Patent Grant
11802691
Exemplary arrangements relate to a method for holding together adjacent grate bars in an incinerator or similar furnace device. Exemplary arrangements further relate to an apparatus including grate bars that are held together and reliably fixed in operative connection.
Grate bars which are sometimes alternatively referred to as grate steps, grate elements, grate plates or grate modules, are used in incinerators such as refuse incinerators to form a grate cover which supports combustible fuel material that is burned in the incinerator. The grate cover which is comprised of the adjacent grate bars, includes a fuel supporting side which includes a surface that may include openings therethrough. The openings serve to supply the air through the fuel supporting surfaces of the grate bars that is necessary for combustion (“primary air”). In some exemplary arrangements devices that are operative to cause relative movement of the grate bars provide movement and circulation of the fuel (“stoking”). In some exemplary arrangements the devices that are operative to cause relative movement of the grate bars operate automatically to facilitate the combustion of the fuel that is supported on the grate bars.
Exemplary arrangements of incinerators including grate bars are shown in U.S. Pat. Nos. 9,845,951; 6,938,563; 10,753,604; 8,939,094; 7,975,628; 5,950,548; 5,899,150; and 6,378,447, the disclosure of each of which is incorporated herein by reference in its entirety.
Exemplary arrangements relate to an inclined/moving grate. Such an arrangement of grate bars may be similar to a generally flat stairway similar to that shown in the incorporated disclosures with the slope generally between 0° and 30°, and such as for example between 24° and 26°. Such an incline between a 0° to 30° slope is referred to herein as horizontal but a grate with more than 0° slope may be referred to herein as an inclined grate. The combustible fuel is moved over the grate comprised of the grate bars. The fuel in exemplary arrangements is moved by grate steps which are comprised of the grate bars, relatively moving and transporting the fuel in operative supported connection with the grate bars. Depending on the direction of grate bar movement, the grate that is comprised of the grate bars may also be referred to as a pusher grate or a reciprocating grate. In each case the combustible fuel is moved in a forward direction within the incinerator in supported relation with the upper fuel supporting sides of the grate bars of which the grate is comprised.
Inclined grates comprised of grate bars are used for coarse and high-ash fuels that require robust stoking, such as household and commercial waste, biomass, waste wood, processed waste and/or lignite (which is rarer currently).
Grates, particularly inclined grates may be comprised of a plurality of grate bars. Such grate bars are often required to be firmly connected together and/or are movable relative to one another in order to move the combustible material on the upper, fuel supporting side of the grates.
Such incinerator grates comprised of grate bars generally include openings to enable supplied air to flow through the grate bars to facilitate combustion of the fuel. To provide such air flow, opening recesses may be provided in the sidewalls of the grate bars and/or openings may be provided on the upper sides and/or the front sides of the grate bars. Such openings enable air that is conveyed to an area on a lower side of the grate bars, to pass between the grate bars or through the grate bars to the bed of combustible fuel that is supported on the grate bars.
The high temperatures and forces moving the grate bars in order to stoke and transport combustible material may result in relatively large forces being generated. Such large forces may adversely affect the fasteners holding the grate bars in connected relation and may change the relative positions of the grate bars. For example in some cases such unwanted relative movement of the grate bars may result in a grate bar being moved sideways away from the immediately adjacent grate bar resulting in undesirable slits between the adjacent grate bars or such adjacent grate bars becoming wholly or partially disconnected.
Grate bars used in grates for supporting fuel combusted in incinerators and similar furnace environments may benefit from improvements.
Exemplary arrangements described herein provide improved fuel supporting grates configured for use in incinerators and similar furnace environments, and methods of making such grates, that are comprised of a plurality of grate bars. In exemplary arrangements the grate bars are arranged in parallel side by side relation to form a grate, or in some arrangements a grate step which is used in conjunction with a plurality of other grate steps.
In some exemplary arrangements grate bars are arranged to be held together parallel and adjacent to one another in pressed together relation during operation. The grate bars are held together with fasteners which in some arrangements may include clamps, threaded fasteners, pins, screws or other fastener types which are suitable for holding adjacent grate bars in pressed together relation.
