High-strength large-filtration-area ceramic membrane tube and preparation method thereof

Abstract

The application discloses a high-strength large-filtration-area ceramic membrane tube and a preparation method thereof, and relates to the technical field of ceramic membrane tubes. The installation expansion end, the reinforced neck part, the petal-shaped tube body and the sealing tube bottom are integrally sintered from top to bottom, the wall thickness of the reinforced neck part is greater than that of the petal-shaped tube body, the sealing tube bottom seals the bottom end of the petal-shaped tube body, and the sealing tube bottom is of a solid structure. The cross section of the petal-shaped tube body is petal-shaped, and the petal-shaped tube body comprises a plurality of petal-shaped protrusions, and the outer side of the petal-shaped protrusions is an outward convex circular arc filtering surface. Compared with conventional straight cylinder type ceramic membrane tubes, the filtration area can be increased by 1.5-2 times, the loading area of the ceramic membrane equipment is increased, the land occupation area of the ceramic membrane dust removal equipment is reduced, the longitudinal reinforcing ribs and the transverse reinforcing rings arranged on the tube body are evenly distributed on the ceramic membrane tube to bear stress and enhance the strength of the ceramic membrane tube.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection new materials technology, and particularly relates to a high-strength ceramic membrane tube with a large filtration area and its preparation method. Background Technology

[0002] High-efficiency separation technologies based on new materials are applied across various fields, including energy conservation and emission reduction, clean energy, environmental governance, circular economy, and low-carbon economy. High-temperature gas from coal-fired power generation and coal liquefaction in the energy industry, high-temperature silane mixtures in the photovoltaic industry, high-temperature reaction gases in the petrochemical and chemical industries, high-temperature gas from blast furnaces and converters in the metallurgical industry, high-temperature tail gas in the glass industry, and high-temperature waste gas from boilers and incinerators all require direct purification and dust removal of solid-containing gases at high temperatures. Among various high-temperature gas purification and dust removal technologies, ceramic membrane filtration technology has significant advantages. It achieves gas-solid separation through a ceramic membrane medium, purifying the gas and recovering resources. It not only maximizes the utilization of the sensible heat of the gas, improving energy efficiency, but also simplifies the process, saves investment in process equipment, conserves water resources, and avoids secondary water pollution caused by wet dust removal.

[0003] Currently used ceramic membranes are mostly tubular membranes, which are sealed at one end and open at the other, suspended on a tube sheet. The tube body is cylindrical, and the small filtration area of ​​a single ceramic membrane tube results in large footprint and high cost for ceramic membrane dust removal equipment, limiting its application. Furthermore, frequent backflushing during operation can cause vibration in the dust removal equipment, leading to breakage of the ceramic membrane tube's installation neck and affecting normal operation. After a period of use, the overall strength of the ceramic membrane tube decreases due to high temperature, high pressure, and corrosive media, causing collapse-type fractures, severely impacting the lifespan of the ceramic membrane and the stability of the high-temperature dust removal process. Summary of the Invention

[0004] To address the issues of small filtration area and low strength of individual ceramic membranes, this invention discloses a high-strength, large-filtration-area ceramic membrane tube and its preparation method. Compared with conventional straight-tube ceramic membrane tubes, its petal-shaped ceramic tube structure can increase the filtration area by 1.5-2 times, increasing the filling area of ​​the ceramic membrane equipment and reducing the floor space occupied by the ceramic membrane dust removal equipment. The longitudinal reinforcing ribs and transverse reinforcing rings set in the tube body can evenly distribute the stress on the ceramic membrane tube and enhance its strength.

[0005] The technical solution of this invention: A high-strength ceramic membrane tube with a large filtration area includes an expansion end, a reinforcing neck, a petal-shaped tube body, and a sealed tube bottom. The expansion end, reinforcing neck, petal-shaped tube body, and sealed tube bottom are integrally sintered from top to bottom. The wall thickness of the reinforcing neck is greater than the wall thickness of the petal-shaped tube body. The sealed tube bottom closes the bottom end of the petal-shaped tube body and is a solid sealing structure. The cross-section of the petal-shaped tube body is petal-shaped and includes multiple petal-shaped protrusions. The outer side of the petal-shaped protrusions is an outwardly convex arc filter surface. A longitudinal reinforcing rib is provided at the concave connection between two adjacent petal-shaped protrusions. The petal-shaped tube body is designed with a transverse reinforcing ring, the outer diameter of which is the same as the outer tangent circle diameter of the petal-shaped protrusion.

