US3250319A

US3250319A - Heat exchanger head closure construction

Info

Publication number: US3250319A
Application number: US331739A
Authority: US
Inventors: Vogt Edward
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1963-12-19
Filing date: 1963-12-19
Publication date: 1966-05-10
Anticipated expiration: 1983-05-10
Also published as: GB1074319A

Description

May 10, 1966 E. VOGT 3,250,319

HEAT EXCHANGER HEAD CLOSURE CONSTRUCTION Filed Dec. 1.9, 1965 2 Shegts-Sheet l INVENTOR 2 pw/w0 V06 7' ATTORN EY May 10, 1966 E. VOGT 3,250,319

HEAT EXGHANGER HEAD CLOSURE CONSTRUCTION Filed Dec. 19, 1963 2 Sheets-Sheet 2 as 4 Q .j 92 I F 3 98 l l I X m2 INVENTOR EDWARD Vd? BY MZA M ATTORNEY United States Patent M York Filed Dec. 19, 1963, Ser. No. 331,739 11 Claims. (Cl. 165-81) This invention relates to an all welded pressure vessel for heat exchangers, and in particular, to an all welded channel construction and pass-partition assembly for heat exchangers.

In conventional heat exchangers, it is common practice to provide a channel construction on the head side of the tube sheet consisting of a channel shell, and a closure head secured to the shell by a plurality of bolts. A partition assembly is constructed within the channel for dividing the channel, at least, into inlet and outlet chambers for one of the heat exchange fluids. Because of high design pressures for more recent units, tremendous difiiculties have been encountered in properly sealing the head.

In the heat exchanger to which the present invention relates, it is contemplated that the head, channel shell and tube sheet all will be welded together by suitable girth welds providing an all welded channel construction, but because of design pressures, all Welds must be stressed relieved. The final closing weld will be at the joint between the channel shell and head, requiring that the channel internals be completed, including the welding of partition assemblies within the channel, before local stress relieving of the closing weld.

If the partition plates are welded directly to the pressure channel shell as in conventional units, in the area of the stress relieving zone, the welds between the partition plates and shell are apt to be cracked. The reason for this is that the shell, reaching a much higher temperature (for instance 1100 F.) than the partition plates, has a greater expansion, and the stress created by the expansion difference is capable of tearing the welds loose.

It is contemplated that no manhole opening be provided, so that if there is cracking of a partition plate weld, it would not be known prior to use of the heat exchanger.

Even in normal operation of a heat exchanger, such as a feed water heater, there may be an expansion of the channel shell relative to the partition components, caused by pressures up to 5000 psi. or higher within the channel, from which weld cracks, through stress and strain, could develop.

Accordingly, it is an object of the invention to provide a pass-partition assembly, within an all welded channel construction, which is not subjected to such stress as would develop weld cracks.

In accordance with the invention, there is provided; in a channel construction having a tube sheet channel shell, closure head, and spaced apart inlet and outlet nozzles in the shell; a pass-partition assembly comprising one or more partition plates welded to the tube sheet along an edge or edges intermediate the inlet and outlet nozzles and extending from the tube sheet to an area adjacent the channel shell, the edges of the plates adjacent the shell being free and not welded to the shell. At least one additional curved plate is provided having a curved major surface adapted to seat against or close to the channel 3,250,319 Patented May I0, 1966 shell inner wall, the curved plate being suitably welded to the partition plate free edges and to the channel shell along an edge adjacent the tube sheet (or to the tube sheet itself in accordance with an embodiment of the invention). The curved plate is provided with apertures in sealing communication with the adjacent shell nozzle (inlet or outlet), the partition plates and curved, plate thereby dividing the channel into inlet and outlet chambers in communication with the shell nozzles.

