(19) |
|
|
(11) |
EP 0 124 584 B1 |
(12) |
EUROPEAN PATENT SPECIFICATION |
(45) |
Mention of the grant of the patent: |
|
27.04.1988 Bulletin 1988/17 |
(22) |
Date of filing: 18.10.1983 |
|
(86) |
International application number: |
|
PCT/US8301/635 |
(87) |
International publication number: |
|
WO 8401/818 (10.05.1984 Gazette 1984/12) |
|
(54) |
IMPROVEMENTS IN OR RELATING TO FLUID HANDLING APPARATUS
VERBESSERUNGEN AN ODER BETREFFEND FLUIDABEHANDLUNGSVORRICHTUNGEN
AMELIORATIONS AUX APPAREILS DE MANIPULATION DE FLUIDES
|
(84) |
Designated Contracting States: |
|
AT BE CH DE FR GB LI NL SE |
(30) |
Priority: |
01.11.1982 US 438300
|
(43) |
Date of publication of application: |
|
14.11.1984 Bulletin 1984/46 |
(73) |
Proprietor: VAPOR CORPORATION |
|
Chicago, IL 60648 (US) |
|
(72) |
Inventor: |
|
- HOLL, Richard, A.
Mission Viejo, CA 92691 (US)
|
(74) |
Representative: Lawson, David Glynne et al |
|
Marks & Clerk
57-60 Lincoln's Inn Fields GB-London WC2A 3LS GB-London WC2A 3LS (GB) |
(56) |
References cited: :
EP-A- 0 042 613 FR-A- 446 438 GB-A- 730 375 US-A- 155 936 US-A- 1 313 624 US-A- 2 070 427 US-A- 4 211 277
|
FR-A- 367 584 FR-A- 1 249 001 GB-A- 2 069 676 US-A- 1 283 550 US-A- 2 034 822 US-A- 2 709 128
|
|
|
|
|
|
|
|
|
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).
|
Field of the invention
[0001] This invention is concerned with improvements in or relating to fluid handling apparatus,
such as heat exchanger apparatus and fluid reactor apparatus.
Review of the prior art
[0002] It is of course a constant aim in all fields of manufacture to lower costs both of
the apparatus itself and of its cost of operation and maintenance. In the case of
heat exchange apparatus there is therefore a constant endeavour to improve efficiency,
so that the cost of operation is reduced directly and so that the apparatus is smaller
in size, which in itself is usually a desirable characteristic, such size reduction
resulting in a requirement for less material in its fabrication. This reduction in
material requirement is especially important in apparatus employed with corrosive
fluids and in difficult environments when expensive corrosion-resistant materials
must be used. It is also an endeavour to provide as great a freedom as possible from
fouling, together with ease of assembly and disassembly, so as to give accompanying
consequent economy in maintenance. There are similar advantages to be obtained in
the case of fluid reaction apparatus, resulting from increases in efficiency of the
fluid mixing and efficiency of contact with catalytic material, and also in the case
of fluid reaction apparatus that has heat exchange capa- 'bility to take account of
the exothermic or endothermic nature of the reactions involved.
[0003] EP-A-42613 corresponding to US―A―4593754 describes an improved heat exchange process
and apparatus, specifically apparatus in which a fluid flows along a solid surface,
for example for heat exchange or reaction, in which a flow-modifying structure is
placed in the fluid flow path adjacent the solid surface, which flow-modifying structure
comprises a plurality of interrupter elements spaced in the direction of flow, each
interrupter element is of at least approximately spherical profile, as seen in side
elevation, and the interrupter elements touch or nearly touch the surface in such
a manner that they locally establish non-turbulent interruptions of the fluid flow
at the surface while establishing mixing zones in the main body of the fluid spaced
from the surface.
[0004] In this process and apparatus the fluid flow takes the form of a non-turbulent boundary
layer or layers immediately adjacent to the heat transfer source and a non-turbulent
core layer interfacing with the boundary layer or layers. An interrupter structure
is provided within the flow passage to interrupt in as non-turbulent a manner as possible
the said boundary layer or layers at a plurality of spaced interruption spots, whereby
parts of the interrupted boundary layer separate from the heat transfer surface and
mix with the core layer to effect heat 'transfer between the surface and the core
layer. This structure consists of densely-packed convex sphere segments each arranged
with a part of its convex surface touching or almost touching the heat transfer surface.
Such a structure provides a very high coefficient of heat transfer without a disproportionate
increase in the pumping power required to move the fluid through the apparatus.