[0006] Furthermore, the number of petal-shaped protrusions is 6 to 12, the radius of curvature of the outward convex arc of the petal-shaped protrusion is 8 to 15 mm, the included angle between the central axes of two adjacent petal-shaped protrusions is 30 to 60°, the radius of curvature of the concave arc at the concave connection between adjacent petal-shaped protrusions is 3 to 6 mm, and the entire circumference arc surface is smooth, continuous and without inflection points.

[0007] Furthermore, the petal-shaped tube body has a double-layer composite gradient pore structure, with an outer layer being a filter membrane layer and an inner layer being a support layer. The pore size of the filter membrane layer is 0.05-5μm and the porosity is 65-70%, while the pore size of the support layer is 5-20μm and the porosity is 50-80%.

[0008] Furthermore, the longitudinal reinforcing rib is a solid structure made of metal or ceramic, with a diameter of 1-3mm. Its top is located inside the reinforcing neck, its middle part passes through the transverse reinforcing ring, and its bottom is located inside the bottom of the sealing tube.

[0009] Furthermore, the transverse reinforcing rings are made of one of alumina, zirconium oxide, or silicon carbide, and there are 1-5 of them, with a length of 1-3 cm, and they are evenly distributed longitudinally on the petal-shaped tube.

[0010] Furthermore, the bottom length of the sealing tube is 3-8cm, the outer diameter is the same as the outer tangent circle diameter of the petal-shaped protrusion, and a positioning hole is opened at the bottom of the sealing tube.

[0011] Furthermore, the length of the reinforcing neck is 3-5cm, and the outer diameter of the reinforcing neck is the same as the diameter of the outer tangent circle of the petal-shaped protrusion.

[0012] A method for preparing a high-strength, large-area ceramic membrane tube includes the following steps: Step 1: Raw material preparation and mixing. According to the mass proportions, the ceramic matrix powder, binder, lubricant and pore-forming agent are mixed in proportion. The mixture is thoroughly stirred in a three-dimensional mixer, sealed and kept at a constant temperature for 24~36 hours to prepare ceramic clay. Step 2: Pre-embedded reinforcing ribs and isostatic pressing. A special isostatic pressing mold adapted to the petal contour and a stainless steel rod are used. The longitudinal reinforcing ribs and stainless steel rods are pre-positioned inside the mold. Then, the ceramic clay prepared in Step 1 is filled into the mold. After filling, it is placed into the isostatic pressing equipment for integral molding to obtain the blank. The inner diameter of the isostatic pressing mold at the reinforcing neck and the transverse reinforcing ring is the same as the outer diameter of the petal contour. Step 3: Drying the preform and sintering the support. The preform is placed in a ventilated drying oven for low-temperature ventilation drying, and then placed in a kiln for sintering to obtain a ceramic membrane tube support. Step 4: Coating and secondary sintering. The film-forming liquid is sprayed onto the outside of the ceramic tube support prepared in step 3 using a spraying process. After drying, it is placed in a kiln for programmed heating and secondary sintering. After programmed cooling, a high-strength ceramic membrane tube with a large filtration area is obtained.

[0013] Furthermore, in step one, the ceramic matrix powder is one or more of silicon carbide, alumina, and zirconium oxide; the binder is paraffin oil; the lubricant is polyvinyl alcohol; and the pore-forming agent is carbon powder. The mass percentages of each component are as follows: ceramic matrix powder 65-80%, binder 5-10%, lubricant 3-8%, and pore-forming agent 5-10%. In step two, the isostatic pressing pressure is 140-190 MPa, and the pressure is maintained for 1-2 hours after isostatic pressing. In step three, the kiln sintering temperature is 500-800℃, and the sintering time is 0.5-2 hours.

