EP4211397A1

EP4211397A1 - Water-cooled grate block for an incinerator

Info

Publication number: EP4211397A1
Application number: EP21777426.4A
Authority: EP
Inventors: Maurice Henri Waldner; Werner Brennwald
Original assignee: Hitachi Zosen Innova AG
Current assignee: Hitachi Zosen Innova AG
Priority date: 2020-09-09
Filing date: 2021-09-09
Publication date: 2023-07-19
Also published as: AU2021339933A1; CA3191998A1; JP2023540142A; EP3967927B1; US20230332769A1; EP3967927C0; EP3967927A1; MX2023002697A; WO2022053550A1

Abstract

The invention relates to a cooled grate block (1) as part of a grate for a system for thermally treating waste, comprising: a block body (3) in the form of a cast part having an outer supporting face (7) for the waste to be treated; a flat cavity (50) situated directly below the supporting face (7), for receiving a cooling fluid; a fluid feed line (52) and a fluid discharge line (54), which are connected to the cavity (50); at least one deflection element (66), which is arranged in the cavity (50) to direct a cooling fluid within the cavity (50) from the fluid feed line (52) to the fluid discharge line (54); and a valve element (74) situated in the end region (11) of the cavity (50), for distributing the cooling fluid fed into the cavity (50) through the fluid feed line (52).

Description

Water-cooled grate block for an incinerator

Combustion grates for the large-scale incineration of waste have been known to those skilled in the art for a long time. Such incineration grates can be in the form of thrust incineration grates, which include moving parts in order to carry out stoking. In this case, the material to be burned is conveyed in the transport direction from an inlet-side end of the combustion grate to an outlet-side end and is burned at the same time. In order to supply the incineration grate with the oxygen required for the incineration, appropriate air feeds are provided which pass through the incineration grate and via which the air—also called primary air—is introduced.

A frequently used combustion grate is the so-called stepped grate. This comprises grate blocks arranged next to one another, each of which forms a row of grate blocks. The rows of grate blocks are arranged one above the other in a stair-like manner, whereby in the case of so-called pusher grates the front end of a grate block, viewed in the direction of thrust, rests on a bearing surface of the grate block that is adjacent (below) in the direction of transport and is moved on this bearing surface with a corresponding thrust movement.

Due to the material to be burned being conveyed over the grate blocks, the former are generally exposed to a relatively high level of wear. In the front area of each grate block, the fuel is lifted from the support surface via a corresponding dropping edge (also called a nose) onto the support surface of the following or jettisoned beneath adjacent rust blocks. The mechanical abrasion caused by the material to be burned is particularly high in this front end area of the support surface.

Due to the high temperatures during combustion or In the combustion chamber, the grate blocks are also exposed to very high thermal loads. During normal operation of the combustion grate, this thermal load is particularly high in the area of the contact surface, although the combustion material lying on the grate block has an insulating effect to a certain degree. Temperature peaks and the associated load peaks occur in particular when the material to be burned is distributed unevenly on the combustion grate and as a result only forms a thin insulating layer in some places or when this insulating layer is completely absent. The thermal stress promotes abrasion erosion and chemical reactions occurring at the bearing surface which further damage the bearing surface. This all ultimately leads to a reduction in the life of the grate block.

In order to reduce the thermal load, the grate bars are normally treated with a coolant or Cooling fluid is cooled from below, ie on the side of the combustion grate opposite to the combustion. As a rule, water or air is used as a coolant, which is why the term air or water-cooled grate blocks is often used. The type of cooling the Coolant supply is the subject of a large number of patent applications or Patents :

EP 1 760 400 B1 discloses a water-cooled grate element made of cast steel with deflection elements which form meandering water ducts. The disadvantage of such a water flow is that the cooling capacity is impaired directly above the deflection elements, since the cooling liquid has no contact with the upper wall there and therefore cannot transport away the heat generated by the combustion. As a result, a burn surface with so-called “heat hotspots” develops at these points.

DE 10 2015 101 356 A1 and EP 1 315 936 B1 disclose a grate bar with a cooling coil which extends parallel to the combustion surface and to the front wall.

EP 0 811 803 B1 discloses cooled grate blocks in which the cooling lines run at right angles to the feed direction and are deflected outside the grate blocks by means of holders.

When cooling by means of the known cooling channels or cooling lines, the entire area of the combustion surface is by no means covered, which promotes the formation of the "heat hotspots" mentioned above.

