EP3967927B1 - Water-cooled grate block for a combustion installation - Google Patents

Description

Combustion grates for the large-scale incineration of waste have been known to experts for a long time. Such combustion grates can be in the form of pusher combustion grates, which include moving parts to carry out stoking strokes. The fuel is conveyed in the transport direction from an inlet end of the combustion grate to an outlet end and is burned during this process. In order to supply the combustion grate with the oxygen required for combustion, appropriate air inlets are provided through the combustion grate, through which the air - also known as 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 stepped manner, whereby in the case of so-called pusher grates, the front end of a grate block, viewed in the push direction, rests on a support surface of the adjacent (underlying) grate block in the transport direction and is moved on this support surface with the corresponding push movement.

Due to the fuel being transported over the grate blocks, the former are generally exposed to relatively high levels of wear. In the front area of each grate block, the fuel is transported 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. The mechanical abrasion caused by the fuel is particularly high in this front end area of the support surface.

Due to the high temperatures during combustion and in the combustion chamber, the grate blocks are also exposed to very high thermal stress. During normal operation of the combustion grate, this thermal stress is particularly high in the area of the support surface, although the combustion material lying on the grate block has a certain insulating effect. Temperature peaks and the associated stress peaks occur particularly when the combustion material is unevenly distributed on the combustion grate and therefore only forms a thin insulating layer in some places, or when this insulating layer is missing entirely. The thermal stress promotes erosion through abrasion and chemical reactions taking place on the support surface, which further damage the support surface. All of this ultimately leads to a shortening of the service life of the grate block.

In order to reduce the thermal load, 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. Water or air is usually used as a coolant, which is why grate blocks are often referred to as air- or water-cooled. The type of cooling or cooling Coolant supply is the subject of a large number of patent applications and patents:
The EP 1 760 400 B1 reveals a water-cooled grate element made of cast steel with deflection elements that form meandering water channels. The disadvantage of such a water flow is that the cooling performance is impaired directly above the deflection elements, since the cooling liquid has no contact with the upper wall there and thus cannot transport away the heat generated by the combustion. Consequently, a combustion surface with so-called "heat hotspots" is created at these points.

The EN 10 2015 101 356 A1 and the EP 1 315 936 B1 reveal a grate bar with a cooling coil extending parallel to the combustion surface and 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 diverted outside the grate blocks by means of brackets.

EP 0 989 364 A1 discloses a generic grate block which comprises an internal cooling chamber. Water is fed into the cooling chamber via several inlet openings, which ensures good water mixing and an increased cooling effect. In one embodiment, the cooling fluid is fed into a cast-in pipe and fed through the grate block through various sections of the pipe.

When cooling using the 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.

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

This object is achieved according to the invention with a grate block according to claim 1 and a grate according to claim 14. 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 one above the other in a stepped manner and are designed in such a way that they shift and convey the fuel during combustion by means of pushing movements carried out 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, which runs at least partially parallel to a longitudinal axis L of the block body. The grate block according to the invention also comprises a flat cavity arranged directly below the support surface for receiving a cooling fluid. The flat cavity is formed on the upper side by the upper wall, bounded at the front by a front wall, underside by a floor, at the back by a rear wall and laterally by side walls, the floor being at least partially formed by a base plate. 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, as well as 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.

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

The term "pushing movements that can be carried out relative to one another" refers to pushing movements that can be carried out parallel to the longitudinal axis of the grate consisting of grate blocks. In the case of a stepped grate, the direction of movement is therefore parallel to the incline or gradient of the grate.

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 runs parallel to the direction of the waste to be treated. If the grate block is aligned so that the longitudinal axis and a width axis perpendicular 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, a "supporting surface" is understood to mean a surface that is arranged on the outer upper side, i.e. on the opposite side of the cavity, and on which the waste (combustible material) intended for thermal treatment rests. As mentioned at the beginning, this supporting surface is known to be exposed to increased thermal stress in incineration plants and is susceptible to erosion and caking of combustion products.

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.

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 the following, fluid supply line and fluid discharge line are understood to mean lines which are suitable for guiding cooling fluid into the cavity and for discharging it from it. The possibility of mentioned that the fluid stream can flow in both directions, i.e. it can be alternately supplied and discharged through both lines.

In the context of the present invention, the front side or front face is understood to mean the side in the region of the front wall.

In the sense of the present invention, a distribution element is defined as an obstacle which is designed in such a way that it enables a restriction and/or change in the direction of the flow and thus a distribution of the incoming cooling fluid. The distribution of the cooling fluid preferably takes place before or in the area where the cooling fluid enters the flat cavity. The distribution element can have various 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 cooling fluid flow flowing into the cavity can be distributed evenly across 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 has the advantage that the thermal load and wear of the grate blocks is reduced and also less burnt-out material is baked onto the grate blocks, which means that they have to be cleaned and maintained less often. This ultimately leads to less maintenance work having to be carried out, and thus the incineration plant can be operated more economically.

