US3201332A

US3201332A - Plate heat exchanger

Info

Publication number: US3201332A
Application number: US180155A
Authority: US
Inventors: Wennerberg Fritz Johan
Original assignee: Separator AB
Current assignee: Alfa Laval Holdings Amsterdam AB
Priority date: 1962-03-16
Filing date: 1962-03-16
Publication date: 1965-08-17
Anticipated expiration: 1982-08-17

Description

g 1955 F. J. WENNERBERG 3,201,332

PLATE HEAT EXCHANGER 2 Sheets-Sheet 1 Filed March 16, 1962 INVENTOR. FR TZ (J IAN M ENNER GER G- W W A TTORN Eys 1965 F. J. WENNERBERG 3,201,332

PLATE HEAT EXCHANGER Filed March 16, 1962 2 Sheets-Sheet 2 Farr:- Jot-(km M/EHNERBERQ- BY 9 Ml $11M Y A TT'DR N E 5 United States Patent 3,201,332 PLATE HEAT EXCHANGER Fritz Johan Wennerberg, Lund, Sweden, assignor to Ahtiebolaget eparator, Stockholm, Sweden, a corporation of Sweden Filed Mar. 16, 1962, Ser. No. 180,155 9 Claims. (Cl. 202- 172) The present invention relates to heat exchangers of the plate type for concentrating a liquid by evaporation or for condensing a vapor, or for both. More particularly the heat exchanger of this invention is of the type having a series of vertically disposed plates between which are formed heat exchange chambers for a heat-emitting medium which alternate with heat exchange chambers for a heat-absorbing medium.

Conventional plate heat exchangers are entirely closed .and include loose plates of pressed, thin sheet metal provided with passages (usually four) for the media taking part in the heat exchange. Experience "has shown that these passages cannot be made large enough to keep acceptably low the pressure drop in the passages for the voluminous vapor. Too great a pressure drop in the passages for the vapor means an impaired heat economy of the apparatus, which should be avoided.

According to the present invention this problem is solved by providing a plate heat exchanger of the type mentioned in which the heat exchange chambers of the one kind are sealed all along their edges while the heat exchange chambers of the other kind are sealed only to such an extent that they are open at their upper edges, where they open into a housing which encloses the plates. In theopen heat exchange chambers, the vapor produced during the evaporation is discharged through the upper open edges of the chambers, which edges form a large discharge area for the vapor. Due to the fact. that the plates are enclosed in the housing, the vapor is caught in the latter, so that there will be no trouble with leaking connections to the chamber openings.

' The sealing of the chambers may be effected in the conventional manner by means of resilient gaskets, such as rubber gaskets, or by welding all the plates together, or by welding them together in pairs and inserting rubber gaskets between adjacent plate pairs. in this way the closed chambers can be sealed by welding and the open chambers by means of rubber gaskets, or conversely.

One embodiment of the present heat exchanger, which can be used to particular advantage for producing fresh water from brine, is characterized in that the heat exchanger comprises one evaporator section and one condenser section and that the open heat exchange chambers of both sections communicate with each other through the housing. In such an apparatus, concentrated brine leaves the evaporator chambers and boiled-off steam flows from the same chambers into the condenser chambers, where the steam condenses on the cooled chamber walls and is discharged as condensate water through a discharge outlet in the chamber bottoms. The condensate thus obtained constitutes the desired fresh water. This embodiment of the apparatus can also be used for other distillation processes.

The passing of the vapor from the evaporator section to the condenser section is preferably ensured by providing a common housing enclosing both sections, which may consist of separate plate units. In such an embodiment the liquid outlets of the evaporator chambers may open into the housing proper, the bottom of which in that case is provided with an outlet for evaporated liquid. By a common housing is meant a closed housing of any suitable form. I

in order to prevent pollution of the condensate by splashes of the liquid being evaporated, a splash-guard such as deflection screens, separating such liquid from the vapor, is preferably provided in the path which is discharged vapor takes in passing from the evaporator section to the condenser section.

A way to increase further the flow area for the vapor flowing out of or into the open heat exchange chambers is to let the upper edge of each such chamber constitute a longitudinal side of the chamber. Another arrangement, which also increases the same flow area, is to make the distances between the plates which form the open heat exchange chambers larger than the distances between the plates forming the closed heat exchange chambers.

Though the above-mentioned evaporator and condenser sections can bev arranged separately beside or above each other, it is also possible, in a simpler embodiment requiring less space, to build them together in a single plate unit by means of a common clamping device.

A relatively large number of open as well as closed heat exchange chambers are arranged in a heat exchanger of high capacity. The open chambers are connected in parallel and together form what may be referred to as a pocket with a high evaporating or condensing capacity. The closed chambers can also be connected in parallel but if the heating or cooling capacity of a certain quantity of heating or cooling medium is to be used in the best possible way, it is preferable to connect the closed chambers in series.

The housing may be thermally insulated in order to increase the efficiency of the plant or to avoid a dilution of the evaporated liquid (collected in the housing) with condensate from the housing walls.

