GB2107845A

GB2107845A - Plate heat exchanger

Info

Publication number: GB2107845A
Application number: GB08228336A
Authority: GB
Inventors: Johann Niemann
Original assignee: Schmidt W GmbH and Co KG; W SCHMIDT GmbH and Co KG
Current assignee: Schmidt W GmbH and Co KG; W SCHMIDT GmbH and Co KG
Priority date: 1981-10-16
Filing date: 1982-10-05
Publication date: 1983-05-05
Also published as: SE8205798D0; DE3141161A1; DK456882A; DE3141161C2; GB2107845B; FR2514880A1; SE8205798L

Abstract

The heat exchanger has heat exchange plates (33) which, in the case of at least one series of aligned inflow or outflow openings (28) over a part of the opening edge, are provided with collars (29) which are integral with the plate and which extend slightly obliquely with respect to the perpendicular to the plates and are formed in a straight or stepped manner. The collars of adjacent plates are positively nested one inside the other, thus forming the plate pack, so as to prevent transverse displacements between adjacent plates. <IMAGE>

Description

SPECIFICATION Plate heat exchanger The invention relates to a plate heat exchanger.

The invention is concerned more particularly with a heat exchanger of the type having heat exchange plates which are pressed out of sheet metal, are guided in alignment with one another in a frame, are clamped flatly against one another between a frame plate and a cover plate of the frame to form a stack and between which plate interspaces are formed which are closed by peripheral seals arranged on one side of each plate and which can be filled by way of aligned inflow and outflow openings, formed by plates, with the media involved in the heat exchange, in which, owing to an appropriate arrangement of the seals, each plate is in contact with one medium on one side and with another medium on the other.

Plate heat exchangers of this type, in which peripheral seals in the form of flat or profile seals are usually arranged in impressed peripheral grooves of the plates, are generally known. It is precisely on account of the attempt to overcome fairly high pressures and temperatures that they entail the problem that, owing to the high clamping forces required to press the plate pack closely together, individual plates tend to, or actually break out of the aligned compound arrangement. The reason for this lies in the fact that, owing to the inevitable manufacturing tolerances with respect to the frame, the plates and the seals disposed therebetween, a uniform introduction of clamping force over the periphery of the plates is impossible.This can result in forces which act on individual plates transversely to the clamping direction and which, in the case of high initial tensional forces, can increase to such an extent that the plates break out laterally with respect to the guide bars of the frame, thus damaging or destroying their guide. A further aggravating feature lies in the fact that the reaction forces which oppose the transverse forces and are transmitted from the guide bars to the plates give rise, in their turn, to frictional forces which act between the guide bars and individual plates and prevent the latter from moving on the guide bars when the plate pack is pressed together. These frictional forces, which oppose the tensional force, accumulate over the length of the plate pack when the plates are pressed together.They thereby increase the clamping forces, which are in any case necessary, and thus again increase the danger of individual plates breaking out. Finally, the surface of the seals and seal faces are often coated with a parting compound, which reduces the friction between the seal and the seal face, in order to prevent the seals becoming stuck. This is particularly likely to cause the plates to break out if, in order to overcome fairly high pressures and temperatures, correspondingly high clamping forces are introduced into the plate pack.

In order to counter the problems described above, it has already been proposed, according to Federal Republic of Offenlegungsschrift 27 13 977, to provide the plates with cams which project in the manner of a bead in the region of the leakage space next to the inlet and outlet openings and engage positively in the corresponding concave recesses of the adjacent plates, thus tending to prevent a mutual lateral displacement of adjacent plates.

However, the disadvantage of this type of construction is that, on one hand, with regard to the space available for their arrangement, the interlocking cams and recesses can only have relatively limited dimensions, as a result of which their effectiveness is also limited. On the other hand, the frame with the projecting cams must also be provided with corresponding recesses, which increases the cost of the construction.

According to the invention there is provided a plate heat exchanger with heat exchange plates which are pressed out of sheet metal, are guided in alignment with one another in a frame, are clamped flatly against one another between a frame plate and a cover plate of the frame to form a stack and between which plate interspaces are formed which are closed by peripheral seals arranged on one side of each plate and which can be filled by way of aligned inflow and outflow openings, formed by the plates, with the media involved in the heat exchange, in which, owing to an appropriate arrangement of the seals, each plate is in contact with one medium on one side and with another medium on the other, wherein, in the case of at least one aligned series of inflow or oufflow openings formed by the plates, the opening edge is provided over a part of its circumference with at least one collar piece, which is integrally formed on, extends slightly obliquely with respect to the perpendicular to the plate surface and is formed in a straight or stepped manner, and wherein the outer contour thereof is in positive engagement with the inner contour of the collar of the plate which follows in its direction.