Preferably, the distribution element 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 across the width of the flat cavity (or a compartment of the flat cavity).

According to the invention, the flat cavity is connected to a front-side chamber. Said chamber preferably extends essentially parallel to - and preferably at least over half the length of - the front wall. In the sense of the invention, it is designed in such a way that the cooling fluid inflow into the flat cavity or the cooling fluid outflow from the flat cavity takes place through the chamber. Such an embodiment is shown in the attached Figure 2 shown.

According to the invention, the flat cavity and the chamber are connected to one another via several inflow openings. This enables pre-distribution of the cooling fluid before it hits the distribution element and thus also contributes to better distribution of the cooling fluid in the flat cavity.

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

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 towards 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-conductingly connected compartments.

Due to the partition wall, the fluid flow 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 guided through the passage, whereby it is diverted and flows back through a second compartment adjacent to the first compartment in the opposite direction, i.e. towards the front wall. Thanks to the partition wall, the rear areas of the cavity are also sufficiently supplied with fresh cooling fluid, so that the cooling performance is also guaranteed in these areas.

It was found that in known water-cooled grate blocks, air is transported into the cavity by the cooling fluid flow and can only get stuck there as air inclusions in corners or hard-to-reach places. Due to the lower density of air compared to water, any air inclusions tend to collect at the top of the cooling chamber and since the Since the thermal conductivity of air is significantly lower than that of water, such air inclusions lead to a 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 the compartments in order to remove any such air inclusions from the grate block. At the same time, the venting of the cavity or the compartments prevents air from being carried along with the cooling fluid over the entire length of the fluid flow.

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.

The ventilation opening preferably has a diameter of 2 - 12 mm, particularly preferably 4 - 5 mm. This size enables the grate block including the ventilation opening to be produced using the known casting processes.

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 in the cavity. In this embodiment, the partition wall 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 through the compartments and is not accelerated or slowed down due to a change in the cavity or compartment geometry. This prevents turbulences from occurring due to acceleration or deceleration of the fluid flow within the cavity or compartments.

Preferably, 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 face area, the largest possible space is freed up beneath the block body.

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 usual cooling fluid circulation volume, a flow rate is obtained at which the flow automatically vents the entire line system of the grate block including the cavity. Depending on the design, 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 limited 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 of 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 hits the distribution element, thereby calming turbulence. The water can preferably flow through openings in the distribution element (if present) or over or around them.

In a preferred embodiment of the grate block, the distribution element is designed in the form of a baffle plate or a baffle plate. Other preferred embodiments include a distribution element that is designed as a hump, cover, perforated plate or crossbar. 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- or ramp-shaped cross-section in the width direction, i.e. parallel to the front wall. The cooling fluid therefore flows over the distribution element perpendicular to the front wall and opposite to the direction of movement of the combustion material.

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.

In the case of a cross beam, it is understood here 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.

As mentioned above, the distribution element enables the cooling fluid flow to be evenly distributed over as much of the cavity as possible and, if the cavity has compartments, over the width of the compartments. This even 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 takes place 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 in or subsequently inserted 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 base and/or to the upper wall on 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.

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 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 has been found that turbulence in the cooling fluid occurs particularly frequently when it enters the cavity - i.e. in the mouth area of the inflow line. Since the thermal load in the front area of the grate block is particularly high, a reduced cooling capacity due to air inclusions has a doubly negative effect there. If the distribution element is arranged in the mouth area of the inflow line, a rapid calming down is achieved when the cooling fluid enters the cavity.

The distribution element preferably comprises a hump-, ramp- or hill-like obstacle which restricts or diverts 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 very particularly preferably 30 mm.

The combination of a hump-shaped 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 cooling fluid flow in the cavity. proven effective. Furthermore, the production of such a distribution element is easy to accomplish using the known casting processes and is therefore preferred.

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.

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

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.

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 makes it possible to convey additional air into the combustion chamber in order to ensure optimum combustion. Starting from the upper wall, the air supply opening can expand concentrically downwards (volcano-shaped), which prevents the air supply opening from becoming blocked 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 to 4 - 12 mm. In addition, they preferably expand in Direction of the base plate at an angle of 18 - 22° up to a smaller diameter of 22 - 28 mm.

The block body is preferably manufactured in one piece as a cast part and preferably also comprises a piece of the base. The base plate, which preferably forms the base at least partially, is preferably welded to the block body and thus delimits the cavity. This means that a part of the base is preferably 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 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 a manufacture of the block body is particularly inexpensive 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 the base plate is attached, for example by using a blasting agent.

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 support surface. This ensures that the largest possible area is available for heat exchange.

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.

The cooling fluid preferably has a temperature of 20 - 140 °C during operation of the grate block, i.e. during the combustion of high-calorie waste such as household waste or commercial waste, which means that operating temperatures of up to 250 °C can be achieved for the grate block. Furthermore, water from a closed circuit is used as the cooling fluid to prevent the entry of oxygen and thus the formation of corrosion. If water is used as the cooling fluid, it preferably contains no or only a small amount of lime.

