EP0571263B1 - Stack of plates for a heat-exchanger and method of assembling same - Google Patents

Abstract

The subject of the invention is a group of plates (1) for a heat-exchanger, of the type comprising a stack of plates (20 - 30) which are parallel to each other, each plate (20 - 30) including edges (21 - 31; 22 - 32) with a smooth surface, and a central part (23 - 33) which is corrugated to form with the associated plates a double circuit for circulating two independent fluids in counterflow, the said group being composed of a multitude of elements which are superposed and are each formed by a pair (A) of plates (20 - 30) assembled together. The plates (20 - 30) of each pair (A) are assembled together by means (10) for linking the superposed elements which are connected together by a continuous or discontinuous longitudinal weld bead (14). A further subject of the invention is a method of assembly and a heat-exchanger provided with such a group of plates. <IMAGE>

Description

The subject of the present invention is a bundle of plates for a heat exchanger and a method of assembling such a bundle of plates.

The present invention also relates to a heat exchanger provided with such a bundle of plates.

There are generally two types of heat exchangers.

The first type of heat exchanger comprises a bundle of tubes in the shape of a "U" or a bundle of straight tubes, in which a fluid circulates.

However, this type of exchanger is of an expensive design and the thermal efficiency is limited, given that the number of tubes depends on the space available which is in most cases limited.

The second type of heat exchanger comprises a bundle of plates arranged contiguously and parallel to each other.

The plates made of thin sheets, most often made of stainless steel, have edges with a smooth surface and a central part provided with corrugations by which they are in contact with one another and by which they delimit a double circulation circuit of two independent fluids and against the current from one end to the other of the exchanger.

The assembly of the plates to form the bundle is carried out as follows.

First of all, the plates are stacked by inserting, between the longitudinal edges of each plate, a tab forming a spacer.

The longitudinal edges of the plates being of sufficient width to allow the search for the ideal position of the associated tongue, are leveled so as to produce on each side of the beam a flat and uniform vertical surface in accordance with the requirements of the subsequent welding operation.

Then, a layer of solder is deposited over the entire height of each lateral surface of the bundle to form a sealed solder wall.

It can therefore be seen that such an embodiment of the bundle requires considerable time for the execution of the welding operation and includes an operation intended to level the longitudinal edges of the plates, which results in a loss of material.

In addition, this technique has another drawback.

Indeed, the tightness test, before the use of the beam, is only possible after the assembly of all the plates.

Consequently, in the event of a leak, the search for the origin of the leak is delicate and tedious, given that this search is only possible by eliminating zones.

One can easily imagine the difficulties that arise from this.

Also known in FR-A-1 224 753 is a bundle of plates for a heat exchanger, of the type comprising a stack of plates parallel to each other, each plate having edges with a smooth surface and a central part provided with corrugations. to form with the associated plates a double circulation circuit of two independent and counter-current fluids. The bundle is made up of a multitude of superimposed elements each formed by a pair of plates assembled together, the plates of each pair being assembled together by connecting means.

The object of the present invention is to avoid disadvantages mentioned above by proposing a simpler and less expensive plate bundle to produce and whose leakage test is facilitated.

The present invention therefore relates to a bundle of plates for a heat exchanger, of the type comprising a stack of plates parallel to each other, each plate having edges with a smooth surface and a central part provided with corrugations to form with the plates. associated with a double circulation circuit of two independent and counter-current fluids, said beam being composed of a multitude of superimposed elements and each formed by a pair of plates assembled together, characterized in that the plates of each pair are assembled together by connecting means, superimposed elements connected to each other by a longitudinal weld bead, continuous or discontinuous, formed by at least one longitudinal spacer disposed below each of the longitudinal edges of the corresponding pair of plates and by a corner cleat disposed at the angles of said pair of plates, the longitudinal edges and the angles being fixed to said spacers and said corner cleats by a continuous weld bead extending parallel to the direction of circulation of the fluids.