[0005] The object of the present invention is to provide a fluid handling apparatus, in
particular heat exchange apparatus, in which the contact between the flowing fluid
and the adjacent solid surface is further enhanced, whereby in particular the coefficient
of heat transfer can be further increased.
[0006] The present invention provides a fluid handling apparatus in which a fluid flows
along a solid surface, for example for heat exchange or reaction, in which a flow-modifying
structure is placed in the fluid flow path adjacent the solid surface, which flow-modifying
structure comprises a plurality of interrupter elements spaced in the direction of
flow, each interrupter element is of at least approximately spherical profile, as
seen in side elevation, and the interrupter elements touch or nearly touch the surface
in such a manner that they locally establish non-turbulent interruptions of the fluid
flow at the surface while establishing mixing zones in the main body of the fluid
spaced from the surface, characterised in that each interrupter element comprises
a plurality of blade-like members which extend radially outwards relative to one another,
whereby the boundary layer is locally interrupted by the tips of the blades at points
which are spaced both laterally and longitudinally relative to the fluid flow direction.
[0007] Preferably, the spacing between immediately successive interrupter elements is such
as to produce wake interference flow in the fluid.
[0008] Particularly good heat transfer performance is achieved if each blade-like member
is thicker at its root than at its tip, and tapers progressively, radially outwards
from the root to the tip.
[0009] Preferably the structure comprises an axial core element to which the interrupter
elements are connected and along which the interrupter elements are spaced.
[0010] The fluid handling apparatus may comprise heat exchange apparatus in which the interrupter
elements are disposed adjacent the surface of a wall through which heat exchange takes
place.
[0011] The fluid handling apparatus may comprise a fluid reactor in which the interrupter
structure is coated with a material exhibiting reactive and/or catalytic properties
toward the fluid.
[0012] The invention has a particularly useful application to heat exchange apparatus of
the shell and tube type. Preferably, each tube has at least one further interrupter
structure in contact with its external surface through which surfave heat exchange
takes place to fluid in the shell.
[0013] Preferably each external interrupter structure comprises an elongated axial core
element extending in the direction of fluid flow of the fluid, and
[0014] a plurality of spaced spherical interrupter elements extending along the said core
element.
[0015] Fluid handling apparatus constituting preferred embodiments of the invention will
now be described, by way of example, with reference to the accompanying diagrammatic
drawings, wherein:
Figure 1 is a longitudinal section through a heat exchanger embodying the invention,
taken on the line 1-1 of Figure 2, parts only of some of the tubes thereof being shown
broken away and parts of structures being shown in phantom to avoid excessive detail;
Figure 2 is a part transverse section through the apparatus of Figure 1, taken on
the line 2-2 of Figure 2, only the lower right quadrant being shown in full to avoid
excessive detail;
Figure 3 is a transverse cross-section to an enlarged scale of an interrupter element
of the apparatus of Figures 1 and 2;
Figures 4A, 4B and 4C are respective side elevations to an enlarged scale, and showing
interrupter elements of different profiles;
Figure 5 is a longitudinal cross-section through a single tube illustrating the fluid
flow therethrough past an interrupter element;
Figure 6 is a longitudinal section similar to Figure 1, showing an interrupter structure
of another kind, and applied to fluid reaction apparatus of the invention; and
Figure 7 is a plot of ranking of different heat exchanger surface, including a surface/structure
combination of the invention.
Description of the preferred embodiments
[0016] The heat exchanger of Figures 1 and 2 is of shell-and-tube type comprising a central
shell member 10 having inlet 12 and outlet 14 for the fluid that is to pass in the
shell around the outside of the tubes. The two ends of the shell member 10 are closed
by two respective tube sheet assemblies, each consisting of two spaced tube sheets
16 and 18 through which pass the ends of a plurality of parallel tubes 20 so as to
be supported by the tube sheets. The joints between the tubes and the apertures in
the tube sheets through which they pass, and also the joints between the tube sheet
assemblies and the adjacent shell members, are sealed by specially shaped unitary
gaskets 22 and 24. Any of the two fluids that leak through the gaskets enters the
space between the tube sheets and can be vented to atmosphere without cross- contamination
of the fluids.
[0017] Two subsidiary like end members 26 and 28 are mounted on the respective ends of the
central shell member 10 abutting the respective tube sheet assemblies to form respective
plenums for the fluid that enters and discharges from the interiors of the tubes 20,
and are provided respectively with inlet 30 and outlet 32 for such fluid. The ends
of the shell end members 26 and 28 are closed by respective end plates 34 held to
the members by respective encircling removable split rings 36 and tensioned band clamps
38. The tube sheet assemblies and the subsidiary members are manner by means of encircling
split rings 40 and tensioned band clamps 42, the split rings having radially inwardly
extending projections that engage in respective circumferential grooves in the shell
members.
