EP0495184B1 - Plate type heat-exchanger with counter-current flow - Google Patents

Abstract

The invention relates to a plate heat exchanger for media conducted in counterflow, consisting of shape-embossed individual plates (1) which are connected to one another to produce a pair (P) of plates forming a flow duct for one medium and which for their part are connected to produce a plate stack (S) and in each case form between themselves a flow duct for the other medium. The supply and discharge cross-sections of each duct are diagonally offset with respect to one another in the longitudinal direction of the plate. In order to achieve a reliable seal between the individual plates (1), each individual plate (1) is constructed in each case adjoining and parallel to its rims (12) which extend in the longitudinal direction of the plate and on which it is connected to the adjacent individual plate (1) to produce a pair (P) of plates with a bearing surface (13) which is offset with respect to the rim (12) by half the height of a pair (P) of plates and on which the individual plates (1) of adjacent pairs (P) of plates are connected to one another. <IMAGE>

Description

The invention relates to a plate heat exchanger for countercurrent media, consisting of shaped single plates, which are connected to one another to form a flow channel for the plate pairs forming a medium, which in turn are connected to form a plate stack and each form a flow channel for the other medium, whereby the inflow and outflow cross-section of each channel is offset diagonally to one another in the longitudinal direction of the plate, and the inflow and outflow cross-sections of the channels for the two media lie next to one another, but are offset by half the height of the inflow and outflow cross-section of the channels.

Such plate heat exchangers, which correspond in principle to the plate heat exchangers known from DE-A-37 10 823, are used for example in environmental technology and can also be designed for large volume flows of the media involved in the heat exchange, whereby these media need not only be gaseous media, since there are cases in which the heat exchange between liquids or between a gas and a liquid should take place.

In the case of plate heat exchangers of the type described in the introduction, in which the individual plates connected to form a plate pair form a flow channel for one medium between them and the plate pairs connected to form a stack form a flow channel for the other medium between them, the problem of reliable sealing arises both the individual panels together to form pairs of panels (sealing type 1) as well as the plate pairs with each other to the plate stack (sealing type 2). Since both types of sealing are decisive for the tightness of the flow channels of the two media flowing in countercurrent to one another, the problem of sealing increases when one or both media are under pressure and / or there is a pressure difference between the two media. The problem of sealing is further exacerbated by the fact that such a plate heat exchanger is exposed to high temperatures and, in some cases, considerable temperature differences between the two media participating in the heat exchange, these temperature influences being intensified particularly when the heat exchanger is started up.

Particularly when such plate heat exchangers are used in environmental technology, it is often made more difficult that the individual plates must have a more or less great resistance to corrosion. The individual plates are therefore made of plastic or stainless steel; Furthermore, versions made of normal steel sheet are known, but this is provided with a corrosion protection layer made of plastic or enamel. While single plates made of plastic or stainless steel can be welded together with a higher technical effort, this is not possible with single plates provided with a corrosion protection layer without destroying this protective layer in the area of the weld seams. In the known plate heat exchangers, a different type of connection must be selected here, for example gluing or clamping, preferably with the interposition of seals.

The invention has for its object to develop a plate heat exchanger of the type described in such a way that a reliable and permanent seal both between the individual plates and between the plate pairs, taking into account the above-mentioned temperature stresses with little technical and manufacturing effort results.

The solution to this problem by the invention is characterized in that each individual plate is formed in connection with and parallel to its edges running in the longitudinal direction of the plate, at which it is connected to the adjacent individual plate to form a pair of plates, with a contact surface which is opposite the edge is offset by half the height of a pair of plates and at which the individual plates of adjacent plate pairs are connected to one another, and that the individual plates forming a plate stack at their transverse edges lying in the region of the inflow and outflow of the two media are at a partial length with the individual plate belonging to the plate pair and are connected over the remaining part length to the single plate of the adjacent plate pair.

