U.S. patent application number 12/875348 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 Roland Feilner, Jorg Zacharias.
Application Number | 20110056663 12/875348 |
Document ID | / |
Family ID | 43242416 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110056663 |
Kind Code |
A1 |
Feilner; Roland ; et
al. |
March 10, 2011 |
Shell-and-Tube Heat Exchanger
Abstract
A shell-and-tube heat exchanger for the treatment of juices and
juice-type foodstuff products with medium to high viscosity, with
at least one jacket tube containing at least one inner tube,
whereby the inner tube and/or the jacket tube is or are formed as a
swirl tube with multi-start spirals running like a thread at an
angle to the tube axis, a crossed and twisted tube with crossing
spirals at least essentially symmetrical to the tube axis, each
with an angle of incidence between 67.degree. and 72.degree. to the
tube axis, i.e. with an angle of twist of 23.degree. to 18.degree.
to the tube axis, is used as an inner and/or outer tube. The spiral
depth is about 0.8 mm to 1.2 mm.
Inventors: |
Feilner; Roland;
(Regensburg, DE) ; Zacharias; Jorg; (Kofering,
DE) |
Assignee: |
KRONES AG
Neutraubling
DE
|
Family ID: |
43242416 |
Appl. No.: |
12/875348 |
Filed: |
September 3, 2010 |
Current U.S.
Class: |
165/156 |
Current CPC
Class: |
F28F 1/42 20130101; F28F
1/40 20130101; F28D 2021/0098 20130101; F28F 13/12 20130101; F28F
19/00 20130101; F28D 2021/0042 20130101; F28F 1/36 20130101; F28F
1/426 20130101; F28D 7/106 20130101 |
Class at
Publication: |
165/156 |
International
Class: |
F28D 7/10 20060101
F28D007/10 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2009 |
DE |
102009040558.5 |
Claims
1. Shell-and-tube heat exchanger for the treatment of juices and
juice-type foodstuff products with medium to high viscosity,
comprising at least one jacket tube containing at least one inner
tube, the inner tube and/or the jacket tube is or are formed as a
swirl tube with multi-start spirals running like a thread at an
angle of twist to the tube axis, and, as an inner and/or outer tube
a crossed and twisted tube is provided with mutually crossing
spirals at least essentially symmetrical to the tube axis, each
with an angle of incidence between 67.degree. and 72.degree. to the
tube axis and the angle of twist resulting from it of 18.degree. to
23.degree. perpendicular to the tube axis.
2. Shell-and-tube heat exchanger according to claim 1, wherein each
spiral has in cross-section a cavity-type indentation with ribs on
both sides and approximately wedge-shaped in cross-section, between
which, in the indentation, a spiral depth between about 0.8 mm to
1.2 mm is present.
3. Shell-and-tube heat exchanger according to claim 2, wherein the
width of the indentation viewed in the direction of the tube axis
is a multiple of the spiral depth.
4. Shell-and-tube heat exchanger according to claim 1, wherein both
multi-start spirals fully cover the tube surface.
5. Shell-and-tube heat exchanger according to claim 1, wherein the
jacket tube contains a plurality of crossed and twisted inner tubes
as the crossed and twisted tube and forms a module of the
shell-and-tube heat exchanger.
6. Shell-and-tube heat exchanger according to claim 2, wherein the
jacket tube has the indentations of the spirals on the inner side
of the tube and that the respective crossed and twisted inner tube
has the indentations of the spirals on the outer side or the inner
side.
7. Shell-and-tube heat exchanger according to claim 1, wherein
juices and juice-type products with viscosities>about 5 mPas can
be processed in the shell-and-tube heat exchanger.
8. Shell-and-tube heat exchanger according to claim 7, wherein the
juice or juice-type product is processed according to a
recuperative method with product separated against product by the
respective crossed and twisted tube.
9. Shell-and-tube heat exchanger according to claim 7, wherein the
juice or juice-type product is processed according to a method with
a heat transfer medium separated against the product by the
respective crossed and twisted tube.
10. Inner and/or jacket tube of a shell-and-tube heat exchanger for
the treatment of juices or juice-type foodstuff products with a
viscosity>about 5 mPas, comprising a crossed and twisted tube
with mutually crossing multi-start spirals at least essentially
symmetrical to the tube axis is used as an inner or jacket tube,
and that the angle of incidence (.alpha., .alpha.1) to the tube
axis is between 67.degree. and 72.degree. and the spiral depth in
the indentations formed by the spirals is between about 0.8 mm to
1.2 mm.
