Filter tube mold, ceramic filter tube and preparation method thereof, dust removal and denitration integrated ceramic filter tube

Abstract

The application provides a filter tube mold, a ceramic filter tube and a preparation method thereof, and a dust removal and denitration integrated ceramic filter tube. The filter tube mold comprises an inner layer pipe and an outer layer pipe which are sleeved, the inner layer pipe is a hollow pipe, the outer pipe wall of the outer layer pipe is provided with an outward protrusion, and an annular space is formed between the inner layer pipe and the outer layer pipe. The bottom end and the top end of the mold are respectively provided with a bottom plate and a top plate, and the top plate and the bottom plate cover the top end opening and the bottom end opening of the outer layer pipe respectively. The application also provides a ceramic filter tube which comprises a support body, an intermediate layer and a surface coating layer. The support body is a hollow pipe structure, the outer pipe wall of the support body is provided with an outward protrusion, and the top end of the support body is provided with an annular flange face. The intermediate layer covers the outer pipe wall of the support body, and the thickness of the intermediate layer is uniform. The surface coating layer covers the surface of the intermediate layer, and the thickness of the surface coating layer is uniform. The application also provides a preparation method of the ceramic filter tube and a dust removal and denitration integrated ceramic filter tube comprising the ceramic filter tube.

Description

Technical Field

[0001] This invention relates to the technical field of end-of-pipe denitrification and dust removal equipment for waste gas treatment, and particularly to a filter tube mold, a ceramic filter tube and its preparation method, and an integrated ceramic filter tube for dust removal and denitrification. Background Technology

[0002] Currently, most waste gas denitrification, desulfurization, and dust removal processes employ separate, series-connected equipment for each stage. This results in complex and large-scale systems with high initial investment costs. Furthermore, the flue gas temperature is low after desulfurization and dust removal. If desulfurization and dust removal are performed before denitrification, air heating equipment is required, increasing operating costs. Conversely, if denitrification is performed first, the catalyst suffers severe dust abrasion and sulfur poisoning, significantly shortening its lifespan.

[0003] The concept of integrated denitrification, desulfurization, and dust removal was proposed as early as the 20th century. Extensive experiments on integrated processes were conducted in the 1970s, yielding some results. Integrated processes such as the sodium chlorite method, activated coke method, ozone oxidation method, and plasma method were all achievable in the laboratory, but each had its drawbacks. The sodium chlorite method introduces chloride ions into the desulfurization ash or slurry, which is detrimental to byproduct enrichment; the activated coke method has relatively low overall efficiency, is only suitable for low pollutant concentration conditions, and requires strict control of flue gas temperature; the ozone oxidation method's ozone generation and leakage issues still restrict its industrial application; the plasma method shares some commonalities with ozone oxidation in principle, and the laboratory process is relatively mature, but it still has few practical engineering applications.

[0004] Ceramic filter tubes are a new type of dust removal material that has emerged in recent years. They overcome the problem of low temperature resistance of traditional bag filters and are extremely suitable for integration with denitrification equipment. However, existing ceramic filter tubes are often expensive and heavy, making it inconvenient to design them to be as long as filter bags, resulting in a smaller filtration area, making them only suitable for small-volume dust removal. In addition, the ceramic fiber pores inside the filter tube are tiny and dense, making it easy to clog the filter tube if denitrification catalysts are directly loaded onto it. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a filter tube mold, a ceramic filter tube and its preparation method, and an integrated dust removal and denitrification ceramic filter tube. This ceramic filter tube has a layered structure and raised surfaces, which effectively increases the filtration surface area while saving raw materials, thereby improving dust removal and denitrification efficiency.

[0006] To achieve the above objectives, the present invention provides a filter tube mold, wherein the filter tube mold includes an inner tube and an outer tube, the inner tube being a hollow tube, and the outer tube having two or more outwardly protrusions on its outer wall, the protrusions being hollow structures; an annular space is formed between the inner tube and the outer tube for injecting slurry; a bottom plate is provided at the bottom end of the mold, and a top plate is provided at the top end of the mold, the top plate and the bottom plate respectively covering the top opening and the bottom opening of the outer tube.

[0007] In the above-mentioned filter tube mold, by adding a protruding structure to the outer surface of the mold, the outer surface area of ​​the filter tube can be increased, thereby increasing the filtration area of ​​the mold and solving the problem that the filtration area of ​​conventional filter tubes is too small due to the rigid structure that makes it unsuitable to design them to be too long.

[0008] According to a specific embodiment of the present invention, both the inner tube and the outer tube may be open at both ends. The inner tube and the outer tube are generally coaxially arranged.

[0009] According to specific embodiments of the present invention, the protrusions located on the outer tube can be circular, square, conical, or polygonal. In some specific embodiments, multiple consecutive protrusions form a corrugated pattern on the side surface of the filter tube mold (e.g., Figure 2 (As shown in I).

[0010] According to a specific embodiment of the present invention, the top plate covers the top opening of the inner tube and the top of the annular space between the inner tube and the outer tube. Correspondingly, the bottom plate covers the bottom opening of the inner section and the bottom of the annular space between the inner tube and the outer tube.

[0011] According to a specific embodiment of the present invention, the cross-sections of the inner tube and the top plate can be centrally symmetrical shapes such as circles, squares, and rhombuses.

[0012] According to a specific embodiment of the present invention, when the cross-sections of the inner tube and the top plate are both circular, such as Figure 2 As shown in I and II, the diameter 'a' of the top plate is generally controlled to be 100mm-300mm, and the ratio of the diameter 'c' of the inner tube (i.e., the inner diameter of the inner tube; the wall thickness of the inner tube is ignored in this invention) to the diameter of the top plate is generally 0.5-0.8:1. When the cross-sections of the inner tube and the top plate are other centrally symmetric shapes besides circles, the dimensions of the top plate and the dimensional relationship between the top plate and the inner tube are similar to those described above.

[0013] According to a specific embodiment of the present invention, when the cross-section of the inner tube is circular, at the same horizontal height, the distance between the apex of the protrusion of the outer tube and the center of the cross-section of the inner tube is denoted as m, and the radius of the inner tube is denoted as n. m is generally controlled to be between (n+5mm) and (n+50mm). When the cross-section of the inner tube is a centrally symmetric shape other than a circle, the dimensional relationship between the protrusion of the outer tube and the inner tube is similar to that described above.