In some exemplary arrangements the grate bars are connected so as to be selectively detachable from other grate bars. In exemplary arrangements this enables grate bars that have been damaged during operation to be replaced without having to replace the entire grate or grate step. This is accomplished in some exemplary arrangements by positioning the fasteners which hold grate bars together away from the upper side of the grate bars which supports the fuel thereon. Such positioning away from the fuel supporting surfaces of the upper sides of the grate bars helps to reduce the harmful effects of temperature and corrosion on the fasteners.
Further exemplary arrangements facilitate the ability to access the fasteners that hold the grate bars in pressed together relation. Further the exemplary arrangement reduces the risk that the fastener may fall out from engaged relation with each of the adjacent grate bars when it is not desired, such as during placement of the fastener in engagement with the grate bars, during manipulation to tighten the fastener and/or during operation of the incinerator.
In exemplary arrangements a method of making the incinerator grate includes positioning a pair of grate bars in adjacent parallel horizontal side by side relation. Each grate bar includes a respective upper side configured to support the fuel burned by the incinerator thereon. The upper side of each grate bar further includes a recess that extends therein.
With the grate bars in adjacent relation the method further includes manipulating a fastener through the respective recesses of the respective adjacent grate bars. The fastener is manipulated through the recesses so that the grate bars are held in pressed together relation by the fastener. In some exemplary arrangements the recesses each extend from a respective edge that bounds the upper side that supports the fuel on the respective grate bar. The recesses are aligned so as to produce a common opening that spans between the upper sides of the adjacent grate bars. This provides greater access through the common opening to the fastener and facilitates manipulation thereof.
Further in some exemplary arrangements each respective grate bar includes a respective projection. The respective projections extend upwardly and terminate below the recesses, and extend perpendicular to the respective upper side of the grate bar of which the projection is a part. In some arrangements the respective projections are positioned in side by side relation when the grate bars are positioned in adjacent relation. In exemplary arrangements the fastener can be extended through the common opening and manipulated to engage each respective projection of the grate bars and to hold the projections and the grate bars in pressed together relation. In some arrangements the fastener may comprise a clamp that is operative to engage and hold the projections in pressed together relation. In other exemplary arrangements each of the projections includes a slot. The slots may extend through the projections in a direction parallel to the fuel supporting upper sides of the grate bars and may be linearly aligned so as to receive a threaded fastener therein when the grate bars are in adjacent relation. The threaded fastener may be extended through the common opening to engage in the slots and be tightened by manipulation of the fastener to hold the grate bars in pressed together relation. Other types of fasteners may also be used in other arrangements.
In some exemplary arrangements at least one expansion piece may be positioned in operative connection with each of the grate bars. The expansion piece may have a coefficient of thermal expansion that is different than each of the grate bars. In such arrangements the at least one expansion piece is operative to cause the grate bars to be in pressed together relation with higher force at elevated temperatures.
In further exemplary arrangements the recesses or a common opening formed thereby are covered by at least one cover. The cover is operative to render the fastener inaccessible from the upper sides through the grate bars. In exemplary arrangements the cover serves to isolate the fastener from the upper sides of the respective grate bars that during incinerator operation are in contact with the high temperature and corrosive fuel material.
In some exemplary arrangements the cover includes a cover top that extends no higher than the adjacent upper side of the grate bar. In exemplary arrangements the cover top may be positioned flush with the upper sides of the adjacent grate bars. Such a configuration may be particularly useful when the grate bar is configured to have another grate bar move on the upper side thereof including the area in which the cover is installed.
In some exemplary arrangements the cover may be secured in the at least one recess or a common opening by being anchored in the opening by a wedge. The wedge may be installed using an interference fit between a side surface of the cover and a surface bounding the recess or common opening. The force resulting from the interference fit between the wedge, the cover and the grate bars is operative to securely hold the cover and wedge in the operative positions. Further, in some arrangements it may be further desirable to weld the cover and the wedge in fixed connection with each other and/or in fixed connection with the adjacent grate bar.
