AU481237B2 - Revolving linear tube heat exchanger - Google Patents

Description

58.819F Background of the Invention i. Field of the Invention

This invention relates to a heat exchange

device having movably supported surface means exposed

for contact with material to be heated, and more parti-

cularly, wherein said movable surface means is part of a

hollow rotating device through which heating fluid flows.

Such a heat exchange device can be used as a concentrat-

ing evaporator by the food industry to make high density

food products such as tomato paste, strawberry pre-

serves, etc. 2. Description of the Prior Art

Rotary steam coil devices have been used in

evaporators for heating food products. Normally, such

rotary coils are formed with tubing having a circular

cross-section and helical shape about the axis of rota-

tion of the coil. Steam is passed through the tubing as

the coil is rotated within the product to be heated. It has been found that as such coils rotate,

a cavity develops within the product on the trailing

side of the tubing due to the velocity of the tubing

moving through the product and the viscosity of the pro-

duct. A thin film of product adheres to the hot trailing edge of the tubing adjacent the cavity and there is a

tendency for this film to burn and give a detrimental

flavor to the finished product. 21o, 3,6'3A58, In the United States patentaplcc

CSerifl lie. filed September 29, 1969, and having

a common co-inventor with the present application, the

above problem was disclosed, and it was therein suggested 481.237

58.819 73 that the trailing portion of the heat-exchanger coil tubing

could be made less heat conductive than the rest of the coil

by adding insulating material to the trailing portion or by

forming an air chamber within the tubing adjacent the trailing edge.

Summary of the Invention

According to the present invention there is

provided a heat-exchanger comprising an elongated tank for

receiving a liquid to be heated, a hollow rotatable shaft

supported at one end of said tank for rotation about a

longitudinal axis, a tubular connecting portion in communi-

cation with and projecting from a portion of the shaft located

within the tank in a direction outward from said longitudinal

axis, and at least one linear tube communicating with said

connecting portion and extending within the tank parallel to

but spaced from said longitudinal axis, said tube being

rotatable in an orbital path about said longitudinal axis

upon rotation of said shaft, said shaft, said connecting to "ret portion and said tube together forming a c nduit-" 4

heating fluid t #t:i to heat th iqu z.

4;n said linear tube being divided longitudinally to form

a heating fluid portion adjacent the leading edge thereof,

defined with reference to its direction of movement in said

orbital path, and an insulating portion adjacent the trailing

portion of the tube to insulate that portion from the heating

fluid portion and thereby reduce the tendency for solids in

the liquid in the tank to burn on to the exterior surface

of the tube.

Brief Description of the Drawings A 48 1,237

58.819/73 Figure 1 is a longitudinal section of a heat

exchanger embodying the present invention.

Figure 2 is an enlarged transverse section

taken on the line 2-2 of Figure i.

Figure 3 is an enlarged transverse section

taken on the line 3-3 of Figure 1 and showing a tube

through which heating fluid flows with insulation on the

inner trailing portion thereof and with a streamlined

transverse surface configuration.

Figure 4 is a transverse section of a modi-

fied form of tube.

Figure 5 is a transverse section of a second

modified form of tube.

Figure 6 is a transverse section of a third

modified form of tube.

Figure 7 is a side elevation of a rotary

heating element illustrating a modified form of the in- vent ion.

Figure 8 is an enlarged transverse section

taken on the line 8-8 of Figure 7.

Figure 9 is a longitudinal section of a second

modified form of heat exchanger.

Figure 10 is an enlarged transverse section

taken on the line 10-10 of Figure 9.

Description of the Preferred Embodiments

Looking first at Figure i, a heat exchanger

has a tank 11 with an inlet 12 through which liquid to

be heated enters and an outlet 13 from which heated

liquid is discharged. The tank is preferably of a hollow

cylindrical shape enclosed by a left end plate 14 and a A 48 1,237

58.819 /73 right end plate 15. A sleeve bearing 16 defines a shaft

opening through the left end plate and a similar sleeve

bearing 17 defines a shaft opening through the right end

plate.

A hollow shaft 20 is journalled within sleeve

bearing 16 in left end plate 14 for rotation about an

axis 21 and tubular spokes 22, 23 and 24 projecting

outward from the shaft are coupled with a ring-shaped

conduit 25. A series of tubes 26 extend from conduit

parallel with axis 21 to a second ring-shaped conduit 27. Tubular spokes 28, 29 and 30 connect conduit 27

with a hollow shaft 31 journalled in sleeve bearing 17.

