Rust rod with coolant channel

Abstract

Grate bar (20, 30) for a combustion furnace with - a surface (O) which, during operation, faces a combustion chamber (62), - a rear support area (T) designed to rest on a grid support (54) and - a front area (F) comprising a grate bar front (V) and a support area (AB) formed on an underside of the grate bar (20, 30), as well as - a coolant channel (L) integrated in the grate bar (20, 30) with a cooling coil (L) extending from a first coolant connection (KA1) to a second coolant connection (KA2), wherein the cooling coil (L) extends in the front region (F), preferably in a substantially U-shaped, stepped, nested arrangement, wherein the coolant channel (L) has several longitudinal cooling coil sections (L1, L2, L3, L4, L5, L6) which extend parallel to each other in a longitudinal direction (R) extending from the rear support region (T) to the front region (F), wherein the longitudinal cooling coil sections (L1, L2, L3, L4, L5, L6) each connect in the front region (F) of the grate bar (20, 30) via a head cooling coil section (K1, K2, K3) extending transversely to the longitudinal direction (R) to another longitudinal cooling coil section (L1, L2, L3, L4, L5, L6) are connected - wherein the cooling coil (L) has a first longitudinal cooling coil section (L1) which runs from the first coolant connection (KA1) in the rear support area (T) in a central area with respect to the width of the grate bar (20, 30) to the front area (F) and in the front area (F) is connected via a first head cooling coil section (K1) to a second longitudinal cooling coil section (L2) which runs in the opposite direction antiparallel and adjacent to the first longitudinal cooling coil section (L1) from the front area (F) back to the support area (T), and - wherein the second longitudinal cooling coil section (L2) in the support area (T) is connected to a third longitudinal cooling coil section (L3) which runs in the opposite direction and antiparallel to the second longitudinal cooling coil section (L2) on a first longitudinally extending outer side (R) of the grate bar (20, 30), wherein a sixth longitudinal cooling coil section (L6) is located between the second longitudinal cooling coil section (L2) and the third longitudinal cooling coil section (L3), and - wherein the third longitudinal cooling coil section (L3) is connected via a second head cooling coil section (K2) forming an outer reversing stage to a fourth longitudinal cooling coil section (L4), which runs from the front area (F) on one of the first longitudinal outer sides of the grate bar (20, 30) opposite the second longitudinal outer side to the support area (T), - wherein the fourth longitudinal cooling coil section (L4) in the support area (T) is connected to a fifth longitudinal cooling coil section (L5) which runs in the opposite direction antiparallel and adjacent to the fourth longitudinal cooling coil section (L4) from the support area (T) to the front area (F), and - wherein the fifth longitudinal cooling coil section (L5) is connected via a third head cooling coil section (K3) forming a middle reversal stage to a sixth longitudinal cooling coil section (L6) which runs from the front area (F) to the second coolant connection (KA2) in the support area (T).

Description

[0001] In incineration plants for the disposal and energy recovery of residual materials, such as household waste, industrial waste, wood waste, and solid, porous, or liquid combustible materials with widely varying ignition qualities, the materials to be incinerated are first transported via conveyor belts (from a mixing plant) or cranes (from a bunker) into a feed hopper. The feed system, consisting of a sluice gate and a feed table, meteres the residual material into a combustion chamber. In the combustion chamber, the residual materials fall onto a grate, which conveys the material further during the combustion phases.

[0002] The aforementioned grate typically comprises a large number of grate bars arranged overlapping like roof tiles, ensuring the further transport of the residues to be burned.

[0003] In the first phase, the residues are dried in a drying section of the furnace chamber, causing the water content to evaporate. The residues are then transported to a degassing section where they are degassed at higher temperatures. Subsequently, the pre-treated residues enter the actual combustion chamber, where they are burned substoichiometrically at temperatures of approximately 800°C to 1150°C. Finally, the remaining combustion takes place in the last grate section.

[0004] Primary air is supplied from below the grate, and secondary air is supplied from above, both influencing the combustion process and the course of the chemical reactions that occur. The air volume is typically metered to achieve thorough combustion with low nitrogen oxide formation.

[0005] During afterburning, secondary air is supplied to combust the gases from the main combustion zone, such as carbon monoxide or hydrocarbons. At the end of the combustion process, the remaining combustion residues, also called slag, fall into a water bath at the grate end, from which they are removed by rams or chain scrapers. Finally, the slag is conveyed to the slag processing plant.

