Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates in general to heat exchangers and in
particular to an apparatus for heating liquid by use of either a liquid
or a vapour.
Liquids have been heated by fluids such as steam or other hot
liquids in various manners. It is known that heat transfer coefficients
and the efficiency of the heat exchanger improve with the velocity of the
fluids. One type of heat exchanger employing high flow rates uses con-
centric pipes. The cold liquid is forced through the inner pipe while steam
is forced through the annular space. Heat is transferred from the steam
through the walls of the inner pipe. ~owever the heat transferred to the
outer pipe walls is lost, since the liquid to be cooled is located only in
the interior pipe.
In United States Patent ~03,123, a steam water heater is disclosed
that uses a bundle of concentric tubes in a tank. Cold water flows up
through the annular passage of some of the tube pairs and down the annular
passages of others. Some of the steam flows up the inner tubes, while the
remainder passes exterior of the outer tubes and out the top of the tank.
The velocity of flow is reduced in the resultingly large steam flow areas.
In additionj a portion of the s~eam flows over the cold water intake at a
point where thermal stresses and expansion cannot be easily alleviated.
It is accordingly a general object of this invention to provide
an improved apparatus for exchanging heat between two fluids.
According to one aspect of the invention there is provided
an apparatus for exchanging heat between two fluids comprising: at least one ;-~
inner tube spaced concentrically in an outer tube, defining an inner passage
and an annular passage; first manifold means located at the first end of the -~
apparatus for directing all of the incoming first fluid to the inlet of the
inner passage; the first manifold means comprising a first partition at the
first end of the apparatus having an aperture for sealingly receiving the
inlet of the im1er tube; and a first housing having a closed end and sealingly
secured to the first partition, with an inlet on its closed end for receiving
first fluid and directing all of it to the inlet of the inner tube; second
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manifold means located at the first end of the apparatus for directing all
of the incoming second fluid to the inlet of the annular passage; the second
manifold means comprising a second partition spaced from the first partition
and having an aperture for sealingly receiving the inlet of the outer tube;
and a second housing sealingly enclosing the space between the first and
second partitions and having an inlet for receiving second fluid and direct-
ing it to the inlet of the outer tube; third manifold means at the second
end of the apparatus for directing discharged second fluid out o-f the
apparatus, including a discharge conduit extending from the second end of
the apparatus back to the first end of the apparatus; the third manifold
means comprising a third partition at the second end of the apparatus~
having an aperture for sealingly receiving the outlet of the inner tube;
a fourth partition spaced from the third partition and having an aperture
for sealingly receiving the outlet of the outer tube and an aperture for
sealingly receiving the inlet of the discharge conduit, the discharge
conduit extending through the second partition and discharging second fluid
exterior of the housing; and a third housing sealingly enclosing the space
between the third and fourth partitions to direct second fluid from the out-
let of the outer tube to the inlet of the discharge tube; and a jacket having
a closed end enclosing substantially the length of the outer tube and having
an outlet spaced close to the inlet of the annular passage, but separated
from it, so as to cause the discharged first fluid to flow over the outer
tube, exchanging heat through the walls of the inner and ou~er tubes.
