WATER-COOLED GRID BLOCK FOR A COMBUSTION PLANT

Description

[0001] Combustion grates for the large-scale incineration of waste have long been known to experts. Such combustion grates can be in the form of pusher combustion grates, for example, which include moving parts for stoking strokes. The fuel is conveyed in the transport direction from an inlet end of the combustion grate to an outlet end, where it is burned. To supply the combustion grate with the oxygen required for combustion, air inlets are provided through the combustion grate, through which the air—also called primary air—is introduced.

[0002] A frequently used combustion grate is the so-called stepped grate. This consists of adjacent grate blocks, each forming a row of grate blocks. The rows of grate blocks are arranged one above the other in a stepped manner. In so-called pusher grates, the front end of a grate block, viewed in the direction of travel, rests on a support surface of the adjacent (underlying) grate block in the direction of transport and is moved along this support surface with the corresponding pushing movement.

[0003] Due to the fuel being conveyed over the grate blocks, the former are generally subject to relatively high levels of wear. In the front area of ​​each grate block, the fuel is ejected from the support surface via a corresponding discharge edge (also called a nose) onto the support surface of the following or adjacent grate block below. Mechanical abrasion caused by the fuel is particularly high in this front end area of ​​the support surface.

[0004] Due to the high temperatures during combustion and in the combustion chamber, the grate blocks are also exposed to very strong thermal stress. During normal operation of the combustion grate, this thermal stress is particularly high in the area of ​​the support surface, even though the combustion material lying on the grate block has a certain insulating effect. Temperature peaks and the associated load peaks occur particularly when the combustion material is unevenly distributed on the combustion grate, resulting in only a thin insulating layer in some places, or when this insulating layer is completely missing. The thermal stress promotes erosion through abrasion and chemical reactions taking place on the support surface, which further damage the support surface. This ultimately leads to a shortened service life of the grate block.

[0005] To reduce thermal stress, the grate bars are normally cooled with a coolant or cooling fluid from below, i.e., on the side of the combustion grate opposite the combustion zone. Water or air are typically used as coolants, which is why grate blocks are often referred to as air- or water-cooled. The type of cooling or coolant supply is the subject of numerous patent applications and patents: EP 1 760 400 B1 discloses a water-cooled grate element made of cast steel with deflection elements that form meandering water guide channels. The disadvantage of this type of water flow is that the cooling performance directly above the deflection elements is impaired, as the coolant has no contact with the upper wall there and thus cannot dissipate the heat generated by combustion. Consequently, a combustion surface with so-called "heat hotspots" is created at these locations.

[0006] DE 10 2015 101 356 A1 and EP 1 315 936 B1 disclose a grate bar with a cooling coil extending parallel to the combustion surface and the front wall.

[0007] 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.

[0008] EP 0 989 364 A1 discloses a grate element for a plant for the thermal treatment of waste, comprising a plurality of grate blocks arranged one behind the other in a longitudinal direction, which are designed as fixed grate blocks and grate blocks movable in the longitudinal direction, wherein only the fixed grate blocks are designed for cooling with a fluid.

[0009] EP 1 191 282 A2 discloses the design of a block body in which the upper and front walls are thickened at their meeting point in such a way that a wall transition is created which fills the corner space between the two walls and whose inner surface delimits the cooling chamber in its uppermost region.

[0010] When cooling using the well-known cooling channels or cooling pipes, the entire area of ​​the combustion surface is not covered, which promotes the formation of the “heat hotspots” mentioned above.

[0011] To achieve the highest possible cooling performance, the focus is on maximizing the surface area available for heat exchange. With liquid coolants, the coolant flow is also crucial. Otherwise, turbulence and bubble formation can occur in the cooling lines, reducing the cooling performance of the grate blocks.

[0012] 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 area is proportionally maximized and at the same time the occurrence of turbulence in the coolant flow is reduced so that the cooling performance can be further improved.

[0013] This object is achieved according to the invention with a grate block according to claim 1 and a grate according to claim 15. Preferred embodiments of the invention are recited in the dependent claims.