• chaque couple de plaques est formé par une plaque supérieure et une plaque inférieure dont les bords longitudinaux sont jointifs et dont les bords transversaux comportent au moins une partie jointive, au moins une partie non jointive desdits bords transversaux ménageant au moins une entrée et au moins une sortie pour l'un des deux fluides et ladite partie jointive desdits bords transversaux de chaque couple de plaques ménageant avec ladite partie jointive des couples de plaques adjacents au moins une entrée et au moins une sortie pour l'autre des deux fluides,
• ladite partie non jointive de chaque couple de plaques est formée, d'une part, par au moins un décrochement prévu sur les bords transversaux de la plaque supérieure et, d'autre part, par au moins un décrochement prévu sur les bords transversaux de la plaque inférieure,

According to other preferred characteristics of the invention:

• each pair of plates is formed by an upper plate and a lower plate whose longitudinal edges are contiguous and whose transverse edges comprise at least one contiguous part, at least one non-contiguous part of said transverse edges providing at least one entry and at least one outlet for one of the two fluids and said contiguous portion of said transverse edges of each pair of plates providing with said contiguous portion pairs of adjacent plates at least one inlet and at least one outlet for the other of the two fluids,
• said non-contiguous part of each pair of plates is formed, on the one hand, by at least one recess provided on the transverse edges of the upper plate and, on the other hand, by at least one recess provided on the transverse edges of the bottom plate,

• on superpose deux plaques pour former des couples de plaques dont les bords longitudinaux et au moins une partie des bords transversaux sont jointifs, au moins une partie non jointive desdits bords transversaux ménageant au moins une entrée et au moins une sortie pour l'un des deux fluides,
• on dispose au moins une entretoise longitudinale sur la face inférieure des bords longitudinaux et un taquet de coin sur la face inférieure des angles de chaque couple de plaques,
• on soude par un cordon de soudure continu chaque couple de plaques sur les entretoises longitudinales et sur les taquets de coin pour maintenir les plaques,
• on met en place des taquets de bout au niveau des extrémités des parties non jointives des bords transversaux de chaque couple de plaques,
• on soude les parties jointives des bords transversaux et les taquets de bout sur lesdits bords transversaux des plaques de chaque couple de plaques,
• on réalise une épreuve d'étanchéité pour chaque couple de plaques ainsi formé,
• on superpose les couples de plaques,
• et on soude les entretoises longitudinales et les taquets de coin superposés par un cordon de soudure continu ou discontinu.

The present invention also relates to a method of assembling such a bundle of plates, characterized in that:

• two plates are superimposed to form pairs of plates whose longitudinal edges and at least part of the transverse edges are contiguous, at least one non-contiguous part of said transverse edges providing at least one inlet and at least one outlet for one of the two fluids,
• there is at least one longitudinal spacer on the underside of the longitudinal edges and a corner cleat on the underside of the angles of each pair of plates,
• each pair of plates is welded by a continuous weld bead on the longitudinal spacers and on the corner cleats to hold the plates,
• end caps are put in place at the ends of the non-contiguous parts of the transverse edges of each pair of plates,
• the contiguous parts of the transverse edges are welded and the end tabs on said transverse edges of the plates of each pair of plates,
• a leakproofness test is carried out for each pair of plates thus formed,
• we overlap the pairs of plates,
• and the longitudinal struts and the superimposed corner tabs are welded by a continuous or discontinuous weld bead.

The present invention also relates to a plate heat exchanger comprising an enclosure resistant to internal pressure in which is placed a bundle of plates as defined above.

• la Fig. 1 est une vue schématique en perspective d'une partie d'un faisceau de plaques selon l'invention,
• la Fig. 2 est une vue partielle en coupe transversale du faisceau de plaques selon l'invention,
• la Fig. 3 est une vue schématique en perspective d'une plaque supérieure d'un couple de plaques,
• la Fig. 4 est une vue schématique en perspective d'une plaque inférieure d'un couple de plaques,
• la Fig. 5 est une vue schématique en perspective des moyens de liaison et des taquets de bout d'un couple de plaques du faisceau,
• la Fig. 6 est une vue partielle en coupe d'un couple de plaques du faisceau,
• la Fig. 7 est une vue de côté d'un taquet de coin des moyens de liaison d'un couple de plaques,
• la Fig. 8 est une vue de dessus d'un taquet de coin.

