EP1612483B1 - Grate bar, combustion grate using the same and corresponding waste material incineration plant - Google Patents

Abstract

The grate plate for a combustion grate has an upper side (10), lower side (12), two long sides, and two broad sides. Adjacent to one long side (14) the grate plate has at least one device for the connection of a support element (20), and constructed below the upper side and close to the second long side (16) is at least one flow passage (32) along which air is guided from a region below the grate plate up to an opening (32o) on the second long side's section (16u) adjacent to the lower side. Independent claims are also included for the following: (A) a combustion grate, and especially a thrust combustion grate, equipped with a number of the aforesaid combustion grates; and (B) a waste material combustion system with a combustion grate.

Description

The invention relates to a grate plate for a combustion grate, a grate formed from grate plates and a waste incineration plant with such a combustion grate.

The most important component of a waste incineration plant is the combustion grate, which is arranged horizontally or inclined and on which the firing material, for example refuse, is conveyed from a first end to a second end, usually Ausbrandrost. The required combustion air is forced through the combustion grate. For this purpose corresponding openings are provided in the grate. In this way, the kiln (the residue) is essentially "dried" in three process steps, then "burned" and finally converted to slag. These three process steps can be controlled individually if required.

There are several types of combustion grates, including but not limited to the so-called booster combustion grate. Such a grate has moving parts (grate plates) which are suitable for carrying out scrubbing, whereby the kiln (the residue) is conveyed on the combustion grate. In this case, the individual grate plates, staggered in relation to each other in the region of their side facing the combustion chamber, lie on top of one another. If, for example, every second grate plate is movably arranged, it is achieved by the movement of this grate plate that the residue, which rests on the grate plate following in the transport direction, is transported on to the next grate plate.

In a combustion plant of the type mentioned different types of residues can be burned. Typical residuals are household waste, commercial waste, wood sawdust, waste wood, waste wood, processed fractions of various waste materials (RDF = refuse derived fuel), biomass or the like, for example sewage sludge. The individual types of residue differ with regard to their calorific value. However, this also applies within the individual types of residues. For example, household waste may have a calorific value between 5 and 20 MJ / kg. Depending on this calorific value, the thermal and mechanical stress of the combustion grate or its grate plates changes.

To counteract this wear, it is sufficient for the combustion of residues with a calorific value up to about 10 MJ / kg, the grate plates
to cool with air. An air-cooled combustion grate describe the EP 0 391 146 A1 and DE 201 11 804 U1 ,

In the combustion of Brenngut with higher calorific value combustion grates are often preferred, the grate plates
be cooled with a liquid, especially water. However, the procedural effort in a water cooling is clear higher than with air cooling. For certain combustion processes, the more intensive water cooling leads to an undesirably intensive cooling of the grate plates.

The object of the invention is to show a possibility in which by means of air cooling also combustible material (residues) with higher calorific values than hitherto usual, in particular with heating values> 10 MJ / kg, can be burned.

To solve this problem, the invention proceeds from the following consideration: Each grate plate is exposed to a particularly intensive heat load, in particular to the hearth space, that is to say in particular on its upper side and its front end face. Primary air is against
the bottom of the grate plates out, so it cools from below, and is pressed through openings in the grate plates or between the grate plates, in the resting on the grate plates Brenngutschicht. The heat-loaded part of each grate plate is on the underside of a certain cooling volume to dissipate the heat generated. However, especially in the edge region, the cooling is insufficient. Such areas, such as the combustion chamber facing end face (longitudinal side) of a grate plate is characterized particularly corrosion and erosion.

At this point, the invention begins; in that at least one flow channel is formed in the area below the upper side and adjacent to the front-side longitudinal side of the grate plate, along which air is guided selectively from below towards the upper side or the adjacent front longitudinal side. At the same time, the area of the top of the grate plate adjacent to the flow channel is made thinner than the area behind it, so that the cooling becomes more intense.

In this way, a type of air nozzle is formed, wherein the air with a correspondingly high flow velocity cools the critical front (the combustion chamber facing) portion of the respective grate plate "from below".

