US3007455A

US3007455A - Vapor generator wall and buckstay arrangement

Info

Publication number: US3007455A
Application number: US706922A
Authority: US
Inventors: Lieb Carl; Russell L Godshalk
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1958-01-03
Filing date: 1958-01-03
Publication date: 1961-11-07
Anticipated expiration: 1978-11-07

Description

Nov, 7, 1961 c. LIEB ETAL 3,007,455

VAPOR GENERATOR WALL AND BUCKS'I'AY ARRANGEMENT Filed Jan. 5, 1958 3 Sheets-Sheet l FIGB INVENTORS Carl Lieb BY Russell L. Godshalk ATTORNEY Nov. 7, 1961 c. LlEB ETAL 3,007,455

VAPOR GENERATOR WALL AND BUCKSTAY ARRANGEMENT Filed Jan. 5, 1958 I5 Sheets-Sheet 2 00 2 i :TN 1 I o I 92 2 3 E3 2 il FIG.6

INVENTORS Carl Lieb BY Russell L. Godsnaik ATTORNEY Nov. 7, 1961 Filed Jan. 3, 1958 c. LIES ET AI. 3,007,455

VAPOR GENERATOR WALL AND BUCKSTAY ARRANGEMENT 5 Sheets-Sheet 3 ATTORNEY nite States 3,097,455 VAPQR GENERATQR WALL AND BUCKSTAY ARRANGEMENT Carl Lieb, Wadsworth, and Russell L. Godshalk, Akron,

Ohio, assigners to The Babcock & Wilcox Company,

New York, N.Y., a corporation of New Jersey Filed Jan. 3, 1958, Ser. No. 706,922 13 Claims. (Cl. 122-6) This invention relates to a wall construction of a vapor generator and more particularly to an improved tubular fluid cooled wall and b-uckstay construction suitable for forming the enclosure or chamber for containing the hot combustion gases at various pressures ranging from below to above atmospheric.

in pressure operated vapor generators the walls defining the gas chamber thereof generally include a row of upright fluid cooled tubes reinforced by laterally supported buckstay assemblies spaced at different elevation along the upright portion of the wall forming tubes. As the row of tubes in the wall are in heat transfer relationship with tie combustion gases and highly heated thereby for maintaining the temperature of the fluid flowing therethrough saturated while the buckstay assemblies in the wall are heated to only room temperature or slightly thereabove, the wall and buckstays are thus subjected to relative rates of thermal linear expansion during the expansionand contraction between the cold and hot position thereof;

Heretofore, it has been customary to secure the buckstays to the vapor generator walls by means of pin and slot connections in order to provide for the relative thermal expansion of the walls and their respective buckstays. While the theoretical aspects of such pin and slot constructions are satisfactory, it has been discovered that such a pin and slot construction is limited in its practical application from a strength standpoint whenever more than one pin is used. This is so because it is oftentimes impossible to have the load of the wall distributed equally on all the pins in excess of one in the thermally stressed position of the wall.

Other known wall and buckstay end connections while satisfactory either required excessive amounts of play or clearances between the parts thereof in order to accommodate the unequal expansion of the relative moving parts or else require field fabrication to very close tolerances which tends to increase the cost thereof.

An object of the instant invention is to provide in a vapor generator an improved wall and buckstay arrangement wherein the load of the wall is uniformly distributed on the buckstay connection under all operating conditions and which arrangement provides for a minimum amount of play or working tolerances between the parts thereof.

Another object is to provide an improved wall and buckstay corner arrangement .in which the shop assembly of parts to the buckstay beam and/or wall tie bars is minimized.

Another object is to provide an improved wall and buckstay construction which can be readily adapted simply and inexpensively to erection conditions which may occur or prevail in the field on a particular installation and thereby facilitate the field erection of a vapor generator embodying the instant invention.

The above objects and advantages of the instant invention are accomplished by connecting a buckstay to an upright Wall of a vapor generator by means of a link which has one of its ends pivotally connected to the wall and has the other end thereof pivotally connected to the buckstay.

