The furnace of steam boiler has internal pressure which is usually designed ± mm wg. The internal pressure is resisted by attaching buckstay in every. A buckstay arrangement for a furnace of a steam generator wherein the furnace tube walls (12) are supported by a plurality of independent buckstays (10). Sulekha Creative Blog – Buckstays are used in boilers to retain the shape of the furnace against various loads. The name ‘buckstay’ means staying buckling of.
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Similarly, it is contemplated that the elongated channel beam 72 in the buvkstay beam 70 embodiment of the present invention may also be formed of a plurality of shortened U-shaped channel members welded to the bkckstay plate 74 at spaced intervals along the length thereof with appropriate gaps therebetween while still providing sufficient polar moment of inertia to withstand the bending moments imposed upon the buckstay Some buckstay and membraned-tube wall attachment structures are disclosed in U.
USA – Furnace buckstay design – Google Patents
Upper and lower support plates are welded to the outside surface of the tubes, engaged with each buckstay by the engagement means. As shown in FIG.
The buckstays are customarily connected to the walls by any one of a variety of mean so that the forces on bucktsay walls will be transferred to the load sustaining buckstays. As the furnace expands differentially in a vertical direction, each level of buckstays would move a different amount under the influence of the vertical elongation of the furnace tube walls.
US4499860A – Furnace buckstay design – Google Patents
Newer Post Older Post Home. Additionally, a support rod 20 is interconnected between the mounting plate 22 and the upper edge of the outer end member 46 of the channel beam 40 at one or more locations along the channel beam 40 to support the dead weight of the buckstay An end connection buckstay bracket 36 is welded to each end of the buckstays 20, 22 near the corner It is to be understood that it is not necessary that the plate members 50, 60, 52 and 62 be formed of a single elongated plate but may also, within the scope of the invention, be formed of a plurality of shortened plate members disposed within the channel beam 40 at spaced intervals with a gap therebetween and still provide sufficient increase in the polar moment of inertia of the buckstay 10 to resist any bending moment imposed upon the buckstay 10 by positive or negative pressures within the combustion chamber enclosed by the furnace tube wall The elongated plate members may be disposed so as to extend transversely across the channel from the outer tip of one end member to the outer tip of the other end member parallel to the central member thereby forming a rectangular box-like section within the channel beam cross-section.
The elongated plate member 50 is welded to the outward end member 46 of the beam 50 along its interface with the upper edge of the vertical end member 46 and also to the central member 42 of the beam 40 at its interface therewith to form a triangular box-like section These rocker members serve to permit free deflection of the rod ends.
The present invention can reduce or eliminate tube failures in boiler membrane-walls due to excessive stress levels caused by start up and cool down temperature induced differential movements between the walls and the boiler buckstay system. Filler bars 44 may be welded inbetween adjacent tubes 16, on top of the membrane 18, to provide for greater surface area for welding the plural support plates 42 to the tubes The stirrup assemblies are best illustrated in FIGS.
Without the extended standoffs 26, the load capacity of the structure would be limited to a smaller level because the wall is so weak when loaded in that particular way. A first elongated plate member is mounted to the elongated channel beams so as to extend transversely across one of either the upwardly facing channel or the downwardly facing channel so as to form a box-like section within one channel of the I-beam corss-section. A buckstay system is provided on the outside of the walls 10, 12, and comprises at least one buckstay 20, 22 for each wall section 10, 12, respectively.
Brackets 27 on each end of the I beams 17 serve to anchor the ends of the rods 25 while similar brackets 28 are employed on the truss structures 18 to anchor the ends of rods The invention as set forth in claim 6 and further including means to slidably retain said rod means in said substantial direct contact with said Walls.
Each bracket comprises a tie plate 16 welded horizontally to the surface of the furnace tube wall 12 and a U-shaped support bracket 18 welded to the tie plate 16 and extending horizontally outward therefrom to receive and engage the buckstay 10 in such manner as to permit sliding movement between the buckstay 10 and the bracket The illustrated stirrups as well as the brackets to anchor the ends of the rods to the buckstays are only shown by way of example and many other types of each could be employed in the present invention.