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

Fig. 1

eine perspektivische Ansicht einer Ausführungsform eines erfindungsgemässen Rostblocks;

Fig. 2

eine perspektivische Ansicht einer Ausführungsform eines flächigen Hohlraums;

Fig. 3

eine perspektivische Ansicht einer Ausführungsform des Rostblocks aus Fig. 1 mit dem flächigen Hohlraum aus Fig. 2;

Fig. 4a

einen Längsschnitt entlang der Längsachse L durch eine Ausführungsform eines vorderen Bereichs des Blockkörpers aus Fig. 1;

Fig. 4b

einen Längsschnitt entlang der Längsachse L durch eine Ausführungsform eines vorderen Bereichs des Blockkörpers aus Fig. 1;

Fig. 5

einen Querschnitt entlang Breitenachse Q durch eine Ausführungsform eines vorderen Bereichs des Blockkörpers aus Fig. 1; und

Fig. 6

einen Längsschnitt entlang der Längsachse L durch eine Ausführungsform des Blockkörpers aus Fig. 1.

The invention is explained in more detail below using some embodiments shown in the figures. If alternative embodiments differ only in individual features, the same reference numerals have been used for the same features. They show purely schematically:

Fig.1

a perspective view of an embodiment of a grate block according to the invention;

Fig.2

a perspective view of an embodiment of a planar cavity;

Fig.3

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. 4b

a longitudinal section along the longitudinal axis L through an embodiment of a front region of the block body of Fig.1 ;

Fig.5

a cross section along 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 .

The Fig.1 The grate block 1 according to the invention shown 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 extends 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 nose), which connects the front region 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 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 with the aid 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 underneath (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 lie next to one another so that the side walls 6 of the grate block 1 border on the side walls of other grate blocks.

The block body 3 comprises air supply openings 21, 23 which are arranged in the front wall 15 and the upper wall 5 and through which the thermally treated waste can be supplied with air to promote combustion. Embodiments which do not have 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 passages which widen downwards so that parts of the waste to be treated do not get caught in the opening in the event of a possible passage.

The block body 3 further comprises a flat hollow space 50. As in Fig.2 As shown, the flat cavity 50 is delimited 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, 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 number 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.

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 limits 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 ) 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. Fig. 3 It is clearly visible that the air supply openings 23 pass from the upper wall through the flat cavity 50.

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 inflow opening 58 comprises a distribution element 74 in an opening area 72 facing the cavity 50, which is designed here as a hump or hill-like obstacle. The fluid flow, which is guided into the cavity 50 via the inflow opening 58, is distributed using the distribution element 74, so that no turbulence forms within the flat cavity 50, which would lead to the formation of foam or air bubbles and thus to a reduced cooling performance. The base 51 limits the cavity 50 at the bottom. The base plate 53 made of Fig.2 , which would be connected to the ground in the longitudinal direction L. The distribution element 74 could also be designed as a crossbar instead of the hump- or hill-like obstacle (not shown).

Figure 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). The cooling fluid flows after it has passed through the cavity has passed through the inflow 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 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 of low-alloy to high-alloy cast steel. In comparison to unalloyed cast steel, low-alloy to high-alloy cast steel also contains alloying elements such as chromium, nickel, molybdenum, vanadium, tungsten and others in varying proportions. The block body is preferably manufactured using 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.

Figure 6 shows a longitudinal section along the longitudinal axis L through the block body 3 of Fig.1 , whereby the distribution element in a front area 76 of the cavity 50 is not shown. The base 51 is designed as an integral part of the block body 3 and, together with the base plate 53, delimits the cavity 50 downwards. The cavity 50 is further delimited by the rear wall 68 and the front wall 15. The base plate 53 has analogous to the upper wall 5, the air supply openings 21. The air supply openings 21 expand concentrically from the upper wall 5 towards the base plate 53.

Claims (14)

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 flat cavity (50) is connected via a plurality of inflow openings (58) 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.
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. Grate block according to one of claims 1 or 2, 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.
4. Grate block according to claim 3, 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).
5. Grate block according to one of claims 3 or 4, characterised in that the partition wall (60) extends at least approximately parallel to one of the side walls (6).
6. Grate block according to one of claims 1 to 5, 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).
7. Grate block according to one of claims 1 to 6, 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) .
8. Grate block according to one of claims 1 to 7, characterised in that the distribution element (74) is located in a mouth region (72) of at least one of the inlet openings (58).
9. A grate block according to any one of claims 1 to 8, 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).
10. Grate block according to one of claims 1 to 9, 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
11. Grate block according to one of claims 1 to 10, characterised in that the upper wall (5) and/or the front wall (15) has at least one air supply opening (21, 23).
12. Grate block according to one of claims 1 to 11, 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).
13. Grate block according to one of claims 1 to 12, 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).
14. A grate comprising a plurality of grate blocks according to any one of claims 1 to 13.