Further in some arrangements while the fastener is accessible through the recesses on the upper side for purposes of manipulation such as positioning and tightening, in other arrangements access to the fastener from a lower side opposed of the upper side of the grate bars may be provided. This may provide mechanics who service the incinerator with additional options for adjustment, repair and replacement of grate bars.
Further exemplary arrangements and methods are described in greater detail herein.
Referring now to the drawings and particularly to
The exemplary grate bar includes an upper side 3 which is substantially flat, but which has an elevation 5 toward the front end 4. In exemplary arrangements the upper side is a fuel supporting side of the grate bar when in the operative position in an incinerator or similar furnace structure. The exemplary grate bar 2 includes recesses 7 and 8 on opposed transverse sides of the grate bar. The recesses extend in aligned relation within the upper side of the grate bar and extend inward from respective opposed edges which bound the upper side as shown. As later discussed each of the recesses are configured to receive a fastener therein, which fastener is operative to hold the grate bar in connection with an adjacent grate bar in an area below the elevation 5 and the flat region 6 on the upper side of the grate bar. It should be understood that although in
As can be appreciated in this exemplary arrangement the common opening which is comprised of the two immediately adjacent recesses 8 and 13, enables accessing the fastener so that the fastener can be manipulated from the top through the common opening such as by being installed in operative connection with each of the grate bars and manipulated so as to tighten the threaded fastener using wrenches or other tools that are extended through the common opening. As can be appreciated in the exemplary arrangement tightening of the fastener causes the immediately adjacent grate bars to the held in pressed together relation by the fastener.
In the exemplary arrangement shown the side surfaces of the respective grate bars below the respective recesses in transverse cross-section, include upward extending projections which may be alternatively referred to herein as side parts. The upward extending projections extend perpendicular to the upper side of the respective grate bar. The exemplary projections 59 terminate upwardly below the recess opening. In the operative position of the grate bars shown in
In some exemplary arrangements the threaded fastener or other fastener that engages the grate bars in pressed together relation may serve as an expansion piece. For example in the exemplary arrangement shown the threaded fastener may have a different coefficient of thermal expansion than the grate bars. For example in exemplary arrangements the threaded fastener or other fastener type may be comprised of material that has a coefficient of thermal expansion that is smaller than the coefficient of thermal expansion of the material of the grate bars. The thermal expansion of metals and alloys is normally expressed as linear expansion which is proportional to a linear expansion coefficient indicating the length of the unit of length at a 1° increase in temperature between 0 to 100° C. The linear expansion coefficient is, for example, 1.0 for Ni steel, 30 Ni. However, for Ni steel, 20Ni, the linear expansion coefficient is as high as 19.5. This means that a threaded fastener or clamp with a lower coefficient of thermal expansion than the grate bars will expand less when heated up to 500° C., for example, in the area of the grate bars than a grate bar that is made of cast steel.
In exemplary arrangements such as those shown in
In an exemplary arrangement when in the operative position of the grate bars, the adjacent recesses 8 and 13 form a common opening, and the opening is closed by at least one cover 15. The exemplary cover is operative to render the fastener inaccessible through the recesses in the upper sides of the grate bars. The cover further serves to isolate the fastener from the upper sides of the grate bars upon which surface the fuel burned in the incinerator is supported. In the exemplary arrangement the cover is comprised of a plate portion 16. A wedge such as a tapered wedge 17 is installed with an interference fit through a pressed inward engagement between a plate portion of the cover and at least one surface bounding the recess of the common opening. In the exemplary arrangement the interference fit provided by the wedge is operative to secure the cover in closing relation with the recesses and the common opening. Of course it should be understood that this approach is exemplary and in other arrangements other approaches may be used.
