EP2306086B1 - Grate bar - Google Patents

Description

The present invention relates to a grate bar for arrangement in a grate of a combustion plant serving for the combustion of combustible material according to the preamble of claim 1.

An important component of a combustion plant, such as a waste incineration plant for the thermal utilization of waste, is a combustion grate. On such a combustion grate arranged horizontally or inclined in an incinerator, the combustible material travels from a first end to a second end, the first end being the feedstock for the kiln and the second end typically being referred to as a burnout grate on which the thermal conversion of the fuel finds its completion. Combustion grates are nowadays usually constructed from a plurality of individual grate bars, which are joined together to form a corresponding combustion grate. This structure allows for easy replacement of individual grate bars in case of damage to individual areas of the grate.

For transporting the burning material over the grate or for forming an inclined plane over which the combustion material passes, the grate bars are usually set in rows next to each other, wherein the rows are arranged one above the other like a step, so that the rows partially overlap. Usually, the individual rows are mutually displaceable to allow a transport of the fuel by a displacement of the overlapping grate bar rows against each other.

The grate bars used in such incinerators and the gratings formed from these must on the one hand have sufficient mechanical stability in order to receive and transport the kiln, on the other hand, they must also have a suitable high temperature resistance to the occurring during the thermal conversion of the combustible material To be able to withstand temperatures.

The WO 96/29544 A1 discloses grate bars which form a water-flowable chamber below the surface forming the grate coating, so that these grate bars are on the one hand water-cooled, but on the other hand are also air-cooled by combustion air flowing in from below. The combustion air exits laterally from between two adjacent grate bars formed and remaining column.

From the DE 195 28 310 A1 a grate bar is known, flows through the inflowing from below combustion air, which then exits through outlet openings at the top of the grate bar. To be able to cool this grate bar sufficiently, this is also equipped with corresponding cooling channels, which are traversed by a cooling liquid.

An air-cooled grate bar reveal the EP 0 126 264 A1 and the EP 0 165 432 A1 ,

For supplying combustion air into the kiln, the grate bars or grates are flown from an underside with an air flow and have outlet openings, through which the incoming combustion air can pass into the kiln. Such grates or grate bars are for example from the DE 20111804 U1 known. Also the European patent specification EP 1 612 483 B1 discloses a corresponding grate bar for use in incinerators, which is flown from an underside with an air flow, wherein the grate bars shown here have air ducts over which the stream of air flowed from below is passed through the combustion grate that he at the lying in the feed direction longitudinal side of Roststabes exit and there flows into the kiln.

A problem with the use of rust or grate bars in incinerators is the high-temperature corrosion occurring there. High-temperature corrosion is a phenomenon similar to that of wet corrosion, but in this case corrosion is not caused by aqueous media but rather by reactions of the material with the kiln or combustion gaseous compounds. For example, halide-containing salts under the conditions prevailing in incinerators lead to the formation of volatile halides which attack the protective oxide layer formed on the material and thus lead to corrosion of the materials. Nitrogen contained in the fuel as well as in the combustion air can diffuse under the conditions prevailing in the incinerator and in particular on the grate conditions in the material and there affect the mechanical stability of the material through the formation of metal nitrides such that it by the further transport of the fuel to a reinforced abrasive wear of the grate bars comes.

Due to the resulting wear, it is necessary to replace the grate bars or grates at regular or irregular intervals in order to ensure the reliability of the grate bars. To replace the grate bars, however, the incinerator must be shut down and cool, which is associated with significant dead times of the entire system. These dead times lead to economic disadvantages, which must be avoided. In addition, incineration plants, such as in particular incineration plants, often only in the stationary state an optimal combustion behavior, during the time of startup and shutdown of the incinerator inconvenient combustion conditions may occur in which increasingly pollutants. Although these are intercepted by the downstream filter systems, but this leads to an increased load on these systems. This in turn requires earlier maintenance of the filter systems.

It is therefore the object of the present invention to extend the service life of the grate bars used in incinerators.

In an air-cooled grate bar of the type described in more detail, this object is achieved according to the invention that the first wear plate in durchgerostetem first arc section falling through of firing in the Area below the grate bar preventing arrangement is disposed below the lying above her first arc portion, and that on the upper side for an inflowing from the bottom of the combustion air permeable outlet opening is formed.

It has been found that, especially in the area of the first curved section, which connects the upper side of a grate bar with its end face, high-temperature corrosion phenomena increasingly occur, so that increased wear occurs here. Surprisingly, it has been found that the functional reliability of the grate bar is still ensured by arranging a first wear plate below this first arc section in the case of corrosion of the material forming the first arc section. On the one hand, the front portion of the grate bar is mechanically stabilized by the introduced first wear plate, so that even with corrosion of the first arc section is given a sufficient mechanical stability, on the other hand prevents the first wear plate, even in the case of the first arc section, the burned material not in reach the area below the grate bar.

