Note: Descriptions are shown in the official language in which they were submitted.
` ~153362
The heat exchanger comprises a number of parallel,
spaced-apart, perforated plates, which are connected in a fluid-
tight manner along their outer periphery, and, with annular
plates, also along their inner periphery in order to form the
wall of a vessel for a first fluid passing through the perfora-
tions in the plates. Distribution and collecting chambers are
arranged in direct communication with the outermost plates in
` the stack. The stack may be enclosed in a shell, which defines
a passage for a second fluid. One or more stacks of annular
plates may be arranged concentrically around a core stack, and
the second fluid may be conducted through spaces between the
stacks. Alternatively one fluid may be conducted through the
core stack and the other fluid may be conducted through an outer
~;' stack. The plates are preferably dished, or bowl-shaped, having
a low collar along their outer periphery, and with the annular
plates also along their inner periphery. The plates may then be
; joined by welding along these collars.
1 This invention relates to a heat exchanger for exchang-
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~ ing heat between two fluids.
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When exchanging heat between two fluids apparatus of
different types may be used. One type of such exchangers in-
cludes a number of interconnected, perforated plates. One fluid
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passes through holes in the plates, while the other fluid passes
'~ through tubes upon which the plates are fitted. It is necessary
to enclose the plates outwardly by some sort of shell, to define
the flow path for the first fluid.
Such arrangements are expensive and not very favourable
with respect to the heat transfer properties.
The aim of the present invention is to propose a simpli-
fied design of heat exchangers including a plurality of parallel,
perforated plates, where a first fluid flows through the plates
~ substantially perpendicularly to the plans thereof.
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1~53362
Aceording to the present invention there is provided a
heat exchanger comprising a stack of parallel, perforated plates
adapted to permit flow of a first fluid substantially perpendie-
ularly to the plane of the plates, the plates being interconneeted
in a fluid tight manner along their outer periphery to form the
outer wallof a stack-like vesselfor the fluid passingthrough the
plates, anddistribution andcollection chambersfor saidfliud arran-
ged indirect communicationwith theoutermost platesin saidstack.
;1 Such a heat exchanger may be enelosed in a shell defin-
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ing a flow path for a second fluid.
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According to a development of the invention the plates
are annular, and are interconnected along their outer, as well
as along their inner periphery, and further means are then pro-
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- vided for directing the flow of a second fluid to the passage
~` formed within the stack of plates.
A heat exehanger composed of annular plates may eonsist
of two or more eoneentrieally arranged staeks of plates.
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115336Z
The radial extension of an outer plate i9 prefera.bly about one
ha.lf of the corresponding mea~sure at an inward plate, When the
heat exchanger includes at least three concentrlc pl~ltes~ the
plates in the outermost sta.ck are manufactured from thicker material
than the plates of the inwa.rd stacks, in order to take the increased,
total pressure ca.used by the enlarged area., due to the increased
diameter~ into account.
A heat exchanger according to the invention may be designed in
such a manner, that steam is supplied to passages inward of the
plates, while the fluid to be heated flows through the plates. As
an alternative, or for augmenting the steam heating, electric
heating elements may be fitted in said passages. When exchanging
heat between two fluids having about equal coefficients of heat
transfer a sta.ck of annular plates may be fitted outside a core
sta.ck of plates, the heating a.rea.s of the two types of plates
being about equal.
The inner diameter of an outward plate is selected so it only :.
slightly exceeds the outer diameter of an inner pla.te and the two
stacks are permanently bonded together by casting a heat conduct-
ing materia.l, for instance molten brazing solder, into the clea-
rance between the stacks.
A heat exchanger comprising a stack of annular plates may include
a shell enclosing the stack of plates with a clea.rance and collect-
ing and distribution headers communicating said clearance with the
central passage for parallel or series flow of the second fluid.
The plates are preferably dished (bowl-shaped) having a. low collar
along their outer periphery, and with annular plates also a low
colla.r along their inner periphery, the plates being interconnected
by welding along said colla.rs.