The invention will be better understood with the aid of the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

• Fig. 1 is a schematic view in perspective of part of a bundle of plates according to the invention,
• Fig. 2 is a partial view in cross section of the bundle of plates according to the invention,
• Fig. 3 is a schematic perspective view of an upper plate of a pair of plates,
• Fig. 4 is a schematic perspective view of a bottom plate of a pair of plates,
• Fig. 5 is a schematic perspective view of the connection means and the end stops of a pair of plates of the bundle,
• Fig. 6 is a partial sectional view of a pair of beam plates,
• Fig. 7 is a side view of a corner stopper of the means for connecting a pair of plates,
• Fig. 8 is a top view of a corner cleat.

As shown in Figs. 1 and 2, the bundle of plates designated as a whole by the reference 1 consists of a stack of superimposed elements each formed by a pair A of plates 20-30 parallel to each other.

Each plate 20 or 30 consists of a thin sheet, most often made of stainless steel or any other sufficiently ductile material.

Each pair A of plates consists of an upper plate 20 and a lower plate 30 superimposed.

The upper plate 20 shown in FIG. 3 has longitudinal edges 21 and transverse edges 22 with a smooth surface and a central part 23 provided with corrugations. The transverse edges 22 include at least one step 24.

The longitudinal edges 21 and the parts of the transverse edges 22 not having recesses 24 define a first plane, while the central part 23 and the upper face 24a of the recess (s) 24 define a second plane parallel to said foreground and in relief by compared to this one.

The bottom plate 30 shown in FIG. 4 has longitudinal edges 31 and transverse edges 32 with a smooth surface and a central portion 33 provided with corrugations. The transverse edges 32 have at least one recess 34.

The longitudinal edges 31 and the parts of the transverse edges 32 not having recesses 34 as well as the central part 33 define a first plane, while the lower face 34a of the recess (s) 34 defines a second plane, parallel to said foreground and in withdrawal from it.

To form each pair A of plates, the plates 20 - 30 are superimposed and bear one on the other, on the one hand, by their longitudinal edges 21 - 31 and by at least part of the transverse edges 22 - 32 which are therefore contiguous and, on the other hand, by the crests of the corrugations which form a first circuit for a heat exchange fluid.

According to an embodiment shown in Figs. 1, 3 and 4, each transverse edge 22 - 32 respectively of the upper plate 20 and the lower plate 30 has a recess 24 - 34.

The recesses 24 - 34 are located opposite each other and oriented in an opposite direction relative to the plane of joint of the plates 20 - 30 of the pair A of plates.

According to a preferred embodiment, the recesses 24 - 34 are located substantially in the middle of the transverse edges 22 - 32 of the plates 20 - 30.

As shown in Fig. 1, the recesses 24 - 34 define at one end of the bundle 1, an inlet 2, and at the opposite end an outlet for the first heat exchange fluid.

The pairs A of plates are superimposed and bear on each other in particular by the crests of the corrugations of the adjacent plates 20 - 30 thus forming a second circuit for another heat exchange fluid.

As shown in Fig. 1, the contiguous portions of the transverse edges 22 - 32 of each pair A of plates provide with the contiguous portions of the pairs A of adjacent plates, at one end of the bundle 1, at least one inlet and, at the opposite end of said bundle 1 , at least one outlet 3 for the second heat exchange fluid.

The heat exchange fluids circulate longitudinally from one end to the other of the bundle 1 and against the current.

The plates 20 - 30 of each pair A and the pairs A of plates are assembled to each other by connecting means 10.

These connecting means 10, shown in more detail in Figs. 2 and 5 to 8, are formed, on the one hand, by at least two longitudinal spacers 11 each arranged below the longitudinal edges 21 - 31 of the pair A of plates and, on the other hand, by four corner tabs 12 each arranged at an angle to said pair of plates.