[0014] According to a specific embodiment of the present invention, the height of the protrusions at the same horizontal level can be the same; for example, the highest point of each protrusion at the same horizontal level can be located on the same circumference.

[0015] According to a specific embodiment of the present invention, when the cross-section of the inner tube is circular and the apexes of the protrusions at the same horizontal height are located on the same circumference, such as Figure 2 As shown in I and II, the diameter b of the circumference where the apex of the protrusion is located is 10 mm to 100 mm larger than the diameter c of the inner tube.

[0016] According to a specific embodiment of the present invention, such as Figure 2 As shown in I and II, along the axial direction of the filter tube mold, the vertical width d of each protrusion of the outer tube is generally controlled to be 20mm-50mm.

[0017] According to a specific embodiment of the present invention, when the filter tube mold is used to prepare ceramic filter tubes, considering that ceramic filter tubes are rigid materials and more brittle than traditional bag filter media, the total length e of the filter tube mold is generally controlled to be within 3m (e.g., Figure 2 (As shown in I).

[0018] This invention further provides the application of the above-mentioned filter tube mold in the preparation of filter tubes, especially in the preparation of ceramic filter tubes. When using the above-mentioned filter tube mold to prepare filter tubes, the top and bottom plates of the mold are generally opened, and the slurry is injected from the top of the mold into the annulus between the inner and outer tubes. A suction filtration device is set below the bottom plate to suction and shape the slurry. The filter tube prepared by this filter tube mold is generally a hollow tube with a length of less than 3m. The top plate of the filter tube mold forms the flange face of the filter tube, which covers the tube wall of the support body. The outer diameter of the flange face is 100mm-300mm, and the inner diameter of the hollow tube body is 0.5-0.8 times the outer diameter of the flange face. The outer surface of the hollow tube body is provided with vertical protrusions with a width of 20mm-50mm. The distance from the apex of each protrusion at the same horizontal height to the center of the cross-section of the hollow tube body is 10mm-100mm.

[0019] The present invention further provides a ceramic filter tube, which includes a support body, an intermediate layer and a surface coating layer, wherein: the support body is a hollow tube structure, the outer tube wall of the support body is provided with two or more outward protrusions, the top end of the support body is provided with an annular flange surface, the flange surface covers the top end section of the tube wall of the support body; the intermediate layer covers the surface of the outer tube wall of the support body; and the surface coating layer covers the surface of the intermediate layer.

[0020] The ceramic filter tube provided by this invention has a layered structure, consisting of a surface coating layer, an intermediate layer, and a support body from the outside in. The support body, located in the inner layer, has a porous structure, facilitating catalyst loading and dispersion. The intermediate layer has a relatively dense structure and can be used as a dust removal layer. The intermediate layer, in conjunction with the support body, can reduce the pressure loss of the ceramic filter tube and decrease dust clogging. The surface coating layer is resistant to acid and alkali corrosion and can reduce dust accumulation at the joints of the protrusions in the ceramic filter tube, as well as reduce clogging of the pores between the intermediate and inner layers. The three layers of the ceramic filter tube work synergistically in structure and function, improving the filtration and catalytic functions of the ceramic filter tube in dust removal and denitrification. According to a specific embodiment of this invention, by providing protrusions on the surface of the support body, the specific surface area of ​​the support body can be increased. Furthermore, by controlling the uniform thickness of the intermediate layer and the surface coating layer, the protrusion structure on the outer surface of the ceramic filter tube can be retained, thereby increasing the overall filtration area of ​​the ceramic filter tube.

[0021] According to specific embodiments of the present invention, the thickness of the intermediate layer is generally controlled to be 10mm-40mm. In some specific embodiments, the thickness of the intermediate layer is generally uniform in order to retain the raised structure on the surface of the support.

[0022] According to a specific embodiment of the present invention, the thickness of the surface coating layer is generally controlled to be 50μm-200μm. The thickness of the surface coating layer is generally uniform in order to preserve the raised structure of the support surface.

[0023] According to a specific embodiment of the present invention, in the above-mentioned ceramic filter tube, the support body can have a structural correspondence with the above-mentioned filter tube mold. The specific correspondence can be as follows: the wall thickness of the support body corresponds to the radial dimension of the annular space between the inner tube and the outer tube in the filter tube mold; the protrusions on the outer tube wall of the support body correspond to the protrusion structure in the filter tube mold; the inner wall of the flange surface of the support body is flush with the inner tube wall of the support body, and the outer wall of the flange surface corresponds to the outer edge of the top plate in the filter tube mold.

[0024] According to a specific embodiment of the present invention, the support body is a hollow tube structure with a hollow portion; the flange face is an annular structure, which also has a hollow portion. In some specific embodiments, the cross-sections of the hollow portions of the support body and the flange face can be circular, square, rhomboid, or other centrally symmetrical shapes.

[0025] According to a specific embodiment of the present invention, in the support body, when the cross-sections of the hollow portion of the support body and the hollow portion of the flange face are circular, the outer edge of the flange face is also correspondingly circular. The outer diameter of the flange face is generally 100mm-300mm, and the ratio of the inner diameter of the support body (i.e., the cross-sectional diameter of the hollow portion of the support body) to the outer diameter of the flange face is generally 0.5-0.8:1. When the cross-sections of the hollow portion of the support body and the hollow portion of the flange face are other centrally symmetric figures, the dimensions of the flange face and the dimensional relationship between the support body and the flange face are similar to those described above.

[0026] According to a specific embodiment of the present invention, in the support body, when the cross-section of the hollow part is circular, at the same horizontal height, the distance from the apex of the protrusion on the outer tube wall to the center of the cross-section of the support body is generally 5mm-50mm larger than the inner diameter of the support body.

[0027] According to a specific embodiment of the present invention, at the same horizontal height, the distance from each protrusion to the center of the cross-section of the hollow portion of the support can be equal. For example, when the cross-section of the hollow portion of the support is circular, the highest point of each protrusion at the same horizontal height is generally located on the same horizontal circumference. In this case, the diameter of the circumference where the apex of each protrusion is located is 10 mm to 100 mm larger than the inner diameter of the support.

[0028] According to a specific embodiment of the present invention, in the support body, the vertical width of each protrusion is generally 20mm-50mm.