[0006] High combustion temperatures can lead to significant thermal and resulting mechanical stresses and wear on the grate bars themselves and the grate coating on them. To counteract this problem, conventional methods involve cooling the grate coating by directing air through funnels positioned below the grate, or by using combustion air forced into the combustion chamber through a space formed by the grate bars and a baffle plate. However, these methods of cooling the grate coating are dependent on the amount of combustion air. Therefore, the cooling capacity depends on the available amount of combustion air. Furthermore, the air outlets of the grate into the combustion chamber can become blocked by residual material such as ash, metals, or slag, thus preventing or reducing cooling.

[0007] As an alternative to air cooling, liquid cooling of the grate can also be installed. For example, coolant is circulated through channels within the grate. The heated coolant then passes through a heat exchanger, where the heat energy is dissipated. Traditionally, cooling pipe systems are often installed within the grate, running essentially lengthwise along the grate bar and parallel to each other. Transverse pipes, running widthwise, are often used to connect adjacent cooling pipes. However, this arrangement has the disadvantage that, firstly, the surface of the grate bar is not cooled uniformly, and secondly, stress cracks can occur when the transverse pipes heat up.The aforementioned stress cracks can lead to leaks in the cooling system pipes, causing coolant to escape and potentially disrupting or even interrupting the cooling circuit.

[0008] To eliminate the risk of stress cracking, EP 1 315 936 B1 proposes integrating a cooling coil into a grate bar. This coil comprises longitudinally running pipes, each of which is curved downwards towards the support area in a nose section and joined there to form a cooling coil by transverse connections, which, however, only connect two directly adjacent pipes in pairs (see [reference]). Fig. 1) However, a disadvantage of this arrangement is the uneven distribution of the coolant temperature from one side to the other of the grate bar (viewed in the lateral direction), since colder coolant flows in and is heated on one side, only reaching the other side last. The resulting temperature gradient can, in turn, be detrimental to the grate bar.

[0009] EP 0 989 363 A1 describes a grate block for a plant for the thermal treatment of waste, comprising a substantially rectangular body with a longitudinally defined orientation and a cast-in, meandering tube. A section of the tube is arranged laterally within the grate block, running longitudinally. A fluid, preferably water, is used as the coolant, flowing through the tube to cool the grate block.

[0010] DE 197 53 981 C2 describes a water-cooled grate plate, intended in particular for waste incineration furnaces, which has at least one coolant channel. This channel serves to cool the upper surface of the grate plate. The coolant channel has a coolant connection located in a central area of ​​the grate plate. It is essential that the coolant connection is located approximately centrally between the two flanks of the grate plate, and may be offset towards one end of the grate plate.

[0011] EP 0 924 464 A1 describes a grate bar for forming a grate in combustion plants, which has a loop-shaped channel for the passage of cooling air. The cooling air exiting at the outlet opening is preferably introduced directly into the space below the grate bar. There, it flows around the underside of the grate bar and preferably around projecting cooling fins, with renewed cooling effect, before being directed upwards through a slot at the free end of the grate bar into the combustion chamber as intake air.

[0012] It is therefore an object of the present invention to develop a grate rod with a cooling system with an improved temperature distribution.

[0013] This problem is solved by a grate bar according to claim 1, by a combustion grate according to claim 11, by a combustion furnace according to claim 12 and by a method for producing a grate bar for a combustion furnace according to claim 13.

[0014] The grate bar according to the invention for a combustion furnace has a surface that faces a combustion chamber during operation. This surface serves as a receiving and transport surface for the fuel. Furthermore, the grate bar according to the invention comprises a rear support area designed for resting on a grate support. The support area can, for example, also include retaining elements for mounting on a grate support and / or for mounting several grate bars parallel to one another. The grate bar according to the invention also comprises a front area, which includes a grate bar front and a support area formed on the underside of the grate bar. As will be explained later, the fuel is conveyed via the grate bar front to the next serially positioned grate bar. The aforementioned support area serves to rest the grate bar on the next serially positioned grate bar.The grate bar according to the invention also comprises a coolant channel integrated in the grate bar with a cooling coil extending from a first coolant connection to a second coolant connection, wherein the cooling coil runs in the front area, preferably in a substantially U-shaped, stepped, nested arrangement.

