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Патент USA US3053522

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SePt- 11, 1962
Filed April 5, 1959
United States Patent O??ce
exchanger unit 10 is intended to be placed in a chemical
vessel (not shown) which also contains a stirring appara
tus. It is supposed that the stirring apparatus will lie
within the circle of the units 14 and the entire vessel will
Paul Soudan, Aix-en-Provence, and Henri Mercier, Ga -
danne, France, assignors to Pechiney, C0mpagnie de
Produits Chimiques et Electrometallurgiques, Paris,
be ?lled with a chemical which may be a viscous liquid
or a thick suspension of solids in a liquid. Depending
upon the chemical process, it may be desirable either to
heat or cool the liquid in the vessel for which purpose
France, a corporation of France
Filed Apr. 3, 1959, Ser. No. 803,887
Claims priority, application France Apr. 9, 1958
6 Claims. (Cl. 257-154)
steam or hot water may be introduced into the heat ex
10 changer or cooling liquid. In the case of cooling, the
coolant enters the unit through the inlet tube 18 and
?lls the upper main header 17. It passes down through
the individual connecting tubes 12 into the upper sec
This invention relates to a heat exchanger and more
particularly to a heat exchanger which is especially suit
able for applications in industries in which liquids must
be cooled or heated while being stirred.
Heat exchange is a problem which is common to al
most all industries, but presents particular di?iculties
in chemical engineering applications where viscous liquids
ondary headers 15 which distribute it to the individual.
tubes 13‘. The principal heat exchange actually takes
place through the tubes 13 and the surrounding liquid
in the vessel. The cooling liquid passes through the
tubes from the upper end to the lower end and is col
or suspensions of solids in liquids are used and in which
these materials must be heated or cooled while being
Patented Sept. 11, 1962
lected in the lower secondary header 16 from which it
passes through the connecting tube 11 into the lower
main header 19. The coolant fluid then passes through
the outlet tube 20' and is returned to its source. The pro
cedure is similar if the ?uid is a heating ?uid. The stir
Dif?culty is especially experienced when the
materials which must be treated tend to encrust the
apparatus. These and other dit?culties of the prior art
devices have been obviated in a novel manner by the
ring apparatus will cause a ?ow of the liquid in the ves~
present invention.
It is, therefore, an outstanding object of the invention 25 sel around the tubes 13‘ and produce heat exchange be
to provide a heat exchanger Which is particularly effec
tive and ef?cient in operation.
Another object of this invention is the provision of a
heat exchanger for use in heating or cooling viscous
liquids or suspensions of solids in liquids while they are 30
being stirred, the heat exchanger being capable of use
even when the materials tend to encrust the apparatus.
tend around the tubes.
A further object of the present invention is the provi
In FIG. 3 a connecting tube 24- leads into an upper
secondary header 25 which is connected to tubes 26.
The tubes are connected to the header 25 in pairs, each
pair lying in a plane Which is radial to the header 25; in
other words, the centerlines of each pair of tubes lie in
and covered by the claims appended hereto.
The character of the invention, however, may be best
understood by reference to certain of its structural forms
a plane which passes through the axis of an imaginary
cylinder joining the centerlines of the upper and lower
secondary headers. One of each pair is connected to
as illustrated by the accompanying drawings in which:
FIG. 1 is a perspective view of the apparatus embody
FIG. 2 is a modi?cation of the apparatus;
FIG. 3 is a further modi?cation of the apparatus; and
FIG. 4 is a still further modi?cation of the apparatus
of the invention.
Referring ?rst to FIG. 1, wherein are best shown the
general features of the invention, the heat exchanger,
These spiral corrugations in
crease the heat exchange surface of the tubes and they,
therefore, promote the ?ow of heat from a material ex
terior of the tubes to the ?uid in the interior of the tubes.
sion of a heat exchanger which considerably increases
the overall coef?cient of heat transmission and yet which
is easy to construct and maintain.
With these and other objects in view, as will be appar
ent to those skilled in the art, the invention resides in
the combination of parts set forth in the speci?cation
ing the principles of the present invention;
tween the coolant ?uid and the chemical ?uid in the
FIGS. 2, 3, and 4 show variations of the shapes of the
tubes in the units 14. For instance, in FIG. 2 a connect
ing tube 2.1 enters a secondary header 22 which is asso
ciated with tubes 23. As is evident in the drawings, the
tubes 23 are formed with spiral corrugations which ex
the header 25 at the inner surface and the other of the
pairs is connected to the header at the outer surface;
the tubes, therefore, form concentric, generally cylindri
cal sets of tubes.
In FIG. 4 a connecting tube 27 is attached to a sec
ondary header 28 to which are attached tubes 29. Each
tube consists of a series of generally radial sections alter
indicated generally by the reference numeral 10‘, is shown
nated with angular sections to form a zig-zag conforma
lower main circular header 19 arranged in spaced, paral
It can be seen, then, that the heat exchanger of the
lel relationship. An entrance tube 18 enters the upper 55 present invention contains an improvement whose pur
main header 17 while an outlet tube 20‘ leaves the lower
pose is mainly in considerably increasing the overall
main header. Arranged between the main headers are
coef?cient of heat transfer. At the same time the con
a series of sets 14- each of which consists of an upper
struction and maintenance is rendered much easier. An
as consisting of an upper circular main header 17 and a
circular secondary header 15 and a lower circular sec
other advantage of the new apparatus resides in an im
ondary header 16 joined by parallel tubes 13. A con
necting tube 11 joins the lower secondary header 16 to
the lower main header 19‘, while a connecting tube 12
joins the upper secondary header 15 to the upper main
portant reduction of the incrustation of heat exchange ele
ments. Also, the heat exchanger, according to the in
contraction lengthwise of the tubes 13-.
diameter of tubes used in presently known exchangers.