[0029] According to a specific embodiment of the present invention, due to the high brittleness of ceramic materials, the overall length of the ceramic filter tube should not be too long, generally controlled within 3m. The present invention increases the filtration area of ​​the ceramic filter tube by setting protrusions on its surface, thereby effectively solving the problem of small filtration area caused by the length limitation of the ceramic filter tube.

[0030] According to specific embodiments of the present invention, in the above-mentioned ceramic filter tube, the support has a high porosity, which can be used to load catalysts to achieve reactions such as denitration. In some specific embodiments, the porosity of the support can generally reach 50%-70%. The pore size of the support is generally 2μm-3μm.

[0031] According to a specific embodiment of the present invention, in the above-mentioned ceramic filter tube, the support body also has high mechanical strength. In some specific embodiments, the compressive strength of the support body can reach 0.5GPa-3GPa, and the bending strength of the support body can reach 95MPa-130MPa.

[0032] According to a specific embodiment of the present invention, in the above-mentioned ceramic filter tube, the structure of the intermediate layer is more compact than that of the support. The average porosity of the intermediate layer and the support is generally 30%-50%, and the average pore size of the intermediate layer and the support is 5μm-15μm.

[0033] According to a specific embodiment of the present invention, the ceramic filter tube provided by the present invention has high mechanical properties. The compressive strength of the ceramic filter tube can reach 2.5GPa-3.5GPa, for example, 3GPa-3.5GPa, and the flexural strength of the ceramic filter tube can reach 195MPa-400MPa, for example, 200MPa-400MPa or 300MPa-400MPa.

[0034] The present invention also provides a method for preparing a ceramic filter tube, which can be used to prepare the above-mentioned ceramic filter tube, and the method includes:

[0035] S1. Alumina fibers and aluminosilicate fibers are mixed at a mass ratio of 10:0-5:5, then a coagulant is added to form a fiber slurry. A dispersant is then added, and the mixture is stirred and the pH is adjusted to 8-10 to obtain the first slurry. This first slurry is used as the raw material for preparing the support.

[0036] Aluminum nitrate solution is mixed with aluminum powder and heated to obtain aluminum sol; the aluminum sol is filtered, then boehmite and spinning aid are added, and the mixture is concentrated to obtain a second slurry; this second slurry is used as the raw material for preparing the intermediate layer;

[0037] A first nano-alumina, polyethersulfone, isopropanol, N-methylpyrrolidone, and glycerol are mixed in a ratio of 40-60:5-10:0.5-2:30-50:0.15-0.3 to obtain an intermediate slurry. Then, a second nano-alumina is added, with the mass of the second nano-alumina being 15%-25% (e.g., 20%) of the mass of the intermediate slurry, to obtain a third slurry. This third slurry is used as the raw material for preparing the surface coating layer.

[0038] S2. Using the above-mentioned filter tube mold as a mold, the first slurry is injected into the annulus between the inner and outer tubes of the filter tube mold, and the mixture is drawn and shaped. The first slurry in the filter tube mold is dried to obtain a blank, and the blank is calcined to obtain a support.

[0039] S3. Using the support obtained in S2 as a spinning roller, the second slurry is spun on the surface of the support at a spraying speed of 5L / min-20L / min, dried, and calcined to form an intermediate layer covering the surface of the support.

[0040] S4. Encapsulate the inner side of the support obtained in S3, immerse the encapsulated support with the middle layer on the surface in the third slurry, remove the immersed support, dry it, and calcine it to obtain the ceramic filter tube.

[0041] According to a specific embodiment of the present invention, in S1, during the preparation of the first slurry, the lengths of the alumina fibers and aluminum silicate fibers are generally 2-10 μm.

[0042] According to a specific embodiment of the present invention, in S1, the mass ratio of alumina fiber to aluminum silicate fiber of 10:0-5:5 means that alumina fiber can be added only in the first slurry without aluminum silicate fiber, or alumina fiber and aluminum silicate fiber with a mass ratio greater than 10:0 and less than or equal to 5:5 can be added simultaneously.

[0043] According to a specific embodiment of the present invention, in S1, the aluminum in the alumina fibers in the first slurry can serve as aggregate for the subsequently formed support, giving the support higher mechanical strength. When the first slurry contains aluminosilicate fibers, the aluminum and silicon in the aluminosilicate fibers can also serve as aggregate for the support, improving the mechanical properties of the support.

[0044] According to a specific embodiment of the present invention, in S1, during the preparation of the first slurry, the coagulant may include one or more of water glass, silica sol, alumina sol, aluminum phosphate, organic solvents, etc.

[0045] According to a specific embodiment of the present invention, in S1, during the preparation of the first slurry, the mass concentration of the fiber slurry is generally 15%-35%. That is, the total mass of alumina fiber and aluminosilicate fiber is 15%-35% of the mass of the fiber slurry.

[0046] According to a specific embodiment of the present invention, in S1, during the preparation of the first slurry, the mass of the dispersant is generally 0.1%-0.5% of the mass of the fiber slurry. In some specific embodiments, the dispersant may include glycerol, etc.

[0047] According to a specific embodiment of the present invention, in S1, during the preparation of the first slurry, the stirring time after adding the dispersant is generally controlled to be 30 min to 2 h.

[0048] According to a specific embodiment of the present invention, in S1, the reagent used to adjust the pH value during the preparation of the first slurry can be a sodium hydroxide solution or the like.

[0049] According to a specific embodiment of the present invention, in step S1, a second slurry is prepared by the sol-gel method. This second slurry is an outer ceramic fiber slurry and is the raw material slurry for the continuous fiber spinning process in step S3.

[0050] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the mass concentration of the aluminum nitrate solution is generally controlled to be 5g / 100g-35g / 100g. The aluminum nitrate solution generally refers to an aqueous solution of aluminum nitrate.

[0051] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the mass of the aluminum powder is generally 10%-25% of the mass of the aluminum nitrate solution.

[0052] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, by controlling the particle size of the aluminum powder and boehmite, the dispersion degree of suspended matter in the second slurry can be improved, thereby controlling the porosity and pore size of the intermediate layer formed by the second slurry. The average particle size of the aluminum powder is less than or equal to 5 μm.

[0053] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the average particle size of the boehmite is less than or equal to 2 μm.

[0054] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the heating temperature for preparing the aluminum sol is generally controlled at 82-98°C, for example 90°C, and the heating time is generally controlled at 7-10h, for example 8h.