While in the exemplary arrangement shown a pair of grate bars is in operative side by side fastened relation, it should be appreciated that to produce a grate cover 18 which may be a grate step comprised of the exemplary grate bars shown, a larger number of grate bars are joined together in abutting side by side relation with the upper sides of the grate bars mostly in a common plane. The number of grate bars utilized to form the cover grate depends on the configuration of the particular grate bars and the size of the grate to be utilized in the particular incinerator or furnace device. Of course it should be understood that these configurations are exemplary and in other arrangements other configurations and approaches may be used.
In some exemplary arrangements the exemplary cover 15 includes a cover top 61. In the operative position of the cover, the cover top outwardly bounds the cover and is disposed no higher outwardly than the respective adjacent upper sides of the grate bars. In an exemplary arrangement the cover top extends flush with the upper sides of the grate bars in order to minimize the risk of catching fuel materials or structures of other grate bars that may move on the upper side of the grate bars across the cover top. Of course this approach is exemplary and in other arrangements other approaches may be used.
The exemplary cover further includes an inner side 62. In the exemplary arrangement in the installed position of the cover 15, the inner side 62 is in operative engagement with the tops of the abutting projections 59 of the respective grate bars. Of course in some arrangements where the projections are held in engaged relation by a clamp that spans the tops of the projections, the inner side may be in operative engagement with the tops of the projections through the clamp.
The exemplary cover further includes a cover projection 24 which may be alternatively referred to as an undercut. The cover projection 24 is in operative connection with and in the exemplary arrangement is an extension on the inner side 62 of the cover. In the operative position of the cover, the cover projection 24 extends in engaged relation in a cover projection engaging recess 63. The exemplary cover projection engaging recess 63 extends in the interior area of the grate bar 2 and is disposed below the upper side 3. The exemplary cover further includes a similar further cover projection 25 that is disposed on an opposed side of the cover from the cover projection 24. The further cover projection 25 is in operative connection with the inner side of the cover, and in the operative position of the cover is engaged in a further cover projection engaging recess 64. As shown in
As can be appreciated this exemplary arrangement enables the cover to be inserted through the common opening that is comprised of the adjacent recesses 8 and 13 which make up the common opening, and to be positioned such that the cover projection 24 is engaged in the projection engaging recess 63 and the cover projection 25 is engaged in the projection engaging recess 64. Further the inner side 62 of the cover is operatively supported on top of the vertically extending projections 59. As a result the cover is held in closing relation with the common opening so that the wedge 17 can be press fit into the space between the side of the cover and the side surface of the grate bar 12 bounding the recess 13.
In some arrangements the force provided by the interference fit of the wedge is sufficient to hold the cover in the operative position and to prevent it from falling out during incinerator operation. This might be done in some arrangements by having the cover and/or the wedge comprised of material having a higher coefficient of thermal expansion than the grate bars. In some exemplary arrangements this may make it relatively easier to remove the wedge for repair purposes. In such cases with the wedge removed the cover 15 may then be moved to disengage the cover projections from the projection engaging recesses so that the cover may be removed from the common opening. This facilitates accessing and manipulating the underlying fastener for purposes of repair or replacement activities.
Further it should be understood that in some exemplary arrangements after the wedge 17 has been installed, the wedge and cover may be welded together. In such exemplary arrangements where the materials of the wedge and the cover are comprised of the material that may be welded together such as steel, the welding together of the wedge and the cover secures the cover in closing relation with the common opening. This approach may be used in situations where the grate bars are comprised of a cast material or other material to which the cover and/or wedge cannot be securely welded. However, in other exemplary arrangements the cover and/or wedge may be welded in fixed engagement with one or both of the grate bars to hold the cover and the wedge in fixed engagement with the grate bars. Of course it should be understood that these arrangements are exemplary and that in other arrangements other approaches may be used.
An alternative exemplary arrangement for holding the adjacent grate bars 2 and 12 in pressed together relation is shown in
In exemplary arrangements the clamp 30 may serve as an expansion piece by being comprised of a material with a smaller coefficient of thermal expansion than the adjacent grate bars. For example the grate bars may be comprised of cast steel material. The clamp may be manipulated through the common opening by placement and engagement over the adjacent projections 31 and 32. In the exemplary arrangement where the clamp has the lower coefficient of thermal expansion, when the incinerator is at a high temperature the clamp expands to a lesser extent than the grate bars. As a result the exemplary U-shaped clamp is operative to hold the grate bars more tightly in pressed together relation during incinerator operation than when the incinerator is cool and the grate bars are at ambient room temperature.
