GB1585045A

GB1585045A - Heat exchanger with double walled tubes

Info

Publication number: GB1585045A
Application number: GB2066478A
Authority: GB
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1977-06-28
Filing date: 1978-05-19
Publication date: 1981-02-18
Also published as: JPS6051639B2; JPS5417558A; FR2396261B1; FR2396261A1; DE2822999A1; DE2822999C2

Description

(54) HEAT EXCHANGER WITH DOUBLE WALLED TUBES (71) We WESTINGHOUSE ELEC TRIC CORPORATION of Westinghouse Building, Gateway Center, Pittsburgh, Pennsylvania, United States of America, a corporation organised and existing under the laws of the State of Pennsylvania, United States of America do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to heat exchangers and more particularly to heat exchangers utilizing double walled tubes to reduce the possibility of contact between the heating and the heated fluid.

It is normally desirable to separate heating and heated fluid in a heat exchanger and depending on the compatibility of the fluids the effort and expense expended to insure separation varies. Double walled tubes with grooves in one of the contacting walls have been proposed as being highly reliable. In such arrangements double walled tubes are so disposed between a pair of spaced apart tube sheets that the outer tube terminates at an inner tube sheet and the inner tube terminates at an outer tube sheet. However, the tube to tube sheet joints are in an area where the probability of leakage is high even when spaced apart tube sheets are utilized and the inner wall of the tube is seal welded to one tube sheet and the outer wall is seal welded to the other tube sheet.

It is therefore the principal object of the present invention to provide a heat exchanger in which the space between the tube sheets is readily accessible for inspection and/or repair.

With this object in view, the present invention resides in a heat exchanger comprising a shell, a plurality of double walled tubes supported in said shell and having an inner tube portion disposed within an outer tube portion, said inner and outer tube portions being mounted at one end respectively in outer and inner tube sheets disposed in a spaced relationship within said shell, characterized in that said shell includes a removable portion (17) enclosing the space between the inner and outer tube sheets (9, 11), said shell portion 17 having a radially outwardly extending flange (21) adjacent the inner tube sheet (9) and a radially inwardly extending flange (19) disposed adjacent the outer tube sheet (11) and connected to an outwardly extending flange (22) of said outer tube sheet (11) said tube sheet flange (22) being disposed within the removable shell portion (17) so as to permit axially sliding removal of said shell portion (17) over said tube sheet flange (22).

The invention will become more readily apparent from the following description of a preferred embodiment thereof shown, by way of example only in the accompanying drawing, in which: The sole figure is a partial sectional view of a heat exchanger made in accordance with this invention.

Referring now to the drawing in detail, there is shown a portion of a heat exchanger 1 having a plurality of double walled tubes 3 disposed therein. The double walled tubes are made up of an inner wall 5 engagingly disposed within an outer wall 7. A pair of tube sheets 9 and 11 are disposed generally parallel to each other in a spaced relationship adjacent one end of the tubes 3. The tubes 3 pass through holes 13 and 15 in the tube sheets 9 and 11, respectively, and are so arranged with respect thereto that the ends of the outer walls 7 terminate adjacent the inner tube sheet 9 and are seal welded thereto and the ends of the inner walls 5 terminate adjacent the outer tube sheet 11 and are seal welded thereto.

A portion of the shell 17 is cooperatively associated with the tube sheets 9 and 11 so as to enclose the space therebetween and be removably connected thereto. The portion of the shell 17 is flanged at each end. One end has a flange 19 which extends radially inwardly from the portion of the shell 17 and the other end has a flange 21 which extends radially outwardly from the portion of the shell 17.

The inwardly extending flange 19 cooperates with an outwardly extending flange 22 that is welded to the head 11 and a gasket 23 to form a seal therebetween. The outwardly extending flange 21 cooperates with an outwardly extending flange 25 and seal ring 27 to form a seal therebetween.

The inwardly and outwardly extendingflanges 19 and 21, respectively, allow the shell portion 17 to be removed from the heat exchanger.

The shell portion 17 has a bellows 29 or other expansion means disposed therein to allow for differential expansion between the inner wall 5 of the tube 3 and the shell portion 17. The bellows 29 also compensates for any misalignment between the. flanges and assists in aligning the flanges when installing the shell portion 17.

The arrangement hereinbefore described provides a removable shell portion 17 for allowing access to the welds between the outer wall 7 and the inner tube sheet 9; provides for differential expansion between the inner wall 5 of the tubes 3 and the shell portion 17; and provides for accommodating misalignment within the flanges 19 and 22 and 21 and 25.

WHAT WE CLAIM IS: 1. A heat exchanger comprising a shell, a plurality of double walled tubes supported in said shell and having an inner tube portion disposed within an outer tube portion, said inner and outer tube portions being mounted at one end respectively in outer and inner tube sheets disposed in a spaced relationship within said shell, characterized in that said shell includes a removable portion (17) enclosing the space between the inner and outer tube sheets (9, 11), said shell portion 17 having a radially outwardly extending flange (21) adjacent the inner tube sheet (9) and a radially inwardly extending flange (19) disposed adjacent the outer tube sheet (11) and connected to an outwardly extending flange (22) of said outer tube sheet (11) said tube sheet flange (22) being disposed within the removable shell portion (17) so as to permit axially sliding removal of said shell portion (17) over said tube sheet flange (22).

2. A heat exchanger as claimed in claim 1, characterized in that said removable shell portion (17) includes expansion means (29) to provide for differential expansion of said shell portion (17) and said inner tube portions (5) extending between said tube sheets.

3. A heat exchanger as claimed in claim 2, characterized in that the expansion means is a bellows (29).

4. A heat exchanger substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. as to enclose the space therebetween and be removably connected thereto. The portion of the shell 17 is flanged at each end. One end has a flange 19 which extends radially inwardly from the portion of the shell 17 and the other end has a flange 21 which extends radially outwardly from the portion of the shell 17. The inwardly extending flange 19 cooperates with an outwardly extending flange 22 that is welded to the head 11 and a gasket 23 to form a seal therebetween. The outwardly extending flange 21 cooperates with an outwardly extending flange 25 and seal ring 27 to form a seal therebetween. The inwardly and outwardly extendingflanges 19 and 21, respectively, allow the shell portion 17 to be removed from the heat exchanger. The shell portion 17 has a bellows 29 or other expansion means disposed therein to allow for differential expansion between the inner wall 5 of the tube 3 and the shell portion 17. The bellows 29 also compensates for any misalignment between the. flanges and assists in aligning the flanges when installing the shell portion 17. The arrangement hereinbefore described provides a removable shell portion 17 for allowing access to the welds between the outer wall 7 and the inner tube sheet 9; provides for differential expansion between the inner wall 5 of the tubes 3 and the shell portion 17; and provides for accommodating misalignment within the flanges 19 and 22 and 21 and 25. WHAT WE CLAIM IS:

1. A heat exchanger comprising a shell, a plurality of double walled tubes supported in said shell and having an inner tube portion disposed within an outer tube portion, said inner and outer tube portions being mounted at one end respectively in outer and inner tube sheets disposed in a spaced relationship within said shell, characterized in that said shell includes a removable portion (17) enclosing the space between the inner and outer tube sheets (9, 11), said shell portion 17 having a radially outwardly extending flange (21) adjacent the inner tube sheet (9) and a radially inwardly extending flange (19) disposed adjacent the outer tube sheet (11) and connected to an outwardly extending flange (22) of said outer tube sheet (11) said tube sheet flange (22) being disposed within the removable shell portion (17) so as to permit axially sliding removal of said shell portion (17) over said tube sheet flange (22).