A high flux metal powder coated sintered mesh filter tube

Abstract

The application discloses a large-flux metal powder plated sintered mesh filter tube, which comprises a tubular multi-layer sintered mesh base material formed by rolling and welding and a metal film filter layer plated on the outer surface of the tubular multi-layer sintered mesh base material. The large-flux metal powder plated sintered mesh filter tube can effectively solve the problem that the precision, flow capacity and strength of the existing metal powder and metal wire mesh composite filter tube cannot be considered simultaneously in practical application, effectively solve the leakage and layer opening risk of the existing welded longitudinal seam filter tube, and effectively avoid the damage of the traditional film coating process to the metal film layer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal sintered mesh composite metal powder sintered filter tube, and particularly relates to a large-flux metal powder coating sintered mesh filter tube. BACKGROUND

[0002] The catalyst slurry filter is used for removing catalyst particles in residual oil after catalytic cracking of ACO light oil processing device. The ACO catalyst slurry is used as a blending component of fuel oil, and therefore, the impurity solid content in the catalyst slurry needs to be further removed. The filter device requires that the solid content at the outlet is less than 50 ppmw. The catalyst content in the catalyst slurry is as high as 12000-18000 ppmw, the working temperature is 200 DEG C, the slurry contains 10000 ppmw of resin and asphalt, and the online backwashing pressure is as high as 1.15 MPag. Therefore, in order to achieve the requirements of the filter device, the required filtering precision and efficiency are at least 1 mu m @ 95%, and the filter core needs to withstand the backwashing pressure of 1.15 MPag at a high temperature for a long period. Therefore, the filter core needs to have high precision, high flux, high strength at a high temperature, and the filter material structure design of the filter core is beneficial to backwashing and regeneration.

[0003] The ME101 filter of the S-Zorb device for desulfurization of catalytic gasoline in the petroleum refining process is a key device in the process, and the filter uses a metal sintered powder filter core. Currently, the filter core uses metal powder as a raw material, is formed through cold isostatic pressing, and is made through high-temperature vacuum sintering. By selecting the particle size of the metal powder and the process parameters, the pore size and distribution of the element can be adjusted. By using the pore structure, material composition, pressure resistance, and other characteristics of different filtering materials, a final filtering product suitable for the needs of users is developed. The backflushing pressure of the ME101 filter is as high as 3 MPa, the backflushing frequency is 20 times / min, the working temperature is 430 DEG C, the backflushing nitrogen temperature is 150 DEG C, and the temperature difference during work is as high as 280 DEG C. The high pressure, high frequency, and high temperature difference of backflushing will generate stress and torque on the filter core. Although the current technology has a metal powder and metal mesh composite asymmetric filter core, the longitudinal seam of the powder film layer is formed by argon arc welding. Since there is air in the sintered powder layer of the honeycomb structure, the argon gas cannot blow away the air during the welding process, and the welding protection effect is not good. Therefore, the film layer causes damage to the pore size of the filter core after welding, and stress concentration occurs at the welding seam, and the connection at the welding seam is prone to fracture under long-period high pressure and high temperature backflushing, thereby affecting the service life of the filter core.

[0004] With the compulsory control of environmental protection indexes of the state on petroleum chemical plants and the objective demand of increasing capacity of many devices, because of the size limitation of the original filter tank and the high cost of adding new devices, the upgrading of the existing filter core of the filter must be considered, and the selection of high-performance and large-flux filtering elements is the most efficient scheme at the present stage and is also the development trend of future refining enterprises.

[0005] The existing metal powder and metal sintered mesh composite filter element process technology in the market: rolling base material + spraying technology (see patents CN107983016A, CN204767841U, CN205516897U) is to sinter a sheet-shaped multi-layer sintered metal mesh first, spray a layer of fine powder with a particle size of 200-800 on the outer surface of the sheet-shaped sintered metal mesh, then roll it into a sheet-shaped material of a certain thickness through two tangent rollers, and then make a kind of metal powder and metal mesh composite sheet filter through vacuum sintering, and finally roll and weld the longitudinal seam to make a filter tube.