The longitudinal spacers 11 and the corner tabs 12 have a thickness corresponding to the interval between the pairs A of adjacent plates.

The upper side of each spacer 11 has a longitudinal edge 11a delimiting a housing 11b intended to receive the longitudinal edges 21 - 31 of the pair A of associated plates and of depth substantially equal to the thickness of the plates 20 - 30 of said pair of plates.

The flange 11a and the housing 11b of each longitudinal spacer 11 extend over the entire length of said spacer.

The outer rim 11a has a height substantially equal to the thickness of the plates 20-30 of the pair A of associated plates to form, with the upper face of the longitudinal edge 21 of the upper plate 20 of said pair A of plates, a continuous flat surface and of support of the lower face of the spacer 11 of the pair of plates located above, as shown in FIG. 2.

The width of the housing 11b of each spacer 11 is substantially greater than the width of the longitudinal edges 21 - 31 of the plates 20 - 30 to allow the search for the ideal position of each spacer 11 relative to the plates 20 - 30.

The housing 11b of each spacer 11 comprises, near the rim 11a, a groove 11c intended to receive any burrs from the plates 20-30.

The plates 20 - 30 of each pair A of plates are fixed to the longitudinal spacers 11 by their longitudinal edges 21 - 31, by means of a weld bead 13 continuous and parallel to the direction of circulation of the heat exchange fluids.

The underside of each longitudinal spacer 11 has a groove 11d extending over the entire length of said spacer for positioning the raised portion of the weld bead 13 of the pair A of plates located below (Figs. 2 and 6 ).

As shown in Figs. 5, 7 and 8, each corner cleat 12 is formed by two perpendicular branches and has on its underside an outer rim 12a delimiting a housing 12b intended to receive the angle of the pair A of associated plates and of depth substantially equal to l thickness of the plates 20 - 30 of said pair of plates.

The width of the housing 12b of each corner cleat 12 is substantially greater than the width of the edges of the plates 20 - 30 to allow the search for the ideal position of each corner cleat 12 relative to the longitudinal spacers 11 and to the plates 20 - 30 .

The outer rim 12a of each corner cleat 12 has a height substantially equal to the thickness of the plates 20-30 of the pair A of plates associated to form with the upper face of the upper plate 20, a flat surface.

The housing 12b of each corner cleat 12 comprises, near the rim 12a, a groove 12c intended to receive any burrs from the plates 20-30.

The plates 20 - 30 of each pair A of plates are fixed to the corner cleats 12 by their angles also by means of the continuous weld bead 13.

The underside of each corner cleat 12 has a groove 12d (Figs. 7 and 8) for positioning the raised portion of the weld bead 13 of the pair A of plates located below.

Furthermore, the contiguous parts of the transverse edges 22 - 32 of the plates 20 - 30 of each pair A of plates are interconnected by a weld bead, not shown, to make a seal between the plates with the weld bead 13 20 - 30 of each pair A of plates.

The pairs A of plates each provided with the longitudinal spacers 11 and the corner cleats 12 are superimposed and fixed to each other by a continuous or discontinuous weld bead 14 deposited externally and at the joint plane of said spacers and said corner cleats .

Each end of the non-contiguous parts formed by the recesses 24 - 34 of the transverse edges 22 - 32 of each pair A of plates is provided with an end stop 15 (Fig. 5) connected to the plates 20 - 30 by a weld bead not shown.

The height of each end stop 15 is substantially equal to the height of the gap between the upper face 24a of the recess 24 and the lower face 34a of the recess 34.

The longitudinal spacers 11, the corner stops 12 and the end stops 15 are made of material compatible with the material constituting the plates 20 - 30, such as, for example, stainless steel.

The assembly of the plate bundle 1 according to the present invention is carried out as follows.

First of all, two plates 20 - 30 are superimposed so that the longitudinal edges 21 - 31 and the parts of the transverse edges not having recesses 24 - 34 are contiguous.

The pair A of plates thus produced is placed on two longitudinal spacers 11 and on four corner cleats 12 so that the longitudinal edges 21 - 31 and the angles of this pair A of plates are positioned respectively in the housings 11b and 12b.