A featureof this arrangement resides in the provision of pre-setting of the opposite pivotal connections of the link in the cold position of the wall out of dead center position, the preferred out-of-center pre-set position of the F is pivotal end connections being at least one half the expected swing of the link so that relative expansion of the wall and buckstay from its respective cold to its respective hot position will cause the link to move through its dead center position thus rendering the relative position of the buckstay to the wall substantially the same in both the cold and hot position.

Other features and advantages will be readily apparent when considered in view of the drawings and descriptions thereof:

FIG. 1 is a partial sectional plan view of a fluid cooled combustion chamber incorporating the novel buckstay con nection in accordance with this invention.

H6. 2 is an enlarged detail plan view of the left hand corner viewed in FIG. 1.

FIG. 3 is a section view taken along line 33 of FIG. 1.

P16. 4 is a perspective view of the corner shown in FIG. 2.

FIG. 5 is a diagrammatic showing of the novel link connection in the cold, intermediate and hot positions thereof.

FIG. 6 is a partial sectional plan view of a fluid cooled chamber incorporating a modifie form of the buckstay end connection in accordance with this invention.

FIG. 7 is a vertical end view taken along line '7-7 in FIG. 6.

FIG. 8 is a vertical section view taken along lined-8 in FIG 6.

FIG. 9 is a detail perspective view of the corner tie casting as utilized in the modified form of the invention.

The instant invention constitutes an improved Wall and buckstay arrangement as applied to a vapor generator wall construction of the type disclosed in US. Patent No. 2,703,559 and the like.

As seen in FIGS. 1 to 4, the illustrated Wall construction includes a plurality of upright tubes lit arranged to define walls 11, 12 and 13 of a furnace chamber 14 or the like for containing hot products of combustion gases, the inner I surface of the tubes being exposed in heat transfer relationship to the hot gases contained therein. As it is customary in vapor generators, the upper and lower ends of the tubes It are appropriately connected into a fluid circulation system (not shown). Intermediate the vertical height of the tubes, which may be of considerable extent in some installations, appropriately vertically spaced, hori- Zontally extending tie bars 1'5, 16 and 17 secure the tubes in the respective walls in operative relationship to one another. As shown in FIG. 4, the tie bars of each wall are held in place by weld connections 18, the juxtaposed end portions of the tie bars being welded together at the corners. Thus in effect the tie bars form a band around the periphery of the chamber. The outer area of the walls is then covered with suitable casing and refractory or other insulating material (not shown). 1

In order to prevent any buckling of the tubular wall which may occur under any abnormal operating condi-' tions, reinforcing

buckstays

19, 20 and 21 consisting of relatively large, horizontally disposed, I beams are connected to respective walls 11, 12 and 13 at vertically spaced intervals of the walll As the

buckstays

19, 20 and 21 are supported on the walls exteriorally thereof, they are not subjected to the high temperature of the wall tubes, and at best are only heated to room temperature or slightly thereabove. Consequently, in'opcration the walls 11, 12 and 13 and their respective buckstays are subjected to relative expansion and contraction.

A' plurality of horizontally spaced clips or brackets 22 support each buckstay to its respective wall intermediate the ends thereof, the buckstays terminating adjacent the marginal edges of their respective wall. As seen in FIGS. 1 and 3, each bracket 22 consists "of a C-shaped plate 23 vertically disposed between

mounting plate

24 and 25 by which it is secured to the wall tubes with suitable weld connections. Each bracket includes an upright portion 23A having laterally extending upper and

lower portion

23B, 23C terminating with downwardly and upwardly extending

portions

23D and 23E respectively, to define a slot 26 in the shape of a T rotated 90". As shown, buckstays are supported on the respective walls by positioning the inner flanges thereof in the vertical slot 26 formed in the bracket. As will be hereinafter described the vertical slot 26 is formed sufliciently wide so as to provide for a slight outward movement of the buckstay I beam relative to the wall as the wall and buckstay expand from cold to hot positions.

