U.S. patent application number 11/813541 was filed with the patent office on 2008-08-21 for gasket assembly for plate heat exchanger.
This patent application is currently assigned to Alfa Laval Corporate AB. Invention is credited to Magnus Svensson.
Application Number | 20080196873 11/813541 |
Document ID | / |
Family ID | 36740797 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080196873 |
Kind Code |
A1 |
Svensson; Magnus |
August 21, 2008 |
Gasket Assembly for Plate Heat Exchanger
Abstract
A gasket assembly of a plate heat exchanger, comprising at least
one gasket (3) and a package of heat exchanger plates (2) which are
provided with inlet and outlet ports (4, 5, 6, 7) which constitute
channels through the package and between the heat exchanger plates,
whereby the heat exchanger plates are permanently joined in pairs
to constitute cassettes (1), the gasket is disposed between the
cassettes in a groove (12) in the heat exchanger plates and
delimits in combination with the cassettes in every second space
between plates a first flow passage for a first fluid, and the
cassettes delimit a second flow passage for a second fluid. The
gasket in the area around the ports comprises along its side facing
the porthole a circumferential protruding bead (14). The invention
also relates to a plate heat exchanger comprising the gasket unit,
a heat exchanger plate and a gasket according to the invention.
Inventors: |
Svensson; Magnus; (Lund,
SE) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Assignee: |
Alfa Laval Corporate AB
Lund
SE
|
Family ID: |
36740797 |
Appl. No.: |
11/813541 |
Filed: |
January 13, 2006 |
PCT Filed: |
January 13, 2006 |
PCT NO: |
PCT/SE2006/000049 |
371 Date: |
April 11, 2008 |
Current U.S.
Class: |
165/167 |
Current CPC
Class: |
F28F 3/10 20130101; F28D
9/005 20130101; F28F 2225/04 20130101; F28F 3/083 20130101; F28D
2021/0098 20130101; F28F 3/046 20130101 |
Class at
Publication: |
165/167 |
International
Class: |
F28F 3/10 20060101
F28F003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2005 |
SE |
0500216-7 |
Claims
1.-11. (canceled)
12. A gasket assembly of a plate heat exchanger, comprising at
least one gasket and a package of heat exchanger plates, the plates
being provided with through inlet and outlet ports which constitute
channels through the package and between the heat exchanger plates,
the heat exchanger plates being permanently joined in pairs to
constitute cassettes, the gasket being disposed between the
cassettes in a groove in the heat exchanger plates and delimiting
in combination with the cassettes in every second space between
plates a first flow passage for a first fluid, and the cassettes
delimiting a second flow passage for a second fluid, wherein the
gasket in the area around the ports comprises along its side facing
the porthole a circumferential protruding bead.
13. A gasket assembly according to claim 12, wherein the bead is so
configured that the gasket in the area around the ports comprises,
along its side facing the porthole, opposite recesses on upper and
lower sides of the gasket.
14. A gasket assembly according to claim 12, wherein each heat
exchanger plate has around the ports a circumferential ridge
provided on the outside of the cassette between the porthole and
the gasket groove.
15. A gasket assembly according to claim 14, wherein the bead of
the gasket abuts against the circumferential ridge around the
porthole.
16. A gasket assembly according to claim 12, wherein the bead is so
configured that the cassettes in combination with the gasket at the
ports provide a substantially smooth channel through the plate
package.
17. A gasket assembly according to claim 12, wherein the heat
exchanger plates are permanently joined in pairs by welding.
18. A gasket assembly according to claim 12, wherein the heat
exchanger plates are permanently joined in pairs by brazing.
19. A plate heat exchanger comprising at least one gasket and a
package of heat exchanger plates, the plates being provided with
inlet and outlet ports which constitute channels through the
package and between the heat exchanger plates, the heat exchanger
plates being permanently joined in pairs to constitute cassettes,
the gasket being disposed between the cassettes in a groove in the
heat exchanger plates and delimiting in combination with the
cassettes in every second space between plates a first flow passage
for a first fluid, and the cassettes delimiting a second flow
passage for a second fluid, wherein the plate heat exchanger
comprises at least one gasket assembly according to claim 12.