In assembly of the heat exchanger, the channel shell is welded to the tube sheet by a girth weld which is then stress relieved. Following this the pass-partition assembly including the curved plate is welded in place, and the vessel head is Welded to the channel shell by a suitable closing girth weld which then is stress relieved. Since the partition plates are joined to the channel shell, through the curved plate, along a line adjacent to the tube sheet and well removed from the closing girth weld, heat from the latter and the stress relieving thereof does not set up stresses heretofore experienced in such units.

The invention and advantages thereof will become apparent from the following description of the invention, with reference to the accompanying drawings, in which:

FIGURE 1 is a side elevation view of a heat exchanger in accordance with the invention;

FIGURE 2 is a transverse section view on an enlarged scale taken along line 22 of FIG. 1;

FIGURE 3 is a portion of the heat exchanger of FIG. 1, on an enlarged scale, taken along line 3-3 of FIG. 2; and

FIGURE 4 is a portion of a heat exchanger, on an enlarged scale, similar to FIG. 3, of an embodiment in accordance with the invention.

In the embodiment of FIG. 1, the heat exchanger is a cylindrical feed water heater 10 having a heat exchanger shell 12 to which at one end is welded a circular tube sheet 14. A cylindrical channel shell 16 is welded to the head side 18 of the tube sheet by a girth weld 19, and a hemispherical channel head 20 is in turn welded by a closing girth weld 21 to the free edges of the channel shell. Inlet and

outlet nozzles

22 and 24 are provided leading into the channel 25, defined by the tube sheet, shell and head, so that fluid passes through the inlet nozzle into a chamber 26 of the channel, through the tubes of the feed water heater, into outlet chamber 28 of the channel and through the outlet nozzle. accomplished by passage of another fluid through an inlet niJzzle 30 on the tube side 32 of the heat exchanger tube p ate.

FIGS. 2 and 3 show the invention in more detail. In the embodiment of the invention shown the feed water heater is a four-pass design so that fluid entering the inlet nozzle 22 passes into the first chamber 26 (supra) occupying approximately a quarter of the channel, through a first bank 34 of U-shaped tubes into a larger (intermediate) chamber 36 occupying approximately half of the channel, and from the larger chamber, into the outlet chamber 28 (supra) via a second bank 38 of U-tubes. The fluid pressures in the various chambers are approximately equal. I

The pass-partition assembly dividing the channel into the inlet, outlet and intermediate chambers (26, 28, 36) consists of a pair of

cover plates

40 and 42 in the shape of quarter segments arranged when placed together to extend approximately half way across the channel, in a Heat exchange is plane which is approximately parallel to the tube sheet head side 18 and which intersects the channel shell 16 in the area of the closing head to channel girth weld 21. A flat rectangular partition plate 46 extends along the center line of the channel, perpendicular to the tube sheet, dividing the channel into the chamber 36 on one side, and into the

chambers

26 and 28 on the other side, the upper edge 47 of the partition plate being adjacent (and welded to) aligned straight edges 48 and 50 of the cover plates. The partition plate 46 along the opposite (bottom) longitudinal edge 52 is welded to the tube sheet head side 18.

' A second partition plate 54 extends between the tube sheet 18 and adjacent

straight edges

56 and 58 of the cover plates, having on one side the inlet chamber 26 and on the other side the outlet chamber 28. This partition plate is welded to these adjacent edges, to the tube sheet head side 18, along the bottom edge 60 (FIG. 3), and also to the first partition plate along a side edge 61. Extending between the free opposite ends of the rectangular partition plate 46 is a curved semi-cylindrical shaped plate 62 disposed adjacent the semicircular curved inner surface of the channel shell. The curved plate is welded at its ends (by welds 64 and 66) to the free opposite ends of the partition plate 46, and also is welded, along the free edge removed from the tube sheet (weld 67) to the

cover plates

40 and 42. Along the opposite edge adjacent the tube sheet, the curved plate 62 is welded (weld 69) to the channel shell, close to the tube plate and well removed from the shell to head closing girth weld 21. Apertures 68 and 70 are formed in the curved plate aligned with the

channel'nozzles

22 and 24, and in the area of the curved plate around the apertures, welds 72 and 74 are made to seal the inlet and

outlet chambers

26 and 28 from the remainder of the channel. A further weld 75, between second partition plate 54 and curved plate 62 completes the pass partition assembly.

