 and 2 mol% Yb2O3, with a particle size of 1 μm. The sintering aid is introduced in the form of an aluminosilicate sol, wherein the aluminosilicate molar ratio is 3:2, the solid content is 35%, and the addition amount is 10% of the total mass of the powder.

[0065] like Figure 1 As shown, the molten salt storage tank lining structure of this embodiment includes, from the inside out, a corrosion-resistant working layer, a stress buffer layer, a composite insulation layer, and an airtight anti-corrosion layer, and is equipped with a nitrogen protection system. Wherein:

[0066] The corrosion-resistant working layer is 25mm thick and is formed by stacking ceramic bricks made from the aforementioned corrosion-resistant ceramic material. Specifically, the ceramic bricks are 300mm × 150mm × 25mm in size, with a dovetail groove structure and a 2mm high limit protrusion at the bottom. During processing, staggered joints are used, with a joint width ≤ 0.3mm. The joints between the ceramic bricks are filled with ceramic mortar made from the same ceramic material. The ceramic mortar uses alumina-silica sol as a binder, with an aluminum-silica molar ratio of 3:2, a solid content ≥ 25%, a pH value of 2-4, and an addition amount of 10% of the total powder mass.

[0067] The stress buffer layer is 12mm thick and is made of lightweight mullite ceramic fiberboard.

[0068] The composite insulation layer is 220mm thick, consisting of an 80mm thick nanoporous calcium silicate insulation board, a 100mm thick zirconium-doped silica aerogel composite high-silica ceramic fiber board, and a 50mm thick high-alumina ceramic fiber blanket, from the inside out.

[0069] The airtight anti-corrosion layer is a 5mm thick 316L stainless steel shell, and the inside of the shell is coated with an 800μm thick alumina ceramic coating.

[0070] In this embodiment, a 10mm thick SiC ceramic load-bearing plate is added to the bottom of the molten salt storage tank to improve its load-bearing capacity.

[0071] The nitrogen protection system is connected to the top of the molten salt storage tank to maintain a slightly positive pressure of 0.03 MPa anhydrous nitrogen atmosphere inside the tank. It is equipped with a DCS control system with built-in molten salt temperature interlock protection, controlling the minimum molten salt temperature to ≥420℃.

[0072] like Figure 2 As shown, this embodiment uses the following steps to prepare the molten salt storage tank lining structure:

[0073] (1) Weigh the raw materials according to the formula, add anhydrous ethanol and dispersant, ball mill for 48 hours, spray granulate to obtain ceramic powder with 100μm; prepare ceramic brick green body by dry pressing; place the ceramic brick green body in air atmosphere, keep at 1650℃ for 4 hours for pressureless sintering, and after grinding and polishing, the dimensional tolerance is ≤±0.2mm.

[0074] (2) Use 80wt% ceramic powder with the same formula as ceramic bricks, add 20wt% aluminum silicate sol binder, and stir to make a paste-like ceramic mortar with a solid content of 80wt%.

[0075] (3) Sandblast the inner wall of the outer shell to remove rust, and spray an 800μm thick alumina ceramic coating. After curing, the surface roughness Ra≤6.3μm;

[0076] (4) The outer shell serves as an airtight anti-corrosion layer. Then, a composite insulation layer, a stress buffer layer, and a corrosion-resistant working layer are constructed sequentially on the inner wall of the outer shell. The composite insulation layer is laid with staggered joints, and the gaps between the layers are filled with ceramic fiber cotton. The stress buffer layer is laid as a whole board without any splicing gaps. The corrosion-resistant working layer is constructed with staggered joints of ceramic bricks with dovetail groove structure. The dovetail grooves of adjacent bricks are interlocked, and the brick joints are filled with ceramic mortar. It is cured at room temperature for 24 hours.

[0077] (5) The processed storage tank is solidified by step heating, maintaining a dry nitrogen environment, heating to 200℃ at a rate of 1℃ / min and holding for 4 hours, then heating to 400℃ and holding for 4 hours, then heating to 600℃ and holding for 6 hours, and then cooling to room temperature with the furnace to complete the solidification and sintering of the ceramic mortar, so that the brick joints and the brick body form an integrated structure.

[0078] (6) Install a nitrogen protection system on the top of the storage tank. After commissioning, it can maintain a slightly positive pressure anhydrous nitrogen atmosphere of 0.03MPa inside the tank.

