GRATE BAR

Abstract

A grate bar for combustion systems, having a substantially closed surface facing the combustion side, a rear support region designed to be placed on a grate carrier for forming the grate, and a front nose region, which is rounded between the surface and front edge and has a bearing surface designed on the lower face and further has cooling fins for air cooling which protrude from the lower face of the surface forming the grate. A head part in the interior has at least regionally thickened head fins for air cooling in the longitudinal direction and vertical direction below the surface facing the combustion side. The grate bar can also be a reversible grate bar.

Description

The present invention pertains to a grate bar according to the introductory clause of claim 1.

For the combustion of various fuels such as household trash, industrial waste, wood chips, solid or porous fuels, and fuels which are easy to ignite and those which are difficult, the conventional practice is to use incinerators with combustion chambers, in which the fuel is placed on, for example, a mechanically actuated grate, on which it is burned.

As a rule, the material processed in incinerators includes fuel with high heating value and fuel with low heating value, with the result that significant heat-related problems can occur in regard to the grate elements. Especially in the head area of the grate elements, the elements can burn or corrode because of the high thermal load.

A goal of the present invention is to provide a grate bar which comprises a long service life.

The goal of the invention is achieved by means of a grate bar according to the text of claim 1. Additional embodiments are described in the dependent claims.

What is proposed is a grate bar for incinerators with

• • an essentially closed surface on the combustion side;
  • a rear support area, designed to be placed on a grate carrier to form the grate;
  • a rounded nose at the front, between the surface and the leading edge, with a support surface on the bottom side; and
  • cooling ribs for air cooling, which project from the bottom side of the surface forming the grate,
    wherein the interior of the head comprises head ribs in the longitudinal and vertical directions, at least certain parts of which are made thicker than the other parts, for air cooling the combustion-side surface. As a result, the service life of the inventive grate bar is significantly prolonged, because, after exposure to heat has led to the erosion of the nose as a result of, for example, chlorine corrosion among other processes, and even though the head ribs may be blocked by combustion slag, the thickened parts of the head ribs form an additional barrier against the heat-caused loss of material and simultaneously allow the head part to be cooled by the head ribs.

In another embodiment, the head ribs comprise two or more, preferably two, three, or four, thickened parts arranged parallel to each other. In this way the service life of the grate bar can be extended even longer, because, after the loss of the outermost combustion surface, at least one more surface is available for heat-caused erosion.

In another inventive embodiment, the head ribs comprise essentially trapezoidal and/or funnel-shaped and/or polygonal and/or wedge-shaped thickened parts. It is conceivable that, if desired, the thickened parts of the head ribs could be exclusively polygonal or any desired combination of polygonal with other forms.

In another inventive embodiment, head slots are formed between a side wall and each of the head ribs. As a result of the design of the head part with head ribs and the head slots between them, the heat resulting from the combustion process can be dissipated across a large cooling surface. The head slots make it possible for the combustion air to circulate. The thermal wear occurs at first primarily on the head part of the grate bar. Once the combustion surface of the head part has been lost by heat-caused wear, the area behind it, in the form of the thickened trapezoidal parts of the head slots which have been blocked by combustion slag, are available for further wear. Thanks to the head slots, the combustion air can circulate and the head part can be cooled.

According to another embodiment, the head slots . . . a funnel, which is arranged inside the head part, the funnel leading to a tapered part of the head slot. The head ribs are arranged here between a lateral end wall and the extension-like head ribs, all of which together form a comb-like structure. According to yet another embodiment, approximately the forward third of the head ribs is thickened.

According to yet another embodiment, at least one part of the side wall comprises a recess extending along the head part.

According to yet another embodiment, the grate bar comprises a rear part, which is provided with a with at least one long slot, which is open to the surface in the rear area, and wherein the cooling ribs project into the interior of the rear part.

According to yet another embodiment, the grate bar is made of metal.

In an additional embodiment, the grate bar is designed as a reversible grate bar, with a rear nose designed in the same way as the front nose and head part. These types of reversible grate bars can be reversed when the first head part has reached the end of its life, and thus the other head part allows the grate bar to be used over an additional period of time equivalent in practice to the service life of the first head part. For this purpose, two support surfaces are formed on the bottom side, arranged symmetrically with respect to the center of the grate bar.