[0014] 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 one above the other in a stepped manner and are designed such that they shift and convey the fuel during combustion by means of relative pushing movements. 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 support surface for receiving a cooling fluid.The flat cavity is bounded on the top side by the upper wall, on the front side by a front wall, on the bottom side by a floor, on the back side by a rear wall, and laterally by side walls, with the floor being at least partially formed by a base plate. Furthermore, the grate block according to the invention comprises a fluid supply line and a fluid discharge line, both of which are connected to the cavity, as well as at least one deflection element arranged in the cavity to direct the cooling fluid in the cavity from the fluid supply line to the fluid discharge line. A distribution element for distributing the cooling fluid fed into the cavity via the fluid supply line is also located in a front-side region of the cavity of the grate block according to the invention.

[0015] Preferably, the at least one deflection element is located in the cavity in a rear region of the rear wall.

[0016] For the purposes of the present invention, grate blocks arranged one above the other in a stepped manner are defined as grate blocks on a grate which are arranged like the steps of an ascending or descending staircase.

[0017] The term "relatively executable thrust movements" refers to thrust movements that can be executed parallel to the longitudinal axis of the grate, which consists of grate blocks. In a stepped grate, the direction of movement is thus parallel to the incline or gradient of the grate.

[0018] The "longitudinal axis of the grate block" refers to an axis that extends parallel to the axis of the stepped grate—i.e., from the front wall to the rear wall of the grate block—and thus parallel to the direction of flow of the waste to be treated. If the grate block is aligned so that the longitudinal axis and a width axis perpendicular to it are in the horizontal plane, the front wall is preferably arranged at least approximately in the vertical plane.

[0019] For the purposes of this application, a "supporting surface" is understood to mean a surface located on the outer upper side, i.e., on the opposite side of the cavity, on which the waste (combustible material) intended for thermal treatment rests. As mentioned at the beginning, this support surface is known to be exposed to increased thermal stress in incineration plants and is susceptible to erosion and caking of combustion products.

[0020] In the context of the present application, a fluid flow or cooling fluid flow is defined as a flow of cooling fluid - preferably water - which is conducted from the fluid supply line to the fluid discharge line or vice versa through the cavity.

[0021] The term "flat cavity" in the context of the present invention means that the cavity has a shape whose extent in the horizontal direction (length and width) is greater than in the vertical direction (height). Preferably, the cavity has a cuboid shape, at least in sections, with the largest area parallel to the support surface. In particular, no pipes are provided in the flat cavity to transport the fluid from the fluid supply line to the fluid discharge line.

[0022] In the following, fluid supply lines and fluid discharge lines are understood to be lines suitable for conveying cooling fluid into and out of the cavity. It should be expressly mentioned here that the fluid flow can flow in both directions, i.e., it can be supplied and discharged alternately through both lines.

[0023] In the context of the present invention, the front side or front face is understood to mean the side in the area of ​​the front wall.

[0024] For the purposes of the present invention, a distribution element is defined as an obstacle designed to restrict and / or change the direction of the flow and thus to distribute the incoming cooling fluid. The cooling fluid is preferably distributed before or in the area where the cooling fluid enters the flat cavity. The distribution element can have various shapes, as explained in more detail below.

[0025] The grate block according to the invention has the advantage over the prior art that the cooling fluid flow flowing into the cavity can be evenly distributed across the width of the cavity thanks to the distribution element. This reduces or even completely prevents the formation of cooling fluid turbulence and foam formation, leading to increased cooling performance of the grate block. The increased cooling performance has the advantage of reducing thermal stress and wear on the grate blocks. Furthermore, fewer burnouts are baked onto the grate blocks, requiring less frequent cleaning and maintenance. This ultimately leads to less maintenance work, making the incineration plant more economically viable.

[0026] As described above, the flat cavity usually does not have any pipes that could impair the even distribution of the cooling fluid in the cavity and thus reduce the cooling performance.

[0027] Preferably, the distribution element extends at least partially along a width axis that runs at least approximately parallel to the front wall. This enables a uniform distribution of the cooling fluid across the width of the planar cavity (or a compartment of the planar cavity).

[0028] In a preferred embodiment of the grate block, the flat cavity is connected to a front-side chamber. Said chamber preferably extends substantially parallel to—and preferably at least over half the length of—the front wall. It is preferably designed such that the cooling fluid inflow into the flat cavity and the cooling fluid outflow from the flat cavity occurs through the chamber. Such an embodiment is shown in the attached Figur 2 shown.