By designing such contact surfaces according to the invention, it is also possible in series production in a simple manner to reliably and permanently connect both the individual plates to plate pairs and the plate pairs to form a plate stack, it also being possible to first connect in the area of the contact surfaces according to the invention and only then make the connection on the longitudinal edge of the individual panels. There are defined contact surfaces between the individual plates for both connections, so that a seal that is tailored to the respective application and to the plate material can always be selected. Furthermore, there are two rows of side-by-side inflow and outflow openings for the media guided in countercurrent to one another. The configuration according to the invention is also suitable for individual plates provided with a corrosion protection layer.

The openings formed by the height-offset contact surfaces in the inflow and outflow region of the plate stack are closed according to a further feature of the invention, so that there is a technically simple supply and discharge of the media flowing through the plate heat exchanger on opposite sides of the plate stack.

The plate pairs and / or the individual plates can, according to the invention, be welded to one another and / or sealed together at their contact surfaces or edges. The gas or liquid-tight connection can therefore not only be achieved by welding or gluing, i.e. done positively, but also non-positively in that the individual plates of the plate stack are pressed against each other, preferably by using tie rods and end plates. Both in the form-fitting connection, i.e. by welding or gluing, as well as in the non-positive connection of the individual plates, it can be advantageous to provide suitable seals in the area of the edges and / or contact surfaces. The same type of connection is preferably selected in the area of the transverse edges to be connected. However, it may also be sufficient to effect the connection of the individual plates in the region of their transverse edges due to the dimensional stability of the individual plates as a result of their connection at the longitudinal edges and contact surfaces solely by inserting seals.

If the individual plates are made of plastic or stainless steel, it is proposed according to a further feature of the invention to connect the individual plates to one another at least on their longitudinal edges and contact surfaces by roll seam welding. If coated individual plates are used to form the plate stack, according to the invention these can be uncoated at the longitudinal edges and can therefore be welded to one another here. In both cases, it is possible to insert seals between the individual plates in addition to the welding.

With the invention it is further proposed that the individual plates or plate pairs of a plate stack on the longitudinal and To connect transverse edges and on the contact surfaces with each other, preferably by means of tie rods running between end plates. This results in a particularly simple preparation and assembly of a plate stack for the plate heat exchanger according to the invention.

Finally, it is proposed with the invention to form recesses for receiving seals or sealing compound in the area of the contact surfaces and / or the longitudinal edges and / or the transverse edges. Such groove-like depressions simultaneously increase the dimensional stability of the individual plates.

Normally, the inflow and outflow cross-section of the channels will be the same for the two media participating in the heat exchange, in particular if the volumes of the two media participating in the heat exchange approximately correspond to one another. In this case - with the same predetermined height of the inflow and outflow openings - the width of these openings formed by the transverse edges of the individual plates is the same. The inflow and outflow cross sections of the two different channels through which the two media flow in countercurrent can also have a different size if the volume flows of the two media participating in the heat exchange differ greatly from one another. In this case, the inflow and outflow cross sections formed by the transverse edges of the individual plates have a different width at the same height. In order to adapt the entire flow channel course to these different inflow and outflow cross sections, differently shaped single plates are used, so that following the inflow and outflow cross sections, differently high flow channels result for the two media flowing in counterflow. In this case there is the disadvantage that the plate stack can no longer be formed from individual plates of a single type, which are twisted only about their longitudinal axis to form the plate stack and are produced with a single tool will. On the other hand, the higher manufacturing effort, which requires two different tools for embossings of different depths, has the advantage that the plate heat exchanger according to the invention can also be used with great success if two media with different volume flows take part in the heat exchange.

Fig. 1

eine perspektivische Ansicht eines Plattenstapels für ein erstes Ausführungsbeispiel des Plattenwärmetauschers,

Fig. 2

eine Teilansicht der Stirnseite des Plattenstapels nach Fig. 1,

Fig. 3

eine Draufsicht auf ein Plattenpaar eines Plattenwärmetauschers einer zweiten Ausführungsform,

Fig. 4

eine Ansicht der einen Stirnseite des Plattenpaares nach Fig. 3,

Fig. 5

eine Ansicht der anderen Stirnseite des Plattenpaares nach Fig. 3,

Fig. 6

einen Querschnitt durch das Plattenpaar nach Fig. 3 gemäß der Schnittlinie VI - VI in Fig. 3 und

Fig. 7

eine perspektivische, schematische Darstellung eines Plattenwärmetauschers aus Plattenpaaren gemäß den Fig. 3 bis 6.