The pair A of plates is fixed on the longitudinal spacers 11 and the corner cleats 12 by the continuous weld bead 13 to produce a mechanical connection at the interface of the plates 20 - 30, the spacers 11 and the corner cleats 12.

Next, the end tabs 15 are arranged at the ends of the non-contiguous parts of the transverse edges 22 - 32.

The contiguous parts of the transverse edges 22 - 32 are welded together and the end tabs 15 are welded to the transverse edges 22 - 32 of the plates 20 - 30.

Each pair A of plates is produced in an identical manner.

Following these various operations, each pair A of plates is subjected to a leakproofness test which facilitates possible interventions in the event of the detection of a leak.

The pairs A of plates are superposed and the longitudinal spacers 11 and the corner cleats 12 located one above the other are welded to each other by a weld bead 14 continuous or discontinuous in order to secure the assembly.

The bundle of plates thus formed is placed in an enclosure, not shown, resistant to internal pressure to constitute a heat exchanger.

This type of heat exchanger can operate for example up to temperatures of 600 ° C and above and for example up to pressures of 200 bar and above.

Such a bundle which does not require an operation intended to level the edges of the plates, nor a welding operation of the entire bundle on its lateral edges, therefore has the advantage of being easier to assemble and therefore less expensive, while having a level of quality that meets the highest standards.

Claims (19)