[0029] The flat cavity and the chamber are preferably connected to each other via several inlet openings. This preferably enables pre-distribution of the cooling fluid before it reaches the distribution element and thus also contributes to a better distribution of the cooling fluid in the flat cavity.

[0030] The flow of cooling fluid through the chamber into the cavity also allows the front wall, often referred to as the nose, to be cooled. Although the front wall is usually subject to somewhat lower thermal stress than the support surface, cooling it helps prevent the buildup of fly ash or other combustion products.

[0031] In a preferred embodiment of the grate block, the flat cavity has a partition wall extending from the bottom to the upper wall. This partition wall preferably extends from the front wall toward the rear wall of the cavity and preferably forms a passage in the region of the rear wall, so that the cavity is divided into two fluid-conducting compartments.

[0032] Due to the partition, the fluid flow preferentially 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 guided through the passage, where it is redirected and flows back through a second compartment adjacent to the first compartment in the opposite direction, i.e., toward the front wall. Thanks to the partition, the rear areas of the cavity are also sufficiently supplied with fresh cooling fluid, ensuring cooling performance in these areas as well.

[0033] It has been found that in known water-cooled grate blocks, air is transported into the cavity by the cooling fluid flow, where it can become trapped as air pockets in corners or hard-to-reach places. Due to the lower density of air compared to water, any air pockets tend to collect 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 reduced cooling performance 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 compartments in order to transport any such air pockets out of the grate block. At the same time, venting the cavity or compartments prevents air from being carried along with the cooling fluid along the entire length of the fluid flow.

[0034] If the cavity is divided into compartments by a partition wall, the vent opening is preferably formed in the partition wall, preferably in the region of the front wall, in order to enable ventilation of the cavity or the compartments created by the partition wall.

[0035] The vent opening preferably has a diameter of 2-12 mm, particularly preferably 4-5 mm. This size allows the grate block, including the vent opening, to be produced using conventional casting processes.

[0036] In a preferred embodiment of the grate block, the partition wall runs at least approximately parallel to one of the side walls and is preferably arranged centrally within the cavity. In this embodiment, the partition wall thus divides the flat cavity into two compartments of at least approximately equal size. This ensures that the fluid flow flows evenly through the cavity or compartments and is not accelerated or decelerated due to a change in the cavity or compartment geometry. This prevents turbulence from occurring within the cavity or compartments due to an acceleration or deceleration of the fluid flow.

[0037] According to the invention, the fluid supply line and the fluid discharge line are connected to the flat cavity in the area of ​​the front wall. By connecting the fluid supply line and the fluid discharge line to the cavity in the front or end area, the largest possible space is freed up below the block body.

[0038] Preferably, both the fluid supply line and the fluid discharge line 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 typical cooling fluid circulation rate, a flow velocity is achieved at which the flow automatically vents the entire piping system of the grate block, including the cavity. Depending on the design, the distribution element can extend across the entire width of the cavity or just over parts of it.

[0039] In a preferred embodiment of the grate block, the distribution element is designed to allow only a limited flow of cooling fluid past or over the distribution element, enabling a uniform distribution of the cooling fluid within the cavity. This uniform distribution of the cooling fluid flow enables increased cooling performance, as turbulence of the cooling fluid and foam formation are reduced or prevented.

[0040] In a specific preferred embodiment, the cooling fluid flowing through the fluid supply line first encounters the distribution element, thereby calming turbulence. The water can preferably flow through openings in the distribution element (if present), over them, or around them.

[0041] In a preferred embodiment of the grate block, the distribution element is designed in the form of a baffle plate or a baffle plate. Further preferred embodiments include a distribution element designed as a hump, a baffle, a perforated plate, or a crossbar. The longitudinal axis of the distribution element preferably runs approximately parallel to the front wall.

[0042] If the distribution element is designed as a hump, this means that the distribution element has a hill- or embankment-shaped cross-section in the width direction, i.e., parallel to the front wall. The cooling fluid thus flows over the distribution element perpendicular to the front wall and opposite to the direction of movement of the combustion material.

[0043] 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 passed.

[0044] In the case of a crossbar, this means that the distribution element forms a wall or a beam over or under which the cooling fluid can flow. Preferably, the beam extends along the entire width of the grate block and at least approximately parallel to the front wall.