Two exemplary embodiments of a plate heat exchanger according to the invention are shown in the drawing, namely:

Fig. 1

2 shows a perspective view of a plate stack for a first exemplary embodiment of the plate heat exchanger,

Fig. 2

2 shows a partial view of the end face of the plate stack according to FIG. 1,

Fig. 3

a plan view of a plate pair of a plate heat exchanger of a second embodiment,

Fig. 4

3 shows a view of one end face of the plate pair according to FIG. 3,

Fig. 5

3 shows a view of the other end face of the plate pair according to FIG. 3,

Fig. 6

a cross section through the plate pair of FIG. 3 along the section line VI - VI in Fig. 3 and

Fig. 7

a perspective, schematic representation of a plate heat exchanger from plate pairs according to FIGS. 3 to 6.

The first exemplary embodiment shown in FIGS. 1 and 2 shows schematically and in perspective the plate stack S of a plate heat exchanger, which is otherwise not shown, for media conducted in countercurrent. This plate stack S consists of a plurality of identical, shaped individual plates 1, which are each connected to form a plate pair P.

Each individual plate 1 comprises a base 11 which lies in a different plane from the longitudinal edges 12. In connection and parallel to these longitudinal edges 12, each individual plate 1 is each formed with a contact surface 13 which is offset in height from the longitudinal edges 12. The offset between the contact surface 13 and the associated longitudinal edge 12 is twice as large as the offset between the longitudinal edges 12 and the bottom 11; the bottom 11 is therefore located in the middle between the plane of the longitudinal edges 12 and the plane of the contact surfaces 13.

The edges extending transversely to the longitudinal edges 12 of the single plate 1 are approximately half in the embodiment of FIGS. 1 and 2 in the plane of the longitudinal edges 12 and in the plane of the contact surfaces 13. In this way, there are transverse edges 14a and 14b, which in height, ie perpendicular to the surface of the base 11 are offset from one another by the same amount as the planes in which the longitudinal edges 12 on the one hand and the contact surfaces 13 on the other hand. As can be clearly seen in FIG. 1, the transverse edges 14a and 14b lie diagonally opposite one another.

From the above-described individual plates 1 shown in the upper part of FIG. 1, plate pairs P are formed according to the lower representation in FIG. 1 by connecting a single plate 1 to a single plate 1 rotated about its longitudinal axis at the longitudinal edges 12. 1 and 2, five complete plate pairs P₁ to P₅ are shown, with a single plate 1 being arranged on the uppermost plate pair P₅ and another single plate 1 is located at a greater distance above this single plate 1 arranged on the plate pairs P.

If the plate pairs P are now connected in the area of the contact surfaces 13 to form a plate stack S, there are alternately superimposed channels in which flow flows in the opposite direction for the two media participating in the heat exchange. While one medium flows in the channels which are formed by the plate pairs P, the other medium flows in the channels which result from the joining of the plate pairs P to the plate stack S. The lying in the plane of the longitudinal edges 12 transverse edges 14a of the individual plates 1 here form the inlet openings E₁ and the outlet openings A₁ of the channels for the medium flowing between the plate pairs P. The extending in the plane of the contact surfaces 13 transverse edges 14b of the individual plates 1 form the inlet openings E₂ or the outlet openings A₂ for the other medium which flows between the individual plates 1 of each pair of plates in the opposite direction. As can be seen again in Fig. 1, are due to the diagonal arrangement of the inlet and outlet openings, the inlet openings E₁ for the first medium next to the outlet openings A₂ for the other medium, each offset by half a height of a pair of plates P.