In the pass-partition assembly, stops 76 are disposed on the curved sheet and pass-partition plates to facilitate construction of the assembly. The cover plates are seated on the stops and are then Welded into place.

Following construction of the pass-partition assembly within the channel shell, the channel head 20 is welded to the channel shell by the girth weld 21, the final closing weld of the unit. Because operating pressures in the unit on the head side of the tube sheet may be in the range of 3000 to 5000 p.s.i., or more, the final girth or closing weld must be stressed relieved at a temperature of about 1100 F. In accordance with the invention, by

separating the cover plates and partition plates (items 40,

' within the channel, the channel shell is permitted to expand independently of the pass-partition assembly. In this respect, the pressures on opposite sides of the partition plates and cover plate are substantially equal taking into consideration pressure drop through the heat exchanger tubes.

It should be noted also in this respect, that the curved partition plate 62 can be a very thin diaphragm-like member since the pressures on opposite sides of the plate also will be substantially equal and little deformation of the plate will occur.

Although the invention has been described with reference to a four-pass design, it can also be used with a twopass arrangement in which the pass-partition assembly would be formed of a semi-circular cover plate segment covering approximately half of the channel, only one end partition plate and a semi-cylindrical curved plate dividing the channel into the inlet and outlet chambers only. The same principals mentioned above with respect to welding of the assembly within the channel would be practiced.

FIG. 4, illustrates the principles of the invention applied to a channel having a spherical configuration. In the example of FIG. 4, a hemispherical head 80 is welded to a spherical annular shoulder 82, the latter protruding outwardly from a peripheral lip 84 on the sides of the tube sheet 86. 'This type of channel is described in U.S. patent application, Serial No. 327,027, filed November 29, 1963, inventor Solomon C. Hollister, assigned to the assignee of this application.

As with the channel of FIGS. 1-3, if the partition plate is Welded between the tube sheet and channel head, expansion of the latter could result in excessive stress on the partition plate and cracking of welds for the latter.

Accordingly, it is proposed to weld the partition plate 88 along one edge 90 to the tube sheet 86, and along the opposing edge 92 to a curved plate 94 which conforms to and is disposed next tothe inside surface of the head 80. The plate 94 at its edge 96, opposite to that joined to the partition plate edge 90, is welded to the tube sheet, along the peripheral edge of the tube sheet. It is apparent that expansion of the head relative to the tube sheet will not result in excessive stress on the partition plate. I

The partition plate assembly is provided with a tube of pipe 98 communicating the chamber 100 with head nozzle 102. The curved plate 94 is capable of slight deformation to accommodate for expansion of the head 80.

Also, although the invention has been described with respect to a particular shaped channel, it is apparent that principles of the invention can be applied to channels provided with a spherical configuration. Other configurations are applicable to the invention, and within the spirit and scope of the invention as set forth in the following claims.

What is claimed is:

1. An all welded head closure construction for heat exchangers comprising;

a tube sheet having a head side;

an annular-metal channel shell welded to said tube sheet;

a dome shaped head welded to the free end of said channel shell, said shell and head being adapted to withstand high pressures;

an all welded pass-partition assembly within saidchannel comprising a partition plate means welded to the tube sheet and extending partially across the channel having edges adjacent but not connected to the shell or head inner wall in the area of the head to shell Weld, and curved plate means adjacent the shell inner wall extending between said adjacent edges welded thereto and an area of the channel shell adjacent the tube sheet head side Welded thereto and removed from the head to shell weld, said partition plate means and curved plate means dividing the channel into inlet and outlet chambers.

2. An all welded head closure construction in accordance with claim 1 wherein said partition plate means includes a first flat cover plate in the shape of a semicircular segment disposed parallel to the tubesheet head side, a second flat plate in the shape of a rectangle extending at right angles to and being welded to the tubesheet head side and thesemicircular cover plate, the curved plate being welded to opposed ends of second partition plate and to the circular edge of the cover plate.