According to this invention the

buckstays

19, 20 and 21 are connected to the walls 11, 12 and 13 respectively for relative movement thereto by means of novel link connections in which the opposite end portions of the links are pivotally connected to the respective walls and buckstays. While the novel linkage construction may be equally adapted to a wall and buckstay arrangement in which the relative linear expansion thereof occurs in one direction only, by way of example, the description of the instant invention will be directed to the wall 11 and its respective buckstay 19 in which relative expansion thereof occurs from its center point outwardly in opposite directions.

Referring specifically to FIG. 1, each end of buckstay 19 has connected thereto a

plate

28 and 29 projecting beyond the ends thereof and to which one end of

links

30L and 30R respectively are pivotally connected by

pins

31L and 31R. The opposite ends of

links

30L and 30R are pivotally connected to respective corner brackets 32 and 33 by

pins

34L and 34R. As seen in FIG. 4, each

link

30L and 30R may consist of a pair of members A and B disposed above and below the respective plates and corner brackets and are connected thereto by

common pivot pins

31L and 34L. Buckstays 20 and 21 are likewise connected by similarly constructed link means 35 and 36 to their respective walls 12 and 13.

In the cold position of the wall, as illustrated by FIG. 2, it will be noted that the center line of the pins of link connections are preferably oflset. Thus in the cold position the perpendicular distance L between the connecting pins of links is equal to distance between the pins centers times the sine of the angle A. Referring to FIG. 1 it will be seen that as the wall 11 expands from its cold to the hot position, the movement of the corner will be in the general direction as indicated by arrows E, the angular displacement being the resultant movement due to the joint expansion of the adjacent walls 11 and 12 which form the corner. Consequently as the walls will expand at a greater linear rate than their respective buckstays, the links connecting the buckstays to the walls will tend to move in an are so that angle A is increased, and as a result the perpendicular distances between the connecting pins of the links is increased. This increase in the perpendicular distances L between the center lines of the connecting pins of the respective links, will cause the connected buckstays, which are movably mounted relative to the respective walls, to be moved slightly outwardly relative to the wall an amount which is equal to the difference between the sines of the angle A in moving from the cold to hot position. The movement of the buckstay 19 relative wall 11 is shown in FIGS. 3 as indicated by arrows F. This slight movement of the buckstay relative to the wall during expansion will insure that the wall is free to expand at all times relative to the buckstay in a manner so as to avoid any possibility of excessively stressing the inner flanges of the buckstays and binding it to its supporting clip bracket 22, as for example flange 19A of buckstay 19 on the edge 26A of slot 26 as shown in FIG. 3.

While the amount of the predetermined offset between the pivoting pins of the links may be varied, in the preferred and illustrated form the offset is equal to /2 the expected swing of the links as the wall expands from the cold position to the hot position. Referring to FIG. 5, it will be seen that as the wall expands from its cold position A to its hot position C, the link 30, shown as a center line, will move through an intermediate or neutral position B at which position the center lines of the pins are in alignment and angle A equals B. As the link moves from position A to position B angle A increases as do the perpendicular distances L between the pins, the maximum perpendicular distance L occurring when the center line of the pins are aligned in the neutral position B. As the wall expands to its ultimate hot position as viewed in position C of FIG. 5, the link swings through its neutral position and moves to the left thereof as shown. As the link moves to the left of neutral, angle B decreases as do the perpendicular distances between the pins. Since the preferred setting of the links in the cold position is such that the oflset position of the pins is /2 the expected swing of the link, angle A equals angle B and likewise the perpendicular distances L1 is equal to L3 in the extreme positions of A and C. Thus the relative position of the buckstay to the wall in the cold position is the same as it is in the hot position.