[0055] According to a specific embodiment of the present invention, in S1, before adding boehmite to the alumina sol during the preparation of the second slurry, the process generally includes a step of vacuum filtering the alumina sol to obtain a filtrate. Then, the boehmite is added to the filtrate.

[0056] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the mass of the boehmite is generally 0.5%-3% of the mass of the alumina sol (preferably the filtrate obtained by vacuum filtration of the alumina sol).

[0057] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the mass of the spinning aid is generally 5%-12% of the mass of the aluminum sol (preferably the filtrate obtained by vacuum filtration of the aluminum sol).

[0058] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the spinning aid may include polyvinylpyrrolidone, etc.

[0059] According to a specific embodiment of the present invention, in S1, during the preparation of the second slurry, the concentration operation is used to form a slurry with suitable viscosity that can be used in a continuous fiber spinning process. The viscosity of the second slurry obtained after concentration is generally controlled to be 200 Pa·s-550 Pa·s. In some specific embodiments, the concentration can be carried out by means of rotary evaporation or the like.

[0060] According to a specific embodiment of the present invention, in S1, during the preparation of the third slurry, the first nano-alumina and the second nano-alumina can use the same alumina. Adding the alumina in two batches, one before and one after the formation of the intermediate slurry, can achieve a balance between the number of crystal nuclei and the crystallization rate. In some specific embodiments, the average particle size of the first nano-alumina and the second nano-alumina is generally less than or equal to 30 nm.

[0061] According to a specific embodiment of the present invention, in S1, during the preparation of the third slurry, the intermediate slurry can be stirred for 2-4 hours before adding the second nano-alumina. Preferably, the second nano-alumina can be added to the intermediate slurry in stages to control the grain size. The number of stages can be 3-5, with an interval of 2-4 hours between each addition, and the amount added each time can be equal. After the last addition of the second nano-alumina, stirring is maintained for 2-4 hours to obtain the third slurry.

[0062] According to a specific embodiment of the present invention, step S2 involves injecting a first slurry containing short fibers into a filter tube mold and then suction molding it to obtain a support with protrusions on its surface. The dimensions of the support are substantially consistent with the corresponding dimensions of the filter tube mold.

[0063] According to a specific embodiment of the present invention, the specific process of suction molding may include: opening the top plate and bottom plate of the filter tube mold, pouring the first slurry from the top plate along the annulus between the outer tube and the inner tube of the mold, setting a suction filtration device at the bottom plate outlet for suction, the suction process can reduce the pores in the slurry, and when the first slurry is observed to be viscous, it indicates that there are almost no air bubbles in the slurry, at which point the suction filtration can be stopped, and finally the suction-molded slurry is obtained.

[0064] According to a specific embodiment of the present invention, in S2, the drying temperature can be controlled to be 105℃-120℃, and the drying time can be controlled to be 12h-48h.

[0065] According to a specific embodiment of the present invention, in S2, the calcination temperature can be controlled to be 1000℃-1450℃, the calcination time can be controlled to be 5min-60min, and the calcination can be carried out in an air atmosphere. The heating rate of the calcination process can be controlled to be 3℃ / min-5℃ / min.

[0066] According to a specific embodiment of the present invention, step S3 involves uniformly winding fiber filaments on the surface of the support through a continuous fiber spinning process to form a relatively dense intermediate layer, the thickness of which is generally controlled to be 10mm-40mm.

[0067] According to a specific embodiment of the present invention, in S3, by controlling the spraying speed of the second slurry onto the surface of the spinning roller to be 5L / min-20L / min, it can be ensured that the fiber filaments formed by the second slurry are continuously wrapped around the surface of the spinning roller, thereby achieving uniform winding of the fiber filaments on the surface of the fiber tube and obtaining a uniform thickness intermediate layer.

[0068] According to a specific embodiment of the present invention, in S3, the speed of the spinning roller (i.e., the support obtained in S2) is generally controlled to be 100m / min-150m / min.

[0069] According to a specific embodiment of the present invention, the calcination process in S3 generally adopts a segmented calcination method to effectively protect the porous structure of the support. The calcination process generally includes: raising the temperature to 250℃-400℃ at a rate of 2℃ / min-4℃ / min, holding for 1h-3h, then raising the temperature to 650℃-900℃ at a rate of 2℃ / min-4℃ / min, holding for 1h-3h, and finally raising the temperature to 1000℃-1450℃ at a rate of 3℃ / min-5℃ / min, holding for 3min-30min to complete the calcination. The short holding time in the high-temperature section of the above calcination process can suppress excessively large grains in the support, thereby protecting the porous structure of the support and preventing clogging of the ceramic filter tube.

[0070] According to a specific embodiment of the present invention, in S4, the immersion time can be controlled to be 3-5 minutes.

[0071] According to a specific embodiment of the present invention, in S4, the heating rate of the calcination can be controlled to be 3℃ / min-5℃ / min, the calcination temperature can be controlled to be 1200℃-1350℃, for example 1200℃-1300℃, and the calcination time can be controlled to be 5min-10min.

[0072] According to a specific embodiment of the present invention, the preparation method of the above-mentioned ceramic filter tube may specifically include the following process:

[0073] S1. Alumina fibers and aluminosilicate fibers are mixed at a mass ratio of 10:0-5:5, and cut into short fibers of 2μm-10μm. Then, a solution formed by a silicon source and / or an aluminum source and an organic solvent is added and stirred to obtain a fiber slurry with a mass concentration of 15%-35%. Next, a dispersant of 0.1%-0.5% of the fiber slurry mass is added to the fiber slurry, and the mixture is stirred for 30 minutes to 2 hours. The pH value is adjusted to 8-10 to obtain the first slurry. This first slurry is used as the raw material for preparing the support.

[0074] An aluminum nitrate solution with a concentration of 5 g / 100 g to 35 g / 100 g was mixed with aluminum powder, the average particle size of which was ≤5 μm and the mass of which was 10% to 25% of the mass of the aluminum nitrate solution. The mixture was heated at 90°C for 8 hours to obtain an aluminum sol. The aluminum sol was then filtered to obtain a filtrate. Boehmite and a spinning aid were then added to the filtrate, the average particle size of which was ≤2 μm and the mass of which was 0.5% to 3% of the mass of the filtrate. The mass of the spinning aid was 5% to 12% of the mass of the filtrate. The mixture was then concentrated by rotary evaporation to obtain a second slurry with a viscosity of 200 Pa·s to 550 Pa·s. This second slurry was used as the raw material for preparing the intermediate layer.

