U.S. patent application number 12/875341 was filed with the patent office on 2011-03-10 for shell-and-tube heat exchanger.
This patent application is currently assigned to KRONES AG. Invention is credited to Jorg Zacharias.
Application Number | 20110056653 12/875341 |
Document ID | / |
Family ID | 43242408 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110056653 |
Kind Code |
A1 |
Zacharias; Jorg |
March 10, 2011 |
Shell-and-Tube Heat Exchanger
Abstract
A shell-and-tube heat exchanger including a casing tube and at
least one inner tube for treating liquid food products, optionally
also with a product/product flow guidance, and having at least one
thermal-expansion compensating device for the casing and/or inner
tube, with the compensating device having a surface which can be
contacted by the product to be treated, where the surface is
provided on a bellows integrated into the casing and/or inner tube,
with a plurality of relatively wide folds which extend around the
tube axis and are of rounded cross-section, with the respective
fold being configured with a radial depth and an axial width with a
ratio of B:T of about 1 or more and to be cleanable on the product
side in a hygienically irreproachable way.
Inventors: |
Zacharias; Jorg; (Kofering,
DE) |
Assignee: |
KRONES AG
Neutraubling
DE
|
Family ID: |
43242408 |
Appl. No.: |
12/875341 |
Filed: |
September 3, 2010 |
Current U.S.
Class: |
165/83 ;
165/158 |
Current CPC
Class: |
F28F 2265/26 20130101;
F28D 2021/0042 20130101; F28F 1/08 20130101; F28D 7/10 20130101;
F28D 7/16 20130101 |
Class at
Publication: |
165/83 ;
165/158 |
International
Class: |
F28D 1/053 20060101
F28D001/053; F28F 7/00 20060101 F28F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2009 |
DE |
102009040560.7 |
Claims
1. A shell-and-tube heat exchanger, comprising a casing tube, at
least one inner tube for treating liquid food products,
particularly low-viscosity products, such as juices or milk, also
with a product/product flow guidance, at least one
thermal-expansion compensating device for the casing and/or inner
tube, with the compensating device having disposed therein at least
one surface which can be contacted by the product to be treated, on
at least one bellows integrated into the casing and/or inner tube
the surface which can be contacted by the product is provided with
a plurality of relatively wide folds which extend around the tube
axis and are of rounded cross-section, and that the respective fold
is configured on the surface which can be contacted by the product
with a radial depth and an axial width with a ratio of B:T of about
1 or more and can thereby be cleaned in a hygienically
irreproachable way.
2. The shell-and-tube heat exchanger according to claim 1, wherein
the ratio of B:T, at least on the surface which can be contacted by
the product, ranges from about 1 to about 2.
3. The shell-and-tube heat exchanger according to claim 1, and a
plurality of axially directly successive, alternatingly inwardly
and outwardly shaped, at least substantially similar folds are
provided with the ratio of B:T of about 1 or more.
4. The shell-and-tube heat exchanger according to claim 1, and a
plurality of relatively wide folds which are axially successive
with interspaces and substantially of a similar kind are provided
inwards or outwards and are formed on the surface which can be
contacted by the product with the ratio B:T of about 1 or more, and
that narrower folds are provided in the interspaces, the narrower
folds being configured with a ratio of B1:T of less than 1.
5. The shell-and-tube heat exchanger according to claim 1, wherein
the inner diameter of the bellows has a size that is between
approximately the inner diameter of the inner or casing tube
including the bellows and the inner diameter less the depth.
6. The shell-and-tube heat exchanger according to claim 1, wherein
the bellows comprises substantially circular cylindrical tube
sockets which are welded to the inner or casing tube and which are
inserted in or over inner-tube or casing-tube section ends.
7. The shell-and-tube heat exchanger according to claim 1, wherein
the bellows is formed by a roller treatment or by hydraulic
formation integrally in the per se circular cylindrical wall of the
inner and/or casing tube.
