Filter and filter element

Abstract

The invention relates to the field of mechanical engineering, and more particularly to filter elements used in filters for purifying liquid and gaseous media. What is proposed is a filter element comprising a hollow permeable support body with a closed cross section, over which is mounted a filter screen that is covered on top by a protective body, the filter element being characterized in that the support body is made of a resilient material, and the filter screen is a sleeve made of a resilient filtering material having a set filtration fineness, wherein the perimeter of the filter screen is smaller in cross section than the perimeter of the support body by 2-5%. Also proposed is a filter comprising the above-described filter element. The technical result consists in rendering the filter element capable of self-cleaning when in operation, while also providing and maintaining a set filtration fineness.

Description

[0001] FILTER AND FILTER ELEMENT

[0002] The invention relates to the field of mechanical engineering, in particular to filter elements used in filters for purifying liquid and gaseous media.

[0003] A filter for downhole use is known, which includes a hollow filter housing, including filter material, and a perforated separator, which surrounds the filter housing and is plastically deformed radially inward towards the outer periphery of the filter housing in such a way that the outer periphery of the filter housing can contact the inner periphery of the filter housing along the entire circumference of the filter housing without exceeding the maximum permissible elongation of the filter housing (according to patent US6382318, IPC E21B 43 / 04, published 07.05.02).

[0004] The disadvantage of this filter is that the filter layers are made identical and during operation of the filter, the main work of trapping particles is performed by only one outer layer, which also lacks the filter's ability to regenerate.

[0005] An expandable filter assembly for downhole use is known, comprising a base pipe having an internal surface, a longitudinal axis and a plurality of openings; at least one filter layer installed above said base pipe, the filter layer being annealed to facilitate subsequent expansion in the well (according to patent US6607032, IPC E21B 43 / 08, published 19.08.03).

[0006] A disadvantage of this filter is the lack of self-cleaning capability for the filter unit during operation. A detachable well filter is known, comprising a supporting frame made of perforated pipe. Filter elements are mounted on the pipe between two stops. Each filter element is made of wire material pressed into perforated housings, which are mounted on the perforated pipe with a gap that serves as an internal drainage layer. Adjacent housings partially overlap due to the fact that one side of the housing is designed with an annular cavity, the outer diameter of which is equal to or smaller than the inner diameter of the other side of the housing (according to patent RU2348795, IPC E21B 43 / 08, published March 10, 2009).

[0007] The disadvantage of this design is that during operation, the filter with filter elements made of pressed wire material initially does not have the specified filtration fineness due to the peculiarities of the manufacturing technology and reaches it when it becomes partially clogged, which requires periodic cleaning or replacement.

[0008] The closest technical solution is a filter element comprising a supporting frame and a filter screen consisting of at least two layers. Specifically, it has a protective frame and drainage layers located either outside the filter screen or between its layers. The filter screen is elastically stretched. The entire filter can be constructed using this filter element (according to patent RU2703038, IPC E21B 43 / 08, published October 15, 2019).

[0009] The known filter element implements self-cleaning by maintaining the filter screen in an elastically stretched state. When the medium stops flowing through the filter element, the filter screen, further stretched by the pressure difference created by its resistance, returns to its original state, ensuring the removal of particles trapped on the filter screen. However, the pre-stretching of the filter screen, made of wire mesh, negatively impacts filtration efficiency. Pre-stretching the filter screen increases the distance between the filter fibers, which negatively impacts filtration efficiency, as the filter will initially pass larger particles.

[0010] The technical result achieved by using the proposed invention consists in providing the possibility of self-cleaning of the filter element during operation while ensuring and maintaining the specified filtration fineness.

[0011] The said technical result is achieved in that the filter element contains a permeable supporting frame that is hollow inside and closed in cross-section, on top of which a filter screen is installed, closed on top by a protective frame, and is distinguished by the fact that the supporting frame is made of an elastic material, the filter screen is a sleeve made of an elastic filter material with a given filtration fineness, while the perimeter of the filter screen in cross-section is less than the perimeter of the supporting frame by 2-5%.