11. Shell-and-tube heat exchanger according to claim 2, wherein the
indentations and the ribs are arranged on the surface of the jacket
and/or inner tube in contact with the product.
12. Shell-and-tube heat exchanger according to claim 3, wherein the
width of the indentation is between about 5.0 and 20.0 mm.
13. Shell-and-tube heat exchanger according to claim 9, wherein
each spiral has in cross-section a cavity-type indentation, and the
indentations face the product.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of priority of
German Application No. 102009040558.5, 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 disclosure relates to a shell-and-tube heat exchanger of
the type used in beverage bottling operations with juices and
juice-type foods, and an inner and/or jacket tube of a
shell-and-tube heat exchanger of this type.
BACKGROUND
[0003] A shell-and-tube heat exchanger for the treatment of juices
with fibers and/or particles in which simply twisted inner and/or
outer tubes are used is known from DE 600 19 635 T2. In the inner
tube the angle of twist is shown at approximately 45.degree.,
whereas the angle of twist in the jacket tube is illustrated with
about 75.degree., referred to the tube axis in each case. With this
shell-and-tube heat exchanger a disadvantage is that to increase
the heat transfer very substantial pressure loss is accepted for a
constant area presented to the flow and the boundary layer of the
flow is induced to strong rotation at the spirals which run with
the same angle of twist to the tube axis. This requires very high
feed pressure, which may be disadvantageous for the product, for
the treatment of the product in the shell-and-tube heat
exchanger.
[0004] From DE 102 56 232 B4 a shell-and-tube heat exchanger is
known for the UHT treatment of milk and milk products for
pasteurization. The jacket tube is a smooth tube. Only the inner
tubes can be crossed and twisted tubes in which the multiple-start,
mutually opposed spirals cross at angles of incidence between
25.degree. and 35.degree. longitudinally to the tube axis, i.e. at
angles of twist between 65.degree. and 55.degree.. This angular
range is specially matched to milk and milk products which have a
very strong tendency to form deposits on the surface in contact.
Therefore, the spirals are in addition polished electrochemically.
The combination of the two measures results in optimum inhibition
of the formation of deposits of milk and milk products, giving a
longer service period of the shell-and-tube heat exchanger before a
cleaning cycle is needed. An angle of twist of 45.degree. is also
mentioned, which is regarded as optimum for the heat transfer, but
which however leads to an inadmissible heavy formation of deposits
with milk and milk products. Angles of incidence between 25.degree.
and 35.degree. and the additional surface treatment are
consequently optimum for milk and milk products with regard to the
inhibition of the product-specific formation of deposits, but, as
with the current angle of 45.degree. to the tube axis, they give an
unfavorable relationship between the increase in the heat transfer
obtained and an excessive increase in the loss of pressure in the
flow.
SUMMARY OF THE DISCLOSURE
[0005] An aspect of the disclosure is to provide a shell-and-tube
heat exchanger of the type mentioned in the introduction as well as
a jacket tube and/or inner tube for a shell-and-tube heat exchanger
of this nature, which, when processing particularly juices or
juice-type foodstuff products with low, medium or high viscosity,
facilitates optimally short dwell times and small heat exchange
surfaces despite only moderate feed pressure. This applies to all
liquid foodstuffs in this viscosity range.
[0006] Through the use of at least one crossed and twisted tube in
the shell-and-tube heat exchanger (for the jacket tube and/or each
inner tube) a substantial increase in the heat transfer is achieved
due to the crossing spirals. However, with the increase of the
pressure loss associated with the cross-twisting, the achievable
increase in the heat transfer is brought to an optimum relationship
in the through-flow by restricting the angle of incidence .alpha.
to 72.degree. to 67.degree. longitudinally to the tube axis and the
resulting angle of twist of 18.degree. to 23.degree. perpendicular
to the tube axis, i.e. to a relatively acute angle, which, despite
only moderate feed pressure, results in a smaller heat exchange
surface. In other words, due to the use of crossed and twisted
tubes of this nature, the shell-and-tube heat exchanger needs a
relatively small heat exchange surface and therefore a short
conveying distance. With juices and juice-type foodstuff products
the tendency to form product deposits is of secondary importance,
because with the use of crossed and twisted tubes with the stated
flat angles of twist the primary factor is that pulp, fibers or
particles as constituents of juices or juice-type foodstuff
products do not tend to cling and collect due to the flat angle of
twist, but are instead rapidly flushed further. Moreover, in this
way cleaning to a hygienically flawless condition is possible.
