EP3994392A1

EP3994392A1 - Grate block for a combustion grate

Info

Publication number: EP3994392A1
Application number: EP20735397.0A
Authority: EP
Inventors: Maurice Henri Waldner
Original assignee: Hitachi Zosen Innova AG
Current assignee: Hitachi Zosen Innova AG
Priority date: 2019-07-05
Filing date: 2020-07-01
Publication date: 2022-05-11
Also published as: BR112021025791A2; MX2022000118A; JP2022538489A; WO2021004852A1; US20220282864A1; CN114450520A; KR20220030240A; CA3145801A1; AU2020312113A1

Abstract

The invention relates to a grate block (10) for a combustion grate. The grate block (10) comprises a block body (12) having an upper wall (14) which forms a bearing surface (16) and along which the combustible material is to be conveyed and a front wall (20) which has a lower bearing edge (23), said bearing edge (23) being designed to come into contact with the bearing surface of an adjacent grate block in a feed direction S, wherein the upper wall (14) has an air supply opening (35) formed by an air supply channel (38). The air supply opening (35) is at least partially surrounded by a thickened portion (50) which protrudes from the bearing surface (16), forms a protective channel (57) extending the air supply channel (38), and is designed to prevent liquid from flowing into the air supply opening (35).

Description

Grate block for a combustion grate

The invention relates to a grate block for a combustion grate according to the preamble of claim 1 and a method for producing the same according to the preamble of claim 12. Furthermore, the

Invention a molded part for attachment to an upper wall of a grate block forming the combustion grate.

The invention further relates to a combustion grate comprising at least one such grate block and the use of said combustion grate for the

Incineration of waste, as well as a

Waste incineration plant including such

Combustion grate.

Incineration grates for the large-scale incineration of waste have been known to the person skilled in the art for a long time. Such combustion grates can take the form of

There are thrust combustion grates, which include moving parts that are suitable for carrying out stokes. The material to be fired is conveyed from an inlet-side end of the combustion grate to its outlet-side end and is burned during this. In order to supply the combustion grate with the oxygen required for combustion, appropriate air supply lines are provided, which lead through the combustion grate and through which the air, also called primary air, is introduced.

A frequently used combustion grate is the so-called step grate. This encompasses side by side arranged grate blocks each forming a row of grate blocks. The rows of grate blocks are arranged one above the other in a step-like manner, with the front end of a grate block, viewed in the pushing direction, rests on a support surface of the adjacent grate block in the transport direction and is moved on this support surface with a corresponding pushing movement.

In the case of so-called push-back grids, the grate blocks are arranged rotated by approximately 180 ° in relation to the feed grids, viewed in the transport direction of the material to be fired. In the case of push-back grates, the front end of the grate block, viewed in the pushing direction, therefore rests on a support surface of the previous grate block. In contrast to moving grates, the direction of pushing of the moving grating is opposite to the direction of transport resulting from the inclination of the moving grate.

A combustion grate is disclosed in DE 195 02 261 A1, which comprises several rows of grate bars which, viewed in the transport direction of the fuel, are arranged one behind the other like a staircase. Furthermore, the combustion grate comprises support grate bars, which have a shape similar to the grate bars and are shortened in accordance with the length of a nozzle plate. In one embodiment, the nozzle plate can be formed by a hollow nozzle box, in which, viewed in the transport direction of the material to be fired, several rows of air nozzles, in particular vortex nozzles, are integrated in the front and in the front, upper section are. The formation of the vortex nozzles is not dealt with in detail. The nozzle plate is provided with a device with which it can be hung on the support grate. A so-called vortex nozzle grate path is formed by several support grate bars and nozzle plates suspended from the support grate bars, and can run across the width of the combustion grate. The vortex nozzle grate path can be acted upon with compressed air and vortex air independently of a primary air system of the combustion grate. The fuel or slag layer is torn open and circulated with a pulsed compressed air supply. The circulation achieved leads to a loosening of the fuel on the grate, which enables an improved burnout of incompletely burned fuel particles. Furthermore, the compressed air pulses cause the nozzle plates to self-clean, since fuel or ash particles that have penetrated the air nozzles are blown out again.

A grate bar for an incineration grate is disclosed in DE 20 2017 006429 Ul, the incineration grate comprising several rows of grate bars which, viewed in the transport direction of the fuel, are arranged one behind the other like a staircase. The grate bar comprises a front foot section and an upper running surface for the front foot section of a grate bar of a higher row of grate bars. The running surface has a contouring with an elevation and / or depression for deflecting the grate bar of the higher row during the advancing movement of the rows of grate bars of the combustion grate. However, the deployment will of air intakes in the grate bars are not covered in this document.

A grate plate made of cast steel for transporting and cooling, heating, drying or burning bulk material is disclosed in DE 298 07 161 U1, which has troughs arranged in a grid shape on its upper side. Air passage holes are arranged in the troughs. The formation of the opening of the air passage holes in the troughs, ie in a plane which is below the plane of the top of the grate plate, makes use of the knowledge that the larger pieces of material in the bulk material move over the top of the grate plates without hitting the edges to poke the air passage holes. In addition, after a certain time, a thin layer of fine material settles in the troughs, which acts as a cushion, so that the edges of the air passage holes are protected. Thus, the passage of air is ensured for a long time without the need to inspect the grate plates.

