GB2070223A

GB2070223A - Heat exchanger

Info

Publication number: GB2070223A
Application number: GB8006062A
Authority: GB
Original assignee: Covrad Ltd
Current assignee: Covrad Ltd
Priority date: 1980-02-22
Filing date: 1980-02-22
Publication date: 1981-09-03

Abstract

A heat exchanger is of the kind having a tube plate 13 through which heat exchanger tubes are located. A cover 14 is located over the tube plate to define a header tank 15 into which the tubes open. To provide an easily assembled and detachable construction of header tank which is leakproof the peripheral edge of the cover 14 has a flange 21. The edge of the tube plate has a gutter 17/18 in which is received a seal 19 (e.g. of rubber or plastics). The cover flange 21 is located in the gutter against the seal 19 and the tube plate and cover are secured together by clips 22 engaging around the gutter and the flange. <IMAGE>

Description

SPECIFICATION Heat exchanger This invention relates to heat exchangers, and relates in particular to large heat exchangers of the kind having a plurality of tubes secured in at least one tube plate, the tube plate defining, with a cover, a header tank or manifold. The term "large heat exchanger" in this specification means one in which the major dimension of the tube plate is at least 600 mm; in practice it is often very much larger Conventional practice is to secure the cover to the tube plate by means of bolts passing through a peripheral flange on the cover and through the tube plate. Numerous attempts have been made to provide means to secure the cover to the tube plate which renders the cover more quickly detachable than when using bolts, leak-proof in normal service, and relatively cheap to manufacture.The present invention provides a construction which reconciles these three conflicting objectives.

According to the invention, a heat exchanger includes at least one tube plate, a plurality of tubes secured in said tube plate, and a cover which defines with the tube plate a header tank or manifold into which the tubes open, the cover being rigid, having side walls formed with a peripheral flange around the open end of the cover, the tube plate being formed around its periphery by a gutter defined by a first portion, which extends in a first direction at an angle of at least a right angle to the plane of the main portion of the tube plate, and a second portion which is joined to the first portion and extends in the opposite sense to make an acute angle with the plane of the main portion of the tube plate, a sealing ring or gasket lying in the angle between said first and second portions, the cover being in contact with the sealing ring or gasket and surrounding at least the main portion of the tube plate, and a plurality of clips which are either crimped or sprung over said peripheral flange and around the junction of said first and second portions of the tube plate, the clips securing the cover to the tube plate.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings, of which Figure 1 is a general view of a heat exchanger in accordance with the invention, and Figure 2 is a cross section showing a detail.

Referring to the drawings, the heat exchanger includes a number of parallel tubes 11, for example four rows each of 1 20 tubes.

In the example shown, a large number of parallel secondary-surface elements 1 2 are provided at right angles to the tubes, the latter passing through aligned holes in the elements 1 2 and being in contact with them so that heat may flow between the fluid passing through the tubes 11 and the fluid which passes over the elements 12 The invention may equally be applied to heat exchangers which have corrugated elements extending between adjacent tubes, the apices of the corrugations being maintained in contact with the tubes, for example, by means of brazing or soldering.

The tubes 11 are received in apertures in respective tube plates 13, one at each end, to which they are secured by brazing or soldering. The tube plates may be made of brass, for example 1 mm thick. The tube plates 13, together with adjacent covers 14, define header tanks or manifolds 1 5 to or from which fluid flows through the tubes, and the header tanks are provided respectively with an outlet or inlet for the fluid. To secure a cover 1 4 to the respective tube plate 1 3 in a manner which is leak-proof in normal service, but also readily detachable and capable of manufacture using a single press tool and die, the tube plate 1 3 is formed around its entire periphery with a part having the cross-section shown in Fig. 2.Surrounding the tube plate main portion 1 6 in which the tubes 11 are received, the tube plate is integrally formed with a first portion 1 7 extending substantially at right angles to the plane of the tube plate, the first portion being joined to a second portion 1 8 which extends outward and lies in a plane which makes an acute angle, for example an angle of 30 to the plane of the main portion 1 6 of the tube plate. It will be appreciated that the radius of curvature at the junction of the main portion 1 6 and the first portion 17, and that of the junction of the first portion 1 7 and the second portion 18, will be such that the periphery of the tube plate can be formed by a simple tool and die.