20. A heat exchanger plate which forms part of a package of plates
for a plate heat exchanger, the plate being provided with inlet and
outlet ports which constitute channels through the package and
between the heat exchanger plates, the heat exchanger plates being
permanently joined in pairs to constitute cassettes, a gasket being
disposed between the cassettes in a groove in the heat exchanger
plates and delineating in combination with the cassettes in every
second space between plates a first flow passage for a first fluid,
and the cassettes delimiting a second flow passage for a second
fluid, wherein the heat exchanger plate has around the ports a
circumferential ridge disposed on the outside of the cassette
between the porthole and the gasket groove.
21. A gasket for a plate heat exchanger comprising a package of
heat exchanger plates which are provided with inlet and outlet
ports, the ports constituting channels through the package and
between the heat exchanger plates, and wherein the heat exchanger
plates are permanently joined in pairs to constitute cassettes, the
gasket is disposed between the cassettes in a groove in the heat
exchanger plates and delimits in combination with the cassettes in
every second space between plates a first flow passage for a first
fluid, and the cassettes delimit a second flow passage for a second
fluid, wherein the gasket in the area around the ports comprises
along its side facing the porthole a circumferential protruding
bead.
22. A gasket according to claim 21, wherein the bead is so
configured that the gasket in the area around the ports comprises,
along its side facing the porthole, opposite recesses on upper and
lower sides of the gasket.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a gasket assembly of a
plate heat exchanger, comprising at least one gasket and a package
of heat exchanger plates which are provided with inlet and outlet
ports which constitute channels through the package and between the
heat exchanger plates, whereby the heat exchanger plates are
permanently joined in pairs to constitute cassettes, the gasket is
disposed between the cassettes in a groove in the heat exchanger
plates and delimits in combination with the cassettes, in every
second space between plates, a first flow passage for a first
fluid, and the cassettes delimit a second flow passage for a second
fluid. The invention also relates to a plate heat exchanger
comprising the gasket assembly, a heat exchanger plate and a gasket
according to the invention.
BACKGROUND TO THE INVENTION
[0002] Food manufacture is typically characterised by the need to
process and treat highly viscous products, e.g. concentrates for
carbonated beverages, juices, soups, dairy products and other
products of fluid consistency. For natural reasons, the hygiene
aspirations and expectations in this context are extremely high to
enable the requirements of various authorities to be met.
[0003] Plate heat exchangers are used in the food industry for a
number of different purposes. Problems with regard to so-called
dead zones, the accumulation of fibres and other solid material
which may be contained in products, and the possibility of flexible
and effective cleaning, are extremely important factors in this
context. The design of heat exchangers therefore plays a crucial
part in making it possible for effective heat transfer and hygiene
to be achieved while at the same time preventing so-called dead
zones in which products may be caught and hence become fertile
ground for bacteria growth.
[0004] In this context it is advantageous to use so-called
semiwelded plate heat exchangers, i.e. heat exchangers comprising a
number of cassettes formed by welding heat exchanger plates
together in pairs. The weld seam normally runs along the side edges
of the cassettes and around the portholes. A gasket is disposed
between the respective cassettes and is normally made of a rubber
material and situated in a groove of the heat exchanger plate. One
fluid flows inside the cassettes, and another fluid between the
cassettes. Semiwelded plate heat exchangers tolerate relatively
high pressures and make it possible to open the plate package and
clean the spaces between pairs of welded heat exchanger plates. The
welds which replace the gaskets in every second space between
plates round the heat exchange surface of the heat exchanger plates
reduce the need for gasket replacement and enhance safety.
[0005] The material and configuration of the heat exchanger plates,
the design of the heat transfer surfaces with regard to pattern and
press depth, etc., are important factors in hygienic applications.
A critical region of heat exchangers and particularly of heat
exchanger plates with regard to dead zones is at the portholes,
which are normally provided with a number of so-called nibs, i.e.
alternating ridges and valleys, evenly distributed about the
porthole in the form of a wave pattern. These nibs constitute
contact points and have the important function of absorbing forces
and supporting the structure against the high pressures which occur
in the heat exchanger. When two or more heat exchanger plates are
placed adjacent to one another, however, the nibs result in the
formation of spaces in the actual flow passage, i.e. dead zones in
which flowing liquid may become stationary and solid material
contained in the liquid may be trapped and accumulate.
