Metal powder sintered filter element and preparation method thereof

Abstract

The purpose of the present invention is to provide a method for preparing a metal powder sintered filter element, by adding porous calcium carbonate powder, high pressure pressing is used during the pressing process, calcium carbonate can play a supporting role, calcium carbonate decomposes to produce carbon dioxide and calcium oxide during the firing process, and calcium oxide powder plays a supporting role after high pressure pressing to form micropores, and calcium oxide in the filter element is washed away by dilute acid soaking, and finally the filter element is welded by tube winding. The metal powder filter element prepared by the present invention can simultaneously obtain high precision, high flux and excellent backwashing effect, and a longer service life.

Description

Technical Field

[0001] The invention relates to the field of metal powder metallurgy products, and in particular to the preparation of a metal powder sintered filter element. Background Art

[0002] At present, the entire filter industry requires the filter material to have as large a filtration flow as possible, and the filter itself must have a very small filtration resistance, so as to achieve the purpose of reducing energy consumption. However, in fact, there is often such a contradiction for ordinary filters: under the condition of large filtration flux, the filtration accuracy is often not high; and when the filtration accuracy needs to be improved, the filtration flux will drop sharply. The reason for this phenomenon is that during the pressing process, it is necessary to press within a certain pressure range. If the pressure is too low, the filtration accuracy of the finished filter element will not meet the requirements. If the pressure is too high, the accuracy of the finished filter element will meet the requirements but the flow rate will be reduced. In some special occasions, such as the ordinary metal filter element in the petrochemical S-Zorb adsorption desulfurization device, the number of equipment required for the filter element with ordinary structure is large. At the same time, the filter element is not easy to backwash due to its own structure. As a result, the filter element is scrapped after about one year of use due to blockage and reduced flow rate, which seriously affects the normal production. Summary of the invention

[0003] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a metal powder sintered filter element. By adding porous calcium carbonate powder and adopting high-pressure pressing during the pressing process, calcium carbonate can play a supporting role. During the firing process, calcium carbonate decomposes to produce carbon dioxide and calcium oxide. After high-pressure pressing, the calcium oxide powder plays a supporting role and forms micropores. The calcium oxide in the filter element is soaked and washed away by dilute acid, and finally the filter element is welded by tube winding.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for preparing a metal powder sintered filter element, characterized in that the filter element preparation process steps are:

[0006] (1) Powder screening: filter element metal powder screening, the powder particle size is -300+1000 mesh; porous powder screening, the powder particle size is -300+500 mesh.

[0007] (2) Mixing: The filter element metal powder and the pore-forming powder in step (1) are uniformly mixed in a weight ratio of (30-40) : 1.

[0008] (3) Low-pressure pressing: The mixture in step (2) is filled into a shaping mold and pressed into a plate-shaped green embryo at a pressing pressure of 100-200 MPa.

[0009] (4) Sintering: The green embryo prepared in step (3) is placed in a vacuum environment and sintered at 1400-1800° C. for 0.5-1 hour.

[0010] (5) High-pressure pressing: The filter plate sintered in step (4) is pressed at 800-1000 MPa.

[0011] (6) Rinse: Soak the filter plate in dilute acid for 20 to 30 minutes, and then rinse the filter plate with deionized water for 5 to 10 minutes.

[0012] (7) Tube rolling and welding: The filter plate in step (6) is rolled into a tube shape by a plate rolling machine, and then the longitudinal seam is welded by full welding.

[0013] The filter element metal powder is austenitic stainless steel or duplex stainless steel.

[0014] The pore-forming powder is calcium carbonate.

[0015] The dilute acid solution is a nitric acid solution with a mass concentration of 3% to 10%, and a corrosion inhibitor is added in an amount of 0.1% to 1% of the mass of the nitric acid solution.

[0016] A metal powder sintered filter element, wherein the filter element is prepared by the preparation method described in any one of claims 1 to 4.

[0017] The average gap width of the filter element is 2.5-1.0 μm, and the length is 20-40 μm.

[0018] The filter element has a thickness of 1-5 mm, a length of 50-1000 mm, and an inner diameter of 20-500 mm.