[0006] In this process, the base material generally uses a multi-layer metal sintered mesh to bear the strength of the entire filter material, and the sprayed layer serves as the filter layer. Since it is a sheet material and the base material is sprayed in a plane, the selection of the aperture is particularly important. If the aperture is too large, the flow capacity will increase, but the fine powder in the filter layer will fall into the support layer and block some pores. If the aperture is too small, the problem of the fine powder in the filter layer combining with the support layer is solved, but the strength will inevitably decrease (the aperture size of the woven mesh is proportional to the strength). Although the metal powder sintered plate can be selected as the base material because the aperture size of the powder material is inversely proportional to the strength, although the selection of the powder rolling plate as the filter layer fine powder will not cause the fine powder to block the base material, the selection of a too small aperture base material will reduce the flow capacity. This combination still sacrifices the flow capacity to ensure the strength and the feasibility of production. Even if we select a suitable base material to make a non-symmetrical sintered sheet material that basically meets the requirements, the subsequent filter element production is still a high-difficulty challenge. The rolling process of the filter material into a cylindrical shape will cause stretching damage to the original pore structure, and the heat generated by the longitudinal seam welding often causes cracks in the filter layer, which poses a fatal hidden danger to the filter precision. In the case of the same diameter of the filter element, the filter element with a weld usually has a smaller effective filtration area than the filter element without a weld. Although the influence of a single filter element is not large, for a device with hundreds of filter elements installed, the difference is like heaven and earth. Because of the existence of the weld, there is a blind area for backwashing, and there is also high pressure generated by backwashing. The weld cannot be unloaded in time, and the strength of the weld will also be damaged over time.

[0007] In summary, the metal powder and metal mesh composite filter element produced by the rolling base material + spraying technology cannot achieve high-precision filtration and excellent backwashing effect in the above two typical working conditions. It only improves the strength of the ordinary non-symmetrical powder sintered filter element, and can only be used in small working conditions with strength requirements, which has very limited economic benefits. In addition, the non-symmetrical sintered filter element made by this process method has extremely harsh requirements for base material rolling, filter material rolling, and welding process. Any mistake in any link is fatal, so the product scrap rate is also relatively high. SUMMARY

[0008] The technical problem solved by the present application is to provide a large-flux, high-precision and high-strength metal powder coating sintered mesh filter tube, which effectively solves the problem that the precision, flux and strength of the existing metal powder and wire mesh composite filter tube cannot be considered simultaneously, effectively solves the leakage and layer opening risk of the existing welded longitudinal seam filter tube, and effectively avoids the damage to the metal film layer caused by the traditional film coating process reel processing.

[0009] To solve the above technical problems, the present application adopts the following technical solution: a large-flux metal powder coating sintered mesh filter tube, characterized in that it comprises a tubular multi-layer sintered mesh base material formed by rolling and welding, and a metal film filter layer arranged on the outer surface of the tubular multi-layer sintered mesh base material.

[0010] Further limited, the tubular multi-layer sintered mesh base material is arranged in a gradually changing aperture with 3-5 layers of metal wire mesh, wherein the innermost layer is a 12x64 mesh, and the receiving surface of the film coating filter layer is a mesh with a mesh number of 100-350.

[0011] The preparation process of the large-flux metal powder coating sintered mesh filter tube according to the present application is characterized in that the specific process is as follows: ultra-fine metal powder with a mesh number of 2000-2500 is dispersed into an organic solvent polyvinyl alcohol or polyacrylate to form a uniform slurry, and a ultra-thin metal powder filter layer is coated on the outer surface of the tubular multi-layer sintered mesh base material formed by rolling, by using the principle of liquid high-temperature atomization. During the manufacturing process, the tubular multi-layer sintered mesh base material is rotated at a high speed to obtain a ultra-thin film coating filter layer. By adjusting the rotation speed of the tubular multi-layer sintered mesh base material and the input amount of the slurry, a film coating filter layer with a thickness of at least 0.05mm can be achieved, and finally a large-flux, high-precision and high-strength metal powder coating sintered mesh filter tube is obtained.