1. Bank (1) of plates for a heat exchanger, of the type comprising a stack of plates (20-30) parallel to each other, each plate (20-30) including smooth-surface edges (21-31; 22-32) and a central portion (23-33) equipped with undulations in order to form, with the associated plates, a dual circuit for countercurrent flow of two independent fluids, said bank being composed of a multitude of superposed elements each formed by a pair (A) of plates (20-30) which are joined together; characterized in that the plates (20-30) of each pair (A) are joined together by means (10) for linking the superposed elements connected to each other via a continuous or discontinuous, longitudinal weld bead (14), which are formed by at least one longitudinal spacer (11) arranged beneath each of the longitudinal edges (21, 31) of the corresponding pair (A) of plates and by a corner cleat (12) arranged at the corners of said pair (A) of plates, the longitudinal edges (21-31) and the corners being fixed to said spacers (11) and said corner cleats (12) via a continuous weld bead (13) extending parallel to the direction of flow of the fluids.
2. Bank of plates according to Claim 1, characterized in that each pair (A) of plates is formed by an upper plate (10) and a lower plate (30), the longitudinal edges (21-31) of which are contiguous and the transverse edges (22-32) of which include at least one contiguous portion, at least one non-contiguous portion of said transverse edges (22-32) making at least one inlet and at least one outlet for one of said fluids and said contiguous portion of said transverse edges (22, 32) of each plate pair (A) making, with said contiguous portion, pairs (A) of plates adjacent to at least one inlet and at least one outlet for the other of the two fluids.
3. Bank of plates according to Claim 2, characterized in that said non-contiguous portion of each pair of plates is formed, on the one hand, by at least one recess (24) provided on the transverse edges (22) of the upper plate (20) and, on the other hand, by at least one recess (34) provided on the transverse edges (32) of the lower plate (30).
4. Bank of plates according to Claim 3, characterized in that the recesees (24-34) are located facing each other and oriented in an opposite direction in relation to the junction plane of the plates (20-30) of said pair (A) of plates.
5. Bank of plates according to Claims 3 and 4, characterized in that the recesses (24-34) are located substantially in the middle of said transverse edges (22-32).
6. Bank of plates according to any one of Claims 3 to 5, characterized in that the longitudinal edges (21) and at least one portion of the transverse edges (22) of the upper plate (20) define a first plane and the central portion (23) and the upper face (24a) of the recesses (24) of said upper plate define a second plane parallel to said first plane and in relief in relation to the latter.
7. Bank of plates according to any one of Claims 3 to 5, characterized in that the longitudinal edges (31), at least one portion of the transverse edges (31), and the central portion (33) of the lower plate (30) define a first plane, and the lower face (34a) of the recesses (34) of said lower plate defines a second plane parallel to said first plane and inset in relation to the latter.
8. Bank of plates according to Claim 7, characterised in that the longitudinal spacers (11) and the corner cleats (12) have a thickness corresponding to the gap between two adjacent pairs (A) of plates.
9. Bank of plates according to Claims 1 and 8, characterized in that the upper face of each longitudinal spacer (11) includes an outer rim (11a) delimiting a housing (11b) intended to receive the longitudinal edges (21-31) of the associated pair (A) of plates and of thickness substantially equal to the thickness of the plates (20-30) of said pair (A) of plates, said rim (11a) and said housing (11b) extending over the entire length of the spacer (11).
10. Bank of plates according to Claim 9, characterized in that the outer edge (11a) has a height substantially equal to the thickness of the plates (20-30) of the associated pair (A) of plates in order to form, with the upper face of the longitudinal edges (21-31) of said pair (A) of plates, a plane surface.
11. Bank of plates according to Claim 9, characterized in that the housing (11b) of each longitudinal spacer (11) includes, in the vicinity of the rim (11a), a groove (11c) intended to receive the possible burrs of the plates (20-30).
12. Bank of plates according to Claims 1 and 8, characterized in that the lower face of each spacer (11) includes a groove (11d) extending over the entire length of said spacer (11) for the positioning of the in-relief portion of the weld bead (13) of the adjacent pair (A) of plates.
13. Bank of plates according to Claims 1 and 8, characterized in that each corner cleat (12) is formed by two perpendicular branches and includes, on its upper face, an outer rim (12a) delimiting a housing (12b) intended to receive the corner of the associated pair (A) of plates and of thickness substantially equal to the thickness of the plates (20-30) of said pair (A) of plates.
14. Bank of plates according to Claim 13, characterized in that the outer rim (12a) has a height substantially equal to the thickness of the plates (20-30) of the associated pair (A) of plates in order to form, with the upper face of the longitudinal edges (21-31), a plane surface.
15. Bank of plates according to Claim 13, characterized in that the housing (12b) of each corner cleat (12) includes, in the vicinity of the rim (12a), a groove (12a) intended to receive the possible burrs of the plates (20-30).
16. Bank of plates according to Claims 1 and 8, characterized in that lower face of each corner cleat (12) includes a groove (12d) for the positioning of the in-relief portion of the weld bead (13) of the adjacent pair (A) of plates.
17. Bank of plates according to any one of the preceding claims, characterized in that each end of the non-contiguous portions of the transverse edges (22-32) of each pair (A) of plates is provided with an end cleat (15) connected to said plates (30) via a weld bead.
18. Method of assembling a bank of plates according to any one of Claims 1 to 17, characterized in that:

    - two plates (20-30) are superposed in order to form pairs (A) of plates, the longitudinal edges (21-31) and at least one portion of the transverse edges (22-32) of which are contiguous, at least one non-contiguous portion of the transverse edges (22-32) making at least one inlet and at least one outlet for one of the two fluids,

    - at least one longitudinal spacer (11) is arranged on the lower face of the transverse edges (21-31) and a corner cleat (12) is arranged on the lower face of the corners of each pair (A) of plates,

    - each pair (A) of plates is welded via a weld bead (13) to the spacers (11) and to the corner cleats (12) in order to hold the plates (20-30) in place,

    - end cleats (15) are installed at the ends of the non-contiguous portions of the transverse edges (22, 32) of each pair (A) of plates,

    - the contiguous portions of the transverse edges (22-32) and the end cleats (15) are welded to said transverse edges of the plates (20-30) of each pair (A) of plates,

    - a leaktightness that is carried out for each pair (A) of plates thus formed,

    - the pairs (A) of plates are superposed,

    - and the longitudinal spacers (11) and the superposed corner cleats (12) are welded via a continuous or discontinuous weld bead (14).
19. Plate heat exchanger including a vessel withstanding the internal pressure, in which vessel a bank (1) of plates according to any one of Claims 1 to 17 is placed.

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