[0015] A cooling coil is defined as a cooling pipe system that runs at least partially in a serpentine pattern. In this context, "stepped and nested" means that at least some of the sections of the cooling coil located at the front, each forming a kind of reverse section of a corresponding section of the cooling coil positioned at the front, curve around a common central area or center. However, the reverse sections of the cooling coil have different dimensions, such that the smaller reverse sections run inside the larger ones. This means that the outer reverse sections of the cooling coil are arranged around the inner reverse sections.The nested arrangement of the cooling coil allows successive cooling coil sections to be positioned on different sides relative to the longitudinal axis (or a median plane running along the longitudinal axis and perpendicular to the surface of the grate bar) of the grate bar, resulting in a more uniform heat distribution in the transverse direction of the grate bar. The transverse direction is defined as perpendicular to the longitudinal and vertical directions of the grate bar, with these terms referring to the intended arrangement of the grate bar within a grate.

[0016] The grate according to the invention has a number of grate steps arranged one above the other in a tile-like fashion, each step having several grate bars arranged parallel to one another, wherein at least some of the grate bars are grate bars according to the invention. The grate bars according to the invention are thus preferably part of a grate, wherein they are positioned both next to one another or parallel to one another and are also arranged serially in steps, so that the entire grate has a certain gradient that can be used for the transport of the fuel.

[0017] The combustion furnace according to the invention, which can in particular be a combustion furnace for solid fuel combustion, comprises a combustion chamber which has the combustion grate according to the invention in a lower area.

[0018] In the inventive method for manufacturing a grate bar for a combustion furnace, a grate bar is produced with a surface that faces a combustion chamber during operation. A rear support area for resting on a grate support is formed on the grate bar. Furthermore, a front area is formed on the grate bar, comprising a grate bar front and a support area formed on the underside of the grate bar. In addition, a coolant channel with a cooling coil extending from a first coolant connection to a second coolant connection is integrated into the grate bar. The cooling coil is arranged in a nested configuration in the front area, preferably in a substantially U-shaped manner. Preferably, the grate bar, together with its support area and front area, can be manufactured in one piece in a casting process, with the coolant channel being integrated or cast in simultaneously. The coolant channel, orThe cooling coil can first be formed from a pipe or assembled pipe sections and then cast in place as such. However, it is also possible to simply create the coolant channel or cooling coil by means of corresponding cavities in the casting.

[0019] The dependent claims and the following description each contain particularly advantageous embodiments and further developments of the invention. In particular, the claims of one claim category may also be further developed analogously to the dependent claims of another claim category. Furthermore, within the scope of the invention, the various features of different embodiments and claims may also be combined to form new embodiments.

[0020] In an advantageous embodiment of the grate bar according to the invention, the cooling coil in the front region extends in at least three stages, each nested within the other. That is, the individual head sections of the cooling coils, while similarly shaped, have different dimensions, with the larger head sections encompassing the smaller head sections. As a result of this particular arrangement of the cooling coil sections, a further improved heat distribution across the width of the grate bar, i.e., in the transverse direction, can be achieved.

[0021] In a particularly advantageous embodiment, the cooling coil is designed such that the flow direction of the coolant flowing through the cooling coil reverses between successive adjacent stages. This reversal of the flow direction in adjacent stages results in an even more uniform temperature distribution across the width of the grate bar.

[0022] In a preferred embodiment of the grate bar according to the invention, the cooling coil has cooling coil sections that are angled downwards towards the support area in the front region. Due to the angled shape of the cooling coil, it can also extend down to the support area of ​​the grate bar in the region of the end face. With this particular arrangement, good cooling with a more uniform temperature distribution is ensured even in the region of the end face of the grate bar.

[0023] The cooling coil sections are particularly favorably rounded in the area of ​​the bend at the front. This results in a particularly favorable flow behavior of the cooling medium in the front area.

[0024] In a specific embodiment, the grate bar according to the invention comprises a nose section rounded between a top surface and a front surface. Alternatively, the grate bar can also have an angular shape at the front edge between the top surface and the front surface, or simply a small chamfer in the usual manner. The more uniform temperature distribution achieved with the invention is particularly relevant with a more angular front edge, as the front edge becomes hotter than with a rounded nose.