[0014] Furthermore, in step four, the temperature is first programmed to rise to 500-800℃ and held in air for 1-2 hours. Then, nitrogen gas is introduced, and the temperature is raised to 1400-1700℃ in nitrogen atmosphere and held for 2-4 hours. Then, the temperature is programmed to drop to 300-500℃ and finally cooled naturally to room temperature. The programmed heating and cooling rates are both 5-15℃ / min.

[0015] The beneficial effects of this invention are: (1) Large filtration area and small equipment space: The petal-shaped tube body is used to replace the traditional straight cylinder structure. The filtration area is increased by 1.5-2 times under the same external size, the single tube filtration flux is greatly improved, the membrane tube filling capacity can be increased, the dust removal and filtration equipment footprint is effectively reduced, and the overall equipment installation cost is reduced.

[0016] (2) The bidirectional reinforcement structure provides high overall strength to the tube. Combined with longitudinal reinforcing ribs and transverse reinforcing rings, it forms a three-dimensional reinforcement structure that evenly distributes the compressive and bending stresses of the tube, compensating for the high brittleness of ceramic materials. Simultaneously, a thickened reinforcing neck is provided to accommodate on-site installation and sealing stress, preventing pipe opening cracks and significantly improving the membrane tube's compressive strength, bending resistance, and service life. The molding process is stable, resulting in high product consistency: The pre-embedded reinforcing ribs and isostatic pressing integrated molding process, combined with a segmented temperature-controlled secondary sintering process, ensures uniform body density, defect-free structure, precise positioning of longitudinal reinforcing ribs, and good consistency in the finished product's mechanical and filtration performance, facilitating large-scale mass production. Attached Figure Description

[0017] Figure 1 This is a diagram showing the external shape of the ceramic membrane tube described in this invention.

[0018] Figure 2 This is a schematic diagram of the cross-section of the petal-shaped tube body described in this invention.

[0019] Figure 3 This is a comparison chart of the air permeability of the ceramic membrane tube described in Embodiment 1 of the present invention and that of a regular membrane tube.

[0020] Wherein: 1-Installation end, 2-Reinforced neck, 3-Petal-shaped tube body, 4-Sealed tube bottom, 301-Petal-shaped protrusion, 302-Filter membrane layer, 303-Support layer, 304-Longitudinal reinforcing rib, 305-Transverse reinforcing ring, 401-Positioning hole. Detailed Implementation Example 1

[0021] A high-strength ceramic membrane tube with a large filtration area includes an expansion end 1, a reinforcing neck 2, a petal-shaped tube body 3, and a sealing tube bottom 4. The expansion end 1, the reinforcing neck 2, the petal-shaped tube body 3, and the sealing tube bottom 4 are integrally sintered from top to bottom. The wall thickness of the reinforcing neck 2 is greater than the wall thickness of the petal-shaped tube body 3. The sealing tube bottom 4 seals the bottom end of the petal-shaped tube body 3, and the sealing tube bottom is a solid sealing structure. The cross-section of the petal-shaped tube body 3 is petal-shaped, including multiple petal-shaped protrusions 301. The outer side of the petal-shaped protrusions 301 is an outwardly convex arc filter surface. A longitudinal reinforcing rib 304 is provided at the concave connection between two adjacent petal-shaped protrusions 301. The petal-shaped tube body 3 is designed with a transverse reinforcing ring 305, and the outer diameter of the transverse reinforcing ring 305 is the same as the diameter of the outer tangent circle of the petal-shaped protrusions 301.

[0022] Furthermore, the number of petal-shaped protrusions 301 is 6, the radius of curvature of the outward convex arc of the petal-shaped protrusions 301 is 15mm, the included angle between the central axes of two adjacent petal-shaped protrusions 301 is 30°, the radius of curvature of the concave arc at the concave connection between adjacent petal-shaped protrusions 301 is 6mm, and the entire circumference arc surface is smooth and continuous without inflection points.

[0023] Furthermore, the petal-shaped tube body 3 has a double-layer composite gradient pore structure, with an outer layer of filter membrane 302 and an inner layer of support layer 303. The filter membrane 302 has a pore size of 0.05 μm and a porosity of 65%, while the support layer 303 has a pore size of 5 μm and a porosity of 50%.