It is advantageous for the collar to extend essentially over the part of the opening edge which is remote from the plate interspace. In this case the collar is disposed between the peripheral seal and the opening, so that it does not obstruct the flow of the respective medium from the opening into the plate interspace and therefore cannot constitute a flow barrier.

These measures make it possible, in an extremely simple and inexpensive manner, to provide adjacent plates with a mutual closing shape, without this entailing additional expenditure on material and manufacture. This is because, when the plates are manufactured, the collar can be formed in a simple manner with the plates by being pressed out of a sheet by using an appropriately shaped form tool. The collar surfaces of adjacent heat exchange plates which are thus formed and are in positive engagement with one another are several times greater than the plate guide surfaces adjacent the guide bars, on account of the size of the inflow and outflow openings in the plates, so that they also distribute to a plurality of plates considerable transverse forces acting on individual plates, while avoiding high surface pressures, and can thus prevent individual plates from breaking out.

Furthermore, the use of the collar results in an increase in the size of the opening cross section, without the necessity of tolerating a loss in stability at the opening edge, which is usually reinforced by forming corrugations or beads.

The collars of the heat exchanger plates and the connecting pieces arranged in the frame can also be formed in a simple manner such that the collar(s) of the heat exchange plate directly adjacent the frame or pressure plate project(s) into the connecting pieces, thus rendering additional recesses in the frame unnecessary.

Finally, the use of the collar cannot have a detrimental effect on the seal between adjacent plates, as it does not surround the entire opening edge and can thus yield resiliently to a slight extent within necessary limits.

When providing several series of openings with collars, it is advantageous for these series to be arranged either symmetrically to an axis of symmetry of the plates or symmetrically to the central point of the plates. This accordingly results in symmetrical conditions, even with respect to holding forces opposing the transverse forces, so that a unilateral distortion of the plate pack cannot occur.

Finally, the edges of the collars can comprise bead-like bulges, which are open towards the centre of the opening. In this construction the collars of adjacent plates only contact one another in the region between the bulges, while connecting ducts are formed between the openings and the cavities between the collar and the adjacent seal. A turbulent media exchange to cavities can continuously take place by way of these connecting ducts, so that no dirt deposits or the like can form at this point.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of a known plate heat exchanger; Figure 2 is a detail of a known heat exchange plate; Figure 3 is a sectional view along the broken line Ill-Ill in Figure 2; Figure 4 is a detail of one embodiment of heat exchange plate according to the invention; Figure 5 is a sectional view along the broken line V-V of Figure 4; Figure 6 is a detail of another embodiment of a heat exchange plate according to the invention; and Figure 7 is a sectional view along the broken line VIl-VIl of Figure 6.

Referring to Figure 1, the known plate heat exchanger shown therein comprises a frame with a frame plate 1 and a support 2, which are connected together at the top and the bottom in the longitudinal direction by guide bars 3 and 4 by way of nuts 5. Heat exchange plates 6 are inserted between the guide bars 3 and 4 and are clamped together to form a pack by a cover plate 7 in a finally assembled plate heat exchanger, as shown in part 8. Tightening screws 9 with nuts 8, which are passed through openings 11 in the frame plate 1 or openings 12 in the cover plate 7 past the heat exchange plates, are to clamp the plates.

In the illustrated example the frame plate 1 comprises four connecting pieces 13, which are in alignment with corresponding inflow and outflow openings in the heat exchange plates 6, and seals 14 are arranged alternately such that one medium flows to the heat exchanger by way of a duct 15, then flows along the plate interspaces associated with this medium along the arrow 16 and finally flows away again by way of the duct 17, while the other medium flows in through the duct 18, flows along the plate interspaces associated with this medium along the arrow 19 and finally flows away again by way of the duct 20.

Figure 2 is an enlarged detail of the upper right-hand end of one of the plates 6 of Figure 1.