3. An all welded head closure construction in accordance with claim 2 wherein the annular metal channel shell is provided with nozzle openings for-the inlet and outlet of fluid to the channel, the curved plate being provided with at least one aperture in the area of at least one of the nozzles and being welded to the inner surface of the metal shell in the area around the nozzle.

4. An all welded head closure construction for heat exchangers according to claim 3 including a third partition plate extending at right angles to said second IG- tangular plate between and welded to the second plate and the curved plate, the partition assembly dividing the channel into inlet and outlet chambers of approximately equal volume and an intermediate chamber, the inlet and outlet chambers being connected to the inter mediate chamber by banks of U-shaped tubes, said construction further including inlet and outlet nozzles in communication with the inlet and outlet chambers, the curved plate being welded to the inner surface of the metal shell in the areas around the nozzles.

5. A pass-partition assembly for a heat exchanger, which includes a tube sheet having a head side and a shell side; a channel construction comprising an annular metal shell depending from the tube sheet head side, a dome shaped channel head welded by a girth weld to the free end of said channel shell; the assembly comprising;

a partition plate means welded along one edge to the tube sheet head side and extending across the channel having free edges adjacent the inner wall of the channel construction in the area of the head to shell weld;

curved plate means having a major surface contiguous with the channel inner wall, said curved plate means extending between and being welded to the partition plate free edges and an area of the channel shell removed from the head to shell weld;

the partition plate means and curved plate means defining inlet and outlet chambers within the channel.

6. A channel construction comprising a tube sheet,

a cylindrical channel shell welded by a girth weld to the tube sheet,

a closure head welded to the channel shell by a closing girth weld, the girth welds being stress relieved,

spaced inlet and outlet nozzles in the channel shell,

a pass partition assembly arranged to be constructed within the channel prior to Welding and stress relieving the closing girth weld, the assembly comprising,

at least one partition plate means welded to the tube sheet along a first edge and extending between the inlet and outlet nozzles, the partition plate means having a second free edge opposing the first edge and being adjacent but not connected to the channel shell in the area of the closing girth weld,

at least one curved plate having a curved major surface contiguous with the inner wall of the channel shell, the curved plate being welded along a first edge to the partition plate free edge, to the channel shell in an area sufficiently removed from the closing girth weld to avoid stresses by difierential expansion of the channel shell and partition assembly, to the partition plate means along remaining free edges, and to the channel shell in the area around at least one of the inlet and outlet nozzles,

the partition assembly defining inlet and outlet chambers in the channel,

the curved plate having at least one aperture for communication of the nozzles with the inlet and outlet chambers.

7. A construction according to claim 6 wherein the partition plate means comprises at least one partition plate extending approximately vertically from the tube sheet head side, and at least one cover plate extending approximately parallel to the tube sheet head side, the vertical plate and cover plate being welded together.

8. An all welded head closure construction for heat exchangers comprising;

a tube sheet head side; a cylindrical metal channel member welded at one end to said tube sheet head side; a dome-shaped channel head welded to the free ends of said member; a pass partition assembly encompassed by said channel member comprising a partition cover plate extending at least partially across the channel in a plane approximately parallel to said tube sheet head side and intersecting said channel member in the area of the head to member weld,

at least one pass partition plate extending vertically between said tube sheet head side and said cover plate dividing said channel with the cover plate at least into inlet and outlet chambers,

curved plate means adjacent the surface of said channel member welded to said member along a bottom edge adjacent to said tube sheet head side and welded to said partition cover plate along an upper edge, the welded edges being approximately parallel,

the partition plate and curved plate each having opposed ends adjacent to an opposed end of the other extending in an approximately vertical direction from the sheet, the partition plate and curved plate being welded together along said adjacent edges to seal the inlet and outlet chambers at least from each other.