According to another aspect of the invention there is provided
an apparatus for exchanging heat between two fluids flowing at different
temperatures, comprising: at least two tube-pairs spaced apart and parallel
with each other, each tube-pair having an inner tube spaced concentrically
in an outer tube, defining an inner passage and an annular passage; first
manifold means at the first end of the apparatus for directing all of the
incoming first fluid to the inner passage of each tube-pair; second manifold
means at the first end of the apparatus for directing all of the incoming
second fluid to the annular passage of one of the tube-pairs; third manifold
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means for placing the ends of the annular passage at the second end of the
apparatus in communication with each other, causing incoming second fluid
to flow out of the annular passage of one tube-pair into the annular passage
of the other tube-pair, the third manifold means further separating the
incoming second fluid from the discharging second fluid at the first end of
the apparatus; and a jacket having a closed end on the second end of the appa-
ratus enclosing a substantial portion of the tube-pairs and having an outlet
spaced a selected distance from the second end so as to cause discharged
first fluid flow over the outer tubes, further transferring heat; the first
manifold means comprising: a first partition at the first end of the
apparatus having an aperture for sealingly receiving the inner tubes~ and a
cup-shaped first housing sealingly secured to the first partition with an
inlet for receiving first fluid and directing all of it to the inner passages
of the inner tubes; the second manifold means comprising: a second partition
spaced from and parallel to the first partition and having an aperture for
sealingly receiving the first end of the annular passage of one tube-pair;
and a second housing sealingly enclosing the space between th0 first and
second parti.tions with an inlet for receiving second fluid and directing it
to the annular passage; the third manifold means comprising: a third
partition at the second end of the apparatus having an aperture for sealingly
receiving the outlet of the inner tube; a fourth partition spaced from and .
parallel wi.th the third partition and having an aperture for sealingly
receiving the second end of the outer tube of each tube-pair; a third
housing sealingly enclosing the space between the third and fourth partitions ::
to direct discharged second fluid from the annular passage of one tube-pair
to the annular passage of the other tube-pair, the outer tube of the
tube-pair that receives the discharged second fluid being sealingly received
in an aperture in the second partition; and a baffle extending between the
first and second partitions transverse to them to divide the space enclosed
by the second housing into intake and discharge chambers, the second housing
having an outlet in the discharge chamber for discharging second fluid.
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According to a further aspect of the invention there is provided
an apparatus for heating a liquid with a fluid comprising: two tube-pairs
spaced parallel with each other and mounted in the wall of a storage tank
with a substantial portion of their lengths located in the tank, each tube-
pair having a single inner tube carried concentrically within a single
outer tube; the inner tube in each tube-pair being connected exterior of the
tank to the source of the liquid, and being open at their interior ends for
discharging the liquid; the outer tube in one tube-pair being connected
exterior of the tank to the source of the heating fluid, the interior ends
of the outer tube of each tube-pair being connected together to return the
heating fluid through the outer tube of the other tube-pair, this outer
tube being connected exterior of the tank to a return for the heating fluid; :
and a jacket extending from the interior wall of the tank and enclosing the
tube-pairs, the jacket having a closed end surrounding the interior ends of
the tube-pairs but separated from the interior ends for receiving the
discharge of liquid from the inner tubes and reversing the direction of flow,
and an outlet located substantially at the wall of the tank so as to direct
the discharged liquid over the outer tubes from the interior ends toward the
wall, then through the outlet and into -the tank, further exchanging heat with
the heating fluid in the outer tubes.
According to yet another aspect of the invention there is provided
an apparatus for e~changing heat between two fluids, comprising: two tube- ~ :
pairs spaced parallel with each other, each tube-pair having a single outer
tube and a single inner tube carried concentrically in the outer tube; each
inner and outer tube having a first end and a second end; first manifold
means for directing all of the incoming first fluid to the first end of each
inner tube; the second end of each inner tube being open for discharging
first fluid; a second manifold means for directing all of the incoming
second fluid to the first end of one of the outer tubes so as to flow
through the outer tube from the first end to the second end; ~he first
end of the outer tube in the other tube-pair being an outlet for discharging
second fluid; third manifold means colmecting the second ends of the ou~er
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tubes together for directing the second fluid from one outer tube to the other
outer tube to proceed to the outlet at the first end; a jacket enclosing a
substantial part of the tube-pairs, the jacket having a closed end surround-
ing the second ends of the tube-pairs for receiving the discharge of first
fluid from the second ends of the ;nner tubes, the jacket having an outlet
that is spaced from the second ends of the inner tubes a substantial distance
for causing first fluid discharged from the inner tubes to flow back over the
outer tubes toward the first ends, then out the outlet, further exchanging
heat with the second fluid flowing through the outer tubes.