[0024] Furthermore, the longitudinal reinforcing rib 304 is made of solid metal or ceramic, with a diameter of 1-mm. Its top is located inside the reinforcing neck 2, its middle part passes through the transverse reinforcing ring 305, and its bottom is located inside the bottom of the sealing tube 4.

[0025] Furthermore, the transverse reinforcing 305 ring is made of aluminum oxide, there is one ring, the length is 3cm, and it is evenly distributed longitudinally on the petal-shaped tube body 3.

[0026] Furthermore, the sealing tube bottom 4 is 3cm long, and its outer diameter is the same as the outer diameter of the petal-shaped protrusion 301. A positioning hole 401 is opened at the bottom of the sealing tube bottom 4.

[0027] Furthermore, the length of the reinforcing neck 2 is 3cm, and the outer diameter of the reinforcing neck 2 is the same as the diameter of the circumscribed circle of the petal-shaped protrusion 301.

[0028] A method for preparing a high-strength, large-area ceramic membrane tube includes the following steps: Step 1: Raw material preparation and mixing. According to the mass proportions, the ceramic matrix powder, binder, lubricant and pore-forming agent are mixed in proportion, thoroughly stirred in a three-dimensional mixer, sealed and kept at a constant temperature for 24 hours to prepare ceramic clay. Step 2: Pre-embedded reinforcing ribs and isostatic pressing. A special isostatic pressing mold adapted to the petal contour and a stainless steel rod are used. The longitudinal reinforcing ribs 304 and stainless steel rods are pre-positioned inside the mold. Then, the ceramic clay prepared in Step 1 is filled into the mold. After filling, it is placed into the isostatic pressing equipment for integral molding to obtain the blank. The inner diameter of the isostatic pressing mold at the reinforcing neck 2 and the transverse reinforcing ring 305 is the same as the outer tangent circle diameter at the petal contour. Step 3: Drying the preform and sintering the support. The preform is placed in a ventilated drying oven for low-temperature ventilation drying, and then placed in a kiln for sintering to obtain a ceramic membrane tube support. Step 4: Coating and secondary sintering. The film-forming liquid is sprayed onto the outside of the ceramic tube support prepared in step 3 using a spraying process. After drying, it is placed in a kiln for programmed heating and secondary sintering. After programmed cooling, a high-strength ceramic membrane tube with a large filtration area is obtained.

[0029] Furthermore, in step one, the ceramic matrix powder is alumina, the binder is paraffin oil, the lubricant is polyvinyl alcohol, and the pore-forming agent is carbon powder. The mass percentages of each component are: ceramic matrix powder 65%, binder 5%, lubricant 3%, and pore-forming agent 5%. In step two, the isostatic pressing pressure is 140 MPa, and the pressure is maintained for 1 hour after isostatic pressing. In step three, the kiln sintering temperature is 500℃, and the sintering time is 2 hours.

[0030] Furthermore, in step four, the temperature is first programmed to rise to 500°C and held at that temperature for 1 hour in an air atmosphere. Then, nitrogen gas is introduced, and the temperature is raised to 1400°C in a nitrogen atmosphere and held for 2 hours. Then, the temperature is programmed to drop to 300°C and finally cooled naturally to room temperature. The programmed heating and cooling rates are both 5°C / min.

[0031] The high-strength, large-filtration-area ceramic membrane tube prepared in this embodiment has a filtration area that is 1.5 times that of a conventional cylindrical ceramic membrane tube of the same size, and its strength is increased by 2 times compared with that of a conventional ceramic membrane tube. Its filtration efficiency for 0.3μm particles is greater than 99.99%. Example 2

