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EP 0 117 821 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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11.11.1987 Bulletin 1987/46 |
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Date of filing: 24.02.1984 |
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International Patent Classification (IPC)4: F28F 9/14 |
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Compression sealing of tubes within shell and tube heat exchangers
Druckfixierung von Röhren in Röhren-im-Mantel-Wärmetauschern
Fixation de tubes par compression dans des échangeurs de chaleur du type "tubes et
enveloppes"
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Designated Contracting States: |
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AT BE CH DE FR GB IT LI LU NL SE |
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Priority: |
28.02.1983 US 470806
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Date of publication of application: |
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05.09.1984 Bulletin 1984/36 |
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Applicant: BALTIMORE AIRCOIL COMPANY, INC. |
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Jessup, Maryland 21227 (US) |
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Inventors: |
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- Flamm, Katherine K.
Baltimore
Maryland 21228 (US)
- Morrison, Frank T.
Arnold
Maryland 21012 (US)
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(74) |
Representative: Ahner, Francis et al |
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CABINET REGIMBEAU
26, avenue Kléber 75116 Paris 75116 Paris (FR) |
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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Background of the invention
[0001] There have been a number of devices and sealing means used to seal the tubes and
the shells in tube and shell heat exchangers so that fluid flowing in either medium
would not intermingle.
[0002] Typically, brazing, welding or roller-expansion has been used to seal the tube to
tube sheet joints and tube sheet to shell joints in a typical shell and tube heat
exchanger. The disadvantages of these sealing methods are : 1) that the individual
tubes cannot be easily removed, 2) the shell side cannot be cleaned mechanically,
and 3) any use of plastic baffles in the shell would melt during brazing, or welding.
[0003] Other methods have been used to compression seal the tubes to the tube sheet, joints
and the tube sheets to the shell joints in a typical shell and tube heat exchanger.
There were several disadvantages to previous methods of compression sealing. One method
required the compressing tube sheet to be welded to the shell. This prevented access
to the internal shell area for cleaning or replacement of tube support baffles and
allowed tubes to be replaced only singly and by very complicated procedures. Several
methods required the presence of internal welded lugs or tube sheet end stops which
complicated the removal of tube support assemblies and prevented the use of conventional
tube support baffles. Another method required the presence of removable pressure-transfer
devices in place of welded lugs and these components obstructed flow in and out of
shell and tube nozzles causing wasted energy due to excessive pressure losses. Further
methods required the use of four tube sealing gaskets and eight tube sheets per heat
exchanger assembly, which caused several problems : (a) more costly assemblies due
to the larger number of components, (b) the multiple components occupied space which
reduced the effective tube length available for heat transfer. A final method required
the use of very close tolerance components to effectively seal the cut- ends of the
shell component.
[0004] More specifically, the present invention relates to a shell and tube heat exchanger
comprising an extension shell and inner shell, a plurality of tubes and a sealing
means, so that fluid flowing within the tubes and within the shell cannot mix, which
comprises flanged gasket sealing means to seal the shell from outside atmosphere,
said flanged gasket sealing means being compressed between two shell flanges and two
tube sheets by means of bolts inserted through the flanges, and a tube sealing means
to seal the tubes from the inner shell of said heat exchanger, said tube sealing means
being compressed between said tube sheets, according to the preamble of claim 1.
[0005] A shell and tube heat exchanger of this type is disclosed in US-A-2 762 611, as illustrated
at figure 6 thereof. In particular, the tube sealing means used as part of this exchanger
are a plurality of deformable packing ring elements mounted onto each one of said
tubes, these ring elements bearing against an associated annular shoulder. Another
embodiment is illustrated at figure 7 of this patent, comprising specific sealing
means 85 and 99 :
1) a flanged gasket 99 to seal the shell from outside atmosphere, said flanged gasket
being compressed between a shell flange and one of two tube sheets by means of bolts,
2) a series of deformable annuli 85, one for each tube, to seal the tubes from the
inner shell, said annuli being compressed between the two tube sheets.
[0006] Such sealing means involve a lot of components, and furthermore make difficult to
obtain regular compression forces on each of the tubes, mainly due to tolerances of
both the deformable annuli and the tapered edge of corresponding aperture of adjacent
tube sheets.
