US3548933A - Plate heat exchangers - Google Patents

Description

I Unlted States Patent [111 3,548,933

[ 72] lnventor Kenneth Lindsay Rain [56] References Cited m A l N Enahnd UNITED STATES PATENTS E ff No 15 1968 2,934,321 4/1960 Hytte 165/167X [4s] Patented Dec. 31366 gecker 165/166X 1 l 67 impelaar.... 165/166X [731 3:2: 3,322,189 5/1967 Topouzian 165/166 [32] Priority Nov. 17,1967 Primary Examiner-Robert A. OLeary [33] Great Britain Assistant Examiner-Theophil W. Streule [31] No. 52386/67 Attomey-Stevens, Davis, Miller & Mosher ABSTBQC'I): Piste heat elilrchangeri are proposed, which are essentra y ase upon t e use 0 portless heat exchange [54] f fiffgggg plates. The inlet and outlet connections are provided by ducts, preferably of channellike shape, which are slotted into or [52] US. 165/167 otherwise applied to the edges of the plates, the Sealing means [51] Int. F28!) 3/00 between the plates underneath these ducts being omitted at [50] Field of Search 165/166, selected locations to provide passageways into and out from the spaces between adjacent plates.

PLATE near axcnxnosns This invention relates to plate heat exchangers. It is conventional practice to form heat exchangers from an assembly of thin and generally similar plates, which are arranged in sideby-side relationship and are spaced from one another by sealing gaskets or other sealing means. It is obviously desirable to use the largest possible proportion of the total area of each plate for the transfer of heat and many different proposals have been made and adopted in the past for arranging the plates and their, gaskets so as to achieve satisfactorily efficient operation.

Plate heat exchangers can be regarded as having three types of use. These are evaporation, in which the'material undergoing treatment (usually referred to as the productf) is heated so as to change from the liquid to the vapor phase, condensation, in which the reverse effect takes place and a product initially in the vapor phase is deprived of heat so that it changes to the liquid phaserand liquid/liquid exchange, in which both the product and the heat transfer fluid remain in the liquid phase throughout. In evaporation processes, it is often necessary to evaporate a liquid using low pressure water vapor as the heating medium. The vapor volumes encountered are much greater than the volumes in liquid/liquid heat exchange. The pressure drop progressively increases with throughput, lowering the effective temperature difference across the plates and severely affecting the capacity of the system. Thus for an effective evaporation process, larger port sizes are needed than are provided in standard plates. The heat transfer fluid, i.e. the material used to carry out the desired treatment on the product, can be either liquid phase or vapor phase in evaporation and is almost always in the liquid phase in condensation The usual arrangement in a plate heat exchanger provides that one of the materials, e.g. the product passes into the exchanger at one end or corner of the plates, down between the first pair of plates, through ports into the space between the second pair of plates and so on, whilst the other materials, e.g. the heat transfer fluid, passes in the opposite sense and between the adjacent plates of each two consecutive pairs of plates. Heat exchange plates need to fulfill a large number of requirements, with respect to heat transfer, self-supporting ability, thinness and so on, and are relatively expensive to make. It is thus desirable to form an exchanger from plates which are as similaras possible and desirably are identical so with four ports at the corners, as is illustrated for example in Specification No. 935542.

' It is an object of the invention to avoid the expense of the manufacturing operations involved in forming ports in plates, the loss of efficiency caused by insufficiently uniform contact of the materials with all of the part of the area of the plates available for heat exchangeand the cther'disadvantages inherent in the manufacture and use of heat exchangers comprising ported plates.

The arrangement exchanger of the present invention comprises a plurality .of spaced plates and separably attached channellike ducts running the length of the assembled plates for supplying and removing a fluid to be heated and a heating fluid; It is often of advantage, according to a particular feature of the invention, if the exchanger is assembled from plates which are rectangular. Thisprovides a generally blocklike or cuboidal shape of heat exchanger, having header members or end plates clamped at either end of the set of plates (with their associated gaskets or ability, sealing arrangements); the chan- The ducts for one fluid preferably are located along opposite sides of the assembly of plates It is alpo preferable for the ducts for the other fluid to be located along the same side of the assembly of plates.

In order that the invention may be readily understood, preferred embodiments thereof are described below in conjunction with the accompanying drawings, given by way of illustration only, wherein: l 1 Q 1 FIG. I shows in diagrammatic perspective view one form of portless plate heat exchanger of the invention;

FIG. 2 shows in exploded diagrammaticperspective view number of plates as they are arranged in a heat exchanger of the kind illustrated by FIG. 1;

.FIG. 3 shows a detail of a plate similarly to the views of plates included in FIG. 2;

FIG. 4 shows a cross section taken on the line lV-IV in FIG.