[0032] A high-strength ceramic membrane tube with a large filtration area includes an expansion end 1, a reinforcing neck 2, a petal-shaped tube body 3, and a sealing tube bottom 4. The expansion end 1, the reinforcing neck 2, the petal-shaped tube body 3, and the sealing tube bottom 4 are integrally sintered from top to bottom. The wall thickness of the reinforcing neck 2 is greater than the wall thickness of the petal-shaped tube body 3. The sealing tube bottom 4 seals the bottom end of the petal-shaped tube body 3, and the sealing tube bottom is a solid sealing structure. The cross-section of the petal-shaped tube body 3 is petal-shaped, including multiple petal-shaped protrusions 301. The outer side of the petal-shaped protrusions 301 is an outwardly convex arc filter surface. A longitudinal reinforcing rib 304 is provided at the concave connection between two adjacent petal-shaped protrusions 301. The petal-shaped tube body 3 is designed with a transverse reinforcing ring 305, and the outer diameter of the transverse reinforcing ring 305 is the same as the diameter of the outer tangent circle of the petal-shaped protrusions 301.

[0033] Furthermore, the number of petal-shaped protrusions 301 is 12, the radius of curvature of the outward convex arc of the petal-shaped protrusions 301 is 8mm, the included angle between the central axes of two adjacent petal-shaped protrusions 301 is 60°, the radius of curvature of the concave arc at the concave connection between adjacent petal-shaped protrusions 301 is 6mm, and the entire circumference arc surface is smooth and continuous without inflection points.

[0034] Furthermore, the petal-shaped tube body 3 has a double-layer composite gradient pore structure, with an outer layer of filter membrane 302 and an inner layer of support layer 303. The filter membrane 302 has a pore size of 5μm and a porosity of 70%, while the support layer 303 has a pore size of 20μm and a porosity of 80%.

[0035] Furthermore, the longitudinal reinforcing rib 304 is made of solid metal or ceramic, with a diameter of 1-3mm. Its top is located inside the reinforcing neck 2, its middle part passes through the transverse reinforcing ring 305, and its bottom is located inside the bottom of the sealing tube 4.

[0036] Furthermore, the transverse reinforcing rings are made of zirconium oxide, numbered in the form of 5 rings, each 1 cm in length, and are evenly distributed longitudinally on the petal-shaped tube body 3.

[0037] Furthermore, the sealing tube bottom 4 is 8cm long, and its outer diameter is the same as the outer diameter of the petal-shaped protrusion 301. A positioning hole 401 is opened at the bottom of the sealing tube bottom 4.

[0038] Furthermore, the length of the reinforcing neck 2 is 5cm, and the outer diameter of the reinforcing neck 2 is the same as the diameter of the circumscribed circle of the petal-shaped protrusion 301.

[0039] A method for preparing a high-strength, large-area ceramic membrane tube includes the following steps: Step 1: Raw material preparation and mixing. According to the mass proportions, the ceramic matrix powder, binder, lubricant and pore-forming agent are mixed in proportion. The mixture is thoroughly stirred in a three-dimensional mixer, sealed and kept at a constant temperature for 36 hours to prepare ceramic clay. Step 2: Pre-embedded reinforcing ribs and isostatic pressing. A special isostatic pressing mold adapted to the petal contour and a stainless steel rod are used. The longitudinal reinforcing ribs 304 and stainless steel rods are pre-positioned inside the mold. Then, the ceramic clay prepared in Step 1 is filled into the mold. After filling, it is placed into the isostatic pressing equipment for integral molding to obtain the blank. The inner diameter of the isostatic pressing mold at the reinforcing neck 2 and the transverse reinforcing ring 305 is the same as the outer tangent circle diameter at the petal contour. Step 3: Drying the preform and sintering the support. The preform is placed in a ventilated drying oven for low-temperature ventilation drying, and then placed in a kiln for sintering to obtain a ceramic membrane tube support. Step 4: Coating and secondary sintering. The film-forming liquid is sprayed onto the outside of the ceramic tube support prepared in step 3 using a spraying process. After drying, it is placed in a kiln for programmed heating and secondary sintering. After programmed cooling, a high-strength ceramic membrane tube with a large filtration area is obtained.

[0040] Furthermore, in step one, the ceramic matrix powder is silicon carbide, the binder is paraffin oil, the lubricant is polyvinyl alcohol, and the pore-forming agent is carbon powder. The mass percentages of each component are as follows: ceramic matrix powder 80%, binder 10%, lubricant 8%, and pore-forming agent 10%. In step two, the isostatic pressing pressure is 190 MPa, and the pressure is maintained for 2 hours after isostatic pressing. In step three, the kiln sintering temperature is 800℃, and the sintering time is 0.5 hours.