8. The shell-and-tube heat exchanger according to claim 1, wherein
the casing tube forms a heat-exchanger module with a plurality of
inner tubes, and that the bellows is arranged approximately in the
longitudinal center of the heat-exchanger module on relatively wide
folds with the ratio of B:T of about 1 or more.
9. The shell-and-tube heat exchanger according claim 1, and wherein
on the surface which can be contacted by the product the fold has a
harmonious surface extension that promotes substantially turbulent
flow conditions such that the flow encompasses all depths of the
bellows.
10. The shell-and-tube heat exchanger according to claim 1, wherein
each fold is formed in an axial section of the inner or casing tube
of curvature sections continuously passed into one another.
11. The shell-and-tube heat exchanger according to claim 3, wherein
the plurality of at least substantially similar folds is up to six
or more folds.
12. The shell-and-tube heat exchanger according to claim 3, wherein
the plurality of at least substantially similar folds are convexly
rounded to the outside.
13. The shell-and-tube heat exchanger according to claim 1, wherein
the bellows is arranged in the casing tube and with the surface
which is oriented towards the inner tubes and can be contacted by
the product.
14. The shell-and-tube heat exchanger according to claim 10,
wherein the curvature sections have circular-arc sections with a
radius of curvature corresponding to about half the depth and/or
width.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of priority of
German Application No. 102009040560.7, filed Sep. 8, 2009. The
entire text of the priority application is incorporated herein by
reference in its entirety.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to a shell-and-tube heat
exchanger of the type used for treating liquid foods.
BACKGROUND
[0003] Shell-and-tube heat exchangers e.g. for product/product flow
guidance are known from DE 600 19 635 T2 and DE 102 56 232 B4. The
heat-expansion compensating device is here a slide connection with
seals or a floating or moveable bearing permitting thermally caused
relative movements, but creating dead spaces in which the product
can settle in such a way that despite intensive cleaning it cannot
be removed any more, or requires a dismantling operation for
hygienically irreproachable cleaning. Under hygienic aspects such
compensating devices are not recommended by the authorities in
charge, but have so far been common as a comprise solution for the
product/product flow guidance.
[0004] By contrast, in shell-and-tube heat exchangers in the food
industry, in which flow guidance of product/heat carrier medium
(e.g. water) takes place, it is known that at least one bellows is
installed as a thermal-expansion compensating device in such a way
that it is exclusively contacted by the heat-carrier medium, but
definitely not by the product. After specific periods of use of the
shell-and-tube heat exchanger, or during product change, the
bellows will not be cleaned because it has only been in contact
with the heat carrier medium at any rate. The bellows is
deliberately configured with a ratio of B:T of very much less than
1, optionally with straight flanks and very small radii of
curvatures between the flanks, because it is in this way that the
compensatory action per fold is strong and the number of folds that
is needed is thus as small as possible. On account of the ratio of
B:T of very much less than 1, which is of advantage to
compensation, this bellows could no longer be cleaned to obtain a
hygienically irreproachable condition because inevitably firmly
sticking product deposits would arise upon contact with a product
e.g. due to swirl formations and dead zones.
SUMMARY OF THE DISCLOSURE
[0005] One aspect of the present disclosure to configure a
shell-and-tube heat exchanger of the aforementioned type for
product/product flow guidance in a way that it can be cleaned in a
hygienically irreproachable way.