Another aspect of the invention pertains to a grate for use in the grate-firing chamber of an incinerator, wherein at least one transverse row of inventive grate bars is arranged in the grate in movable fashion, and wherein, following this first transverse row, a second transverse row with a grate bar an inventive grate bar is installed in stationary fashion. This achieves the goal that the material to be burned can be moved continuously toward the combustion side.

In another embodiment, the support surface of one grate bar overlaps the surface of the following grate bar in an offset, fish-scale like manner.

In another embodiment, several grate bars are arranged with their long sides parallel to each other.

Exemplary embodiments of the present invention are explained in greater detail below on the basis of the figures:

FIG. 1 shows a schematic cross-sectional side view of an inventive grate bar;

FIG. 2 shows a schematic view similar to that of FIG. 1;

FIG. 3 shows a first enlarged cross section along line E-E in FIG. 2;

FIG. 4 shows a second enlarged cross section along line B-B in FIG. 2;

FIG. 5 shows a third enlarged cross section along line A-A- in FIG. 2;

FIG. 6 shows an enlarged head part of an inventive grate bar similar to that of FIG. 7;

FIG. 7 shows a schematic plan view of an inventive grate bar;

FIG. 8a shows a schematic cross-sectional side view of an another head part of an inventive grate bar;

FIG. 8b shows a schematic plan view according to FIG. 8a;

FIG. 9a shows a schematic cross-sectional side view of yet another head part of an inventive grate bar;

FIG. 9b shows a schematic plan view according to FIG. 9a;

FIG. 10a shows a schematic cross-sectional side view of yet another head part of an inventive grate bar; and

FIG. 10b shows a schematic plan view according to FIG. 10a.

FIG. 1 shows a schematic cross-sectional side view C-C in FIG. 7 of an inventive grate bar 1 for an incinerator. These grate bars or elements can be arranged horizontally next to each other to any desired width. It is conceivable for the grate bars to be arranged in a first transverse row, with their long sides parallel to each other, after which at least one additional transverse row follows the first row. The first transverse row can comprise stationary grate bars, whereas the grate bars of the other transverse row are movable. Moving the grate bars makes it possible to transport the combustible material continuously toward the combustion side. It is conceivable that the transverse rows could alternate; that is, a stationary row could be followed by a movable row, which is followed in turn by a stationary row, etc. Other arrangements of stationary and movable transverse rows are also conceivable, however; for example, a movable transverse row could be followed by two stationary rows, followed in turn by a movable transverse row. One end 2 of the grate bar 1 is designed as a support area 2 with a nose-like shape, so that it can be attached to a bracket in an incinerator in the manner known in itself. The front end of the grate bar 1 comprises a rounded edge or nose 3 with a leading edge 3′ as an extension of the top combustion surface 4. A surface 4′ underneath the combustion surface 4 in the interior of the grate bar 1 can form another combustion surface after the combustion surface 4 has been lost by heat-caused corrosion. The support area 2 and the nose 3 are designed in such a way that the grate bars 1 can overlap each other in fish-scale fashion; that is, the support surface 5 located under the nose 3 is supported by or rests on the surface or top combustion surface 4 of the following grate bar 1, the set of such bars thus forming the grate surface of the incinerator. The grate bar also comprises a transverse rib 6 and a rear part 7. An area 8 between the leading edge 3′ of the nose 3 and the transverse rib 6 forms the head part 8.

FIG. 2 shows a schematic view according to FIG. 1. The reference numbers already introduced in FIG. 1 correspond to the features of FIG. 1. Also shown in FIG. 2 are a side wall 9 with recesses 10, 10′, 10″ and assembly openings 11 to allow the individual grate bars to be connected to each other.

FIG. 3 shows a first enlarged cross section, in this case along line E-E in FIG. 2. The combustion surface 4 at the top has a closed shape and merges with a lateral end wall 12. Head ribs 13, 13′ are formed in a first area A1 underneath the combustion surface 4 or, expressed differently, they are designed as extensions formed on the bottom side of the combustion surface and projecting into the interior of the grate bar 1. The head ribs 13 extend in the longitudinal direction of the grate bar 1 and also extend in the vertical direction. Head slots 14, 14′ are formed between the head ribs 13, 13′. The head slots 14, 14′ form grooves between the head ribs 13, 13′. The central head slot 14′ comprises a funnel 15′, which is somewhat wider than the funnels 15 of the head slots 14 adjacent to it on either side. The head slots 14, 14′ are open at the bottom. The head slots 14, 14′ are arranged between the lateral end wall 12 and the head ribs 13, 13′, designed as extensions of the head part 8, and form a comb-like structure in the interior of the head part 8. The funnels 15, 15′ lead to a tapered part 16, 16′ of the corresponding head slots 14, 14′.