[0045] As mentioned above, the distribution element enables a uniform distribution of the cooling fluid flow across, if possible, the entire width of the cavity and, in the case of compartments, across the width of the compartments. This uniform distribution of the cooling fluid flow allows for increased cooling performance, as turbulence of the cooling fluid and foam formation can be reduced or prevented. Distribution usually occurs in the area where the cooling fluid enters the cavity and can be achieved using a simply designed distribution element. The distribution element can preferably be cast into the cavity or retrofitted as a separate component.

[0046] 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.

[0047] In a preferred embodiment of the grate block, the distribution element is connected to the base and / or to the upper wall at the top. If the distribution element is designed as a crossbeam, it preferably forms a slot-like fluid passage opening with the upper wall and / or the base. The fluid passage opening is particularly preferably formed between an upper edge of the crossbeam 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.

[0048] With regard to a uniform distribution of the cooling fluid flow entering the cavity, the above-described embodiment of the distribution element as a crossbar with the above-mentioned properties has proven to be particularly effective.

[0049] In a further preferred embodiment of the grate block, the distribution element is located in the opening area of ​​at least one inlet line. It has been found that turbulence in the cooling fluid occurs particularly frequently at the entry into the cavity—that is, at the opening area of ​​the inlet line. Since the thermal load is particularly high in the front area of ​​the grate block, a reduction in cooling performance due to air inclusions has a doubly negative effect. By arranging the distribution element in the opening area of ​​the inlet line, rapid settling is achieved when the cooling fluid enters the cavity.

[0050] The distribution element preferably comprises a hump-, embankment-, or hill-like obstacle that 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 most preferably 10 mm, and a width of preferably 20-40 mm, particularly preferably 25-35 mm, and most preferably 30 mm.

[0051] The combination of a hump-shaped, ridge-shaped, or hill-like distribution element located at the inlet of the inlet line has proven highly effective in distributing the cooling fluid flow within the cavity. Furthermore, the production of such a distribution element is easy to accomplish using conventional casting processes and is therefore preferred.

[0052] In the event that 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 the respective compartment.

[0053] The crossbeam preferably has a thickness of 2 mm to 10 mm and a length of 50 mm to 250 mm.

[0054] In the event that 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 the respective compartment.

[0055] In a preferred embodiment of the grate block, the upper wall and / or the front wall has at least one air supply opening. This air supply opening allows additional air to be supplied to the combustion chamber to ensure optimal combustion. Starting from the upper wall, the air supply opening can widen concentrically downwards (volcano-shaped), thereby preventing clogging of the air supply opening with thermally treated waste. Such volcano-shaped air supply openings are preferably arranged in the upper 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 towards the base plate at an angle of 18-22° to a smaller diameter of 22-28 mm.

[0056] The block body is preferably manufactured as a single piece as a cast part and preferably also includes a piece of the base. The base plate, which preferably forms at least partially the base, is preferably welded to the block body and thus delimits the cavity. This means that preferably a part of the base is formed as an integral component of the block body, and the cavity is further delimited at least partially on the base side by the base plate. This enables simple production of the cavity, since the casting can be cast in a single step and the cavity can subsequently be formed by attaching, preferably by welding, the base plate. This type of production of the block body is particularly cost-effective and makes the block body particularly durable and low-maintenance.The expert is of course aware that the casting can be further processed before the base plate is attached, for example by using a blasting agent.

[0057] In a preferred embodiment of the grate block, the cavity extends over at least two-thirds of the length of the support surface. Furthermore, the cavity preferably extends over at least three-quarters of the width of the support surface. This ensures that the largest possible surface area is available for heat exchange.

[0058] The cavity 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 is created.

[0059] During grate block operation, i.e., during the combustion of high-calorie waste such as domestic or commercial waste, the cooling fluid preferably has a temperature of 20–140°C, which allows operating temperatures of up to 250°C for the grate block to be reached. Furthermore, the cooling fluid – preferably water – is used from a closed circuit to prevent the ingress of oxygen and thus the formation of corrosion. When water is used as the cooling fluid, it preferably contains no or only a small amount of lime.

[0060] The invention further relates to a grate comprising several of the grate blocks described above.