[0018] Each tube 20 has mounted therein a respective fluid flow interrupter structure 44
of the invention comprising a plurality of longitudinally spaced interrupter elements
46, which in this embodiment are mounted longitudinally spaced from one another along
the length of the tube on an elongated axial core element rod 48. The ends of this
rod are free of the interrupter elements and extend out of the tubes 20 through the
respective plenums into contact with the adjacent faces of the removable end plates
34, so that the interrupter structures are maintained in fixed longitudinal positions
in the tubes.
[0019] As is seen most clearly in Figure 2 and 3, each interrupter element 46 consists of
a plurality of equal length blade like members 50 extending mutually radially outwards
from the core rod 48 until they touch, or at least almost touch, the inside cylindrical
wall of the respective tube. As is seen most clearly in Figures 1, 4, and 5 each blade
like member is of convex curvilinear profile as seen in side elevation, so that it
has only effectively a point 52 of its circumference in contact with the tube inner
wall, or immediately adjacent thereto.
[0020] It is known to those skilled in the art that a fluid flowing within a passage, such
as a tube 20, has a very thin virtually stationary boundary layer at the tube inner
wall which insulates the wall surface from the main body of the fluid flowing in a
core layer interfacing with the boundary layer, the boundary layer therefore reduces
the heat transfer between the tube inner surface and the core layer. It is also known
that an unobstructed boundary layer increases progressively in thickness in the direction
of fluid flow, which will increase its insulating effect. Proposals have therefore
been made hitherto to disprupt such boundary layers by roughening or ridging the surfaces
over which they flow, but such proposals have the effect of also increasing in a disproportionately
greater extent the pumping power required to move the fluid through the passage because
of the turbulence that is generated in the fluid.
[0021] In apparatus of the invention the boundary layer at the tube inner faces is interrupted
in a "spot-wise" manner at circumferentially and longitudinally spaced spots by means
of the fluid flow interrupter structure of the invention, while maintaining a non-turbulent
fluid flow in the main body of the fluid constituted by the core layer. In the apparatus
of the invention not only are the heat transfer surfaces not roughened, etc., but
on the contrary they are made as smooth as is economically possible, to the extent
that in some embodiments both the inner and the outer surfaces of the tubes 20 may
be polished to the desired degree of smoothness. The disruption of the boundary layer
at the multitude of spaced spots ensures that it stays thin, while the manner of its
disruption ensures thatturbuience is avoided that would cause unduly high friction
drag.
[0022] It will be noted that the blade-like members of the interrupter elements are relatively
thick at their root connections with the axial core rod and taper smoothly and progressively
radially outwards until they terminate in a thin but smoothly rounded tip at or very
closely adjacent to the tube inner surface. It will be understood by those skilled
in the art that, because of usual manufacturing tolerances in the manufacture of the
tubes and the interrupter structures, and also because of the need to be able easily
to insert the structures into and remove them from the tubes, there may not always
be positive contact at an interruption spot between the blade member and the tube
interior wall, but the required effect will be obtained as long as the blade edge
intrudes into the boundary layer. In a typical example of a small heat exchanger e.g.
of capacity 20 litres/minute, and in which the tubes are of 1.25 cm internal diameter
the tolerance required in the manufacture of the tube and interrupter structure in
0.5 mm to 1.0 mm, which is readily realisable.
[0023] At the radially inner part of each interrupter element, i.e. where the roots of the
blades meet the core rod, there is a maximum of blade surface area relative to the
path cross-sectional area for fluid flow through the element, so that the friction
drag is at a maximum. On the other hand, at the radially outer parts of the element
blades the amount of blade material has become substantially zero, so that the friction
drag is reduced in relation to the cross sectional area. Because of these differentials
in friction and cross sectional area a change of momentum is produced in the fluid
as it passes through the element that induces the development of smooth, non turbulent
vortices producing rapid and effective mixing of the separated boundary layer and
its adjacent core layerfor increase in heat exchange efficiency. There is also highly
effective contact of the fluid with the surface of the interrupter element and with
any material such as a catalytic material thereon. The fluid in these momentum induced
vortices moves from element to element longitudinally of the structure, and the spacing
between the elements is made such that what is known as wake interference flow is
established by the coincidence between a vortex upstream of an interruption point
with a vortex downstream of a subsequent interruption point, such wake interference
flow providing the highest mixing and heat transfer efficiency with lowest required
pumping power.