FIG. 4 is a second enlarged cross section, this time along the line B-B in FIG. 2. In the rear part 7, cooling ribs 17 of different sizes project into the interior of the grate bar 1. Between the cooling ribs 17 are gaps 18. The side wall 9 with the corresponding recess 10″ is also shown.

FIG. 5 shows a third enlarged cross section, this time along the line A-A in FIG. 2. The side wall 9 is interrupted by the assembly opening 11. The cooling ribs 17 with the gaps 18 between them are also shown, the ribs proceeding from the combustion surface 4 and extending into the interior of the grate bar 1.

FIG. 6 shows the enlarged head part 8 of the inventive grate bar in a cross section through area Z in FIG. 7. A second area A2 of the combustion surface 4 is formed without head ribs 13, 13′ and without the intermediate head slots 14, 14′; that is, the second area A2 forms a solid one-piece sub-part of the head part 8. Following the second area A2 is a third area A3 with the trapezoidal head ribs 13, 13′ and the intermediate head slots 14, 14′. The head ribs 13, 13′ and head slots 14, 14′ extend toward the transverse rib 6 and proceed both in the longitudinal and in the vertical direction of the head part 8. The head slots 14, 14′, which extend to an external side of the head part 8, are formed between the lateral end walls 12 and the associated head ribs 13. Following the second area A2 there is in each case a funnel-shaped inlet 19, 19′ in the corresponding head slot 14, 14′. Each head slot 14, 14′ comprises the tapered part 16, 16′, which leads to a funnel-shaped outlet 20, 20′. The outlet 20, 20′ leads to a head slot part 21, 21′, which is wider than the tapered part 16, 16′. As a result, a part 22, 22′ of the head ribs 13, 13′ has a thickened, essentially trapezoidal region.

FIG. 7 shows a plan view of the inventive grate bar 1. The head part 8 with the head slots 14, 14′ and the head ribs 13, 13′ and the rear part 7 with the cooling ribs 17 and the intermediate gaps 18 are shown. The head slots 14, 14′ and the gaps 18 are arranged in series in the longitudinal direction of the grate bar 1 and are connected to each other. In the case of air-cooled grate bars, the temperature during the combustion process is the highest in the head part 8, and thus the heat-caused wear is also the greatest here. As a result of the large cooling surface provided by the comb-like structure of the head ribs 13, 13′ and as a result of the circulation of the combustion air through the head slots 14, 14′, the heat can be effectively dissipated. After the second area A2 (see FIG. 6) has been eroded by thermal wear, the following third area A3 (see FIG. 6) with the head ribs 14, 14′ is available for further thermal wear. The wear continues until the thickened trapezoidal parts 22, 22′ of the head ribs 14, 14′ have also been lost as a result of heat.

FIG. 8a shows a schematic cross-sectional side view of another head part 8′ of an inventive grate bar. Here a first layer 23 to be carried away by heat corrosion is shown, which is formed at least in part by the combustion surface 4. In addition, we also see in FIG. 8a a second layer 24 and a third layer 25. The second layer 24 and the third layer 25 are formed by the thickened head ribs 13, 13′. Between the first layer 23 and the second layer 24, there is a first recess 26. A second recess 27 lies between the second layer 24 and the third layer 25. The second layer 24 follows in the direction toward the interior of the additional head part 8′, coming after the first layer 23. The third layer 25 follows the second layer 24 in the direction toward the interior of the additional head part 8′. Following the third layer 25, the central head slot 14′ is shown. By means of these three layers 23, 24, 25, which are designed to be eroded by heat corrosion, it is possible for the inventive grate bar to have a longer service life, in that, as a result of the heat-caused loss of the first layer 23, there are still two more layers 24, 25 available for further loss, that is, for loss by thermal wear.

