GB2218795A

GB2218795A - Sealing of plates in a heat exchanger

Info

Publication number: GB2218795A
Application number: GB8910862A
Authority: GB
Inventors: Walter Kawe; Harald Schomburg; Holm Dittmar; Bodo Hille; Ernst Schmidt; Herbert Siebenhuener
Original assignee: Nagema VEB
Current assignee: Nagema VEB
Priority date: 1988-05-18
Filing date: 1989-05-11
Publication date: 1989-11-22
Anticipated expiration: 2009-05-11
Also published as: SE8901694D0; GB8910862D0; SE8901694L; DD271947A1; GB2218795B; DK164489D0; DK166518B1; SE467638B; DK164489A; DE3910070A1

Description

a -1 SEALING OF PLATES IN A HEAT EXCHANGE 2 2? 18 7 9 5 The present

invention relates to a heat exchanger and has particular reference to the sealing of plates in a heat exchanger.

Plate heat exchangers are known, in which seals laid in sealing grooves of heat exchanger plates are glued in place by means of a suitable adhesive substance so as to provide protection against droppingout. The cross-section of the groove is preferably trap ezi uin- shaped and the side surfaces have a positive opening angle. The shape of the seal is matched to the groove, so that the side surfaces lie against the walls of the groove when the seal is inserted.

These heat exchangers have the disadvantage that the sealing material is often difficult to glue to the plate and that considerable effort is necessary for exchange of the rapidly wearing glued-in seal. For this reason, attempts have been made to obviate gluing of the seal into the groove.

Thus, in DE 86 63 49 there is described a plate with a sealing groove which has a trapezi um- shaped cross--section with negative opening angle, i.e. a dovetail-shaped cross-section. A trap ezi um-shap ed seal matched to the dovetail shape was placed in the groove. Thereby, dropping of the seal out of the groove was prevented and gluing was no longer necessary. The disadvantage of this arrangement consists in the complicated production of the groove shape in the thin-walled heat exchanger plate and in maintaining dimensional constancy over the entire groove length. A further disadvantage consists in that the pressing of the seal into the dovetail groove is very difficult. Thus, it was proposed in WO 87 01 189 that the groove should not be dovetail shaped over the entire circumference, but should have a dovetail-shaped cross- section only at discrete locations. Since the f! 2 - seal is of corresponding shape, clamping of the seal in the groove takes place only at these locations. Parallelly thereto, in WO 84 04 809 there was proposed a seal with hollow spaces which, on fitting of the seal into the groove as well as in the case of high contact pressures in the operational state, permit deviation of the sealing material. With these two solutions the seals could be assembled more easily, but the increased effort in manufacture of the dovetail groove remained.

Also known are solutions in which gluing of the seal is not necessary and a dovetail groove is not needed. Thus, according to GB 2 069 680, the seal is retained in a trapezium-shaped sealing groove having a positive opening angle in that press-button spigots are provided on the seal and locate in holes in the base of the groove.

In addition, according to DE 8 701 365 the sealing groove may have beads formed on the side surfaces over the entire length of the groove or only at discrete locations. In this case, the seal has congruent depressions so that the connection between seal and heat exchanger plate is effected through detenting after pressing of the seal into the groove. Although these various methods of connection represent alternatives to gluing of the seal, they require increased production effort in manufactre of the groove. This leads to an appreciable increase in the manufacturing costs for the heat exchanger plates.

It would thus be desirable to provide a means of sealing heat exchanger plates one against the other without a gluing of the seals and without additional functional elements in the sealing grooves, wherein the effort for the manufacture of the sealing groove should Z1 f _1 preferably not be greater than the effort required in the traditional gluing process. The seal should preferably be so firmly inserted without adhesive substance into the groove that it does not detach during transport and manipulation and at the same time be so arrested that a secure sealing is ensured in the plate heat exchanger after assembly.

According to the present invention there is provided a heat exchanger comprising a plurality of heat exchanger plates held tightly together in frame means and a plurality of sealing elements arranged in circumferential grooves in the plates and sealing the plates relative to each other, each sealing element being provided at two mutually opposite side surfaces thereof with deformable protrusions disposed in the respective groove and the width of the sealing element between the extremities of the protrusions in undeformed state being greater than the minimum width of the groove.

In a preferred embodiment, the heat exchanger comprises a plurality of heat exchanger plates which are tightened together in a frame and sealed off one from the other by the sealing elements located in their circumferential grooves, the sealing grooves being rectangular or trapezium-shaped in cross-section with slightly positive or negative opening angle. Each sealing element can be constructed with substantially parallel side surfaces and has preferably wedge-shaped protrusions on the lower half of its side surfaces. The sealing element has a maximum width across the protrusions which is greater than the width of the groove. Through the arrangement of such wedgeshaped protrusions at the lower half of the side surfaces, protrusions are compressed during the pressing of the sealing element into the groove, i.e. the protrusion is laid against the side surface of the element. Due to the tendency to resume the original shape, the protrusions, after detenting in the groove seek to erect themselves again and lead to clamping of the element in the groove. It is thus necessary that the sealing element has a maximum width greater than the width of the groove. The width across the protrusions need exceed the width of the groove by only a small amount. The clamping effect in the groove is achievable with, for example, a rectangular or a trapezoidal cross-section, with slightly positive or negative opening angle, of the groove. A departure from parallelism of the side surfaces of substantially + 2 is permissible for, for example, a rectangular cross- section of the groove. The sealing element can be constructed with parallelly extending side surfaces. The tolerance between element and groove can be such that an introduction of the element into the groove is possible nearly free of gap and without great effort. The protrusions can extend around the entire circumference of the sealing element or they can be arranged at the circumference only at certain places, thus in an interrupted sequence.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a plan view of a heat exchanger plate embodying the invention; is a-cross-section through the heat exchanger plate with inserted seal; are cross-sectional views of different seal shapes; Fi g. 2 Figs. 3 and 4 1.