[0079] Example 3:

[0080] This embodiment provides a 25m model adapted to a 0.5MW-class SO2 power generation system. 3 The specific parameters for the lining of a high-temperature chloride molten salt storage tank are as follows:

[0081] The corrosion-resistant ceramic material formula is as follows: 70wt% high-purity α-Al2O3 powder with a particle size of 1μm, 25wt% bis-stable zirconia powder, 2wt% SiO2 sintering aid, and 3wt% CaO sintering aid.

[0082] The bistable zirconia powder is a tetragonal ZrO2 powder co-stabilized by 3 mol% Y2O3 and 2 mol% Yb2O3, with a particle size of 0.5 μm. The sintering aid is introduced in the form of an aluminosilicate sol with an aluminum-silicon molar ratio of 3:2, a solid content ≥25%, and an addition amount of 5% of the total powder mass.

[0083] like Figure 1 As shown, the molten salt storage tank lining structure of this embodiment includes, from the inside out, a corrosion-resistant working layer, a stress buffer layer, a composite insulation layer, and an airtight anti-corrosion layer, and is equipped with a nitrogen protection system. Wherein:

[0084] The corrosion-resistant working layer is 15mm thick and is formed by stacking ceramic bricks made from the aforementioned corrosion-resistant ceramic material. Specifically, the ceramic bricks are 150mm × 80mm × 15mm in size, with a dovetail groove structure and a 2mm high limit protrusion at the bottom. During processing, staggered joints are used, with a joint width ≤0.3mm. The joints between the ceramic bricks are filled with ceramic mortar made from the same ceramic material. The ceramic mortar uses alumina-silica sol as a binder, with an aluminum-silica molar ratio of 3:2, a solid content ≥25%, a pH value of 2-4, and an addition amount of 10% of the total powder mass.

[0085] The stress buffer layer is 8mm thick and made of lightweight mullite ceramic fiber board. It has a compressive strength of ≥6MPa and a long-term operating temperature of ≥1200℃.

[0086] The composite insulation layer is 180mm thick, consisting of a 50mm thick nanoporous calcium silicate insulation board, a 50mm thick zirconium-doped silica aerogel composite high-silica ceramic fiber board, and a 30mm thick high-alumina ceramic fiber blanket, from the inside out.

[0087] The airtight anti-corrosion layer is a 3mm thick 316L stainless steel shell, and the inside of the shell is coated with a 500μm thick alumina ceramic coating.

[0088] The nitrogen protection system is connected to the top of the molten salt storage tank to maintain a slightly positive pressure anhydrous nitrogen atmosphere of 0.01 MPa inside the tank. It is equipped with a DCS control system with built-in molten salt temperature interlock protection, controlling the minimum molten salt temperature to ≥420℃.

[0089] like Figure 2 As shown, this embodiment uses the following steps to prepare the molten salt storage tank lining structure:

[0090] (1) Weigh the raw materials according to the formula, add anhydrous ethanol and dispersant, ball mill for 24 hours, spray granulate to obtain ceramic powder with 50 μm; prepare ceramic brick green body by dry pressing; place the ceramic brick green body in air atmosphere, keep at 1550℃ for 2 hours for pressureless sintering, and after grinding and polishing, the dimensional tolerance is ≤ ±0.2 mm.

[0091] (2) Use 70wt% ceramic powder with the same formula as ceramic bricks, add 30wt% aluminum silicate sol binder, and stir to make a paste-like ceramic mortar with a solid content of 70wt%.

[0092] (3) Sandblast the inner wall of the outer shell to remove rust, and spray a 500μm thick alumina ceramic coating. After curing, the surface roughness Ra≤6.3μm;

[0093] (4) The outer shell serves as an airtight anti-corrosion layer. Then, a composite insulation layer, a stress buffer layer, and a corrosion-resistant working layer are constructed sequentially on the inner wall of the outer shell. The composite insulation layer is laid with staggered joints, and the gaps between the layers are filled with ceramic fiber cotton. The stress buffer layer is laid as a whole board without any splicing gaps. The corrosion-resistant working layer is constructed with staggered joints of ceramic bricks with dovetail groove structure. The dovetail grooves of adjacent bricks are interlocked, and the brick joints are filled with ceramic mortar. It is cured at room temperature for 24 hours.