In order to achieve the highest possible cooling performance, the focus is on maximizing the surface area available for heat exchange. With liquid coolants, the flow should be as even as possible of the coolant is of central importance. Otherwise, turbulence and bubble formation can occur in the cooling lines, which reduces the cooling capacity of the grate blocks.

It is therefore the object of the invention to eliminate the disadvantages of the prior art and to provide a grate block in which the cooled surface is proportionally maximized and at the same time the occurrence of turbulence in the coolant flow is reduced so that the cooling capacity can be further improved.

This object is achieved according to the invention with a grate block according to claim 1 and a grate according to claim 16 . Preferred embodiments of the invention are given in the dependent claims.

The invention relates to a cooled grate block as part of a grate for a plant for the thermal treatment of waste. In this grate, the grate blocks are usually arranged in a step-like manner one above the other and are designed in such a way that they shift and convey the material to be burned during combustion by means of thrust movements performed relative to one another. The grate block according to the invention comprises a block body designed as a cast part with an upper wall. The upper wall forms an outer support surface for the waste to be treated, running at least partially parallel to a longitudinal axis L of the block body. Furthermore, the grate block according to the invention comprises a flat cavity arranged directly below the bearing surface for receiving a cooling fluid. The planar cavity is thereby on the upper side by the upper wall, delimited on the front side by a front wall, on the underside by a floor, on the back by a rear wall and laterally by side walls, the floor being at least partially formed by a floor panel. The grate block according to the invention further comprises a fluid supply line and a fluid discharge line, both of which are connected to the cavity, and at least one deflection element arranged in the cavity in order to direct the cooling fluid in the cavity from the fluid supply line to the fluid discharge line. In a front area of the cavity of the grate block according to the invention there is also a distribution element for distributing the cooling fluid fed into the cavity through the fluid supply line.

The at least one deflection element is preferably located in the cavity in a rear area of the rear wall.

In the context of the present invention, grate blocks lying one on top of the other in a step-like manner are defined as grate blocks on a grate which are arranged like the steps of an ascending or descending staircase.

The term “thrust movements that can be carried out relative to one another” means thrust movements that can be carried out parallel to the longitudinal axis of the grate consisting of grate blocks. In the case of a stepped grating, the direction of movement runs parallel to the inclination or slope of the grate.

The "longitudinal axis of the grate block" refers to an axis which is parallel to the axis of the stepped The grate thus extends from the front wall to the rear wall of the grate block and thus runs parallel to the thrust direction of the waste to be treated. If the grate block is aligned in such a way that the longitudinal axis and a width axis running at right angles thereto are arranged in the horizontal plane, then the front wall is preferably arranged at least approximately in the vertical plane.

For the purposes of the present application, “support surface” means a surface that is arranged on the outer top side, ie on the opposite side of the cavity, and on which the waste intended for thermal treatment (combustion material) rests. As mentioned at the outset, this bearing surface in incineration plants is known to be exposed to increased thermal stress and is susceptible to erosion and caking of combustion products.

As a fluid flow Cooling fluid stream is in the sense of the present application, a stream of cooling fluid preferably water - defined, which of the

Fluid supply line to the fluid discharge line or vice versa is passed through the cavity.

In the context of the present invention, the term “flat cavity” is understood to mean that the cavity has a shape whose extent in the horizontal direction (length and width) is greater than in the vertical direction (height). The cavity preferably has a cuboid shape, at least in sections, with the largest surface parallel to the bearing surface. In particular, no pipelines are provided in the flat cavity, which transport the fluid from the fluid supply line to the fluid discharge line.

In the following, fluid supply line and fluid discharge line are understood to be lines which are suitable for conducting cooling fluid into the cavity and for discharging it from it. The possibility should be expressly mentioned here that the fluid stream can flow in both directions in each case, ie can be supplied and discharged alternately through both lines.

Within the meaning of the present invention, the front side or front side is understood to mean the side in the area of the front wall.

Within the meaning of the present invention, an obstacle is defined as a distribution element, which is designed in such a way that it allows a restriction and/or a change in direction of the flow and thus a distribution of the inflowing cooling fluid. The cooling fluid is preferably distributed before or in the area where the cooling fluid enters the planar cavity. The distribution element can have different shapes, as will be explained in more detail below.