In this known heat exchange plate the opening 21 which serves to supply the medium is externally surrounded by the peripheral seal 22, so that the medium entering or leaving through this opening has a connection in the direction of the arrow 23 to the plate interspace disposed on the left-hand side below the opening. The edge of the opening 21 is reinforced in a known manner by profiles 24. Further details concerning the way in which the plate is shaped or stamped will not be provided, as this is known. It should simply be noted that the recess through which the plate according to Figure 2 is positively engaged with the guide bar 3 according to Figure 1 is shown in part at 25.

Figure 3 is a sectional view along the line 111- Ill of Figure 2. This figure shows how several plates 6 are arranged next to one another and the plate interspaces 26 formed by the latter are externally closed off or sealed by the peripheral seals 22 disposed in plate grooves 27.

Figures 4 and 5 are views corresponding to Figures 2 and 3 of a first embodiment of a heat exchange plate according to the invention. The particular features of this plate, in as far as they correspond to those-of the known heat exchange plate, will not be described in detail.

However, the plate according to Figures 4 and 5 differs from the known plates in that a collar 29 is formed onto the opening 28 when the plate is manufactured by stamping or pressing, extends essentially over the arc of the opening 28 which is remote from the plate interspace and, as shown particularly in Figure 5, is formed in a stepped manner and extends slightly obliquely to the perpendicular onto the plate such that the collars 29a to 29c of adjacent plates positively interlock in that their outer contour 30a to 30c in each case comes to rest against the inner contour 31 a and 31 c of the adjacent collar. The reference number 32 again designates the peripheral seal, which has not, however, been altered in any way with respect to the known one.

As shown in particular in Figure 4, in comparison with the known plate according to Figure 2, the collar 29 is formed, without any additional expenditure on material, from the material which at this point forms the profile 24 for reinforcing the opening edge. The flow cross section for the opening 28 is thereby enlarged and no loss has to be tolerated as regards the reinforcement of the opening edge.

Figures 6 and 7 show a heat exchange plate 34 which has been modified with respect to Figures 4 and 5. In Figures 6 and 7 the collar 35 is provided with beads 37 which project into the opening 36 and which form ducts 38, through which medium can flow into the cavities 39 between the plates 34 and the seals 40, so that no deposits can form at this point.

As is particularly evident from Figures 5 and 7, the oblique arrangement of the collars should be undestood as a stepped inclination or undulatory offset arrangement. It is essential for adjacent collars to nest one inside the other in a positive manner, without thereby preventing the formation of the seal between adjacent heat exchange plates.

In other respects it is self-evident that the collars described in connection with Figures 2 to 7 with reference to a plate opening can also be provided on all or several aligned plate openings, in which case, however, a symmetrical formation with respect to an axis of symmetry of the heat exchange plates, or the centre thereof, is advantageous. This naturally applies irrespective of the plate form illustrated in the examples and the position in the latter of the openings, as the subject matter of the invention can likewise be used in heat exchange plates of a different construction with a corresponding different position of the inflow and outflow openings for the media.

Claims

1. A plate heat exchanger with heat exchange plates which are pressed out of sheet metal, are guided in alignment with one another in a frame, are clamped flatly against one another between a frame plate and a cover plate of the frame to form a stack and between which plate interspaces are formed which are closed by peripheral seals.

arranged on one side of each plate and which can be filled by way of aligned inflow and outflow openings, formed by the plates, with the media involved in the heat exchange, in which, owing to an appropriate arrangement of the seals, each plate is in contact with one medium on one side and with another medium on the other, wherein, in the case of at least one aligned series of inflow or outflow openings formed by the plates, the opening edge is provided over a part of its circumference with at least one collar piece, which is integrally formed on, extends slightly obliquely with respect to the perpendicular to the plate surface and is formed in a straight or stepped manner, and wherein the outer contour thereof is in positive engagement with the inner contour of the collar of the plate which follows in its direction.

2. The plate heat exchanger of Claim 1, wherein the collar extends essentially over the part of the opening edge which is remote from the plate interspace.

3. The plate heat exchanger of Claim 1 or Claim 2, wherein, when several series of openings are provided with collars, these series of openings are arranged either symmetrically to an axis of symmetry of the plates or symmetrically to the central point of the plates.

4. The plate heat exchanger of any one of the preceding claims, wherein the edges of the collars have bead-like bulges which are open towards the centre of the opening.

5. A plate heat exchanger substantially as hereinbefore described with reference to, and as shown in, Figures 4 and 5 or Figures 6 and 7 of the accompanying drawings.