Grate blocks are exposed to very high thermal loads, mainly because of the high temperatures during combustion or in the furnace. During normal operation of the combustion grate, this thermal load becomes high, particularly in the area of an upper wall of the grate block that forms the support surface and along which the material to be fired is conveyed and a front wall of the grate block that forms a pushing surface for pushing the material to be burned.

Very high loads occur when the material to be fired is unevenly distributed on the combustion grate and only a thin, heat-insulating layer of firing material is formed locally or is completely absent. This thermal load promotes erosion through abrasion and chemical reactions taking place on the contact surface, which further damage the contact surface. This ultimately leads to a reduction in the service life of the grate block.

To cool a grate block and to supply air to the combustion grate, air supply ducts forming air supply openings can be formed in the upper wall and / or in the front wall.

In the case of the air supply channel formed in the upper wall in particular, clogging by the items to be fired and / or by combustion residues can occur, so that the air supply for cooling the grate block and for promoting the combustion of the items to be fired is no longer efficient. This ultimately leads to an increased maintenance effort and a reduced service life of the grate block. Furthermore, the fuel contains materials which can at least partially become liquid during combustion, for example metals, plastics or tars. In the present application, the term “fraction” of the material to be fired refers to these materials contained in the material to be fired, and the fraction in the liquid state is referred to as the “liquid fraction”.

The liquid fraction can also flow into the air supply channel and lead to impairment of the air supply, especially in the case of the upper one Wall formed air supply duct. In the solidified state, this fraction can even lead to a permanent blockage of the air supply duct.

EP 0 167 658 A1 describes a grate block for building a combustion grate which comprises a box-like block body. The block body has an upper wall forming a support surface for items to be fired, the upper wall having air supply openings formed by air supply channels for introducing gas, in particular air, into the items to be fired and for cooling the grate block. In one embodiment, the air supply openings are designed as slots and, in

Cross-section viewed, curved like a siphon at its gas inlet against gravity, in order to form an obstacle to the ingress and fall of firing material or combustion residues through the air supply openings. Because the upper wall has air supply ducts, it can be cooled. However, the disclosed design of the air supply channels supports an accumulation of items to be fired in the liquid state in the air supply channels.

The object to be solved according to the invention is to provide a grate block mentioned at the beginning, in which, in operation, the risk of the air supply being impaired through the air supply channels is minimized.

This object is achieved by the grate block defined in independent claim 1. Preferred embodiments of the grate block according to the invention are given in the dependent claims.

According to claim 1, the present invention thus relates to a grate block for an incineration grate in which successive grate blocks are arranged one above the other in a step-like manner and are designed in such a way as to shift and convey material to be burned by means of relative pushing movements. In a known manner, these thrust movements can be carried out, for example, by means of relative movements between grate blocks of different stairs of the combustion grate. As mentioned above, such combustion grates are also referred to as step grates. Furthermore, the grate block comprises a block body preferably designed as a cast part. As a rule, the block body is designed essentially in the form of an elongated cuboid with a longitudinal axis L.

The block body comprises an upper wall which forms a support surface along which the material to be fired is to be conveyed and which defines a side of the material to be fired of the upper wall. Viewed in a thrust direction S, the foremost end of the bearing surface forms an edge over which the bearing surface drops into a thrust surface formed by a front wall.

The side of the upper wall facing away from the support surface and the side of the front wall facing away from the thrust surface define a cooling air side of the block body. Furthermore, the front wall is designed in its lowermost area in the form of a foot, which is intended to rest on the support surface of a grate block adjacent in the thrust direction S. In a preferred embodiment, in which the grate block according to the invention is intended for a moving grate, the foot thus rests on the grate block following in the transport direction T of the material to be fired or its support surface. However, it is also conceivable that the grate block according to the invention is intended for a return grate; in this case the foot rests on the grate block or its support surface that is preceding in the transport direction T of the material to be fired.

The pushing direction S denotes the direction in which the material to be fired is pushed by the pushing surface of the grate block. As a rule, the direction of thrust S is parallel to the longitudinal axis L.

The transport direction T denotes the direction of movement of the fuel from an inlet to an outlet of the combustion grate. The transport direction T results mainly from the inclination of the combustion grate.

At least the front support edge of the thrust surface is arranged in a plane E which runs essentially at right angles to the longitudinal axis L. In this regard, it is conceivable that a surface arranged in the lowermost area of the front wall, the lower end of which is formed by the front support edge, is arranged in plane E. However, it is also conceivable that only the line described by the front support edge is arranged in plane E.

Furthermore, the upper wall has an air supply opening which is formed by an air supply channel extending through the upper wall. In the context of the present application, the air supply opening is also to be understood as an air supply outlet. As a result, an optimal air supply to the combustion grate or to the combustion bed on the combustion grate is obtained, which contributes to a very high burnout of the material to be burned.

In the following, the term "air" includes the so-called primary air which is supplied to the combustion grate or the combustion bed on the combustion grate. The primary air primarily contributes to the burnout of the material to be burned but at the same time also to the cooling of the grate blocks of the combustion grate.

The front wall can have a further air supply opening, which is formed by further air supply ducts for supplying air to the combustion grate, viewed in a longitudinal section, running at right angles or at an angle to the thrust surface. This also supports the burnout of the material to be fired.