The grate block according to the invention has the advantage over the prior art that the flow of cooling fluid flowing into the cavity can be distributed evenly over the width of the cavity thanks to the distribution element. This means that the formation of cooling fluid turbulence and foam formation can be reduced or even completely prevented, which leads to an increased cooling capacity of the grate block. The increased cooling capacity brings the The advantage is that the thermal stress and wear on the grate blocks is reduced and, moreover, fewer burned-out substances are baked onto the grate blocks, which means that they have to be cleaned and serviced less frequently. Ultimately, this means that less maintenance work has to be carried out, and the incinerator can therefore be operated more economically.

As described above, the flat cavity generally does not have any pipelines that could impair an even distribution of the cooling fluid in the cavity and thus reduce the cooling capacity.

The distribution element preferably extends at least in sections along a width axis which runs at least approximately parallel to the front wall. This enables a regular distribution of the cooling fluid over the width of the planar cavity (or a compartment of the planar cavity).

In a preferred embodiment of the grate block, the flat cavity is connected to a front chamber. Said chamber preferably extends essentially parallel to and preferably at least over half the length of the front wall. It is preferably designed in such a way that the cooling fluid flow into the flat cavity or the cooling fluid outflow from the planar cavity takes place through the chamber. Such an embodiment is shown in attached FIG.

The flat cavity and the chamber are preferably connected to one another via a plurality of inflow openings. this preferably enables a pre-distribution of the cooling fluid before it hits the distribution element and thus also contributes to a better distribution of the cooling fluid in the planar cavity.

The feeding of the cooling fluid through the chamber into the cavity also allows the front wall, which is also often referred to as the nose, to also be cooled. Although the front wall is usually exposed to a slightly lower thermal load than the bearing surface, cooling it helps to prevent fly ash or other combustion products from caking.

In a preferred embodiment of the grate block, the flat cavity has a dividing wall extending from the bottom to the top wall. This dividing wall preferably extends from the front wall in the direction of the rear wall of the cavity and preferably forms a passage in the area of the rear wall, so that the cavity is divided into two compartments that are connected in a fluid-conducting manner.

Because of the dividing wall, the fluid stream thus preferably flows through a first compartment of the cavity, which extends from the front wall along the longitudinal axis over a desired length of the cavity. In the area of the rear wall, the fluid flow is directed through the passage, as a result of which it is deflected and flows through a second compartment adjacent to the first compartment in the opposite direction, ie. H . towards the front wall, flows back. Thanks to the partition, the rear areas of the Cavity sufficiently supplied with fresh cooling fluid, so that the cooling capacity is guaranteed in these areas.

It has been found that in known water-cooled grate blocks, air is conveyed into the cavity by the flow of cooling fluid and can remain there as air pockets at best in corners or poorly accessible locations. Due to the lower density of air compared to water, any air pockets tend to accumulate at the top of the cooling chamber and since the thermal conductivity of air is significantly lower than that of water, such air pockets lead to a reduced cooling capacity of the grate block. In the case of a liquid cooling fluid, the grate block according to the invention therefore preferably comprises at least one vent opening for venting the cavity or of the compartments in order to transport such possible air inclusions out of the grate block. At the same time, the ventilation of the cavity or of the compartments prevents air from being entrained with the cooling fluid over the entire length of the fluid flow.

If the cavity is divided into compartments by a dividing wall, the ventilation opening is preferably formed in the dividing wall, preferably in the area of the front wall, in order to ventilate the cavity or to allow the compartments created by the partition.

The ventilation opening preferably has a diameter of 2-12 mm, particularly preferably 4-5 mm. This size allows the grate block incl. Vent opening can be generated with the known casting process.

In a preferred embodiment of the grate block, the dividing wall runs at least approximately parallel to one of the side walls and is preferably arranged centrally in the cavity. In this embodiment, the dividing wall thus divides the flat cavity into two compartments that are at least approximately the same size. This ensures that the fluid flow is evenly distributed through the cavity or flows through the compartments and not due to a change in the cavity or Compartment geometry is accelerated or slowed down. It is thus prevented that acceleration or deceleration of the fluid flow within the cavity or of the compartments turbulence arise.

The fluid supply line and the fluid discharge line are preferably connected to the flat cavity in the area of the front wall. By connecting the fluid supply line and the fluid discharge line with the cavity in the front or. As large a space as possible is free under the block body in the end-face area.