FIG. 8b shows a schematic plan view according to FIG. 8a. Here the three layers 23, 24, 25 are shown. The second and third layers 24, 25 comprise thickened polygonal parts 28, 28′, 29, 29′ on the head ribs 13, 13′. The thickened polygonal parts 28, 28′, 29, 29′ project from their corresponding head ribs 13, 13′ into the interior of the additional head part 8′. The first layer 23 is followed by the first recess 26; the first recess 26 is followed by the second layer 24. The second layer 24 is followed in turn by the second recess 27, which is followed by the third layer 25. The slot 14′ proceeds from the third layer 25. The central thickened parts 28′, 29′ are approximately twice as thick as the thickened parts 28, 29 extending on either side.

Between the thickened polygonal parts 28, 28′, 29, 29′ there lies in each case an associated head slot 14, 14′.

FIG. 9a shows a schematic cross-sectional side view of yet another head part 8″ of an inventive grate bar. Here the three layers 23, 24, 25 are shown along with the recesses 26, 27.

FIG. 9b shows a schematic plan view according to FIG. 9a. In contrast to FIG. 8a, the second layer 24 comprises thickened funnel-shaped areas 30, 30′, and the third layer 25 comprises thickened polygonal areas 31, 31′.

FIG. 10a shows a schematic cross-sectional side view of yet another head part 8″′ of an inventive grate bar. Three layers 23, 24, 25 are shown here. In addition, a fourth layer 32, which follows the third layer 25, extends toward the interior of the additional head part 8″′. Between the third layer 25 and the fourth layer 32 there is another recess 33.

FIG. 10b shows a schematic plan view according to FIG. 10a. In contrast to FIGS. 8a, and 9a, the second layer 24 comprises thickened wedge-shaped parts 34, 34′ and the third layer 25 comprises thickened polygonal areas 35, 35′. Following the third layer 25, the fourth layer 32 with thickened polygonal parts 36, 36′ is also shown. This gives the inventive grate bar an especially long service life.

It is conceivable that the thickened parts of the head ribs 13, 13′ described on the basis of the preceding figures could be combined with each other in any desired way.

Features with the same reference numbers in FIGS. 1-10b designate the same technical features in the various figures.

Claims

1-13. (canceled)

14. A grate bar for incinerators, comprising:

a substantially closed surface on a combustion side;

a rear support area configured to be placeable on a grate carrier to form the grate;

a front with a rounded nose between the closed surface and a leading edge, and with a bottom side having a support surface;

cooling ribs for air cooling arranged to project from a bottom side of the closed surface forming the grate; and

a head part that comprises head ribs for air cooling that extend in longitudinal and vertical directions of the grate bar underneath the combustion-side surface, at least certain parts of the head ribs being thicker than other parts of the head ribs.

15. The grate bar according to claim 14, wherein the head ribs comprise at least two thickened parts arranged parallel to each other.

16. The grate bar according to claim 14, wherein the head ribs comprise substantially trapezoidal and/or funnel-shaped and/or polygonal and/or wedge-shaped thickened parts

17. The grate bar according to claim 14, wherein head slots are formed between a side wall and each of the head ribs.

18. The grate bar according to claim 14, wherein the head slots form a funnel, which is arranged inside the head part, and the funnel leads to a tapered part of the head slot, and wherein the head slots are arranged between a lateral end wall and the extension-like head ribs, all of which together from a comb-like structure.

19. The grate bar according to claim 14, wherein a forward third of the head ribs is thickened.

20. The grate bar according to claim 17, wherein at least part of the side wall extending along the head part comprises a recess.

21. The grate bar according to claim 14, further comprising a rear part provided with at least one long slot open toward the closed surface, and wherein the cooling ribs project into an interior of the rear part.

22. The grate bar according to claim 14, wherein the grate bar is made of metal.

23. The grate bar according to claim 14, wherein the grate bar is a reversible grate bar, with a rear nose and head part configured the same as the front nose and head part.

24. A grate for use in a grate-firing chamber of an incinerator, comprising: a first transverse row; and a second transverse row following the first transverse row, each of said first and said second transverse rows having a grate bar according to claim 14, the grate bar in said first transverse row being arranged in the grate in movable fashion, and, the grate bar in said second transverse row being installed in stationary fashion.

25. The grate according to claim 24, wherein the support surface of the grate bar overlaps the surface of a following grate bar in an offset, fish scale-like fashion.

26. The grate according to claim 24, wherein several grate bars are arranged longitudinally parallel to each other in each row.