According to the invention, the air supply opening is at least partially surrounded by a thickening protruding from the support surface. The thickening forms a protective channel that extends the air supply channel and is intended to prevent liquid from getting into the air supply opening. The material to be fired can contain a fraction which, during combustion can at least partially become liquid, as has already been explained above, and can flow into the air supply channel. As a result, the air supply is impaired, so that the combustion of the fuel and the cooling of the grate block do not proceed efficiently. The provision of the thickening according to the invention leads to the liquid fraction flowing around the thickening instead of penetrating into the air supply channel. The risk of a blockage in the air supply duct can thus be reduced. In particular, clogging of the air supply channel by the fraction in the solidified state can be reduced.

The air supply opening is preferably completely surrounded by a thickening projecting from the support surface. This means that the thickening forms a continuous border around the air supply opening. In this way, the liquid fraction can be at least approximately prevented from being sucked into the protective channel and then into the air supply channel.

The protective channel is enclosed by an inner flank of the thickening. Furthermore, the thickening has an outer flank adjoining the inner flank and sloping down on the side facing away from the protective channel. The outer flank thus basically corresponds to the outer area of the thickening exposed to the item to be fired. In this context, the term “flank” defines a lateral, possibly inclined, thickened wall.

The protective channel comprises a lower protective channel opening on the end of the protective channel facing the support surface and an upper protective channel opening on the end of the protective channel facing away from the support surface, ie on the side of the thickening facing the item to be fired.

In one embodiment, the inner flank can be formed adjacent to the air supply opening, i.e. the lower protective channel opening surrounds the air supply opening. The term “adjacent” is to be understood in such a way that an area of the bearing surface around the air supply opening can be present between the air supply opening and the inner flank. Such an arrangement can occur, for example, after a repair, when a replacement thickening is welded around the air supply opening, as will be explained below, the clear opening of the protective channel of the replacement thickening being wider than the clear opening of the protective channel of the previous thickening. In this regard, however, it should be noted that the protective channel in this embodiment forms a kind of collecting area for the items to be fired and the remains of incineration via its widening. In order to keep this effect within limits, the contour of the lower protective channel opening advantageously runs as close as possible to the contour of the air supply opening.

The inner flank is particularly preferably formed directly adjacent to the edge of the air supply opening. In other words, the inner flank begins directly at the edge of the air supply opening, so that the lower protective channel opening corresponds to the air supply opening. In this way, the widening of the protective channel can be reduced and the inherently undesirable catching effect of the fuel around the air supply opening can be minimized. This supports efficient cooling of the grate block by a

Reduction of blockages.

In a preferred embodiment, the thickening is in the form of a bead and is thus arched. The arched design of the wall thickening ensures that the items to be fired can be transported unhindered over the grate block, i.e. without tilting due to angular unevenness.

In a preferred embodiment, the air supply channel has a slot-shaped air supply opening which is aligned in the longitudinal direction of the grate block. The width of the air supply opening is selected in such a way that the slag resulting from the combustion of the fuel and the incineration residues fall off anally as little as possible due to the air supply and cause a blockage. Reliable cooling of the grate block can thus be ensured.

In a preferred embodiment, a transition area of the thickening, which extends between the inner flank and the outer flank, is flattened or rounded. This formation of the thickening reduces the risk that the material to be fired is blocked by an angular area of the thickening during transport on the combustion grate and completely or partially blocks the air supply duct. This also supports efficient cooling of the grate block.

The term “cross section” is to be understood below as a section in a plane running at right angles to the support surface. In a preferred embodiment, the inner flank, viewed in cross section, runs at least in a lower region of the inner flank facing the bearing surface, at least approximately at right angles to the bearing surface. This further reduces the widening of the protective channel, so that the catching effect is reduced and ultimately fewer items to be fired can collect in the protective channel. As a result, the air supply through the air supply passage can be improved. The inner flank preferably runs at right angles to the bearing surface at least approximately over the total height of the inner flank. In this embodiment, the free cross section of the protective channel is at least approximately the same as the air supply opening. This minimizes the risk of items to be fired collecting in the protective channel, since the upper protective channel opening defines the narrowest point of the protective channel.

In a preferred embodiment, the cross section of the protective channel is designed to widen, in particular to widen continuously, in the direction from the end of the protective channel facing away from the support surface to the support surface. This design of the protective channel enables the combustion residues that have entered the protective channel to be easily removed. This is because the items to be fired on the grate block are pressed further in the direction of the cooling air side into the protective channel and released because of the widening of the protective channel. A blockage of the air supply can thus be avoided. In a preferred embodiment, the cross section of the air supply channel widens in the direction away from the support surface, in particular continuously. If the material to be fired, in particular slag, should nevertheless enter the air supply duct, this indicates

Embodiment has the advantage that the widening allows the material to be fired to flow away more easily, as already explained in connection with the protective channel. Blockage of the air supply channel can thus be avoided and an efficient air supply, that is to say in particular the efficient cooling of the grate block, can be ensured.

In a preferred embodiment, the cross section of the air supply channel and / or the protective channel widens in the form of a cone, the surface line of the cone forming an angle of 10 degrees to 30 degrees with respect to a direction R running at right angles to the support surface. The angle is preferably 15 degrees. This embodiment has the further advantage that it can be produced easily, in particular in a casting process.