Alternatively the plates ma.y be formed as flat rounds, which are
fitted between two concentric tubes and by thermical and/or
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:1~5;~36Z
mechanical working are fluid-tightly joined thereto, to -form the
vessel for the passa.ge of the first fluid.
In order to provide a counter-flow path for the fluid through th~
stack the perforations in the individual pla.tes a.re arranged in
two series, ra.dially sepa.rated from each other, and annular spacers
are then fitted between adjacent plates in the radia.l space between
the two series of perforations.
Brief descriPtion of the drawings
Figure 1 shows an end view of a plate,
Figure 2 shows, partly in section, a heat exchanger composed
of pla.tes according to Figure 1,
~igure 3 shows a modified embodiment of a hea.t exchanger according
to the invention, composed of annular plates and suit-
. able as a. steam hea.ted oil pre-heater,
~igure 4 shows a heat exchanger according to the invention, and
including two concentrically arranged annular plates,
Figure 5 shows a modification of the embodiment according to
~igure 4,
; Figure 6 shows a portion of an end view of a heat exchanger
including three concentric, annular plates,
i~ Figure 7 shows a vertical section through part of the heat exchanger
according to ~igure 4, and
, Figures 8 and 9 show two modified embodiments, where a stack of
plates is enclosed in a shell, defining the flow path
for a second fluid.
Description of some preferred embodiments
The plate 1 shown in Figure 1 is circular, and provided with a
: number of radia.lly directed slots 2 arranged in a symmetrical
pa.ttern. The pla.te is along its outer periphery provided with a low
collar 3, and the pla.te will in this manner, a.s viewed in a cross
section, show a bowl-sha.ped form. The sha.pe and position of the
slots is not deciding. Any type of pa.ssage providing openings mav
be used and they are here referred to as "perforations".
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1~5336Z
When manufa.cturing a core portion of a heat exchanger the plates
are fitted on top of each other~ and are interconnected a.long the
peripheral coll~rs 3. The connection is prererably ma.de by weldlng,
for instance butt welding or TIG welding, even if bra.zing may be
accepta.ble in certain installa.tions.
When fitting the pla.tes together a following pla.te is rotated
somewhat in relation to a preceeding one, so the slats 2 in adja-
cent plates will not be loca.ted directly opposite to each other,
but so the fluid having to pass through the plates will be forced
to follow a.tortuous path.
Domed end plates 4 and 5, respectively, are atta.ched to the outer-
most plates of the stack. In such manner a passage 6a-6b for a
first fluid is obtainable, sa.id fluid passing axially through the
stack of pla.tes.
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The sta.ck is enclosed in a shell 7. Within the latter a wire 8,
wound helically around the stack will form an extended flow path
for a second fluid entering at 9a and leaving the shell at 9b.
It is evident that there is a flow of heat through the plates,
towards, or away from the outward wa.ll formed by colla`rs 3 and
the welding seams there, respectively, depending upon if it is
interesting to cool, or to hea.t the first fluid. The heat transfer
; will be better than in embodiments, where the other fluid flows
through tubes pa.ssing through the plates.
The hea.t exchanger shown in Figure 3 is in the first hand intended
as an oil pre-heater using steam as heating fluid. The heat ex-
change will here occur between two fluids having noticeably
different coefficients of heat transfer, which means that the
surfaces contacted by the two fluids may differ considerably in size.
The main portion of the heat exchanger consists of a number of pla~es
10, the centre portion of which is formed as an opening 11. The
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plates, the sllape of which is evident from ~ig~re 4, are provlded
with a number of ra.dially directed slots 12 arranged with an even
pitch. The slots 12 extend substantia.lly all the way from the
central opening 11 to the outer perihpery of the plate.
According to the invention the plates are provided with a low collar
13 along its outer periphery, and are, as described above, fluid-
tightly interconnected. There is also a corresponding low collar
15 around the central opening, and the plates are welded together
along these inner collars also,.so a central passage 14 is formed.
The two collars will also here provide a bowl-shaped form at plates
10, which makes possible the flow of a first fluid within the stack
of plates being defined by collars 13 and 15 and the pertaining
weld seams, and for a second fluid through the central passa.ge,
without it being necessa.ry to use any external shell for guiding
the first flow.
