RU240396U1 - Filter for oil-containing liquids - Google Patents

Abstract

This utility model pertains to the filtration of oil-containing liquids in production and process lines. It concerns filter vessels operating under pressures of up to 4.0 MPa and temperatures ranging from minus 40°C to plus 60°C and designed to remove mechanical impurities from oil, oil-gas-water mixtures, and petroleum products. The technical challenge is to ensure reliable sealing of the filter for oil-containing liquids without the need for high lid tightening force, as well as to simplify maintenance and provide quick access to the filter element. The technical result consists of increased seal reliability. The filter for oil-containing liquids comprises a metal housing with inlet and outlet pipes and a diaphragm for accommodating a removable filter element, as well as a lid connected to the housing using studs and nuts evenly spaced around the perimeter. A sealing device, a V-shaped elastic cuff made of nitrile butadiene rubber, is installed between the mating end surfaces of the housing and cover. It is located in an annular groove on one of the end surfaces. In its initial state, the cuff has a gap of 0.5-1.0 mm between the outer surface and the mating surface of the other part. Upon contact with oil, an oil-gas-water mixture, or petroleum products, the cuff swells, increasing in size by 10-30%, filling the gap and sealing the housing and cover.

Description

This utility model pertains to the filtration of oil-containing liquids in production and process lines. It concerns filter vessels operating under pressures of up to 4.0 MPa and temperatures ranging from -40°C to +60°C and is designed to remove mechanical impurities from oil, oil-gas-water mixtures, and petroleum products. The filter requires easy disassembly for replacement of the replaceable filter element and reliable sealing during operation under pressure.

A filter patented by RU 2323031 C1 uses a housing cover secured by an elastic shoulder and a collar (rolling). The cover is equipped with a cover plate and a reinforcement, and sealing is achieved by a gasket installed between them. Sealing depends on the rolling and pressure on the gasket, which complicates assembly and eliminates repeated disassembly. This method does not require a swelling seal.

Utility model RU 192999 U1 (selected as the prototype) is a disassemblable oil filter with a threaded steel housing and cover. Sealing is achieved with a gasket. The base has drainage holes and an anti-drain valve, and the filter element is pressed against the cover by a spring. A similar device, patent RU 2482293 C2, uses a threaded connection between the base and cover and a rubber ring for sealing. A disadvantage of these devices is the need for significant force to tighten and remove the housing to remove the cover.

Applications EP 1524020 A1 and US 20050077231 A1 describe a filter with a replaceable cartridge and a complex-shaped seal equipped with a petal that is pressed against the supporting surface first mechanically and then by oil pressure. The seal does not swell: sealing is ensured by the shape of the seal and hydraulic pressure. The design is complicated by a double rubber element and is intended for spinon filters, not vessels with quick-release lids.

Patent EP 0869839 B1 describes a filter with a housing and a removable lid, between which a rubber gasket is located. When the lid is tightened, the gasket compresses, ensuring a tight seal. Achieving a tight seal requires significant mechanical force and a special flange; the seal is achieved by a static gasket.

The listed alternatives are characterized by the connection of the lid and body using threads, rolled-on fittings, or flanges, and the use of traditional seals. Sealing is achieved only by clamping force and precise adjustment, which complicates operation. None of the alternatives uses a sealing cuff that swells upon contact with oil-containing liquids, as in the proposed model.

The technical challenge is to ensure reliable sealing of a filter for oil-containing liquids at pressures up to 4.0 MPa and temperatures ranging from -40°C to +60°C without requiring high tightening force on the cap, as well as to simplify maintenance and provide quick access to the filter element. The technical result is increased seal reliability.

The technical result is achieved in a filter for oil-containing liquids (hereinafter also referred to as the "filter"), comprising a metal housing with inlet and outlet ports and a diaphragm for accommodating a removable filter element, as well as a cover connected to the housing by studs and nuts evenly spaced around the perimeter. A sealing device in the form of an elastic cuff with a V-shaped cross-section made of nitrile butadiene rubber is installed between the mating end surfaces of the housing and cover and is positioned in an annular groove of one of the end surfaces. In its initial state, the cuff has a gap of 0.5-1.0 mm between the outer surface and the mating surface of the other component. Upon contact with oil, an oil-gas-water mixture, or petroleum products, the cuff swells, increasing in size by 10-30%, filling the gap and providing a seal between the housing and cover. When tightening the nuts, the cover moves relative to the housing, with a travel limit set by the threaded stud connections. This prevents overstretching of the seal and provides the necessary clearance for swelling. A removable filter element is installed on the diaphragm inside the housing and locked by the cover, simplifying element replacement and filter maintenance. Depending on the design, the filter's nominal bore can be DN50, DN100, DN150, or DN200, and connections are made via welded or flanged connections.

Brief description of the drawings

Fig. 1 - general view of the filter;

Fig. 2 - cuff;

Fig. 3 - cross-section of the cuff.