According to a still further aspect of the invention there is pro- '
vided an apparatus for exchanging heat between two fluids, comprising: two :
tube-pairs spaced parallel with each other, each tube-pair having a single
outer tube and a single inner tube carried concentrically in the outer tube;
each inner and outer tube having a first end and a second end; first manifold
means for directing all of the incoming first fluid to the first end of each
inner tube; the second end of each inner tube being open for discharging
first fluid; second manifold means for directing all of the incoming second
fluid to the first end of one of the outer tubes so as to flow through the ~;-
outer tube from the first end to the second end; the first end of the outer
tube in the other tube-pair being an outlet for discharging second fluid;
third manifold means connecting the second ends of the outer tubes together -~
for directing the second fluid through the outer tube of the other tube-pair
from the second end back to the first end and the outlet; a jacket enclosing
a substantial part of the tube-pairs, the jacket having a closed end surround-
ing the second ends of the tube-pairs for receiving the discharge of first
fluid from the second ends of the inner tubes, the jacket having an outlet
means at the first end of the jacket for forcing all of the discharged first
fluid to reverse its direction of flow and flow back over the outer tubes
from the second ends toward the first ends and to the outlet means, further
3Q exchanging heat with the second fluid flowing through the outer tubes; the
third manifold means being free of attachment to the jacket to allow thermal
expansion and contracting of the tube-pairs.
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In the acco~panying drawings:-
Figure 1 is a perspective view, partially in sectionJ of a heatexchanger constructed in accordance with the teachings of this invention.
Figure 2 is a cross sectional view taken along the longitudinal
axis of the heat exchanger of Figure 1.
Figure 3 is a cross sectional view taken along the lines III-III
of Figure 2.
Figure 4 is a perspective view, partially In section, of an
alternate embodiment of a heat exchanger constructed in accordance with
the teachings of this invention.
Figure 5 is a perspective fragmentary view, partially in section,
of another alternate embodiment of a heat exchanger constructed in
accordance with the teachings of this invention.
Referring to Figures 1 through 3, a heat exchanger 11 is shown.
The heat exchanger 11 has a plurality of concentric tubes or tube-pairs 13
spaced in a bundle. Referring to Figure 2, each tube-pair comprises an
outer tube 15 within which an inner tube 17 is carried, defining an inner
passage 19 and an annular passage 21.
These tube-pairs 13 are carried in a bundle by four partitions or
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tube sheets. The first partition 23 is located on the first end and
comprises a circular plate with apertures for sealingly receiving the
inner tubes 170 The second partition 25 is spaced from the first partition
23 and comprises a circular plate with apertures for sealingly receiving
the outer tubes 15, which terminate at this plate. The third partition 27
is identical to the second partition 25, comprising a plate with apertures
for receiving the outer tubes 15, whose second ends terminate at partition
27. The fourth partition 29 is spaced substantially at the second end
of the heat e~changer and, similar to the first partition 23, has ~pertures
for sealingly receiving inner tubas 17~ Consequently the inner tubes 17
extend from the first to the fourth partitions, while the outer tubes 15
extend from the second to the third partitions. As shown in Figure 3,
one bottom tube 33 does not contain an inner tube, to facilitate flow of
condensate if steam is used as the heating medium.
The first partition 23 and second partition 25 are sealingly
enclosed in a cup-sh~ped housing 31, with the mouth of the housing at the
second partition 25 and the closed end 35 of the housing spaced away from
the first partition 23 a short distance. An inlet 37 is located in the
center of the closed end 35 of housing 31 for receiving incoming fluid,
normally water to be heated. Consequently the closed end 35, inlet 37, and
partition 23 ser~e as first manifold means for directing all of the incoming
first fluid to the inner passages 19.