The stack of annular pla.tes is made into a heat exchanger by closing
the central passage 14 upwardly by a domed lid 16, and closing
the passage downwardly by a bowl-shaped member 17. A steam supply
pipe 18 extends through this member and reaches centrally through ~¦
passage 14, about to the level of the uppermost plate in the stack. .;
A condensing water return conduit 19 is attached to the bottom of ~`
the bowl-shaped member 17. Means for governing the supply of steam
in relation to occasional need, as well as for removing the
condensating water, belong to known technique and need therefore
not be described here.
A domed end plate 20 is welded to the upper end of the stack of
plates, and a further end plate 21 is welded to the bottom of the
stack, as well as to the bowl-shaped member 17. A supply conduit
Z2 for the oil is attached to the lower end plate 21, and an outlet
conduit 23 for the heated oil is attached to the upper end plate 20.
The heat exchanger is preferably encased in a heat insulting cover,
not shown, and it is evident that the heat excha~ger, with small
115336Z
modifications concerning the fluid supplied to the central passage,
may be u-~ed for cooling oil, or for heat exchange in general, where
the coefficients of heat transfer for the two fluids are markedly
different.
Figure 4 show~ (in an other scale) a cro99 section through a heat
exchanger having a higher capacity than that according to Figure 3.
The heat exchanger comprises a ~tack of plate~ 10 of the same type
as shown in Figure 3, but furthermore a second stack of plates 30
arranged concentrically around the first ~tack. The plates in this
second stack is provided with radially arranged slots 32.
This figure shows a preferred location of slots 12 and 32, and ~s
mentioned early, each plate is rotated on this occasion one half
of the slot pitch in relation to a preceeding plate, while the
plates are welded together, so the fluid will move in a zigzag
path. It should also be noted, that slots 32 in the outer plate
are selected so they will be located between two slots 12 in the
central plate. Hereby the best conditions for the distribution of
the heat supplied are obtainable.
Plates 30 are also provided with rim collars corresponding to
13 and 15 at the inward plates, and they are welded together in the
same manner, so a fluid path is obtained through this stack.
The inner diameter of plates 30 is bigger than the outer diameter
of plates 10, whereby a passage 34 will be formed between the two
stacks of plates. Passages 14 and 34, as well as the fluid paths
through the stacks, respectively, are interconnected, for instance
in the manner tobe described in connection with Figures 6 and 7.
In the embodiment shown here a heat transfer occurs from (or to)
a fluid passing the central passage 14 and the annular passage 34.
Plates 10 in the core stack will thus be heated from two sides,
while plates 30 in the outer stack will be heated from passage 34
only. The radial extension of plates 30 is therefore about one
half of the radial measure of the inner plates 10.
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Figure 4 further indicates a modification for augmenting the steam
heating shown in the embodiment according to Figure 3, by ~ttting
electric heating elements 3S in the central passage 14, as well
as in the annular passage 34.
On many occasions it may be desirable to heat fuel oil for the
burners of a boiler, when this iq to be qtarted up, i.e. before
steam is available for heating purpose~. It will then be possible,
temporarily to obtain the pre-heating with the electric elements,
but it is evident that the heat exchanger can easily be dasigned
so the electric elements will be the main, or sole heating source.
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On occasions it may be desirable to arrange an exchange of heat
between two fluids having about the same coefficient of heat
transfer, for instance exchange water/water. A design according
for instance to Figures 3 or 4 will then provide too small a contact
surface for one of the fluids. It may then, as shown in Figure 5,
be advantageous to arrange two or more concentric stacks of plates
and to direct the two fluids so they flow through different stacks.
A core stack may then be selected to include plates of type 1 or
type 10, and distribution and collecting headers are then arranged
at the ends of this stack. Plates 30a of the outer stack are here
formed so their inner diameter is slightly bigger, only, than the
outer diameter of plates 1. When the two stacks are fitted to-
gether the outer stack is fitted outside the core stack and the
narrow passage 34a between the two stacks is filled with molten
brazing solder, or some other heat conducting compound, so a good
heat transfer between the two stacks is obtained. Suitable distri-
bution and collecting headers are then attached to the ends of the
outer stack of plates. It is evident that this will provide a far
better contact surface for the other fluid, than what is obtainable
with the embodiments according to Figures 3 or 4. The outer diameter
of plates 30a will have to be selected so a desired relationship
between the heat exchanging surfacesin plates 1 or 30a is obtained.