[0006] The deliberate turning away from a fold B:T ratio that is
usually standard for an optimum heat expansion compensation and the
adoption of a ratio of B:T of about 1 or more, which is less
advantageous for compensation, at least on the surface of the fold
that can be contacted by the product, makes it possible that the
surface that can be contacted by the product can be cleaned for
achieving a hygienically irreproachable state of the product
because there are relatively moderate directional changes in the
rounded folds and relatively weakly curved surfaces and there are
no critical dead spaces. Hence, the product is less prone to
sticking, but is always swiftly flushed out of the fold. Cleaning
media can efficiently eliminate product residues and the media
themselves can be flushed out easily and/or removed without any
residues. To accomplish the compensatory action required on the
whole, one need only provide a corresponding additional number of
folds. This, however, is certainly acceptable with respect to the
achievable, hygienically irreproachable conditions for the
product/product flow guidance and hermetic tightness in the
shell-and-tube heat exchanger. Due to the accepted deterioration of
the compensatory action of each fold, which contacts the product
e.g. with its inside and is provided as such for the technical
purpose of compensating heat expansions, it is only now that the
bellows is given the hygienic qualification for the product/product
flow guidance in the shell-and-tube heat exchanger, also for the
reason that a harmonious surface extension achieves very
advantageous flow conditions that drastically improve the cleaning
efficiency in particular. Hence, a shell-and-tube heat exchanger
with hygienic bellows is accomplished.
[0007] In an expedient embodiment the ratio of B:T may e.g. be
about 1 up to about 2. The greater the ratio, the more advantageous
is the fold during cleaning after predetermined operating periods
or with respect to a product change.
[0008] In an expedient embodiment, several folds are provided in
the bellows; these folds are directly successive in axial
direction, they are formed alternatingly inwards and outwards and
they are at least substantially similar and relatively wide.
Whenever this bellows is arranged in the casing tube, the surface
which can be contacted by the product is only present on the
inside. By contrast, if the bellows is arranged in an inner tube,
the inner or the outer surface or both surfaces can be contacted by
the product, with optimum conditions being each time provided for
the cleaning action.
[0009] In an alternative embodiment, a plurality of folds that are
axially successive with interspaces and substantially similar are
provided inwards or outwards; the folds are formed with the ratio
of B:T of about 1 or more on the surface which can be contacted by
the product, and folds which are given a ratio of B1:T<1 are
provided in the interspaces. It is recommended in this embodiment
that the convexly curved surfaces of the folds should be arranged
with the ratio of B1:T<1 on the bellows surface which can be
contacted by the product, because these convex surface sections can
also be cleaned easily. This constitutes a hybrid configuration of
the bellows, on the one hand to be able to clean the concave
surface sections of the relatively wide folds with the ratio of B:T
of about 1 or more without difficulty, but also to achieve a
smaller compensatory action per length unit, and on the other hand
to be able to achieve an adequately good cleaning action also on
the convex surface portions of the folds with the ratio of
B1:T1<1, but to obtain a stronger compensatory action per length
unit at said place. As has been stated, this hybrid form of the
bellows is specifically recommended for the casing tube if said
tube is contacted by the product on the inner surface.
[0010] In another embodiment, the inner diameter of the bellows has
a size which lies between approximately the inner diameter of the
inner or casing tube comprising the bellows and said inner diameter
less the depth of the folds. Depending on the specific application
of the bellows in the casing tube or in an inner tube, undesired
constrictions within said bellows/inner diameter region can be
avoided or minimized in the respective flow channels.
[0011] In one embodiment the bellows comprises substantially
circular cylindrical tube sockets welded to the inner or casing
tube, which are inserted in or over section ends of the inner or
casing tube. Integrating the bellows into the respective tube can
be easily mastered by way of production technology. The welds are
tight and can withstand high pressure differences without any
problems. The bellows can be arranged at the respectively optimum
position of the tube.
[0012] In an alternative embodiment, the bellows is integrally
formed in the circular cylindrical wall of the respective tube,
e.g. by roller treatment or by hydraulic formation. Weld joints are
thereby no longer needed.
[0013] In an expedient embodiment a casing tube forms a
shell-and-tube heat exchanger module with a plurality of inner
tubes. The bellows, at least one bellows, can be arranged
approximately in the longitudinal center of the heat-exchanger
module so as to develop its compensatory action in an optimum way.
Preferably, the bellows is positioned in the casing tube in such a
way that the surface of the bellows which can be contacted by the
product is oriented towards the inner tubes which are accommodated
in the casing tube and may be smooth.