The front view shown in Fig. 2 of the left part of the plate stack S shown in perspective in Fig. 1 shows that the plate pairs P₁ to P₅ can be produced in a simple manner in that the individual plates 1 are connected together at their longitudinal edges 12. The connection of the plate pairs P created in this way to a plate stack S takes place in an equally simple manner in that adjacent individual plates 1 of the plate pairs P are connected to one another in the region of the abutting contact surfaces 13. In a corresponding manner, the transverse edges 14a and 14b of adjacent individual plates 1 are connected in accordance with FIG. 1.

With such an assembly of the individual plates 1 to form a plate stack S, lateral openings O result on each end face of the plate stack S, each of which is connected to the flow channel which is formed by the individual plates 1, which are connected to form a plate pair P, for the one medium. In order not to complicate the supply and discharge of this one medium, these openings O are closed in a suitable manner.

In the first exemplary embodiment according to FIGS. 1 and 2, the individual plates 1 lie flat on one another both in the region of their longitudinal edges 12 and in the region of their contact surfaces 13. The connection of the individual plates 1 can be done in a simple manner by welding, preferably roller seam welding. Such a roll seam welding can be carried out not only in the case of individual plates 1 made of plastic or stainless steel, but also in the case of individual plates 1 provided with a corrosion protection layer, if these individual plates 1 are uncoated in the outer region of their longitudinal edges 12, so that they are welded here without destroying the corrosion protection layer can be. In this case, however, it is necessary to connect the individual plate pairs P to a plate stack S in a different way.

The assembly of a plate stack S from individual plates 1 by welding can be simplified in that adjacent individual plates 1 are welded together first in the area of their contact surfaces 13 and only then in the area of their longitudinal edges 12. In this case, at least one roller seam weld can be carried out in a particularly simple manner in the area of the contact surfaces 13 and longitudinal edges 12. Of course, however, it is also possible to first connect the individual plates 1 to plate pairs P by means of roller seam welding in the area of their longitudinal edges 12 and then the plate pairs P to weld to a plate stack S by making fillet welds between the superimposed contact surfaces 13.

In the second embodiment according to FIGS. 3 to 6, modified individual plates 1 are used. These are provided with groove-like depressions 15 both in the region of their longitudinal edges 12 and transverse edges 14a and 14b and in the region of their contact surfaces 13. These recesses 15 form cavities for receiving a sealant or seals 2. Such seals 2 can be used not only in addition to welding the individual plates 1 on their contact surfaces, but also as an alternative to such welds if the individual plates 1 of a plate stack S are on others Be sealed together with their contact surfaces. 7 shows, using a schematic exemplary embodiment, that the plate stack S can also be formed in that the individual plates 1 are clamped between a base plate 3 and a cover plate 4 with the aid of tie rods 5. In this case, welding of the individual plates 1 to plate pairs P or welding of adjacent plate pairs P to one another can be dispensed with.

3 to 6 that the flow cross section of a channel, which is created by a pair of plates P formed from two individual plates 1, is almost constant over the length of the channel. 4 and 5, which show the end views according to the arrows IV and V in Fig. 3, show that the cross section of the inlet opening E₁ and the cross section of the outlet opening A₁, which are diagonally opposite, are approximately the same size. This flow cross section also results in the channel profile lying between the inlet opening E 1 and the outlet opening A 1, which is shown in FIG. 6. In this area, the channel has half the height of the inlet opening E₁ or outlet opening A₁, but the full width. In this way, undesirable flow losses when flowing through the plate stack S are avoided. A corresponding channel structure also results for those channels which are formed by adjacent plate pairs P.

4 and 5 finally show that the openings O resulting from the additional contact surfaces 13 in the end faces of the plate stack S can be closed in a simple manner. In the embodiment according to FIGS. 3 to 6, plugs 6 are shown which are inserted into these openings O. Of course, the openings O can also be closed in a different way, for example by welding or pressing.