[0006] The gaskets currently used with heat exchanger plates of
this type joined together to constitute cassettes take the form of,
for example, so-called "clip-on" gaskets, i.e. gaskets locked
firmly at the periphery of the heat exchanger plates and around the
portholes by protruding locking means disposed in the gasket which
are clamped firmly around the edge of the heat exchanger plate.
These protruding locking means may also make it more likely that
fibres etc. are caught, especially at the portholes.
[0007] GB 809 886 describes a plate heat exchanger for two
heat-exchanging fluids whereby the portholes are made circular and
plain in order to avoid the problem of fibres and particles being
caught. That solution is achieved by the edge of the porthole being
pressed outwards to form a flange or collar. The flanges of
opposite portholes are so disposed as to abut against one another,
thereby forming a smooth channel through the plate package. That
solution does however involve manufacturing difficulties.
SUMMARY OF THE INVENTION
[0008] The object of the invention is to eliminate or at least
reduce the problems indicated above and to provide an improved
solution for a porthole of a heat exchanger plate. What is in
particular aimed at is a new and better gasket assembly specially
intended for the portholes of a cassette comprising two heat
exchanger plates.
[0009] This object is achieved according to the invention by the
gasket assembly indicated in the introduction, which is
characterised in that said gasket in the area around the ports
comprises, along its side facing the porthole, a circumferential
protruding bead.
[0010] The configuration of the gasket assembly results in great
reduction of the so-called dead zones at the portholes. It provides
instead a plain surface in the passage through the port channel and
substantially avoids the risk of highly viscous liquids which may
possibly contain particles or fibrelike products being caught.
Should material nevertheless be caught, the plain surface of the
gasket in combination with the configuration of the porthole helps
to create conditions in which the material will be swept away. The
gasket assembly according to the invention thus also reduces the
risk of bacteria growth, which is a major and important advantage,
particularly in areas of application in which the hygiene
requirements are extra high.
[0011] According to an alternative embodiment of the invention, the
gasket assembly is so configured that the gasket in the area around
the ports comprises, along its side turned towards the porthole,
opposite recesses on the upper and lower sides of the gasket. Such
a design of the gasket makes it possible for the dead zones to be
largely eliminated altogether. This is a major advantage in such
areas as the food and drug industry, in which the hygiene
requirements are very strict.
[0012] According to a further embodiment of the invention, the heat
exchanger plate has about the port a circumferential ridge disposed
on the outside of the cassette between the porthole and the gasket
groove. According to an advantageous embodiment of the gasket
assembly according to the invention, the ridge and the gasket
cooperate in that the bead of the gasket abuts against the
circumferential ridge about the porthole, thereby ensuring that the
gasket is not dislodged from its position by the high pressures
which occur during operation.
[0013] According to an advantageous embodiment of the gasket
assembly according to the invention, the bead is so configured that
the cassettes in combination with the gasket at the ports provide a
substantially smooth channel through the plate package. In this
embodiment, the plain surface of the gasket in cooperation with the
configuration of the porthole helps to reduce the risk of material
being caught. According to further advantageous embodiments of the
gasket assembly according to the invention, the heat exchanger
plates are permanently joined together in pairs by welding or
brazing.
[0014] The object of the invention is also achieved by a plate heat
exchanger comprising at least one gasket assembly according to any
one of claims 1-7.
[0015] The object of the invention is also achieved with a heat
exchanger plate comprising the features indicated in claim 9.
[0016] The object of the invention is also achieved with a gasket
which comprises the features indicated in claim 10. An advantageous
embodiment of the gasket is indicated in dependent claim 11.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The invention is explained in more detail below by
describing various embodiments cited by way of examples with
reference to the attached drawings, in which
[0018] FIG. 1 depicts schematically a plan view of a gasket
assembly comprising a gasket and a heat exchanger plate according
to the invention,
[0019] FIG. 2 depicts schematically a plan view on a larger scale
of the gasket assembly according to the invention,
[0020] FIG. 3 depicts schematically a cross-sectional view of
various gaskets, whereby the gasket according to A represents a
known gasket and the gaskets according to B and C are two
alternative embodiments of the gasket according to the invention
which are disposed at the porthole of a plate heat exchanger
according to the invention, and
[0021] FIG. 4 depicts a perspective view of the porthole of a
gasket assembly according to the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0022] FIGS. 1 and 2 depict a cassette 1 comprising two heat
exchanger plates 2 permanently joined together and a gasket 3
according to the invention. The plates have at least four ports
constituting inlet and outlet ports 4, 5, 6, 7 and a heat transfer
surface 8 with ridges 9 and valleys 10. The cassette 1 may be made
by welding or brazing, whereby the two plates 2 are joined together
permanently along their periphery and around at least two of ports
4, 5.