FIGS. 6 to 9 are directed to a modified form of the invention. In this embodiment the

walls

111, 112, and 113 defining the furnace chamber 14 or the like comprises a membrane welded wall structure, i.e. each wall includes a row of spaced tubes in which a membrane forming member or weldment 110A connects adjacent tubes to form an imperforate wall section. In this type of wall construction continuous tie bars welded to the tubes, as in the hereinbefore disclosed loose tube wall construction, cannot be utilized. This is due to the fact that the diflerential expansion of the welded membrane wall versus a colder continuous tie bar would cause excessive compression stresses in the membrane or weldment.

The buckstay end connection in accordance with this invention therefore includes a corner tie casting 114 designed to distribute the buckstay end reaction loading over a sufiicient vertical length of membrane, which membrane is the only means for passing the load into the wall construction. As shown the corner tie casting 114 comprises a block having inner arcuate defined

face portions

114A, 114B for embracing the

corner tubes

115, 116 and the

outer face portions

114C, 114D thereof shaped to define a squared corner. A weld secures the casting 114 to corner tubes and 116. Accordingly, one or more corner castings 114 may be superposed at the corner, depending on the vertical load distribution required on the membrane. To the casting or castings 114 is attached an angle plate 117 by means of bolts 118, the angle plate 117 having oversized or slotted holes through which the bolts 118 project to permit vertical differential expansion between the walls and colder angle plate. Attached to the angle plate 117 by welding is a corner bracket or gusset 119 for taking the buckstay end connection linkage 120, which is similar in all respects to that linkage connection hereinbefore described.

A plurality of horizontally spaced clip-like brackets 121 support the intermediate portions of the buckstay 122 to the wall 111. According to this form of the invention each bracket 121 includes a vertically disposed channel member 123 having the toe portions 123A thereof welded to two adjacent tubes. With this construction the channel member 123 provides the desired flexibility to take the diflerential expansion of the wall 111 versus the colder channels 123 over the width of the channels by flexing of the U-shaped channel contours. A vertically disposed plate 124 is welded to the back of each channel and each plate 124 has connected adjacent the upper and lower ends thereof an L-

shape projection

125 and 125A to define a T-shaped slot 126, rotated 90. Received within the slot is the inner flange 122A of the buckstay 122. As hereinbefore described the slot 126 -is sufiiciently wide to provide the necessary clean ances to accommodate the movement of the buckstay relative to the wall during the expansion and contraction thereof as hereinbefore described.

With the foregoing buckstay end constructions the load of the wall is at all times uniformly distributed since it will be transmitted to single pin connections. Further, local structural conditions efiecting the positioning of the buckstay end connection occurring during field erection can be simply and easily compensated for by the

proper positioning plates

23, 29 to the buckstay during erection for any conditions which may occur. Further the novel link connection provides for a minimum amount of play between the wall and buckstay and once assembled no further adjustments are required.

While the instant invention has been disclosed with reference to a particular embodiment thereof, it is to be appreciated that the invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

1. In a vapor generator with an upright wall having marginal edges and a transversely extending buckstay means to support said buckstay in contact therewith, said buckstay having its end portions terminating adjacent the marginal edges of said well, and said wall and buckstay being subjected to relative transverse rates or" linear thermal expansion between the extreme cold and hot positions thereof, the improvement of connecting links securing the terminating end portions of said buckstay to said wall, said links having their opposite ends pivotally connected to said buckstay and said wall, said pivotal end connections of said links being pro-set out of dead center in the cold position of said wall and said buckstay to provide for movement of said links through their dead center position in accommodating the relative transverse linear thermal expansion of said wall and said buckstay.

2. In a vapor generator having two upright walls defining a corner therebetween and a transversely extending buckstay and means to support said buckstay in sliding contact therewith supported on each of said walls and spaced therefrom, said buckstays having juxtaposed end portions adjacent said corner, and said walls and the respective buckstay being subjected to relative thermal expansion in a direction transversely of said wall between a hot and cold position; a corner assembly for connecting the juxtaposed ends of said buckstays to the respective wall comprising a corner bracket connected to said walls, and a link for connecting the junxtaposed end of each of said buckstays to said bracket, the opposite ends of each of said links being pivotally connected to said bracket and respective buckstay, said pivotal end connections of said links being pre-set out of its respective dead center position in the relative cold position of said walls and respective buckstay and movable through its dead center position to resist the loads acting on said walls and to transmit said loads to their respective buckstays.