In a preferred embodiment, the outer flank, viewed in cross section, extends, in particular continuously, in the direction from the end region of the thickening facing away from the contact surface to the contact surface, widening. The basic shape of the thickening is reminiscent of a volcano. This shape means that the thickening does not form any significant unevenness on the surface of the grate block, which could act as an obstacle for the material to be fired. In a preferred embodiment, the outer flank, viewed in cross section, runs in a curve. This training supports the drainage of the liquid fraction around the thickening. This reduces the risk that the liquid fraction is partially blocked by the outer flank. Specifically, according to this embodiment, the risk of causing an accumulation of the liquid fraction outside the thickening, which is pushed beyond the thickening by the firing material moving in the transport direction and ultimately into the

Air inlet opening.

The outer flank preferably runs concave or convex at least approximately in the shape of a quarter circle. This shape enables a particularly simple production of the

Thickening.

In a preferred embodiment, the outer flank runs at least approximately in a straight line. This shape also enables a particularly simple production of the thickening, in particular in the case of a casting process.

The outer flank, measured in cross section, preferably forms an angle of 20 degrees to 45 degrees, particularly preferably 30 degrees, to the support surface. This angular range means that the thickening does not form any significant unevenness on the surface of the grate block, which could act as an obstacle for the material to be fired.

In a preferred embodiment, the thickening has essentially the shape of a hollow truncated cone, preferably having an elliptical base. This embodiment offers an optimal design, which at the same time reduces the risk of an accumulation of liquid fraction in the area of the thickening, and enables a simple construction, in particular for series production.

In a preferred embodiment, the thickening, viewed in a plane A running parallel to the support surface, has a U-shape or V-shape, the opening of the U-shape or the V-shape being oriented in the transport direction T. In this embodiment, items to be fired that have accumulated in the protective channel can be pushed further downstream through the opening of the U-shape or the V-shape and conveyed in the direction of transport T by the items to be fired moving in the transport direction. In addition, the thickening allows the liquid fraction located upstream of the U-shaped or V-shaped thickening to flow away laterally around the thickening, viewed in the transport direction T.

In a preferred embodiment, the arms of the U-shape or V-shape of the thickening, viewed in the transport direction T, extend at least as far as an edge of the air supply opening which is located furthest upstream.

In a preferred embodiment, the height of the thickening, measured from the support surface, is 5 mm to 30 mm. This height of the thickening allows an efficient diversion of the liquid fraction around the thickening, so that it does not flow into the air supply channel via the thickening. The height of the thickening is preferably 10 mm, so that in addition the promotion of the The material to be fired is not affected by the amount of thickening. Thus, the thickening does not form any significant unevenness on the surface of the grate block, which could act as an obstacle for the material to be fired. At the same time it is ensured that the thickening is not rubbed off prematurely by the items to be fired. The service life of the grate block can thus be optimized.

In a preferred embodiment, the air supply opening is formed in the section of the upper wall which, viewed in the pushing direction S, protrudes from the end position of a pushing movement of the grate block preceding in the transporting direction T. As a result, air is supplied to the combustion grate or to the combustion bed on the combustion grate, which supports the burnout of the material to be burned.

In a preferred embodiment, the thickening is present as a molded part and the thickening is welded onto the grate block. Thus, a conventional grate block, i.e. a grate block without a thickening, can be equipped with a thickening if necessary. This embodiment thus allows a flexible design of the grate blocks of a combustion grate if only individual grate blocks have to be equipped, for example in one area of the combustion grate.

In a preferred embodiment, the thickening is in the form of a molded part and is mechanically attached to the grate block. This embodiment also enables fastening by a craftsman who has no special qualification in welding. Furthermore, the mechanical fastening is easily detachable and the Thickening can be loosened again without special processing of the block body, for example without grinding the weld seam.

In the present context, mechanical connections include form-fitting and / or force-fitting connections and differ from material connections such as welding.

In a preferred embodiment, the thickening is formed in one piece with the grate block. The term "in one piece" is to be understood in such a way that the thickening and the grate block form a single block, which can be produced, for example, by casting, and there is no seam. Cost-effective production is thus possible. For the sake of completeness, it should be mentioned that a plurality of air supply ducts extending through the upper wall can be provided and provided with a thickening. This also applies to the front wall, which can also have further air supply channels that can be surrounded by a thickening. As a result, an optimal air supply to the combustion grate or to the combustion bed on the combustion grate is obtained, which contributes to a very high burnout of the material to be burned.

According to a further aspect, the present invention also relates to a combustion grate comprising at least one of the grate blocks described above.

Furthermore, the present invention relates to the use of an above-described combustion grate for the incineration of waste as well as a

Waste incineration plant including such

Combustion grate.

Another aspect of the invention relates to a molded part for attachment to an upper wall of a block body of a grate block around an air supply opening formed in the upper wall, which is formed by an air supply channel extending through the upper wall, the grate block being intended for a combustion grate and the Block body is designed as a cast part, the upper wall forming a support surface along which the material to be fired is to be conveyed, the molded part, in the attached state, forming a thickening projecting from the support surface which surrounds the air supply opening, forming a protective channel extending the air supply channel and is intended to prevent liquid from being drawn into the

To prevent air supply opening, wherein the protective channel is surrounded by an inner flank of the thickening, i.e. the molded part, and the thickening has an outer flank adjoining the inner flank and sloping down on the side facing away from the protective channel.

