EP0186592A1 - Plate heat exchanger - Google Patents

Abstract

Plate exchanger comprising a multiplicity of metal plates (10-15) juxtaposed and separated by intervals (A, B), one interval out of two (A) being intended for the circulation of a first fluid and the other intervals (B) being intended for the circulation of a second fluid substantially parallel to the first, each plate being connected at its periphery to the two adjacent plates in a sealed manner, so as to close, at least partially said intervals (A, B) while providing inlet and outlet ports for said fluids, said plates being assembled in pairs (10-11, 12-13, 14-15) by linear welding (16, 17) in two opposite end zones of the plates of each pair, characterized in that at least one plate (14) per pair comprises a wing (20), at least in one of said end zones and in the vicinity of said weld (16), folded substantially at right angles and connected in its zone marginal free to a facing plate (13) is from a neighboring pair, by linear welding.

Description

The invention relates to a plate heat exchanger.

In conventional solutions, plate exchangers are produced by stacking a multiplicity of plates with interposition of seals between successive plates, these seals being open at intervals so as to put intermediate intervals between two plates into communication with intake and intake manifolds. fluid return. As known, the successive intervals are connected in this way alternately to intake and return manifolds conveying a first fluid and intake and return manifolds conveying a second fluid, the term fluid here encompassing all types of liquids and gas, the two fluids exchanging heat energy through the plates during their journey in the intervals between plates.

The presence of such seals limits the field of use of these exchangers, in particular with regard to temperature, pressure and certain fluids, such as corrosive fluids (acids) or solvents.

Finally, maintaining the plates in a stacked condition necessarily requires providing support plates at the ends of the stack, which are connected to one another by tie rods distributed around the periphery of the exchanger plates. The resistance of the support plates and tie rods is conditioned by the higher of the pressures of the two fluids circulating in the exchanger.

To avoid the presence of seals, solutions are known in which the plates are assembled together by welding at their periphery.

In a first solution, each plate is assembled to an adjacent plate by welding along two opposite edges, and to the other adjacent plate along two other opposite edges, so that the circulation of the fluids in the intervals between successive plates must be performed at cross currents.

In a second solution, allowing the circulation of fluids with parallel currents, the plates are first welded in pairs along at least two opposite edges, then the pairs thus formed are grouped inside a calender , which is sometimes simply made up of sealing strips welded on one side to another pair of plates, along the same edges and on the other side to another pair of plates, close to the first or not.

It is noted, however, that in the latter type of solution, there are many weld beads, some of which are sometimes superimposed, which, in addition to the manufacturing cost, introduces metallurgical distortions in the metal surrounding the plates. Finally, in the event of a weld rupture, it is particularly awkward to carry out repairs without first removing certain sealing strips. In certain places, there is sometimes a stack such of metal of the exchanger plates and of weld filler metal that these exchangers do not support differential expansions well.

In order to overcome these drawbacks, the present invention provides a plate exchanger comprising a multiplicity of metal plates juxtaposed and defining intervals between them, one interval out of two being intended for the circulation of a first fluid and the other intervals being intended to the circulation of a second fluid substantially parallel to the first, each plate being connected at its periphery to the two adjacent plates in a leaktight manner while providing inlet and outlet orifices for said fluids, characterized in that said plates are assembled in pairs by linear welding in two opposite end zones of the plates of each pair, at least one plate in pairs comprising a wing, at least in one of said end zones and in the vicinity of said weld, folded substantially at right angles and connected in its free marginal zone to a plate opposite a neighboring pair, by linear welding.

• la figure 1 est une vue en perspective avec arrachements partiels d'un échangeur selon l'invention,
• les figures 2, 3, 4, 5 et 6 sont des vues illustrant le conformage et l'assemblage des plaques de l'échangeur de la figure 1, prises en coupe transversale;
• la figure 7 est une vue en perspective illustrant un détail d'assemblage de deux plaques de l'échangeur,
• la figure 8 est une vue d'ensemble en perspective avec arrachements, d'une extrémité d'échangeur totalement assemblé, et;
• les figures 9 à 13 sont des vues semblables à celle de la figure 6, illustrant diverses variantes de l'invention.

The details and advantages of the invention will appear more clearly on reading the description which follows, with reference to the accompanying drawings, in which:

• FIG. 1 is a perspective view with partial cutaway of an exchanger according to the invention,
• Figures 2, 3, 4, 5 and 6 are views illustrating the shaping and assembly of the plates of the exchanger of Figure 1, taken in cross section;
• FIG. 7 is a perspective view illustrating a detail of assembly of two plates of the exchanger,
• Figure 8 is an overall perspective view with cutaway, of a completely assembled exchanger end, and;
• Figures 9 to 13 are views similar to that of Figure 6, illustrating various variants of the invention.