[0061] The invention is explained in more detail below with reference to some exemplary embodiments illustrated in the figures. Where alternative embodiments differ only in individual features, the same reference numerals have been used for the same features. They show purely schematically: Fig. 1 is a perspective view of an embodiment of a grate block according to the invention; Fig. 2 is a perspective view of an embodiment of a flat cavity; Fig. 3 is a perspective view of an embodiment of the grate block from Fig. 1 with the flat cavity made of Fig. 2 ; Fig. 4a a longitudinal section along the longitudinal axis L through an embodiment of a front region of the block body of Fig. 1 ; Fig. 4 shows a longitudinal section along the longitudinal axis L through an embodiment of a front region of the block body made of Fig. 1 ; Fig. 5 a cross section along the width axis Q through an embodiment of a front region of the block body of Fig. 1 ; and Fig. 6 a longitudinal section along the longitudinal axis L through an embodiment of the block body of Fig. 1 .

[0062] The Fig. 1 The illustrated grate block 1 according to the invention is used for the thermal treatment of waste as combustion material (not shown), which is moved or conveyed over the grate in a direction of movement B. 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 region 9 of the block body 3 in the direction of a front region 11 of the block body 3. Furthermore, the block body 3 comprises in the front region 11 a rounded overhang 13 (hereinafter referred to as a nose), which connects the front region 11 to a front wall 15.

[0063] In a grate arrangement (not shown), in which several individual grate blocks 1 are arranged one above the other in a stepped manner, a sliding surface 17 adjacent to the front wall 15 rests on the support surface 7 of another grate block (not shown). Thermally treated waste is conveyed in the direction of movement B by means of pushing movements carried out relative to one another. For this purpose, the sliding surfaces 17 slide on the support surfaces 7 of the grate blocks arranged below (not shown). The relative pushing movements are carried out along the longitudinal axis L and driven by a drive device (not shown), which transmits the movement to the block body via a holder 19. In such a grate arrangement, several grate blocks can be located next to one another so that the side walls 6 of the grate block 1 border the side walls of other grate blocks.

[0064] The block body 3 comprises air supply openings 21, 23 arranged in the front wall 15 and the upper wall 5, through which the thermally treated waste can be supplied with air to promote combustion. Embodiments without air supply openings are also conceivable, but are not shown here. The air supply openings 23 in the upper wall 5 are preferably designed as downwardly widening passages, so that parts of the waste to be treated do not get stuck in the opening if they pass through.

[0065] The block body 3 further comprises a flat hollow space 50. As in Fig. 2 As shown, the flat cavity 50 is defined opposite the upper wall 5 of the block body 3 by a base 51 and a base plate 53. The cavity 50 further comprises a fluid supply line 52 and a fluid discharge line 54, each of which is connected to a chamber 56. The chamber 56 extends substantially parallel to the front wall 15 ( Fig. 1 ) and is connected to the flat cavity 50 via inlet 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 so that the cavity 50 is divided into two compartments 62.

[0066] Fig. 3 shows a view from below of a section through the grate block 1 from Fig. 1 in connection with the Fig. 2 described flat cavity 50. The base plate 53 made of Fig. 2 , which delimits the cavity 50, has been removed here. The flat cavity 50 comprises deflection elements 66, which direct the fluid flow from the fluid supply line 52 ( Fig. 2 ) to the fluid drain line 54 ( Fig. 2 ) redirect. In Fig. 3 It is also clearly visible how the flat cavity 50 in the rear area 9 of the block body 3 is delimited by the side walls 6 and the rear wall 68. Furthermore, Fig. 3 clearly visible that the air supply openings 23 pass from the upper wall through the flat cavity 50.

[0067] 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 partition wall 60, which divides the cavity 50, has an opening 70, which serves to ventilate the compartments 62 created by the partition wall 60. The inlet opening 58 comprises, in an opening region 72 facing the cavity 50, a distribution element 74, which is designed here as a hump-like or hill-like obstacle. The fluid flow, which is guided into the cavity 50 via the inlet opening 58, is distributed by means of the distribution element 74, so that no turbulences form within the flat cavity 50, which would lead to foam formation or air bubbles and thus to a reduced cooling performance. The base 51 delimits the cavity 50 at the bottom. Not shown is the base plate 53 made of Fig. 2 , which would connect to the ground in the longitudinal direction L. The distribution element 74 could also be designed as a crossbeam instead of the hump- or hill-like obstacle (not shown).