[0025] In the grate bar according to the invention, the coolant channel has several parallel longitudinal cooling coil sections extending longitudinally from the rear support area to the front area. Each of these longitudinal cooling coil sections is connected in the front area of ​​the grate bar to another longitudinal cooling coil section, i.e., the next longitudinal cooling coil section in the flow path (but, as will be explained later, not necessarily spatially adjacent), via a head cooling coil section extending transversely to the longitudinal direction.

[0026] Preferably, at least some of the longitudinal cooling coil sections are connected to an indirect neighbor via a head cooling coil section. In this context, an indirect neighbor is understood to be a neighbor two steps ahead or even further away, for example, a neighbor two steps ahead. Adjacent longitudinal cooling coil sections are defined as adjacent, preferably parallel, longitudinal cooling coil sections. Thus, preferably, some of the longitudinal cooling coil sections are not directly connected to the nearest neighbor, but to a longitudinal cooling coil section positioned further away in the lateral direction. This type of arrangement takes into account the fact that successive, directly connected longitudinal cooling coil sections exhibit relatively similar temperature values.By ensuring that successive longitudinal cooling coil sections are spatially separated from one another in the transverse direction, a linear or at least monotonic temperature profile of the coolant in the cooling coil is prevented in the transverse direction. In this way, a more balanced temperature distribution in the grate bar is achieved in the transverse direction.

[0027] Preferably, in the front region of the grate bar according to the invention, a longitudinal cooling coil section located in a first longitudinal half-side of the grate bar – relative to a central plane extending longitudinally along the grate bar – can be connected via a head cooling coil section to a longitudinal cooling coil section located in the second longitudinal half-side of the grate bar. This results in a connection of cooling coil sections located in different longitudinal half-sides, i.e., one section is located on one side of the longitudinal axis of the grate bar and the other section is located on the opposite side of the longitudinal axis of the grate bar. In this way, it is ensured that successive cooling coil sections with similar temperature values ​​are arranged opposite each other.

[0028] Preferably, at least one of the coolant connections of the grate bar is arranged in the rear support area.

[0029] In a particular embodiment of the grate bar according to the invention, at least one of the coolant connections extends substantially vertically (i.e., only at a small angle of max. 5°), preferably exactly perpendicularly, downwards to the longitudinally extending cooling coil sections. Such a vertical downward branching of the coolant connections allows the cooling coil to run parallel to the surface of the grate bar over a large length of the grate bar. In this way, it is ensured that the surface of the grate bar in the load-bearing area is also sufficiently cooled, since the cooling coil can continue parallel to the surface of the grate bar until it bends downwards due to the vertical arrangement of the coolant connection.

[0030] In the grate bar according to the invention, the cooling coil has a first longitudinal cooling coil section. The first longitudinal cooling coil section extends from the first coolant connection in the rear support area in a central region with respect to the width of the grate bar, i.e., not at the outer edge, to the front area, preferably to an outer end of the front area. Furthermore, the first longitudinal cooling coil section is connected at the top, i.e., remaining in the plane of its path, in the front area via a first head cooling coil section to a second longitudinal cooling coil section, forming an internal reversal step. This second longitudinal cooling coil section extends in the opposite direction, antiparallel and adjacent to the first longitudinal cooling coil section, from the front area back to the rear support area. The two first and second longitudinal cooling coil sections and the first head cooling coil section thus form a first U-shaped reversal section.an internal reversing stage in which the direction of the cooling coil reverses.

[0031] The second longitudinal cooling coil section is connected to a third longitudinal cooling coil section in the rear support area. The third longitudinal cooling coil section runs in the opposite direction and antiparallel to the second longitudinal cooling coil section along a first longitudinal outer surface of the grate bar, with a sixth longitudinal cooling coil section located between the second and third longitudinal cooling coil sections. The second and third longitudinal cooling coil sections together encircle the sixth longitudinal cooling coil section, with the third longitudinal cooling coil section running from the rear support area to the front area.

[0032] The third longitudinal cooling coil section is connected to a fourth longitudinal cooling coil section via a second head cooling coil section, forming an outer reversing stage. The fourth longitudinal cooling coil section runs from the front area along a second longitudinal outer surface of the grate bar, which is opposite the first longitudinal outer surface of the grate bar, back to the rear support area.

[0033] The two third and fourth longitudinal cooling coil sections and the second head cooling coil section in the front area form a second U-shaped reversing section as an outer reversing stage, which encloses the first reversing section and a third reversing section located between the first and second reversing sections. The third reversing section is also oriented perpendicular to the longitudinal direction of the grate bar and parallel to the end face of the grate bar.