[0024] Another of the results of this particular blade configuration is that the fluid flow
is predominantly in the radially outer portion ofthetube interior with increased fluid
velocities particularly at the tube inner wall surface. This type of flow has a number
of beneficial effects on the heat transfer efficiency, in that the rate of heat transfer
is fundamentally increased because of the rapid flow past the heat transfer surface,
while the boundary layer is kept thin and more easily disrupted by the shearing effect
of the high velocity fluid.
[0025] The general direction offlow of the fluid in a tube is indicated in Figure 5 by arrows
54a and it will be seen that the flow interrupter structure causes the production
of flow eddies 54a of shape and rotational frequency that, as described above, depend
upon the geometry of the structure. Wake eddies will be produced around the spots
52 of interruption downstream of the flow, while advance eddies will be produced upstream
of the flow. If the spacing of the interruption spots 52 is made such that the advance
and wake eddies of immediately successive spots coincide, then the desired wake interference
flow is obtained with its very efficient non turbulent mixing between the interrupted
boundary layers and the adjacent core layer. Aturbulentflow, which is to be avoided,
may be distinguished from a vortex or eddy in that the former is irregular and there
is no observable pattern as with a vortex. Vortices, eddies and swirls therefore do
not constitute turbulence. The conditions for maintenance of non turbulent flow with
a particular structure can be observed for example by providing suitable windows in
an experimental structure and adding visible fluids to the fluid flow if required.
[0026] The interrupter structure may readily be produced relatively inexpensively as a cast
or moulded integral element of required diameter, element spacing and element free
end length. A variety of different materials can be used, such as metals, non-metallic
materials such as plastics materials, and refractory materials such as alumina and
cements. Because of its relatively large surface area and its efficient surface contact
with the mixing flowing fluid the interruption structure is particularly suited as
a support for material with which the fluid is to be contacted, such as a catalytic
material. In other embodiments comprising reactor apparatus the interrupter structure
itself can be made of the contact and/or catalytic material, and alumina is a specific
example of such a material having this dual property.
[0027] The number of blade like members to be provided is a matter of design for each heat
exchanger. A practical minimum is three, while for small exchangers (e.g. using tubes
of 1.25 cm and less) more than ten would usually result in too great a loss of flow
capacity.
[0028] Figure 4a shows in side elevation part of a structure in which the profile of the
element is spherical; the profile is of course a circle. Other profiles can be used
and should be such as to present smoothly contoured edges to the fluid flow, so as
to reduce friction losses to a minimum and also to ensure the maintenance of non turbu-
lentflow. Figure 4b shows for example elements of an ellipsoidal profile, while Figure
4c shows elements of an egg or drop shaped profile; in the latter two profiles the
edge of largest radius faces upstream.
[0029] Special situations arise for example when the fluid is very viscous, such as a viscous
oil that is to be heated. Such a fluid is usually of low thermal conductivity and
a thermal boundary layer will be established immediately adjacent to the heat transfer
surface that is much thinner than the flow boundary layer. The interrupting structure
must be arranged to interrupt this thinner thermal . boundary layer irrespective of
the thickness of the flow boundary layer. The principle factor in the determination
of the thickness of the thermal boundary layer is the Prandtl number, which is high
when the viscosity is high and the thermal conductivity is low.
[0030] One of the principle parameters to be considered in determining whether a particular
fluid flow will be non-turbulent is the Reynolds number which is obtained by the relation:
Classically it was believed that with a Reynolds number less than about 4,000 the
flow must be non-turbulent, while if it was greater than about 6,000 it would become
turbulent. An indication that the flow will be non-turbulent is to plot a friction-factor
curve, beginning at low Reynolds numbers, say R=
100, which will show an abrupt change in slope at the onset of turbulence. The existence
of a friction-factor curve of constant slope can therefore be an indication that essentially
non-turbulent flow is occurring and with the apparatus of the invention this can be
maintained with Reynolds numbers as high as 15,000.
[0031] The evaluation of the performance of heat exchanger surfaces is a difficult subject
because of the large number of variables involved, but one method that has gained
acceptance is described in the Transactions of the Society of Mechanical Engineers,
Vol. 100, August 1978 in a paper by J. G. Soland, W. M. Mack, Jr. and W. M. Rohsenow
entitled "Performance Ranking of Plate-Fin Heat Exchanger Surfaces". This method involves
the plotting of the number of heat transfer units (NTU) per unit volume of the heat
exchanger core (V), against the pumping power (E) required to move the fluid through
the core per unit volume of the heat exchanger core (V).
