US3363679A

US3363679A - Heat exchangers

Info

Publication number: US3363679A
Application number: US572628A
Authority: US
Inventors: Ernest Walter
Original assignee: AMERICAN SCHACK CO Inc
Current assignee: AMERICAN SCHACK CO Inc
Priority date: 1963-11-07
Filing date: 1966-08-15
Publication date: 1968-01-16
Anticipated expiration: 1985-01-16
Also published as: GB1027195A

Description

Jan. 16, 1968 w, ERNEST 3,363,679

HEAT EXCHANGERS Original Filed Nov. 9, 1964 15% zmmfw A FOP/V5 VS United States Patent 3,363,679 HEAT EXCHANQERES Walter Ernest, London, England, assignor, by rncsne assignments, to The American Schach Company, Inc, Pittsburgh, Pa, a corporation of Delaware Continuation of application Scr. No. 409,533, Nov. 9, 1964. This application Aug. 15, 1966, Ser. No. 572,628 Claims priority, application Great Britain, Nov. '7, 1963, 44,054/ 63 10 Claims. (Cl. 165-141) This is a continuation of application Ser. No. 409,883, filed Nov. 9, 1964, now abandoned.

The invention relates to heat exchangers and particularly to dual flow heat exchangers.

Known heat exchangers have the disadvantage that the outlet temperature of the fluid of the secondary cycle can only be regulated by varying the rates of flow or inlet temperatures of one or both of the cycles.

The invention has among its objects to provide a heat exchanger in which the rate of exchange of heat is readily Changeable.

According to the invention there is provided an cxchanger for heat transference between fluids at different temperatures comprising a circuit for a primary fluid and at least two secondary circuits of different lengths having a common outlet for a secondary fluid.

According to the invention furthermore means are provided for varying the ratio of rates of flow of secondary fluid in the secondary circuits to control the temperature of the fluid at the common outlet.

Thus the exchanger may be provided as an upright elongated body formed of three concentric tubes, the inlets to the two secondary circuits being provided at the upper end of the two innermost tubes and the primary fluid flowing in the annular space between the outermost tube and the next innermost tube. This space is also provided with two helical coils through which passes the secondary fluid. The innermost tube is in communication With the lower coil at the lower end and the next outermost tube is in communication with the upper coil at a position intermediate the ends of the exchanger. At this position the two coils are in communication with one another. Thus two secondary circuits are formed one comprising theinnerrnost tube and the lower and upper coils, and the other comprising the next innermost tube and the upper coil. The circuits have a common outlet.

According to the invention further, the innermost tube, the next innermost tube and the upper and lower coils are provided to be readily removable from the exchanger whereby the coils may be replaced by other coils having a different ratio of effective lengths one to another.

Thus the two inner tubes and the coils may be supported by a flanged cap Which is supported by the outermost tube, which tube is advantageously lined with a refractory material, in such manner that they may easily be lifted out and replaced by other tubes and coils.

According to the invention moreover, the means for controlling the outlet temperature of the fluid from the secondary circuits comprises valve means adapted to regulate the rate of flow of fluid to each part of the secondary circuit.

The invention is diagrammatically illustrated by way of example in the accompanying drawing which is a sectional elevation of a heat exchanger according to the invention.

As shown the heat exchanger comprises three vertical

concentric tubes

1, 2 and 3, the outer tube 3 being lined with a refractory material 4. A central circular space 5 and annular spaces 6 and 7 are thus formed. The annular space 7 is provided with advantageously spiral

tubular coils

8 and 9. The space 5 is in communication "ice with the coil 8 through a header 10 and the space 6 is in communication with the coil 9 by means of a header 11. The

coils

8 and 9 are in communication one with another by means of the header 11. A further header 12 is provided at the upper end of the coil 9 communicating with an outlet port 13. A port 14 communicating with the space 7 is provided at the upper end of the exchanger as inlet for the primary fluid, and a port 15 is provided at the lower end of the exchanger for outlet of the primary fluid. The fluid for the secondary circuits enters by a pipe line 16 and passes by way of a valve 17 and

pipes

18 and 19 to

inlet ports

20 and 2 1 communicating with the

spaces

5 and 6 respectively.