The inventively provided first wear plate is spaced from the first arc portion disposed on the inside of the grate bar.

An inventive grate bar has on its upper side an outlet opening for directed against the bottom gaseous media, such as combustion air on. Through this opening, the combustion air passes from the area below the grate bar in the firing rod located on the grate bar. As a result, combustion air is passed into the kiln in such a way that a sufficient supply of the combustion process with combustion air is ensured.

In a further development of the invention, a second wear plate is arranged below the second arc section passing over the rear longitudinal surface or the bevels spaced from the second arc section lying above it. Here, the second wear plate is spaced from the above her arranged lying second arc section.

The inventively provided wear plates may be attached to a central rib of the grate bar or be formed on this. In a preferred embodiment of the grate bar according to the invention, this is integrally formed, so that the first and second wear plate are integrally formed on a central rib of the grate bar. For one-piece design of the grate bar this can be cast, for example, from a suitable material.

The above-mentioned center rib may comprise support webs or cooling webs in a grate bar according to the invention, via which the center rib is supported relative to the upper side of the grate bar. In addition, the support webs or cooling webs can fulfill air-conducting functions and ensure guidance of the air flow directed from below against the grate bar to the outlet opening arranged at the top of the grate bar.

For connecting a plurality of grate bars according to the invention to a grate, a grate bar according to the invention can have recesses, in particular in the region of the center rib, via which a plurality of grate bars can be connected to one another. As connecting means, for example connecting webs are suitable, which are insertable into the recesses.

For basic fastening, a grate bar according to the invention can have a support section with which it can be placed on a holding bar. The support rod serves at the same time as a pivot bearing, around which a rotation of the grate bar is made possible when moving superposed, individual grate sections forming grate bars. In a particular embodiment of the grate bar according to the invention, this has a support section both in the front region of the grate bar and in the rear region. This makes it possible to turn over the grate bar in case of too large corrosion phenomena in the region of the front first arc section and so make the rear second portion of the grate bar to a front portion. This doubles the service life of the individual Grate bar.

In a particular embodiment of the grate bar this is designed mirror-symmetrically for this purpose to a transversely to the longitudinal extent of the grate bar mirror plane.

In a further embodiment of the grate bar according to the invention, the first and second wear plate are formed from a different material from the rest of the material of the grate bar. In particular, the material of the wear plates on a higher high temperature corrosion resistance, as the material of the rest of the grate bar. In such an embodiment, the wear plates are attached to the grate bar by suitable fastening means such as welding, screwing and the like or via a press fit. For this purpose, the grate bar in a central rib may have a shape corresponding to the wear plates corresponding recess, in which a wear plate is inserted and clamped there in a suitable manner.

Fig. 1

zeigt einen Querschnitt durch einen erfindungsgemäßen Roststab.

Fig. 2

zeigt einen Querschnitt durch eine weitere Ausgestaltung eines erfindungsgemäßen Roststabs.

Fig. 3

zeigt einen erfindungsgemäßen Roststab mit zwei Auflagepartien.

The invention is explained in more detail 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 embodiment 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, an end face 3, a rear longitudinal surface 4 and a bottom 5. Top 2 and end face 3 on the one hand and top 2 and rear longitudinal face 4 on the other hand via a first or a second arc section 6, 8 into each other , On the top 2 there is an outlet opening 10 for directed from the bottom 5 ago against the grate bar 1 according to the invention gaseous media, such as a combustion air flow. The grate bar 1 according to the invention may have a central rib 11 which is supported by support webs or cooling webs 12 with respect to the upper side 2. The center rib 11 may have recesses 13 into which connecting means, for example, as connecting rods are insertable, whereby a plurality of grate bars 1 according to the invention can be combined to form a grate. At the center rib 11, a first wear plate 7 is arranged. The first wear plate 7 is spaced from the first arc section 6 and may have support webs 17, via which it is supported relative to the center rib 11. Furthermore, the grate bar 1 according to the invention has a support part 14 with which it rests on a support rod 18. The grate bar 1 according to the invention can be arranged in a grid overlapping to adjacent grate bars, wherein it rests with a foot 15 on the top of a grate bar adjacent to its end face 3.

Fig. 2 shows an embodiment of a grate bar 1 according to the invention, also with a top 2, an end face 3, a rear longitudinal face 4 and a bottom 5. Der Aufbau des in Fig. 2 shown grate bar corresponds essentially to the structure of the grate bar, as in Fig. 1 is shown. The in Fig. 2 However, shown grate bar has, below the outlet opening 10 and adjacent to the first wear plate 7, a passage 16 through which the combustion air flowed from the bottom 5 can pass into a transfer port 19 before it exits through the outlet opening on the top of the grate bar 1 according to the invention and in the kiln gets. The overflow channel 19 begins in the region of the foot 15 and terminates in the present embodiment in the region of the end of the arranged on the upper side 2 outlet opening 10. In addition to the passage 16, the brought up from the bottom 5 combustion air can also get into the space 20 above the foot 15 and from there via the overflow channel 19 to the outlet opening 10. As a result, the first arc section 6 can be cooled by means of the air flow prevailing in the overflow channel 19, whereby the occurring at the surface of the first arc section 6 high-temperature corrosion can be reduced. This leads to a further extension of the service life of the grate bar 1 according to the invention.