While in the two exemplary embodiments shown in the drawing, the transverse edges 14a and 14b of the individual plates 1 are of approximately the same size, so that there are approximately the same size inlet and outlet openings for the two media flowing in countercurrent, it is of course also possible to use a different one Volume flow of the two media participating in the heat exchange to take into account by changing the ratio of the lengths of the transverse edges 14a and 14b to each other. In order to achieve a channel cross-section that is as uniform as possible over the channel length in this case as well, the distances between the planes in which the contact surfaces 13, the bottoms 11 and the longitudinal edges 12 lie must also be changed in accordance with the length ratio of the transverse edges 14a and 14b. In this case, however, it is necessary to use two differently shaped individual plates 1 to build up a plate stack S.

From the above explanations and the drawings it follows that 1 compact modules for plate heat exchangers can be produced with the individual plates described, whose individual plates due to their edge stability and dimensional accuracy create the necessary conditions to design such plate heat exchangers for countercurrent media for high operating pressures and for aggressive media.

Reference symbol list:

1

Single plate

11

ground

12th

Longitudinal edge

13

Contact surface

14a

Cross border

14b

Cross border

15

deepening

2nd

poetry

3rd

Base plate

4th

Cover plate

5

Tie rod

6

Plug

S

Plate stack

P

Plate pair

E₁

Entry opening medium 1

A₁

Outlet opening medium 1

E₂

Entry opening medium 2

A₂

Outlet opening medium 2

O

opening

Claims (8)

1. Plate heat exchanger for media conveyed in counterflow, consisting of embossed individual plates (1) which are connected to one another to form pairs of plates (P) which form a flow channel for one medium and which are themselves connected to form a plate stack (S) and form between them a respective flow channel for the other medium, the inflow and flow-off cross-section of each channel being offset diagonally relative to one another in the longitudinal direction of the plates, and the inflow and flow-off cross-sections of the channels for the two media being located next to one another, but offset by half the height of the respective inflow and flow-off cross-section of the channels, characterized in that each individual plate (1) is designed, contiguously with and parallel to its edges (12) which extend in the longitudinal direction of the plates and at which it is connected to the adjacent individual plate (1) to form a pair of plates (P), with a respective bearing face (13) which is offset relative to the edge (12) by half the height of a pair of plates (P) and at which the individual plates (1) of adjacent pairs of plates (P) are connected to one another, and in that the individual plates (1) forming a plate stack (S), at their transverse edges (14a, 14b) located respectively in the inflow and flow-off region for the two media, are connected over a part length to the individual plate (1) belonging to the pair of plates (P) and over the remaining part length to the individual plate (1) of the adjacent pair of plates (P).
2. Plate heat exchanger according to Claim 1, characterized in that the orifices (O), formed by the bearing faces (13) offset in height, are closed in the inflow and flow-off region of the plate stack (S).
3. Plate heat exchanger according to Claims 1 and 2, characterized in that the pairs of plates (P) and/or the individual plates (1) are welded to one another and/or connected in a sealed-off manner to one another at their bearing faces (13) or edges (12, 14a, 14b).
4. Plate heat exchanger according to at least one of Claims 1 to 3, characterized in that the individual plates (1) are connected at at least their longitudinal edges (12) and bearing faces (13) by roll-seam welding.
5. Plate heat exchanger according to at least one of Claims 1 to 3, characterized in that, when coated individual plates (1) are used, the longitudinal edges (12) are uncoated and are welded to one another.
6. Plate heat exchanger according to Claim 4 or 5, characterized in that, in addition to the welding, seals (2) are inserted between the individual plates (1).
7. Plate heat exchanger according to at least one of Claims 1 to 6, characterized in that the individual plates (1) or pairs of plates (P) of a plate stack (S) are connected to one another at the longitudinal and transverse edges (12, 14a, 14b) and at the bearing faces (13) non-positively, preferably by means of tie rods (5) extending between end plates (3, 4).
8. Plate heat exchanger according to at least one of Claims 1 to 7, characterized in that depressions (15) for receiving seals (2) or a sealing-off mass are formed in the region of the bearing faces (13) and/or of the longitudinal edges (12) and/or of the transverse edges (14a, 14b).

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