[0007] In an expedient embodiment, in the axial section of the tube
each spiral has a trough-shaped indentation with ribs on both sides
having an approximate wedge shape in cross-section, between which a
spiral depth of between about 0.8 mm to 1.2 mm is present in the
indentation. The interaction between the relatively flat angles of
twist and the moderate spiral depth results, even with a moderate
feed pressure, in a relationship between the increase in the heat
transfer and the resulting increase in the pressure loss which is
optimum for juices and juice-type foodstuff products of low, medium
and high viscosities. Preferably, the indentations and the ribs are
arranged on the surface which is in contact with the product.
[0008] In an expedient embodiment the width in the indentation,
viewed in the direction of the tube axis, is a multiple of the
spiral depth. It should be between about 5.0 and 20.0 mm. The
indentations are relatively wide cavities, on their adjacent ribs
of which constituent parts of the product are rapidly flushed
further and which also facilitate hygienically flawless cleaning,
e.g. for a change of product.
[0009] In order to be able to optimally exploit the effect of the
crossed spirals, both multi-start spirals fully cover the tube over
all the surface.
[0010] In an expedient embodiment the jacket tube as a crossed and
twisted tube with multiple crossed and twisted inner tubes forms a
module of the shell-and-tube heat exchanger. This module can extend
in an expedient manner over 3.0, 6.0 m or more and is expediently
combined with several modules in series for the treatment of the
product in the shell-and-tube heat exchanger.
[0011] In another embodiment only the inner tubes are crossed and
twisted tubes with relatively flat angles of twist, for example, if
a heat transfer medium is used in the flow channel between the
jacket tube and the inner tubes.
[0012] In another embodiment the jacket tube has the indentations
of the two spirals on the inner side of the tube, whereas the
respective crossed and twisted inner tube has the indentations of
the spirals on the outer side or the inner side, for example,
depending on along which tube surface the product flows.
[0013] The shell-and-tube heat exchanger is particularly well
suited to the treatment of juices or juice-type foodstuff products
with viscosities>about 5 mPas.
[0014] For the treatment of the relevant product two different
methods present themselves, i.e. either a recuperative method in
which product is processed against product separated by the
respective crossed and twisted tube, e.g. in counterflow, or a
method with a heat transfer medium against the product separated by
the respective crossed and twisted tube, whereby then, preferably,
the indentations of the two spirals of the crossed and twisted tube
face the product.
[0015] The crossed and twisted tubes used are expediently stainless
steel tubes on which both spirals act on the flows on the inner and
outer tube surfaces.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Embodiments of the disclosure are explained based on the
drawings. The following are shown:
[0017] FIG. 1 a shell-and-tube heat exchanger for the heat
treatment of juices or juice-type foodstuff products with an
example of a module with a crossed and twisted tube as jacket
tube,
[0018] FIG. 2 another embodiment of a module with at least one
inner tube as a crossed and twisted tube in, for example, a smooth
jacket tube,
[0019] FIG. 3 a further embodiment of a module in which the jacket
tube and each inner tube are formed as crossed and twisted
tubes.
[0020] FIG. 4 a detailed section of the tube wall of a crossed and
twisted tube with indentations of both spirals facing the inside of
the tube, and
[0021] FIG. 5 a cross-section of the tube wall of a crossed and
twisted tube with indentations of both spirals located on the outer
side of the tube.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0022] FIG. 1 illustrates a module M of a shell-and-tube heat
exchanger W for the heat treatment of juices or juice-type
foodstuff products with medium to high viscosities, for example, a
viscosity of more than about 5 mPas, which comprises a jacket tube
1 and at least one approximately coaxial inner tube 2 accommodated
inside the jacket tube 1 and spaced from the inner wall of the
jacket tube 1. In the shell-and-tube heat exchanger W the module M
is, for example, combined with further modules of the same type or
similar which are not illustrated in order to form a treatment
section of a certain conveying length. The product is either
treated according to a recuperative method, i.e. product separated
against product, for example, by the inner tube 2, or according to
a method in which a heat transfer medium (steam or water) is used,
whereby the heat transfer medium is separated against the product,
for example, by the relevant inner tube 2. The relevant method is
preferably operated in counterflow or uniflow.
[0023] The jacket tube 1 in FIG. 1 is formed as a crossed and
twisted tube with multi-start spirals D1, D2 crossing one another
essentially symmetrical to the tube axis X, whereby the angle of
incidence .alpha. to the tube axis X is between 67.degree. and
72.degree. and the resulting angle of twist .beta. is 18.degree. to
23.degree. perpendicular to the tube axis. The crossed and twisted
tube is, for example, similar to that illustrated in FIG. 4 with
the indentations 3 facing the inside of the tube. In FIG. 1 the
respective inner tube 2 is either a smooth tube or similarly a
crossed and twisted tube with essentially multi-start, mutually
crossing spirals symmetrical to the tube axis X and with angles of
twist .beta.1 between 18.degree. and 23.degree..
