RU2569465C1 - Safety membrane device - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: safety membrane device contains buckling membrane secured between two clamping flanges. At side of concave part of the bucking membrane against its top the cutting device is secured by non-working sides. This device has four flat knives and two additional knives. The knives are uniformly distributed along the circle around the central axis of the buckling membrane. Each knife is made in form of right triangle, largest leg has cutting edge of sawtooth configuration. Another leg has two rectangular shoulders for securing in the ring groove of the bottom clamping flange, and in corresponding slot of the lock pressing ring. In the said pressing ring for this slots are made according to number of knives, and as well as securing holes on same axis with securing holes of top and bottom clamping flanges.

EFFECT: assurance of nonscatterable activation of the device due to increased strength of engagement of cut lobes of the buckling membrane along line of clamp of the ring part.

7 dwg

Description

Technical field

The invention relates to safety valves, providing the necessary weight loss of the vapor-gas mixture at a certain pressure, and is intended to protect objects of technological equipment, vessels and pipelines from dangerous overloads by excessive and (or) vacuum pressure created by the working environment, and is installed, in particular, in protection systems for steam generators of nuclear power plants.

State of the art

The membrane safety device (MPU) consists of a bursting or popping safety membrane and its mounting unit along the edge ring section assembly with other elements. The safety membrane is destroyed at a given pressure and the necessary flow area is freed for the protected vessel (pipe) to communicate with the discharge system. MPU with a bursting membrane, flat or dome-shaped, are used on liquid and gaseous media and work on bursting under pressure acting on its surface. MPUs with a popping dome-shaped membrane work for buckling (cotton) under pressure acting on a convex surface. Losing stability, the membrane is cut on knife blades or torn along a previously weakened section. To protect the vessels working under pressure, MPUs are widely used, the principle of which is based on cutting the membrane with a fixed knife at the time of its maximum allowable deflection.

It is known that curved safety rupture disks of reverse action have a recess having a recess representing a line of weakening or a tear line on one outer surface of a curved disk. The lines of weakening or lines of discontinuity, as a rule, are intersecting cuts or a circumferential recess, which is a line of weakening on the concave surface of the disk, determine the boundaries of the zone of the disk, which breaks when reversed. The safety rupture disk with the machined rupture line contains a curved part and a bounding flange zone surrounding the curved part (RU 2507428 C2, 6 IPC F16K 17/16, published December 20, 2014, Fike Corporation, (US) [1]. it forms four petals that intersect outward when the disk is reversed, which also prevents the separation of the petals into parts.Circular incision lines or weakening lines are preferred in cases of use at low pressure due to a larger hole, about which ruptures upon rupture of a disk along an arcuate notch line, compared with a disk with intersecting notches.

Known destructible membrane (RU 2317462 C1, 6 IPC F16K 17/16, publ. 02.20.2008) [2] is made with a thickening in the central part. A groove in the form of an incomplete ring with rectilinear end sections forming a flexible radial jumper in the peripheral part of the disk is made along the perimeter of the thickening. At a radius of passage of the annular groove, at least one flexible radial jumper formed by rectilinear end sections is additionally made. Jumpers are distributed evenly. Additional straight grooves connect the annular grooves to each other through the center of the disk. The diameter and thickness of the disk in its central part and in places of thinning along the bottoms of the annular and additional grooves are selected from the condition of providing a given pressure for the destruction of the membrane and the throughput of the hole formed. At the same time, when the membrane is destroyed, the formation of several identical parts, each of which bends along its radial bridge and hangs on it without forming fragments.

The presence of annular and additional rectilinear grooves for streamlining the process of membrane destruction does not ensure the reliability of shatter-free opening of the membrane due to the heterogeneity of the microstructure of the metal, affecting the stress concentration in the grooves.

To protect vessels operating under pressure, membrane-based safety devices are widely used, the principle of operation of which is based on cutting the membrane with a fixed knife at the time of its maximum permissible deflection (US 4394926, 3 IPC F16K 17/40, publ. 26.07.1983, BS & BSafety Systems , Inc, US) [3]. The device contains four triangular knife segments located at right angles to each other, having pointed edges. After the device is activated, the separated part of the membrane under the action of inertial forces is carried away by the flow of the working medium into the system, which in some cases can lead to failure of the protected equipment.

Known membrane safety device (RU 1601447 A1, 5 IPC F16K 17/16, publ. 23.10. 1990) [4], which increases the reliability of operation due to the complete opening of the membrane. A domed membrane is sandwiched between the flanges. A destructive element is fixed to the flange from the concave side of the membrane, made in the form of four flat knives intersecting along the longitudinal axis. The peripheral points of the knives are located in the plane of the connector on the circumference of the flange bore. The cutting edges of the knives are made in the form of sides and a smaller base of the trapezoid. The intersection point of the peripheral side of the trapezoid with a smaller base is located between the plane of the connector and the surface of the reverse deflection of the membrane. The intersection point of the other side of the trapezoid with its smaller base is located in the plane of the connector. The peripheral sides of the trapezoid provide cutting of the peripheral part, however, with the formation of fragments, which is unacceptable in devices with a high degree of protection.