Furthermore, the protective channel of the molded part comprises an upper protective channel opening which, viewed in the attached state of the molded part, is arranged on the side of the molded part facing the item to be fired, ie on the end of the protective channel facing away from the support surface, and a lower protective channel opening located on the side facing away from it . On the side of the molded part facing away from the item to be fired, the molded part has a bottom penetrated by the protective channel, the outer bottom surface of which, when the molded part is attached, runs at least approximately flush with the plane of the support surface

In a preferred embodiment, the molded part is intended to be welded around the air supply opening which is formed in the upper wall of the block body of the grate block. The method for fastening the molded part is thus carried out by welding to the upper wall. It should also be mentioned here that the welding can take place on the side of the upper wall facing the item to be fired or on the side of the upper wall facing away from the item to be fired. This ensures an at least approximately airtight connection between the molded part and the block body, so that air is supplied to the items to be fired in a controlled manner.

In a preferred embodiment, the molded part is mechanically attached to the upper wall of the block body. This embodiment allows simple fastening without any special knowledge of welding. Furthermore, the mechanical fastening is easily detachable and the molded part can be detached again without special processing of the block body, for example without grinding off the weld seam. It is also conceivable to design the molded part in such a way that it is first mechanically fastened by means of a fastening means in a first step and then by welding in a second step. This embodiment has the advantage that the welding can be done particularly efficiently because the molded part is already through the Fastening means is held in its operating position without further aids.

The grate block is intended for a combustion grate and can be designed as a cast part. In a preferred embodiment, the molded part is also designed as a cast part. Such cast molded parts are particularly advantageous from an economic point of view, since they can be produced inexpensively. In addition, a mechanical connection is advantageous in this embodiment because it does not require casting to cast welding.

In a preferred embodiment, the molded part is produced from a different material than the material of the block body. The grate block thus comprises a first material for the block body and a second material, which is different from the first material, for the molded part. A selection of different materials for the block body and for the molded part can take into account different stresses on the block body and the molded part, for example different ones

Wear, different operating temperatures or different training features such as geometry or mechanical properties, to name just a few examples. Furthermore, different production methods can also be considered, so that their production can be optimized independently of one another.

Materials such as steel, corrosion-resistant chrome steel and heat-resistant steel, which, for example, by milling can be processed, are particularly suitable for the molded part. These materials in turn enable the production of more complex geometries of the molded part than is the case with a cast molded part. In a preferred embodiment, the molded part is made of a harder material than the material of the block body. This has the advantage that the maintenance of the grate block can be carried out at longer intervals due to a molded part that is less subject to wear. In a preferred embodiment, the cross section of the protective channel widens in the direction from the upper protective channel opening to the lower protective channel opening, and in particular is designed to widen continuously. As already mentioned above, this design of the protective channel enables the combustion residues that have entered the protective channel to be easily removed.

In a preferred embodiment, the molded part has essentially the shape of a hollow truncated cone, preferably having an elliptical base. This embodiment offers an optimal design which at the same time reduces the risk of an accumulation of liquid fraction in the area of the thickening. In addition, a simple construction, in particular for series production, is made possible. Fastening means, for example a screw, which do not belong to the molded part, are conceivable as fastening means for fastening the molded part. In a preferred embodiment, the molded part comprises the fastening means, which is designed in such a way that the mechanical fastening takes place by means of a form-fitting connection to the upper wall, for example by pressing the molded part into a recess in the upper wall

Wall.

In a preferred embodiment, the molded part comprises the fastening means, which is designed in such a way that the mechanical fastening is carried out by a force-locking connection on the upper wall, for example by

Clamping the molded part in a recess in the upper

Wall.

A combination of these fastening methods is possible.

In a preferred embodiment, the fastening means protrudes in the form of a projection from the bottom of the molded part, in the direction away from the side of the molded part facing the firing material, i.e. in the fastened state in the direction of the grate block. The projection is intended to be at least partially received in the recess and held by a mechanical connection, for example by a form-fitting and / or force-fitting connection.

A form-fitting connection can be produced, for example, in that the projection is introduced into the recess, the recess having a tapering section, ie a narrowing, and the projection having a widening section. The largest cross-section of the widening section is larger than the smallest cross-section of the constriction dimensioned in such a way that the widening section of the projection can be pressed in through the constriction and the projection is thereby held clamped.

In a preferred embodiment, the projection has a thread and the recess has a thread receptacle so that the projection can be screwed into the recess.

Positive and non-positive fastening methods have the advantage that they can be carried out easily and enable a robust fastening of the molded part to the grate block.

If necessary, the projection can enclose and lengthen the protective channel.

The projection is designed such that in the fastened state in which the projection is received in the recess, the protective channel of the molded part and the air supply channel of the block body are flow-connected.

In the fastened state, be it in the welded or mechanically fastened state, the molded part forms a thickening which offers a solution for reducing the risk of impairment of the air supply through the air supply ducts, as explained above in connection with the thickening according to the invention.

In this context, this molded part also allows a flexible design of the grate blocks of a combustion grate, because only individual grate blocks, for example an area of the combustion grate can be equipped.

Furthermore, the molded part can be used to replace a thickening that was previously formed on the grate block and surrounding the air supply opening, preferably according to the above disclosure, if it is worn. This helps to reduce maintenance costs because the entire grate block does not have to be replaced.

If necessary, the molded part can also be used if the air supply opening of the grate block has been damaged by the operation of the combustion grate and the edge of the air supply opening has been worn away in areas, for example. The molded part can be welded or mechanically fastened in such a way that it covers this damaged area so that the grate block can be reinserted.

