US3793991A - Expansion plate - Google Patents

Abstract

An expansion plate or sheet comprises a plurality of panels in sealed side-by-side relation, each panel including a sheet, or sheets, which extend continuously substantially the full distance between two adjacent walls for connection in air-tight relationship therewith and most of said panels include at least one elongated depression therein which extends much of the distance between the two adjacent walls.

Description

United States Patent [191 Round et al.

[ Feb. 26, 1974 EXPANSION PLATE Inventors: Byron Joseph Round, Simsbury;

Eizens Abolins, Windsor, both of Conn.

Combustion Engineering, Inc., Windsor, Conn,

Filed: Dec. 26, 1972 Appl. No.: 318,332

Assignee:

US. Cl 122/6 A, 122/494, 122/510 Int. Cl. F22b 37/24 Field of Search 122/6 A, 235 A, 235 G, 494,

References Cited UNITED STATES PATENTS 5/1945 Foresman 122/235 3,310,038 3/l967 Kuchelbacher 122/494 3,364,905 l/1968 Jordan 122/494 3,402,700 9/1968 Brunner 122/6 3,407,788 10/1968 Hagmann.... 122/6 3,592,171 7/1971 Bernstein 122/494 Primary Examiner-Kenneth W. Sprague Attorney, Agent, or FirmStephen A. Schneeberger [5 7] ABSTRACT An expansion plate or sheet comprises a plurality of panels in sealed side-by-side relation, each panel including a sheet, or sheets, which extend continuously substantially the full distance between two adjacent walls for connection in airtight relationship therewith and most of said panels include at least one elongated depression therein which extends much of the distance between the two adjacent walls.

6 Claims, 6 Drawing Figures EXPANSION PLATE BACKGROUND OF THE DISCLOSURE This invention relates to an expansion joint and more particularly to an air-tight connection between two adjacent members subject to different operating temperatures and hence to different changes in physical dimensions.

A problem has existed in providing a fluid-tight connection between two adjacent members subject to different operating temperatures and hence to different amounts of expansion, particularly where it is impractical to use slip joints or packings. This problem is particularly acute in large vapor generators in which there may be temperature differences of several hundred degrees F. between adjacent surfaces, such as between a steam header or fluid cooled ring pipe or header and an adjacent uncooled ash hopper through which combustion gases are directed. Because of the large size of the steam generators now being considered, and the high temperatures at which they operate, the differences in expansion between adjacent surfaces may cause one surface to lengthen appreciably more than the adjacent surface or element.

One example of an expansion plate developed to accommodate this problem where air-tight connections are required is disclosed In U. S. Pat. No. 3,343,327 to Konrad S. Svendsen for Expansion Plate. In the Svendsen patent an expansion plate was provided having one or more panels, some of which comprised a plurality of adjoining cup-shaped members in side-by-side welded relation. The cups of these panels are deformed by opposed relative forces on opposite longitudinal edges of the panel of which they are a part. Deformation of the cups allows an overall deformation of the panel to accommodate the force couple resulting from said opposed forces and to allow relative longitudinal movement of the opposed edges.

While the multiple cup type of panel is generally satisfactory as an expansion plate, it does have several drawbacks. The many adjacent cups in a panel are formed in a rectangular grid and require welding to join them to one another in gas-tight relationship. In some instances the cups might be formed by welding wall portions to one another. Typically a 3 foot by 4 foot (or 3 inch X 4 inch) panel might have to 50 or more cups requiring six to eight weld seams transverse to the longitudinal extent of the panel and two to six or more weld seams extending longitudinally of the panel. In order to obtain panels having a sufficient number of cups to allow the required deformation of the panel, it will be evident that considerable time consuming and expensive welding is required, some under difficult manufacturing conditions.

Further, each weld seam exhibits discontinuities caused by projections, irregularities and flaws in the formation of the weld. Such discontinuities, as is well known, create weak spots at which cracks may originate. These cracks may become sufficiently large to allow gas leakage. Such cracks may originate from thermal or pressure stressing of the region, as might normally occur during operating cycles. While such discontinuities might be reduced in number or removed as by great care in welding or through subsequent machining, these operations are time consuming and expensive.