A baffle 39 extends between the first and second partitions 23,
25 perpendicular to them and parallel with the tube-pairs 13. Baffle
39 is a solid plate sealingly secured to the first and second partitions
and located approximately midway in the bundle. Baffle 39 divides the
space enclosed by housing 31 into two separate chambers, designated as
intake chamber 41 and discharge chamber 43. An inlet 45 is located in
housing 31 on the side in communication with intake chamber 41. Inlet ~5
is connected to the source of the second fluid, thus serves with intake
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chamber 41 as second manifold means for directing all of the second fluid
to the annular passages 21.
kn outlet 47 is located in housing 31 in communication with the
discharge chamber 430 Outlet 47 is connected to the return or downstream
side of the second fluid source~ A cylindrical housing 49 sealingly en-
closes the space between the third and fourth partitions 27, 29~ defining
a reversing chamber 50, which in combination with the discharge chamber
QC ~ C ~ J~IS
S ~43, outlet 47 and ~e~-e~n~e~ annular passages 21, serve as third
manifold means for directing second fluid out of the heat exchanger 11.
~ cylindrical housing or jacket 51 has a closed end 53 at the
second end of the heat exchanger 11, and axtends the length of the
concentric tubes 13, terminating at the second partition 25~ A reversing
chamber 52 is defined by the space between closed end 53 and the fourth
partition 29~ The only outlet in jacket 51 is outlet 55, located
approximately at the first end of the concentric tubes 13, near partition
25. There is a clearance between housing 49 and jacket 51, causing the
outer tubes 15 to be immersed in the first Pluid of the inner passage
19 as the fluid flows toward outlet 55. Baffles could be spaced between
the jacket 51 and the concentric tubes 13 to incre2ss the velocity in this
area by causing the first fluid to flow out in an "S" pattern~
In the operation of the heat exchanger of Figures 1 through 3,
a liquid may be used to heat a liquid, or a vapor such as steam may be used
for heating the liquid. Preferably the liquid to be heated enters inlet
37, and as shown by a solid-line arrows 57 of Figures2, passes from the
- first manifold to all of the inner passages 1~. This liquid is discharged
at the second end and reverses its direction of flow in reversing chamber
52. It then passes through the space between jacket 51 and the tube bundle,
then out outlet 55, immersing substantially the entire length of the outer
tubes 15 in the liquid~
Steam enters through inlet 45 into intake chamber 41, then passes
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into the annular passages 21 that are in communication with the intake
chamber 41, as shown by the dotted-line arrows 59 of Figure 2. Heat from
the steam is transferred to the water across the walls of the inner tubes
17 and across the walls of the outer 'tubes 15. ~hen the steam reaches the-
~reversing chamber 50, the direction of flow is reversed, returning the
steam in the outer tubes 15 that terminate at the discharge chamber 43.
Steam flows through these passages, exchanging heat with water in the inner
passages 19 and on the exterior of the outer tubes 15. Condensate Mows
thrcugh tube 33 to discharge chamber 43. The remaining steam and condensate
are discharged through outlet 47.
The tubes are allowed to expand and contract due to thermal
changes, since the third and fourth partitions are not attached to jacket
51. me first and second partitions 23, 25 are attached to housing 31,
but the inner tubes 17 merely pass through the second partition 25 and are
not connected to it so as to restrain expansion.
A heat exchanger constructed as shown in Figure 1 was tested,
resulting in an increase of water temperature from 60 F to 100 F with steam
as the heating fluid. Thirty eight'gallons per minute of water was flowing
at six feet per second in inner passages 19 and the steam pressure was fif-
teen pounds gauge pressure per square inch at an altitude of 600 fee~ abovesea level. Thirteen tube-pairs 13 were used with,l/2 inch O.D. inner tubes
17 and 3/4 inch O.D. outer tubes 15. The length of the heat exchanger was
35,inches~ and,the diameter of jacket 51 was four inches~, The,clearance
between the housing 49 and the jacket 51,was 1~4 i,nch,,and ,segmental ,
baffles were placed in the spaces between the concentric tubes and the
jacket at four inch intervals.