The filter with a quick-release cover 1 has a metal housing 2 of cylindrical shape with inlet and outlet pipes 3, 4, with a plug 14. The housing 2 is made from a section of pipe, for example, 273 mm in diameter and a wall thickness of 12 mm, approximately 345 mm long. A pipe 5 of a smaller diameter is welded to the lower part of the housing 2, which serves to drain the oil-containing liquid, for example, during filter maintenance. Flanges 6, 7 are welded to the housing 1 for connection to pipelines. A diaphragm 8 is located in the housing 1, to which a removable filter element 9 is attached. The diaphragm 8 is an internal support partition that serves as a support for the removable filter element 9, fixes it in place, sets the flow direction, ensures uniform pressure distribution inside the housing and stable operation of the filter. The diaphragm 8 may have a mesh base or an annular support for the plate pack. The filter element 9 is made of corrosion-resistant materials, such as stainless steel, and is mounted on the diaphragm 8 with support on the belt; from above, the filter element 9 is fixed by the cover 1, for example, through the stop 10.

Cover 1 is made in the form of a disk corresponding to the diameter of housing 2. In the basic version, it is pressed against housing 2 using studs 11 M30×160 mm and nuts 12 AM30-6H; for auxiliary flanges 7, studs M16×80 mm and nuts AM16-6H are used. An annular groove is made on the end surface of cover 1 for accommodating elastic cuff 13. Cuff 13 has a V-shaped cross-section, is made of butadiene-nitrile rubber in accordance with GOST 14896-84, corresponds to rubber groups 1-3 according to GOST 18829-73 and has a hardness of 40-95 units on the Shore A scale. The initial gap between cuff 13 and the mating surface of housing 2 is 0.5-1 mm. Upon contact with oil, cuff 13 swells by 10-30% and fills this gap, ensuring a tight connection. Unlike traditional rubber rings, sealing is achieved not only by the pressing force, but also by increasing the volume of cuff 13, therefore manual force is sufficient to tighten studs 11.

In addition to body 2, cover 1, and cuff 13, the design includes gaskets for sealing flange connections, as well as nipple 15 with an M20×1.5 nut for connecting drainage or measuring instruments. Removable filter element 9 is attached to diaphragm 8 and pressed against cover 1, allowing for easy replacement, like a cartridge element, during maintenance.

The filter operates as follows. Oil-containing liquid enters filter housing 2 under pressure through inlet pipe 3, passes through removable filter element 9, on the surface and in the volume of which mechanical impurities are retained, and purified liquid is discharged through outlet pipe 4. The tightness of the connection between housing 2 and cover 1 is ensured by a sealing cuff 13 of a V-shaped cross-section: when tightening the nuts of studs 11, cuff 13 is partially deformed, and upon contact with the working medium, it swells, tightly filling the gap between cover 1 and housing 2. To service the filter, the fasteners are loosened, quick-release cover 1 is removed, filter element 9 is removed and replaced, after which cover 1 is installed in place and the nuts are retightened.

During structural testing, the pressure was gradually increased to a test value equal to 0.25 times the design value and maintained for at least ten minutes. During hydraulic testing, the pressure was increased to 5 MPa; no leaks were detected through the connection between cover 1 and body 2. Multiple loading and unloading cycles did not result in failure of seal 13; the seal remained sealed even when studs 11 were tightened manually. These results confirm that sealing seal 13 made of NBR provides a reliable seal without the need for high clamping force and is resistant to repeated pressure cycles. Even without taking into account the swelling of the elastic material of seal 13, the V-shaped cross-section ensures the stated technical result—a reliable seal with reduced tightening force. The V-shaped profile forms two sealing edges and an internal cavity. When tightening the cover, the seal's edges act like a wedge: a slight axial movement of the cover causes significant radial compression of the edges against the mating surfaces of the housing and cover. During filter operation, internal medium pressure acts additionally in the "V" cavity and expands the profile, converting the medium pressure into increased contact pressure at the edges. Thus, the V-shaped geometry provides: a self-priming seal due to the wedge effect and the action of medium pressure; two independent contact lines (double barrier) and an increased leakage path; compensation for manufacturing tolerances and slight displacements of the cover relative to the housing. Therefore, even in the absence of swelling of the seal material, the V-shaped profile itself allows for the required seal to be achieved with less tightening force on the studs compared to a traditional flat or rectangular sealing ring; swelling increases the sealing reserve.

The described solution simplifies filter assembly and disassembly, expanding the operating conditions. This is achieved by using an elastic seal 13 made of nitrile butadiene rubber (NBR) with a V-shaped cross-section. This seal is capable of swelling by 10-30% in oil-containing environments and is installed with an initial gap between the mating end surfaces of the cover and housing. Upon contact with the working fluid, the seal expands and fills the gap, creating a tight seal even with minimal tightening force. This improves the reliability of the filter seal.

Claims (4)

1. A filter for an oil-containing liquid, comprising a housing with inlet and outlet pipes, a removable filter element placed inside the housing on a diaphragm, and a cover connected to the housing by means of studs with nuts evenly spaced around the perimeter; a sealing ring is installed between the mating end surfaces of the housing and the cover, characterized in that the sealing ring is made in the form of an elastic cuff of a V-shaped cross-section, placed in an annular groove with an initial gap between the cuff and the mating surfaces of the cover and the housing, wherein the cuff is designed with the possibility of swelling upon contact with an oil-containing liquid. 2. The filter according to item 1, characterized in that the cuff is made of butadiene-nitrile rubber. 3. The filter according to paragraph 1, characterized in that the initial gap between the cuff and the mating planes of the cover and the housing is 0.5-1.0 mm. 4. The filter according to paragraph 1, characterized in that when the nuts are tightened, the cover moves relative to the housing with a travel limitation set by the threaded connections of the studs with the nuts.