The exchanger according to the invention consists of a stack of juxtaposed metal plates in the form of! 1> - - so rectangular and six of these plates 10, 11, 12, 13 are shown in FIG. 1, 14 and 15, some of which have been cut transversely so as to highlight the particularities of assembly.

First, we notice that the plates are assembled in pairs, 10-11, 12-13 and 14 = 15.

The first pair, 10-11, is shown to its anterior edge while the other two pairs have been sectioned along different transverse vertical planes.

The plates of the same pair define between them an interval designated by the reference A, and the pairs define between them intervals designated by the reference B. As is well known, the intervals A are intended for the circulation of a first fluid and the intervals B are intended for the circulation of a second fluid, with the aim of ensuring a heat exchange between them through the plates.

The intervals A and B are closed, at least at the top and bottom by the fact that each plate is connected at its periphery to the two adjacent plates, in a sealed manner. The plates of the same pair, for example 14-15, are welded together by linear welds 16 and 17 in their upper and lower end zones. In accordance with the invention, these welds can be produced, for example, by electrical welding with a thumbwheel, as will be explained below.

The plates have wings 18, 19, 20, 21 connected to their upper and lower end zones, and folded substantially at right angles, which makes it possible to assemble the pairs of plates together.

In the embodiment shown, the pairs are assembled side by side, so that the wings 20, 21 of a plate (14) of a first pair (14-15) are arranged edge to edge relative to the wings ( 22, 23) of the plate 13 opposite the neighboring pair (12-13) and the wings are welded to each other (20 and 22, 21 and 23) by a linear weld bead, for example by welding bow.

As illustrated in FIG. 1, the plates of the same pair (10-11) are also welded to each other along their anterior extreme zone 24, either by electrical welding with a thumbwheel, or by cord arc welding.

It will be understood that the same is true in the posterior end zones of the plates, which have not been shown for convenience.

Fluid inlet and outlet openings to the intervals A are provided in the form of interruptions in the upper linear welds 16 and lower 17. A single orifice 25 has been illustrated in FIG. 1, at the level of the upper weld 16, and in the vicinity of the anterior end zone 24. The other orifice, not shown, is arranged in the vicinity of the posterior end zone, optionally at the level of the upper weld 16 or the lower weld 17.

The pairs of plates are devoid of wings at their anterior and posterior end zones, so that there remain free openings between the pairs of plates, which thus constitute the inlet and outlet orifices for the fluid circulating in intervals B.

Finally, it can be seen in FIG. 1, that the plates have depressions 26 distributed substantially regularly over the surface of the plates and whose role is multiple.

First, when two plates of a pair are joined (12- ₁ 3), their depressions 26 come into mutual contact, which ensures a constant width to the gaps A, even when the fluid pressure in the intervals B exceeds that which prevails in the intervals A.

Secondly, the plates are welded to each other by points at the bottom of the depressions, which prevents - the spacing of the plates when, on the contrary, the fluid pressure prevailing in the intervals A exceeds that which prevails in intervals B.

Thirdly, these depressions create obstacles to the flow of the fluid in the intervals A and the turbulences which result from it improve the heat exchanges between this fluid and the plates.

These depressions can be arranged in regular rows as illustrated, or in staggered rows or according to any predetermined arrangement.

The sequence of formation and assembly of the plates is illustrated in Figures 2 to 7 in which the plates are shown in schematic cross-section.

The insulated plate 10 illustrated in Figure 2 was obtained in a conventional manner by stamping the depressions 26 and folding the wings square.

This plate is then assembled to a second plate 11 by spot welding at the bottom of the depressions 26 (Figure 3).

Weld beads 16, 17 are then produced in the vicinity of the feet of the wings, by electrical welding using knobs 28, 29 (FIG. 4), it being noted that the plates initially spaced from one another ( Figure 3) are forced to move together under the pressure of the knobs. This is made possible by the small thickness of the plates and their small spacing and avoids a prior drilling operation.

A first pair of plates (10-11) is then assembled to a second pair of plates (12-13) constituted in the above manner, by presenting the wings of both in edge-to-edge relationship and then by producing a linear weld bead, for example by arc welding.

This assembles the number of pairs of plates required to obtain the desired exchange surface.

The plates thus assembled form a one-piece assembly with which inlet and outlet manifolds are associated for the fluids circulating in the intervals A and B.

As illustrated in FIG. 8, a manifold 30 in the form of a rectangular pipe is welded to the perimeter of the front end of the exchanger plates. A similar manifold, not shown, is welded to the perimeter of the rear end of the exchanger plates. These two collectors used to convey the fluid circulating in the intervals B.

A semi-cylindrical manifold 32 is welded transversely to all of the plates, so as to cover all of the orifices 25 for the fluid flowing in the intervals A.