Both the fluid supply line and the fluid outflow line preferably have an inner diameter of 20-32 mm, preferably 22-30 mm and particularly preferably 26-28 mm. Line diameters of this size have the advantage that for the usual cooling fluid circulation quantity, a flow rate results at which the flow covers the entire line system of the grate block incl. Cavity automatically vented. Depending on the embodiment the distribution element can extend over the entire width of the cavity or only over parts of it.

In a preferred embodiment of the grate block, the distribution element is designed in such a way that it only allows a restricted flow of cooling fluid past the distribution element or over it, in order to enable an even distribution of the cooling fluid within the cavity. This even distribution of the cooling fluid flow enables increased cooling performance, since turbulence in the cooling fluid and foam formation are reduced or prevented.

In a specific preferred embodiment, the cooling fluid flowing in through the fluid supply line first strikes the distribution element, as a result of which turbulence is calmed. The water can preferably flow through openings in the distribution element (if present) or over or around it.

In a preferred embodiment of the grate block, the distribution element is designed in the form of an impact plate or an impact plate. Further preferred embodiments include a distribution element which is designed as a hump, screen, perforated plate or crossbeam. The longitudinal axis of the distribution element preferably runs approximately parallel to the front wall.

If the distribution element is designed as a hump, this means that the distribution element has a hill-shaped or hill-shaped cross section in the width direction, ie parallel to the front wall. The cooling fluid thus flows perpendicular to the front wall and opposite to the direction of movement of the combustion material over the distribution element.

In the case of a perforated plate, it is understood here that the distribution element consists of a plate which has a front surface facing the fluid flow with at least one opening through which the fluid flow is conducted.

In the case of a transverse beam, it is understood here that the distribution element forms a wall or a beam, over or under which the cooling fluid can flow. The bar preferably extends along the entire width of the grate block and at least approximately parallel to the front wall.

As mentioned above, the distribution element enables the cooling fluid flow to be distributed evenly over as far as possible the entire width of the cavity and, if the cavity has compartments, over the width of the compartments. This uniform distribution of the cooling fluid flow allows for increased cooling performance, since turbulence in the cooling fluid and foaming can be reduced or prevented. The distribution usually takes place in the area where the cooling fluid enters the cavity and can be achieved with the aid of a distribution element of simple design. The distribution element can preferably be cast at the same time or used later as a separate component.

Furthermore, the distribution element preferably extends in the width direction at least over the width of an opening cross section of the fluid supply line. In a preferred embodiment of the grate block, the distribution element is connected to the bottom and/or to the top wall. If the distribution element is designed as a crossbar, this preferably forms a slit-like fluid passage opening with the top wall and/or the bottom. The fluid passage opening is particularly preferably formed between an upper edge of the crossbar and the upper wall. The fluid passage opening preferably has a clear width of 1 to 15 mm, preferably 2 to 10 mm and particularly preferably 3 to 6 mm.

With regard to an even distribution of the cooling fluid flow entering the cavity, the above-described embodiment of the distribution element as a crossbar with the above properties has proven to be particularly effective.

In a further preferred embodiment of the grate block, the distribution element is located in the mouth area of the at least one inflow line. It was found that turbulence in the cooling fluid occurs particularly frequently when it enters the cavity—that is, in the mouth area of the inflow line. Since the thermal load in the front area of the grate block is particularly high, a reduction in cooling capacity due to air inclusions has a doubly negative effect there. With an arrangement of the distribution element in the mouth area of the inflow line, rapid settling is achieved when the cooling fluid enters the cavity. Preferably, the distribution element comprises a hump, ridge or hill-like obstacle which restricts or deflects the flow of the cooling fluid from the fluid supply line. The distribution element preferably has a height of 5-15 mm, particularly preferably 8-12 mm and very particularly preferably 10 mm and a width of preferably 20-40 mm, particularly preferably 25-35 mm and particularly preferably 30 mm.

The combination of hump-shaped or A ridge or hill-like distribution element, which is located in the mouth area of the inflow line, has proven to be highly effective in distributing the flow of cooling fluid in the cavity. Furthermore, the production of such a distribution element can be easily accomplished using the known casting methods and is therefore preferred.

If the distribution element is designed as a crossbar, the distribution element preferably has an area which is at least 50% of the vertical cross-sectional area of the cavity or of the respective compartment.

The crossbar preferably has a thickness of 2 mm to 10 mm and a length of 50 mm to 250 mm.