[0012] Further limited, the preparation process of the large-flux metal powder coating sintered mesh filter tube is characterized in that the specific steps are as follows:

[0013] Step S1: Preparation of tubular multi-layer sintered mesh base material

[0014] According to the working condition requirements, 3-5 layers of metal wire mesh are arranged in a gradually changing aperture, generally the innermost layer is a 12x64 mesh, and the receiving surface of the film coating filter layer is a mesh. According to the precision of the target product, the mesh number of the mesh receiving surface of the film coating filter layer is generally selected to be 100-350. After the metal wire mesh is laid according to the design scheme, vacuum sintering is performed. The sintered metal wire mesh is rolled into a tubular shape and welded longitudinally to obtain a tubular multi-layer sintered mesh base material.

[0015] Step S2: Preparation of high-precision film coating filter layer

[0016] The superfine metal powder with 2000-2500 mesh and the organic solvent polyvinyl alcohol or polyacrylate are mixed in a volume ratio of 1:4-6, and then stirred and dispersed uniformly to form a slurry; the prepared slurry is placed in a heating container, the temperature is adjusted to the boiling point of the solvent, and the compressed air pressure is adjusted to 0.6 MPa, and when the slurry is in the state of atomization, the film coating is prepared on the tubular multi-layer sintered mesh substrate; the tubular multi-layer sintered mesh substrate is placed in a device that is sealed from the outside and is high-speed rotating, the atomized slurry is slowly introduced, and the timing is started, and the thickness of the filter layer is controlled by adjusting the input amount of the slurry and the rotating speed of the tubular multi-layer sintered mesh substrate;

[0017] Step S3: filter tube vacuum sintering process

[0018] The tubular multi-layer sintered mesh substrate after coating is loaded into a vacuum sintering furnace for sintering, the first stage is heated at a rate of 2℃ / min, and when the temperature rises to 250℃, it is kept for 1h; the second stage is heated at a rate of 2℃ / min to 600℃, and kept for 1h; the third stage is rapidly heated at a rate of 20℃ / min to 900℃, and kept for 1h; the fourth stage is heated at a rate of 2℃ / min to 1150℃, and kept for 2h;

[0019] Step S4: filter tube cooling process

[0020] After sintering is completed, the temperature is reduced at a rate of 2℃ / min to 850℃, and kept for 10min, then argon gas is introduced into the sintering furnace, and the temperature is further reduced at a rate of 5℃ / min to room temperature, and a large-flux metal powder coated sintered mesh filter tube is obtained after the furnace is discharged.

[0021] Compared with the prior art, the present application has the following beneficial effects: the existing metal powder and metal wire mesh composite filter tube on the market adopts a rolled flaky sintered wire mesh, and then a film layer is coated on the surface of the wire mesh through a supersonic spraying device. During spraying, the flaky material is static, and the spraying device sprays the powder slurry at the surface of the wire mesh at a supersonic speed according to a programmed track. Under this process, the powder of the film layer is often guided to the middle layer of the wire mesh due to the high-pressure high-speed airflow, and the thickness of the film layer is generally 0.5-1 mm and the density is large, which is not conducive to the formation of high porosity. The difference between the present application and other metal powder and metal wire mesh composite filter element lies in that an advanced gas atomization plating process is invented. The process disperses 2000-2500 mesh super fine metal powder in a specific organic solvent, and a super thin metal powder filter layer is plated on the multi-layer sintered mesh base pipe formed by a winding drum by using the liquid high temperature atomization principle. During production, the high-speed rotation of the tubular multi-layer sintered mesh base material can obtain a super thin plated film filter layer. The plating of the super fine metal powder and the sintered metal wire mesh plated surface combined with the gas atomization plating film process can greatly reduce the thickness of the plated film filter layer, and the thinnest plated film filter layer can be 0.05 mm. According to the theoretical prototype of the technical scheme, the thinner the thickness of the high-precision film layer, the smaller the differential pressure during filtration. This process exactly meets the necessary conditions for obtaining a large flux, high strength and high-precision filter element, and is suitable for special working conditions.