[0012] The technical result is also achieved in that the filter contains end parts rigidly connected to each other, and at least one filter element, which includes a permeable supporting frame that is hollow inside and closed in cross-section, on top of which a filter screen is installed, closed from above by a protective frame, and is characterized in that in the filter element the supporting frame is made of an elastic material, the filter screen is a sleeve made of an elastic filter material with a given filtration fineness, while the perimeter of the filter screen in cross-section is less than the perimeter of the supporting frame by 2-5%.

[0013] Additionally, the supporting frame can be made of permeable wire, mesh, or other permeable structures. Furthermore, the filter material, with a specified filtration fineness, can have hydrophobic and oleophobic properties, corrosion resistance, and heat resistance up to 600°C.

[0014] The proposed invention is illustrated by the following drawings:

[0015] Fig. 1 - filter element, general view with section;

[0016] Fig. 2 - filter element, cross section;

[0017] Fig. 3, 4 - operation of the filter element;

[0018] Fig. 5 - filter with filter element, longitudinal section;

[0019] Fig. 6 - dependence of the average value of the pressure drop on the air flow;

[0020] Fig. 7 - dependence of the average value of the pressure drop on the test duration;

[0021] Fig. 8 - dependence of the average value of the filtration coefficient on the granulometric composition of the pollutant.

[0022] The filter element (Fig. 1, 2) contains a permeable supporting frame 1, hollow inside and closed in cross-section, a filter screen 2 and a protective frame 3.

[0023] The supporting frame 1 is made of wire-permeable, mesh or any other elastic material.

[0024] Filter screen 2 is a sleeve made of elastic filter material with a specified filtration fineness. Such materials may include, for example, polyphenylene sulfide, polytetrafluoroethylene (PTFE), polyester, polyamide (aramid), as well as fabrics made of basalt (silica), fiberglass, and others.

[0025] The protective frame 3 is made of a metal mesh, a perforated pipe or any other material that ensures protection of the filter screen 2 from damage and the passage of the filtered medium.

[0026] In cross-section, the filter element can have the shape of a circle, an ellipse, a polygon or any other closed shape.

[0027] The perimeter of the filter screen in cross-section is 2-5% smaller than the perimeter of the supporting frame. This range was chosen due to the elastic properties of the materials from which supporting frame 1 and filter screen 2 are made. Supporting frame 1 has an elastic elongation (compression) of up to 2%, while the filter fabrics from which filter screen 2 is made have an elastic elongation (compression) of 5-9%.

[0028] Filter screen 2, due to its perimeter being smaller than that of supporting frame 1, is in an elastically stretched state. During operation, as the filtered medium passes through the filter element (Fig. 3), a pressure differential is created on the surface of filter screen 2 due to its hydraulic resistance, which increases as the filter becomes clogged. In this case, filter screen 2, together with the elastic supporting frame 1, bends in the direction of the flow. To clean the filter element, it is necessary to stop the flow of the medium; due to their elastic properties, the pre-stretched filter screen 2 and supporting frame 1 will return to their original position (Fig. 4). This will remove particles 4 from the surface of filter screen 2.

[0029] The proposed filter element can be used in filters, for example, well filters (Fig. 5) with the required (specified) filtration fineness (from 2 μm), used for filtering formation fluid from mechanical impurities. The well filter shown in Fig. 5 consists of end parts - head 5 and base 6, rigidly connected by a pipe 7, and filter elements 8, preferably of cylindrical shape. To confirm the advantages of the claimed filter element, comparative tests were conducted for regeneration (self-cleaning) with filter elements made of permeable wire material (PWM) and wire mesh. The following participated in the tests on a gaseous medium (air):

[0030] 1) filter element 1 made of 1П1М, material 12Х18Н10Т, filtration fineness 100 µm;

[0031] 2) filter element 2 made of mesh C 160 GOST 3187-76, filtration fineness 70-95 µm;

[0032] 3) filter element 3 according to the claimed invention, with a nominal filtration fineness of 100 µm.

[0033] Electrocorundum 25A F150 GOST 3647-80 was used as a pollutant.