If the distribution element is designed as a crossbar, this preferably extends over at least 50%, preferably over at least 75% and particularly preferably over at least 90% of the width of the cavity or of the respective compartment. In a preferred embodiment of the grate block, the top wall and/or the front wall has at least one air supply opening. This air supply opening makes it possible to transport additional air into the combustion chamber in order to ensure optimal combustion. Starting from the top wall, the air inlet opening can expand concentrically (volcano-shaped) downwards, which prevents the air inlet opening from becoming clogged with thermally treated waste. Such volcano-shaped air supply openings are preferably located in the top wall. Furthermore, they preferably have an oval opening cross-section with a diameter of 33-45 mm by 4-12 mm. In addition, they preferably widen in the direction of the bottom plate at an angle of 18-22° to a smaller diameter of 22-28 mm.

The block body is preferably made in one piece as a cast part and preferably also includes a piece of the base. The base plate, which preferably at least partially forms the base, is preferably welded to the block body and thus delimits the cavity. This means that a part of the base is preferably designed as an integral part of the block body and the cavity is also at least partially delimited on the base side by the base plate. This enables the cavity to be manufactured easily, since the cast part can be cast in one step and the cavity can then be formed by attaching, preferably by welding, the base plate. Such production of the block body is particularly favorable and makes the block body particularly durable and low-maintenance. The person skilled in the art is of course aware that the cast part can be further processed before attaching the base plate, for example by using a blasting medium.

In a preferred embodiment of the grate block, the cavity extends over at least 2/3 of the length of the support surface. Furthermore, the cavity preferably extends over at least 3/4 of the width of the bearing surface. This ensures that the largest possible area is available for heat exchange.

The hollow space should preferably cover at least the support surface for the waste to be treated, so that no thermally stressed, uncooled surface of the block body arises.

The cooling fluid preferably has a temperature of 20-140° C. during operation of the grate block, ie during the incineration of high-calorific waste such as household waste or commercial waste, whereby operating temperatures for the grate block of up to 250° C. are achieved. Furthermore, the cooling fluid—preferably water—from a closed circuit is used in order to prevent the entry of oxygen and thus the formation of corrosion. If water is used as the cooling fluid, this preferably has none or only a small amount

Percentage of lime on .

The invention further relates to a grate comprising several of the grate blocks described above. The invention is explained in more detail below with reference to some exemplary embodiments illustrated in the figures. If alternative embodiments differ only in individual features, the same reference symbols were used for the features that remained the same. They each show, purely schematically:

Fig. 1 shows a perspective view of an embodiment of a grate block according to the invention;

Fig. 2 is a perspective view of a

embodiment of a flat cavity;

Fig. 3 is a perspective view of a

Embodiment of the grate block from FIG. 1 with the flat cavity from FIG. 2 ;

Fig. 4a shows a longitudinal section along the longitudinal axis L through an embodiment of a front area of the block body from FIG. 1 ;

Fig. 4b shows a longitudinal section along the longitudinal axis L through an embodiment of a front area of the block body from FIG. 1 ;

Fig. 5 shows a cross section along the width axis Q through an embodiment of a front region of the block body from FIG. 1 ; and Fig. 6 shows a longitudinal section along the longitudinal axis L through an embodiment of the block body from FIG. 1 .

The one in Fig. 1 illustrated grate block 1 according to the invention is used for the thermal treatment of waste as combustion material (not shown), which moves in a direction of movement B over the grate or. is promoted. The grate block 1 comprises a block body 3 with an upper wall 5 and side walls 6. The upper wall 5 comprises an outer support surface 7, which extends along a longitudinal axis L of the grate block 1 from a rear area 9 of the block body 3 in the direction of a front area 11 of the Block body 3 extends. Furthermore, the block body 3 comprises a rounded overhang 13 in the front area 11 (hereinafter referred to as a nose), which connects the front area 11 to a front wall 15 .

In a grate arrangement, not shown, in which several individual grate blocks 1 are arranged one above the other in a stair-like manner, a sliding surface 17 adjoining the front wall 15 rests on the bearing surface 7 of another grate block (not shown). Thermally treated waste is conveyed in the direction of movement B with the aid of pushing movements performed relative to one another. For this purpose, the sliding surfaces 17 slide on the bearing surfaces 7 of the grate blocks arranged underneath (not shown). The relative thrust movements are performed along the longitudinal axis L and driven by a drive device, not shown, which the Movement transmitted via a bracket 19 to the block body. In such a grate arrangement, several grate blocks can lie next to one another, so that the side walls 6 of the grate block 1 adjoin the side walls of other grate blocks.