In a preferred embodiment, the grate block is intended for a combustion grate in which successive grate blocks are arranged one above the other in steps and are designed in such a way that the material to be fired is rearranged and conveyed during combustion by means of pushing movements performed relative to one another. Furthermore, viewed in a thrust direction S oriented essentially parallel to the longitudinal axis L, the foremost end of the bearing surface forms an edge over which the bearing surface drops into a thrust surface formed by a front wall. Furthermore, the front wall has a lower support edge which is arranged in a plane E which runs essentially at right angles to the longitudinal axis L and which is intended for this purpose is to come into contact with the support surface of an adjacent grate block in the thrust direction S.

Another aspect of the invention relates to a method for producing a grate block according to the above disclosure, wherein a) a block body designed as a cast part, having an upper wall and defining a longitudinal axis L is provided, the upper wall forming a support surface along which the material to be fired is conveyed and the front end of which, when viewed in a pushing direction S oriented essentially parallel to the longitudinal axis L, forms an edge over which the support surface drops into a pushing surface formed by a front wall, the front wall a substantially perpendicular to the longitudinal axis L extending plane E, which is intended to come into contact with the bearing surface of an adjacent grate block in the pushing direction S, the upper wall having an air supply opening formed by an air supply channel extending through the upper wall and the bearing surface he is essentially flat around the air supply opening, and b) the thickening is welded or mechanically fastened around the air supply opening.

The flat design of the support surface has the advantage that the thickening sits stably on the grate block before fastening, so that the fastening work is simplified. However, it is also possible to train the To provide support surface around the air supply opening complementary to the geometry of the side of the thickening facing the support surface, for example in order to simplify mechanical fastening. In a preferred embodiment, the thickening is formed by the molded part disclosed above. The grate block thus comprises the block body and the thickening or the molded part.

In this context, the advantages of this method result from the above disclosure relating to the corresponding thickening or the corresponding molded part.

Another aspect of the invention relates to a method for producing a grate block according to the above

Disclosure, wherein a replacement thickening is welded or mechanically fastened to restore the thickening after abrasion of at least 50%, preferably of at least 80% of the height of the thickening caused by the operation of the grate block. The replacement thickening is welded or mechanically fastened around the air supply opening, preferably on the site of the previous thickening. This process enables the grate block to be retrofitted, so there is no need for a new one.

In a preferred embodiment, the replacement thickening is formed by the molded part disclosed above.

The invention is illustrated by means of the attached figures. Of these shows: 1 shows a grate block according to the invention in a perspective view; and

FIG. 2 shows a detail of the grate block according to FIG. 1 in

Longitudinal section through the sectional plane II-II shown in FIG. 1, the thickening being formed in one piece with the grate block;

Fig. 3 shows a section of the grate block according to FIG

Longitudinal section through the section plane II-II shown in FIG. 1, the thickening being welded onto the grate block;

4 shows a detail of a further grate block according to the invention in longitudinal section, with a molded part being mechanically fastened to an upper wall of the grate block; 5 shows a longitudinal section of the molded part according to FIG. 4 without a grate block; and

Fig. 6 is a longitudinal section of the top wall of the

Grate blocks according to FIG. 4 without a molded part.

As can be seen from FIG. 1, the grate block 10 comprises a block body 12 designed as a cast part, which is essentially designed in the form of an elongated parallelepiped with a longitudinal axis L.

The block body 12 comprises an upper wall 14 which forms a support surface 16 running parallel to the longitudinal axis L, along which the material to be fired is to be conveyed and the front end of which, viewed in the pushing direction S, forms an edge 19 over which the support surface 16 in a thrust surface 22 formed by a front wall 20 drops.

In the embodiment shown, the bearing surface has a first bearing surface area 16a and a second bearing surface area 16b, both of which run parallel to the longitudinal axis L, but the first

Support surface area 16a is arranged offset upwards with respect to the second support surface area 16b and is connected to this via a beveled transition 17.

On the side opposite the front wall 20, the block body 12 has a rear wall 24 which is equipped with at least one hook 26 with which the grate block 10 can be suspended in a block holding tube. A central web 29 is also arranged on the underside of the grate block 10 facing away from the support surface 16.

The grate block 10 is closed laterally by a side wall 28a, 28b extending in the longitudinal direction L.

Within the combustion grate, the grate block 10 rests on a grate block following in the thrust direction S. For this purpose, the lowermost area of the front wall 20 is designed in the form of a block 34 which is intended to rest on the support surface of a grate block adjacent in the thrust direction S. The lowermost area including a front support edge 23 of the thrust surface formed by this is in an im Arranged substantially at right angles to the longitudinal axis L extending plane E.

As can be seen from FIG. 2, the upper wall 14 also has an air supply opening 35 which is formed by an air supply channel 38 extending through the upper wall 14. Primary air is supplied to the combustion grate or the combustion bed on the combustion grate through the air supply duct 38.

In the embodiment shown, the air supply duct 38 forms a slot-shaped air supply opening 35 in the upper wall 16, which is aligned in the longitudinal direction of the grate block 10, and the air supply duct 38 defines a longitudinal plane of symmetry P. In FIG. 2, the section plane II-II runs in the longitudinal plane of symmetry P.