[0034] The fourth longitudinal cooling coil section is connected in reverse to a fifth longitudinal cooling coil section in the rear wing area. This fifth longitudinal cooling coil section runs in the opposite direction, antiparallel and adjacent to the fourth longitudinal cooling coil section, from the rear wing area to the front area. The fifth longitudinal cooling coil section is connected via a third head cooling coil section, forming a central reversal stage, to the aforementioned sixth longitudinal cooling coil section, which runs from the front area to the second coolant connection in the rear wing area.

[0035] The fifth longitudinal cooling coil section, the sixth longitudinal cooling coil section and the third head cooling coil section in the front area form a U-shaped reversing section as a middle reversing stage, which is again oriented perpendicular to the longitudinal direction of the grate bar and parallel to the front face of the grate bar, enclosing the inner U-shaped reversing section and being enclosed by the outer U-shaped reversing section.

[0036] Particularly preferred are the third to sixth longitudinal cooling coil sections in the front area angled downwards towards the support area, so that the inner reversing step is at the top, i.e. towards the side facing away from the support side, and the outer, i.e. the second head cooling coil section is located just above the support area and the middle, i.e. the third head cooling coil section is arranged approximately halfway between the upper edge and the lower edge of the front area.

[0037] The invention is explained in more detail below with reference to the accompanying figures and exemplary embodiments. The same components are designated with identical reference numerals in the various figures. They show: Fig. 1. A perspective view of a grate bar with a cooling coil system according to the state of the art, Fig. 2 a perspective view of a grate bar with a cooling coil system according to a first embodiment of the invention, Fig. 3 a side view of the in Fig. 2 shown rust bars, Fig. 4 a front view of the in Fig. 2 shown rust bars, Fig. 5 a perspective view of a grate bar according to a second embodiment of the invention, Fig. 6 A perspective view of three grate stages of a furnace grate, which grate bars according to the Fig. 1 Fig. 7 a simplified sectional view through a solid fuel combustion plant with a combustion grate consisting of grate stages according to Fig. 6 is built.

[0038] Fig. Figure 1 shows a perspective view of a grate bar 10 with an integrated, cast-in coolant channel containing a cooling coil running in a serpentine pattern. Individual grate bars 10 can be arranged side by side to form a movable grate for use in an incineration plant. The rear end T of the grate bar 10 is designed as a support area T with cup-shaped bushings. Appropriately designed pins of the grate frame of an incineration plant can engage in these bushings in a manner known per se. The front end F of the grate bar 10 has a rounded edge N, also referred to as a nose, as a continuation of the upper combustion surface. The pins of the grate frame of the incineration plant are spaced such that grate bars placed on them overlap in a staggered, scale-like manner. That is to say,The bearing surfaces located below the nose F rest on the surfaces of the following grate bars.

[0039] Furthermore, in Fig. Figure 1 shows the cooling coil L of the grate bar 10. A liquid coolant flows through the cooling coil, entering the cooling channel L through a coolant inlet KE, passing through the channel, and then exiting the cooling coil via the coolant outlet KA. The cooling coil comprises straight pipe segments extending from the support area T of the grate bar 10 parallel to the side edge and longitudinally R parallel to the surface O to the nose N. In the nose area, these cooling coil sections curve downwards towards the bearing surface of the grate bar, corresponding to the bend of the nose N. That is, in the nose area or the front area F, the longitudinally extending cooling coil sections are curved downwards, as is also the case in Fig. As can be seen in Figure 1. At the lower end of the nose N, i.e., in the area of ​​the bearing surface of the grate bar 10, the ends of two adjacent longitudinal cooling coil sections are connected in pairs via a short transverse pipe section K. In the rear area T of the grate bar 10, the ends of the longitudinal cooling coil sections are each connected via a curved pipe section, so that a continuous closed cooling coil with an inlet KE and an outlet KA is formed.

[0040] In the Fig. Figures 2 to 4 show a grate bar 20 according to a first embodiment of the invention viewed from different directions. Here, in the Fig. 2. The rust rod is drawn as a perspective view from a slanted top view, in Fig. Figure 3 shows the grate bar 20 as a side view and in Fig. Figure 4 illustrates a front view of the grate bar 20.