[0094] (5) The processed storage tank is solidified by step heating, maintaining a dry nitrogen environment, heating to 200℃ at a rate of 0.5℃ / min and holding for 4 hours, then heating to 400℃ and holding for 4 hours, then heating to 600℃ and holding for 6 hours, and then cooling to room temperature with the furnace to complete the solidification and sintering of the ceramic mortar, so that the brick joints and the brick body form an integrated structure.

[0095] (6) Install a nitrogen protection system on the top of the storage tank. After commissioning, it can maintain a 0.01MPa slightly positive pressure anhydrous nitrogen atmosphere inside the tank.

[0096] Comparative Example 1:

[0097] The rest of the parts in this embodiment are the same as in embodiment 1, except that the corrosion-resistant working layer is made of 99% pure alumina ceramic brick.

[0098] Performance test results: Pure alumina ceramic bricks showed a weight loss of ≥0.6 mg / cm³ after 1000 hours of corrosion in a molten chloride environment at 900℃. 2 Intergranular corrosion cracking occurs.

[0099] Comparative Example 2:

[0100] The rest of this embodiment is the same as that in embodiment 1, except that the ceramic mortar used to seal the joints of ceramic tiles uses pure silica sol as the adhesive.

[0101] Performance test results: Ceramic mortar corrosion weight loss ≥1.3mg / cm³ after 1000h. 2 The brick joints corrode first, and molten salt penetrates along the brick joints; after 30 cycles of heating and cooling, the bricks crack and fall off, and the lining fails.

[0102] Comparative Example 3:

[0103] The rest of the components in this embodiment are the same as in Embodiment 1, except that the composite insulation layer uses a nanoporous calcium silicate board plus a high-alumina ceramic fiber blanket and has no aerogel layer.

[0104] Performance test results: Under 900℃ conditions, the thermal conductivity of the insulation layer is ≥0.055W / (m·K), and the total heat loss of the storage tank throughout the day is ≥0.9%. Compared with Example 1, the total heat loss throughout the day is significantly increased; under the same heat loss requirements, the insulation layer thickness needs to be increased by more than 40%, and the floor space required is significantly increased.

[0105] Comparative Example 4:

[0106] The rest of the parts in this embodiment are the same as in embodiment 1, except that there is no stress buffer layer and the corrosion-resistant working layer is directly laid on the composite insulation layer.

[0107] Performance test results: After 10 cycles of heating and cooling, the ceramic tiles developed thermal stress cracks, and the joints became detached and leaked, making it impossible to operate stably for a long time.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. 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 be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A corrosion-resistant ceramic material, characterized in that, The raw material composition includes: 70-80wt% high-purity α-Al2O3 powder, 15-25wt% bis-stable zirconia powder, 2-4wt% SiO2 sintering aid, and 1-3wt% CaO sintering aid; The α-Al2O3 powder is a high-purity powder with a particle size of 1-3 μm; The bistable zirconia powder is a tetragonal ZrO2 powder co-stabilized by 3 mol% Y2O3 and 2 mol% Yb2O3, with a particle size of 0.5-1 μm.

2. The corrosion-resistant ceramic material as described in claim 1, characterized in that: The sintering aid is introduced in the form of aluminum-silicon sol, wherein the aluminum-silicon molar ratio in the aluminum-silicon sol is 3:2, the solid content is ≥25%, and the addition amount is 5-10% of the total mass of the powder.

3. The corrosion-resistant ceramic material as described in claim 1, characterized in that: The ceramic material has a room temperature flexural strength ≥450MPa, a high temperature flexural strength ≥380MPa at 1000℃, and a fracture toughness ≥6.5MPa·m. 1 / 2 Corrosion weight loss ≤ 0.05 mg / cm³ in a 900℃ chloride molten salt environment for 1000 hours. 2 .

4. The corrosion-resistant ceramic material as described in claim 1, characterized in that: The room temperature thermal conductivity of the ceramic material is ≤18W / (m·K).