[0075] First nano-alumina (average particle size ≤30nm), polyethersulfone, isopropanol, N-methylpyrrolidone, and glycerol are mixed in a ratio of 40-60:5-10:0.5-2:30-50:0.15-0.3 and stirred for 2-4 hours to obtain an intermediate slurry. While maintaining stirring, second nano-alumina (average particle size ≤30nm) is added to the intermediate slurry in 3-5 portions. The total mass of the second nano-alumina is 20% of the mass of the intermediate slurry. The mass of the second nano-alumina added each time is equal, and the interval between each addition is 2-4 hours. After the last addition of the second nano-alumina, stirring is maintained for 2-4 hours to obtain a third slurry. This third slurry is used as the raw material for preparing the surface coating layer.

[0076] S2. Using the above-mentioned filter tube mold as a mold, open the top plate and bottom plate of the filter mold, and inject the first slurry from top to bottom into the annulus between the inner and outer tubes of the filter tube mold. Set up a suction filter below the bottom plate to suction and shape the first slurry. Dry the first slurry in the filter tube mold under the drying conditions of 105℃-120℃ for 12h-48h to obtain a blank. Take the blank out of the filter tube mold and calcine the blank in an air atmosphere at 1000℃-1450℃ for 5min-60min to obtain a support with a porous structure.

[0077] S3. Using the support obtained in S2 as a spinning roller, the linear speed of the spinning roller is kept at 100m / min-150m / min, and the second slurry is spun on the surface of the support at a spraying speed of 5L / min-20L / min. The slurry is dried at 105℃-120℃ and calcined in sections to form an intermediate layer covering the surface of the support. The thickness of the intermediate layer is generally 10mm-40mm.

[0078] The segmented calcination process is as follows: the temperature is increased to 250℃-400℃ at a rate of 2-4℃ / min and held for 1-3 hours; then the temperature is increased to 650℃-900℃ at a rate of 2-4℃ / min and held for 1-3 hours; finally, the temperature is increased to 1000℃-1450℃ at a rate of 3-5℃ / min and held for 3-30 minutes to complete the calcination.

[0079] S4. Encapsulate the inner side of the support obtained in S3, immerse the encapsulated support in the third slurry for 3-5 minutes, remove the immersed support and dry it at 105℃-120℃, then calcine it at 1200-1350℃ at a rate of 3-5℃ / min for 5-10 minutes to form a 50μm-200μm thick surface coating layer on the surface of the intermediate layer, and cool it to room temperature to obtain the ceramic filter tube.

[0080] This invention further provides an integrated ceramic filter tube for dust removal and denitrification, comprising the aforementioned ceramic filter tube. When the ceramic filter tube of this invention is applied to a dust removal and denitrification process, a catalyst is generally dispersed and loaded in the support of the ceramic filter tube for the denitrification reaction; the intermediate layer of the ceramic filter tube, through its dense structure, can effectively remove dust and, in conjunction with the support, reduce the pressure loss of the ceramic filter tube, alleviating dust clogging; the surface coating layer of the ceramic filter tube prevents acid and alkali corrosion and can prevent dust accumulation at the protruding joints (as opposed to protrusions and depressions), and also prevents clogging of the through holes in the filter tube. In some specific embodiments, the dust removal efficiency of the ceramic filter tube can reach over 98%, or even over 99%, and the denitrification efficiency of the ceramic filter tube can reach over 95%.

[0081] The beneficial effects of this invention are as follows:

[0082] 1. The ceramic filter tube provided by this invention, by setting protrusions on its surface, can effectively increase the filtration area while saving manufacturing materials, thus overcoming the defect of limited filtration area caused by the length limitation of ceramic filter tubes. It is suitable for large-volume dust removal and can effectively reduce the number of filter tubes used in large flue gas conditions. Correspondingly, by setting a surface coating layer in the ceramic filter tube, this invention can effectively reduce the accumulation of dust at the joint of the protrusions.

[0083] 2. The ceramic filter tube provided by the present invention has an inner and outer layered structure, which can effectively alleviate the problem of excessive pressure loss and easy clogging of dense ceramic filter material during dust removal; the support body located in the inner layer has a porous structure, which can load and disperse more catalyst, thereby improving the denitrification effect of the ceramic filter tube, which is of positive significance for realizing the integration of dust removal and denitrification processes. Attached Figure Description

[0084] Figure 1 This is a schematic diagram of the external structure of the filter tube mold in Example 1.

[0085] Figure 2 The figures show a cross-sectional view and an AA section view of the filter tube mold in Example 1.

[0086] Figure 3 This is a cross-sectional view of the ceramic filter tube in Example 1.

[0087] Figure 4 This is a cross-sectional view of the ceramic filter tube in Example 2 at the protrusion.

[0088] Figure 5 The test results are for the surface porosity and pore size of ceramic filter tubes without surface coating.

[0089] Figure 6 The test results show the compressive and flexural strength of the support.

[0090] Figure 7 The results show the surface porosity and average pore size of the support.

[0091] Figure 8 The results are from the dust removal test of the ceramic filter tube.

[0092] Figure 9 The results show the compressive and flexural strength of the ceramic filter tube.

[0093] Symbol Explanation

[0094] Inner tube 1, outer tube 2, top plate 3, bottom plate 4, support 10, intermediate layer 20, surface coating layer 30.

[0095] a is the diameter of the top plate, b is the diameter of the circumference of the apex of the protrusions at the same horizontal height, c is the diameter of the inner tube, d is the vertical width of each protrusion along the axial direction, e is the length of the filter tube mold, and f is the circumference formed by the connection of the protrusions at the same horizontal height. Detailed Implementation

[0096] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0097] Example 1

[0098] This embodiment provides a filter tube mold. Figure 1 This is a schematic diagram of the external structure of the filter tube mold, where I is the front view of the filter tube mold and II is a schematic diagram of the structure after raising the viewing angle compared to the front view. Figure 2 The diagram shows a cross-sectional view (I) and section AA (II) of the filter tube mold along its central axis. Section AA is located at... Figure 1 The 'I' in the diagram is shown. Figure 3 This is a cross-sectional view of the middle section of the filter tube mold, showing two different structures where protrusions can be installed.