However in this exemplary arrangement shown in
In some exemplary arrangements the enlarged heads 57, 58 of the pin 50 may be comprised of nuts engaged with a threaded rod 56 or other components of a threaded fastener. In such exemplary arrangements the coefficient of thermal expansion may be selected for each of the components so that the grate bars are held in pressed together relation even in the event of large fluctuations in temperatures. Of course it should be understood that these approaches are exemplary and in other arrangements other approaches may be used.
As can be appreciated the exemplary arrangements shown herein may provide benefits by holding together adjacent grate bars through fasteners that are operative to hold the grate bars together in operatively engaged side by side relation. In the exemplary arrangements the fasteners utilized to hold the grate bars in engaged relation may be manipulated through the respective recesses of the grate bars. Such manipulation may include tightening the fastener through the openings provided by the recesses. Further the ability to install a fastener from the top through recesses in the upper sides of the grate bars may avoid the need for the mechanics performing such work to access the undersides of the grate bars which may be obstructed by various types of equipment and mechanisms.
Further in the exemplary arrangement the exemplary recesses provide access for manipulation of the underlying fastener. This may be done by having recesses which provide a common opening that is sufficiently large to enable wrenches or other suitable tools to manipulate the fastener so as to tighten or loosen or release the fastener as necessary to suitably engage and disengage the adjacent grate bars. The exemplary cover arrangement further serves to isolate the underlying fastener from the heat and corrosive materials which may be present in the incinerator or other furnace environment at the upper side of the grate bars which support the fuel that is burned in the incinerator.
Further in exemplary arrangements the cover is provided with a secure connection with the grate bars and is configured to resist separation from the grate bars and displacement from the recesses during operating conditions. However in the exemplary arrangement the cover can be removed by either cutting the cover or the wedge with a cutting torch, saw or chisel and prying it out so as to be relatively readily removed when desired. This facilitates repair or replacement of the grate bars. These and other useful aspects may be provided by the exemplary arrangements.
Further in the exemplary method of producing the exemplary arrangement of grate bars a series of steps may be carried out. For example in the exemplary arrangement the grate bars are positioned in adjacent relation, such that the grate bars are positioned horizontally in supported relation with a carriage or other suitable grate supporting structure. In this exemplary positioning step the upper sides of the grate bars that are configured to support the fuel in the incinerator are positioned in adjacent side by side relation with the edges that bound the upper sides of the grate bars in an immediately adjacent relationship.
In the exemplary method because the recesses extend in the respective upper sides of the grate bars inwardly from the respective bounding edges, in the positioning step the grate bars are positioned such that the respective recesses are in aligned relation and bound a common opening. Further in the exemplary method a fastener may be manipulated through the common opening. Such manipulation may include operatively engaging the fastener with each of the grate bars and/or tightening the fastener. This may be done in the manner like that discussed in the previously described arrangements such as by extending a central stem of a threaded fastener in the linearly aligned slots that extend in the vertically extending projections of each of the respective grate bars, and then tightening the threaded fastener. Further in other exemplary arrangements the step of manipulation may include engaging a clamp with a pair of immediately adjacent projections of the respective grate bars and moving the clamp to hold the grate bars in operatively engaged relation. Of course it should be understood that other types of manipulation may be carried out through the respective recesses to engage and secure the particular fastener in operatively engaged relation with each of the grate bars.