[0032] Figure 7 is a plot of the ranking of surfaces in accordance with this method, comparing
surfaces provided wihh an interrupter structure of the invention with a surface constituted
by a tube of 1.2 cm diameter and a plate heat exchanger of 0.5 cm plate pitch. Thus
the vertical plot indicates the number of heat transfer units (NTU) per unit volume
of the heat exchanger core (V), while the horizontal plot indicates the pumping power
(E) required to move the fluid through the core per unit volume of the heat exchanger
core (V).
[0033] The test fluid was water and the lowest line A is for heat transfer in a plain tube
of 1.2 cm diameter, using data obtained from the above-mentioned paper of Soland,
Mack and Rohsenow. The line B is for an "APV" plate heat exchanger of 0.5 cm plate
pitch, using data obtained from the "APV Heat Transfer Handbook, 2nd Edition, published
by APV Inc. of Tonawanda, New York, U.S.A.". It will be seen that line B represents
an improvement of 28% in performance over line A. The lower line C plots the performance
of a shell and tube heat exchanger of the invention employing seven tubes of 1.25
cm diameter and equipped internally with radially bladed interrupter structures and
externally with sphere rods on the shell side with a sphere diameter of 1 cm. The
higher line D plots the maximum performance so far obtained with a heat exchanger
of the invention. It will be seen that line C represents an improvement of respectively
250% and 200% of lines A and B, while line D represents an improvement of respectively
515% and 400%.
[0034] The embodiment of Figures 1 to 3 employs a different form of interrupter structure
in the fluid path constituted by the space between the shell interior and the tube
exteriors, although the above described bladed structure can of course be used. The
different structure also consists of a core rod 54, but the longitudinally spaced
interrupter elements consist of solid spheres 56 mounted on the rod at the spacing
required to provide wake interference fluid flow. These sphere carrying rods, for
convenience called sphere rods, are disposed around the tube exteriors with these
longitudinal axes parallel to the tube axes and with their spherical surfaces in point
contact with the adjacent tube surfaces; at some locations the spheres may also touch
one another. The spheres have the same effect of point interruption of the boundary
layers and production of mixing vortices that increase the heat transfer from the
exterior tube surfaces to the fluid. It will be noted that the ends of the sphere
rod cores are free of spheres and are in end engagement with the tube sheets 16, so
that they can be located accurately longitudinally, by changing the length of the
sphere free ends the spheres of one rod can therefore be arranged to be opposite to
the spaces between the spheres on the immediately adjacent rods to ensure the maximum
fluid flow capacity in the path, and minimize the pressure drop of the fluid through
the shell. The rod ends are also made free of spheres to provide fluid flow plenum
spaces of adequate flow capacity in the shell adjacent the inlet and outlet to the
shell. The radially outer sides of the radially outermost sphere rods are surrounded
by a filler material 58 to block the non heat exchanging flow of fluid that would
otherwise take place between the inner wall of the shell and the adjacent outer parts
of the tube walls.
[0035] It will be seen that the entire heat exchanger is readily disassembled by removal
of the encircling band clamps 38 and 42 and split rings 36 and 40, when the tube sheet
assemblies can be removed and the interrupter assemblies of both types slid out from
inside and between the tubes for replacement or cleaning, as may be required. It will
be seen that this disassembly and subsequent reassembly can be effected extremely
rapidly by unskilled labour using simple tools. The resulting separate parts can easily
be cleaned with simple apparatus.
[0036] Figure 6 illustrates in cross section a reactor apparatus employing a sphere rod
interrupter structure of the invention inside each tube 25. A sphere rod structure
usually is somewhat less expensive to make than the bladed interrupter structure,
and is also somewhat more robust. A bladed structure may however be employed if the
additional surface area which it provides is advantageous. it will be noted that with
this solid spherical structure to ensure adequateflow offluid through the path the
sphere elements on the rod are of substantially smaller external diameter than the
tube internal diameter. The sphere rod core element should rest on the bottom of the
horizontal tube interior so that its spherical structure elements will each penetrate
at least at one point each the interior boundary layer of the tube and interrupt it
there. In practice the external sphere diameter should be between 50% and 80% of the
tube internal diameter. Although for convenience the elements are referred to as spheres
they also can be of ellipsoidal, egg or drop shape and an egg shaped element structure
is illustrated to the right of Figure 6. Spheres of 80% or less of tube internal diameter
permit adequate fluid flow, while spheres of 50% or more of tube internal diameter
are required for adequate performance in both boundary layer disruption and vortex
generation.