[0007] The invention intends to solve this technical problem by providing sealing means
which involve a small number of components, and ensure that proper compression forces
are exerted on the internal tubes.
[0008] A similar state of the art is illustrated by two other documents hereafter commented
:
1) DE-A-1 064 966 discloses the use of a full-face gasket compressed between two tube
sheets, without flanged gasket sealing means; when tightening the bolts disposed around
the shell flanges, the full-face gasket is outwardly radially expanded (as shows the
curved outer section illustrated at figure 2) : as a consequence, compression forces
on the internal tubes cannot be properly exerted due to this expansion, and more specially
for the tubes which are near to the bolting zone.
2) GB-A-1 604 180 discloses the use of a retaining sleeve 16 which prevents outward
yielding of the elastic material when pressure is applied by the tube sheets 11, 14.
This sleeve 16 :
is not adjustable in peripheral length,
surrounds the external end surface of the jacket tube and of the extension tube, so
that said end tubes have to slide between the sleeve and corresponding tube sheet.
[0009] Thus, it is an object of this invention to provide a shell and tube heat exchanger
as defined in the preamble of claim 1, having no mechanical components specifically
mechanical stops or pressure-transfer devices, internal to the shell, and wherein
proper compression forces are still exerted on the internal tubes, without involving
a lot of components.
[0010] This is achieved by providing a shell and tube exchanger of the above type, wherein
the tube sealing means is a full-face gasket and is contained around its periphery
by a retaining structure to prevent outward radial expansion of said full-face gasket,
said retaining structure including a peripheral ring which is mechanically adjustable
in peripheral length and diameter and abuts on the peripheral edge of the two tube
sheets, so that proper compression forces are exerted on the plurality of tubes by
the expanding full-face gasket, according to the characterizing portion of claim 1.
[0011] Other advantageous features can be further provided, as defined in the dependent
claims.
[0012] To better understand the invention there are shown provided three Figures. Figure
1 is an isometric cut-away view of the sealing means on a typical shell and tube heat
exchanger.
[0013] Figure 2 shows a cross-sectional view of the sealing means, which also incorporates
a clamp ring gasket retaining assembly.
[0014] Figure 3 shows an isometric view of the clamp ring gasket retaining assembly of the
sealing means.
[0015] Referring now to Figure 1, there is shown a typical shell and tube heat exchanger
1 consisting of a shell 2 and a plurality of tubes 3 located within the shell, preferably
in a symmetrical or evenly-spaced pattern within the shell 2. Any fluid flowing with
the tubes 3 enters the tubes or leaves the tubes through a conduit tube side connection
31. Fluid flowing counter to the fluid within the tubes and outside the tubes but
within the shell 2 enters or leaves the shell and tube heat exchanger 1 through the
annulus conduit connection 30. Only one side or one end of the typical shell and tube
heat exchanger is shown in Figure 1, but our sealing means would similarly apply to
the other end of the shell and tube heat exchanger which is not shown.
[0016] There is provided a flange portion 4 on the end of the shell 2. This flange portion
is usually welded onto the end of the shell and is an annulus type flange having a
typical overlap. Adjacent the flange 4 is a flange gasket 5. The flange gasket merely
fits around the face of flange 4 and has an annular clear central portion so that
the tubes 3 can pass therethrough.
[0017] Adjacent the flange gasket 5 is a tube sheet 6. The tube sheet is made of any metal
typically steel, brass, or stainless steel or can be made of other non-compressible
materials such as plastics or reinforced plastics. The tube sheet 6 is of a preferably
circular design and has individual holes 50 therethrough corresponding to and in alignment
with the individual tubes 3, which holes are of a slightly larger diameter than the
outer diameter of the tubes 3 so that the tube-ends can pass through the holes, and
the tube sheets can exert a maximum clamping force to compress the gasket to a maximum
to prevent tube seal leaks.