In a further exemplary step of the method of producing the grate bar arrangement, the fastener is manipulated through the respective recesses so that the grate bars are held in pressed together relation by the fastener. In some exemplary arrangements this may include tightening of a threaded fastener via engagement of the fastener through the recesses and/or common opening with wrenches or other suitable tools to tighten the fastener as previously discussed. Further in other exemplary arrangements the manipulation step may include engaging, applying or pressing a clamp through the recesses to cause projections or other structures of the immediately adjacent grate bars to be held in pressed together relation. Further in other exemplary methods other types of fasteners may be manipulated through the respective recesses in the grate bars to cause the grate bars to be engaged in operatively attached relation and to be fastened in pressed together connection.
In exemplary arrangements the method may further include the step of installing at least one expansion piece in operative connection with the grate bars. In the exemplary method the at least one expansion piece has a different coefficient of thermal expansion than each of the grate bars. In this exemplary arrangement the grate bars are caused to be pressed together with greater force with increased temperature.
In further exemplary arrangements after the grate bars are held in pressed together relation through manipulation of the fastener the method may further include the step of covering the recesses with at least one cover. Covering the recesses with at least one cover in the exemplary arrangement serves to separate and isolate the fastener from the upper side of the grate bars which supports the fuel in the incinerator. In the exemplary arrangement the covering step includes installing a cover that has a cover top that extends outward no higher than the adjacent upper sides of the grate bars. Further in exemplary arrangements the covering step includes installing a cover with a cover top that is flush with the upper sides of the grate bars. This minimizes the risk of fuel material collecting in a recess above the cover top and/or material moving over the upper side catching in engaged relation with the cover.
In exemplary arrangements the method may further include fixing the cover in the recesses by pressing at least one wedge operatively between the cover and at least one wall bounding a recess. In the exemplary method the wedge may be installed using a pressed in interference fit which is operative to hold the cover and the wedge in fixed engagement in the recess and/or common opening. Further the exemplary method may include welding the exemplary cover to be in fixed engagement with each of the grate bars. This may include in some arrangements, welding the at least one cover in fixed engagement with the wedge. This may be done in some arrangements in situations where the cover and the wedge can be welded together to form a solid covering filling the recess and/or common opening. This may be further done in some methods in situations where successful fixed welded connections cannot be accomplished between the material of the cover and/or wedge and the grate bars. However in other exemplary arrangements the welding of the at least one cover to be in fixed engagement with each of the grate bars may include directly welding of the cover and/or the wedge to each of the grate bars where the materials enable such welding.
In further exemplary methods the cover may include cover projections that are in operative connection with an inner side of the cover and are disposed in opposed cover sides. The method may include a cover engaging step that includes engaging a cover projection with a cover projection engaging recess in one grate bar, and engaging a further cover projection with a further cover projection engaging recess in the other immediately adjacent grate bar. Further in some exemplary methods each grate bar may include a respective projection that extends perpendicular to the upper side of the grate bar and below the recesses. The exemplary cover engaging step may further include operatively engaging the inner side of the cover with the projections. Such engagement may be further operative to hold the cover positioned in the recesses and/or common opening.
Of course it should be understood that these method steps are exemplary and in other arrangements different or additional method steps may be utilized.
Thus the exemplary arrangements achieve improved operation, eliminate difficulties encountered in the use of prior devices and methods, and attain useful results described herein.
In the foregoing description certain terms have been used for brevity, clarity and understanding. However, no unnecessary limitations are to be implied therefrom because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover the descriptions and illustrations herein are by way of examples and the new and useful features are not limited to the exact features shown and described. Further it should be understood that the features and/or relationships associated with one arrangement can be combined with the features and/or relationships from another arrangement described herein. That is, various features and/or relationships from the various arrangements can be combined to produce further arrangements, and the new and useful scope of the disclosure herein is not limited solely to the arrangements specifically shown or described.
Having described features, discoveries and principles of the exemplary arrangements, the manner in which they are constructed, operated and carried out, and the advantages and useful results that are attained, the new and useful features, devices, elements, arrangements, parts, combinations, systems, equipment, operations, methods, processes and relationships are set forth in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 006 197.4 | Oct 2020 | DE | national |
| 10 2020 006 801.4 | Nov 2020 | DE | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20220113025 A1 | Apr 2022 | US |