[0041] The grate bar 20 according to a first embodiment of the invention, similar to the conventional grate bar 10, comprises a rear support area T in which brackets for a support element, such as an axle element or similar suspensions, can optionally be arranged. The grate bar 20 also has a central area with a surface O serving as a combustion surface, on which the fuel rests or is conveyed during the combustion process. Furthermore, the grate bar 20 also comprises a front area F, the front of which V is oriented approximately perpendicular to the surface O, and the transition between the front surface and the surface O is formed by a chamfer Fa, which is oriented at an angle of approximately 45° to the surface O and the front surface. Naturally, the orientation and dimensions of the chamfer can vary depending on the specific embodiment.Through holes 12 running transversely to the longitudinal direction R in hooks 11 in the rear support area T, adjacent grate bars 20 can be screwed together so that the entire grate bars of a grate step form a solid connection (see also . Fig. 6).

[0042] The grate bar 20 also includes a cooling system with a cooling coil L. The cooling coil L has cooling coil sections L1, L2, L3, L4, L5, L6, also called "longitudinal cooling coil sections," extending longitudinally R from the rear support area T to the front area F beneath the surface O in the longitudinal direction of the grate bar R, and arranged parallel to each other. A first coolant connection KA1 and a second coolant connection KA2 are also located in the rear support area T. Without loss of generality, the first coolant connection KA1 can, for example, function as a coolant inlet and the second coolant connection KA2 as a coolant outlet.

[0043] As in Fig. As can be seen in Figure 3, the coolant connections KA1 and KA2 run vertically, i.e., perpendicular to the longitudinal cooling coil sections L1, L2, L3, L4, L5, and L6. As already mentioned, a perpendicular bend of the coolant connections KA1 and KA2 relative to the longitudinal cooling coil sections L1, L2, L3, L4, L5, and L6 has the advantage that the coolant connections KA1 and KA2 require less space with regard to the surface area O of the grate bar 20. In other words, due to their vertical orientation, the coolant connections KA1, KA2 do not take up any space below the surface of the grate bar 20 for the longitudinal cooling coil sections L1, L2, L3, L4, L5, L6. Therefore, the longitudinal cooling coil sections L1, L2, L3, L4, L5, L6 extend below a very large area of ​​the total surface O of the grate bar 20, even towards the rear, thus enabling uniform cooling of the grate bar 20. As shown in Fig. As can be seen in Figure 2, the cooling coil L, or the longitudinal cooling coil sections L1, L2, L3, L4, L5, L6 that form it, run from the rear support area T to the front area F, where they reverse direction and run back to the rear support area T.

[0044] In the front area F, reversing areas or head cooling coil sections K1, K2, K3 extend in the direction of the width of the grate bar 20, in other words in the transverse direction, which each connect two longitudinal cooling coil sections L1, L2, L3, L4, L5, L6.

[0045] While the first head cooling coil section K1, which connects the first longitudinal cooling coil section L1 with the second longitudinal cooling coil section L2, runs in the nose area or front area F in the same plane as the first longitudinal cooling coil section L1 and the second longitudinal cooling coil section L2, the third longitudinal cooling coil section L3 and the fourth longitudinal cooling coil section L4 bend downwards towards the support area AB in the front area F, then each run vertically for a short distance, i.e. perpendicular to the parts of the longitudinal cooling coil sections L1, L2, L3, L4, L5, L6 that run parallel to the surface, and are then connected horizontally via a second head cooling coil section K2, which runs just above the support area AB.

[0046] A third head cooling coil section K3 connects the fifth longitudinal cooling coil section L5 and the sixth longitudinal cooling coil section L6 and runs in the front area F between the first head cooling coil section K1 and the second head cooling coil section K2. For this purpose, the fifth longitudinal cooling coil section L5 and the sixth longitudinal cooling coil section L6 also bend downwards in the front area F, i.e., towards the support area AB, and then run vertically for a short distance, i.e., perpendicular to the parts of the longitudinal cooling coil sections L1, L2, L3, L4, L5, L6 that run parallel to the surface, but only to approximately the middle of the vertical, i.e., in the vertical direction at about the middle height between the transverse connection by the first head cooling coil section K1 and the transverse connection by the second head cooling coil section K2.