Fig. 3 shows an embodiment of a grate bar 1 according to the invention, which is designed for double-sided support on a support rod. The in Fig. 3 shown grate bar also has a top 2, a bottom 5, an end face 3 and a rear longitudinal surface 4, wherein end face 3 and rear longitudinal surface 4 are mirror-symmetrical to each other. The same applies to the first and second arc sections 6 and 8, over which the upper side merges into the end face 3 and the rear longitudinal face 4. Below the first and second arc sections 6, 8, a first or a second wear plates 7, 9 are arranged, which are spaced apart from the overlying first and second arc sections 6, 8. In the embodiment shown, the first and second wear plates 7, 9 are integrally formed on a central rib 11. The center rib 11 also has recesses 13, in which connecting means are insertable to assemble a plurality of grate bars 1 to a grid. In addition, the center rib 11 has support webs or cooling webs 12, via which it is supported relative to the upper side 2. In the central region of the grate bar, an outlet opening 10 is arranged on the upper side 2, via which escape from the underside 5 of incoming combustion air and can get into the lying on top of the kiln. In a combustion system, combustion rods 1 according to the invention are arranged relative to one another in such a way that the support part 21 comes to rest on a support rod, while the foot 15 comes to rest on the upper side of a grate rod adjacent to the end surface 3. As a result, the second arc section 8 of the adjacent grate bar is hidden and is thus not exposed to high-temperature corrosion. In the case of corrosion damage in the region of the first arc section 6, the first wear plate 7 can now first ensure that the functionality of the grate bar 1 is maintained. In the further course of the grate bar 1 can be reversed, so that the corrosively attacked first arc section 6 comes to rest in the rear region of the grate bar 1 and this is placed on the support section 14 on a support rod. By then adjacent to corrosive attacked first arc section grate bar the attacked area of the grate bar 1 is shielded and is not exposed to any further high-temperature corrosion. As a result, the service life of the grate bar according to the invention can be further increased.

LIST OF REFERENCE NUMBERS

1

grate bar

2

top

3

face

4

rear longitudinal surface

5

bottom

6

first arc section

7

first wear plate

8th

second arc section

9

second wear plate

10

outlet opening

11

midrib

12

Support web / cooling dock

13

recess

14, 21

edition game

15, 22

foot

16

passage

17

supporting web

18

support pole

19

overflow

20

Room over foot

Claims (9)

1. Air-cooled grate bar (1) for arranging in a grate serving for burning kiln feed in an incineration plant, with a top (2) transforming into the facing side (3) via a first curved section (6) and into a rear longitudinal surface (4) via a second curved section (8) or a diagonal, with an outlet opening (10) for combustion air streaming in from below, with an underside (5), with a foot (15) having a support surface and at least one first wear plate (7) with a first curved section (6) lying above the same, arranged below the first curved section (6) transforming into the facing side (3),
   wherein the foot (15) is arranged on the facing side (3) whilst forming a space (20) lying above the same and accessible for combustion air streaming in from below, characterised in that
   the first wear plate (7) is arranged below the first curved section (6) lying above the same in an arrangement that prevents kiln feed from falling through into the area below the grate bar (1) when the first curved section (6) has rusted through, and in that the outlet opening (10) letting through combustion air streaming in from the underside (5) is formed on the top (2).
2. Grate bar according to claim 1, wherein a second wear plate (9) is arranged below the second curved section or the diagonal (8) transforming into the rear longitudinal surface (4) is positioned at a distance from the second curved section (8) lying above the same.
3. Grate bar according to claim 2, wherein the second wear plate (9) is arranged at a distance from the second curved section (8) lying above the same.
4. Grate bar according to claim 2 or 3, wherein the same has a central rib (11), which is connected with the top (2) and on which the first and second wear plates (7, 9) are fitted or formed.
5. Grate bar according to claim 4, wherein the same has support bridges (12), with which the central rib (11) is supported against the top (2).
6. Grate bar according to one of the claims 4 or 5, wherein the central rib (11) has at least one recess (13) into which a connection means, in particular a connection rod, can be inserted for connecting two grate bars arranged next to each other.
7. Grate bar according to one of the preceding claims, wherein the same has at least one support part (14) with which the grate bar (1) can be laid on a support rod (18).
8. Grate bar according to one of the preceding claims, wherein the same is made of one piece.
9. Grate bar according to one of the claims 1 to 7, wherein the first and second wear plates (7, 9) have a higher corrosion resistance against high temperature corrosion than the first or second curved section (6, 8) lying above the same.

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