[0018] Adjacent the metal tube sheet 6 is a full-face gasket 7. This gasket is circular
and is solid- faced except for individual holes 51 and 15 therein, which holes again
line up with the tubes 3 and bolt holes for flanges 4 and tube sheets 8. The diameter
of these holes 51 is slightly smaller than the outside diameter of the tubes in order
to maximize the gasket clamping force when compressing the full-face gasket 7 over
the smooth ends of the tubes 3.
[0019] Next to the gasket 7 is another metal tube sheet 8 with holes 52 and 15 therein,
similar to those described for the metal tube sheet 6.
[0020] Located inside shell 2 is the primary tube bundle assembly composed of tubes 53,
segmental support baffles 54 and baffle spacer rods 55. It can be readily seen that
this entire assembly of 53, 54, and 55 components can be removed from shell 2 after
the flanges, gaskets, tube sheets, and outer shell 32 are removed, since there are
no lugs internal to shell 2 to prevent removal.
[0021] Adjacent the metal tube sheet 8 rests flange gasket 9 which fits against the annular
circular flange 10. Flange gasket 9 is similar to flange gasket 5 previously described.
The entire series of flange gaskets and metal tube sheets are then adjacent to flange
10 which is located at the end of extension shell 32.
[0022] Extension shell 32 is an extension or continuation of shell 2 and is fitted with
a tube side connection 31 through which fluid flowing within the tubes enters or leaves.
Extension shell 32 is also preferably fitted with flange 33 on its other closure end
(when contrasted with flange 10) so that the extension shell 32 of the shell 2 can
be sealed off from the outside atmosphere. This is accomplished by having end closure
flange 33 part of the extension shell 32 and having adjacent flange 33, an annular
flange gasket 34 similar to gaskets 5 and 9 and finally having an end plate or end
closure 35 sealing the end of the extension shell 32 of the shell and tube heat exchanger
1.
[0023] As can be seen in Figure 1 when one draws flange 10 and flange 4 closer together
to thus compress the two flange gaskets 3 and 9 and the center or full-faced gasket
7, the compression will cause gasket 7 to expand radially inward and thus seal each
tube from the fluid within the shell 2 but outside the tubes 3. The metal tube sheets
8 and 6 in conjunction with flanges 10 and 4 compress the rubberlike flange gaskets
9, 5 and 7 to form a seal between both the tube and tube sheets, and the inner and
outer shells to atmosphere.
[0024] The flange gaskets 9 and 5 and the main center gasket 7 in addition to flange gasket
34 can be made of any sealable and flexible material particularly rubber or any type
of elastomeric material which would not tend to corrode or decompose in the presence
of the fluid used in the shell and tube heat exchangers.
[0025] The tube sheets 6, 8 and blind or end flange 35 are made of non-compressible material
and preferably of metal such as steel, brass or stainless steel. The entire sealing
means is compressed by any means but particularly by the use of bolts 40 which fit
through holes 11 in the flange 4 and correspondingly fit through singly aligned holes
12 in flange gasket 5, holes 13 in the tube sheet 6, holes 14 in the center gasket
7, holes 15 in the tube sheet 8, holes 16 in the flange gasket 9 and finally holes
17 in the flange 10. Once the bolt extends through the holes 17 in flange 10, nuts
41 can be screwed onto the threaded portion 42 of bolts 40 and the entire ensemble
tightened to thus force the flanges and tube sheets to compress the flange gaskets
5 and 9 and main center gasket 7 and thus effectively seal the shell and tube heat
exchanger.
[0026] Similarly, the end of the extension shell 32 can be sealed from the atmosphere by
means of compressing the end closure 35 to flange 33 to thus compress the flange gasket
34.
[0027] This will permit the mechanical cleaning of the interior of tubes without removing
or disturbing the tube compression seals or any external piping connections. Typically
bolts 43 can be inserted through holes 38 in flange 33 and correspondingly slipped
through aligned holes 37 in flange gasket 34 and extend through holes 36 in end closure
35. Also, the bolts can go in reverse order. Typically one would screw nut 44 on the
threaded portion of bolt 43 and tighten the entire outer sealing means. The holes
through which the bolts pass can be equally spaced around the entire annulus of the
flanges which extend above the outer diameter of the shell 2 or shell extension 32.
Typically there would be about 20 holes of about 1/2 inch (12,7 mm) diameter on a
flange being on an 8 inch (203 mm) diameter shell.