[0019] Beneficial effects of the present invention: The metal powder filter element prepared by the present invention can simultaneously obtain high precision, high flux and excellent backwashing effect, and a longer service life. DETAILED DESCRIPTION

[0020] A method for preparing a metal powder sintered filter element, characterized in that the filter element preparation process steps are:

[0021] (1) Powder screening: filter element metal powder screening, the powder particle size is -300+1000 mesh; porous powder screening, the powder particle size is -300+500 mesh.

[0022] (2) Mixing: The filter element metal powder and the pore-forming powder in step (1) are uniformly mixed in a weight ratio of (30-40) : 1.

[0023] (3) Low-pressure pressing: The mixture in step (2) is filled into a shaping mold and pressed into a plate-shaped green embryo at a pressing pressure of 100-200 MPa.

[0024] (4) Sintering: The green embryo prepared in step (3) is placed in a vacuum environment and sintered at 1400-1800° C. for 0.5-1 hour.

[0025] (5) High-pressure pressing: The filter plate sintered in step (4) is pressed at 800-1000 MPa.

[0026] (6) Rinse: Soak the filter plate in dilute acid for 20 to 30 minutes, and then rinse the filter plate with deionized water for 5 to 10 minutes.

[0027] (7) Tube rolling and welding: The filter plate in step (6) is rolled into a tube shape by a plate rolling machine, and then the longitudinal seam is welded by full welding.

[0028] The filter element metal powder is austenitic stainless steel or duplex stainless steel.

[0029] The pore-forming powder is calcium carbonate.

[0030] The dilute acid solution is a nitric acid solution with a mass concentration of 3% to 10%, and a corrosion inhibitor is added in an amount of 0.1% to 1% of the mass of the nitric acid solution.

[0031] A metal powder sintered filter element, wherein the filter element is prepared by the preparation method described in any one of claims 1 to 4.

[0032] The average gap width of the filter element is 2.5-1.0 μm, and the length is 20-40 μm.

[0033] The filter element has a thickness of 1-5 mm, a length of 50-1000 mm, and an inner diameter of 20-500 mm.

[0034] A metal powder sintered filter element is prepared by the above preparation method.

[0035] The average gap width of the filter element is 2.5-1.0 μm, and the length is 20-40 μm.

[0036] The filter element has a thickness of 1-5 mm, a length of 50-1000 mm, and an inner diameter of 20-500 mm.

[0037] Preparation method of austenitic stainless steel powder sintered filter element:

[0038] The filter element metal powder is screened, and the powder particle size is -300+1000 mesh; the porous powder is screened, and the powder particle size is -300+500 mesh.

[0039] The filter element metal powder and the pore-forming metal powder are mixed evenly at a weight ratio of 30:1.

[0040] The mixture is filled into a shaping mold to form a green embryo in a plate shape at a pressing pressure of 100 MPa.

[0041] The green embryo was placed in a vacuum environment and sintered at 1500°C for 1 hour.

[0042] The sintered filter plate was pressed at a pressure of 800 MPa.

[0043] The filter plate was immersed in dilute acid for 30 minutes, and then the filter element was rinsed with deionized water for 5 minutes; the dilute acid solution was a nitric acid solution with a mass concentration of 3%, and a corrosion inhibitor was added at 0.1% of the mass of the nitric acid solution.

[0044] The average gap width of the prepared filter element is 2.5~1.0μm, the length is 20~40μm, the length is 1000mm, and the inner diameter is 500mm.

[0045] Preparation method of duplex stainless steel powder sintered filter element:

[0046] The filter element metal powder is screened, and the powder particle size is -300+1000 mesh; the porous powder is screened, and the powder particle size is -300+500 mesh.

[0047] The filter element metal powder and the pore-forming metal powder are mixed evenly at a weight ratio of 40:1.

[0048] The mixture is filled into a shaping mold to press a plate-shaped green embryo at a pressing pressure of 150 MPa.

[0049] The green embryo was placed in a vacuum environment and sintered at 1800°C for 0.5 hours.

[0050] The sintered filter plate was pressed at a pressure of 900 MPa.