The block body 3 includes air supply openings 21, 23 located in the front wall 15 and the top wall 5, through which the thermally treated waste can be supplied with air to promote incineration. Embodiments which have no air supply openings are also conceivable, but not shown here. The air supply openings 23 in the top wall 5 are preferably designed as downwardly widening passages, so that parts of the waste to be treated are not in the event of a possible passage

opening get stuck .

The block body 3 also includes a planar cavity 50 . As in Fig. 2, the planar cavity 50 opposite the top wall 5 of the block body 3 is delimited by a bottom 51 and a bottom plate 53 . The cavity 50 further comprises a fluid supply line 52 and a fluid discharge line 54 which are each connected to a chamber 56 . The chamber 56 extends essentially parallel to the front wall 15 (FIG. 1) and is connected to the flat cavity 50 via inflow openings 58 . The flat cavity 50 further comprises a partition wall 60 which extends from the front wall (reference numeral 15 in FIG. 1) towards a rear wall 68 (FIG. 3) and forms a passage 64 such that the cavity 50 is divided into two compartments 62 .

Fig. 3 shows a view from below of a section through the grate block 1 from FIG. 1 in connection with that shown in FIG. 2 described flat cavity 50 . The bottom plate 53 from FIG. 2 , delimiting cavity 50 , has been removed here . The flat cavity 50 includes deflection elements 66 which deflect the fluid flow from the fluid supply line 52 (FIG. 2) to the fluid outflow line 54 (FIG. 2). In Fig. 3 it is also clearly visible how the flat cavity 50 in the rear region 9 of the block body 3 is delimited by the side walls 6 and the rear wall 68 . Next is in Fig. 3 clearly shows that the air supply openings 23 pass through the planar cavity 50 from the upper wall.

Fig. 4a and 4b show a longitudinal section along the longitudinal axis L through the front area of the block body from FIG. 1 with the air supply openings 21 in the front wall 15 . It can also be seen that the dividing wall 60 , which divides the cavity 50 , has an opening 70 which serves to vent the compartments 62 created by the dividing wall 60 . The inflow opening 58 comprises a distribution element 74 in a mouth region 72 facing the cavity 50, which is designed here as a hump-like or hill-like obstacle. The fluid flow, which is conducted via the inflow opening 58 into the cavity 50, is distributed with the aid of the distribution element 74, so that no turbulence forms within the planar cavity 50, which could lead to the formation of foam or foam. air bubbles and thus to a would lead to reduced cooling capacity. The bottom 51 delimits the cavity 50 at the bottom. Not shown is the base plate 53 from FIG. 2, which would connect to the ground in the longitudinal direction L. The distribution element 74 could also be designed as a crossbeam (not shown) instead of the hump-like or hill-like obstacle.

Figure 5 shows a cross section through the front wall 15 with the in FIG. 2 shown chambers 56, in which the fluid supply line 52 or. the fluid drain line 54 open. The cooling fluid flows through the fluid supply line 52 into the chamber 56 and is distributed via the inflow openings 58 in the cavity (not shown). After passing through the cavity, the cooling fluid flows through the inflow openings 58 ′ into the chamber 56 ′ and exits the block body 3 through the fluid outflow line 54 . The fluid outflow line 54 can be connected to a further fluid supply line of a further block body (not shown).

The block bodies shown have a length in the longitudinal direction L of 400-800 mm, preferably 500-750 mm and particularly preferably 650-700 mm. The block bodies shown have a width in the width direction Q of 280-500 mm, preferably 320-460 mm and particularly preferably 380-420 mm. The block bodies shown have a height of 100-200 mm, preferably 130-180 mm and particularly preferably 150-160 mm. The block body is preferably made from low-alloy to high-alloy cast steel. Compared to unalloyed cast steel, low- to high-alloy cast steel also contains varying proportions of alloying elements such as chromium, nickel, molybdenum, vanadium, tungsten and others . The block body is preferably produced by means of a casting or injection molding process. The inflow openings preferably have a diameter of 12-28 mm and particularly preferably a diameter of 16-22 mm.