The air supply duct 38 extends concentrically to an axis R running at right angles to the support surface 16 and in the longitudinal plane of symmetry P, the clear opening of the air supply duct 38 being essentially elliptical and widening continuously in the direction of the support surface 16 in the form of a cone. The air supply duct 38 comprises a first air supply duct section 38a facing the support surface 16 and a second air supply duct section 38b adjoining the first air supply duct section 38a on its side facing away from the support surface, the expansion of the second air supply duct section 38b being greater than the expansion of the first air supply duct section 38a. With respect to the axis R, the surface line of the cone forms a first angle of 10 degrees in the first Air supply duct section 38a and a second angle of 15 degrees in the second air supply duct section 38b.

Furthermore, the air supply opening 35 is completely surrounded by a thickening 50 protruding from the support surface 16. The thickening 50 forms a protective channel 57 which extends the air supply channel 38 and is intended to prevent liquid from getting into the air supply opening 35.

The protective channel 57 comprises a lower protective channel opening 57a on the end of the protective channel 57 facing the bearing surface 16 and an upper protective channel opening 57b on the end of the protective channel 57 facing away from the bearing surface 16, ie on the side of the thickening facing the firing material. Furthermore, the protective channel 38 is enclosed by an inner flank 54 of the thickening 50, the inner flank 54 being formed directly adjacent to an edge of the air supply opening 58 running in the support surface. In addition, the thickening 50 has an outer flank 55 adjoining the inner flank 54, sloping down on the side facing away from the protective channel 38 and running in a straight line. A flattened transition area 60 of the thickening 50 extends between the inner flank 54 and the outer flank 55. In the embodiment shown, the height h of the thickening, measured from the support surface, is approximately 20 mm. In addition, the inner flank, viewed in cross section, runs at least approximately in the extension of the lateral surface of the first air supply channel section 38a. In FIG. 2, the thickening 50 is formed in one piece with the grate block 10 in a casting process.

In FIG. 3, the grate block according to FIG. 1 is shown, the thickening being formed by a molded part 50 ′ and being welded onto the grate block 10. Accordingly, the grate block 10 has a weld seam 70 at the interface between the molded part 50 'and the

Support surface 16 on. The molded part 50 'has in

Essentially the shape of a truncated cone having an elliptical base and which extends concentrically to the axis R. Furthermore, the molded part 50 ′ comprises a protective channel 57 extending concentrically to the axis R, which is intended to lengthen the air supply channel 38. The protective channel 57 is designed such that its inner flank 54 in the

Extension of the lateral surface of the air supply channel 38 runs.

The other features of the section of the grate block 10 shown in FIG. 3 are similar to those in FIG. 2 and can be taken from the corresponding description.

In operation, the grate blocks 10 by means of

Block holder tubes moved relative to each other. Depending on whether the block holding tubes are assigned to a stationary or a movable grate block, the block holding tubes are either attached to stationary consoles or to consoles which are arranged in a movable grate carriage. It is driven by hydraulic cylinders, which move the grate trolleys back and forth over rollers on corresponding running surfaces.

As a result of the relative movement obtained in this way, the foot 34 of a first grate block 10 is pushed back and forth over the support surface 16 of the respective subsequent grate block 10, the material to be fired being conveyed over the support surface 16 before it over the edge 19 onto the

Support surface 16 of the following grate block 10 is thrown off.

4 shows a section of a grate block 10 according to the invention, the thickening being formed by a molded part 50 ′ and mechanically fastened to the grate block 10. The grate block 10 comprises a block body 12, which has the same structural features as the

Has grate block of FIG. Only the differences are described in more detail below and the same parts are denoted by the same reference symbols.

The block body 12 has a recess 72 extending around the air supply opening 35. In the present case, the air supply opening 35 and the

Recess 72 rotationally symmetrical about a perpendicular to the support surface 16 and through the

Air supply opening 35 defined axis Q formed. The recess 72 has a tapering section, i.e. a constriction, in the form of a lip 74, which connects to the support surface 16.

The molded part 50 ′ essentially has the shape of a hollow, elliptical base Truncated cone, as can be seen in Fig. 4 and Fig. 5. On the side of the molded part facing away from the item to be fired, the molded part has a bottom 80 penetrated by the air supply channel, the outer bottom surface 82 of which coincides with the base surface of the truncated cone. In the embodiment shown in FIG. 4, in the fastened state of the molded part, the outer bottom surface 82 runs at least flush with the plane of the support surface 16.

Furthermore, the molded part 50 ′ comprises a fastening means in the form of a projection 84, which protrudes from the base 80 of the molded part, in the direction away from the side of the molded part facing the material to be fired. The projection 84 is frustoconical and rotationally symmetrical to the axis Q. The projection 84 is intended to be received in the recess 72 and held by a mechanical connection.

For this purpose, the largest cross section of the widening section of the projection 84 is larger than the smallest cross section of the constriction 74, in such a way that the projection 84 can be pressed into the recess 72 and inserted. As a result, the projection 84 remains clamped in the recess 72.

Reference character list

Grate block 10

Block body 12

top wall 14

Support surface 16

Support surface area 16a, 16b

Transition 17

Margin 19

front wall 20

back wall 24

Hook 26

Side wall 28a, 28b

Central bar 29

Block 34

Air inlet port 35

Air supply duct 38

First and second air supply duct section 38a, 38b thickening or molded part 50, 50 '

inner flank 54

outer flank 55 Protection channel 57

lower and upper protective channel opening 57a or 57b edge of air supply opening 58

Transition area 60

Weld seam 70

Front wall level E.