[0041] Furthermore, in step four, the temperature is first programmed to rise to 800°C and held at that temperature for 2 hours in an air atmosphere. Then, nitrogen gas is introduced, and the temperature is raised to 1700°C in a nitrogen atmosphere and held for 4 hours. Then, the temperature is programmed to drop to 500°C and finally cooled naturally to room temperature. The programmed heating and cooling rates are both 15°C / min.

[0042] The high-strength, large-filtration-area ceramic membrane tube prepared in this embodiment has a filtration area twice that of a conventional straight-tube ceramic membrane tube of the same size, and its strength is 1.8 times greater than that of a conventional ceramic membrane tube. Its filtration efficiency for 0.3μm particles is greater than 99.995%. Example 3

[0043] A high-strength ceramic membrane tube with a large filtration area includes an expansion end 1, a reinforcing neck 2, a petal-shaped tube body 3, and a sealing tube bottom 4. The expansion end 1, the reinforcing neck 2, the petal-shaped tube body 3, and the sealing tube bottom 4 are integrally sintered from top to bottom. The wall thickness of the reinforcing neck 2 is greater than the wall thickness of the petal-shaped tube body 3. The sealing tube bottom 4 seals the bottom end of the petal-shaped tube body 3, and the sealing tube bottom is a solid sealing structure. The cross-section of the petal-shaped tube body 3 is petal-shaped, including multiple petal-shaped protrusions 301. The outer side of the petal-shaped protrusions 301 is an outwardly convex arc filter surface. A longitudinal reinforcing rib 304 is provided at the concave connection between two adjacent petal-shaped protrusions 301. The petal-shaped tube body 3 is designed with a transverse reinforcing ring 305, and the outer diameter of the transverse reinforcing ring 305 is the same as the diameter of the outer tangent circle of the petal-shaped protrusions 301.

[0044] Furthermore, the number of petal-shaped protrusions 301 is 10, the radius of curvature of the outward convex arc of the petal-shaped protrusions 301 is 12mm, the angle between the central axes of two adjacent petal-shaped protrusions 301 is 40°, the radius of curvature of the concave arc at the concave connection between adjacent petal-shaped protrusions 301 is 4mm, and the entire circumference arc surface is smooth and continuous without inflection points.

[0045] Furthermore, the petal-shaped tube body 3 has a double-layer composite gradient pore structure, with an outer layer of filter membrane 302 and an inner layer of support layer 303. The filter membrane 302 has a pore size of 1μm and a porosity of 68%, while the support layer 303 has a pore size of 10μm and a porosity of 60%.

[0046] Furthermore, the longitudinal reinforcing rib 304 is made of solid metal or ceramic, with a diameter of 1-3mm. Its top is located inside the reinforcing neck 2, its middle part passes through the transverse reinforcing ring 305, and its bottom is located inside the bottom of the sealing tube 4.

[0047] Furthermore, the transverse reinforcing rings 305 are made of silicon carbide, there are 3 of them, each 2cm in length, and they are evenly distributed longitudinally on the petal-shaped tube body 3.

[0048] Furthermore, the sealing tube bottom 4 is 5cm long, and its outer diameter is the same as the outer diameter of the petal-shaped protrusion 301. A positioning hole 401 is opened at the bottom of the sealing tube bottom 4.

[0049] Furthermore, the length of the reinforcing neck 2 is 4cm, and the outer diameter of the reinforcing neck 2 is the same as the diameter of the circumscribed circle of the petal-shaped protrusion 301.