5. A lining structure for a molten salt storage tank, using the corrosion-resistant ceramic material as described in claims 1-4, characterized in that: The tank includes, from the inside out, a corrosion-resistant working layer, a stress buffer layer, a composite insulation layer, and an airtight anti-corrosion layer, and is equipped with a nitrogen protection system. The corrosion-resistant working layer has a thickness of 15-25mm and is formed by stacking ceramic bricks made of the corrosion-resistant ceramic material. The joints between the ceramic bricks are filled with ceramic mortar made of the corrosion-resistant ceramic material. The stress buffer layer has a thickness of 8-12mm and is made of lightweight mullite ceramic fiber board; The composite insulation layer has a thickness of 180-220mm, consisting of a 50-80mm thick nanoporous calcium silicate insulation board, a 50-100mm thick high-temperature aerogel composite ceramic fiber board, and a 30-50mm thick high-alumina ceramic fiber blanket from the inside out. The airtight anti-corrosion layer is a 3-5mm thick stainless steel tank shell, and the inner side of the shell is sprayed with a 500-800μm thick alumina ceramic coating. The nitrogen protection system is connected to the top of the molten salt storage tank to maintain a slightly positive pressure anhydrous nitrogen atmosphere of 0.01-0.03 MPa inside the tank.

6. The molten salt storage tank lining structure as described in claim 5, characterized in that: The ceramic mortar uses aluminosilicate sol as a binder. The aluminosilicate sol has an aluminum-silicon molar ratio of 3:2, a solid content of ≥25%, a pH value of 2-4, and is added at 8-12% of the total mass of the powder.

7. The lining structure of a molten salt storage tank as described in claim 5, characterized in that: The high-temperature aerogel composite ceramic fiber board is a zirconium-doped silica aerogel composite high-silica ceramic fiber board.

8. The lining structure of a molten salt storage tank as described in claim 5, characterized in that: The storage tank is equipped with a DCS control system with built-in molten salt temperature interlock protection, controlling the minimum molten salt temperature to be ≥420℃.

9. A method for preparing the molten salt storage tank lining structure as described in claims 5-8, characterized in that, Includes the following steps: S1. Ceramic brick preparation: Weigh the raw materials according to the formula, add anhydrous ethanol and dispersant, ball mill for 24-48 hours, spray granulate to obtain ceramic powder of 50-100μm; prepare ceramic brick green bodies by dry pressing; place the ceramic brick green bodies in an air atmosphere, keep at 1550-1650℃ for 2-4 hours for pressureless sintering, and after grinding and polishing, the dimensional tolerance is ≤±0.2mm; S2. Preparation of ceramic mortar: Ceramic powder with the same formula as ceramic bricks is used, and aluminum silicate sol binder is added and stirred to make a paste-like ceramic mortar with a solid content of ≥70wt%. S3. Pretreatment of the inner wall of the storage tank: Sandblasting is performed on the inner wall of the outer shell to remove rust, and a 500-800μm thick alumina ceramic coating is sprayed on. After curing, the surface roughness Ra≤6.3μm. S4. Lining Processing: The outer shell serves as an airtight and corrosion-resistant layer. Then, a composite insulation layer, a stress buffer layer, and a corrosion-resistant working layer are sequentially constructed on the inner wall of the outer shell. The composite insulation layer is laid with staggered joints, and the gaps between the layers are filled with ceramic fiber cotton. The stress buffer layer is laid as a whole board without splicing gaps. The corrosion-resistant working layer is constructed with ceramic bricks, and the brick joints are fully filled with ceramic mortar. It is cured at room temperature for no less than 24 hours. S5. Heating and curing: The processed storage tank is cured by step heating. The temperature is raised to 200℃ at a rate of 0.5-1℃ / min and held for 4 hours, then raised to 400℃ and held for 4 hours, then raised to 600℃ and held for 6 hours. The tank is then cooled to room temperature with the furnace to complete the curing and sintering of the ceramic mortar, so that the brick joints and the brick body form an integrated structure. S6. Installation and commissioning of nitrogen protection system: Install a nitrogen protection system on the top of the storage tank. After commissioning, it can maintain a slightly positive pressure anhydrous nitrogen atmosphere of 0.01-0.03MPa inside the tank.

10. The corrosion-resistant ceramic material, molten salt storage tank lining structure, and preparation method as described in claim 1, characterized in that: In step S5, dry nitrogen gas is introduced throughout the stepwise heating and curing process to prevent the putty from reacting with moisture in the air and to ensure the quality of curing and sintering.

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