3. A vapor generator comprising upright walls defining a corner therebetween and each wall having a row of fluid heating tubes therein, a transversely extending tie bar in each of said walls rigidly connected to the tubes thereof and terminating adjacent said corner, a transversely extending buckstay spaced from each of said walls, and means in sliding contact with said buckstay for supporting the same to its respective wall, said buckstays having terminating juxtaposed end portions adjacent said corner, a corner assembly connecting said tiebars and buckstays including a corner bracket, a link connecting the juxtaposed end portions of each buckstay to said bracket, said links having their ends pivotally connected to said bracket and respective buckstay with the pivotal connections of each link being pre-set in the cold position out of dead center said links being movable through their respective dead center position upon relative movement between said walls and their respective buckstays in resisting a portion of the load acting on said walls to maintain said corner tight throughout thermal expansion and contraction thereof and to uniformly transmit said load on said walls to their respec tive buckstays.

4'. A vapor generator comprising upright walls adapted to thermally expand between a cold and hot position defining a corner therebetween and each wall having a row of fluid heating tubes therein, a tie bar in each of said walls rigidly connecting the successive tubes thereof and terminating adjacent said corner, a buckstay extending transversely of said walls, each buckstay being sub jected to a relative rate of thermal expansion of its respective wall, a clip member spacing the respective buckstays from each of said walls and supporting the same thereon, said buckstays being in contact with their respective clip members and having terminating, juxtaposed end portions adjacent said corner, a corner assembly connecting said tie-bars and respective buckstays including a corner bracket, a link connecting the juxtaposed end portionsof each buckstay to said bracket, said links having their ends pivotally connected to said bracket and respective buckstay with the pivotal connections of each link being pre-set in the cold position of said walls and buckstay out of dead center to provide for movement of said links through their dead centered position in accommodating relative linear thermal expansion between the walls and their respective buckstay whereby the latter is moved outwardly relative to its respective wall as the respective links are moved through their dead center position.

5. In combination with two upright tubular membrane walls defining a corner junction therebetween, a buckstay for each well, support means for supporting each buckstay to its respective wall whereby said buckstays are in contact with said support means, and said walls and buckstays are subjected to diiierential rates of thermal expansion and said buckstays having end portions adjacent said junction; theimprovement of corner tie casting connectedito the walls at the corner junction thereof, link means, said link means having one end pivotally connected to the end portions of each buckstay and having its other end pivotally connected to said corner casting, and flexing means connected to each of, said walls spacing the buckstay from each of said walls and supporting the same thereon.

6. In combination, an upright tubular membrane wall, a buckstay, said wall and buckstay being subjected to differential rates of thermal expansion, flexing means connected to said wall supporting said buckstay to said wall in spaced relationship thereto, and link means having opposed end portions pivotally connected to the end portions of said buckstay and to said Wall to accommodate for said differential relative expansion.

7. In combination, an upright tubular membrane wall, a buckstay, said wall and buckstay being subjected to differential rates of thermal expansion, flexing means supporting said buckstay in spaced position relative to said wall, said flexing means including a channel member having toe portions, said toe portions being connected to adjacent tubes of said wall, and an end assembly connecting said buckstay to said Wall, said assembly including a casting connected to said wall, a plate connected to said casting so as to permit relative vertical expansion therebetween, a gusset fixed to said plate, and a link pivotally connected to said buckstay and said gusset to accommodate relative thermal expansion between the wall and buckstay.

8. An upright wall means, a transversely extending buckstay in contact with said wall means to resist the loading imposed on said Wall means, said wall means and buckstay being subjected to relative linear thermal expansion, means for supporting and connecting said buckstay to said wall means, said supporting and conmeeting means including a link means pivotally connected at one end to the wall means and pivotally connected at its other end to said buckstay to provide a connection therebetween to accommodate the relative transverse linear expansion occasioned between said wall means and said buckstay.