[0050] A method for preparing a high-strength, large-area ceramic membrane tube includes the following steps: Step 1: Raw material preparation and mixing. According to the mass proportions, the ceramic matrix powder, binder, lubricant and pore-forming agent are mixed in proportion. The mixture is thoroughly stirred in a three-dimensional mixer, sealed and kept at a constant temperature for 30 hours to prepare ceramic clay. Step 2: Pre-embedded reinforcing ribs and isostatic pressing. A special isostatic pressing mold adapted to the petal contour and a stainless steel rod are used. The longitudinal reinforcing ribs 304 and stainless steel rods are pre-positioned inside the mold. Then, the ceramic clay prepared in Step 1 is filled into the mold. After filling, it is placed into the isostatic pressing equipment for integral molding to obtain the blank. The inner diameter of the isostatic pressing mold at the reinforcing neck 2 and the transverse reinforcing ring 305 is the same as the outer tangent circle diameter at the petal contour. Step 3: Drying the preform and sintering the support. The preform is placed in a ventilated drying oven for low-temperature ventilation drying, and then placed in a kiln for sintering to obtain a ceramic membrane tube support. Step 4: Coating and secondary sintering. The film-forming liquid is sprayed onto the outside of the ceramic tube support prepared in step 3 using a spraying process. After drying, it is placed in a kiln for programmed heating and secondary sintering. After programmed cooling, a high-strength ceramic membrane tube with a large filtration area is obtained.

[0051] Furthermore, in step one, the ceramic matrix powder is silicon carbide and zirconium oxide, the binder is paraffin oil, the lubricant is polyvinyl alcohol, and the pore-forming agent is carbon powder. The mass percentages of each component are as follows: ceramic matrix powder 70%, binder 8%, lubricant 6%, and pore-forming agent 8%. In step two, the isostatic pressing pressure is 150 MPa, and the pressure is maintained for 1.5 hours after isostatic pressing. In step three, the kiln sintering temperature is 600℃, and the sintering time is 1 hour.

[0052] Furthermore, in step four, the temperature is first programmed to rise to 700°C and held at that temperature for 1.5 hours in an air atmosphere. Then, nitrogen gas is introduced, and the temperature is raised to 1600°C in a nitrogen atmosphere and held for 3 hours. Then, the temperature is programmed to drop to 400°C and finally cooled naturally to room temperature. The programmed heating and cooling rates are both 10°C / min.

[0053] The high-strength, large-filtration-area ceramic membrane tube prepared in this embodiment has a filtration area 1.6 times that of a conventional cylindrical ceramic membrane tube of the same size, and its strength is 2.5 times greater than that of a conventional ceramic membrane tube. Its filtration efficiency for 0.3μm particles is greater than 99.995%.

Claims

1. A high-strength ceramic membrane tube with a large filtration area, characterized in that, The device includes an expansion end (1), a reinforcing neck (2), a petal-shaped tube body (3), and a sealing tube bottom (4). The expansion end (1), the reinforcing neck (2), the petal-shaped tube body (3), and the sealing tube bottom (4) are integrally sintered from top to bottom. The wall thickness of the reinforcing neck (2) is greater than the wall thickness of the petal-shaped tube body (3), and the sealing tube bottom (4) closes the bottom end of the petal-shaped tube body (3). The sealing tube bottom (4) is a solid structure. The cross-section of the petal-shaped tube body (3) is petal-shaped, including multiple petal-shaped protrusions (301). The outer side of the petal-shaped protrusions (301) is an outwardly convex arc filter surface. A longitudinal reinforcing rib (304) is provided at the concave connection between two adjacent petal-shaped protrusions (301). The petal-shaped tube body (3) is designed with a transverse reinforcing ring (305). The outer diameter of the transverse reinforcing ring (305) is the same as the outer diameter of the petal-shaped protrusion (301).

2. The high-strength, large-area ceramic membrane tube according to claim 1, characterized in that, The number of petal-shaped protrusions (301) is 6 to 12. The radius of curvature of the outward convex arc of the petal-shaped protrusion (301) is 8-15 mm. The included angle between the central axes of two adjacent petal-shaped protrusions (301) is 30-60°. The radius of curvature of the concave arc at the concave connection between adjacent petal-shaped protrusions (301) is 3-6 mm. The entire circumference arc surface is smooth, continuous and without inflection points.