1. A fluid handling apparatus in which a fluid flows along a solid surface (20), for
example for heat exchange or reaction, in which a flow-modifying structure (44) is
placed in the fluid flow path adjacent the solid surface (20), which flow-modifying
structure (44) comprises a plurality of interrupter elements (46) spaced in the direction
of flow, each interrupter element (46) is of at least approximately spherical profile,
as seen in side elevation, and the interrupter elements touch or nearly touch the
surface (20) in such a manner that they locally establish non-turbulent interruptions
of the fluid flow at the surface (20) while establishing mixing zones in the main
body of the fluid spaced from the surface, characterised in that each interrupter
element (46) comprises a plurality of blade-like members (50) which extend radially
outwards relative to one another, whereby the boundary layer of the fluid flowing
along the surface (20) is locally interrupted by the tips of the blades at points
(52) which are spaced both laterally and longitudinally relative to the fluid flow
direction.
2. The apparatus claimed in claim 1, wherein the spacing between immediately successive
interrupter elements (46) is such as to produce wake interference flow in the fluid.
3. The apparatus claimed in claim 1 or 2 in which each blade-like member is thicker
at its root than at its tip, and tapers progressively, radially outwards from the
root to the tip.
4. The apparatus claimed in any preceding claim, wherein the structure (44) comprises
an axial core element (48) by which the interrupter elements (46) are connected to
one another and along which the interrupter elements are spaced.
5. The apparatus claimed in any of claims 1 to 4, wherein the fluid handling apparatus
comprises a fluid reactor in which the interrupter structure is coated with a material
exhibiting reactive and/or catalytic properties towards the fluid.
6. The apparatus claimed in any one of claims 1 to 4, which is a heat exchange apparatus
in which the interrupter elements (46) are disposed adjacent the surface of a wall
(20) through which heat exchange takes place.
7. The apparatus claimed in claim 6 wherein the heat exchange apparatus is of the
shell and tube type wherein each tube has therein a said interrupter structure.
8. The apparatus claimed in claim 7 wherein each tube (20) has at least one further
interrupter structure (54, 56) in contact with its external surface through which
surface heat exchange takes place to fluid in the shell (10).
9. The apparatus claimed in claim 8 wherein each external interrupter structure comprises
an elongated axial core element (54) extending in the direction of fluid flow of the
fluid, and
a plurality of spaced spherical interrupter elements (56) extending along the said
core element.
10. The apparatus claimed in claim 9, wherein the axial core element (54) of the external
interrupter structure is free of interrupter elements (56) at its ends.
11. The apparatus as claimed in any of claims 8 to 10, wherein the further interrupter
structure (54, 56) in such a manner as to produce wake interference flow in the fluid,
and the spherical elements (56) locally interrupt the boundary layer of the fluid
flow at the surface (20).
12. The apparatus claimed in claim 11, wherein the further interrupter structure is
disposed within a tube and each spherical element (56) has an external diameter from
50% to 80% of the internal diameter of the tube.
13. The apparatus claimed in claim 11 or 12, which comprises a fluid reactor in which
the further interrupter structure is coated with a material exhibiting reactive and/or
catalytic properties toward the fluid.
14. The apparatus claimed in claim 11, 12, or 13 wherein the further interrupter structure
core is free of spherical elements at its ends.
15. The apparatus claimed in any of claims 7 to 14 wherein the interrupter structure
(44) inside the tube (20) is free of interrupter elements at its ends.
1. Fluidabehandlungsvorrichtung in welcher ein Fluid entlang einer festen Oberfläche
(20) strömt, z.B. zum Zwecke des Wärmetausches oder einer Reaktion, wobei eine die
Strömung beeinflussende Anordnung (44) im Strömungsweg des Fluids angrenzend zur festen
Öberfläche (20) vorgesehen ist, welche Anordnung (44) eine Mehrzahl von in Strömungsrichtung
beabstandeten Brechungselementen (46) umfaßt, von denen jedes in Seitenansicht zumindest
annähernd kugelförmiges Profil aufweist, und wobei die Brechungselemente die Oberfläche
(20) auf solche Art berühren oder zumindest annähernd berühren, daß sie lokale, nicht-turbulente
Unterbrechungen der Fluidströmung an der Oberfläche (20) bewirken, während im von
der Oberfläche beabstandeten Hauptteil des Fluids Mischzonen gebildet werden, dadurch
gekennzeichnet, daß jedes Brechungselement (46) eine Mehrzahl von klingenartigen Einheiten
(50) umfaßt, die relativ zueinander radial auswärts verlaufen, wodurch die Grenzschichte
des entlang der Oberfläche (20) fließenden Fluids lokal durch die Spitzen der Klingen
an Punkten (52) unterbrochen wird, welche sowohl senkrecht zur als auch in Richtung
der Fluidströmung beabstandet sind.