[0047] In the rear support section T, the cooling coil L has two rear reversing sections H1 and H2, with both the first rear reversing section H1 and the second rear reversing section H2 running in the plane formed by the longitudinal cooling coil sections L1, L2, L3, L4, L5, and L6. The first rear reversing section H1 connects the second longitudinal cooling coil section L2 with the third longitudinal cooling coil section L3, and the second rear reversing section connects the fourth longitudinal cooling coil section L4 with the fifth longitudinal cooling coil section L5.

[0048] Unlike the arrangement in Fig. 1 In the grate bar 20 according to the invention, the transverse connection of the longitudinal cooling coil sections L1, L2, L3, L4, L5, L6 in the front area F involves a crossing of the vertical mean longitudinal plane, so that, assuming a continuous temperature profile, for example a linear temperature profile depending on the distance traveled by the coolant in the cooling coil L, a more uniform cooling effect is achieved in the width direction of the grate bar, which leads to a more balanced temperature distribution.

[0049] It should be noted that the positions of the individual longitudinal cooling coil sections L2, L3, L4, L5, when numbered (first, second, third,... longitudinal cooling coil section) with respect to the flow direction of the cooling medium, differ from those of the Fig. The conventional arrangement shown in 1 is in most cases completely different. For example, in the one shown in Fig. In the arrangement shown in Figure 2, the second longitudinal cooling coil section L2 is located to the right of the center, near the central longitudinal axis, whereas in the conventional arrangement, the second longitudinal cooling coil section is located 10 in Fig. 1 is positioned on the far left edge. Conversely, in the arrangement 20, it is located in Fig. 2 the third longitudinal cooling coil section L3 on the far right edge of the arrangement, whereas in the conventional arrangement the third longitudinal cooling coil section 10 in Fig. 1 is located in the middle. Furthermore, in the conventional arrangement 10, the fourth longitudinal cooling coil section is positioned slightly to the right of the center, while in arrangement 20 it is located in Fig. 2 is positioned on the left edge of the grate bar 20. The position of the fifth longitudinal cooling coil section in the conventional grate bar 10 in Fig. 1 is on the right edge, while the fifth longitudinal cooling coil section L5 is the second from the left. Only the first longitudinal cooling coil section L1 and the sixth longitudinal cooling coil section L6 are in the same position in the grate bar 20 according to the embodiment of the invention as in the known grate bar 10. Fig. 1, since the position of the two coolant connections KA1, KA2 is very similar or even the same in both cases.

[0050] In Fig. Figure 5 shows a grate bar 30 according to a second embodiment of the invention. The grate bar 30 according to the second embodiment differs from the grate bar 20 according to the first embodiment in that, in the front region F, the longitudinal cooling coil sections L3, L4, L5, L6 of the cooling coil L do not curve downwards towards the second and third head cooling coil sections K2, K3, but rather form an angular, optionally right-angled bend. In this configuration of the cooling coil in the front region F, the geometry of the cooling coil L in the area of ​​the chamfer FA in the front region is even more closely adapted to the contour of the surface or the outer shape of the grate bar, so that the distance of the cooling coil L to the surface O remains approximately the same even at the edge or chamfer FA in the front region F.

[0051] In Fig. Figure 6 shows a perspective view of a section of three grate stages 51, 52, 53 of a finished stoker grate 50. As can be seen, the support area T is not directly exposed to the combustion chamber 62, since the rear section of a grate bar 20 in a grate stage 52, 53 is covered by the grate bars 20 of the grate stage 51, 52 above it. Only the front section 2A protrudes from under the grate bar 20 above it. Therefore, this area is cooled during operation by a coolant flowing through the coolant channel according to the invention. For this purpose, the coolant connections KA1, KA2 are connected to cooling lines (not shown) that run under the stoker grate 50 to a coolant supply system with pumps, heat exchangers, etc. In the simplest case, water can be used as the coolant. However, other liquids or fluids, including gases, can also be used.

[0052] The cooling coils L in the grate bars 20 are here as in the Fig. 2 to 4 designed. In addition, the grate bars 20 are provided here with a rounded nose N at the upper front edge.