3. The high-strength, large-filtration-area ceramic membrane tube according to claim 1, characterized in that, The petal-shaped tube body (3) is a double-layer composite gradient pore structure. The outer layer is a filter membrane layer (302) and the inner layer is a support layer (303). The pore size of the filter membrane layer (302) is 0.05-5μm and the porosity is 65-70%. The pore size of the support layer (303) is 5-20μm and the porosity is 50-80%.

4. The high-strength, large-area ceramic membrane tube according to claim 1, characterized in that, The longitudinal reinforcing rib (304) is a solid structure made of metal or ceramic, with a diameter of 1-3 mm. Its top is located inside the reinforcing neck (2), its middle part passes through the transverse reinforcing ring (305), and its bottom is located inside the bottom of the sealing tube (4).

5. A high-strength, large-filtration-area ceramic membrane tube according to claim 1, characterized in that, The transverse reinforcing ring (305) is made of one of aluminum oxide, zirconium oxide, or silicon carbide, and there are 1-5 of them. The length is 1-3cm, and they are evenly distributed longitudinally on the petal-shaped tube body (3).

6. A high-strength, large-filtration-area ceramic membrane tube according to claim 1, characterized in that, The length of the sealing tube bottom (4) is 3-8cm, and its outer diameter is the same as the outer diameter of the petal-shaped protrusion (301). The bottom of the sealing tube bottom (4) has a positioning hole (401).

7. A high-strength, large-filtration-area ceramic membrane tube according to claim 1, characterized in that, The length of the reinforcing neck (2) is 3-5cm, and the outer diameter of the reinforcing neck (2) is the same as the outer diameter of the petal-shaped protrusion (301).

8. A method for preparing a high-strength, large-area ceramic membrane tube according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Raw material preparation and mixing. According to the mass proportions, the ceramic matrix powder, binder, lubricant and pore-forming agent are mixed in proportion. The mixture is thoroughly stirred in a three-dimensional mixer, sealed and kept at a constant temperature for 24~36 hours to prepare ceramic clay. Step 2: Pre-embedded reinforcing ribs and isostatic pressing. A special isostatic pressing mold adapted to the petal outline and a stainless steel rod are used. The longitudinal reinforcing ribs (304) and stainless steel rods are pre-positioned inside the mold. Then, the ceramic clay prepared in Step 1 is filled into the mold. After filling, it is placed into the isostatic pressing equipment for integral molding to obtain the blank. The inner diameter of the isostatic pressing mold at the reinforcing neck (2) and the transverse reinforcing ring (305) is the same as the outer tangent circle diameter at the petal outline. Step 3: Drying the preform and sintering the support. The preform is placed in a ventilated drying oven for low-temperature ventilation drying, and then placed in a kiln for sintering to obtain a ceramic membrane tube support. Step 4: Coating and secondary sintering. The film-forming liquid is sprayed onto the outside of the ceramic tube support prepared in step 3 using a spraying process. After drying, it is placed in a kiln for programmed heating and secondary sintering. After programmed cooling, a high-strength ceramic membrane tube with a large filtration area is obtained.

9. The method for preparing a high-strength, large-area ceramic membrane tube according to claim 8, characterized in that, In step one, the ceramic matrix powder is one or more of silicon carbide, alumina, and zirconium oxide; the binder is paraffin oil; the lubricant is polyvinyl alcohol; and the pore-forming agent is carbon powder. The mass percentages of each component are as follows: ceramic matrix powder 65-80%, binder 5-10%, lubricant 3-8%, and pore-forming agent 5-10%. In step two, the isostatic pressing pressure is 140-190 MPa, and the pressure is maintained for 1-2 hours after isostatic pressing. In step three, the kiln sintering temperature is 500-800℃, and the sintering time is 0.5-2 hours.

10. The method for preparing a high-strength, large-filtration-area ceramic membrane tube according to claim 8, characterized in that, In step four, the temperature is first programmed to rise to 500-800℃ and held in air for 1-2 hours. Then, nitrogen is introduced and the temperature is raised to 1400-1700℃ in nitrogen atmosphere and held for 2-4 hours. Then, the temperature is programmed to drop to 300-500℃ and finally cooled naturally to room temperature. The programmed heating and cooling rates are both 5-15℃ / min.

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