At the same time, this at least one flow channel is designed such that it has an air outlet opening on the portion of the corresponding end face (end face) adjacent to the underside, so that the air flow is then selectively directed to the surface of the grate plate following in the direction of transport of the material to be burned, and this surface likewise cools. By this targeted air irradiation of the adjacent grate plate results in the further advantage that observed there in the prior art deposits can be largely avoided. Such deposits, also called Aufschweißungen arise in the case of combustion grates in the prior art, for example, by precipitation of metals from the kiln.

In the "back" part of the grate plate may remain in the previously known cooling.

Thereafter, the invention in its most general embodiment relates to a grate plate for a combustion grate according to claim 1.

According to one embodiment, the grate plate is formed below the top with a plurality of recesses extending from an area adjacent to the first longitudinal side to an area adjacent to the second longitudinal side and open to the bottom.

Through these recesses, the top (upper face of the grate plate) can form relatively thin, for example 10-15 mm.

The flow channel or the flow channels extend according to an embodiment perpendicular to the longitudinal side of the grate plate. In other words, the air flow along the flow channels extends in the direction of the front end surface of the grate plate.

As stated, this "front" section of the grate plates is particularly at risk. In that regard, the length of the flow channel can be normally limited to a length corresponding to 10-50% of the width of the grate plate, with a length between 10 and 30% usually sufficient. This is especially the section that is not swept over by a booster combustion grate.

Usually, a grate plate on the circumference no exact cuboid shape. In particular, the front end face (second longitudinal side) therefore does not run perpendicular to the top of the grate plate. Rather, the second longitudinal side can extend at an angle α <90 ° to the upper side and optionally additionally have at least one further bend.

With regard to the flow channel, this means that the flow channel is not rectilinear, but follows the shape of the grate plate in this area, that is, for example - describes - on average - a semicircle or has several bends. In this way, at the same time results in an extension of the flow channel. An intensification of the cooling is achieved when the flow channel is relatively close to the respective surface areas of the grate plate. In other words, an upper (outer) boundary wall of the flow channel is formed by an (inner) surface of the upper side and an (inner) surface of the second longitudinal side.

A lower (inner) boundary wall for the flow channel can be formed by a rib which extends between walls or webs which form, for example, lateral boundaries of said recesses.

Is the underside of the grate plate (also called rust level) designed so that the top of the grate plate when resting the grate plate on a horizontal surface from the first longitudinal side to the second longitudinal side (ie from back to front) rising (slope, for example: 3-10 ° ), this facilitates the support of adjacent grate plates and the transport of the fuel along the combustion grate.

For this purpose, the underside, the second longitudinal side (front end side) adjacent to be formed with a downwardly projecting shoulder, as shown in the following description of the figures. In this case, the corresponding grate plate with this paragraph is on the following in the direction of transport of the fuel grate plate (rust level).

In contrast, its front longitudinal side terminates preferably at a distance from the upper side of the following grate plate, and correspondingly, the outlet opening of the flow channel is also above the contact surface of the following grate plate. In this way, the targeted flow of the surface of the adjacent grate plate is additionally favored. This too is illustrated and explained in the following description of the figures.

Alternatively, it would be possible to arrange the outlet opening of the flow channel in the lower portion of the front longitudinal side, which would result in an air flow substantially parallel to the top of the following grate plate.

The additional cooling according to the invention makes it possible to make the sections of the grate plate adjacent to the flow channel thinner than the remaining sections of the grate plate. This not only saves material, but also increases the cooling effect.

This "thinner" section can refer not only to the front longitudinal side of the grate plate, but also to adjacent sections of the top of the grate plate.

Grate plates of the type mentioned, for example, have a width of 40-60 cm and a length of several meters. In that regard, it is known to form a grate plate of several, adjoining, interconnected sections, so-called grate bars. The individual sections may be castings, wherein the flow channel can be formed in situ. Each section is thus one piece. The sections (grate bars) can also be composed of sub-sections, especially if they are welded from sheets. A grate bar, for example, a width (in the longitudinal direction of the entire grate plate) of 5-25 cm, but also beyond.

The connection of adjacent grate bars by means of known connection technology, for example by screwing or in that a plurality of grate bars are connected to each other via connecting rods. Groups of grate bars formed in this way can in turn be connected to each other analogously.

