DK2306086T3 - Gratings Tang - Google Patents

Description

Grate bar

The present invention concerns a grate bar for arranging in a grate of an incineration plant serving for burning kiln feed according to the preamble of claim 1.

One major component of an incineration plant, such as for example a residual material incineration plant for the thermal disposal of waste, is a combustion grate. Kiln feed travels from a first end to a second end on such a combustion grate, arranged horizontally or inclined within an incineration plant, wherein the first end is the loading point for the kiln feed and the second end is normally known as the external grate, on which the thermal conversion of the kiln feed is completed. Combustion grates are normally constructed from a multitude of individual grate bars these days, which are joined to form a corresponding combustion grate. This construction allows the easy replacement of individual grate bars if individual areas of the grate are damaged.

The grate bars are normally set in rows next to each other for transporting the kiln feed across the grate or for forming a diagonal plane, across which the kiln feed travels, wherein the rows are arranged in steps above each other, so that the rows partially overlap. Individual rows can normally be displaced in relation to each other to enable a transport of the kiln feed by displacing the overlapping grate bar rows in relation to each other.

Grate bars used in such incineration plants and the grates formed from the same must firstly have sufficient mechanical stability to be able to receive and transport the kiln feed, and must secondly also have suitable high temperature resistance to be able to resist the temperatures that occur during the thermal conversion of the kiln feed. WO 96/29544 A1 discloses grate bars that form a chamber through which water can flow under the surface forming the grate layer, so that these grate bars are firstly water-cooled, but secondly also air-cooled by combustion air flowing in from the bottom. The combustion air enters at the side through gaps formed and remaining between two neighbouring grate bars. A grate bar through which combustion air flows in from below, which then exits via outlet openings at the top of the grate bar, is known from DE 195 28 310 Al. In order to be able to adequately cool this grate bar it is also equipped with corresponding cooling channels, through which a coolant flows. EP 0 126 264 Al and EP 0 165 432 Al disclose an air-cooled grate bar.

An air stream flows towards the grate bars or grates from below to supply combustion air to the kiln feed and the latter have outlet openings, through which the incoming combustion air can enter the kiln feed. Such grates or grate bars are for example known from DE 20111804 U1. European patent document EP 1 612 483 B1 also discloses a corresponding grate bar for use in incineration plants, towards which an air stream flows from below, wherein the grate bars shown here have air guide channels, via which the air stream arriving from below is guided through the combustion grate in such a way that it exits on the longitudinal side of the grate bar lying in advancement direction, and flows into the kiln feed there.

One problem when using a grate or grate bars in incineration plants is the high temperature corrosion that occurs there. High temperature corrosion is a phenomenon that is similar to the damage profile of wet corrosion, although corrosion is not caused by aqueous media in this case but often through a reaction of the material with the kiln feed or the gaseous compounds generated during combustion. Halogenide containing salts for example lead to the formation of volatile halogenides under the conditions prevailing in incineration plants, which attack the protective oxide layer formed on the material and thus lead to corrosion of the material. Nitrogen contained in the fuel as well as in combustion air can diffuse into the material under the conditions prevailing in the incineration plant, and in particular on the grate, and can affect the mechanical stability of the material by forming metal nitrides in such a way there that the onward transport of the kiln feed will lead to increased abrasive wear of the grate bars.

The wear caused by this necessitates the replacement of grate bars or grates at regular or irregular intervals in order to be able to ensure the functional safety of the grate bars. The incineration plant will however need shutting and cooling down for replacing the grate bars, which is accompanied by substantial downtimes of the overall plant. These downtimes lead to economic disadvantages, which must be avoided. In addition incineration plants, such as in particular waste incineration plants, often display optical combustion features only in a stationary condition, wherein unfavourable combustion conditions can occur during the start-up and shutting down times of the incineration plant, during which contaminants are increasing generated. Although these are collected by downstream filter systems this leads to an increased load being placed on such systems. This in turn results in earlier maintenance of the filter systems becoming necessary.

It is therefore the object of the present invention to extend the working life of the grate bars used in incineration plants.

With an air-cooled grate bar of the type described in more detail above this object is solved according to the invention in that the first wear plate is arranged below the first curved section lying above the same in an arrangement below the same that prevents a falling through of kiln feed into the area below the grate bar when the first curved section has rusted through, and in that an outlet opening through which combustion air flows in from the bottom is formed on the top.

