Note: Descriptions are shown in the official language in which they were submitted.
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RECUPERATOR DESIGN
Background of the Invention
Field of the Invention. This invention relates to a struc-
tural arrangement for a concentric tube heat exchanger and particularly
it relates to a unique support for a modular tube type heat exchanger
wherein a heating fluid flowing outside the tubes thereof transmits
heat to a second fluid flowing through the space between the concentric
tubes.
Description of the Prior Art. Recuperative heat exchangers
employing a series of concentric tubes are frequently used to transfer
heat from hot combust~on gases to cool air being supplied for combus-
tion. The exhaust or waste gases are usually at extremely high tem-
peratures when they enter the chamber of the heat exchanger in which
the tubes are located and thus adversely affect the recuperator tubes
and the housing in which they are supported. Moreover, differential
expansion between tubes and housing structure damages any connection
therebetween, so structural integrity of the heat exchanger is com-
promised and the heat exchanger is frequently forced to operate at
less than maximum efficiency.
Examples of conventional heat exchange art are to be found
in U.S. Patent #3,586,098 and U.S. Patent #2,670,945 where tube sheets
supporting tubular heat exchangers are rigidly connected to inlet and
outlet headers before being rigidly connected to surrounding housing
structure. The temperature gradient inherent in devices of this type
effects relative expansion and contraction of the several parts, and
breakage of the weldments therebetween is common. Moreover, conven-
tional heat exchangers of this type are excessively large and they
frequently utilize extensive amounts of transverse ducting which may
~e e~tre~e~y ~i~ficu~t tc ~it intc e~isting space a~t~ents.
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Summary of the Invention
The present invention relates to a heat exchanger of the
concentric tube type wherein various parts thereof are pivotally
mounted so they may thermally expand or contract without breaking a
connecting bond therebetween. Moreover, the heat exchanger is com-
prised of adjacent modules having an integral ducting arrangement
that precludes excess material requirements, reduces weight, and
eliminates excessive external ducting. A plurality of modules is
connected to permit serial flow of fluid therethrough, and the heat
exchanger is designed to permit a maximum utilization of available
heat.
Accordingly, the principle object of this invention is to
provide a modular type tubular heat exchanger that is economical to
manufacture, remains structurally sound throughout a wide range of
temperature variations, and one which essentially eliminates external
ducting.
Moreover, the elements of this heat exchanger are of modular
construction that may be arranged serially to provide increased capac-
ity, while ducting for the several fluids is adapted to-provide maximum
utilization of available heat.
Brief Description of the Drawing
These and further advantages will be more completely dis-
closed and described in the following specification and the accompany-
ing drawing in which:
Figure 1 is a perspective view, partially broken away to
show a series of adjacent modules, and
Figure 2 is an enlarged perspective view showing the struc-
tural details of a single module.
Description of the Preferred Embodiment
Referring to Figure 1 of the drawing, the numeral 12 generally
refers to a recuperative type concentric tube heat exchanger that is
comprised of a series of identical modules 14 supported in lateral
juxtaposition and having the internal elements thereof supported so as
to permit independent expansion of their several parts caused by in-
herent thermal differences.
1 ~55834
Each module 14 includes a hous~ng that encloses upper and
lower tube sheets 22-24 that are spaced apart in parallel planes to
provide an upper compartment 26 above the tube sheets, a compartment
28 below the tube sheets, and a compartment 32 therebetween. The tube
sheets 22-24 are provided with vertically aligned apertures, the aper-
tures in the lower tube sheet 24 being somewhat larger than the aper-
tures in upper sheet 22 whereby tubes 36 depending from the apertures
of the upper tube sheet hang inside the tubes 38 that depend from the
larger apertures of the lower tube sheet to provide an annular flow
passageway 40 therebetween.
An inlet 34 is provided to admit a cool fluid to be heated
to the space between tube sheets 22-24 whereby it will flow into the
annular space between tubes in heat exchange relation with a heating
fluid flowing through the lower compartment 28. After the cool fluid
traversing annular passageway 40 reaches the closed end of the outer
tube it is reversed to flow upwardly through inner tube 36 to the
upper compartment 26 where an outlet duct 42 directs the heated fluid
to its place of final use.
The cool inlet air of compartment 32 accordingly lies between
the heating fluid traversing compartment 28 and the heated fluid of
compartment 26 being exhausted through outlet port 42. Thus, cool
fluid from inlet 34 in compartment 32 lies between the heating fluid
of duct 28 and the heated fluid of duct 26 whereby said cool fluid is
in a position to effectively absorb heat from hot fluids at either
side thereof.
The tube sheets and dependent tubes of each module are sup-
ported from a pair of lateral beams 44 that lie at the sides of each
module, the ends of the beams 44 in turn being supported in frames 46
that are connected to end panels 48 forming the outer housing of each
module. The beams extend laterally across the inlet of each module
to provide flow passageways above and below the beam 44 whereby each
beam is subjected to the consistently lower temperature of the fluid
~ to be heated and thus subject to a minimum of thermal deformation.; The basically stable transverse beams 44 are then used as
a base to which the upper tube sheet 22 and the lower tube sheet 24
are pivotally secured. Flanges 54 at the end edges of the tube sheets
are thus connected by links 52A and 52B to the beams 44 whereby any
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differential of expansion will be reflected in movement of the linkage
means about connections 50.
Flanges 54 at the end edges of the tube sheets have aper-
tures that permit bolting together of adjacent beams to increase the
capacity of a given heat exchanger, while similar apertures in flanges
around the end edges of panels 48 permit joining of adjacent units or
the bolting in place of end plates that include passageways for the
relatively hot and cold fluids. One end plate includes the inlet 34
for the fluid to be heated and an outlet for the hot fluid exhausting
from compartment 28, while the opposite end plate includes an outlet
42 for the heated fluid and an inlet for hot fluid being directed into
the compartment 28 and over the outside of tubes 38.