[0014] It is important for an efficient cleaning when at least on
the surface which can be contacted by the product the fold has such
a harmonious surface extension that essentially turbulent flow
conditions are promoted there, such flow conditions completely
encompassing all recesses of the bellows. Essentially turbulent
flow conditions offer the advantage that no zones are formed where
it must be feared that not only the product will deposit, but a
cleaning medium is also not in a position to develop an efficient
cleaning action.
[0015] Particularly expediently, each fold is formed in an axial
section of the inner and/or casing tube which is equipped with the
bellows and consists of curvature sections continuously passed into
one another. Preferably, this regards circular-arc sections with a
radius of curvature corresponding approximately to half the depth
and/or width of the respective fold.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Embodiments of the subject matter of the disclosure shall
now be explained in more detail with reference to the drawings, in
which:
[0017] FIG. 1 is a schematic longitudinal section through a module
of an exemplary shell-and-tube heat exchanger;
[0018] FIG. 2 shows, on an enlarged scale, a detail of FIG. 1 with
a bellows in a casing tube of the shell-and-tube heat exchanger
module;
[0019] FIG. 3 is an axial section of another embodiment, e.g. a
casing tube or an inner tube of a module;
[0020] FIG. 4 is an axial section of another embodiment of a casing
tube or an inner tube of a module; and
[0021] FIG. 5 is a partial section of a specific embodiment of a
module.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] Each of FIGS. 1 and 5 illustrates an individual module M of
a shell-and-tube heat exchanger W shown in broken line, as is e.g.
used in the bottling or filling industry for liquid food products
(e.g. water, juices, milk) for a product/product flow guidance in
the heat treatment (heating or cooling) of a food product. In the
shell-and-tube heat exchanger W it is possible to install a
plurality of modules so as to obtain flow paths for the product
that are as long as possible. Module M may here have a length of
e.g. 3.0 m, 6.0 m, or even more.
[0023] In FIG. 1 the module M comprises a casing tube 1, e.g. of
stainless steel, which comprises end-sided fastening flanges 2 for
installation in the shell-and-tube heat exchanger W. In the casing
tube 1 at least one inner tube 3 is provided that extends
substantially axially parallel with respect to the casing tube 1
between fastening flanges 4. In the embodiment in FIG. 1, several
inner tubes 3 are provided that are combined to form a tube bundle,
so that at least the flow channels 5, 6, 7 and 8 are defined
between the casing tube 1 and the inner tubes 3 and also in the
inner tubes 3, with the channels 6, 7 and 8 pertaining to a primary
flow and the channel 5 belonging to a secondary flow channel. In
these flow channels the food product is circulating, and at least
one flow path is here optionally also used for a heat carrier
medium (in FIG. 1 e.g. the flow path 5). To be able to compensate
for unavoidable thermal expansions between the tubes 1, 3, which
are caused by different temperatures prevailing in the flow paths,
a compensating device K, which is configured as a bellows C with a
plurality of folds F, is integrated in the casing tube 1 in the
embodiment in FIG. 1. It would certainly be possible to provide a
plurality of bellows C over the length of the module M (e.g. 6.0 m
or more). The bellows C shown in FIG. 1 is provided on the inside
with a surface 12 which can be contacted by the product in the flow
path 5, and the bellows compensates for the different axial heat
expansions of the casing tube 1 in relation to the axial heat
expansions of the inner tubes 3 by way of predominantly axial
operation. In FIG. 5 open end flanges 2 are provided on the casing
tube 1 for the connection of e.g. the inner tubes 3, and lateral
connections 2' are provided in the casing tube 1.
[0024] The inner tubes 3 could also be equipped with bellows C in
addition, or only the inner tubes 3; in this case a bellows C in an
inner tube 3 presents, optionally on the inside and/or outside, a
surface 12 which can be contacted by the product.