Other expansion joints have employed bellows-like members; however, these bellows have typically included a large number of weld seams in their formation and particularly in regions thereof which are difficult to machine, thereby allowing the unwanted discontinuities.

SUMMARY OF THE INVENTION According to the present invention, an expansion plate or sheet is provided which comprises a plurality of panels in sealed side-by-side relation, each panel including sheets which extend continuously substantially the full distance between two adjacent walls for con nection in airtight relationship therewith and most of said panels including at least one elongated depression therein which extends much of the distance between the two adjacent walls.

The elongated depression in each panel is formed by a die-stamp or drawing process which results in a smooth continuous surface substantially devoid of discontinuities. Each depression is preferably several times longer than wide and more than 1% times as deep as wide along most of its length. This configuration readily permits deformation of the panels through shear deformation of the depressions when opposite longitudinal forces are applied to the opposite longitudinal edges of the panels, as through different expansions of the adjacent wall edges. The expansion plate formed by the above-described panels includes weld seams only extending parallel the depressions, and accordingly, transverse to the edges of the adjacent walls to which the panels are joined.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic outline of a steam generator and furnace in which this invention finds particular application.

FIG. 2 is a detailed cross-section on line 22 of FIG. 3 of the plate and panel connection and geometry according to the invention.

FIG. 3 is a side view of an assembled wall comprising panels of plates connecting a steam header and an ash hopper of a steam generator.

FIG. 4 is a cross-section of a panel depression taken along line 4-4 of FIG. 3.

FIG. 5 is an enlarged side view somewhat exaggerated of a corner of a distorted wall.

FIG. 6 is an enlarged top view of the corner shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a typical steam generator is diagrammatically illustrated in FIG. 1 to show one application of the invention and comprises a furnace 10 having a combustion chamber 12 defined by parallel, vertically extended welded together tubes 16 forming the furnace walls and a portion of the gas pass 36 and adapted to have water forced therethrough for conversion into steam. The water is fed by feedwater pumping, not shown, into headers such as 18, 20 and 22 and forced upward through the tubes 16 into a header 24 and thence into a steam drum 26 in a well known manner. Steam is separated from the water in the drum 26 and is lead through the pipes 28 to the header 30 and tubes 32 to a header 34 from which it may be fed to additional superheaters, not shown, and

thence to the point of consumption, not shown. It will be noted that the gases from the combustion chamber 12 pass upward and then laterally through a horizontal gas pass indicated generally at 36 thence through a downwardly directed gas pass 38 into a soot or ash hopper 40 and out through a duct 42 to the usual stack.

It is necessary that the gas pass andin fact the entire furnace from combustion chamber to stack be maintained as an air-tight duct particularly where the furnace and combustion chamber is operated at an elevated pressure, or pressurized. One such point along the gas pass that must be kept air-tight is the connection between the steam or water header 34 and the walls of the ash hopper 40. The header 34 is steam or water cooled while the walls of the ash hopper are subjected to the full temperature of the combustion gases passing through the-hopper on the way to the stack and hence are raised to a temperature somewhat higher than the steam or water cooled header 34. The difference in temperatures at the two adjacent surfaces of header 34 and ash hopper 40 subject them each to different amounts of expansion.

In furnace construction itis usual to suspend the entire furnace including all of the walls from overhead as by beams 44 and rods 46 supporting the header and the tubes connected therewith. As will be explained in more detail later, the walls of the ash hopper 40 are suspended from the header 34 and being subjected to a higher operating temperature than the header 34 will expand to make the perimeter of the ash hopper considerably greater than the perimeter of the header 34. Applicants expansion plate is used to connect and form an air-tight connection between the header 34 and the walls of the hopper 40 and is shown somewhat schematically and diagrammatically at 48 in FIG. 1.

In order to more fully explain the invention, the details of the structure at 48 connecting the header 34 with the walls of the hopper 40 are illustrated and explained. This explanation will make it adequately clear how this construction can be used to connect these and other similar adjacent surfaces.