FIG. 6 shows a longitudinal section along the longitudinal axis L through the block body 3 from FIG. 1 , the distribution element not being shown in a front region 76 of the cavity 50 . The bottom 51 is designed as an integral part of the block body 3 and together with the bottom plate 53 delimits the cavity 50 at the bottom. The cavity 50 is further delimited by the rear wall 68 and the front wall 15 . The base plate 53 has the air supply openings 21 analogously to the upper wall 5 . The air supply openings 21 widen concentrically from the upper wall 5 to the base plate 53 .

Claims

- 24 - Claims

1. Cooled grate block (1) as part of a grate for a plant for the thermal treatment of waste, in which the grate blocks are arranged in a stepped manner one above the other and are designed in such a way that the combustible material is shifted and conveyed during combustion by means of thrust movements performed relative to one another, comprising a block body (3) designed as a cast part with an upper wall (5) which forms an outer bearing surface (7) for the waste to be treated, running at least partially parallel to a longitudinal axis (L) of the block body (1), one directly below the bearing surface (7) arranged flat cavity (50) for receiving a cooling fluid, which is on the top side through the top wall (5), on the front side through a front wall (15), on the underside through a floor (51), on the back side through a rear wall (68) and is laterally delimited by side walls (6), wherein the bottom (51) is formed at least partially by a bottom plate (53), a Flu id supply line (52) and a fluid outflow line (54), which are connected to the cavity (50), at least one deflection element (66) arranged in the cavity (50) to direct a cooling fluid in the cavity (50) from the fluid supply line (52) to

directing fluid drain line (54), and a distribution element (74) arranged in an end region (76) of the cavity (50) for distributing the fluid fed into the cavity (50) through the fluid supply line (52).

2. Grate block according to claim 1, characterized in that the distribution element (74) extends at least in sections along a width axis (Q) which runs at least approximately parallel to the front wall (15).

3. Grate block according to Claim 1, characterized in that the flat cavity (50) is connected to a front-side chamber (56) which extends essentially parallel to the front wall (15) and through which the cooling fluid inflow into the flat cavity (50 ) or the cooling fluid outflow from the cavity (50).

4. Grate block according to claim 3, characterized in that the flat cavity (50) and the chamber (56) are connected to one another via a plurality of inflow openings (58).

5. Grate block according to one of Claims 1 to 4, characterized in that the flat cavity (50) has a partition wall (60) which extends from the bottom (51) to the top wall (5) and which extends from the front wall (15) towards the rear wall (68) of

Cavity (50) extends, in the region of the rear wall (68) forms a passage (64) and divides the cavity (50) into two fluid-conducting compartments (62).

6. Grate block according to claim 5, characterized in that the partition (60) has an opening (70) in the region of the front wall for venting the cavity (50) or the compartments (62) created by the partition (60).

7. Grate block according to one of claims 5 or 6, characterized in that the partition (60) runs at least approximately parallel to one of the side walls (6).

8. Grate block according to one of Claims 1 to 6, characterized in that the fluid supply line (52) and the fluid discharge line (54) are connected to the planar cavity (50) in the region of the front wall (15).

9. Grate block according to one of Claims 1 to 8, characterized in that the distribution element (74) is preferably in the form of a hump, a screen, a perforated plate or a crossbar which is/are at least approximately parallel to the front wall (15). runs.

10. Grate block according to one of Claims 4 to 9, characterized in that the distribution element (74) is located in a mouth area (72) of at least one of the inflow openings (58).

11. Grate block according to one of claims 1 to 10, characterized in that the distribution element (74) comprises a ridge-like or hill-like projection, - 27 - which the flow of cooling fluid from the

Fluid supply line (52) restricts or deflects.

12. Grate block according to one of claims 1 to 11, characterized in that the distribution element (74) is designed such that it only allows a restricted flow of cooling fluid past the distribution element (74) in order to distribute the cooling fluid evenly within the cavity (50) to allow.

13. Grate block according to one of claims 1 to 12, characterized in that the top wall (5) and/or the front wall (15) has at least one air supply opening (21, 23).

14. Grate block according to one of claims 1 to 13, characterized in that the block body (3) is produced in one piece as a cast part and the bottom plate (53) for delimiting the cavity (50) is preferably welded to the block body (3).

15. Grate block according to one of claims 1 to 14, characterized in that the cavity (50) extends over at least 2/3 of the length and/or over at least 3/4 of the width of the bearing surface (7).

16. Grate comprising a plurality of grate blocks according to any one of claims 1 to 15.