9. An all welded head closure construction for a four pass heat exchanger comprising;

a tube sheet head side;

a cylindrical metal channel member welded at one end to said tube sheet head side;

a dome-shaped channel head welded to the free end of said member;

a pass partition assembly encompassed by said channel member comprising a pair of flat adjacent cover plates in the shape of quarter segments arranged with straight edges of each aligned so as to extend halfway across the channel in a plane which is approximately parallel to the tube sheet head side and which intersects the channel member in the area of the head to member weld,

fiat rectangular partition plate extending along the center line of the channel welded along one edge to the aligned edges of the partition cover plates and along an opposed edge to the tube sheet head side, the partition plate extending vertically from the tube sheet, a second partition plate extending in a plane perpendicular to the first mentioned partition plate and between said cover plates and the tube sheet in a plane vertical to the latter, the second plate being welded to the abutting edges of the cover plates and to the tube sheet, a curved plate means having a major surface adjacent the surface of the channel member welded to the member along a bottom edge near the tube sheet head side and welded to the partitioh cover plates along an upper edge approximately parallel to the lower edge, the curved plate further being welded to the partition plates to define inlet and outlet chambers and an intermediate chamber.

10. An all welded head closure construction for heat exchangers comprising;

a tube sheet having a head side;

a hemispherical channel head;

spaced apart inlet and outlet nozzles in the channel head;

means joining the channel head to the tube sheet on the head side thereof;

a pass-partition assembly within the channel defined by the tube sheet and channel head comprising a partition plate means extending partially across the channel between said inlet and outlet nozzles having a free edge and one edge welded to the tube sheet head side,

a curved plate conforming somewhat to the inside sur face of the head and being disposed near the head inside surface also having a free edge and one edge welded to the tube sheet, the free edges of the partition plate and curved plate being welded together, the partition plate and curved plate defining with the tube sheet an enclosed chamber;

7 8 means communicating one of said nozzles with the one additional edge welded to said channel inner surchamber. 1 face in the area of the tube sheet head side todefine 11. A pass partition assembly for a heat exchanger, with the partition plate means an enclosed pass with- Which includes a tube sheet having a head side and a in the channel. shell side; a channel welded to said tube sheet head side, 5 the channel defining with the tube sheet an all-welded References Cited y the Examiner head closure construction, the inside surface of the chan- UNITED STATES PATENTS nel and tube sheet head side defining the channel inner 2,060,078 11/1936 Hobbs X surface, the assembly comprlsmg 2919 906 1/1960 Hai ht 165 72 a partition plate means Welded along one edge to the 10 3014702 12/1961 tube sheet head side and extending across the channel having free edges adjacent the inside surface of FOREIGN PATENTS the channel; 946,944 12/1948 France.

curved plate means having a major surface contiguous with said channel inside surface, said curved plate 15 ROBERT A, OLEARY, Primary Examiner. means having edges extending between and welded to said partition plate means free edges and at least KENNETH SPRAGUE m

Claims

1. AN ALL WELDED HEAD CLOSURE CONSTRUCTION FOR HEAT EXCHANGERS COMPRISING; A TUBE SHEET HAVING A HEAD SIDE; AN ANNULAR METAL CHANNEL SHELL WELDED TO SAID TUBE SHEET; A DOME SHAPED HEAD WELDED TO THE FREE END OF SAID CHANNEL SHELL, SAID SHELL AND HEAD BEING ADAPTED TO WITHSTAND HIGH PRESSURES; AN ALL WELDED PASS-PARTITION ASSEMLBY WITHIN SAID CHANNEL COMPRISING A PARTITION PLATE MEANS WELDED TO THE TUBE SHEET AND EXTENDING PARTIALLY ACROSS THE CHANNEL HAVING EDGES ADJACENT BUT NOT CONNECTED TO THE SHELL OF HEAD INNER WALL IN THE AREA OF THE HEAD TO SHELL WELD, AND CURVED PLATE MEANS ADJACENT THE