The problem of eliminating the formation of fragments during the destruction of the membrane was solved in the products of BS&B Safety Systems, Inc. US by rupture of the membrane along a pre-weakened section using a retaining hinge located outside the zone of weakened section (US 5167337, 6 IPC F16K 17/16, 12/01/1992) BS & BSafety Systems, Inc, US) [5], which also does not provide reliability membrane-free opening due to heterogeneity of the microstructure of the metal, which occurs even with laser and electrochemical processing of attenuation lines.

The closest in technical essence to the claimed invention is a safety membrane device of REMBE GmbH SAFETY + CONTROL: (Safety membranes in comparison. Design with a knife. Rembe types - BT-UKB, IG-UKB-LS, Table 1 (The Chemical Journal, June July 2011)) [6], taken as a prototype of the present invention, which contains a clapping membrane, an annular part sandwiched between two, upper and lower clamping flanges, a cross-shaped cutting tool with four flat knives with cutting edges that are inclined from the central axis, located opposite the top flapping membrane in the region, providing touch membrane at its estimated deflection under the influence of pressure on the convex surface of the membrane, the blade knives are rigidly fixed welded on the inner wall of the upper clamping flange. When the pressure allowed for a given popping membrane is increased, the membrane, losing stability, collapses and cuts with knives into four petals, which, due to the high-pressure gas stream, break off along the edge of the clamp due to gas turbulence, and fragments can damage, clog the pipeline and even ignite the medium, especially in places of bending of the pipeline.

The prototype device provides a complete opening of the membrane, but with the formation of fragments.

The design of the MPU (Laboratory of Membrane Safety Devices Laboratory, Moscow, LLC, similar to the one described above). Popping membranes (MX). Catalog. Main characteristics) [7] has an accuracy of ± 5-10% in a working gas environment.

Tests of this design, carried out by the authors of the present invention, showed the formation of fragments when the four knives cut the membrane when it is triggered, which is unacceptable in apparatuses and pipelines with a high degree of safety. In addition, the known PMU with knives are disposable and, after the clapping membrane is triggered, it is disposed of due to the presence of a welded joint between the non-working sides of the knives and the inner wall of the clamping flange.

Disclosure of invention

The technical result of the present invention is to provide chipless operation of the PMD by increasing the adhesion strength of the cut petals of the popping membrane along the clamp line of the annular part. Cutting the popping membrane when it is deflected by at least six petals leads to a decrease in the curvature of the adhesion sections of the petals along the clamp line of the annular part of the membrane and, as a consequence, to a decrease in stress and an increase in adhesion strength. The implementation of the cutting edge of the sawtooth knives increases the pressure of cutting the popping membrane into the petals when it is triggered.

An additional technical result is the possibility of reusable use of clamping flanges when replacing knives by replacing the welded joint of the knives with a collapsible mount, which ensures the safety for future use of part of the membrane unit after the membrane is triggered.

The specified technical result is achieved in that the safety membrane device comprises a popping membrane fixed by an annular part with fasteners between two clamping flanges, on the side of the concave part of the popping membrane opposite its top at a deflection distance when it is triggered by the calculated pressure, the cutting is fixed to the clamping flange by non-working sides means containing four flat knives evenly spaced around the circumference around the central axis of the clapping membrane.

According to the invention, the cutting means further comprises at least two knives, each knife is made in the shape of a right-angled triangle, the larger leg of which has a sawtooth-shaped cutting edge, and the other leg is provided with two rectangular projections for fastening in the annular groove of the lower clamping flange and in the corresponding groove a locking clamping ring in which grooves are made according to the number of knives and mounting holes on the same axis as the mounting holes of the upper and lower clamping flanges.

As the experiments conducted by the authors of the present invention showed, the implementation of a cutting tool with six knives with a sawtooth-shaped cutting edge provides, when the pressure of the popping membrane is activated, it is effectively cut into six petals with a deviation from the central axis and holding them along the clamp line of the annular part of the membrane without creating fragments. An increase in the number of knives will increase the reliability of the shatterproof membrane.

Brief Description of the Drawings

The present invention is illustrated by the figures of the drawings and table.

FIG. 1 is a drawing of the inventive safety membrane device, a longitudinal section.

FIG. 2 - knife, front view.

FIG. 3 is a diagram of an arrangement of knives in a safety membrane device, top view.

FIG. 4 - circlip for fastening knives, top view.

FIG. 5 - circlip for fastening knives, side view.

FIG. 6 is a photograph of a shatterproof clapping membrane after triggering according to the claimed invention with six knives with a sawtooth cutting edge, tested on the stand "Automatic system for the diagnosis of membranes" in the pressure range of 0.2-5 MPa.

