CA1262891A - Method of manufacturing a metal lining and a metal lining manufactured according to the method - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention discloses a method of manufacturing a metal lining for a plate heat exchanger and a metal lining manu-factured according to this method. The method comprises plastic machining of a smooth plate such that a cylindrical part and at least one edge flange is formed. The metal lining comprises at least one cylindrical part and at least one but preferably two flanges.

Description

9~
The present invention relates to a method of manufactur-ing a metal lining for use in plate heat exchangers and a metal lining manufactured according to the method.
A plate heat exchanger comprises a plurality of heat exchanger plates which are fastened between a frame plate and a pressure plate. In this connection a good contact is required bet-ween the frame plate andJor the pressure plate and the closest heat exchanger plate. In the frame plate and/or the pressure plate there are inlet holes and outlet holes for passage of the heat exchanging media. These media can be corrosive and, therefore, corrode non-alloy steel. There is, however, a wish to manufacture the frame plate and/or the pressure plate of a material which is as cheap as possible and which as a rule does not resist corrosive media. This has been solved by a lining, for instance of metal, which has been inserted into the inlet ports and the outlet ports of the frame plate and/or the pressure plate. The lining resists the corrosive medium that goes through the inlet ports and the out-let ports.
When using metal linings the basic material has previously been a cylinder on which has been fastened a flange by welding on each side of the hole of the frame plate and/or the pressure plateO
In order to be able to weld the flanges on the cylinder the thick-ness of the material should be at least 3mm. Such a metal lining has, however, not been able to be directly applied to the side surface of an unmachined frame plate, because it would have meant that the distance between the frame plate or the pressure plate and the closest heat exchanger plate becomes unacceptably large. For this reason each frame plate and/or pressure plate that has been provided with a meta:L lining has had to be machined such that a recess for the flanges of the lining is provided at the connection holes on each side of the plate. Such a machining is both expensive and time-consuming and requires expensive equipment. Moreover, the Bg~L

welding of the flanges onto the cylinder, which working Per se is also both time-consuming and expensive, involves unacceptable cracks being introduced into the weld such that the lining has to be re~ected or a new weld has to be made. Thus, control measures are an essential feature of the welding procedure, which raises the price of the metal linings still more. These disadvantages taken together have made conventional metal linings too expensive to manufacture and use.

The present invention provides for the manu-facture and use of metal linlngs which are cheaper and accordlngly make increased use possible.

According to the present invention there is provided in a plate heat exchanger comprising a frame plate and a pressure plate forming end plates, a pack of heat exchange plates positioned between said end plates and forming passages for separate flows of two heat exchanging media, at least one of said end plates having holes for conducting said media -to and from respective passages in said pack, means for compressing said pack between said end plates, and linings for said holes, said linings being of a metal more corrosion-resistant than said end plates, the improvement wherein each said lining includes a hollow cylinder in said hole, a first flange having a thickness substantially less than 3mm, a seamless connection to one end of the cylinder and sealingly compressed between an ad;acent heat exchange plate and an undepressed surface on one side of said end plate, which surface surrounds said hole, and a second flange connected to the other end of the cylinder and opposing an undepressed surface on thé other side of said end plate.
Suitably said second flange has a seamless connection to said other end of the cylinder. Preferably said second flange has a welded connection to said other end of the cylinder. Desirably said .~

~ ~6 ~
thickness is no greater than 1 mm.
In one embodiment of the present invention at least one heat exchange plate forms with an ad;acent end plate a thin intervening space containing a plurality of said first flanges operable to prevent leakage of said heat exchanging media into said space. Desirably both of said end plates have holes each provided with a said lining.
The present invention further provides an end plate for use as a frame plate or pressure plate of a plate heat exchanger, said end plate having holes for conducting a heat exchanging medium and extending between opposite side surfaces of the plate, each said surface being substantially planar whereby each end of each hole is surrounded by a flat unde pressed surface, a hollow cylinder in each hole for lining the same, a first flange having a seamless connection to one end of each cylinder and engaging a said undepressed surface, and a second flange connected to the other end of each cylinder and opposing another undepressed surface.
In a further aspect thereof the present invention provides a method of lining a connection port for fluid in a frame plate member or pressure plate member of a heat exchanger having heat exchange plates, said plate member hav-ing opposite side surfaces which are undepressed around said port, said method comprising the steps of plastically deform-ing a metal disc into a hollow cylinder having a flange pro-jecting outwardly from one end of the cylinder, engaging said flange with one of said undepressed side surfaces by inserting the other end of the cylinder directly into said port while both ends of the cylinder are open, and securing the cylinder against withdrawal from the port by providing the cylinder with a second outwardly projecting flange engaging the other of said undepressed side surfaces.

