A structural support for a module of a concentric tube type recuperative heat exchanger. A plurality of support beams 18 extend laterally across each module to support upper and lower tube sheets 22-24 independent from surrounding housing structure. The support beams are attached to the tube sheets by pivotal hangers 26 that permit relative movement therebetween, while said support beams are themselves supported at their ends on lateral shelf units affixed to the housing that surrounds each module.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a structural 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. 
2. Description of the Prior Art 
Recuperative heat exchangers employing a series of concentric tubes are 
frequently used to transfer heat from hot combustion gases to cool air 
being supplied for combustion. The exhaust or waste gases are usually at 
extremely high temperatures 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 
compromised 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. Pat. No. 
3,586,098 and U.S. Pat. No. 2,670,945 where tube sheets supporting tubular 
heat exchangers are rigidly connected to inlet and outlet headers before 
being rigidly connected to surroundig 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, conventional heat exchangers of this 
type are excessively large and they frequently utilize extensive amounts 
of transverse ducting which may be extremely difficult to fit into 
exisiting space allotments. 
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 comprised 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 capacity, while ducting 
for the several fluids is adapted to provide maximum utilization of 
available heat.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 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 inherent thermal differences. 
Each module 14 includes a housing that encloses upper and lower tube sheets 
22-24 that are spaced apart in with the ends of said sheets slidably 
abutting elongate flanges 25 carried by the housing walls 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 apertures in the lower 
tube sheet 24 being somewhat larger than the apertures 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 supported 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 by protrusion 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 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 apertures 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 form 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.