[0028] Also there is shown in Figures 2 and 3 a clamping structure to prevent outward expansion
of gaskets. Thus, this illustrates the relationship between inner shell 2, extension
shell 32, flange bolts 40, ring gaskets 5 and 9, metal tube sheets 6 and 8, gasket
7 and tubes 3. Also there is shown a preferred variation of outer clamp ring 45 with
clamp ring flange 46 and clamp ring bolt 47. Thus, Figures 2 and 3 illustrate an arrangement
or functional relationship that exists for the outer clamp ring which provides an
entrapment to prevent outward radial expansion of gaskets when assembly clamp bolts
40 are tightened. This assures that proper compression forces are exerted on the internal
tubes 3 by the expanding full gasket 7 to allow use of the described invention for
application to higher internal pressure duties. Indeed, this component can be employed
to increase the range of application to higher internal design pressures than that
possible with some older designs wherein standard non-clamp ringed versions were limited
to lower pressure duty. By tightening bolt 47, the clamp ring flanges 46 move closer
together, making the ring tighten to a smaller diameter which then braces the outer
edges of the gasket(s) 5, 7 and 9 to prevent their outward expansion when subsequently
tightening bolts 40 to perform the heretofore described sealing of tubes and shell.
[0029] While the circular flange 45 tube sheets 6 and 8 and gaskets 5, 7 and 9 arrangement
described is preferred, an alternate logically-arranged assembly of gaskets, flanges
and tube sheets is visualized which are identical in arrangement of assembled components,
but having an outer periphery of square, hexagonal or other non-circular configuration,
while retaining preferably circular- shaped internal holes, shell and extension shell
configuration. Also, somewhat non-circular tubes and gasket holes can be utilized
effectively with this design concept. In this optional configuration, one might envision
and accomplish certain advantages of reduced manufactureing cost or reduced material
scrap ratios when fabricating multiples of components such as flanges, gaskets or
tube sheets by conventional high speed manufacturing methods.
[0030] While the outer shell end closure 35, gasket 34 and bolts 43 of Figure 1 represent
the preferred mechanical arrangement to allow the most ideal accessibility for maintenance
and repair or reassembly of all internal components, an alternate variation, potentially
lower cost and/or more leak- free concept employing a welded end cap to completely
close the outer end of the extension shell 32 may be employed to perform the required
closure of the outer end of the extension shell 32, eliminating the need for flange
33, gasket 34, bolts 43, nuts 44 and utilizing an end-plate or end closure without
holes, merely welded all around the periphery thereof to the shell 32. However, this
will preclude the ability to clean the interior of tubes, unless inlet and piping
connections are dismantled and compression seal bolts removed.
1. A shell and tube heat exchanger comprising an extension shell (32) and inner shell
(2), a plurality of tubes (3) and a sealing means, so that fluid flowing within the
tubes and within the shell cannot mix, which comprises flanged gasket sealing means
(5, 9) to seal the shell from outside atmosphere, said flanged gasket sealing means
being compressed between two shell flanges and two tube sheets (6, 8) by means of
bolts inserted through the flanges, and a tube sealing means (7) to seal the tubes
from the inner shell of said heat exchanger, said tube sealing means being compressed
between said tube sheets (6, 8), characterized in that the tube sealing means (7)
is a full-face gasket and is contained around its periphery by a retaining structure
(45, 46, 47) to prevent outward radial expansion of said full-face gasket, said retaining
structure including a peripheral ring (45) which is mechanically adjustable in peripheral
length and diameter and abuts on the peripheral edge of the two tube sheets (6, 8),
so that proper compression forces are exerted on the plurality of tubes by the expanding
full-face gasket.
2. A shell and tube heat exchanger according to claim 1, wherein the peripheral ring
(45) has two clamp ring flanges (46) receiving a clamp ring bolt (47), so that the
full-face gasket (7) is entrapped by tightening said clamp ring bolt (47) and then
radially expanded without outward expansion when subsequently tightening the shell
flange bolts (40).
3. A shell and tube heat exchanger according to anyone of claims 1 and 2, wherein
the gaskets (5, 7, 9) are made of elastomeric material.