In operation the fluid passes from line 16 to the valve 17 where it is split into two streams to pass along

pipes

18 and 19. The fluid from pipe 18 passes down the central space 5 to the lower end of the exchanger where it enters the coil 8 by means of the header 10. Fluid from pipe 19 passes down the space 6 to the: header 11 where it mixes with fluid from the coil 8. The mixed fluids pass through the coil 9 to the header 12 and out of the exchanger at the port 13. During the time that it is passing through the

coils

8 and 9 it is in heat-exchanging relation through the walls of the coil tubes with the primary fluid which is passing over the coils in the space 7. Assuming that the primary fluid is at a higher temperature than the secondary fluid, the secondary fluid will be heated as it passes through the exchanger. It is apparent that the fluid from the pipe 18 takes a longer path through the exchanger than the fluid from the pipe 19 and thus will absorb more heat from the primary fluid. Thus by regulating the proportion of flow supplied to the

spaces

5 and 6 the outlet from port 13 can be regulated between the limits of very hot, that is to say all the fluid supplied through space 5, and cool, that is to say all the fluid supplied through space 6.

The invention further includes the feature that two feeds of secondary fluid can be applied to the exchanger at diiferent temperatures. Feed pipe 22 communicating with pipe 18 and feed pipe 23 communicating with pipe 19 are provided for this purpose. Thus a cool fluid supplied through pipe 22 passes through space 5 and coil 3 and by the time it reaches header 11 is raised to approximately the same temperature as a relatively hot fluid supplied through pipe 23 and space 6. Flow control valves 24, 25 are provided on the pipes 22, 23 respectively.

The ratio of lengths of the

coils

8 and 9 may easily be changed by splitting the joint 26 and removing the tube bundle formed by tubes 1 and 2 and

coils

8 and 9 from the outer tube 3 and replacing them by a further tube bundle comprising coils and tubes of the desired lengths.

I claim:

1. A heat exchanger, comprising:

an outer casing having a fluid inlet and a fluid outlet arranged so that a first fluid can flow from said inlet through said casing to said outlet,

a first conduit extending into said outer casing, said first conduit having a closed end portion within said outer casing spaced from the inner surface or" said casing and an open end portion externally of said outer casing and forming an outlet port for a second fluid,

a second conduit extending into said first conduit and having an open end portion externally of said first conduit and forming an inlet port for said second fluid, said second conduit having an end portion positioned within said first conduit,

said second conduit spaced from said first conduit and forming a first chamber between the outer surface of said second conduit and the inner surface of said first conduit,

means connecting a portion of said second conduit outer surface to said first conduit inner surface and forming a second chamber within said first conduit communicating with said second conduit and providing a flow path for said second fluid between said second conduit and said second chamber within said first conduit, and

a plurality of heat exchange tubes communicating at one end with said first chamber and at the other end with said second chamber and thereby forming a flow path for said second fluid between said second chamber and said first chamber.

2. A heat exchanger as set forth in claim 1 in which said outer casing includes a cylindrical vertical shell having a closed top portion and a bottom portion forming a heat exchange chamber therein,

said top portion having an aperture therethrough, and

said first conduit extending through said aperture and secured to said top portion so that said first conduit is suspended in said heat exchange chamber from said top portion with said first conduit closed end portion spaced from the inner surface of said bottom portion.

3. A heat exchanger as set forth in claim 1 in which said second conduit is arranged concentrically within said first conduit and forming an annular first chamber therebetween for receiving said second fluid from said heat exchange tubes.

4. A heat exchanger as set forth in claim 2 in which said second chamber extends to a location adjacent said vertical shell bottom portion and said first chamber is positioned adjacent said vertical shell closed top portion and said heat exchange tubes extend substantially throughout the length of said vertical shell between said second chamber and said first chamber.

5. A heat exchanger, comprising:

an outer casing having a fluid inlet and a fluid outlet arranged so that a first fluid can flow from said inlet through said casing to said outlet, first and second conduit means disposed within said casing in heat exchange relation with the fluid flowing between the inlet and the outlet of said casing, the first and second conduit means having corresponding one ends connected to each other so that a second fluid can flow in series through both conduit means,

first supply means for supplying the second fluid to the other end of said first conduit means and second supply means for supplying the second fluid to a point in circuit between the two conduit means whereby the second fluid is supplied at two different points to said conduit means,

a common outlet for the second fluid connected to the other end of the second conduit means, and

means for controlling the rates of flow of the second fluid through the first supply means and the second supply means to control the temperature of the secnd fluid at the common outlet.