It has been found that high temperature corrosion phenomena increasingly occur in particular in the area of the first curved section that connects the top of a grate bar with its facing side, so that more signs of wear are generated here. Surprisingly it has been discovered that arranging a first wear plate below this first curved section will continue to ensure the functional safety of the grate bar in a case of corrosion of the material forming the first curved section. The front section of the grate bar is firstly mechanically stabilised by inserting the first wear plate, so that sufficient overall mechanical stability is given even if the first curved section is corroded, whilst the first wear plate secondly itself prevents kiln feed from reaching the area below the grate bar if the first curved section has rusted through.

The first wear plate to be envisaged according to the invention is spaced apart from the first curved section and arranged on the inside of the grate bar.

One grate bar according to the invention has an outlet opening for gaseous media, such as for example combustion air, directed against the underside at the top. Combustion air passes from the area below the grate bar through this opening and into the kiln feed located on the grate bar. In this way combustion air is guided into the kiln feed in a way that ensures an adequate supply of the combustion process with combustion air.

In a further development of the invention a second wear plate is arranged below the second curved section that transforms into the rear longitudinal surface or the diagonal at a distance from the second curved section lying above the same. The second wear plate is arranged at a distance from the second curved section lying above the same here.

The wear plates to be envisaged according to the invention can be fitted to a central rib of the grate bar or formed on the same. In a preferred design of the grate bar according to the invention the same is formed as a single piece, so that the first and second wear plates are formed on a central rib of the grate bar. The single-piece design of the grate bar can for example be cast from a suitable material for this purpose.

The previously mentioned central rib can have support bridges or cooling bridges in a grate bar according to the invention, via which the central rib is supported against the top of the grate bar. The support bridges or cooling bridges can also fulfil air guiding functions and ensure a guiding of the air stream supplied from below against the grate bar to the outlet opening arranged at the top of the grate bar. A grate bar according to the invention can have recesses, in particular in the area of the central rib, via which several grate bars can be connected with each other, for connecting several grate bars accordingly to form one grate. Connection bridges that can be inserted into the recesses are for example suitable as connection means. A grate bar according to the invention can have a support part for fitting to the ground, with which it can be positioned on a holding bar. The holding bar simultaneously serves as a rotation bearing, around which a rotation of the grate bar is made possible when individual grate bars lying above each other and forming grate sections are displaced. In one particular design of the grate bar according to the invention the same has a support part in the front area of the grate bar as well as in the read area. This enables a turning of the grate bar in a case where corrosion signs are excessive in the area of the front first curved section, so that the rear second section of the grate bar becomes a front section. This doubles the working life of the individual grate bar.

In one particular design of the grate bar, the same is designed mirror-symmetrically to a mirror plane extending transverse to a longitudinal expansion of the grate bar for this purpose.

In a further design of the grate bar according to the invention the first and second wear plates are formed from a material that is different from the rest of the material of the grate bar. The material of the wear plates in particular has a higher high temperature corrosion resistance than the material of the rest of the grate bar. With such a design the wear plates are fitted to the grate bar with suitable fitting means such as for example welding, screwing and suchlike, or also with clamping jaws. For this the grate bar can have recesses in a central rib that correspond to the shape of the wear plates, into which a wear plate is pushed and clamped there in a suitable way.

The invention is explained in more detail below with reference to Figures.

Fig. 1 shows a cross-section through a grate bar according to the invention.

Fig. 2 shows a cross-section through a further design of a grate bar according to the invention.

Fig. 3 shows a grate bar according to the invention with two support parts.

Fig. 1 shows a grate bar 1 according to the invention with a top 2, a facing side 3, a rear longitudinal surface 4 and an underside 5. The top 2 and facing side 3 on the one hand, and the top 2 and the rear longitudinal surface 4 on the other transform into each other via a first or a second curved section 6, 8. An outlet opening 10 for gaseous media, such as for example a combustion air stream, directed from the underside 5 against the grate bar 1 according to the invention is located on the top 2. The grate bar 1 according to the invention can have a central rib 11, which is supported against the top 2 by support bridges or cooling bridges 12. The central rib 11 can have recesses 13, into which connection means, such as for example connection rods, can be inserted, so that several grate bars 1 according to the invention can be joined together to form a grate. A first wear plate 7 is arranged on the central rib 11. The first wear plate 7 is arranged at a distance from the first curved section 6 and can have support bridges 17, with which it supports itself against the central rib 11. The grate bar 1 according to the invention also has a support part 14, with which it lies on a support rod 18. The grate bar 1 according to the invention can be arranged to overlap neighbouring grate bars in a grate, wherein it lies on the top of a grate bar neighbouring its facing side 3 with a foot 15.

