GB2084712A

GB2084712A - Improvements in/or relating to plate heat exchangers

Info

Publication number: GB2084712A
Application number: GB8031328A
Authority: GB
Original assignee: APV Corp Ltd
Current assignee: SPX Flow Technology Crawley Ltd
Priority date: 1980-09-29
Filing date: 1980-09-29
Publication date: 1982-04-15
Also published as: GB2084712B

Abstract

In a plate heat exchanger comprising a pack of ported and gasketted plates 1 in face to face relationship to define flow spaces therebetween, at least one of the manifolds defined by aligned ports in the plates includes a restrictor 7 having two tabs or tongues 9 and a groove 11, which provide means for mounting the restrictor to one of each pair of plates. The restrictor can be constructed with a series of grooves 10 extending across the restrictor leaving a minimum of material thickness at the base of the groove. Strips of restrictor material can be removed in order to change the relative proportion of port area which is blocked off to that which is free. Thus, a high velocity of the medium passing through the port can be maintained. Solid or semi-solid material in the medium will thus be kept in suspension. The restrictor 7 can be made of an elastomeric material, for example, rubber, or it can be made from other materials, such as synthetic polymeric materials. <IMAGE>

Description

SPECIFICATION Improvments inlor relating to plate heat exchangers This invention relates to plate heat exchangers and to methods of operating them.

In plate heat exchangers the transfer of heat from one medium to another occurs as a continuous process, the two media flowing in substantially parallel flow spaces which are defined by a number of plates assembled in a face-to-face relationship.

The plates are constructed such that there is provision for the entry and exit of the media to and from the flow spaces formed by this plate relationship. For this purpose each plate may have four holes or ports, one at each corner, two of which allow a portion of one medium to enter, flow through and exit from the individual flow space, and the other two are sealed off from the flow space by a gasket such that the second medium is constrained to flow through these ports. A number of pack of plates is assembled with the ports is alignment to provide manifolds whereby the total quantity of medium which it is desired to heat or cool enters one of the manifolds and there is a continuous reduction in the quantity flowing through as portions of medium enter the successive alternate flow spaces. The second medium flows through the intervening flow spaces.The plates are normally mounted in a frame having flow connections aligned with the port manifolds for connection to external pipe work.

For reasons of design, the ports are all of the same size in any plate pack, and must be large enough to permit the entry of the whole quantity of the medium into the port manifold without undue energy loss, but as described the quantity flowing along the manifold is successively reduced until at the end opposite the entry the amount is reduced to the last portion of the medium which enters the last flow space, and consequently there is a reduction of velocity along the port manifold.

The entry and exit of liquid media to the port manifolds is normally arranged by providing connections of suitable size and position in the frame which is used to support and contain the plate pack, and these connections are aligned with the manifolds.

In certain processes it is desired to circulate liquid which contains solid or semi-solid matterthrough the heat exchanger. In some of these cases it has been found that the entry and exit ports of standard plates may be too large for the rate of flow whilst the remainder of the plate, that is the heat exchanging area, is ideally suited for the duty. In those cases where the velocity in the port areas is too low, there is a tendency for the solid or semi-solid material to come out of suspension and a deposit builds up in the port manifold.

It is the purpose of the present invention to overcome this by providing a means of modifying the port area to achieve the velocity conditions necessary for maintaining the solid or semi-solid material in suspension.

The present invention consists in a plate heat exchanger comprising a pack of plates in spaced face-to-face relationship to define close spaces therebetween and having manifolds for supply and discharge of fluid media to and from the flow spaces, wherein the manifolds for at least one of the media include a restrictor whereby the said at least one medium flows past the restrictor before entering the flow passage between adjacent plates so that solid or semi-solid material is inhibited from coming out of suspension.

Preferably, the restrictor is releasably secured in the manifold so that it can be removed therefrom without dismantling the pack of plates from the supporting frame.

Thus the area of the manifold is reduced by the installation of the restrictor which results in an increase in flow velocity along the manifold to inhibit the solid or semi-solid material from settling out of the medium, which is normally liquid.

The invention further consists in a restrictor for use with a plate heat exchanger comprising a pack of plates in spaced face-to-face relationship to define flow spaces therebetween and having manifolds for supply and discharge of fluid media to and from the flow spaces, which comprises a substantially twodimensional piece of material having means for mounting the'material in the manifolds of a plate heat exchanger.