[0099] like Figure 1 and Figure 2 As shown, the filter tube mold includes an inner tube 1 and an outer tube 2, with the outer tube 2 located outside the inner tube 1, and the two are coaxially arranged. The filter tube mold also includes a top plate 3 and a bottom plate 4.

[0100] Both the inner tube 1 and the outer tube 2 are hollow tubes, and their two ends are connected respectively. The top ends of the inner tube 1 and the outer tube 2 are connected to each other, and the top plate 3 covers the top opening of the outer tube 2 (including covering the top end of the annular space between the outer tube 2 and the inner tube 1 and the top opening of the inner tube 1); the bottom ends of the inner tube 1 and the outer tube 2 are connected to each other, and the bottom plate 4 covers the bottom opening of the outer tube 2 (including covering the bottom end of the annular space between the outer tube 2 and the inner tube 1 and the bottom opening of the inner tube 1).

[0101] The outer tube 2 has multiple continuous protrusions extending outward from its surface on its outer wall. These protrusions connect on the outer surface of the outer tube 2 to form a wave-like shape, such as... Figure 2 As shown in Figure I; when viewed along the cross-section of the outer tube 2, the apexes of the protrusions at the same horizontal height connect to form a circle, as shown in Figure I. Figure 2 As shown in II. In Figure 1 , Figure 2 In the specific embodiment shown, the protrusion of the outer tube 2 can be a complete annular protrusion formed in the horizontal direction, with multiple annular protrusions stacked along the axial direction of the outer tube 2, such as... Figure 3 As shown in I; while in other specific implementation schemes, such as Figure 3 As shown in II, the protrusions of the outer tube 2 can also be a flower-shaped ring formed by multiple protrusions of the same size along the horizontal direction, with the apexes of the multiple protrusions located on the same circumference (corresponding to a diameter of b) and the connection points of the multiple protrusions located on the same circumference f.

[0102] Figure 2In this diagram, 'a' represents the diameter of the top plate 3, 'b' represents the diameter of the circumference of the apex of each protrusion at the same horizontal height, 'c' represents the diameter of the inner tube 1, 'd' represents the vertical width of each protrusion (along the axial direction of the outer tube 2), 'e' represents the length of the filter tube mold, and 'f' represents the circumference formed by the connection of the protrusions at the same horizontal height. The diameter 'a' of the top plate 3 is 100mm-300mm; the ratio of the diameter 'c' of the inner tube 1 to the diameter 'a' of the top plate 3 is 0.5-0.8:1; the difference between the diameter 'b' of the circumference of the apex of each protrusion at the same horizontal height and the diameter 'c' of the inner tube is 10mm-100mm, i.e., 'b' is (c+10mm) to (c+100mm); the vertical width 'd' of each protrusion is 20mm-50mm; and the length 'e' of the filter tube mold is ≤3m.

[0103] Example 2

[0104] This embodiment provides a method for preparing a ceramic filter tube. The filter mold used in this method has the same structure as the filter mold in Embodiment 1, except that the dimensions of the filter mold used in this embodiment are as follows: the diameter a of the top plate 3 is 150 mm; the diameter b of the circumference of the apex of the protrusion at the same horizontal height is 125 mm; the diameter c of the inner tube 1 is 90 mm; the vertical width d of each protrusion is 20 mm; the length e of the filter tube mold is 1515 mm; and the cross-section of the filter mold along the horizontal direction is as shown below. Figure 3 As shown in I.

[0105] The preparation method of this embodiment includes the following steps:

[0106] S1. Raw materials for preparing the support: Alumina fibers and aluminosilicate fibers are mixed at a mass ratio of 8.5:1.5, cut into short fibers of 7μm, and then silica sol is added and stirred to obtain a fiber slurry with a mass concentration of 25% (i.e., the sum of the mass percentages of alumina fibers and aluminosilicate fibers in the fiber slurry is 25%). Glycerol at a mass of 0.25% of the fiber slurry mass is added as a dispersant, stirred for 1 hour, and a small amount of sodium hydroxide solution is added dropwise to adjust the pH value to 8.5 to obtain the first slurry.

[0107] Raw materials for preparing the intermediate layer: Aluminum nitrate solution with a concentration of 30 g / 100 g was mixed with aluminum powder with an average particle size of 1 μm, the mass of aluminum powder being 22% of the mass of aluminum nitrate solution. The mixture was heated at 90 °C for 8 h to obtain aluminum sol. The aluminum sol was filtered to obtain filtrate. Boehmite and spinning aid polyvinylpyrrolidone were then added to the filtrate. The average particle size of boehmite was 1 μm, the mass of boehmite being 1.5% of the mass of the filtrate, and the mass of spinning aid being 8% of the mass of the filtrate. The mixture was stirred and concentrated in a rotary evaporator at 40 °C to obtain a second slurry with a viscosity of 450 Pa·s.

[0108] Raw materials for preparing the surface coating layer: Nano-alumina with an average particle size of 23 nm, polyethersulfone, isopropanol, N-methylpyrrolidone and glycerol are mixed in a ratio of 50:8:1:40.7:0.3 and stirred for 2.5 h to obtain an intermediate slurry; while maintaining the stirring state, nano-alumina with an average particle size of 23 nm is added to the intermediate slurry in 4 portions. The total mass of the second nano-alumina is 20% of the mass of the intermediate slurry. The mass of the second nano-alumina added each time is equal, and the interval between each addition is 2.5 h. After the last addition of the second nano-alumina, the mixture is stirred for 3.5 h to obtain the third slurry.

[0109] S2. Open the top and bottom plates of the filter mold, and inject the first slurry from top to bottom into the annulus between the inner and outer tubes of the filter tube mold. Set up a suction filter under the bottom plate to suction and shape the first slurry. Dry the first slurry in the filter tube mold at 105℃-120℃ for 24 hours to obtain a preform. Take the preform out of the filter tube mold and calcine it at 1350℃ for 10 minutes in an air atmosphere to obtain a support with a porous structure.

[0110] S3. Using the support obtained in S2 as a spinning roller, the linear speed of the spinning roller is kept at 140 m / min, and the second slurry is spun on the surface of the support at a spraying speed of 12 L / min. The slurry is dried at 105°C and calcined in sections to form an intermediate layer covering the surface of the support; the thickness of the intermediate layer is 20 μm.