[0025] FIG. 2 shows the bellows C of FIG. 1 on an enlarged scale.
The bellows C is welded with end-sided, e.g. circular cylindrical,
tube sockets 10 to the casing tube 1, i.e. here inserted into
casing tube section ends 1a, 1b on the inside and welded at 11.
Alternatively, the tube sockets 10 could also be attached on the
outside onto the casing-tube section ends 1a, 1b and welded. The
bellows C is prefabricated and installed in the casing tube 1 at a
later time.
[0026] The bellows C in FIG. 2 is distinguished in that it
comprises a plurality of relatively wide folds F that are arranged
axially with interspaces one after the other and extend around the
tube axis X and have a radial depth T and an axial width B and are
similar to one another. The ratio of B:T is about 1 or is even
greater, up to preferably about 2 at the most. The surface 12 that
can be contacted by the product is mainly concavely rounded and
extends relatively harmoniously with e.g. a radius of curvature R1,
which may be about half the depth T or the width B.
[0027] Opposite folds F1' are provided in the interspaces between
the axially spaced-apart folds F; on the surface 12 which can be
contacted by the product, the folds F1' have each a convex surface
section with a radius of curvature R2' which is smaller than half
the depth T or the width B and may be about half the width B1 of
the fold F1'.
[0028] The inner diameter of the bellows C is designated with d and
approximately corresponds to the inner diameter D of the casing
tube 1. The outer diameter D1 of the bellows C corresponds
approximately to the inner diameter d plus two times the depth T
and plus the material thickness of the bellows C. Like the casing
tube 1, the bellows C consists preferably of stainless steel. The
inner tubes 3 are not shown in FIG. 2. The exterior surface 9 of
the bellows C does not get into contact with the product in module
M.
[0029] In the embodiment in FIG. 3, the bellows C is integrated
either into the casing tube 1 or into the respective inner tube 3.
When the bellows C is positioned in the inner tube 3, the inner and
outer surfaces 12 can then be contacted by the product in this
instance. In the bellows C, a plurality of axially directly
successive, alternatingly inwardly and outwardly shaped folds F, F1
are formed; these may be similar and have successively convex and
concave curvatures, expediently with radii of curvature R1, R2
corresponding to about half the depth T. Expediently, these are
circular sections, preferably semicircles, continuously passed into
one another. The inner diameter d1 of the bellows C corresponds to
about the inner diameter d of the casing or inner tube 1, 3 or the
outer diameter d thereof whereas the outer diameter D1 of the
bellows corresponds approximately to the outer diameter D plus two
times the depth T and the material thickness. In the illustrated
embodiment for an inner or casing tube 1, 3 with an outer diameter
D of about 70.0 mm, the width B of each fold is just below 10.0 mm;
the depth T of each fold is also about 10.0 mm, and six folds F and
five folds F1 are provided over the length of the bellows C.
[0030] In the embodiment in FIG. 4, the inner diameter d1 of the
bellows C is smaller than the inner diameter d of the casing or
inner tube 1, 3, smaller preferably up to not more than about the
depth T, and the outer diameter D1 of the bellows C is slightly
larger than the outer diameter D or almost as large as the outer
diameter D. Likewise in the bellows C in FIG. 4, a plurality of
folds F, F1 are provided in axially direct succession alternatingly
inwardly and outwardly; these folds may be similar.
[0031] In the embodiment of FIG. 4, the outer diameter D is about
114.0 mm, the length of the bellows C is about 146.0 mm, the depth
T is about 12.0 mm and the width B is about 11.0 mm.
[0032] In each embodiment the ratio B:T of the fold F, F1 is chosen
to be about 1.0 or greater, preferably up to not more than about
2.0.
[0033] The ratio may here be slightly smaller than 1, but
preferably always more than 0.9.
[0034] Preferred embodiments have casing diameters of up to 250 mm.
There may however also be shapes with larger diameters.
* * * * *