It will be further noted, from Figure i, that each

tubular spoke has an oblong transverse shape and is

inclined to propel liquid within tank 11 in the direction 'of an arrow 32 upon normal rotation of the shafts.

With reference to Figure 2, shaft 31 rotates

counterclockwise in the direction of arrow 33 and each

tube 26 has a streamlined transverse surface configura-

tion whereby liquid can flow thereabout with a sub-

stantially unbroken flow. This configuration tends to

prevent a void from forming in the liquid behind a mov-

ing tube. Each tubular spoke is curved along a spiral

path extending from conduit 27 rearwardly opposite to

the direction of rotation for connecting in substantially

radial alignment with shaft 31. This curvature of the

spokes enables condensate from heating fluid which

collects in the bottom of conduit 27 to be fed through

the tubular spokes to shaft 31 and thereby pass out of

the heat exchanger structure. r 48 1.237

58.81 9/73 Figure 3 shows the interior of a tube 26 and

it will be noted that an insulating or low heat conduc-

tion material 34 has been filled into the trailing por-

tion 35 of the tube. Teflon, lead, or solder can be used as the insulating material inside the tube or as an

alternative illustrated in Figure 4, the exterior trail-

ing portion 35a of a modified tube 26a could be coated

with an insulating and non-sticking material such as

Teflon. Another alternative illustrated in Figure

would provide an air cell 36a between the trailing por-

tion 35b of a second modified tube 26b and a heating

fluid conduit 36b therein. Thus, the exterior trailing portion of the tube can be insulated from heating fluid

within the tube and this reduces the tendency for a

film of liquid to burn thereon. A further alternative illustrated in Figure 6 provides a third modified form

of ube 26c of a generally triangular transverse surface

configuration and having an air cell 36c along the

trailing base portion thereof for insulating that portion

from heat within a heating fluid conduit 36d. While Zh trznevcrzz curface canfiguration i ieatalincd and a void would develop in liquid behind the tube, insula-

tion provided by the air cell is sufficient to prevent

burning of a film of liquid on the trailing portion of

the tube.

In operation, heating fluid such as steam is

fed through shaft 20 in the direction of an arrow 37

and from that shaft, the heating fluid flows through

tubular spokes 22, 23 and 24, conduit 25, tubes 26,

conduit 27, tubular spokes 28, 29 and 30, and shaft 31 6 48 1,237

58,819 /73 to discharge from the heat exchanger structure. Liquid

to be heated enters tank 11 through inlet 12 and flows

toward outlet 13 due to pressure differential and the

current developed in the direction of arrow 32 by the

tubular spokes. Rotation of shafts 20 and 31 causes

tubes 26 to revolve in an orbital path about axis 21 and

heat is transferred from the tubes to the liquid within

the tank. The tendency for a film of liquid on the

trailing edge of tubes 26 to burn is inhibited by the

streamlined shape of the tubes and insulation thereon. The alignment of tubes 26 generally parallel

to the axis of revolution 21 provides that the trailing edge of each tube will follow a straight line. This

simplifies fabrication of the tubes with streamlined and

insulated trailing portions.

A modified form of the invention is illustrated

in Figures 7 and 8. A rotary heating element 40, shown

in Figure 7, has a hollow shaft 41 from which tubular

spokes 42, 43 and 44 project and tubes 45 extend there-

from parallel with the axis of. rotation of the shaft to

tubular spokes 46, 47 and 48 (Fig. 8) which project from

a tubular shaft 49 aligned with the tubular shaft 41. It

will be noted in Figure 8 that tubes 45 are mounted for

communication with the tubular spokes at different radial

distances from shaft 49. This tends to stagger tubes

within the enclosed heat exchanger tank and thereby

eliminate the possibility of a void forming along a

circular path within the liquid being heated because of insufficient spacing between tubes. A second modified form of the invention is 9 48 1.237

58,819 73 illustrated in Figures 9 and 10 wherein a heat exchanger

has a tank 51 with an inlet 52 and an outlet 53.