A second extended standoff welded to a bumper plate and also to the tie bar moves in the space between the pads. Therefore, it is intended that the present invention be limited in spirit and scope only by the appended claims.
The support rod 20 is welded between the tie plate 22 and the upper outer edge of the buckstay 10 to provide a means for supporting the dead weight of the buckstay 10 from the furnace wall without placing an excessive bending moment on the bracket A buckstay system according to claim 1, wherein two such anchor assemblies are provided at the corner for each buckstay, one being located above and the other below each buckstay.
These forces tend to bend and buckle the walls as well as put the walls under tension. The boiler tube walls are subjected to combustion gas pressures which can be either positive or negative with respect to the local atmospheric pressure. Therefore, it has become customary and necessary to provide an arrangement of flanged girder beams, typically referred to as buckstays, that extend around the furnace to provide additional support to the furnace walls and prevent the dishing of the furnace walls in a horizontal direction as affected by pressure differential.
Additionally, a second elongated plate member 62 may be disposed so as to extend transversely across the downwardly facing channel 34 again parallel to the central member 42 between the lower end of the vertical end members 44 and 46 of the channel beam 40 to form a second rectangular box-like section 30′. With the I-beam 40 disposed with its central member 42 horizontal and its end members 44 and 46 vertical, an upwardly facing channel 32 is formed above the central member 42 of the beam 40 between the end plates 44 and 46 thereof and a downwardly facing channel 34 is formed beneath the central member 42 of the channel beam 40 between the end plates 44 and 46 thereof.
US3203376A – Buckstay arrangement for furnace walls – Google Patents
The present invention may be bcukstay understood and its novelty and unobviousness appreciated from the following description of the preferred embodiments shown in the accompanying drawings, wherein:. An end connection corner tie is welded at the corner to the pair of tie bars, and a pair of end connection buckstay brackets are provided, one end of each being welded to each end of the buckstays near the corner.
The extended standoffs 26 provide a moment resisting function.
This produces considerable stress in the tubular walls. As mentioned in the description of FIG.
A third extended standoff’s upper and lower ends are received within xesign formed by the other U-shaped plates and is engaged to its associated buckstay. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. A furnace as set forth in claim 2 wherein the ends of each of said rod means are bent outwardly away from said walls to the position where said rods are connected to said end portions of said buckstays.
When adjusting the furnace in the cold condition the ends of rods 25 and 26 are bent outwardly as shown in FIGS.
Alternatively, as shown in FIG. The engagement means thus supports the weight of the buckstays 20, 22 which, in effect, hang on the wall sections 10, As the load is transferred from the tie bar 31 to the wall 10 or 12, it must bridge an eccentricity equal to the tube radius plus half of the pad 46 thickness plus the support plate 42 thickness.
They may be formed of single beams such as I beams or they may be formed of a truss structure. The invention as set forth in claim 7 wherein said ends of said rod means are bent outwardly away from said walls to the position where said rod means are connected to said end portions of said buckstay means.
The end of the stirrup assemblies attached to dfsign buckstay assemblies will be at a point further away from the center than the end attached to the furnace Wall.
At least one buckstay extends across at least part of each wall section. A furnace for a steam generator or the like comprising two pairs of oppositely disposed upright Walls defining a chamber for hot gases, buckstay means extending transversely adjacent each of said walls, each of said eesign means having end portions, means supporting said buckstay means in spaced relationship to said walls, said supporting means including means to permit relative transverse thermal expansion between said walls and said buckstay means, a plurality of rod means each having two ends, one end of each of said rod means connected to an end portion of one of said buckstay means adjacent one of said walls, the other end of each of said rod means connected to the corresponding end portion of the buckstay means adjacent the opposite one of said walls, said rod means supported in transversely slidable relation to said walls.
The moment being resisted is generated by an eccentric load path. A buckstay system for a membraned-tube wall of a steam generator having a first wall section which meets a second wall section desigj an angle to form a corner. This is best illustrated in FIG.