Longitudinal axis L.

Thrust direction S

Longitudinal plane of symmetry P

Axis r

Amount of thickening h

Recess 72

Lip 74

Floor 80

Floor area 82

Ledge 84

Axis Q

Claims

1. Grate block (10) for a combustion grate, the grate block (10) comprising a block body (12) having an upper wall (14) and defining a longitudinal axis L, the upper wall (14) forming a support surface (16) along which the material to be fired is to be conveyed and whose frontmost end, viewed in a pushing direction S oriented essentially parallel to the longitudinal axis L, forms an edge (19) over which the support surface (16) into a pushing surface formed by a front wall (20) ( 22), the front wall (20) has a lower support edge (23) which is arranged in a plane E which runs essentially at right angles to the longitudinal axis L and is intended to come into contact with the support surface of a grate block adjacent in the thrust direction S, wherein the upper wall (14) has an air supply opening (35) formed by an air supply channel (38) extending through the upper wall (14), characterized in that

the air supply opening (35) is at least partially surrounded by a thickening (50) protruding from the support surface (16), which forms a protective channel (57) which extends the air supply channel (38) and is intended to prevent liquid from flowing into the air supply opening (35 ), the protective channel (57) being enclosed by an inner flank (54) of the thickening (50) and the thickening (50) has an outer flank (55) adjoining the inner flank (54) and sloping down on the side facing away from the protective channel (57).

2. Grate block according to claim 1, characterized in that the inner flank (54) is formed adjacent, preferably directly adjacent to an edge (52) of the air supply opening (35) formed in the support surface (16).

3. Grate block according to claim 1 or 2, characterized in that the cross section of the protective channel (57) in the direction of the end of the protective channel (57) facing away from the support surface (16)

Support surface (16) is designed to widen, in particular to widen continuously.

4. Grate block according to one of claims 1 to 3, characterized in that the cross section of the air supply channel (38) widens in the direction of the support surface (16) away, in particular widens continuously.

5. Grate block according to one of claims 1 to 4, characterized in that the thickening (50) essentially has the shape of a hollow truncated cone, preferably having an elliptical base.

6. Grate block according to one of claims 1 to 5, characterized in that the thickening (50) in a plane A running parallel to the support surface (16) considered, has a U-shape or V-shape, the opening of the U-shape or the V-shape being oriented in the transport direction T.

7. grate block according to one of claims 1 to 6, characterized in that the thickening (50) on the

Grate block is welded on or mechanically attached.

8. Grate block according to one of claims 1 to 6, characterized in that the thickening (50) is formed in one piece with the grate block.

9. Combustion grate comprising at least one grate block

(10) according to one of the preceding claims.

10. Use of a combustion grate according to claim 9 for incinerating waste.

11. Waste incineration plant comprising a

Combustion grate according to claim 9.

12. The method for producing a grate block (10) according to one of claims 1 to 7, characterized in that a) an upper wall designed as a cast part

(14) having block body (12) defining a longitudinal axis L is provided, the upper wall (14) forming a support surface (16) along which the material to be fired is to be conveyed and its pushing direction, which is essentially parallel to the longitudinal axis L S considered, the front end forms an edge (19) over which the Support surface (16) drops into a pushing surface (22) formed by a front wall (20), the front wall (20) has a lower support edge (23) which is arranged in a plane E substantially at right angles to the longitudinal axis L and which is intended for this purpose is to come into contact with the support surface of an adjacent grate block in the thrust direction S, the upper wall (14) having an air supply opening (35) formed by an air supply channel (38) extending through the upper wall (14) and the bearing surface (16) is essentially flat around the air supply opening (35), and b) the thickening is welded or mechanically fastened around the air supply opening (35).

13. A method for producing a grate block (10) according to any one of claims 1 to 8, characterized in that a replacement thickening after an abrasion of at least 50%, preferably of at least 80% of the height of the thickening caused by the operation of the grate block (10) to

Restoration of the thickening is welded or mechanically attached.

14. Molded part for attachment to an upper wall (14) of a block body (12) of a grate block around an air supply opening (35) formed in the upper wall, which is formed by an air supply channel (38) extending through the upper wall (14), wherein the grate block is intended for a combustion grate and the block body (12) as a cast part is formed, wherein the upper wall (14) forms a support surface (16) along which the material to be fired is to be conveyed, wherein the molded part, in the attached state, forms a thickening (50) protruding from the support surface (16), which the

Air supply opening (35) surrounds one the

Air supply channel (38) forms the lengthening protective channel (57) and is intended to prevent liquid from getting into the air supply opening (35), the protective channel (57) being enclosed by an inner flank (54) of the thickening (50) and the Thickening (50) has an outer flank (55) adjoining the inner flank (54) and sloping on the side facing away from the protective channel (57).

15. Molding according to claim 14, characterized in that the cross section of the protective channel (57) widens in the direction from the end of the protective channel (57) facing away from the bearing surface (16) to the bearing surface (16), and in particular is designed to widen continuously.

16. Molding according to claim 14 or 15, characterized by essentially the shape of a hollow truncated cone, preferably having an elliptical base.

17. Molding according to one of claims 14 to 16, characterized by a fastening means for mechanical fastening to the upper wall (14).