Patent Application
20120103236
The present disclosure relates generally to a seal for sealing a gap between stationary and moving portions of a traveling grate stoker, and more particularly, to a seal configured for reduced wear and self-cleaning.
Stokers can be used to feed a fuel such as coal or biomass to and/or through a furnace for combustion on a traveling grate in an interior area of the furnace. Combustion of the fuel creates heat, pressure and combustion byproducts such as ash in the interior area of the furnace. The stokers generally include a stationary base secured to the floor beneath the furnace. Typical stokers include a seal defined by a sealing portion of the base which sealingly engages a plurality of plates that move with the traveling grate, for example on a chain conveyor system. The purpose of the seal is to ensure that a proper amount of air passes into the furnace to aid in the combustion of the fuel on the plurality of plates. Improper amounts of air can cause non-uniform combustion of the fuel and create hot spots, causing deterioration and premature failure of the plurality of plates that move with the traveling grate.
Moreover, the seal is subject to mechanical wear because the plates move relative to the sealing portion of the base. In addition, the combustion byproducts are typically abrasive and can migrate into the seal. The abrasiveness of the combustion byproducts can accelerate wear of the seal, which will increase the gap through which an improper amount of combustion air can enter the furnace.
According to aspects illustrated herein, there is provided a sealing apparatus for use with a traveling grate stoker used for the delivery of fuel to an interior area of a boiler for combustion. The sealing apparatus includes a base and one or more legs extending upwardly from the base. The sealing apparatus also includes at least one flange extending outwardly from one or more of the legs. The flange includes a surface extending between the leg and one or more edges of the flange. The surface includes a sealing portion adjacent to the leg and one or more discharge portions sloped downwardly from the sealing portion to one or more of the edges, for a self cleaning discharge of wear materials therefrom. The sealing portion is positioned proximate to a portion of the traveling grate and defines a gap therebetween. The gap is configured to mitigate flow therethrough. The seal is useful in preventing abrasive combustion byproducts from entering into and mitigating wear between the flange and the portion of the traveling grate.
According to other aspects illustrated herein, each of the legs includes an extension projecting from an end thereof. Each of the extensions defines an outwardly facing side sealing surface. Each of the side sealing surfaces are positioned proximate to an edge of the travelling grate and define another gap therebetween, which is configured to mitigate flow therethrough.
According to other aspects illustrated herein, a portion of the traveling grate defines an upwardly facing conveying surface and each of the at least one legs includes an extension projecting from an end thereof. Each of the extensions has an edge, which is approximately flush with the conveying surface. The extensions serve as a dam to prevent byproducts from entering the gap between the sealing portion of the flange and a portion of the traveling grate.
According to other aspects illustrated herein, one of the discharge portions is a side-discharge portion that is sloped downwardly from the sealing portion to a lateral edge of the flange. The side-discharge portion is configured for self cleaning of combustion byproducts therefrom.
According to other aspects illustrated herein, another one or more of the discharge portions is an end-discharge portion that is sloped downwardly from the sealing portion to a distal end of the flange. The end-discharge portion is configured for self cleaning of combustion byproducts therefrom and also prevents carryover of the byproducts from one flange to another downstream flange.
According to other aspects illustrated herein, one or more gusset members are disposed between the legs and the base. A portion of the gusset member extends from the base to a position below a conveying surface of the traveling grate and serves as a support member between the legs.
The above described and other features are illustrated by the following figures and detailed description.
Referring now to the Figures, which are exemplary embodiments, and wherein the like elements are numbered alike:
As shown in
As shown in
During operation, the fuel 34 is combusted on the conveying surfaces 32 in an oxygen rich area 38 of the interior area 18 of the boiler 10, located generally above the conveying surface. The combustion process creates byproducts 40, such as ash and other abrasive materials, some of which can accumulate on the stationary seal portion 24 adjacent to the gap G1. As described below, the seal 22 has utility in mitigating the introduction of the byproducts 40 into the gaps G1 and G2 and between the stationary seal portion 24 and the plate assemblies 26, reducing wear and thereby prolonging the life of the seal.
Referring to
Each of the legs 42 includes a flange 52 extending outwardly from a distal end 42E of each leg. Each of the flanges 52 define a surface 53 extending from the respective leg 42 to a lateral edge 52L and extending between leading 52A and trailing edges 52B (i.e., distal edges or distal ends) of the flange 52. The lateral edge 52L is generally parallel to the leg 42; and the leading 52A and trailing 52B edges are generally perpendicular to the lateral edge 52L. Each of the surfaces 53 include a sealing portion 55 positioned adjacent to the leg 42. The surface 53 and in particular the sealing portion 55 of the flange 52 is positioned in close proximity to an underside 26U of the plate assemblies 26 to seal the gap G2 therebetween.
Each of the legs 42 includes an extension 36 projecting upwardly from the distal end 42E of each leg and having and edge 36E that is approximately flush with the conveying surface 32 of the traveling grate 18. The extensions 36 includes an outwardly facing side portion which defines a sealing surface 59 which is generally parallel to and positioned in close proximity to an edge 26E of each of the plurality of plate assemblies 26 to seal the gap G1 therebetween. As explained further below, the extension 36 serves as a dam to prevent the combustion byproducts 40 from migrating laterally into the gap G2, from the channel 46. In one embodiment, the sealing portion 55 of the surface 53 of the flange 42 is positioned adjacent to the extension 36.
The surface 53 of the flange 52 is sloped downwardly from a junction between the sealing portion 55 and the extension 36 at an angle S of about eight degrees with respect to a horizontal reference line H. Such a configuration defines a progressively increasing opening 56 between the flange 52 and the underside 26 U of each of the plate assemblies 26. The opening 56 defines an outlet or side-discharge portion for discharge of the byproducts 40 which may have been introduced into the opening through the gaps G1 and G2. The slope of the flange 52 facilitates gravity forced movement and/or self cleaning of the byproducts 40 off the flange and out of the opening. Removal of the byproducts 40 from the flange 26 reduces wear and extends the life of the seal. Although the upwardly facing surface 53 is shown in the illustrated embodiment at an angle sloped downwardly eight degrees from the horizontal, the slope is not limited in this regard as other configurations including but not limited to any downwardly sloped angle, surfaces having multiple slopes, portions being horizontal, portions having curved surfaces and combinations thereof can be employed without departing from the broader aspects disclosed herein.
Referring to
Referring to
During operation, the byproducts 40 swirl around in the interior area 12 in multiple directions A. A portion of the byproducts 40 settles on top of the sand in channel 46 and between the extensions 36. After a period of operation, as a result of a damming action by the extensions 36, the byproducts 40 form a pile P above the channel 46 and the conveying surface 32. After a further period of operation, the byproducts 40 fall off the pile P as shown by arrow B, onto the plate assemblies 26, which carry the byproducts away from the gaps G1. Because the extensions 36 provide a dam or barrier mitigating lateral movement of the byproducts 40 into the gaps G1 and G2, the pile P protrudes above the conveying surface 32 and the byproducts 40 fall onto and are carried away by the plate assemblies 26. Therefore, migration of the byproducts 40 into the seal 22 is mitigated. Reducing the migration of the byproducts 40 into the seal 22 reduces wear and increases life of the seal.
Referring to
While the invention has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