[0022] The super fine metal powder plating process adopted by the present application attaches a super fine metal plated film filter layer to the outer surface of the tubular multi-layer sintered mesh base material by using special equipment. Since the plating layer is attached to the surface of the tubular sintered metal wire mesh element, the plated film filter layer on the outer surface of the filter tube is integrated, compared with the filter tube which is made by rolling sheet material and then coating a film layer and then winding and welding, the leakage risk and poor fatigue strength caused by the weld of the film layer are solved. This process can well balance the filtering performance and high strength regeneration environment, and the separation precision of the filter tube made by this method can be up to 0.3 μm. The metal powder and metal wire mesh composite filter tube is made by rolling a sintered mesh plate material, vacuum sintering the base material, then spraying a film layer, vacuum sintering again, winding into a pipe, and finally welding the longitudinal seam to obtain the filter tube. Although this method can obtain better strength compared with the traditional asymmetric powder sintered filter element, the filtering precision and fatigue strength are still insufficient to adapt to long-term extreme working conditions. Because the pore structure of the winding factor itself is damaged by the later processing, and there is a certain risk of welding leakage during the longitudinal seam welding process after the winding into a tubular element, because of the heat affected factor, there will be a certain fracture zone on both sides of the weld seam, which brings uncertainty to the future use process.

[0023] The filter tube of this invention consists of a powder coating (ultrafine powder) and a support layer (multi-layer sintered mesh) arranged sequentially in the direction of media entry, according to the product's precision requirements. The support layer, a multi-layer sintered mesh, can be optimized to achieve a gradually changing pore size based on operating conditions. During normal filtration, the media enters from one side of the coating, and contaminants are trapped and continuously accumulate by the high-precision coating. As the differential pressure increases, clean, high-pressure fluid is drawn from inside the filter element to clean and regenerate the filter cake formed on the outer surface. This integrated coating with a gradually changing pore size is easier to backwash and regenerate than sheet-like composite filter elements, requiring less backwash pressure and system energy consumption. The integrated coating's bonding strength and integrity are significantly superior to welded composite membrane materials, which have inherent defects due to weld seams, under fatigue conditions, making it particularly suitable for long-term operation under high temperature and high pressure. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an existing composite filter material made of metal powder and metal wire mesh.

[0025] Figure 2 This is a schematic diagram of an existing composite filter tube structure made of metal powder and metal wire mesh;

[0026] Figure 3 This is a schematic diagram of the structure of the high-throughput metal powder coated sintered mesh filter tube in this invention;

[0027] Figure 4 This is a curve comparing the flow rate of the filter tube of this invention with that of existing filter tubes;

[0028] Figure 5 This is a graph showing the performance (outlet emission concentration) of the existing filter tubes;

[0029] Figure 6 This is a graph showing the performance (outlet emission concentration) of the filter tube of this invention.

[0030] In the figure: 1-Tubular multilayer sintered mesh substrate, 2-Metal membrane filter layer. Detailed Implementation

[0031] The technical solution of the present invention is described in detail with reference to the accompanying drawings. A high-throughput metal powder coated sintered mesh filter tube includes a tubular multilayer sintered mesh substrate 1 formed by rolling and welding, and a metal membrane filter layer 2 disposed on the outer surface of the tubular multilayer sintered mesh substrate 1.

[0032] Filtration mechanisms are broadly classified into two categories: surface filtration (cake filtration) and depth filtration. As the names suggest, surface filtration traps particulate matter on the surface of the filter element, while depth filtration traps particulate matter within the pores of the filter medium. Because filters require long-term stable operation and undergo backwashing and regeneration, the operating principle dictates that only surface filtration can achieve long-term stable operation. Based on the surface filtration operating mode, the operating pressure difference during filter operation satisfies Darcy's fluid theory: , V-flow, d-filter layer thickness, eta-medium viscosity, S-filter area, alpha-permeability coefficient of the filter material, according to the Darcy fluid theory, the flow through the filter element is inversely proportional to the filtering accuracy and thickness of the filter element. Therefore, to obtain a high-flow filter core, the asymmetric structure of the aperture gradient type is in line with the design principle. Under the condition of ensuring the strength of the filter element, reducing the thickness of the filter layer (metal plated film filter layer) is the inevitable choice to reduce the resistance and improve the flux.