FIG. 2 shows a section of the header 34 and wall 52 of the hopper 40. The wall 52 is secured in any suitable manner as by welding to a structural member, such as channel iron 54 which is suspended from the header 34 by straps 56 and pin joints 58. The upper edge of wall 52, which might also be a non-integral extension of hopper 40, is received between and forms a slip joint with a pair of spaced plates 60 secured in any suitable manner as by welding to the header 34. A plate, indicated generally at 62, and including the subject of this invention is positioned outside of the hopper 40 and has one longitudinal edge secured in any suitable manner as by welding to the header 34 and the opposite longitudinal edge secured in any suitable manner, preferablyby welding, to the channel 54 supporting the hopper walls.

The walls formed by plate 62 extend around the four sides of rectangular hopper 40 and forms an air-tight connection between the hopper and the header 34. It will be appreciated that the tubes leading vertically upward from the header 34 are welded together to form the duct defining the gas pass 38 or other suitable means are provided to define that gas pass terminating in the header 34.

FIG. 3 is a side view of one-half of the ash hopper which may be 70 or more feet across and shows portions of one-half of the plate 62 extending along that side, with the center line of the plate shown at the extreme left hand edge of the figure being taken as a portion of the hopper that has no relative longitudinal movement with respect to the header 34 so that the hopper is substantially fixed longitudinally of the header 34 at this point but expands so as to move longitudinally outward of the header 34 at the comer of the hopper. Hence, all four corners of the hopper will move outwardly with respect to the rectangular header 34.

It will be noted that the plate 62 is made up of a plurality of individual panels such as 64, 65, 66 and 68 and 69 among others. These panels are arranged in a row with their adjacent vertically extending edges secured together and together form the plate 62. As there is substantially no relative movement of the hopper wall longitudinally of the pipe forming the header 34 adjacent the center line of the hopper side wall, the panel 64 is a plain rigid sheet having one edge welded to the header 34 and the other edge welded to the channel iron 54.

As was described in the earlier-mentioned Svendsen patent, relative longitudinal movement of the plate 62 increases away from the center line of the hopper side wall as one moves toward the end of the plate 62. The Svendsen patent accommodated thisrelative longitudinal movement by forming the various panels which make up plate 62 of deformable sheets having many cup-like depressions therein which increase in number the more distant the panel is from'the center line of the hopper'side wall. In the present expansion plate the panels are also designed to accommodate the increasing relative longitudinal movement; however, these panels preferably, though not necessarily, are uniform with the exception of panel 64 and more importantly are designed such that they greatly reduce the opportunity for discontinuities in their structure, as for instance from irregular welds. Each of the present panels beginning with 65 and continuing on through panels 68 and 69 are constructed to permit relative movement of the upper and lower edges of plate 62 by allowing the sheet of the respective panel to torsionally distort under shear forces to accommodate such relative movement.

A partial view of the torsionally distorted sheet with the distortion somewhat exaggerated to more clearly illustrate the same is shown in FIG. 5. The relative longitudinal movement of header 34 and channel 54 produces a force longitudinally of one edge of the plate 62 and a parallel force in the opposite direction longitudinally of the opposite edge of the plate 62. The spacedapart non-intersecting forces produce a force couple which is absorbed by shear deformation of the sheets of the several panels 65 through 71 which amounts to shear deformation of the plate 62.

- As earlier mentioned, panel 64 is a plain rigid sheet.

The remaining panels, moving or looking toward a corner, and including panels 65, 66, 68 and 69 each are comprised of a rectangular sheet 72 of metal, such as 12 gauge steel. Typically, a sheet 72 will be about 8 inches in width longitudinally of plate 62 and some 20 to 36 inches in length transversely of the plate. Each sheet 72 is intended to distort with the relative opposing forces applied to the opposite longitudinal edges thereof during expansion of header 34 and hopper wall 52.