11 Fi 9. 6 Fi g. 7 Fig. 5 is a cross-section of one shape of groove for receiving_ such a seal; is a cross-section of another shape of groove, with inserted seal; and is a view of a seal with protrusions arranged only at discrete locations.

Referring now'to the drawings, there is shown in Fig. 1 a heat exchanger plate in which the heat exchanger area and entry and exit openings are surrounded by a sealing groove 1. The groove 1 can have a cross-sectional shape as illustrated in Fig. 2. A rectangular section seal 2, the side surfaces 3 and 4 (Fig. 3) of -which extend parallelly, is inserted into the groove 1. As is evident from Fig. 3, projecting, preferably wedge-shaped protrusions are situated at the lower half of the side surfaces 3 and 4. The protrusions can be provided with ramps at one side thereof or, as shown in Fig. 4, at both sides thereof. Fig. 5 shows a rectangular section groove 1 the width 8 of which is so selected relative to the minimum width 7 of the seal 2 that a problemfree insertion of the seal into the groove 1 is possible without force. The maximum width 6 of the seal across the protrusions 5 is greater than the width 8 of the groove 1. When the seal is inserted into the groove, the wedge-shaped protrusions lay themselves against the seal side surfaces during pressing-in. After the detenting in the groove, the protrusions 5 endeavour. to re-erect themselves and this produces a clamping effect, whereby a slipping out of the seal out of the groove is prevented. The side surfaces of the groove 1 can depart from parallelism by + 20. As shown in Fig. 6, use of the seal in a dovetail- shaped groove is also possible. Although higher production effort is required for the manufacture of the dovetail groove in this case, insertion of the seal is possible without great effort.

Fig. 7 shows a seal 2 which has wedge-shaped protrusions 5 in interrupted sequence only at discrete locations, so that a wedging effect is achieved only at those locations.

A heat exchanger embodying the invention may thus have the advantage that sealing of the heat exchanger plates one relative to the other is provided without gluing of the seals in the plates or requiring additional functional elements in the grooves. A simple insertion of the seal into the groove is possible without force and with simultaneous wedging of the seal in place, so as to exclude dropping- out during transport or during the manipulation of the plat es.

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Claims

CLAIMS 1. A heat exchanger comprising a plurality of heat exchanger plates

held tightly together in frame means and a plurality of sealing elements arranged in circumferential grooves in the plates and sealing the plates relative to each other, each sealing element being provided at two mutually opposite side surfaces thereof with deformable protrusions disposed in the respective groove and the width of the sealing element between the extremities of the protrusions in undeformed state being greater than the minimum width of the groove.
2. A heat exchanger as claimed in claim is rectangular in cross-section.

1 ' wherein each of the grooves
3. A heat exchanger as claimed in claim 1, wherein each of the grooves is trapezium-shaped in cross-section and widens in direction towards its open side.
4. A heat exchanger as claimed in claim 1, wherein each of the grooves is trap ezi um-s haped in cross-section and narrows in direction towards its open side.
5. A heat exchanger as claimed in any one of the preceding claims, wherein each of the grooves is substantially wedge-shaped.
6. A heat exchanger -as claimed in any one of the preceding claims, wherein the protrusions on each sealing element are interrupted in the longitudinal direction of the respective groove.
7. A heat exchanger as claimed in any one of the preceding claims, wherein said side surfaces of each sealing element are substantially parallel to each other.
8. A heat exchanger as claimed in any one of claims 1 to 6, wherein said side surfaces of each sealing element or mutually opposite side wal Is of each groove extend at an angle of substantially 2' relative to each other.
9. A heat exchanger substantially as hereinbefore described with reference to Figs. 1, 2, 4 and 6 of the accompanying drawings.
10. A heat exchanger substantially as hereinbefore described with reference to Figs. 3 and 5 of the accompanying drawings.
11. A heat exchanger substantially as hereinbefore described with reference to Fig. 7 of the accompanying drawings.

Published 1989 at The Patent Office, State House, 66/71 HighHolbornLondon WCIR4TP.Further copies maybe obtainedfromThe PatentOfnee. Was Brancii, St Mary Cray, Orpington, Kent BR5 3W. Printed by Multiplex tealmiques ltd, St Mary Cray Kent, Con. 1/87 p 1.

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