In the evaporator section, evaporated liquid can discharge from the open chambers by flowing out through the upper openings of the chambers. The evaporated liquid is then collected at the bottom of the housing. However, of each of the open chambers (open at the top) of the evaporator section is provided with a separate liquid inlet and a separate liquid outlet, the entire discharge capacity of the openings at the upper edges of the chambers can serve for discharging the vapor.

In order that the present invention may be better understood, there will now be described various embodiments thereof, given by way of example only, reference beinghad to the accompanying drawings in which:

FIGS. 1 and 2 are face views of adjacent plates of 3 brine) is assumed to enter via a corner passage 4 into the chamber 2 surrounded by the gasket 3 and to be discharged through an opposite corner passage 5. The flow direction can, however, be the reverse. A liquid to be evaporated flows in through a corner passage 6 and along the back of the plate and is discharged therefrom through an opposite corner passage 7. The passages 6 and 7 are surrounded by gaskets 8 and 9. It is assumed that a plate 10, shown in FIG. 2, rests with an intervening gasket 11 against the back of the plate 1. This gasket 11 defines a heat exchange area 12 along the lower edge and the shorter sides of the plate. No gasket is, however, provided along the upper edge 13 of the plate 10. Therefore, the heat exchange chamber 12 is open upward so that the vapor evaporated from the chamber can be discharged through a passage 14, which thus extends along the upper edge of the plate. It the chamber 12 is used to condense vapor, the latter can flow in through the same passage 14 and condense on the walls of the chamber. In this case the condensate is discharged through a lower corner passage 15. If the chamber 12 is used for evaporating purposes, the liquid to be evaporated fiows in through the passage 15 and the concentrate is discharged through an opposite lower corner passage 16 which is provided for that purpose. In order to prevent the passage 14 from becoming unnecessarily throttled when clamping the plate unit, the plate 19 is provided with spacing lugs 17 along its upper edge 13 in the area of the passage 14. When the plate unit is clamped, these spacing lugs bear upon the plate 1 and maintain the desired distance between the upper edges of both plates. The passages 15 and 16 correspond to the passages 6 and 7 in the plate 1. Likewise the passages 18 and 19 in the plate 10 correspond to the passages 4 and in the plate 1. The passages 18 and 19 are surrounded by gaskets 20 and 21.

FIGURES 3 and 4 show another embodiment of the plates 1 and wherein the flow over the heat exchange surfaces runs along the longitudinal direction of the plate instead of diagonally, as in the embodiment according to FIGURES l and 2. In FIGURES 3 and 4 the corresponding parts are designated by the same reference numerals as in FIGURES l and 2, but with the subscript a added.

In FIGURE 5, reference numeral 22 designates a frame plate which carries two heat exchange sections 23 and 24-, of which the first one constitutes an evaporator and the second one a condenser. Both sections are hermetically enclosed by means of a hood 25 screwed onto the plate 22 by means of bolts 26. The heat exchange sections are provided with

end pieces

27 and 28, respectively. The plates of each section 23-24 are clamped together by means of bolts 29 and carried and guided at each end by a guiding bolt 30. On its way to the upper edge of the condenser section 24 the vapor discharged at the upper edge of the evaporator section 23 meets a splash-guard comprising deflection plates 31. The liquid splashes which accompany the vapor are caught on these deflection plates and then trickle down to the bottom of the hood 25, to be discharged therefrom through an outlet 32. All evaporated liquid may be allowed to discharge as splashes from the section 23.

In FIGS. 5 and 6 it is assumed that plates according to FIGURES 1 and 2 are used, these plates alternating with each other. As shown in FIG. 6, the holes for the bolts 26 in the plate 22 are designated by the reference numeral 33. The heating medium enters the evaporator section 23 through a pipe 34 and is discharged through a pipe 35. The liquid to be evaporated enters section 23 through a pipe 36 and is discharged through a pipe 37. The pipe 37 can, if desired, be replaced by an outlet (not shown) leading inside the hood 25 so that the evaporated liquid can be pumped out through the outlet 32 together with the collected splash liquid. The cooling medium enters in the condenser section 24 through a pipe 38 and is discharged therefrom through a pipe 39. The vapor to be condensed enters at the upper edge 13 of the condenser section and is pumped out as condensate through a pipe 40. When producing fresh water from brine in the device according to FIGURES 5 and 6, consideration must be given to the fact that the container 22-25 should be maintained at a considerable under-pressure in relation to the atmospheric pressure if hot water is to be used as heating medium, e.g. Waste water from the machinery of a ship.