?;~
~ ~- 2a -g~
In another aspect thereof the present lnvention pro-vides a method of lining a connection opening for fluid in a frame plate of a plate heat exchanger, characterized in that said frame plate has an lnside surface, an outside surface and an undepressed area about the connection opening on each side surface of the plate, in that a pipe socket wi-th a diameter corresponding to the diameter of the opening is provided with a flange of thin sheet metal, with a thickness of at maximum 1 mm., and is placed in the opening with the flange abutting the undepressed area about the opening on the inside surface of the plate with a socket portion pro;ecting on the outside of the plate, and in that said socket portion is provided with a flange to abut the undepressed area about the opening on said outside surface of the plate. Suitably the pipe socket is beaded out at one end prior to the attachment of the socket in the opening, with the flange abutting the undepressed area about the opening on one side of the plate. Desirably the flange on the inside surface of the frame plate is clamped sealingly between said plate and the plate member in the plate heat exchanger which is located closest to the frame plate.
In a still further aspect thereof the present inven-tion provides a method of lining a connection opening for fluid in a frame plate of a heat exchanger, said frame plate having an inner surface facing an ad~acent heat exchanger plate and an outer surface facing outwardly of the heat exchanger and being of uniform thickness, said surfaces being planar and said opening having inner and outer edges lying in the planes of said inner and outer surfaces without there being any area of reduced plate thickness surrounding said opening, said method comprising fitting into the opening a metal pipe socket having~an outside diameter corresponding to the diameter of the opening and having inner and outer end .. ;~

~ - 2b -~2~g~
flanges whlch abut said lnner and outer surfaces of sald plate and which thereby project outside the planes of said surfaces, said inner flange being formed of thin sheet metal of 1 mm.
maximum thickness.
The present invention again provides a method of forming the lining in which a metallic plate is plastically machined such that a hollow open ended cylinder with at least one edge flange is formed.
The manufacturing method according to two preferred embodiments of the invention will be described with reference to the accompanying drawings, in which:-Figure 1 illustrates the basic material for manufac-turing the metal lining;
Figure 2 illustrates the situation after a first working moment;
Figure 3 illustrates the situation after a second working moment;
Figure 4 illustrates the lining inserted into a frame .~ I

- 2c -~ ~6 ~
plate with the second flange shown with broken lines;
Figure 5 illustrates a second embodimen-t of a rnetal lining inser-ted into a frame plate, and Fig. 6 is a schematic side view, partly in section of a plate heat exchanger in which holes in the frame and pressure plates are provided with metal linings according to the invention.
When manufacturing a metal lining the basic material is a smooth, thin metal plate of suitable quality, preferably in the form of a round, the thickness of which is less than 3mm and preferably lmm or less. This pla-te is plastically machined, preferably by deep drawing, pressure rolling and/or pressing, such that a cylindrical pot 20 with edge flange 21 (see Fig. 2) is formed. From this pot 20 the bottom is then removed to form an open cylinder 30 with an edge flange 31.
sefore the cylinder 30 is inserted into the frame plate and/or the pressure plate heat treatment is effected if it is deemed to be necessary. Then the cylinder is placed in the frame plate and/or the pressure plate 40 with its edge flange 41 towards one side 42 of the plate. So that the cylinder is able to act as an effective lining a flange is also made on the cylinder on the other side 43 of the plate 40. This is effected by flanging out a part of the cylinder 30, whereby a flange 44 is formed on -the other side 43 of the plate. The flanging is preferably effected by pressure rol-ling and/or pressing.
In this method the basic material is an unholed plate in the form of a round, which is formed to a cylindrical pot from which the bottom is removed. It is, however, also possible to start with a holed plate, for instance a round provided with a hole. In this case an open cylinder with edge flange is directly formed when machining the plate.

~, .. . .