[0033] The preparation process of the large-flow metal powder plated sintered mesh filter tube is as follows:

[0034] Step S1: preparation of a tubular multi-layer sintered mesh base material

[0035] According to the working condition requirements, 4 layers of metal wire meshes are arranged in a gradually changing aperture, and the innermost layer is generally a 12x64 mesh, and the plated film filter layer receiving surface is a mesh. According to the accuracy of the target product, the mesh number of the plated film filter layer receiving surface is generally selected to be 200 meshes. After the metal wire meshes are laid according to the design scheme, vacuum sintering is performed. The sintered metal wire meshes are rolled into a tubular shape and welded longitudinally to obtain a tubular multi-layer sintered mesh base material.

[0036] Step S2: preparation of a high-precision plated film filter layer

[0037] The 2000~2500 mesh ultra-fine metal powder and the organic solvent polyvinyl alcohol or polyacrylate are mixed and stirred in a volume ratio of 1:5 to uniformly disperse the slurry. The prepared slurry is placed in a heating container, the temperature is adjusted to the boiling point of the solvent, and the compressed air pressure is adjusted to 0.6MPa. When the slurry is in an atomized state, the preparation of the plated film on the tubular multi-layer sintered mesh base material is prepared. The tubular multi-layer sintered mesh base pipe is placed in a device that is sealed from the outside and rotates at high speed, the atomized slurry is slowly introduced, and the timing is started. By adjusting the input amount of the slurry and the rotating speed of the tubular multi-layer sintered mesh base material, the thickness of the plated film filter layer is controlled.

[0038] Step S3: vacuum sintering process of the filter tube

[0039] The tubular multi-layer sintered mesh base material after plating is loaded into a vacuum sintering furnace for sintering. In the first stage, the temperature is raised at a rate of 2℃ / min, and when the temperature rises to 250℃, the temperature is maintained for 1h. In the second stage, the temperature is raised at a rate of 2℃ / min to 600℃, and the temperature is maintained for 1h. In the third stage, the temperature is rapidly raised at a rate of 20℃ / min to 900℃, and the temperature is maintained for 1h. In the fourth stage, the temperature is raised at a rate of 2℃ / min to 1150℃, and the temperature is maintained for 2h.

[0040] Step S4: filter tube cooling process

[0041] After sintering is completed, the temperature is decreased to 850℃ at a rate of 2℃ / min, and the temperature is kept for 10min, then argon is introduced into the sintering furnace, and the temperature is continuously decreased to room temperature at a rate of 5℃ / min, and the sintered wire mesh filter tube with large flux metal powder coating is obtained after discharging from the furnace.

[0042] The gas atomization coating process in the application avoids the damage to the coating layer caused by the traditional film coating process of the winding drum processing, and the sintered wire mesh ultra-thin metal coating large flux asymmetric filter tube and the gas atomization coating process have low production cost and low requirement for production equipment, and are suitable for large-scale industrial production. The flow flux of the asymmetric structure filter core prepared by the method is much higher than that of the traditional asymmetric sintered filter core, and the gradual aperture design of the filter tube is also different from the traditional one, so that the method can be widely applied to gas-solid and liquid-solid separation in the petroleum and chemical industry, coal industry, water treatment, biological pharmaceutical industry and other industries, and is especially suitable for fatigue working conditions with high temperature, high impurity content, high viscosity, high precision and online regeneration demand for filter cores. Typical applications include ME-101 yield increase project of S-Zorb device for adsorption desulfurization of catalytic gasoline, ACO light oil processing catalyst slurry filtration, coal gasification fly ash filtration, nylon plant lactam hydroxylamine oximation process catalyst recovery, methanol to olefin process water slurry filtration, and chemical plant alkali-containing wastewater filtration and other industrial fields. Figure 4 The filter tube of the application and the existing filter tube flow flux comparison curve; Figures 5-6 The filter tube of the application and the existing filter tube performance (outlet emission concentration) comparison chart.