9. An upright wall means having a marginal edge portion, a transversely extending buckstay in contact with said wall means for resisting the loading imposed on said wall means, said buckstay having an end portion terminating adjacent said marginal edge portion, said wall means and buckstay being subjected to relative linear thermal expansion, means for supporting and connecting said buckstay on said wall means, said supporting and connecting means including a link means pivotally connected at one end to the wall means and pivotally connected at its other end to said buckstay to provide a connection to accommodate the relative transverse linear expansion occasioned between said wall and said buckstay.

10. A vapor generator comprising an upright wall having marginal edge portions, a clip member connected to said wall intermediate the marginal edges thereof, a buckstay extending transversely of said wall, said clip member supporting said buckstay on said wall in spaced relationship thereto, said buckstay having its end portions terminating adjacent the marginal edges of said wall, said wall and said buckstay being subjected to relative rates of linear thermal expansion between the extreme cold and hot positions thereof, connecting links securing the terminating end portions of said buckstay to said wall, said links having the opposite ends thereof pivotally connected to said buckstay and said wall, said pivotal end connections of said links being preset out of dead center in the cold position of said wall and said buckstay to provide for a movement of said link through its dead center position in accommodating the relative linear thermal expansion between said wall and said buckstay whereby said buckstay is moved slightly outwardly relative to said wall as the said links pass through the dead center position, said outward movement of the buckstay relative to said wall minimizing the stresses imposed by relative thermal expansion between said clip member and said buckstay.

11. In combination with two upright wall means defining a corner therebetween and a transversely extending buckstay on each of said wall means, means for supporting said buckstays in contact therewith on each of said walls for resisting the loading imposed on the respective wall means, each of said wall means and its respective buckstay being subjected to relative thermal expansion, the improvement of a link means connecting each of said buckstays to its respective wall means, said link means having one end pivotally connected to a wall means and having its other end pivotally connected to its respective buckstay to provide a connection to accommodate relative thermal expansion between the wall means and their respective buckstays whereby said link means tend to resist the loading imposed on said wall means and maintain said corner tight during thermal expansion or contraction and to uniformally transmit the loadings of said wall means to their respective buckstays.

12. In combination with two upright tubular membrane wall defining a corner junction therebetween, means for supporting a transversely extending buckstay on each of said wall in sliding contact therewith, wherein said wall and buckstay are subjected to difierential rates of thermal expansion and said buckstay having end portions adjacent to said junction; the improvement of a corner tie castings connected to the wall at the corner junction thereof, and link means having one end pivotally connected to the end portion of each buckstay and having its other end pivotally connected to said corner castings whereby said link means tends to resist the load on said wall to maintain said corner tight during differential expansion and to uniformly transmit the load acting on said wall to their respective buckstays.

13. In combination with two upright tubular membrane walls defining a corner junction therebetween, means supporting a transversely extending buckstay on each of said walls in sliding contact with said means wherein said walls and buckstays are subjected to differential rates of thermal expansion transversely of said walls, and said buckstays having end portions adjacent to said junction; the improvement of a corner tie castings connected to the walls at the corner junction thereof, an angle plate connected to said castings to permit relative vertical movement therebetween, and link means having one end pivotally connected to the end portions of each buckstay and having its other end pivotally connected to said angle plate so that said walls move relative to said buckstays.

References Cited in the file of this patent UNITED STATES PATENTS 1,627,043 Maudsley May 3, 1927 2,267,839 Rehm Dec. 30, 1941 2,655,238 Langvand Oct. 13, 1953 2,700,375 Godshalk et a1. Jan. 25, 1955 2,773,487 Walter et al Dec. 11, 1956 OTHER REFERENCES The Babcock & Wilcox Co.: SteamIts Generation and Use, published by Geo. McKibbon & Son, New York, U.S.A., 37th ed., 1955, pp. 20-7 and 20-14.