Each sheet 72 of the panels 65-69 includes an elongated trough-like depression 74 therein which accommodates the shear forces at the opposite longitudinal edges of the sheet by allowing shear deformation of the sheet. Depression 74 extends preferably nearly the entire vertical, or transverse, exteng of a sheet 72 along the mid-line thereof and may be some 18 to 36 inches in length. The greatest width of depression 74 occurs at its lip and is on the order of 1% to 2% inches as indicated by w in FIG. 4. This width is maintained for most of the length of depression 74. The depth of depression 74 indicated as d in FIG. 4 is about 4 to 5 inches over most of the length of the depression. The width and depth of depression 74 are both decreased in a smooth and continuous manner over the final several inches at each end thereof to close the ends of the depression. These end closures appear somewhat like a bulletnose or rather half of a bullet-nose as divided by a plane on the axis of the bullet.

Depression 74 is formed in sheet 72 by means of a multi-stage drawing process. Several dies of increasing depth and slightly increasing width and length are employed. The sheet 72 is placed sequentially in each die and depression 74 is partially drawn on each, with an intermediate heat treatment of the sheet occurring between successive drawing operations, as required. Such heat treatment for stress relief would normally be performed on stainless steel and not on carbon steel. The dies are shaped such that the final resulting depression 74 is somewhat wider at its lip or base than at the peak and, as mentioned earlier, shallows at its ends. The contour of depression 74, both internally and externally, is smooth and continuous, employing rounded surfaces where transitions in slope or direction are required. The thickness of the walls of a depression 74 of the size and geometry described hereinbefore will typically be at least 65 percent or more of the original thickness of sheet 72, providing adequate strength to the depression. Any distortion of the edges of sheet 72 due to the stamping operation is corrected by trimming and sizing the edges to provide the desired rectilinear form and size.

The above-described forming process and the resulting sheet 72 with depression 74 provide a member which is capable of shear distortion to accommodate the described growths but which is free of welds and the discontinuities often engendered thereby;

In order to form expansion plate 62, a series of panels 65, 66, etc., are joined to one another in side-by-side air-tight relationship as by welds 76. Welds 76 occur between and along transversely extending edges of adjacent abutting sheets 72. Welds 76 are thus transverse to the longitudinal edges of the panels and expansion plate 62. Welds 76 comprise substantially the only major welds in sheet 62 except at or near the transverse extremes thereof. Panel 65 will be joined with rigid panel 64 by a similar transversely extending seam weld.

" Panels 65, 66, etc., may each be installed separately in the field; however, it has generally proven more efficient and economical to weldingly join several panels in side-by-side relationship at the time of manufacture to form major panels which may be to feet in longitudinal extent. The major panels are in turn joined to one another in the field by field welds 78 along transversely extending adjacent edges of the major panels.

The longitudinally extending upper edge portion of each sheet 72 and accordingly of each panel 64, 65, 66 etc., is welded in air-tight relation to a strip 80 which extends longitudinally along header 34 and is welded thereto in air-tight relation'therewith. Each sheet 72 is mounted such that the depressions 74 extend outward from gas pass 38. The opposite edge portion of each sheet 72 is secured in air-tight relationship as by welding to a double bent, or open U-shaped, metal strip 82 which in turn is secured as by welding with channel 54 to form an air-tight connection therebetween. Double bent strip 82 allows a limited degree of vertical, or transverse, movement of the sheets 72 relative to ash hopper 40 if such is needed. Strip 82 may be considered either as a portion of each panel 64, 65, 66 etc., as joined thereto during manufacturing or as a portion of ash hopper 40 which aids in joining the panels thereto during field installation. Preferably, strip 82 will be joined to the lower edge of the several sheets 72 which comprise a major panel at the time of manufacture.

In order to prevent the flexible sheets 72 forming the panels 65, 66, etc., from bulging from the pressure in gas pass 38, a channel iron 84 or another type such structural member is supported against the outside of plate 62. Channel irons 84 are positioned at various locations along plate 62 intermediate various adjacent pairs of depressions 74 and are retained by means of a clip 86 welded to strip at one end of the channel 84 and a clip 88 welded to the channel 54 at the other end of channel 84.