[0111] The segmented calcination process is as follows: in a muffle furnace, the temperature is raised to 400℃ at a rate of 3℃ / min and held for 2 hours, then raised to 800℃ at a rate of 3℃ / min and held for 2 hours, and finally raised to 1350℃ at a rate of 5℃ / min and held for 5 minutes to complete the calcination.

[0112] S4. The inner side of the support obtained in S3 is encapsulated with an inorganic membrane material. The encapsulated support is immersed in the third slurry and kept immersed in an ultrasonic cleaner for 3 minutes. After the support is removed, it is dried at 105°C and calcined at 1350°C at a rate of 4°C / min for 8 minutes to form a 100μm thick surface coating layer on the surface of the intermediate layer. After cooling to room temperature, a ceramic filter tube is obtained.

[0113] The ceramic filter tube obtained in this embodiment consists of a support body 10, an intermediate layer 20, and a surface coating layer 30. The support body 10 is a hollow tube structure with outward protrusions on its outer wall and an annular flange at its top. The outer diameter of the flange of the support body 10 is 150 mm; the diameter of the circumference of the protrusions at the same horizontal height is 125 mm; the inner diameter of the support body 10 is 90 mm; the vertical width of each protrusion along the axis of the support body 10 is 20 mm; and the total length of the support body 10 is 1515 mm.

[0114] Figure 4 This is a cross-sectional view of the ceramic filter tube at the protrusion. (See diagram below.) Figure 4 As shown, the intermediate layer 20 covers the surface of the outer tube wall of the support 10, and the thickness of the intermediate layer 20 is the same everywhere, thus the intermediate layer 20 retains the protruding structure of the support 10. The thickness of the intermediate layer 20 is 20 μm.

[0115] The surface coating layer 30 covers the surface of the intermediate layer 20, and the thickness of the surface coating layer 30 is the same throughout, thus the surface coating layer 30 retains the raised structure of the intermediate layer 20 and the support 10. The thickness of the surface coating layer 30 is 100 μm.

[0116] The average diameter of the fibers in the ceramic filter tube obtained above was measured by TEM, and the average diameter of the fibers in the ceramic filter tube was found to be 14.56 μm.

[0117] Test Example 1

[0118] This test example is a test of the pore structure and mechanical properties of the ceramic filter tube of the present invention.

[0119] The test methods are as follows: pore size is measured by BET nitrogen adsorption method, surface porosity is measured according to GB / T1966-80 "Test Method for Apparent Porosity and Bulk Density of Porous Ceramics", and compressive strength and flexural strength are measured by three-point bending method on a universal testing machine.

[0120] The surface porosity and pore size of ceramic filter tubes without a surface coating were tested, and the results are as follows: Figure 5 As shown. The calcination temperatures during the preparation of the support for the ceramic filter tube under test were 1250℃, 1300℃, 1350℃, 1400℃, and 1450℃, respectively. Other preparation parameters for the support and intermediate layer were the same as in Example 2, including the mass ratio of alumina fiber to aluminosilicate fiber in the first slurry being 8.5:1.5.

[0121] like Figure 5As shown, by adjusting the calcination temperature of the first slurry, the pore structure of the support can be affected, thereby adjusting the pore structure of the ceramic filter tube. When the calcination temperature is 1350℃, the surface porosity of the ceramic filter tube without the surface coating layer can reach 36.8%, and the average pore diameter of the ceramic filter tube (i.e., the average pore diameter of the support and the intermediate layer) can be as low as about 6.0 μm.

[0122] The compressive and flexural strengths of the support were tested, and the test results are as follows: Figure 6 As shown. In the first slurry used to prepare the support to be tested, the mass ratio of alumina fiber to aluminum silicate fiber was 10:0 (i.e., without aluminum silicate fiber), 9.5:0.5, 9.0:1.0, 8.5:1.5, and 8.0:2.0, respectively. Other preparation parameters of the support were the same as in Example 2, including the calcination temperature of the first slurry, which was 1350°C.

[0123] from Figure 6 It can be seen that the mechanical properties of the support can be controlled by adjusting the ratio of alumina fiber and aluminum silicate fiber in the first slurry.

[0124] The surface porosity and pore size of the support were tested, and the test results are as follows: Figure 7 As shown. The calcination temperatures used in the preparation of the support to be tested were 1250℃, 1300℃, 1350℃, 1400℃, and 1450℃, respectively. Other preparation parameters of the support and intermediate layer were the same as in Example 2, including the mass ratio of alumina fiber to aluminum silicate fiber in the first slurry being 8.5:1.5.

[0125] from Figure 7 It can be seen that the porosity and pore size of the support can be adjusted by changing the calcination temperature of the first slurry. When the calcination temperature is 1350℃, the surface porosity of the support can reach 66.4%, and the average pore size is as low as 2.2μm.

[0126] The dust removal efficiency of the ceramic filter tube as a whole (including the surface coating layer) was tested under the following conditions: 300 mg / m³. 3 Dust, filtration velocity 0.8-1.2 m / min. Test results are as follows. Figure 8 As shown. The preparation method of the ceramic filter tube to be tested is similar to that of Example 2, except that the mass ratio of alumina fiber to aluminum silicate fiber in the first slurry used to prepare the ceramic filter tube to be tested is 10:0 (i.e., it does not contain aluminum silicate fiber). The other preparation parameters of the support, intermediate layer and surface coating layer are the same as those in Example 2.

[0127] from Figure 8 As can be seen, the ceramic filter tube provided by the present invention can achieve a maximum dust removal rate of 99.5%, demonstrating excellent dust removal capabilities.

[0128] The mechanical properties of the ceramic filter tube as a whole (including the surface coating layer) were tested, and the test results are as follows: Figure 9 As shown. The preparation method of the ceramic filter tube to be tested is similar to that of Example 2, except that the ratio of alumina fiber to aluminosilicate fiber in the first slurry is 10:0, and the calcination temperatures of the first slurry are 1250℃, 1300℃, 1350℃, 1400℃, and 1450℃, respectively. Other preparation parameters of the support, intermediate layer and surface coating layer are the same as those in Example 2.

[0129] from Figure 9 It can be seen that when the calcination temperature is 1400℃, the ceramic filter tube prepared by the present invention can reach a maximum compressive strength of 243MPa and a maximum compressive strength of 3.4GPa-3.5GPa, indicating that the ceramic filter tube provided by the present invention has high mechanical strength.