In this case, an embodiment provides for the grate plates to be formed such that at least one recess is formed by two adjoining grate bars (sections), that is to say each grate bar forms a part, for example one half of the corresponding recess.

The invention further relates to a combustion grate, in particular a Schubverbrennungsrost, with a plurality of grate plates of the aforementioned type.

The term "shear combustion grate" includes all types of shear combustion grates, regardless of whether they are horizontal or inclined or the kiln is conveyed in one direction or the other. The term "shear combustion grate" is also not limiting insofar as shearbreasts are detected in which, for example, every other grate plate is movably arranged, but also such grates in which more than a stationary grate plate are placed between grate plates that perform Schürhübe.

Finally, the invention comprises a waste incineration plant, for example a waste incineration plant, with a combustion grate of the aforementioned type.

Other features of the invention will become apparent from the features of the claims and the other application documents. The disclosed features may be essential in any combination for the invention.

Figur 1:

Einen Vertikalschnitt durch den vorderen Abschnitt zweier aufeinander liegender Rostplatten eines Schubverbrennungsrostes

Figur 2:

Einen Schnitt entlang der Linie A-A gemäß Figur 1

The invention will be explained in more detail below with reference to an embodiment. Show - each in a highly schematic representation -

FIG. 1:

A vertical section through the front section of two superimposed grate plates of a shearburning grate

FIG. 2:

A section along the line AA according to FIG. 1

The basic structure of a grate plate is based on the lower grate plate in FIG. 1 explains: The grate plate has an upper side 10, a lower side 12, a rear longitudinal side 14, a front longitudinal side 16 and corresponding to two broad sides, which are not visible due to the sectional view. The upper end face 10o of the top 10 is flat. The front, second longitudinal side 16 is angled at an angle α (approximately 45 °) relative to the surface 10o and then has an angling 16w.

Adjacent to the first (rear) longitudinal side 14, the grate plate on the underside a in the longitudinal direction (in the drawing plane) extending recess 18 in which a round rod 20 is located, on which the grate plate is supported. With the help of this round rod 20 is in FIG. 1 above shown grate plate in the direction of arrow P movable.

In the region of the bottom 12, each grate plate is formed with a plurality of juxtaposed recesses 22. Each recess 22 is bounded laterally (parallel to the broad sides) of walls, in which case only one wall 24 can be seen. At the far end of the Grate plate, the recess 22 is bounded by a corresponding portion 14a of the first longitudinal side and at the front (in a combustion chamber 26 facing) portion of the front (second longitudinal side) 16. From the wall 24 protrude a plurality of cooling fins 28 in the recess 22nd

Between adjacent walls 24 also extends a wall 30, which has a substantially arcuate shape in the sectional view and at the front end, the second longitudinal side 16 adjacent, merges into a thickened portion 30v, which projects beyond a lower end edge 16u of the front, second longitudinal side 16 and forms a bearing surface 30u for the grate plates.

This wall 30 forms a lower (inner) boundary wall of a flow channel 32 which extends from the lower end 16u of the second longitudinal side 16 parallel to the wall 30 (thus forming the inner surface of the longitudinal side 16 the other boundary for the flow channel 32) and in its further course is delimited by a lower surface 10u of the upper surface 10 before opening towards the underside 12 of the grate plate. In the illustrated embodiment, the wall 30 ends at the lower end of the space 22; but he could also end earlier. In the illustrated embodiment, a funnel-like inflow opening for cooling air is provided, which is provided below the grate plate and the entire recess 22 flows against, including the area below the wall 30th

At the in FIG. 1 shown upper grate plate is the part of the cooling air, which is guided through the flow channel 32, symbolized by the arrow K. The cooling air thus occurs at the funnel-shaped end 32k the flow channel 32 and is then first along the inner surface 10u of the top 10 and then along the inner surface 16i of the longitudinal side 16 before the cooling air exits in the region of the opening 32o and impinges on the top 10 of the adjacent grate plate and these flows.

The supply of additional cooling air is in the lower part of FIG. 1 symbolized by arrows L.