[0043] The above shows and describes the basic principles, main features and advantages of the application, and the application has various changes and improvements without departing from the spirit and scope of the application, and these changes and improvements fall within the scope of the application.

Claims

1. A high-throughput metal powder coated sintered mesh filter tube, characterized in that... The material includes a tubular multilayer sintered mesh substrate formed by rolling and welding, and a metal membrane filter layer disposed on the outer surface of the tubular multilayer sintered mesh substrate. The tubular multilayer sintered mesh substrate is composed of 3 to 5 layers of metal wire mesh arranged in a gradually changing aperture, wherein the innermost layer is a 12×64 woven mesh, and the receiving surface of the coated filter layer is a mesh with a mesh number of 100 to 350. The specific preparation process of this high-throughput metal powder coated sintered mesh filter tube is as follows: 2000-2500 mesh ultrafine metal powder is dispersed in an organic solvent, polyvinyl alcohol or polyacrylate, to form a uniform slurry. An ultrathin metal powder filter layer is coated on the outer surface of a rolled tubular multilayer sintered mesh substrate. The temperature is adjusted to the boiling point of the solvent, and the compressed air pressure is adjusted to 0.6 MPa. When the slurry emerges in an atomized state, it is ready to be coated on the tubular multilayer sintered mesh substrate. During the manufacturing process, the tubular multilayer sintered mesh substrate rotates at high speed to obtain an ultrathin coated filter layer. By adjusting the rotation speed of the tubular multilayer sintered mesh substrate and the input amount of the slurry, a minimum coated filter layer thickness of 0.05 mm can be achieved, thus ultimately producing a high-throughput, high-precision, and high-strength metal powder coated sintered mesh filter tube.

2. The preparation process of the high-throughput metal powder coated sintered mesh filter tube according to claim 1, characterized in that... The specific steps are as follows: Step S1: Preparation of tubular multilayer sintered mesh substrate Select 3 to 5 layers of metal wire mesh arranged in a gradient aperture according to the working conditions. Generally, the innermost layer is a 12×64 woven mesh. The receiving surface of the coating filter layer is a mesh. Depending on the precision of the target product, the mesh count of the receiving surface of the coating filter layer is generally selected as 100~350 mesh. After laying the metal wire mesh according to the design plan, vacuum sintering is performed. The sintered metal wire mesh is rolled into a tube and welded with longitudinal seams to obtain a tubular multi-layer sintered mesh substrate. Step S2: Preparation of high-precision coated filter layer 2000-2500 mesh ultrafine metal powder and organic solvent polyvinyl alcohol or polyacrylate are mixed at a volume ratio of 1:4-6 and stirred to disperse evenly to form a slurry. The prepared slurry is placed in a heating container, the temperature is adjusted to the boiling point of the solvent, and the compressed air pressure is adjusted to 0.6 MPa. When the slurry emerges in an atomized state, it is ready to be coated on the tubular multilayer sintered mesh substrate. The tubular multilayer sintered mesh base tube is placed in a high-speed spin-fitting device that is sealed from the outside world. The atomized slurry is slowly introduced and the timing is started. The thickness of the coated filter layer is controlled by adjusting the slurry input and the rotation speed of the tubular multilayer sintered mesh substrate. Step S3: Vacuum sintering process for filter tubes The coated tubular multilayer sintered mesh substrate was loaded into a vacuum sintering furnace for sintering. In the first stage, the temperature was increased at a rate of 2℃ / min, and held at 250℃ for 1 hour. In the second stage, the temperature was increased at a rate of 2℃ / min to 600℃ and held for 1 hour. In the third stage, the temperature was rapidly increased at a rate of 20℃ / min to 900℃ and held for 1 hour. In the fourth stage, the temperature was increased at a rate of 2℃ / min to 1150℃ and held for 2 hours. Step S4: Filter tube cooling process After sintering, the temperature is lowered to 850℃ at a rate of 2℃ / min, held for 10 minutes, and then argon gas is introduced into the sintering furnace and the temperature is further lowered to room temperature at a rate of 5℃ / min. After exiting the furnace, a high-throughput metal powder coated sintered mesh filter tube is obtained.

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