Preferably, the restrictor comprises a substantially two-dimensional semi-circular piece of material having tabs at opposite sides of the material, such that the tabs provide means for mounting the material to a pair of plates in a plate heat exchanger. Thus a restrictor may be attached to each pair of adjacent plates in a plate pack to provide reduction of the flow area along the whole length of the port manifold.

The invention further consists in a method of operating a plate heat exchanger comprising a pack of plates in spaces face-to-face relationship to define flow spaces therebetween and having manifolds for supply and discharge of fluid media to and from the flow spaces, comprising passing one of the media through the manifolds, any number of the four manifolds having a restrictorwhereby solid or semi-solid material in the medium is inhibited from coming out of suspension.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa diagrammatic elevation of a single plate; Figure 2 is an enlarged section of the line Il-Il of Figure 1 of a number of plates assembled as a pack; Figure 3 shows a cross-section of the ports similar to Figure 2 with the addition of restrictors according to the invention; Figure 4 is an enlarged view of a port shown at the bottom right-hand of Figure la a restrictor being shown mounted in the port; Figure 5 is a schematic view of a restrictor according to the invention; Figure 6is a section on the line Ill-Ill of Figure 5; and Figure 7 is a schematic view of a restrictor according to the invention showing a cutting line W-W.

Figure 1 shows a plate 1 with entry and exit ports 2 and 3 for one medium, and gasketted through ports 4 and 5 for the other medium. A peripheral gasket 6 defines the flow space for one medium. Alternate plates in the pack are arranged so that entry ports 2 and 3 align with through ports 4 and 5 as seen in Figure 2. Also shown by Figure 2 is the relationship between medium flowing through the port manifold by way of the entry point at X and the continual reduction of flow volume in the port by drawing off of equal portions entering the flow passages 8 between plates at Y.

Figure 3 shows a cross-section of the ports similar to those in Figure 2 with the addition of restrictors 7.

Figure 3 also shows flow entry space 8 for a pair of plates.

Figure 4 shows an enlarged view of a port 2 shown atthe bottom right-hand corner of Figure 1.The port includes a restrictor 7. The restrictor 7 can be made of an elastomeric material, for example rubber, or it can be made from other materials, such as a synthetic polymeric material. The restrictor is usuailyformed in a moulding.

The thickness of the moulding is equal to the pitch of two plates when the plate pack is tightened and closed to the operating condition. When the pack is opened for maintenance purposes the plates must remain separable one from another in order to retain one of the technical merits of plate heat exchangers.

Thus the restrictor as described offers the advantages of installation with the plates, retention of plate separation, and modification of the manifold flow area along the whole length of the manifold for a plate pack of any size. Thus the alternative of installing a separate device into the port manifold after the plate pack is compressed, the need for securely locating such a device and above all making the device in numerous lengths for pack sizes ranging from a few to hundreds of plates is avoided.

The restrictor has two tabs or tongue 9 and a groove 11 (as shown in Figures 3 and 6), which provide means for mounting the restrictor to one of each pair of plates. In Figure 3, one tab 9 would locate in the space 8 associated with one plate whereas the groove 11 sits onto the edge of the plate in front. The flow area of the port 2 is thus reduced to that shown shaded in Figure 4. Thus, the restrictor reduces the port flow area, and thereby maintains a higher velocity of the medium passing through the port. Solid or semi-solid material in the medium will thus be kept in suspension.

The restrictor can be constructed with a series of grooves 10 as shown in Figures 5 and 6 leaving a minimum of material thickness at the base of the groove. This provides a ready means of successively removing strips of material by cutting for example along dotted line W-W (Figure 7) in orderto reduce the size of the restrictor. Thus it is an easy matter to change the relative proportion of port area which is blocked off to that which is free making it possible to vary the size of the restrictor along the length of the manifold to achieve optimum conditions of local velocity orto have different sizes of restrictor in different plate packs. The grooves 10 extend across the restrictors. A suitable number of these grooves is provided, so that strips of the restrictor material can be removed in order to change the relative proportion of port area which is blocked off to that which is free.

Figure 6 shows the restrictor having shallow sealing peaks 12. Each peak may only be 0.51 mm (0.02 in.) high. Thus, when the plate pack is compressed (as shown in Figure 3), each flow restrictor successively and positively seals on the back of an adjacent one.