FIG. 7 is a photograph of a fragmentation clapping membrane of a prototype with four knives tested on the stand "Automatic system for the diagnosis of membranes" in the pressure range of 0.2-5 MPa.

The implementation of the invention

The safety membrane device (PMU) of FIG. 1 contains a popping membrane 1 made of sheet metal. The annular part 2 of the popping membrane 1 is circumferentially clamped by fasteners (not shown in the drawing) between the upper clamping flange 3 and the lower clamping flange 4, in which the mounting holes 5 and 6 are made.

An annular groove 7 is made in the lower clamping flange 4. Opposite the concave part of the popping membrane 1, at the distance of the deflection of the membrane when it is triggered under the influence of the calculated critical pressure, there is a cutting tool containing at least six knives 8, 9, 10, 11, 12, 13 located radially around a central axis (FIG. 3). Each knife (Fig. 2) is made in the form of a rectangular triangle, the larger leg of which has a sawtooth-shaped cutting edge, and the other leg is equipped with two rectangular protrusions (14, 15) for fastening in the annular groove 7 of the lower clamping flange 4 and in the corresponding groove of the locking clamp ring 16 (Fig. 1, 4), in which the grooves 17 are made according to the number of knives and the mounting holes 18 are on the same axis as the mounting holes 5, 6 in the upper and lower clamping flanges 3, 4 (Fig. 1). When assembling the PMU, the knife with the protrusion 14 is inserted into the groove 7, and with the protrusion 15 into the groove 17 of the retaining pressure ring 17 and so on for each knife. With an increase in the pressure acceptable for a given popping membrane, the membrane, losing stability under the influence of a gas-dynamic jet, collapses and is effectively cut by knives 8, 9, 10, 11, 12, 13 into six petals (Fig. 6), which deviate from the central axis of the PMP and are held along the edge of the clamp of the annular part 2 of the popping membrane 1 by reducing the curvature of the adhesion sections of the base of the segment of each petal, which leads to a decrease in the concentration of tear-off stress on the base of the petal and an increase in its adhesion strength inii clamp.

The flapping membrane 1 is made on the installation developed by the authors (RU 2353456, 6 IPC B21D 22/10. Published on 04/27/2009) [8]. The rod with the load is raised with a clamp relative to the plane of the strip billet to a height less than the specified height of the membrane dome. Under the influence of compressed air, the membrane dome is in contact with the contact disk and raises the load to a predetermined height, determined by the optoelectronic position sensor, which controls the threshold element. By changing the load value and the lifting height of the membrane dome under the influence of the load, a membrane with the required critical pressure value is formed.

The used clapping membrane has the following main characteristics:

accuracy of operation 2-4% response range 1-50 kg / cm size range 25-350 mm

As a result of laboratory tests of the proposed PMU, the cutting edges of the knives withstand 2-3 operations, and their replacement is possible due to the collapsible design of the membrane assembly, which provides reusable use of clamping discs and leads to savings in the cost of operating the PMU. Technical documentation has been prepared, the invention is ready for use.

Information sources

1. RU 2507428 C2, 6 IPC F16K 17/16, publ. 12.20.2014, Fike Corporation, (US).

2. RU 2317462 C1, 6 IPC F16K 17/16, publ. 02/20/2008.

3. US 4394926, 3 IPC F16K 17/40, publ. 07/26/1983, BS & BSafety Systems, Inc, US.

4. RU 1601447 A1, 5 IPC F16K 17/16, publ. 10/23/1990.

5. US 5167337.6 IPC F16K 17/16, 12/01/1992, BS & BSafety Systems, Inc, US.

6. Safety membranes in comparison. Flapping and universal membranes. Design with knife, type BT-UKB, IG-UKB-LS, Tab. 1. Rembe GmbH SAFETY + CONTROL. The Chemical Journal, June-July 2011 - prototype.

7. Clapping membranes (MX). Catalog. Main characteristics. Laboratory Membrane Safety Devices LLC, Moscow.

8. RU 2353456, 6 IPC B21D 22/10, publ. 04/27/2009.

Claims (1)

A safety membrane device containing a clapping membrane fixed by an annular part with fasteners between two clamping flanges, on the side of the concave part of the clapping membrane opposite to its top at a deflection distance when it is triggered under the influence of design pressure, a cutting tool containing four flat knives is fixed to the clamping flange by non-working sides evenly spaced around the circumference around the central axis of the clapping membrane, characterized in that the cutting means contains additional At least two knives, each knife is made in the form of a rectangular triangle, the larger leg of which has a sawtooth-shaped cutting edge, and the other leg is equipped with two rectangular protrusions for fastening in the annular groove of the lower clamping flange and in the corresponding groove of the retaining pressure ring, which for this purpose, grooves are made according to the number of knives and mounting holes on the same axis as the mounting holes of the upper and lower clamping flanges.

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