GB2174187A

GB2174187A - A plate heat exchanger

Info

Publication number: GB2174187A
Application number: GB08510704A
Authority: GB
Inventors: Helmut Fischer
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-04-26
Filing date: 1985-04-26
Publication date: 1986-10-29
Also published as: FR2581449A1; GB8510704D0; GB2174187B; FR2581449B1

Abstract

A plate heat exchanger has numerous heat exchange plates, preferably stamped out of sheet metal, which are clamped between two solid pressure plates. The exchange plates have a flow zone (1) surrounded by an edge seal (4) and also comprises openings (2). The exchange plates also have openings (3), outside the flow zone, for the second medium and are surrounded by an annular seal (6) and are separated from the flow zone by a second seal (11). At least one of the seals (6, 11) is embedded in upwardly tapering beads (10). The adjacent plate below the beads has beads (7, 8) parallel thereto and widening upwardly, and the sides of the last-mentioned beads have a number of tapering raised portions (9) which bear on the adjacent plate at or near the lower edges of the beads (10). <IMAGE>

Description

SPECIFICATION A plate heat exchanger The invention relates to a dismountable plate heat exchanger comprising a stack of adjacent heat exchange plates, preferably stamped out of sheet metal and having a flow zone surrounded by an edge seal and also having openings for two media. The flow space for one medium also comprises the openings for that medium, whereas the openings for the second medium are outside the flow space and are surrounded by seals so that the two media are separated by double seals.

In the case of the adjacent plate, the space under the double seals belongs to the flow space for the second medium. The object of the invention is to devise a particularly rigid construction for this region, which critically affects the compressive strength of the heat exchanger.

The seals of the heat exchange plates are embedded in grooves to prevent them bending sideways and in order to obtain the surface pressure needed for high operating pressures. The seals are usually made of resilient material. Near the edge of the plates it is relatively easy to obtain the necessary pressure, since here the sheet metal and seal bear on one another in an alternating sequence and the pressures are fully transmitted from one plate to the next.

However, at those places where the opening is connected to the flow zone, the seal of the neighbouring plate presses against a cavity, and thus may buckle. Since heat exchange plates have to be made of very thin sheet metal, attempts are made to shape the plate so as to prevent buckling in this region. This is done by providing reinforcing knobs along the sealing groove to maintain the spaces between plates. This construction brings an improvement but is of limited effectiveness. Although the sealing bead, usually U-shaped for receiving the seal, has considerable rigidity owing to its shape, sagging occurs between it and the neighbouring reinforcing knobs, and frequently causes leaks both in the resilient region and as a result of permanent deformation.Attempts have therefore been made to replace the knobs by recesses extending substantially perpendicular to the sealing beads and opening into them. This improves the transmission of force from the reinforcing area to the bead, but weakens the bead itself, since it is interrupted at the mouth of the recesses. The interruption also enables the seal to bend sideways at this place, which disadvantageously affects the required surface pressure on the seal.

To avoid the aforementioned disadvantages in the case of heat exchange plates used at high operating pressures, the next idea was to weld reinforcing elements in the flow space of the plates under the sealing groove of the adjacent plate. These spacer elements comprise corrugated sheet-metal strips about the same width as the seal and lying under the sealing bead and welded to the neighbouring plate. This embodiment has the disadvantage of being much more expensive and is also unreliable, owing to the numerous welds.

Large heat exchange plates of this kind often have more than a hundred such welds, which may impair the metal structure.

In the invention, the heat exchange plates are produced by stamping only, and the sealing groove near the openings and the flow space of the neighbouring plates is specially shaped so as fully to satisfy the compressive strength requirements. The groove sealing the opening is shaped so as to taper upwards. A trapezoidal rubber seal, with its narrower side upwards, is embedded in the groove. Below the sealing bead, the adjacent plate is likewise formed with a groove, which however widens upwardly, thus maintaining the gap needed for the medium to flow between adjacent plates.

The sides of the bead have a number of inwardly facing convex portions dimensioned so that they touch the adjacent plates at or slightly below the edges of the sealing bead.

In this manner the sealing bead is supported directly.

A similar construction is given to each portion of the boundary of the flow space facing the opening. The construction of the rest of the edge bead and its seal do not form part of the invention.

Figure 1 is a view in elevation of heat exchange plate constructed according to the invention; Figure 2 is a section through a sealing portion of three superposed plates near the openings; Figure 3 is a plan view of a portion of the topmost of the three plates; Figure 4 shows a corresponding portion with staggered reinforcing elements; Figure 5 shows a cross-section as a variant to Fig. 2 and Figure 6 is a plan view of part of the topmost of the three plates.

Fig. 1 shows a heat exchange plate having a flow zone 1, openings 2 inside the zone and openings 3 outside the zone. The flow zone is surrounded by a seal 4 having a portion 5 in which a seal 11 is embedded and which forms part of a double seal against openings 3, which in turn is surrounded by a seal 6. A bead 7 is formed symmetrically with seal portion 5, relative to the longitudinal axis of the plate. Bead 8 is symmetrical with the portion of seal 6 facing the flow zone. Both beads have convex portions 9.

Fig. 2 is a section through a sealing portion of three superposed plates along line AB. The central plate has upwardly conically tapering beads 10 for receiving seals 6 and 11, the underside of beads 10 being adjacent convex portions 9 of the neighbouring plate.

Fig. 3 is a plan view of part of a plate 7, in which the convex portions 9 are opposite one another.

Fig. 4 shows a variant portion thereof, in which the convex portions 9 are offset from one another.

Fig. 5 shows a section through a variant, comprising a sealing portion of three superposed plates. In Fig. 5, beads 7 and 8 are each formed with two roof-like raised portions 12, in which the convex portions 9 are incorporated.

Fig. 6 is a plan view of part of groove 7, which is made up of raised portions 12 and convex portions 9 incorporated therein.

The exchange plates can be clamped between two solid pressure plates.

Claims

1. A plate heat exchanger having a plurality of heat exchange plates clamped, in use, between two solid pressure plates, the exchange plates having a flow zone surrounded by an edge seal and with openings, the exchange plates also having openings outside the flow zone for a second medium and surrounded by an annular seal and separated from the flow zone by a second seal, characterised in that at least one of the seals is embedded in upwardly tapering beads and the adjacent plate has beads parallel to and underneath the first mentioned beads and widening upwardly and the sides of the latter beads have a number of tapering raised portions resting on the adjacent plate at or near the lower edge of the beads.

2. A heat exchanger according to claim 1 wherein the beads in the flow zone each comprise two parallel V-shaped beads projecting from the plane of the plate, the parallel beads beig connected by a strip in the plane of the plate.

3. A heat exchanger according to claims 1 and 2, wherein the raised portions in the parallel sides of the beads are offset from one another.

4. A heat exchanger substantially as herein described with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: Claims 1 above have been deletedor texturaily amended.

New or textually amended claims have been filed as follows:

1. A plate heat exchangerhaving a plurality of heat exchange plates clamped, in use, between two solid pressure plates, the exchange plates having a flow zone with openings, said flow zone being surrounded by a first seal, the exchange plates also having openings outside the flow zone for a second medium and surrounded by an annular second seal and sepated from the flow zone by a third seal, characterised in that at least one of the second and third seals is embedded in upwardly tapering beads and the adjacent plate has beads parallel to and underneath the first mentioned beads and widening upwardly, and the sides of the latter beads have a numberof tapering raised portions resting on the lower edges of the beads.