Various other modifications may be made within the scope of the invention.

New claims or amendments to claims filed on 31.7.81.

Superseded claims 1-11.

New or amended claims:

Claims

CLAIMS 1. A plate heat exchanger comprising a pack of plates in spaced face-to-face relationship to define flow spaces therebetween and provided with aligned holes forming manifolds for supply and discharge of fluid media to and from the flow spaces, wherein the inlet manifold for at least one of the media includes a series of restrictors to increase the flow velocity so that solid or semi-solid material is inhibited from coming out of suspension in the manifold, and in which the restrictors are attached to individual plates so as effectively to reduce the cross-sectional area of the manifold. 2. A plate heat exchanger as claimed in claim 1, wherein a restrictor is releasably secured to one plate of each plate pair. 3. A plate heat exchanger as claimed in claim 1 or 2, in which the restrictors are formed to a common shape and are provided with readily removable portions to provide adaptability to different requirements. 4. A plate heat exchanger substantially as herein described with reference to and as illustrated in the accompanying drawings. 5. A restrictor for use with a plate heat exchanger comprising a pack of plates in spaced face-to-face relationship to define flow spaces therebetween and provided with aligned holes forming manifolds for supply and discharge of fluid media to and from the flow spaces, which restrictor comprises a substantially two-dimensional piece of material having means for releasable attachment to an individual plate so as partially to block the manifold forming hole. 6. A restrictor as claimed in claim 5, wherein the two-dimensional piece of material is semi-circular, the piece of material having tabs at opposite sides of the material, such that the tabs provide means for mounting the material to a plate in a plate heat exchanger. 7. A restrictor as claimed in claim 5 or 6, provided with readily removable portions to provide adaptability to different requirements. 8. A restrictor for use with a plate heat exchanger substantially as herein described with reference to and as illustrated in the accompanying drawings. CLAIMS (Filed on 9.10.80.)

1. A plate heat exchanger comprising a pack of plates in spaced face-to-face relationship to define close spaces therebetween and having manifolds for supply and discharge of fluid media to and from the flow spaces, wherein the manifolds for at least one of the media include a restrictor whereby the said at least one medium flows past the restrictor before entering the flow passage between adjacent plates, so that solid or semi-solid material is inhibited from coming out of suspension.

2. A plate heat exchanger as claimed in claim 1, wherein the restrictor is releasably secured in the manifold, so that it can be removed therefrom without dismantling the pack of plates from the supporting frame.

3. A plate heat exchanger as claimed in claim 1 or 2, wherein the area of the manifold is reduced by the installation of the restrictor, which results in an increase in flow velocity along the manifold to inhibit the solid or semi-solid material from settling out of the medium.

4. A plate heat exchanger as claimed in any one of the preceding claims, wherein the medium is liquid.

5. A plate heat exchanger as claimed in claim 1 and substantially as herein described with reference to and as illustrated in the accompanying drawings.

6. A restrictor for use with a plate heat exchanger comprising a pack of plates in spaced face-to-face relationship to define flow spaces therebetween and having manifolds for supply and discharge of fluid media to and from the flow spaces, which comprises a substantially two-dimensional piece of material having means for mounting the material in the manifolds of a plate heat exchanger.

7. A restrictor as claimed in claim 6, wherein the two-dimensional piece of material is semi-circular, the piece of material having tabs at opposite sides of the material, such that the tabs provide means for mounting the material to a pair of plates in a plate heat exchanger.

8. A restrictor as claimed in claim 6 or 7, wherein the restrictor can be attached to each pair of adjacent plates in a plate pack to provide reduction of the flow area along the whole length of the port manifold.

9. A restrictor for use with a plate heat exchanger as claimed in claim 6 and substantially as herein described with reference to and as illustrated in the accompanying drawings.

10. A method of operating a plate heat exchanger comprising a pack of plates in spaced face-toface relationship to define flow spaces therebetween and having manifolds for supply and discharge of fluid media to and from the flow spaces, comprising passing one of the media through the manifolds, any number of the four manifolds having a restrictor whereby solid or semi-solid material in the medium is inhibited from coming out of suspension.

11. A method of operating a plate heat exchanger as claimed in claim 10 and substantially as herein described with reference to and as illustrated in the accompanying drawings.