By the flow of the top 10 of the grate plate with air of the flow channel 32 adjacent portion is thus additionally cooled from the outside. In this way, caking (so-called Aufschweißungen) by precipitation, especially metallic precipitates from the kiln, can be avoided in FIG. 1 are indicated by the dotted area 34.

Due to the more intensive cooling (additional cooling) in the front, particularly critical part of the grate plate, the wall thickness of the grate plate there thinner than in the rear part can be formed, as the figure shows.

By way of example, the thickness of the upper side 10 in the rear part 10r is 12 mm, in the front part (adjacent to the flow channel 32) only 6 or 8 mm. This applies analogously to the wall thickness of the second longitudinal side 16.

In the illustrated embodiment, the grate plate is formed by a plurality of juxtaposed sections that connect directly to each other and are interconnected. These cuts are also called grate bars.

FIG. 2 shows that each grate bar T1, T2 approximately centrally forms a wall 24, so that a recess 22 is formed in each case by two adjacent grate bars T1, T2 together. This also applies to the Flow channel 32, which here has an approximately oval cross-section.

In the FIG. 1 shown holes 36 serve to receive rods for connecting adjacent sections T1, T2. A plurality of such sections T1, T2, for example 50-60 sections, form a grate plate.

The grate plate shown is made as a cast iron, each grate bar T1, T2 is in one piece, that is, for example, the ribs 28 and the wall 30 are materially connected to the wall 24th

Claims (15)

1. Grate panel for a incineration grate with the following features:

   a) the grate panel has an upper side (10), a lower side (12), two longitudinal sides (14, 16) and two broad sides,

   b) adjacent to a first longitudinal side (14) the grate panel has at least one arrangement for the connection of a support element (20),

   c) formed below the upper side (10) and next to the second longitudinal side (16) is at least one flow channel (32), along which air can be conducted from an area beneath the grate panel to an opening (32o) in the section (16u) of the second longitudinal side (16) adjacent to the lower side (12),

   and characterized in that the upper side (10) of the grate panel is thinner in its section (10v) adjacent to the flow channel (32) than in the section (10r) lying behind the flow channel (32).
2. Grate panel according to claim 1, which is configured beneath the upper side (10) with a plurality of recesses (22), which each extend from an area (14a) adjacent to the first longitudinal side (14) to an area adjacent to the second longitudinal side (16) and are open towards the lower side (12).
3. Grate panel according to claim 1, the flow channel (32) of which extends perpendicular to longitudinal sides (14, 16) of the grate panel.
4. Grate panel according to claim 1, the flow channel (32) of which has a length that corresponds to 10 to 50% of the length of the broad sides.
5. Grate panel according to claim 1, the second longitudinal side (16) of which runs at an angle α <90° to the upper side (10).
6. Grate panel according to claim 1, the second longitudinal side (16) of which has at least one bend (16w).
7. Grate panel according to claim 1, in which an upper (outer) delimiting wall of the flow channel (32) is formed by the upper side (10) and the second longitudinal side (16).
8. Grate panel according to claim 1, in which a lower (inner) delimiting wall (30) of the flow channel (32) is formed by a rib, which extends between walls (24), which form lateral limits of the related recess (22).
9. Grate panel according to claim 1, the lower side (12) of which is configured such that the upper side (10) of the grate panel, when the grate panel is placed onto a horizontal surface, runs upwards from the first longitudinal side (14) to the second longitudinal side (16).
10. Grate panel according to claim 1, the lower side (12) of which, adjacent to the second longitudinal side (16), is formed with a step (30v) protruding downwards.
11. Grate panel according to claim 1, in which the second longitudinal side (16) is thinner in its section adjacent to the flow channel (32) than the upper side (10) in the section (10r) lying behind the flow channel (32).
12. Grate panel according to claim 1, consisting of several interconnected sections (T1, T2) adjoining each other in the direction of the longitudinal sides (14, 16).
13. Grate panel according to claim 12, in which at least one recess (22) is formed by two sections (T1, T2) adjoining each other.
14. Incineration grate, in particular a reciprocating incineration grate, with a plurality of grate panels according to one of claims 1 to 13.
15. Waste incineration plant with an incineration grate according to claim 14.

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