4. A shell and tube heat exchanger according to anyone of claims 1 and 2, wherein
the tube sheets (6, 8) are made of a non-compressible metal or rigid synthetic materials.
5. A shell and tube heat exchanger according to anyone of claims 1 to 4, wherein the
gaskets (5, 7, 9), flanges (4, 10), tube sheets (6, 8) and peripheral retaining structure
(45) are circular.
6. A shell and tube heat exchanger according to anyone of claims 1 to 4, wherein the
gaskets (5, 7, 9), flanges (4, 10), tube sheets (6, 8) and peripheral retaining structure
(45) are non-circular.
7. A shell and tube heat exchanger according to anyone of claims 1 to 6, wherein the
tube ends and tube gasket holes (12, 14, 16) are circular.
8. A shell and tube heat exchanger according to anyone of claims 1 to 6, wherein the
tube ends and tube gasket holes (12, 14, 16) are non-circular.
1. Mantel- und Rohrwärmeaustauscher, der einen Verlängerungsmantel (32) und einen
inneren Mantel (2), eine Mehrzahl von Rohren (3) und eine Dichtungseinrichtung aufweist,
so daß in den Rohren und in dem Mantel strömendes Fluid sich nicht vermischen kann,
welcher Flanschdichtungseinrichtungen (5, 9) aufweist, um den Mantel von der Außenumgebung
abzudichten, wobei die Flanschdichtungseinrichtung zwischen zwei Mantelflanschen und
zwei Rohrplatten (6, 8) mit Hilfe von Schrauben zusammengedrückt ist, die die Flansche
durchsetzen, wobei eine Rohrdichtungseinrichtung (7) vorgesehen ist, um die Rohre
gegen den inneren Mantel des Wärmeaustauschers abzudichten, und wobei die Rohrdichtungseinrichtung
zwischen den Rohrplatten (6, 8) zusammengedrückt ist, dadurch gekennzeichnet, daß
die Rohrdichtungseinrichtung (7) eine Vollflächendichtung ist und über ihren Umfang
hinweg mittels einer Haltekonstruktion (45, 46, 47) eingeschlossen ist, um eine radiale
Expansion der Vollflächendichtung nach aussen zu verhindern, daß die Haltekonstruktion
einen Umfangsring (45) enthält, der mechanisch in Umfangslängsrichtung und in Durchmesserrichtung
verstellbar ist und auf den Umfangsrand der beiden Rohrplatten (6, 8) anliegt, so
daß entsprechende Kompressionskräfte auf die Mehrzahl von Rohren durch die expandierende
Vollflächendichtung ausgeübt werden.
2. Mantel- und Rohrwärmeaustauscher nach Anspruch 1, bei dem der Umfangsring (45)
zwei Klemmringflansche (46) hat, die eine Klemmringschraube (47) aufnehmen, so daß
die Vollflächendichtung (7) durch Anziehen der Klemmringschraube (47) eingeschlossen
wird und sich dann radial ohne eine Expansion nach außen expandiert, wenn anschließend
die Mantelflanschschrauben (40) angezogen werden.
3. Mantel- und Rohrwärmeaustauscher nach einem der Ansprüche 1 und 2, bei dem die
Dichtungen (5, 7, 9) aus einem elastomeren Material bestehen.
4. Mantel- und Rohrwärmeaustauscher nach einem der Ansprüche 1 und 2, bei dem die
Rohrplatten (6, 8) aus einem nicht-kompressiblen Metall oder einem starren Kunststoffmaterial
hergestellt sind.
5. Mantel- und Rohrwärmeaustauscher nach einem der Ansprüche 1 bis 4, bei dem die
Dichtungen (5, 7, 9), die Flansche (4, 10), die Rohrplatten (6, 8) und die Umfangshaltekonstruktion
(45) kreisförmig sind.
6. Mantel- und Rohrwärmeaustauscher nach einem der Ansprüche 1 bis 4, bei dem die
Dichtungen (5, 7, 9), die Flansche (4, 10), die Rohrplatten (6, 8) und die Umfangshaltekonstruktion
(45) nicht-kreisförmig ausgebildet sind.