Claims

1. A method for preparing a ceramic filter tube, the method comprising: S1. Mix alumina fiber and aluminosilicate fiber at a mass ratio of 10:0-5:5, then add coagulant to form fiber slurry, then add dispersant, stir, and adjust the pH value to 8-10 to obtain the first slurry; Aluminum nitrate solution is mixed with aluminum powder and heated to obtain aluminum sol; The aluminum sol is filtered, then boehmite and spinning aid are added, and the mixture is concentrated to obtain a second slurry; the average particle size of the aluminum powder is less than or equal to 5 μm, the mass concentration of the aluminum nitrate solution is 5 g / 100 g - 35 g / 100 g; the mass of the aluminum powder is 10% - 25% of the mass of the aluminum nitrate solution; the heating temperature for preparing the aluminum sol is 82-98℃, and the heating time is 7-10 h; A first nano-alumina, polyethersulfone, isopropanol, N-methylpyrrolidone and glycerol are mixed in a ratio of 40-60:5-10:0.5-2:30-50:0.15-0.3 to obtain an intermediate slurry. Then, a second nano-alumina is added, with the mass of the second nano-alumina being 15%-25% of the mass of the intermediate slurry, to obtain a third slurry. S2. Using the filter tube mold as a mold, the first slurry is injected into the annulus between the inner and outer tubes of the filter tube mold, and the mixture is drawn and shaped. The first slurry in the filter tube mold is dried to obtain a blank. The blank is taken out from the filter tube mold and calcined to obtain a support. S3. Using the support obtained in S2 as a spinning roller, the second slurry is spun on the surface of the support at a spraying speed of 5L / min-20L / min, dried, and calcined to form an intermediate layer covering the outer surface of the support. S4. Encapsulate the inner side of the support obtained in S3, immerse the encapsulated support in the third slurry, remove the immersed support, dry it, and calcine it to obtain the ceramic filter tube. The filter tube mold includes an inner tube and an outer tube, the inner tube being a hollow tube, and the outer tube having two or more outwardly protrusions on its outer wall, the protrusions being hollow; there is an annular space between the inner tube and the outer tube for injecting slurry; the bottom of the filter tube mold has a bottom plate, and the top of the filter tube mold has a top plate, the top plate and the bottom plate respectively covering the top opening and bottom opening of the outer tube; The ceramic filter tube includes a support body, an intermediate layer, and a surface coating layer. The support body is a hollow tube structure. The outer tube wall of the support body has two or more outward protrusions. The top of the support body has an annular flange face that covers the top section of the tube wall of the support body. The intermediate layer covers the surface of the outer tube wall of the support; the surface coating layer covers the surface of the intermediate layer.

2. The production method according to claim 1, wherein, In S1, during the preparation of the first slurry, the lengths of the alumina fibers and aluminum silicate fibers are 2μm-10μm; The coagulant includes one or more of water glass, silica sol, aluminum sol, and aluminum phosphate. The mass of the dispersant is 0.1%-0.5% of the mass of the fiber slurry.

3. The preparation method according to claim 1, wherein, In S1, during the preparation of the second slurry, the average particle size of the boehmite is less than or equal to 2 μm; The mass of the boehmite is 0.5%-3% of the mass of the alumina sol; The mass of the spinning aid is 5%-12% of the mass of the aluminum sol; The spinning aid includes polyvinylpyrrolidone; the viscosity of the second slurry is 200 Pa s-550 Pa s.

4. The production method according to claim 1, wherein In S1, during the preparation of the third slurry, the average particle size of the first nano-alumina and the second nano-alumina is less than or equal to 30 nm.

5. The preparation method according to claim 1, wherein, In S2, the calcination temperature is 1000℃-1450℃, and the calcination time is 5min-60min.

6. The production method according to claim 1, wherein In S3, the linear speed of the spinning roller receiving the yarn is 100m / min-150m / min; In S3, the calcination process includes: raising the temperature to 250℃-400℃ at a rate of 2-4℃ / min, holding for 1h-3h, then raising the temperature to 650℃-900℃ at a rate of 2-4℃ / min, holding for 1h-3h, and finally raising the temperature to 1000℃-1450℃ at a rate of 3-5℃ / min, holding for 3min-30min to complete the calcination.

7. The production method according to claim 1, wherein In S4, the immersion time is 3-5 minutes; In S4, the heating rate of calcination is 3-5℃ / min, the calcination temperature is 1200℃-1350℃, and the calcination time is 5min-10min.

8. In the preparation method according to claim 1, the diameter of the top plate in the filter tube mold is 100mm-300mm; The ratio of the diameter of the inner tube to the diameter of the top plate is 0.5-0.8:1; At the same horizontal height, let m be the distance between the apex of the protrusion and the center of the inner tube cross-section, let n be the radius of the inner tube, and let m be (n+5mm) to (n+50mm). The vertical width of each protrusion of the outer tube is 20mm-50mm.

9. A ceramic filter tube, which is obtained by the method for preparing the ceramic filter tube according to any one of claims 1-8.

10. The ceramic filter tube of claim 9 wherein, The thickness of the intermediate layer is 10mm-40mm, and the thickness of the surface coating layer is 50μm-200μm.

11. The ceramic filter tube of claim 9 wherein, In the support body, the outer diameter of the flange face is 100mm-300mm; The ratio of the inner diameter of the support body to the outer diameter of the flange face is 0.5-0.8:1; At the same horizontal level, the distance from the apex of the protrusion to the center of the cross-section of the support is 5mm-50mm larger than the inner diameter of the support. The vertical width of each protrusion is 20mm-50mm.

12. The ceramic filter tube according to any one of claims 9-11, wherein, The porosity of the support is 50%-70%, and the pore size of the support is 2-3 μm; The compressive strength of the support is 0.5 GPa - 3 GPa, and the flexural strength of the support is 95 MPa - 130 MPa. The average porosity of the intermediate layer and the support is 30%-50%, and the average pore size of the intermediate layer and the support is 5-15μm. The ceramic filter tube has a compressive strength of 2.5 GPa - 3.5 GPa and a flexural strength of 195 MPa - 250 MPa.

13. A ceramic filter tube integrating dust removal and denitrification, comprising the ceramic filter tube according to any one of claims 9-12.

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