Fig. 2 shows a design of a grate bar 1 according to the invention, also with a top 2, a facing side 3, a rear longitudinal surface 4 and an underside 5. The construction of the grate bar shown in Fig. 2 substantially equals the construction of the grate bar shown in Fig. 1. The grate bar shown in Fig. 2 does however have a passage 16 below the outlet opening 10 and adjacent to the first wear plate 7, via which combustion air streaming in from the underside 5 can reach an overflow channel 19 before it exits through the outlet opening on the top of the grate bar 1 according to the invention and enters the kiln feed. The overflow channel 19 begins in the area of the foot 15 and ends in the area of the end of the outlet opening 10 arranged on the top 2 in the present embodiment. Apart from the passage 16 the combustion air supplied from the underside 5 can also enter the space 20 above the foot 15 and travel from there to the outlet opening 10 via the overflow channel 19. In this way the first curved section 6 can be cooled by means of the air stream prevailing in the overflow channel 19, which can reduce the high temperature corrosion occurring on the surface of the first curved section 6. This leads to a further extension of the working life of the grate bar 1 according to the invention.

Fig. 3 shows an embodiment of a grate bar 1 according to the invention, both sides of which are designed to be laid onto a support rod. The grate bar shown in Fig. 3 also has a top 2, an underside 5, a facing side 3 and a rear longitudinal surface 4, wherein facing side 3 and rear longitudinal surface 4 are formed mirror-symmetrical to each other. The same applies for the first and second curved sections 6 and 8, via which the top transforms into the facing side 3 or the rear longitudinal surface 4. A first or a second wear plate 7, 9 is arranged below the first and second curved sections 6, 8, with the former being positioned at a distance from the first and second curved sections 6, 8 lying above the same. In the embodiment example shown the first and second wear plates 7, 9 are formed on a central rib 11. The central rib 11 also has recesses 13, into which connection means can be inserted in order to join several grate bars 1 to form a grate. In addition the central rib 11 has support bridges or cooling bridges 12, with which it is supported against the top 2. An outlet opening 10 is arranged in the central area of the grate bar at the top 2, via which combustion air streaming in from the underside 5 can exit and reach the kiln feed lying on the top. Combustion bars 1 according to the invention are arranged in relation to each other in an incineration plant in such a way that the support part 21 comes to lie on a support rod, whilst the foot 15 comes to he on the top of a neighbouring grate bar neighbouring the facing side 3. In this way the second curved section 8 of the neighbouring grate bar is covered and not exposed to high temperature corrosion. In a case of corrosion damage in the area of the first curved section 6 the first wear plate 7 can now firstly ensure that the functionality of the grate bar 1 remains intact. Following this the grate bar 1 can be turned around, so that the first curved section 6 that is attacked by corrosion comes to lie in the rear area of the grate bar 1 and the latter is laid on a support rod via the support part 14. The grate bar neighbouring the first curved section attacked by corrosion the shields the attacked area of the grate bar 1 and is not exposed to further high temperature corrosion. This will increase the working life of the grate bar according to the invention even further.

List of reference numbers: 1 Grate bar 2 Top 3 Facing side 4 Rear longitudinal side 5 Underside 6 First curved section 7 First wear plate 8 Second curved section 9 Second wear plate 10 Outlet opening 11 Central rib 12 Support bridge / cooling bridge 13 Recess 14, 21 Support part 15,22 Foot 16 Passage 17 Support bridge 18 Support rod 19 Overflow channel 20 Space above foot

Claims (9)