Figures 6 and 7 show details of a high-capacity heat exchanger
comprising three concentric stacks of pl-tes.
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The core stack is composed of plates 10 in the same manner as in
the embodiments according to Figures 3 and 4. Outside the core
there is a second stack of plates 30b~ of basically the same type
as plates 20 in ~igure 4, but having a bigger radial extension
than those~ as this stack will be heated from lts outside also.
Outermost there is a stack of plates 40. As these plates wlll be
heated from their inward side onlY,their radial extension is less
than that of the inward plate~. Plates 40 are manufactured from a
thicker material than the other plates and will thus provide an
increase in the heater structure, which is important as the heater
will have a considerable extension in the radial direction.
Slots 12, 32, 42 are provided in the plates to form flow paths for
one of the fluids. The other fluid will pass through central
passage 14 and the annular passages 34 and 44.
For the first fluid, passing plates 10, 30b and 40, a collecting
chamber 41 is formed at the ends of the stacks, this chamber being
outwardly defined by a cylindrical wall 43 forming an extension of
the outward wall of the outermost stack, and being covered b~r a
lid 43a. An outlet for the first fluid, corresponding to the outlet
23 of Figure 1, is provided in this lid.
The arrangement at the lower ends of the stacks will he of basicall~-
the same nature, as i~ shown in Figure 6 including a conduit for
removing condensing-water.
The second fluid is supposed to enter from below into the central
passage 14, which here is upwardly terminated by a high dome 16a.
From the latter a number, here four, branch pipes 45 extend radially
for distributing the second fluid to the annular passages 34 and 44.
On top of each of those passages there is an annular chamber 41
and 47, respectively, each defined by annular plates 48 and 49 and
covered by lids 50, 51. The branch pipes 45 from dome 16a pass
through annular chamber 46 to annular chamber 47. Also with this
fluid the arrangement at the lower ends of the passages will be
basically the same as just described.
`"` llS336Z
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,; Figure 8 shows a hea.t exchanger comprising a stack of plates 10,
of basica.lly the same shape a,s those shown in Figure 3, i.e. they
are provided with a central opening 11~ slots 12~ and outer and
~: lnner collors 13 and 15~ respectively~ welded together to form a.
vessel for a first fluid,
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~i The stack is here enclosed in a. shell 60, which surrounds the stack
with a clearance 61. The shell i9 termina.ted by upper and lower
." end plates 62 and 63, respectively.
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The stack of plates 10 is welded to the shell 60 a.d'jacent to the
~,' lower end plate 63, so a collecting chamber for the second fluid
is obtained. This fluid is introduced by way of a conduit 64, which
~` : passes through the lower end plate 63, to the centra.l passage 14,
~j~ and is, by way of branch conduits 65 at its lower end distributed
.~ to clearance 61. The second fluid will thus flow in parallel flows
~ past the stack, interna.lly, as well as externally thereof.
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:~ The two flows are collected in an upper chamber 66, below the upper
, end plate 62~ and is led away through a conduit 67.
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`'~ The first fluid is admitted by way of a conduit 68, which passes
,'. through the upper end plate 62. An arrangement includ1ng branch
pipes 69, substantially the same as is shown in ~igure 7, distri-
butes the first fluid to the stack of plates. The first fluid is
. collected i~ a,chamber 70 between the lower end plate 63 and the
, welding seam 71 connecting the lower end of the stack to shell 61.
~, Thè effluent passes away through a conduit 72.
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,'~ , The inlet conduit 68 for the first fluid is not attached to end
", plate 62, but pa,sses through the latter with a sliding fit. A
," packing box 73 is fitted to end plate 62, sealing against the out-
~ side of conduit 68, and permitting therma.l movements between the
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i,~. core sta.ck and the enclosing shell.