[0023] Configuring the heat exchanger plates 2 in such a way that
as few contact points as possible occur between two mutually
adjacent cassettes prevents fibres and solid materials which may be
contained in the fluid being caught in the space between the
cassettes. According to the invention, the plates are also so
designed that contact points for necessary mechanical support occur
largely only on the inside, between two plates which are to be
joined together to form a cassette, by opposite ridges abutting
against one another. In contrast, at portholes 4 and 5 the plates
abut completely against one another and are joined together
permanently so as to form a seal against the fluid which is
intended to flow through the portholes. Portholes 6 and 7, which
constitute the inlet and outlet to the cassettes, are provided
instead with nibs 11 which are necessary for providing necessary
mechanical support at the porthole.
[0024] The gasket 3, which is preferably made of an elastic
material, e.g. rubber material, is disposed in a groove 12 which
extends along the periphery of the constituent plates of the
cassette and around ports 4 and 5. There is a ring gasket 13 round
ports 6 and 7. The purpose of the gasket 3 is to seal the space
between two cassettes, and it has in the area around ports 4 and 5,
along its side facing the porthole, a circumferential protruding
bead 14 which may have a cross-sectional configuration such as
represented, for example, by the gaskets according to B and C in
FIG. 3. The gasket may possibly comprise a metal or be surrounded
by a second material, e.g. metal, PTFE, etc.
[0025] To ensure that the gasket 3 is firmly disposed at the
porthole and is not pressed or does not slip out of the groove 12
at high pressures and temperatures, a circumferential ridge 15 is
formed in the plate about the port on the outside of the cassette
between porthole 4 or 5 and the gasket groove 12. The height of the
ridge 15 is such that there is a gap between two opposite ridges
when two cassettes are disposed adjacent to one another. In the
case of the gasket assembly according to the invention, the gasket
3 is thus situated in the groove 12 in such a way that the bead 14
abuts against the ridge 15 of the constituent plates of the
cassettes at portholes 4 and 5. This arrangement results in the
gasket being held securely in position while at the same time a
tight, plain and smooth surface is formed in porthole 4 or 5 and in
the port channel, as clearly indicated in FIG. 4.
[0026] FIG. 3 shows how the volume of the dead zone is affected by
the cross-sectional configuration of the gasket. When the gasket 3
has a configuration according to A, i.e. is provided with no bead
14, there is a large space bounded by the gasket A and the heat
exchanger plate at the porthole, which is normally surrounded by
nibs. This so-called dead zone traps fluid, whereby fibres and
other solid materials are caught and thus constitute fertile ground
for growth of bacteria.
[0027] In contrast, if the cross-sectional configuration of the
gasket is in accordance with the invention according to B, i.e. so
that the gasket in the area around the ports comprises along its
side facing the porthole a circumferential protruding bead 14, the
volume of the dead zone will be greatly reduced. The fact that the
bead 14 abuts against the ridge 15 also results in a smoother
surface in the port channel. In another embodiment of the
invention, the gasket has a cross-sectional configuration according
to C, whereby the bead 14 is so configured that the gasket 3 in the
area around the ports comprises, along its side facing the
porthole, opposite recesses 16 on the upper and lower sides of the
gasket. In this case the whole space at the portholes between two
cassettes is largely filled by the gasket, the dead zone is
eliminated and a plain smooth surface is formed in the port
channel.
[0028] A gasket assembly configured according to the invention
whereby a ridge around the porthole in a heat exchanger plate
cooperates with a bead of the gasket results in a port channel with
maximum possible smoothness of surface, with greatly reduced or no
dead zones. This is of great significance, particularly in plate
heat exchanger applications where there are strict hygiene
requirements, but also in other applications where obstruction and
so-called fouling are normally a problem. The gasket assembly and
the heat exchanger comprising the gasket assembly according to the
invention make it possible to achieve a plate heat exchanger which
meets high hygiene requirements and is easy to clean.
[0029] It should be noted that other embodiments not here cited of
the invention are also possible without departing from the scope of
the invention which is indicated in the attached claims.
* * * * *