The inclination between the main portion 1 6 and the first portion 1 7 can be at an angle of between 90"-135". If nominally at a right angle, the angle can be rather greater (for example 2" or 3 greater) than a right angle to provide the necessary draw.

Conveniently the corner radii at the junction of portion 1 7 with portion 1 6 and of portion 1 8 with portion 1 7 are about 1 mm and the distance between the centre of the corner radii is 2-4 mm.

In the angle between the first portion 1 7 and the second portion 1 8 a gasket 1 9 of rubber, plastic or similar material is provided, the size and cross-section of which are such that it in operation does not extend up to the plane of the upper face of the main portion 1 6 of the tube plate. In its unstressed state the gasket 1 9 may be of circular cross-section and about 3.5 mm in diameter.

The cover 1 4 has side walls 20, the spacing of which is that they just surround the first portion 1 7 around the periphery of the tube plate, and at the base of the side walls 20 the cover is formed with an outward peripheral flange 21. The cover will thus be in contact with the gasket 1 9 around the whole periphery, and the parts are so dimensioned that the cover is not in contact with the second portion 1 8 of the tube plate. The cover is formed of steel sheet of, for example, 2mm (approx.

0.080 inch) thickness and is thus much more rigid than a cover made of plastics.

Moreover, the dimensions are such that in service the cover 1 4 cannot ride up over the upper surface of the tube plate, but is prevented from lateral movement by the first portion 1 7.

To secure the cover 1 4 to the tube plate 13, there are provided a number of mild steel clips 22. Preferably a number of clips 22 is provided on each of the four edges of the tube plate, but, if preferred, a single elongated clip may be provided on each edge.

With a long narrow tube plate, having say a single row of tubes an elongated clip on each of the long sides will be adequate in certain applications.

In cross-section, each clip 22 has three portions; two of the portions form a V, a portion 23 lying over the flange 21 and an intermediate portion 24 lying against the second portion 1 8 of the tube plate. At the end of portion 24 furthest from portion 23, a third portion 25 extends for a short distance at an angle to the intermediate portion 24, so as to engage within the first portion 1 7 of the tube plate.

Each clip 22 is engaged by positioning it with portions 24, 25 below portion 1 8 of the tube plate and with portion 23 over the flange 21, moving it inward, and crimping it with the portion 25 around the angle at the junction of portions 1 7 and 1 8 of the tube plate.

In a modification, the angle between the main portion 1 6 and the first portion 1 7 may be obtuse, for example 1 35', and in this case each clip 22 while it is of the form described, is made of spring steel and is sprung into position. In this case the parts are so dimensioned that the clip can be opened wide enough to pass over portion 18 and flange 21 before springing inward into the position which it occupies in service.

Claims

1. A heat exchanger including at least one tube plate, a plurality of tubes secured in said tube plate. a cover which defines with the tube plate a header tank or manifold into which the tubes open and around the free edge of which manifold is formed a peripheral flange, the tube plate having a gutter formed around its periphery. the gutter comprising a first portion extending at an angle of at least a right angle to the main plane of the tube plate and a second portion extending from and in the opposite direction to the first portion at an acute angle to the main plane of the tube plate, a sealing element lying between the first and second portions of the gutter, the peripheral flange of the cover contacting the sealing element and surrounding the tube plate, and a plurality of clips engaged over the peripheral flange of the cover and over the first and second portions of the gutter to secure the cover to the tube plate.

2. A heat exchanger according to claim 1 wherein the clips are each in three portions one of which locates over the peripheral flange of the cover, another of which locates against the first portion of said gutter, and a further portion of the clip, intermediate the other two portions, locates against said second portion of the gutter.

3. A heat exchanger according to claim 1 or 2 wherein the clips are crimped or sprung into position to secure the cover to the tube plate.

4. A heat exchanger according to any one of the preceding claims wherein the first portion of the gutter lies at 90-135" to the main plane of the tube plate.

5. A heat exchanger according to any one of the preceding claims wherein the second portion of the gutter lies at substantially 30G to the main plane of the tube plate.

6. A heat exchanger according to any one of the preceding claims wherein the junctions between the tube plate and the gutter and between the first and second portions of the gutter are radiused to have radii of the order of 1 mm.

7. A heat exchanger substantially as described with reference to the drawings.