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:` With the embodiment according to Figure 9 fla.t plates 80 are u~sed.
The plates a.re provided with perforations 81 and 82 arranged in
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two radially spaced series.. In this manner each plate will show a
pa.ttern substantially like what is obtained by the two thermally
: bonded pla.tes 1 and 30a. in Figure 5. Here, however, the plates
are annular to form a central passage. Instead of tho moltcn solder
used in Figure 5 rings 83 are fitted between the plates to form a
counter-flow path for the first fluid through the stack.
The lay-out of the stack varies somewhat from what is shown in the
preceeding figures, insofar a.s the pla.tes a.re not directly welded
together, but a.re fitted between an inner tube 84 and an outer tube
85, to which they a.re fluid-tightly joined.
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This joining may be brought about by crimping the tubes to the plates,
and/or by rolling or other mechanical working for forcing the tubes
against the edges of the plates Rings 83 will, during this opera.-
tion ensure tha.t the plates are maintained at a. proper mutual
spacing.
The stack thus formed is enclosed in a. shell 86. The outer stack
tube 85 is continued by a tubular member 87, which is provided
with a supporting flange 88, and, underneath the latter, with an
inlet conduit 89 for the first fluid.
A tubula.r partition wall 90 within the tubular extension member 87
is connected to the lower end of the stack in the space between
the two series of perfora.tions 81 and 82, and directs the first
fluid upwardly through the outer series of perfora.tions 81. An
annular cover 91 is fitted to the upper end of the stack and directs
the flow of the first fluid towards the inner series of perforations
. 82.
When the first fluid, in counter-flow has passed through the stac~
it is collected in a chamber 92, between an extension 93 of the
inner tube 84 and the partition wall 90, and is conducted away by
a connection 94.
Shell 86 is provided with an end flange 95, which sealingly engages
~5~362
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supporting flange 88. The second fluid i9 introduced through the
centra.l tube 93 + 84 to an upper chamber 96, below a domed end
plate 97, which closes-off shell 86 upwardly. Here the fluid i9 I'
distributed to the clearance 98, which i9 provided between the
sta.ck and the shell, and the fluid is fina.lly conducted awa.y through
a connection 99. ¦~
The sta.ck and the shell are connected by the two flanges 88 and 99
only, and have thus satisfa.ctory possibilities for thermal movements.
~y disengaging the two flanges it is possible to remove the shell
~: for cleaning and supervision.
The expressions "upper" and "lower" used above refer to the
positions shown in the drawings, and must not be interpreted as
meaning any limitation a.s to the practical mounting of the heat
exchangers. The arrangement of counter-flow within a sta.ck ma.y of
course be obta.ined by a. suita.ble positioning of the perforations
. in plates of type 10, i.e. with externa.l and interna.l collars
13 and 15~ if distance rings corresponding to rings 83 of Figure 9
a.re provided.
The embodiments shown and described a.re examples only, and it is
evident that many modifications may be performed within the scope
of the appended cla.ims, such modifications being determined by
the desired capacity, if the intention is to heat or to cool the
, primary fluid, and to a large extent also by the nature of the
i fluids, in the first hand their coefficients of heat transfer.
The pla.tes a.re manufactured from ma.terial having fine heat conduct-
I ing properties~ and may be formed in many ways as alternatives to
i the forms shown. The pla.tes are preferably dished, but it is
possible to start with plane plates, and to fit distance elements
in the form of thin rings, corresponding to those in Figure 9, and
having the same outer diameter as the plates. The plates and the
rings will then be welded together. Alternatively the plane plates
may be mounted in spaced rela.tionship in a. fixture, whereafter the
marginal spacines are bridged by welding ~aterial.
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Beside with heaters or coolers, respectively, heat exchangers of
a.bove mentioned type may be used as components in boilers, forming
convection or economiser parts thereof. The combustion gase~
will pass through the plates~ while the water flows externally Or
the sta.ck, or stacks, and possibly through a central pa.ssage therein.
- A rapid and efficient heat transfer from the gases to the water is
brought about, and whenstarting up the boiler the natural water
circulation will commence immediately.
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