1. Luftkølet ristestang (1) til placering i en rist i et forbrændingsanlæg, der tjener til forbrænding af brændbart materiale, med en overside (2), der via et første bueafsnit (6) går over i en frontflade (3) og via et andet bueafsnit (8) eller diagonaler går over i en bageste langsgående flade (4), med en udstrømningsåbning (10) til nedefra tilstrømmende forbrændingsluft, med en underside (5), med en fod (15), der har en støtteflade, og i det mindste en første slidplade (7) placeret under det første bueafsnit (6), der går over i frontfladen (3), med afstand til det over den liggende første bueafsnit (6), hvor foden (15) under dannelse af et derover liggende, for nedefra tilstrømmende forbrændingsluft tilgængeligt rum (20) er placeret på frontfladen (3), kendetegnet ved, at den første slidplade (7) er placeret i et arrangement under det over den liggende første bueafsnit (6), der ved gennemrustet første bueafsnit (6) forhindrer, at brændbart materiale falder igennem i området under ristestangen (1), og at udstrømningsåbningen (10), der lader fra undersiden (5) tilstrømmende forbrændingsluft slippe igennem, er udformet på oversiden (2).An air-cooled grate bar (1) for placement in a grate in a combustion plant serving combustible material, with an upper side (2) which, via a first arc section (6), enters a front surface (3) and via a a second arc section (8) or diagonals enters a trailing longitudinal surface (4), with a downstream orifice (10) flowing downstream, with a bottom (5), with a foot (15) having a supporting surface, and in at least one first wear plate (7) located below the first arc section (6) extending into the front surface (3), spaced from the first arc section (6) above, the foot (15) forming an overlying , a space (20) accessible from below for combustion air is located on the front surface (3), characterized in that the first wear plate (7) is arranged in an arrangement below the above-mentioned first arc section (6), which at the equipped first arc section ( 6) Prevents flammable material from falling into through in the area below the grate bar (1), and that the outlet opening (10) which permits the combustion air flowing from the underside (5) to pass through is formed on the upper side (2). 2. Ristestang ifølge krav 1, hvor en anden slidplade (9) er placeret under det andet bueafsnit, der går over i den bageste langsgående flade (4), eller under diagonalerne (8) med afstand til det over den liggende andet bueafsnit (8).A grating bar according to claim 1, wherein a second wear plate (9) is located below the second arc section extending into the trailing longitudinal surface (4) or below the diagonals (8) spaced from the second arc section (8). ). 3. Ristestang ifølge krav 2, hvor den anden slidplade (9) er placeret med afstand til det over den liggende andet bueafsnit (8).A grating bar according to claim 2, wherein the second wear plate (9) is spaced apart from the second arc section (8). 4. Ristestang ifølge krav 2 eller 3, hvor denne udviser en midterribbe (11), der er forbundet med oversiden (2), og hvorpå den første og anden slidplade (7, 9) er fastgjort eller dannet.A grating bar according to claim 2 or 3, wherein it has a center rib (11) connected to the upper side (2) and on which the first and second wear plate (7, 9) are attached or formed. 5. Ristestang ifølge krav 4, hvor denne udviser støttebroer (12), via hvilke midterribben (11) er støttet mod oversiden (2).A grating bar according to claim 4, wherein it exhibits support bridges (12) through which the center rib (11) is supported against the upper side (2). 6. Ristestang ifølge et af kravene 4 eller 5, hvor midterribben (11) udviser mindst en recess (13), hvori et forbindelsesorgan, især en forbindelsesstang, kan indføres til forbindelse af to ved siden af hinanden placerede ristestænger.A grating rod according to any one of claims 4 or 5, wherein the center rib (11) has at least one recess (13) in which a connecting member, in particular a connecting rod, can be inserted for connection of two adjacent grating bars. 7. Ristestang ifølge et af de foregående krav, hvor denne udviser i det mindste et støtteparti (14), hvormed ristestangen (1) kan lægges på en støttestang (18).A grating rod according to any one of the preceding claims, wherein it has at least one supporting portion (14) with which the grating rod (1) can be mounted on a support rod (18). 8. Ristestang ifølge et af de foregående krav, hvor denne er dannet i et stykke.A grating rod according to any one of the preceding claims, wherein it is formed in one piece. 9. Ristestang ifølge et af kravene 1 til 7, hvor den første og anden slidplade (7, 9) har en højere korrosionsbestandighed mod højtemperaturkorrosion end det over den liggende første eller andet bueafsnit (6, 8).A grating bar according to any one of claims 1 to 7, wherein the first and second wear plates (7, 9) have a higher corrosion resistance to high temperature corrosion than that of the first or second arc section (6, 8).