[0024] In the embodiment in FIG. 2 of the module M the jacket tube
1 is a smooth tube. In contrast each inner tube 2 contained in the
jacket tube 1 is a crossed and twisted tube with multi-start,
mutually crossing spirals D1, D2 essentially symmetrical to the
tube axis X and with angles of incidence .alpha.1 between
67.degree. and 72.degree. to the tube axis. The spirals D1, D2 are
multi-start, so that despite the relatively steep angle of
incidence .alpha.1 (angle of twist .beta.1 between 18.degree. and
23.degree.), the complete tube surface is offered to the product,
primarily the macro-structures which intensify the heat transfer,
and the optimum is obtained between the increase in the heat
transfer and the pressure loss due to the spirals.
[0025] In the embodiment in FIG. 3 of the module M crossed and
twisted tubes with multi-start, mutually crossing spirals D1, D2
essentially symmetrical to the tube axis X are used for the jacket
tube 1 and each inner tube 2, whereby here too the angle of twist
.beta., .beta.1 is between 18.degree. and 23.degree. perpendicular
to the tube axis X.
[0026] An angle of twist .beta., .beta.1 of 18.degree. to
23.degree. to the tube axis means an angle of incidence .alpha.,
.alpha.1 of each spiral of .beta., .beta.1=90.degree.-angle of
twist=.alpha., .alpha.1=67.degree. to 72.degree. referred to a
plane longitudinal to the tube axis X.
[0027] FIG. 4 illustrates the macro-structures formed as the jacket
tube and/or inner tube 1, 2 by the crossing spirals D1, D2 of the
respective crossed and twisted tube, which are present on the inner
side and the outer side of the tube. In FIG. 4 the cavity-type
indentations 3, which are in each case bounded by essentially
wedge-shaped ribs 5 and have a spiral depth T between 0.8 mm and
1.2 mm, are provided facing the tube axis X and following one
another in the axial direction. The width B of each indentation 3
is a multiple of the spiral depth T, preferably between 5.0 mm and
20.0 mm. On the outer side of the tube and corresponding to the
indentation 3, a rounded dome 4 is provided which is bounded in the
axial direction by approximately V-shaped grooves 6. In an
alternative which is not illustrated the ribs 5 and the grooves 6
can be rounded, for example with a view to easy tube cleaning. The
ribs 5 or the grooves 6, as well as the indentations 3 and the
domes 4, run over the complete inner, respectively outer tube
surface at an angle of incidence .alpha., .alpha.1 like a thread
and cross one another periodically.
[0028] In the embodiment in FIG. 5 a crossed and twisted tube is
shown as a jacket or inner tube 1, 2 on which the indentations 3
are present on the outer side of the tube (i.e. facing away from
the tube axis X). In this respect the rounded domes 4 and the
grooves 6 face the tube axis X. The spiral depth T is between 0.8
mm and 1.2 mm. The angle of twist .beta., .beta.1 is between
18.degree. and 23.degree. to the tube axis X. The crossed and
twisted tube illustrated in FIG. 5 can be expediently used as inner
tube 2, if, for example, the product flows between the jacket tube,
which is designed as in FIG. 4, and the outer side of the inner
tube 2. If a heat transfer medium is being used, which flows in the
flow channel between the jacket tube 1 and the inner tube 2, the
crossed and twisted tube of the inner tube 1, 2 is expediently
formed analogously to FIG. 4.
[0029] From the use of the crossed and twisted tubes with an angle
of incidence .alpha., .alpha.1 of 67.degree. to 72.degree. and a
spiral depth T between 0.8 mm and 1.2 mm for a spiral width B
between about 5.0 mm and 20.0 mm, an optimum relationship results
between the increase in the heat transfer achievable by the crossed
spiral technique or the heat transfer coefficient and the increase
in pressure loss which has to be accepted for the through-flow for
medium or highly viscous juices or juice-type foodstuff products,
such that the respectively applied method (recuperative or with
heat transfer medium) requires a relatively small heat exchange
surface for only moderate feed pressure with short dwell times in
the shell-and-tube heat exchanger, or a relatively short conveying
section is sufficient for the shell-and-tube heat exchanger W.
* * * * *