2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß der Abstand zwischen unmittelbar
aufeinanderfolgenden Brechungselementen (46) so ist, daß eine Wirbelinterferenzströmung
im Fluid erzeugt wird.
3. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß jede klingenartige
Einheit an ihrer Wurzel dicker als an ihrer Spitze ist und sich progressiv radial
auswärts von der Wurzel zur Spitze verjüngt.
4. Vorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß
die Anordnung (44) ein axiales Kernelement (48) umfaßt, mittels welchem die Brechungselemente
(46) untereinander verbunden sind und entlang von welchem die Brechungselemente beabstandet
sind.
5. Vorrichtung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Fluidebehandlungsvorrichtung
einen Fluidreaktor umfaßt, in dem die Brechungsstruktur mit einem Material beschichtet
ist, welches reaktive und/oder katalytische Eigenschaften gegenüber dem Fluid aufweist.
6. Vorrichtung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß sie als
Wärmetauschvorrichtung ausgebildet ist, in der die Brechungselemente angrenzend an
die Oberfläche einer Wand (20) durch welche der Wärmetausch stattfindet angeordnet
sind.
7. Vorrichtung nach Anspruch 6, dadurch gekennzeichnet, daß die Wärmetauschvorrichtung
ein Röhrenwärmetauscher ist, wobei jedes Rohr eine Brechungsstruktur enthält.
8. Vorrichtung nach Anspruch 7, dadurch gekennzeichnet, daß jedes Rohr (20) zumindest
eine weitere Brechungsstruktur (54, 56) in Kontakt mit seiner äußeren Oberfläche aufweist,
durch welche Oberfläche der Wärmetausch mit dem Fluid im Mantel (10) erfolgt.
9. Vorrichtung nach Anspruch 8, dadurch gekennzeichnet, daß jede äußere Brechungsstruktur
ein verlängertes axiales Kernelement (54), welches sich in die Strömungsrichtung des
Fluids erstreckt, sowie eine Mehrzahl von beabstandeten kugelförmigen Brechungselementen
(56), die sich entlang dieses Kernelementes erstrecken, umfaßt.
10. Vorrichtung nach Anspruch 9, dadurch gekennzeichnet, daß das axiale Kernelement
(54) der äußeren Brechungsstruktur an seinen Enden frei von Brechungselementen (56)
ist.
11. Vorrichtung nach einem der Ansprüche 8 bis 10, dadurch gekennzeichnet, daß die
weitere Brechungsstruktur (54, 56) so angeordnet ist, daß eine Wirbelinterferenzströmung
im Fluid erzeugt wird, und daß die kugelförmigen Elemente (56) die Grenzschicht der
Fluidströmung an der Oberfläche (20) lokal unterbrechen.
12. Vorrichtung nach Anspruch 11, dadurch gekennzeichnet, daß die weitere Brechungsstruktur
innerhalb eines Rohres angeordnet ist, wobei jedes kugelförmige Element (56) einen
äußeren Durchmesser im Bereich von 50 bis 80% des Innendurchmessers dieses Rohres
aufweist.
13. Vorrichtung nach Anspruch 11 oder 12, dadurch gekennzeichnet, daß sie einen Fluidreaktor
umfaßt, in welchem die weitere Brechungsstruktur mit einem Material beschichtet ist,
welches reaktive und/oder katalytische Eigenschaften gegenüber dem Fluid aufweist.
14. Vorrichtung nach Anspruch 11, 12 oder 13, dadurch gekennzeichnet, daß der Kern
der weiteren Brechungsstruktur an seinen Enden frei von kugelförmigen Elementen ist.
15. Vorrichtung nach einem der Ansprüche 7 bis 14, dadurch gekennzeichnet, daß die
Brechungsstruktur (44) im Inneren des Rohres (20) an den Enden frei von Brechungselementen
ist.