I claim:

1. In a plate heat exchanger, the combination of a series of generally vertical heat exchange plates disposed in substantially parallel adjacent relation, first gasket means compressed between the opposing plates of each alternate pair of said plates and extending continuously along the marginal portions of said opposing plates to define therewith a closed heat exchange chamber surrounded by said gasket means, second gasket means compressed between the opposing plates of each of the other pairs of said plates and extending continuously along the marginal portions of said last opposing plates except along the upper portions thereof, whereby said other pairs of plates define with the intervening open gasket means second heat exchange chambers which are open along their upper edges but closed along their bottom and side edges, said plates having throughfiow passages and coacting gaskets forming an inlet to and a separate outlet from each of said closed chambers and also forming an outlet leading from each of said open chambers between the open upper edge and the closed bottom edge thereof, and means forming a housing enclosing said plates and into which said open chambers open along said upper edges thereof.

2. The combination according to claim 1, in which said plate passages and gaskets also form an inlet leading to each of said open chambers and which is separate from said outlet from each open chamber.

3. The combination according to claim 1, in which said plates are generally rectangular and in which said upper edges are formed by longer sides of the plates.

4. The combination according to claim 1, in which said housing is provided with a bottom discharge outlet.

5. In a plate heat exchanger, the combination of a series of generally vertical heat exchange plates disposed in substantially parallel adjacent relation, first gasket means compressed between the opposing plates of each alternate pair of said plates and extending continuously along the marginal portions of said opposing plates to define therewith a closed heat exchange chamber surrounded by said gasket means, second gasket means compressed between the opposing plates of each of the other pairs of said plates and extending continuously along the marginal portions of said last opposing plates except along the upper portions thereof, whereby said other pairs of plates define with the intervening open gasket means second heat exchange chambers which are open along their upper edges, said series of plates and gasket means forming an evaporator section having separate inlets for a heating medium and a liquid to be evaporated leading, respectively, to said closed and open chambers, said section also having an outlet leading from said closed chambers, a condenser section comprising plates and gasket means similar to said plates and gasket means of said evaporator section, the condenser section having a cooling medium inlet leading to said closed chambers of the condenser section and also having separate outlets leading, respectively, from said closed and open chambers of the condenser section, and means forming a housing enclosing the plates of at least one of said sections and into which said open chambers of said one section open along said upper edges thereof, said open chambers of the respective sections being in communication with each other through said open upper edges thereof and the interior of the housing.

6. The combination according to claim 5, in which said housing encloses the plates of both sections.

7. The combination according to claim 5, in which said housing encloses the plates of both sections. vided with a bottom discharge outlet.

8. The combination according to claim 5, comprising also a liquid-vapor separator disposed in said housing in the path of said communication.

9. The combination according to claim'5, in which the housing means include a housing plate forming inlet and outlet connections for the respective sections, the combination comprising also means for clamping the plates and gasket means of the respective sections together against the housing plate.

References Cited by the Examiner UNITED STATES PATENTS 745,921 12/03 Stade 159-28 881,523 3/08 Winter 159-17 2,562,739 7/51 Risberg 15928 2,788,065 4/57 Lockman 159--20 2,960,160 11/60 Goodman 159-28 CHARLES SUKALO, Primary Examiner.

ROBERT A. OLEARY, Examiner.

Claims

1. IN A PLATE HEAT EXCHANGER, THE COMBINATION OF A SERIES OF GENERALLY VERTICAL HEAT EXCHANGE PLATS DISPOSED IN SUBSTANTIALLY PARALLEL ADJACENT RELATION, FIRST GASKET MEANS COMPRESSED BETWEEN THE OPPOSING PLATES OF EACH ALTERNATE PAIR OF SAID PLATES AND EXTENDING CONTINUOUSLY ALONG THE MARGINAL PORTIONS OF SAID OPPOSING PLATES TO DEFINE THEREWITH A CLOSED HEAT EXCHANGE CHAMBER SURROUNDED BY SAID GASKET MEANS, SECOND GASKET MEANS COMPRESSED BETWEEN THE OPPOSING PLATES OF EACH OF THE OTHER PAIRS OF SAID PLATES AND EXTENDING CONTINUOUSLY ALONG THE MARGINAL PORTIONS OF SAID LAST OPPOSING PLATES EXCEPT ALONG THE UPPER PORTIONS THEREOF, WHEREBY SAID OTHER PAIRS OF PLATES DEFINE WITH THE INTERVENING OPEN GASKET MEANS SECOND HEAT EXCHANGE CHAMBERS WHICH ARE OPEN ALONG THEIR UPPER EDGES BUT CLOSED ALONG THEIR BOTTOM AND SIDE EDGES, SAID PLATES HAVING THROUGHFLOW PASSAGES AND COACTING GASKETS FORMING AN INLET TO AND A SEPARATE OUTLET FROM EACH OF SAID CLOSED CHAMBERS AND ALSO FORMING AN OUTLET LEADING FROM EACH OF SAID OPEN CHAMBERS BETWEEN THE OPEN UPPER EDGE AND THE CLOSED BOTTOM EDGE THEREOF, AND MEANS FORMING A HOUSING ENCLOSING SAID PLATES AND INTO WHICH SAID OPEN CHAMBERS OPEN ALONG SAID UPPER EDGES THEREOF.