When the ratio of diameter to the length of the tube is
made low enough, the interplay of thermal expansion
and contraction produces a vibration which is favorable
vention, leads to a very large increase of exchange sur
face in comparison with conventional apparatus of a
header 17, the connecting tube 12 being in the form of a
same capacity. It should be noted that the ratio of the
spiral which is capable of considerable expansion and 65 diameter of each tube of the sets is much lower than the
It should be
noted that the units 14 are arranged so that they are gen
erally tangential to the outer surface of an imaginary
cylinder joining the centerlines of the annuli which de?ne
the main headers 17 and 19.
70 for automatically removing incrustations from the heat
The operation of the apparatus will now be readily
ing surfaces. It can be understood that the units lie well
understood in view of the above discussion. The heat
outwardly against the walls of the vessel where they are
subjected to the greatest velocity of ?ow of the material
being stirred in the vessel so that the heat exchange is
greatest because of this greater velocity.
In one application of the invention, it was used for the
alkaline digestion of bauxite under pressure wherein a
suspension of powdered bauxite in alkaline liquor was
headers a thin, ?exible tube joining each upper secondary
header to the upper main header, a thin, ?exible tube
joining each lower secondary header to the lower main
header, the ?exible tubes ‘being the sole support for each
2. A heat exchanger as recited in claim 1 wherein each
set is related to the main headers so that most of its
heated within an autoclave provided with a stirrer. In
tubes lie outside of an imaginary cylinder joining the
substituting the present invention for the conventional
centerlines of the main headers.
series of peripheral tubes, an increase of 50% of the 10
3. A heat exchanger, comprising an upper and a lower
heating surface was obtained. Similarly, when conven
main annular header, the headers being arranged in
tional coils were replaced by the construction of the in
spaced, parallel relationship, a series of sets joining the
vention the total amount of heat transfer was increased
headers, each set comprising an upper and a lower an
by 100% (doubled). The autoclave had a diameter of
nular secondary header considerably smaller in major
2.60 meters and was 8.5 meters in height. Fifteen sets
were used each having twelve uniform tubes placed as
shown in FIG. 1. Each tube was 55 millimeters in ex
ternal diameter and was 6.4 meters long. This provided
diameter than the said main headers, the headers in each
set being arranged in spaced parallel relationship, a series
of thin, ?exible tubes joining the secondary headers, an
a heating surface within the autoclave of 200 square
meters. A conventional heat exchanger would have only
130 square meters using 28 tubes of 200 millimeters di
amter and 7.4 meters in height. The liquid in the auto~
ing each upper secondary header to the upper main head~
er, a thin, ?exible outlet tube joining the lower second
ary header to the lower main header, each set being re
expansible thin, ?exible helically—shaped inlet tube j0in~
lated to the main headers 50 that most of its tubes lie
clave had a density of 1.4 grams per centimeter and vis~
outside of an imaginary cylinder joining the centerlines
cosity was 2 centipoises at 100° C. When the suspended
of the main headers, the ?exible inlet tube and the flex
liquor was heated from 200° C. to 230° C. with satu 25 ible outlet tube constituting the sole support for each set.
rated steam at 235° C., an overall heat transfer coe?icient
was obtained of 2,000 calories per square meter per hour
per degree of centigrade, instead of 800‘ or 900 calories
per square meter per hour per degree of Centigrade ob
4. A heat exchanger as recited in claim 3 wherein each
tube is formed with a spiral corrugation.
5. A heat exchanger as recited in claim 3 wherein the
tubes are attached to the secondary headers in pairs, each
tained with a conventional heat exchanger working in the 30 pair being arranged in a radial plane, one being con
same conditions.
nected to the inner surface of the headers while the other
It is obvious that minor changes may be made in the
is connected to the outer surface of the headers.
form and construction of the invention without depart
6. A heat exchanger as recited in claim 3 wherein each
ing from the material spirit thereof. It is not, however,
tube consists of radial portions alternated with angular
desired to con?ne the invention to the exact form herein 35 portions to obtain a zig-zag conformation.
shown and described, but it is desired to include all such
as properly come within the scope claimed.
References Cited in the ?le of this patent
The invention having been thus described, what is
claimed as new and desired to secure by Letters Patent is:
1. A heat exchanger, comprising an upper and a lower 40
main circular header, the headers being arranged in
spaced, parallel relationship, a series of sets joining the
headers, each set comprising an upper and a lower circu~
lar secondary header considerably smaller in diameter
than the said main headers, the headers in each set being 45
arranged in spaced parallel relationship, and a series of
thin, helically-shaped ?exible tubes joining the secondary
Power ______________ .._ June 4,
Earle _______________ __ July 1,
Lucke ______________ __ Oct. 25,
Lucke et al. _________ __ Oct. 25,
Turner ______________ __ May 2,
Borg _______________ __ Dec. 16,
Brown ______________ __ June 2,
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