Where expansion plate 62 encounters a corner as in FIG. 6 it is comprised of several panels such as 70, 71, 73 and 75 which are comprised of sheets 72 and depressions 74 identical to those in panel 65 with the exception that their sheets 72 are longitudinally curved, rather than flat, such that the several sheets in side-byside welded relation complete a 90 bend. Typically, the panels containing these curved sheets, for instance 70, 71, 73 and 75, are weldingly joined side-by-side at manufacture to form a major panel and are field welded to adjacent panels in the field. A corner seal plate 90 may be used at each comer to sealingly connect as by welding the upper longitudinal edges of panels 70, 71, 73 and 75 with the header 34 to insure an air-tight seal along the entirety of plate 62.

. FIGS. 5 and 6 show, somewhat exaggerated, how the flexible plate distorts to accommodate the difference in longitudinal expansion in the elements it connects. The longitudinal movement of the expansion is absorbed by the longitudinal movement of one edge of the flexible sheet relative to the other under the shear forces imposed by the expansion. The depressions or troughs 74 skew somewhat from a vertical orientation to one in which that portion nearest header 34 moves relatively longitudinally toward the center line of hopper 52 and the portion nearest hopper 40 moves relatively longitudinally toward the corner. At the corners, the portion of depression 74 nearest header 34 moves relatively inward toward the center line of gas pass 38 and the other end moves relatively outward therefrom. Little or no longitudinal skewing occurs right at the corners, but the longitudinal shear forces developed along the side walls causes shear distortion of the panel which increases in magnitude near the corners. While the number or frequency of occurrence of depressions 74 might be decreased nearer the center line of hopper wall 52, it has been found desirable by experimentation to use a uniform panel member with a single depression for every one of the panels from 65 outward to the comer.

The shear forces which skew depressions 74 accordingly distort or skew the panels themselves. This distortion of the depressions accommodates or allows this deformation of the panels to occur without damage to the panels. Additional torsional distortion of depressions 74 about an axis running the length thereof has also been noted. The relatively great depth-to-width ratio of the depressions is felt to aid in the deformation process, particularly along the sides of plate 62 near the corner where the opposed longitudinal forces are greatest.

While for the purpose of illustration and explanation the connecting plate has been described in detail as the connection between a steam header and an ash hopper subject to different operating temperatures and hence to different amounts of expansion, it will be understood that the invention is not limited to such structure, however, and that this invention may be used as a means for connecting other elements subject to limited relative movement particularly where that relative movement is occasioned by temperature differences and it is desired to have the connection form an air-tight connection between the two elements.

What is claimed is:

l. Means forming an air-tight connection between two adjacent sections of a gas pass wall, which sections have different relative operating temperatures comprising an elongated imperforate plate, edge welded airtight to and connecting said sections and forming a portion of said wall, said plate comprising a series of transversely extending panels each welded in side-by-side arrangement, the panel at a selected longitudinal portion of said plate comprising a substantially undistortable plain sheet and the remaining panels intermediate said selected portion and one end of said plate each comprising a continuous sheet extending substantially the entire transverse extent of said panel and having a depression therein extending most of the transverse extent thereof, whereby to absorb a force couple on said plate by shear deformation of said depressioncontaining panels.

2. An air-tight connection connecting adjacent walls of two abutting ducts, said ducts having adjacent edges subject to relative movement longitudinally of said edges and producing a change in the relative perimeter of said abutting ducts, said connection comprises an imperforate plate extending continuously substantially the entire distance between said abutting ducts and ineluding elongated depressions therein extending substantially the full extent thereof transverse to the adjacent edges of said abutting ducts, means connecting one edge of said plate in an air-tight manner with one wall of one duct to form an integral extension of said duct wall and to apply forces in one direction longitudinally of one edge, and means connecting the opposite edge of said plate in an air-tight manner with the adjacent wall of the other duct to form an integral extension of said adjacent wall and to apply forces in the opposite direction lengthwise of said opposite edge, said plate being distortable by said forces and the relative longitudinal movement of said adjacent edges, said connection accommodating said relative movements of said adjacent duct walls by shear distortion of said plate.