The apparatus disclosed will also,~unction if the passages for,
the heating fluid and the liquid to,be heated ar,e interchanged. The hot-ter
or first fluid can enter through inlet 37 into the inner passages 19, and
the liquid to be heated or second fluid can pass through the annular
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passages 21. Also the directions of flow of one or both fluids can be
re~ersed. The first fluid can enter outlet 55 of the jacket, flow over
the outer tubes 15, reverse in reversing chamber 52 then pass thr~ough
the inner passages 19 from the second end to the first end~ In that case
the first manifold means for directing incoming first fluid to the inner
passages 19 would comprise outlet 55, partition 29, and jacket 51. The
second fluid could also flow in reverse. If so, the second manifold means
for directing incoming second fluid into the annular passages would include
discharge chamber 43 and outlet 47~ ~owever, if st,eam is used as the
second fluid7 an outlet on the bottom for condensate should be provided,
and the steam should preferably enter from an upper outlet. If the
second fluid flow is reversed~ the third manifold means for directing second
fluid out of the heat exchanger would include reversing chamber 50, the
interconnecting annular passages 21 with the intake chamber 41, and outlet
45.
Figures ~ and S disclose alternate embodiments. The embodiment
of Fig~lre 5 is designed particularly for heating a liquid by steam. A
single discharge conduit 61 extends from the third partition ¦not shown)
through the second partition 25~, thence out of the housing 31~, which en-
closes the space between first and second partitions 23~, 25~. hn irllet45' in housing 31~ provides communication for the steam to annular passages
21', as shown by the dotted-line arrows 59'. Water enters inner passages
19' by a first manifold (not shown) similar to that in the embodiment of
Figures 1 through 3, as shown by the solid-line arrows 57'. This embodiment
does not re~uire a baffle between the first and second partitions 23
25~ because of conduit 61, which serves as part of the third manifold
means for directing second fluid out of the heat exchanger. The steam
exchanges heat primarily when in the annular passages 21l.
Figure ~ discloses an embodiment primarily for use in a storage
tank 63, with most of the length of the concentric tubes being on the
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interior of the tank and surrounded by liquid discharged from the inner
passagesO The inner tubes 17" extend parallel~to each other and are
connected by conventional means to the liquid to be heated. ~uter tubes
15" are connected by conventional L-shaped fittings 65 to the source and
return of the heating fluid. ~t the second or interior end of the heat
exchanger, the outer tubes l5" are closed and connected together by a
passage 67. A jacket Sl', with a closed interior end, extends around the
concentric tubes and terminates at the wall of the storage atank 63. hn
outlet 55' is provided in jacket!5l' at the tank 63 wall to allow fluid
discharged from the inner passage l9' to flow into the storage tank.
In operation, the liquid to be heated enters the inner passage
l9~ of each concentric tube as shown by the solid-line arrows 57". After
heating, the fluid discharges from the second end, flows back overi~the outer
tubes 15" within jacket 51', and then out into storage tank 63. The
heating fluid enters one of the inlet connections 65 and flows through one
of the annular passages 2l", as shown by the dotted-line arrows 59", with
connection 65 serving as the second manifold. The second fluid enters
passage ~67 at the second end and flows back down into the other annular
passage 21" and out connection 65, this connection and passage 67 serving
as the third manifold means. Heat is exchanged through the walls of the
inner tube 17" and outer tube 15"~ Since the heat exchanger of this
embodiment is suspended only at a point intermediate its ends, the concentric
tubes are free to expand and contract due to thermal changes.
It should be apparent that an invention having significant
improvements has been provided. By forcing all of the incoming fluids ~}
through the inner and annular passages of the concentric tubes~ both fluids
can flow at high velocities. Greater efficiency is achieved by immersing -
the outer tubes in the fluid of the inner passage, causing heat to be
transferred across the walls of both the inner and outer tubes. This is
particularly efficient when using the jacket, which reverses the direction
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of flow of the fluid of the inner tube and causes fluid flow back across
the outer tubes. The ends of the concentric tube-pairs are not restrained,
allowing change in length due to thermal changes.
Having described the invention in connection with certain
embodiments thereof, it should be apparent to those skilled in the art
that it is not so limited but is susceptible to various changes and modi-
fications without departing from the spirit thereof.