FIG. 5 shows in diagrammatic perspective view an alternative embodiment to the plate shown in FIG. 2; V

P FIG. 6 shows, in a similar diagrammatic perspective view to that of FIG. 5, a third form of plate;

FIG. 7 shows a fourth embodiment of a plate;

FIG; 8 shows a detail of a heat exchanger formed from plates of the kind illustrated in FIG. 7

FIG. 9 shows a detail of the edges of a number of adjacent plates, havingaparticular form of sealing gasket;

FIG. It) shows a detail of a fifth form of plate having a connecting member in the form of a welded modular duct portion;

FIG. II shows a cross section on the line XI-XI of F IG. 10;

FIG. 12 shows a diagrammatic perspective view of a heatexchanger formed of plates of the kind shown in FIGS. 10 and l l.

FIG. .1 of the accompanying drawings shows an example of a complete heat exchanger. A plurality of plates 1 are clamped together by means of pressure heads 2 and bolts 3. A duct 4 is provided at the top of the heat exchanger into one end of which the product is introduced via a conduit 5. A similar duct 4' and outlet conduit 5' for the product are provided at the bottom of the heat exchanger and an-inlet conduit 6, an outlet conduit 7 and ducts 8 and 9 are provided for the heating fluid.

FIG. 2 is an exploded view of six plates of the heat exchanger, the various plates being indicated by reference nu-- merals la, lb, 1c, Id, lie and If.

The ducts 4', 8 and 9 arechannel members'of rectangular configuration open at one side and have flanges 10 which fit into L-shaped slots II in the edges of the plates la to l f. Gaskets 12, through which the slots 11 also extend, surround the periphery of one side of each plate 1a to l f except between the slots 11 in the top and bottom of the plates la, 10 and le and in the side of the plates lb and 1d, the width of the gap being dependent upon the purpose for which the plate is to be used. The product and the heating fluid flow through these gaps which are held open by means of corrugated spacers such as those shown in FIG. 3, which are attached to the plates by, for example spot welding. This arrangement allows a single type of plate to be manufactured for both the product channels and the heating fluid channels. Alternatively the surface of the plates in the gaps may be corrugated.

' Preferably, the plates the ducts and the spacers are made of stainless steel or titanium.

The flow of path of the product is indicated by the arrows 23 and the flow path of the heating fluid by broken arrows 24 in FIG. 2. Thus, the product flows along the top duct 4, down the channel between the plates la and lb, into the bottom The heating fluid flows from the duct 8, into the channels between the plates lb and 1c, and Id and 1e, and out into the duct 9.

FIGS. 5 and 6 show an alternative method of fitting ducts of rectangular and arcuate configuration into the edges of the plates 1. Instead of the walls of the ducts having the flanges 10, they have cylindrical beads 18 at their edges which fit into circular or keyhole-shaped apertures 19 having neck portions 20 extending to the edges of the plate.

A further and simpler method of fitting the ducts to the plates is shown in FIGS. 7 and 8 which are a view of a single plate and a side view of part of a heat exchanger assembly respectively. In FIG. 7, a plate I and the associated gasket 12 are provided with indentations 30 into which fit the cylindrical beads 18 of a duct 31. As shown in FIG. .8, the duct is held in position and sealing effected by members 32 which force the duct 31 against the plates 1. The members 32 are threaded in a bar 33 which runs the length of the heat exchanger and which is fixed to the end plates 2 of the exchanger. Ducts of the type shown in FIG. 2 may also be fitted to the plates by this method, in which case no indentations are needed in the plate edges.

The method described with reference to FIGS. 7 and 8 of fitting the ducts to the plates, allows the type of gasket shown in FIG. 9 to be used. As shown in FIG. 9, the edges of the plates are bent through a right-angle to form flanges 41, and gaskets 40, which may be formed from extruded strip, are fitted by being forced over the flanges 41. The gaskets are then cut away to form the entrances and exits of the product and heating fluid channels.

FIG. 9 also shows a method of retaining the corrugated spacers 14 in position. The spacers 14 are connected in pairs, a connecting bridge piece or member 42 resting on an intermediate plate. Referring to FIG. 2, the spacers associated with plates 1c and 1e can be connected in this manner, the connecting member resting on the plate 1d.