[0051] The filter plate was immersed in dilute acid for 20 minutes, and then the filter element was rinsed with deionized water for 10 minutes; the dilute acid solution was a nitric acid solution with a mass concentration of 10%, and a corrosion inhibitor was added at a concentration of 1% of the mass of the nitric acid solution.

[0052] The average gap width of the prepared filter element is 2.5~1.0μm, the length is 20~40μm, the length is 500mm, and the inner diameter is 250mm.

[0053] Preparation method of mixed sintered filter element of austenitic stainless steel powder and duplex stainless steel powder:

[0054] The filter element metal powder is screened, and the powder particle size is -300+1000 mesh; the porous powder is screened, and the powder particle size is -300+500 mesh.

[0055] The filter element metal powder and the pore-forming metal powder are mixed evenly at a weight ratio of 35:1.

[0056] The mixture is filled into a shaping mold to form a green embryo in a plate shape at a pressing pressure of 200 MPa.

[0057] The green embryo was placed in a vacuum environment and sintered at 1800°C for 0.8 hours.

[0058] The sintered filter plate was pressed at a pressure of 1000 MPa.

[0059] The filter plate was immersed in dilute acid for 25 minutes, and then the filter element was rinsed with deionized water for 5 minutes; the dilute acid solution was a nitric acid solution with a mass concentration of 6%, and a corrosion inhibitor was added at a concentration of 0.5% of the mass of the nitric acid solution.

[0060] The average gap width of the prepared filter element is 2.5~1.0μm, and the length is 20~40μm; the filter element thickness is 1mm; the length is 50mm; and the inner diameter is 20mm.

[0061] The prepared metal powder sintered filter element was installed in the S-Zorb adsorption desulfurization device for test detection, wherein Table 1 shows the on-site filtration performance of the metal powder sintered filter element, and Table 2 shows the pressure difference comparison between the reactor and the filter within one cycle.

[0062] It can be seen from the table that the metal powder filter element prepared by the present invention can simultaneously obtain high precision, high flux and excellent backwashing effect, and a longer service life.

[0063] Table 1

[0064]

[0065] Table 2

[0066]

Claims

1. A method for preparing a metal powder sintered filter element, characterized in that The filter element preparation process steps are: (1) Powder screening Filter element metal powder screening, powder particle size is -300+1000 mesh; The pore-forming powder is screened, and the powder particle size is -300+500 mesh; the pore-forming powder is calcium carbonate; (2) Mixed The filter element metal powder and the pore-forming powder in step (1) are mixed uniformly at a weight ratio of (30-40):1; (3) Low pressure suppression The mixture in step (2) is filled into a shaping mold and pressed into a plate-shaped green embryo at a pressing pressure of 100-200 MPa; (4) Sintering The green embryo in step (3) is placed in a vacuum environment and sintered at 1400-1800° C. for 0.5-1 hour; (5) High pressure pressing The filter plate sintered in step (4) is pressed at 800-1000 MPa; (6) Flushing Soak the filter plate in dilute acid for 20 to 30 minutes, and then rinse the filter plate with deionized water for 5 to 10 minutes; (7) Pipe rolling and welding The filter plate in step (6) is rolled into a tube by a plate rolling machine, and then the longitudinal seam is welded by full welding.

2. The method for preparing a metal powder sintered filter element according to claim 1, characterized in that: The filter element metal powder is austenitic stainless steel or duplex stainless steel.

3. The method for preparing a metal powder sintered filter element according to claim 1, characterized in that: The dilute acid solution is a nitric acid solution with a mass concentration of 3% to 10%, and a corrosion inhibitor is added in an amount of 0.1% to 1% of the mass of the nitric acid solution.

4. A metal powder sintered filter element, characterized in that: The filter element is prepared by the preparation method described in any one of claims 1 to 3.

5. The metal powder sintered filter element according to claim 4, characterized in that: The filter element has an average pore width of 2.5-1.0 μm and a length of 20-40 μm.

6. The metal powder sintered filter element according to claim 5, characterized in that: The filter element has a thickness of 1-5 mm, a length of 50-1000 mm, and an inner diameter of 20-500 mm.

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