~ ~289~
The metal lining is provided with flanges -that are not fastened by means of welding but have been machined out of the basic material. Due to that fact the lining can be made of a very thin pla-te whlch ~ se makes the manufac-ture of the lining cheaper. I~he most important advan-tage with the thin lining, however, is that the side walls of the frame plate and the pressure plate do not need to be machined for the flanges of the lining, which as has been mentioned previously is a very expensive operation. These flanges become so thin that they can be pu-t on the outside of the side walls of the frame plate and/or the pressure plate.
The metal lining is preferably designed such that the cylinder section in a plane essentially parallel with the flange/Elanges is circular or elliptical.
In Fig. 5 there is illustrated an alternative embodiment of the invention. In this case the metal lining comprises two parts 51/52 fastened to each other, preferably by means of welding. In this connection each part comprises a cylindrical part with an edge flange resting against respec-tive side of the frame plate 50. The parts 51,52 are prefer-ably manufactured by means of deep drawing, pressure rolling and/or pressing of a smooth plate in a similar way as disclo-sed in Fig.s 1-3. The advantage with this embodiment is that for given dimensions on the parts 51,52 the metal lining by moving the parts 51,52 to or from each other previous to the welding procedure can be used in frame plates and/or pressure plates of different sizes.
As previously mentioned, the frame plates and/or pressure plates of prior plate heat exchangers have required machining side surfaces thereof to provide recesses located at the holes for the heat exchanging media and which receive flanges welded to the ends of the cylinders of prior metal .. -- "., .
~ 4 -~L~6~8~, linlngs. Otherwise, the flanges would resul-t in an unaccept-ably large distance between the frame plate or pressure plate and the closest heat exchange plate. With the present inven-tion, however, when the plates of t;he heat exchanger are clam-ped together in the usual manner, and especially when the metal has the above~mentioned preferred maximum thickness of lmm, the flange 41 of each open cylinder or pipe socket 30 can be clamped sealingly between this closest hea-t exchange plate and an undepressed area of plate 40 shown in Fig. 4.
This clamping of the plates is illus-trated in Fig.
6, where the heat exchanger comprises a frame 60 carrying a frame plate 61 and a pressure plat.e 62. Between these plates is a pack of heat exchange plates 63, of wh.ich only those near the plates 61 and 62 are shown. sy conventional means, such as threaded rods 64 and bolts 65, the heat exchange plates 63 are sealingly pressed together between plates 61 and 62. The latter have inlet and outlet holes 66 for conducting the two heat exchanging media to and from their respective passages between adjacent heat exchange plates. Each hole 66 is lined with a metal lining 67 applied as shown in Fig. 4. Thus the flanges 67a at opposite ends of each lining have seamless connections with the hollow cylindrical part of the lining.
It will be understood that the heat exchange plate 63 at each end of the pack is pressed firmly against flanges 67a lying against the adjacent plate 61 or 62. secause of the limited thickness of these flanges, as noted above, they not only provide a very thin space between each of plates 61 and 62 and the adjacent heat exchange plate 63 but also form effective seals against leakage of the heat exchanging media into these spaces.
The heat exchanger of Fig. 6 requires external ducts (not shown) connected to each end plate 61 and 62 for conduct-.. . - 5 -- . --~.~Z62~39~

ing -the hea-t exchanging media to and from the respec-tive pas-sayes between pla-tes 63 via m~tal linings 67. If desired, however, -the ducts for this purpose may be connected to only one of the plates 61 and 62 which is provided with all of -the metal linings 67, as will be readi:Ly understood by those skil-led in the art.

.~ - 6 -~ .

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a plate heat exchanger comprising a frame plate and a pressure plate forming end plates, a pack of heated exchange plates positioned between said end plates and forming passages for separate flows of two heat exchanging media, at least one of said end plates having holes for conducting said media to and from respective passages in said pack, means for compressing said pack between said end plates, and linings for said holes, said linings being of a metal more corrosion-resis-tant than said end plates, the improvement wherein each said lin-ing includes a hollow cylinder in a said hole, a first flange having a thickness substantially less than 3 mm, said flange hav-ing a seamless connection to one end of the cylinder and being sealingly compressed between an adjacent heat exchange plate and an undepressed surface on one side of said end plate, which sur-face surrounds said hole, and a second flange connected to the other end of the cylinder and opposing an undepressed surface on the other side of said end plate.

2. The improvement of claim 1, in which said second flange has a seamless connection to said other end of the cylin-der.

3. The improvement of claim 1, in which said second flange has a welded connection of said other end of the cylinder.

4. The improvement of claim 1, 2 or 3, in which said thickness is no greater than 1 mm.

5. The improvement of claim 4, in which at least one heat exchange plate forms with an adjacent end plate a thin intervening space containing a plurality of said first flanges operable to prevent leakage of said heat exchanging media into said space.

6. The improvement of claim 5, in which both of said end plates have holes each provided with a said lining.

7. The improvement of claim 2, in which each said lin-ing is entirely seamless.