FIG. of the drawings shows a partial view of a portless heat exchanger plate 50. A gasket 51, for sealing the space between the plate 50 and an adjacent plate when they are assembled into a heat exchanger, extends around the periphery of the plate 50 except for a portion of the plate, which in this example is in the vicinity of the corner. To provide for the supply or removal of fluid in the absence of ports in the plate, a striplike portion 52 of plate material is fixed in the form of a loop to the edge of the plate 50 at the corner portion by, for example, welding to form a connecting duct 53. The loop is formed, as shown in FIG. 1 so that the portion 52 extends the gasket 51 at the top edge of the plate 50, then follows a semicircle and returns in a straight portion to the side edge of the plate 50, where it connects with the gasket 51 in a rightangled joint.

As shown in F 1G. 10 and in FIG. 11 which is a sectional view along line Xl-Xl of FIG. 10, the striplike portion 52 consists of a continuous channel of U-shaped cross section. A gasket 54 is fitted into the channel and is joined to the gasket 51.

The arrangement of the gasket 51 in the vicinity of the duct 53 depends on whether or not the medium flowing through the duct 53 also passes down the face 55 (FIG. 10) of the plate 50. If this is the case, the arrangement of the gasket 51 is as shown by the solid lines in FIG. 10. However, if the medium passing through the duct 53 is to be prevented from passing down the face 55, as is the case with every other plate in the pack forming the exchanger, a further gasket 56 is needed as shown by the dotted lines in FIG. 10. The arcuate comer portion of the plate 50 is preferably correspondingly channeled so that the gasket 56 is housed in a channel having a section like that shown at 52 in FIG. 11.

FIG. 12 of the drawing shows an assembled evaporator made up of plates each having an external manifold 57 formed from the series of ducts 53 provided in corresponding locations on the respective plates as shown in FIGS. 10 and II and gasketted accordingly. The plates are held together in the normal manner b bolts (not shown) passin through end plates 58 and 58'. he end plates 58 and 5 are provide with manifold portions 59 and 59', corresponding to the external manifold 57, to effect sealing between the individual plates of the manifold. The end plate 58 has an aperture 60 therein which is aligned with and provides communication to the elementary duct members of the individual plates.

The connection members constituted by the ducts 53 can, of course, have many different shapes from that shown in FIGS. 10 and 12. It is, of course, possible to vary the effective areas of the ducts 53 to suit particular requirements.

I claim:

I. A plate heat exchanger which comprises a plurality of plates assembled in side-by-side relationship and spaced from one another to form a plurality of fluid-flow channels, two pairs of ducts running the length of the assembly of plates, one pair of ducts for supplying and removing a fluid to be heated and the other pair of ducts for supplying and removing a heating fluid, the ducts being in the form of opensided channelshaped members and being secured to the edges of the plates in sealing relation therewith, with the open side facing the plates, a sealing gasket surrounding the periphery of one side of each plate to space the plates from one another, an aperture in each gasket beneath each duct of one of said pairs of ducts and means for blocking the ducts for the fluid to be heated in at least every other of said plates whereby the fluid to be heated is constrained to flow between a pair of adjacent plates from the supply to the removal duct, past the next space between the plates in the removal duct and then between the next pair of adjacent plates from the removal duct to the supply duct; the heating fluid flowing in the space between the plates past which the fluid to be heated passes.

2. A plate heat exchanger according to claim I, in which the ducts have flanged edges which are fitted into slots formed in the plates.

3, A plate heat exchanger according to claim 1, in which the ducts have beaded edges which are fitted into slots formed in the plates.

4. A plate heat exchanger according to claim 1, in which the edges of the ducts are urged into contact with recesses formed in the plates.

5. A plate heat exchanger according to claim 1, in which the ducts are of rectangular cross section.

6. A plate heat exchanger according to claim 1, in which the apertures are provided with corrugated spacers.

7. A plate heat exchanger according to claim 1, having plates which are rectangular.

8. A plate heat exchanger according to claim 6, in which the ducts for fluid to be heated are located along opposite sides of the assembly of plates.

9. A plate heat exchanger according to claim 6, in which the ducts for the heating fluid are located along the same side of the assembly of plates.

10. A plate heat exchanger according to claim I, in which the blocking means consist of baffle plates attached to the edges of the plates and provided with a sealing grommet extending across the duct.

11. A plate heat exchanger according to claim 9, in which the baffle plates are connected in pairs by a connecting bridge which passes across the intermediate space.

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