[0034] The following results were obtained:

[0035] - maximum average pressure drop, with an air flow of 9 m 3 / h: filter element 1 - 104.3 Pa, filter element 2 - 125 Pa, filter element 3 - 40.5 Pa. The dependence of the average value of the pressure drop on the air flow rate is shown in Fig. 6;

[0036] - maximum average pressure drop, with an air flow of 9 m 3 / h and the total duration of the tests: filter element 1 - 511.1 Pa, filter element 2 - 492.1 Pa, filter element 3 - 77.6 Pa. The dependence of the average value of the pressure drop on the duration of the test is shown in Fig. 7;

[0037] - average value of nominal filtration fineness: filter element 1 — more than 125 μm, filter element 2 — 75 μm, filter element 3 — 90 μm. The dependence of the average value of the filtration coefficient on the granulometric composition of the pollutant is shown in Fig. 8; - degree of regeneration: filter element 1 — 86.8%, filter element 2 — 87.5%, filter element 3 — 89.18%.

[0038] As can be seen from the obtained test results, the filter element, according to the claimed invention, has the best self-cleaning (regeneration) ability and at the same time has the lowest hydraulic resistance and maintains the nominal filtration fineness for a long time.

[0039] The proposed filter element design allows the filter screen to expand in only one direction, perpendicular to the filter element's longitudinal axis. As a result, the filter material's pore size in the longitudinal direction remains constant during expansion, ensuring the specified filtration fineness. At the same time, expansion of the filter material enables the filter element to self-clean during operation.

[0040] The filter material's hydrophobic and oleophobic properties, corrosion resistance, and heat resistance up to 600°C help maintain its properties and ensure better cleaning throughout the entire service life of the filter element.

[0041] Thus, the solutions described in the invention make it possible to ensure the self-cleaning of the filter element during operation while maintaining the specified filtration fineness and contribute to the achievement of the technical result.

Claims

CLAUSES OF THE INVENTION 1. A filter element containing a permeable supporting frame made of elastic material, hollow inside and closed in cross-section, on top of which a filter screen is installed, closed on top by a protective frame, characterized in that the filter screen is a sleeve made of elastic filter material with a given filtration fineness, the perimeter of the filter screen in cross-section is less than the perimeter of the supporting frame by 2-5%, while the filter screen is stretched in a direction perpendicular to the longitudinal axis of the filter element.

2. A filter element according to paragraph 1, characterized in that the supporting frame is made of an elastic porous material.

3. A filter element according to paragraph 1, characterized in that the supporting frame is made of an elastic mesh material.

4. A filter element according to paragraph 1, characterized in that the filter material with a given filtration fineness has hydrophobic and oleophobic properties.

5. A filter element according to paragraph 1, characterized in that the filter material with a given filtration fineness has corrosion resistance.

6. A filter element according to paragraph 1, characterized in that the filter material with a given filtration fineness has heat resistance up to 600 °C.

7. A filter comprising end pieces rigidly connected to each other and at least one filter element which includes a permeable supporting frame made of elastic material that is hollow inside and closed in cross-section, on top of which a filter screen is installed, closed on top by a protective frame, characterized in that the filter screen is a sleeve made of elastic filter material with a given filtration fineness, the perimeter of the filter screen in cross-section is less than the perimeter of the supporting frame by 2-5%, wherein the filter screen is stretched in a direction perpendicular to the longitudinal axis of the filter element.

8. The filter according to paragraph 7, characterized in that the supporting frame of the filter element is made of an elastic porous material.

9. The filter according to paragraph 7, characterized in that the supporting frame of the filter element is made of an elastic mesh material.

10. The filter according to paragraph 7, characterized in that the filter material with a given filtration fineness of the filter element has hydrophobic and oleophobic properties.

11. The filter according to paragraph 7, characterized in that the filter material with a given filtration fineness of the filter element has corrosion resistance.

12. The filter according to paragraph 7, characterized in that the filter material with a given filtration fineness of the filter element has heat resistance up to 600 °C.

Images