6. An exchanger according to claim 5, in which said means for controlling the rates of flow in the first and second supply means comprises valve means adapted to regulate the rate of flow of fluid to each of said supply means,

7. A heat exchanger according to claim 5, in which said casing and said first and second supply means are defined by three spaced-apart concentric tubes, the outermost tube forming said casing and having said inlet and said outlet for said first fluid connected thereto so that the first fluid flows through the space between the outermost tube and the intermediate tube, the innermost tube forming one of said supply means and the space between the innermost tube and the intermediate tube forming the other of said supply means.

8. A heat exchanger according to claim '7, in which said conduit means are each provided by helically coiled piping located in the space between said outermost tube and said intermediate tube; the two conduit means being arranged in cnd-to-end relation within said space.

9. An exchanger according to claim 8, in which one end of said first conduit is in communication with said innermost tube, the other end of said first conduit is in communication with the adjacent end of said second conduit and with said intermediate tube and the other end of said second conduit being in communication with said common outlet.

16. A heat exchanger, comprising:

an elongated outer tube having an inlet port adjacent one end thereof and an outlet port adjacent the other end thereof, an intermediate tube and an inner tube disposed within and spaced from said intermediate tube, said intermediate tube being disposed concentrically within and spaced from said outer tube, said inner tube defining a central opening and the space between said intermediate and inner tubes defining an annular passageway surrounding and isolating from said central opening, two sets of heat exchange conduits disposed in the space between said outer tube and said intermediate tube and arranged in end-to-end relation therewithin,

means connecting said central opening to one end of one of said sets of conduits so that fluid flowing through said central opening will flow through said one set of conduits,

means connecting the other end of said one set to one end of the other set and means connecting said annular passageway to said one end of said other set so that fluid flowing through said one set and fluid flowing through said annular passageway will both flow through said other set,

means providing a common outlet connected to the other end of said other set, and

means for supplying fluid to said central opening and said annular passageway at individually controllable rates of flow in order to control the temperature of the fluid at the common outlet.

No references cited.

ROBERT A. OLEARY, Primary Examiner.

T. W. STREULE, Assistant Examiner.

Claims

1. A HEAT EXCHANGER, COMPRISING: AN OUTER CASING HAVING A FLUID INLET AND A FLUID OUTLET ARRANGED SO THAT A FIRST FLUID CAN FLOW FROM SAID INLET THROUGH SAID CASING TO SAID OUTLET, A FIRST CONDUIT EXTENDING INTO SAID OUTER CASING, SAID FIRST CONDUIT HAVING A CLOSED END PORTION WITHIN SAID OUTER CASING SPACED FROM THE INNER SURFACE OF SAID CASING AND AN OPEN END PORTION EXTERNALLY OF SAID OUTER CASING AND FORMING AN OUTLET PORT FOR A SECOND FLUID, A SECOND CONDUIT EXTENDING INTO SAID FIRST CONDUIT AND HAVING AN OPEN END PORTION EXTERNALLY OF SAID FIRST CONDUIT AND FORMING AN INLET PORT FOR SAID SECOND FLUID, SAID SECOND CONDUIT HAVING AN END PORTION POSITIONED WITHIN SAID FIRST CONDUIT, SAID SECOND CONDUIT SPACED FROM SAID FIRST CONDUIT AND FORMING A FIRST CHAMBER BETWEEN THE OUTER SURFACE OF SAID SECOND CONDUIT AND THE INNER SURFACE OF SAID FIRST CONDUIT, MEANS CONNECTING A PORTION OF SAID SECOND CONDUIT OUTER SURFACE TO SAID FIRST CONDUIT INNER SURFACE AND FORMING A SECOND CHAMBER WITHIN SAID FIRST CONDUIT COMMUNICATING WITH SAID SECOND CONDUIT AND PROVIDING A FLOW PATH FOR SAID SECOND FLUID BETWEEN SAID SECOND CONDUIT AND SAID SECOND CHAMBER WITHIN SAID FIRST CONDUIT, AND A PLURALITY OF HEAT EXCHANGE TUBES COMMUNICATING AT ONE END WITH SAID FIRST CHAMBER AND AT THE OTHER END WITH SAID SECOND CHAMBER AND THEREBY FORMING A FLOW PATH FOR SAID SECOND FLUID BETWEEN SAID SECOND CHAMBER AND SAID FIRST CHAMBER.