1. Appareil de traitement d'un fluide, dans lequel un fluide circule le long d'une
surface solide (20), par exemple pour un échange de chaleur ou une réaction, et dans
lequel une structure (44) de modification de l'écoulement est disposée dans le trajet
d'écoulement du fluide au voisinage de la surface solide (20), laquelle structure
(44) de modification de l'écoulement comporte une pluralité d'éléments d'interruption
(46) espacés dans la direction d'écoulement, chaque élément d'interruption (46) possédant
un profil au moins approximativement sphérique, lorsqu'on le regarde selon une vue
en élévation latérale, et les éléments d'interruption sont en contact ou presque en
contact avec la surface (20) de telle sorte qu'ils créent localement des interruptions
non turbulentes de l'écoulement du fluide sur la surface (20), tout en établissant
des zones de mélange dans le volume principal du fluide écarté de la surface, caractérisé
en ce que chaque élément d'interruption (46) comporte une pluralité d'organes en forme
de pales (50) qui s'étendent radialement vers l'extérieur les uns par rapport aux
autres, ce qui a pour effet que la couche limite du fluide s'écoulant le long de la
surface (20) est interrompue localement par les pointes des pales au niveau de points
(52) qui sont espacés à la fois latéralement et longitudinalement par rapport à la
direction d'écoulement du fluide.
2. Appareil selon la revendication 1, dans lequel l'espacement entre des éléments
d'interruption (46) se succédant directement est tel qu'ils produisent un écoulement
perturbateur en forme de remous dans le fluide.
3. Appareil selon la revendication 1 ou 2, dans lequel chaque organe en forme de pale
est plus épais au niveau de sa base qu'au niveau de sa pointe, et s'amincit progressivement
radialement vers l'extérieur depuis la base en direction de la pointe.
4. Appareil selon l'une quelconque des revendications précédentes, dans lequel la
structure (44) comporte un élément central axial (48), au moyen duquel les éléments
d'interruption (46) sont raccordés entre eux, et le long duquel les éléments d'interruption
sont espacés.
5. Appareil selon l'une quelconque des revendications 1 à 4, dans lequel l'appareil
de traitement de fluide comporte une enceinte réactionnelle pour le fluide, dans laquelle
la structure d'interruption est recouverte par un matériau présentant des propriétés
réactives et/ou catalytiques vis-à-vis du fluide.
6. Appareil selon l'une quelconque des revendications 1 à 4, qui est un appareil d'échange
de chaleur, dans lequel les éléments d'interruption (46) sont disposés de manière
à être adjacents à la surface d'une paroi (20) à travers laquelle s'effectue l'échange
de chaleur.
7. Appareil selon la revendication 6, dans lequel l'appareil d'échange de chaleur
est du type à coque et tubes, dans lequel chaque tube contient en lui une structure
d'interruption.
8. Appareil selon la revendication 7, dans lequel chaque tube (20) possède au moins
une structure supplémentaire d'interruption (54, 56) en contact avec sa surface extérieure,
à travers laquelle l'échange de chaleur s'effectue avec le fluide situé dans la coque
(10).
9. Appareil selon la revendication 8, dans lequel chaque structure extérieure d'interruption
comporte un élément central axial (54) qui s'étend dans la direction de l'écoulement
du fluide, et une pluralité d'éléments sphériques d'interruption espacés (56) qui
s'étendent le long dudit élément central.
10. Appareil selon la revendication 9, dans lequel ledit élément central axial (54)
de la structure extérieure d'interruption est exempt d'éléments d'interruption (56)
au niveau de ses extrémités.
11. Appareil selon l'une quelconque des revendications 8 à 10, dans lequel la structure
supplémentaire d'interruption (54, 56) est disposée de manière à produire un écoulement
perturbateur produisant des remous dans le fluide, et les éléments sphériques (56)
interrompent localement la couche limite de l'écoulement du fluide au niveau de la
surface (20).
12. Appareil selon la revendication 11, dans lequel la structure supplémentaire d'interruption
est disposée à l'intérieur d'un tube et chaque élément sphérique (56) présente un
diamètre extérieur compris entre 50% et 80% du diamètre intérieur du tube.
13. Appareil selon la revendication 11 ou 12, qui comporte une enceinte réactionnelle
pour le fluide, dans laquelle la structure supplémentaire d'interruption est recouverte
par un matériau présentant des propriétés réactives et/ou catalytiques vis-à-vis du
fluide.
14. Appareil selon la revendication 11, 12 ou 13, dans lequel le coeur de la structure
supplémentaire d'interruption est exempt d'éléments sphériques au niveau de ses extrémités.
15. Appareil selon l'une quelconque des revendications 7 à 14, dans lequel la structure
d'interruption (44) située à l'intérieur du tube (20) est exempte d'éléments d'interruption
au niveau de ses extrémités.