Liquid to be heated is pumped upward through the inlet

and flows vertically through the tank to the outlet. A hollow rotatable shaft 55 is journalled in

a sleeve bearing 56 mounted in the top of tank 51. Four

tubular spokes 57 (only one spoke being shown) project

outward from shaft 55 to a ring shaped conduit 58 and

tubes 59 depend therefrom to a ring shaped conduit

coupled by tubular spokes 61, 62, 63 and 64 to a hollow

rotatable shaft 65. This latter shaft is journalled in

a sleeve bearing 66 mounted in the bottom of the tank. The tubular structure revolves in the direction

of an arrow 67 (Fig. 10), and tubular spokes 57, 61, 62,

63, and 64 have an oblong shape inclined rearwardly and

upwardly with reference to the direction of motion

thereof in order to assist in forcing liquid upward

through tank 11. Heating fluid flows downward through

the tubular structure so that no problem develops in

the event of condensation therein.

Although the best modes contemplated for carry-

ing out the present invention have been herein shown and

described, it will be apparent that modification and variation may be made without departing from what is

regarded to be the subject matter of the invention.

8 48 1237

Claims (2)

1. 58g819P3 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

   i. A heat-exchanger comprising an elongated tank for

   receiving a liquid to be heated, a hollow rotatable shaft

   supported at one end of said tank for rotation about a longi-

   tudinal axis, a tubular connecting portion in communication

   with and projecting from a portion of the shaft located within

   the tank in a direction outward from said longitudinal axis,

   and at least one linear tube communicating with said connecting

   portion and extending within the tank parallel to but spaced

   from said longitudinal axis, said tube being rotatable in an

   orbital path about said longitudinal axis upon rotation of

   said shaft, said shaft, said connecting portion and said tube h !6 together forming a conduitliwic heating fluidli

   Lir e to heat the liquid in/e tank, said linear tube

   being divided longitudinally to form a heating fluid portion

   adjacent the leading edge thereof, defined with reference to

   its direction of motion in said orbital path, and an insula-

   ting portion adjacent said trailing portion of the tube to

   insulate that portion from the heating fluid portion and

   thereby reduce the tendency for solids and the liquid in the

   tank to burn on to the exterior surface of the tube.
2. 2. A heat-exchanger according to claim 1 wherein said

   insulating portion of the tube comprises an air cell.

   3. A heat-exchanger according to claim 1 or claim 2

   wherein said tube has a cross-sectional configuration of

   generally triangular shape.

   4. A heat-exchanger according to claim i, claim 2 or

   claim 3, comprising a pair of said hollow rotatable shafts

   supported at opposite ends of the tank and first and second

   of said tubular connecting' portions each being in communication Q 48 1,237

   58.819 173 with one of said hollow rotatable shafts.

   A heat-exchanger according to claim 4 wherein each of said tubular connecting portions includes a ring-shaped

   conduit concentric with the corresponding hollow rotatable

   shaft and a plurality of tubular spokes connecting the ring-

   shaped conduit with the hollow rotatable shaft, each of said

   tubular spokes forming a generally spiral path from the ring-

   shaped conduit to the hollow rotatable shaft in a direction

   opposite to the direction of rotation of the ring-shaped

   conduit. 6. A heat-exchanger according to any one of the preceding claims wherein each of said tubular connecting

   portions includes portions inclined to the direction of

   rotation thereof for propelling liquid within the tank longi-

   tudinally thereof. 7. A heat-exchanger according to claim 5 wherein said

   tubular spokes are angled to the direction of rotation thereof

   for propelling liquid longitudinally within the tank.

   8. A heat-exchanger according to any of claims 1 to 3 wherein said tubular connecting portion includes a ring-shaped

   conduit and a multiplicity of tubes extending from said ring-

   shaped conduit at uniform radial spacing from the longitudinal

   axis of rotation. 9. A heat-exchanger according to claim 1 including a multiplicity of tubes extending from said tubular connection

   at staggered radial spacing from the longitudinal axis of

   rotation to maintain unbroken flow of liquid about the tubes.

   A heat-exchanger according to any of the preceding claims wherein the common longitudinal axis of the

   rotatable shaft is vertical.

   0 48 1237

   58,819 73 as hereinbefore 11. A heat-exchanger substantially drawings. described with reference to the accompanying

   DATED THIS 2ND DAY OF JULY, 1976.

   FMC CORPORATION By Its Patent Attorneys:

   CLEMENT HACK CO.

   Fellows Institute of Patent Attorneys of Australia.

   48 1,237

   58,81 9/73

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