The front edge (according to the arrangement of FIG. 8) of the collector 32 is welded to the upper face of the collector 30, and its rear edge is welded to a pseudo-planar and almost continuous surface, formed by the succession of the wings of the plates exchanger. These welds are preferably carried out with the addition of metal so as to provide the required seal.

As a variant, the front edge of the manifold 32 can also be welded to the wings of the exchanger plates, provided that the orifices 25 are formed somewhat behind the front edges 24 of the plates.

The detail illustrated in FIG. 7 makes it possible to understand the manner in which the orifices 25 are produced. A wedge 34 in the form of a wedge is introduced between two plates of a pair ₁ 0-11 so as to prevent the advance of the welding knobs - 28, 29 in the area of the orifice. We can also do without wedge 34 and simply stop the advance of the welding wheels to a predetermined location, insofar as the plates are kept apart by the presence of depressions 26 forming spacers. Strictly speaking, account should be taken of the fact that the plate wings protrude a greater distance at the level of the orifices and provide for a cutting operation so that the wings have a straight edge, but this does not will in practice by always be necessary insofar as the intervals are thin (a few millimeters).

Because the pairs of plates are welded to each other by points at the bottom of the depressions 26, the pressure of the fluid flowing in the intervals A has no effect on the exchanger.

On the other hand, when the fluid circulating in the intervals B presents a certain pressure, support plates 36, 38 must be provided in the vicinity of the exchanger plates situated at the ends (FIG. 6). These support plates are juxtaposed, without fastening, the heat exchanger plates so as to allow differential expansion, and are joined to each other by tie rods ₄ 0, sized and distributed to absorb the forces due to the Pession of the fluid circulating in the intervals B.

From the basic embodiment which has just been described, various variants have been designed, without claiming to have made an exhaustive exploration of them, as illustrated in FIGS. 9 to 13.

In FIG. 9, only one plate out of two comprises wings 18, 19, the other plates being devoid of wings.

. For this embodiment, after having assembled the plates in pairs, the pairs are assembled by welding the wings of a plate directly to the edges of a plate devoid of wings of the neighboring pair.

As illustrated, the plates carrying the wings are entirely flat and the plates devoid of wings carry the depressions 26. There are thus two plates of different type, but on which conforming operations of a different nature are carried out; folding in one case, stamping in the other.

In FIG. 10, all the exchanger plates are identical and have a wing 18 on a single edge and depressions on part of their surface.

When assembling in pairs, the plates are placed head to tail, then the pairs are assembled, as before, by welding the edge of the wings to the edge of the facing plates.

In FIG. 11, the wings are extended by a flap 42, and the ends of plates devoid of wings have an extension 44. The flaps and the extensions are welded flat by electric welding with a seam.

In this case, however, account should be taken of the projections represented by the flaps and the extensions for assembling the semi-cylindrical manifolds for the fluid flowing in the intervals A. By way of example, regularly distributed notches can be provided along the rear edge of the manifold, to receive these projections.

According to the variant of Figure 12, the exchanger plates are completely flat and during assembly in pairs, is interposed therebetween metallic spacers ₄ 6 which are spot welded to both plates.

According to the variant of FIG. 13, the plates are of the corrugation type, the corrugations of one (48) having a different orientation from the corrugations (50) of the adjacent plate.

The plates are joined in pairs by seam welding along their edge, as seen above. It is also possible to provide or not to join the two plates by spot welds in the zones where the top of the undulations of one is in contact with the bottom of the undulations of the other, as illustrated by the points P in the figure.

The structural community of these various variants is therefore that the plates are assembled in pairs by linear welding without the addition of metal in two opposite end zones, and that at least one plate in each pair has a wing located in at least one of these extreme zones and in the vicinity of the linear weld, folded back to the square and connected in its free marginal zone to a plate opposite a neighboring pair, by linear weld.

• - L'ensemble des plaques d'échangeur forme un tout monobloc qui peut être traité et manipulé comme tel.
• - Il n'est plus besoin d'enfermer l'ensembles des plaques dans une calandre puisque cet ensemble comporte par lui-même sa propre calandre. L'échangeur est par conséquent particulièrement léger.
• - Toutes les soudures linéaires entre plaques sont directement accessibles depuis l'extérieur, aussi bien pour des besoins d'inspection que pour des réparations.
• - Lorsque seul le fluide circulant dans les intervalles A est sous pression, il n'est pas besoin de prévoir de plaques de renfort assemblées par tirants.
• - Les intervalles B sont dépourvus d'obstacles et accessibles via des orifices situés en alignement, de sorte que l'on peut y faire circuler des fluides chargés d'impuretés avec un faible risque de colmatage et, si de tels colmatages se produisent, leur nettoyage sera particulièrement aisé.
• - La construction d'échangeurs se prête particulièrement bien à la préfabrication, à plusieurs niveaux;
  • a) formage des plaques d'échangeur,
  • b) assemblage des plaques par paires,
  • c) assemblage d'un nombre prédéterminé de plaques,
  • d) assemblage des collecteurs d'entrée/sortie pour le fluide "B".