[0068] Figur 5 shows a cross section through the front wall 15 with the Fig. 2 shown chambers 56, into which the fluid supply line 52 and the fluid discharge line 54 open. The cooling fluid flows through the fluid supply line 52 into the chamber 56 and is distributed via the inlet openings 58 in the cavity (not shown). After passing through the cavity, the cooling fluid flows through the inlet openings 58' into the chamber 56' and exits the block body 3 through the fluid discharge line 54. The fluid discharge line 54 can be connected to a further fluid supply line of another block body (not shown).

[0069] 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 of low-alloy to high-alloy cast steel. Compared to unalloyed cast steel, low- to high-alloy cast steel additionally contains alloying elements such as chromium, nickel, molybdenum, vanadium, tungsten and others in varying proportions. The block body is preferably produced by casting or injection molding. The inflow openings preferably have a diameter of 12 - 28 mm and particularly preferably a diameter of 16 - 22 mm.

[0070] Figur 6 shows a longitudinal section along the longitudinal axis L through the block body 3 from Fig. 1 , wherein the distribution element in a front region 76 of the cavity 50 is not shown. The base 51 is formed as an integral part of the block body 3 and, together with the base plate 53, delimits the cavity 50 downwards. Furthermore, the cavity 50 is delimited by the rear wall 68 and the front wall 15. The base plate 53 has the air supply openings 21, analogous to the upper wall 5. The air supply openings 21 widen from the upper wall 5 concentrically toward the base plate 53.

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 one above the other in a staircase-like manner and are designed in such a way as to shift and convey the combustible material during incineration by means of pushing movements carried out relative to one another, comprising a block body (3) in the form of a casting with an upper wall (5) which forms an outer support surface (7) for the waste to be treated which extends at least partially parallel to a longitudinal axis (L) of the block body (1), a flat cavity (50) arranged directly below the bearing surface (7) for receiving a cooling fluid, which is bounded at the top by the upper wall (5), at the front by a front wall (15), at the bottom by a base (51), at the rear by a rear wall (68) and laterally by side walls (6), wherein the base (51) is formed at least partially by a base plate (53), a fluid supply line (52) and a fluid drain line (54), which are connected to the cavity (50), at least one deflection element (66) arranged in the cavity (50) for directing a cooling fluid in the cavity (50) from the fluid supply line (52) to the fluid discharge 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), characterised in that the fluid supply line (52) and the fluid discharge line (54) are connected to the flat cavity (50) in the region of the front wall (15).

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

3. Grating block according to claim 1, characterised in that the flat cavity (50) is connected to an end chamber (56) which extends substantially 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) takes place.

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

5. Grate block according to one of claims 1 to 4, characterised in that the flat cavity (50) has a partition wall (60) extending from the base (51) to the upper wall (5), which extends from the front wall (15) in the direction of the rear wall (68) of the cavity (50), forms a passage (64) in the region of the rear wall (68) and divides the cavity (50) into two compartments (62) connected in a fluid-conducting manner.

6. Grate block according to claim 5, characterised in that the partition wall (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 wall (60).

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

8. Grate block according to one of claims 1 to 7, characterised in that the distribution element (74) is preferably in the form of a hump, a panel, a perforated plate or a transverse bar, which runs at least approximately parallel to the front wall (15) .

9. Grate block according to one of claims 1 to 8, characterised in that the distribution element (74) is located in a mouth region (72) of at least one of the inlet openings (58).

10. A grate block according to any one of claims 1 to 9, characterised in that the distribution element (74) comprises a hill or hill-like projection which restricts or deflects the flow of cooling fluid from the fluid supply line (52).

11. Grate block according to one of claims 1 to 10, characterised in that the distribution element (74) is designed in such a way that it only allows a restricted flow of cooling fluid past the distribution element (74) in order to enable uniform distribution of the cooling fluid within the cavity (50).

12. Grate block according to one of claims 1 to 11, characterised in that the upper wall (5) and / or the front wall (15) has at least one air supply opening (21, 23).

13. Grate block according to one of claims 1 to 12, characterised in that the block body (3) is produced in one piece as a casting and the base plate (53) is preferably welded to the block body (3) to delimit the cavity (50).

14. Grate block according to one of claims 1 to 13, characterised 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).

15. A grate comprising a plurality of grate blocks according to any one of claims 1 to 14.