7. Mantel- und Rohrwärmeaustauscher nach einem der Ansprüche 1 bis 6, bei dem die
Rohrenden und die Rohrdichtungsöffnungen (12, 14, 16) kreisförmig ausgebildet sind.
8. Mantel- und Rohrwärmeaustauscher nach einem der Ansprüche 1 bis 6, bei dem die
Rohrenden und die Rohrdichtungsöffnungen (12, 14, 16) nicht-kreisförmig ausgebildet
sind.
1. Echangeur de chaleur tubulaire comportant un prolongement d'enveloppe (32) et une
enveloppe intérieure (2), une pluralité de tubes (3) et un moyen d'étanchéité, pour
que les fluides qui s'écoulent à travers les tubes et à travers l'enveloppe ne puissent
pas se mélanger, comportant des moyens d'étanchéité formant garniture d'étanchéité
à flasque (5, 9) pour assurer l'étanchéité de l'enveloppe à l'égard de l'atmosphère
extérieure, lesdits moyens d'étanchéité formant garniture d'étanchéité à flasque étant
comprimés entre deux flasques de l'enveloppe et deux plaques tubulaires (6, 8) au
moyen de boulons passés à travers les flasques, et comportant un moyen d'étanchéité
pour les tubes (7) pour assurer l'étanchéité du tube à l'égard de l'enveloppe intérieure
dudit échangeur de chaleur, ledit moyen d'étanchéité des tubes étant comprimé entre
lesdites plaques tubulaires (6, 8), caractérisé en ce que le moyen d'étanchéité des
tubes (7) est une garniture d'étanchéité à face pleine qui est maintenue, autour de
sa périphérie, par une structure de retenue (45, 46, 47) pour empêcher l'expansion
radiale, vers l'extérieur, de ladite garniture d'étanchéité à face pleine, ladite
structure de retenue comprenant une couronne périphérique (45) qui peut se régler
mécaniquement en longueur périphérique et en diamètre, et qui bute sur le bord périphérique
des deux plaques tubulaires (6, 8), de sorte que des forces de compression correctes
s'exercent sur la pluralité de tubes lors de l'expansion de la garniture d'étanchéité
à face pleine.
2. Echangeur de chaleur tubulaire selon la revendication 1, dans lequel la couronne
périphérique (45) présente deux rabats (46) de serrage de la couronne qui reçoivent
un boulon (47) de serrage de la couronne, de sorte que la garniture d'étanchéité à
face pleine (7) est confinée lors du serrage dudit boulon (47) de serrage de la couronne,
puis expansée radialement, sans expansion vers l'extérieur, lorsque l'on serre ensuite
les boulons (40) des flasques de l'enveloppe.
3. Echangeur de chaleur tubulaire selon l'une quelconque des revendications 1 et 2,
dans lequel les garnitures d'étanchéité (5, 7, 9) sont fabriquées en matériau élastomère.
4. Echangeur de chaleur tubulaire selon une quelconque des revendications 1 et 2,
dans lequel les plaques tubulaires (6, 8) sont fabriquées en un métal non compressible
ou en matériaux synthétiques rigides.
5. Echangeur de chaleur tubulaire selon une quelconque des revendications 1 à 4, dans
lequel la garniture d'étanchéité (5, 7, 9), les flasques (4, 10), les plaques tubulaires
(6, 8) et la structure de retenue périphérique (45) sont circulaires.
6. Echangeur de chaleur tubulaire selon une quelconque des revendications 1 à 4, dans
lequel les garnitures d'étanchéité (5, 7, 9), les flasques (4, 10), les plaques tubulaires
(6, 8) et la structure de retenue périphérique (45) sont non circulaires.
7. Echangeur de chaleur tubulaire selon l'une quelconque des revendications 1 à 6,
dans lequel les extrémités des tubes et les trous des garnitures d'étanchéité des
tubes (12, 14, 16) sont circulaires.
8. Echangeur de chaleur tubulaire selon l'une quelconque des revendications 1 à 6,
dans lequel les extrémités des tubes et les trous des garnitures d'étanchéité des
tubes (12, 14, 16) sont non circulaires.