3. Means as claimed in claim 2 wherein said imperforate plate includes a plurality of panels, each panel extending continuously substantially entirely between said abutting ducts and joined in air-tight side-by-side relationship by weld seams extending only substantially parallel said elongated depressions transversely of the adjacent edges of said abutting ducts and each said panel includes a said elongated depression therein.

4. A torsionally distortable panel for connecting two adjacent members, which members are subject to movement longitudinally of the panel edge, said panel including a continuous sheet extending transversely substantially the entire transverse extent of said panel and having an elongated depression therein extending most of the transverse extent of said sheet, first means for connecting one edge of said panel with one of said adjacent members and second means for connecting the opposite edge of said panel with the other said adjacent member, said edge connecting means adapted to transmit the relative longitudinal movement of said members, and the resulting force couple, longitudinally to the opposite edges of said sheet, said sheet being deformable by said transmitted relative longitudinal movement, cause a skewing and torsional bending of said depression.

5. Means as claimed in claim 4 wherein the depth of said depression over most of its length is at least 1.5 times its width thereat.

'6. Means as claimed in claim 5 wherein the length of a said depression is more than twice the width of said depression.

Claims (6)

1. Means forming an air-tight connection between two adjacent sections of a gas pass wall, which sections have different relative operating temperatures comprising an elongated imperforate plate, edge welded air-tight to and connecting said sections and forming a portion of said wall, said plate comprising a series of transversely extending panels each welded in side-by-side arrangement, the panel at a selected longitudinal portion of said plate comprising a substantially undistortable plain sheet and the remaining panels intermediate said selected portion and one end of said plate each comprising a continuous sheet extending substantially the entire transverse extent of said panel and having a depression therein extending most of the transverse extent thereof, whereby to absorb a force couple on said plate by shear deformation of said depression-containing panels.

2. An air-tight connection connecting adjacent walls of two abutting ducts, said ducts having adjacent edges subject to relative movement longitudinally of said edges and producing a change in the relative perimeter of said abutting ducts, said connection comprises an imperforate plate extending continuously substantially the entire distance between said abutting ducts and including elongated depRessions therein extending substantially the full extent thereof transverse to the adjacent edges of said abutting ducts, means connecting one edge of said plate in an air-tight manner with one wall of one duct to form an integral extension of said duct wall and to apply forces in one direction longitudinally of one edge, and means connecting the opposite edge of said plate in an air-tight manner with the adjacent wall of the other duct to form an integral extension of said adjacent wall and to apply forces in the opposite direction lengthwise of said opposite edge, said plate being distortable by said forces and the relative longitudinal movement of said adjacent edges, said connection accommodating said relative movements of said adjacent duct walls by shear distortion of said plate.

3. Means as claimed in claim 2 wherein said imperforate plate includes a plurality of panels, each panel extending continuously substantially entirely between said abutting ducts and joined in air-tight side-by-side relationship by weld seams extending only substantially parallel said elongated depressions transversely of the adjacent edges of said abutting ducts and each said panel includes a said elongated depression therein.

4. A torsionally distortable panel for connecting two adjacent members, which members are subject to movement longitudinally of the panel edge, said panel including a continuous sheet extending transversely substantially the entire transverse extent of said panel and having an elongated depression therein extending most of the transverse extent of said sheet, first means for connecting one edge of said panel with one of said adjacent members and second means for connecting the opposite edge of said panel with the other said adjacent member, said edge connecting means adapted to transmit the relative longitudinal movement of said members, and the resulting force couple, longitudinally to the opposite edges of said sheet, said sheet being deformable by said transmitted relative longitudinal movement, cause a skewing and torsional bending of said depression.

5. Means as claimed in claim 4 wherein the depth of said depression over most of its length is at least 1.5 times its width thereat.

6. Means as claimed in claim 5 wherein the length of a said depression is more than twice the width of said depression.

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