In all of the foregoing, the essential advantages of the invention, mentioned below, will be noted, without giving them an order of particular importance.

• - The set of exchanger plates forms a single unit which can be treated and handled as such.
• - There is no longer any need to enclose all of the plates in a grille since this assembly has its own grille by itself. The exchanger is therefore particularly light.
• - All linear welds between plates are directly accessible from the outside, both for inspection purposes and for repairs.
• - When only the fluid circulating in the intervals A is under pressure, there is no need to provide reinforcement plates assembled by tie rods.
• - The intervals B are free of obstacles and accessible via orifices located in alignment, so that it is possible to circulate therein fluids laden with impurities with a low risk of clogging and, if such clogging occurs, their cleaning will be particularly easy.
• - The construction of exchangers is particularly suitable for prefabrication, on several levels;
  • a) forming the exchanger plates,
  • b) assembly of the plates in pairs,
  • c) assembly of a predetermined number of plates,
  • d) assembly of the inlet / outlet manifolds for the fluid "B".

• - Lorsque la pression du fluide circulant dans les intervalles B est relativement faible, les plaques de renfort aux extrémités pourront être accrochées directement aux dernières plaques sans qu'il soit besoin de prévoir de tirants, les efforts de traction étant encaissés par la succession des ailes des plaques soudées les unes aux autres.
• - Toutes les plaques étant en excellent contact thermique les unes avec les autres, leur température sera donc très uniforme et les phénomènes de dilatation différentielle sont négligeables.
• - Toutes les soudures linéaires entre plaques peuvent être réalisées sur des machines automatiques, ce qui accroît la fiabilité pour un coût réduit.

Other possibilities will be obvious to those skilled in the art.

• - When the pressure of the fluid flowing in the intervals B is relatively low, the reinforcement plates at the ends can be hung directly on the last plates without the need to provide tie rods, the traction forces being collected by the succession of the wings plates welded to each other.
• - All the plates being in excellent thermal contact with each other, their temperature will therefore be very uniform and the phenomena of differential expansion are negligible.
• - All linear welds between plates can be carried out on automatic machines, which increases reliability at a reduced cost.

Claims (12)

1. Plate exchanger comprising a multiplicity of metal plates (10-15) juxtaposed and separated by intervals (A, B), one interval out of two (A) being intended for the circulation of a first fluid and the other intervals ( B) being intended for the circulation of a second fluid substantially parallel to the first, each plate being connected at its periphery to the two adjacent plates in a leaktight manner, so as to close, at least partially, said intervals (A, B) while providing inlet and outlet openings for said fluids, said plates being assembled in pairs (10-11, 12-13, 14-15) by linear welding (16, 17) in two opposite extreme zones of the plates of each pair ,
characterized in that a plate (14) at least in pairs comprises a wing (20), at least in one of said end zones and in the vicinity of said weld (16), folded back substantially square and connected in its free marginal zone to a plate (13) opposite a neighboring pair, by linear welding. 2. Exchanger according to claim 1, characterized in that the plates of the same pair (14-15) are fixed to each other by welding points distributed over their surface. 3. Exchanger according to claim 2, characterized in that said plates have depressions (26) and that said weld points are formed at the bottom of said depressions. 4. Exchanger according to claim 2, characterized in that said plates are planar and that said welding points are made via spacers (46) interposed between said plates. 5. Exchanger according to claim 2, characterized in that said plates have corrugations (48, 50) of different orientations. 6. Exchanger according to any one of the preceding claims, characterized in that the linear welding between plates of the same pair is carried out by electric welding with a thumbwheel (28, 29). 7. Exchanger according to claim 6, characterized in that said linear weld between plates of the same pair is locally interrupted so as to provide orifices (25) for a fluid flowing in the gap (A) between said plates. 8. Exchanger according to any one of the preceding claims, characterized in that the linear welding between the wing of a plate and the facing plate is carried out with an arc. 9. Exchanger according to any one of claims 1 to 8, characterized in that each plate has a wing in its two opposite end zones. 10. Exchanger according to any one of claims 1 to 8, characterized in that each plate has a wing in only one of its two opposite end zones. 11. Exchanger according to any one of claims ₁ to 8, characterized in that each pair is composed of a plate devoid of wings and a plate comprising wings in its two opposite end zones. 12. Exchanger according to any one of claims 1 to 11, characterized in that each pair is composed of a plate provided with depressions.

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