[0053] As in Fig. As shown schematically in Figure 6, the individual grate bars 20 of a grate step 51, 52, 53 are each mounted together with the hooks 11 of the retaining section T of the grate bar base body 2 on a bearing rod 54 running perpendicular to the longitudinal direction R of the grate bars 20 as a grate support 54. Through holes 12 running transversely to the longitudinal direction R (see Figure 6), Fig. 2) Adjacent grate bars 20 can be screwed together in the hooks 11, so that all the grate bars of a grate step 51, 52, 53 form a fixed assembly supported on the respective bearing rod 54. Every second bearing rod 54, here the bearing rod 54 of the middle grate step 52, is coupled to a mechanism (not shown) by which the bearing rod 54 can be moved in a direction B parallel to the longitudinal direction R of the grate bar (see Fig. 2) can be moved back and forth, so that the entire grate stage 52 is pushed back and forth in the direction of movement B. The associated cooling lines are accordingly designed to be sufficiently flexible. In this way, the fuel bed is transported diagonally downwards from grate stage to grate stage in the transport direction Tr. This movement of every second grate stage 52 also leads to a mechanical load, since the grate bars 52 of an upper grate stage slide back and forth with their front bearing area AB on the surface O of the grate stage below.

[0054] A furnace grate constructed from such grate stages 51, 52, 53 with the grate bars 1 according to the invention can then, as in Fig. Figure 7 shows the system being used in a solid fuel combustion plant 60. The grate 50 is located at the bottom of the combustion chamber 62. The solid fuel to be burned is continuously fed into this combustion chamber 62 via a feed chute 61. During combustion, the fuel bed in the combustion chamber 62 is continuously transported diagonally downwards over the grate 50 by the feed movements of every second grate stage. The upper area of ​​the grate 50, facing the feed chute 61, is a drying and degassing zone, the main combustion takes place in the middle area, and the secondary combustion occurs in the lower area.

[0055] Below the grate 50 are funnel-shaped ash collectors 66, which collect the ash produced during combustion, which falls, among other places, through the air slots between the grate bars, and feed it to subsequent conveying devices 67. At the lower end of the grate is a slag conveying device 69. The ash and slag are further disposed of by suitable equipment, which is not shown in detail here. Above the combustion chamber 62 are boiler passes through which the flue gas is routed so that it transfers its energy to the heating surfaces of the boiler passes. The cooled flue gas is then passed through a filter system 64, which is only shown schematically, and the filtered flue gases then exit the solid fuel combustion plant 60 via an outlet 65. It is expressly pointed out that the solid fuel combustion plant in Fig.Figure 7 is only shown very roughly schematically, since the structure of such solid fuel combustion plants is known in principle to those skilled in the art and the further components, in particular the facilities for collecting and disposing of the ash and slag, for filtering the flue gases and for feeding the fuel into the combustion plant, are not essential for the invention.

[0056] Finally, it should be noted once again that the grate bars and grate bar stages described above, as well as the fire grate and the combustion plant, are merely exemplary embodiments which can be modified in various ways by a person skilled in the art without leaving the scope of the invention.

[0057] For the sake of completeness, it should also be noted that the use of the indefinite articles “ein” or “eine” does not preclude the possibility that the characteristics in question may be present multiple times. Reference symbol list 2A Front section 10 conventional grate bars 11 hooks 12 holes 20 rust rods 30 rust rods 50 Fire grate 51, 52, 53 grate levels 54 Grating support / bearing rod 60 Solid fuel combustion plant 61 Feed shaft 62 Combustion chamber 64 filter system 65 Outlet 66 funnel-shaped ash collectors 67 funding institutions 69 Slag conveying device AB print area B Direction of movement F front end of the grate bar / front area Fa Fase H1, H2 rear reversing areas HS1 Long half-side K transverse short pipe section K1, K2, K3 head cooling coil sections KA coolant outlet KA1 first coolant connection KA2 second coolant connection KE coolant inlet L Cooling coil / coolant channel L1, L2, L3, L4, L5, L6 Longitudinal cooling coil sections N Nose Surface R Longitudinal direction V Front T carrying area Direction of transport

Claims

[1] Grate bar (20, 30) for an incineration furnace with - a surface (O) which, during operation, faces a combustion chamber (62), - a rear support area (T) designed to rest on a grid support (54) and - a front area (F) comprising a grate bar front (V) and a support area (AB) formed on an underside of the grate bar (20, 30), as well as - a coolant channel (L) integrated in the grate bar (20, 30) with a cooling coil (L) extending from a first coolant connection (KA1) to a second coolant connection (KA2), wherein the cooling coil (L) extends in the front region (F), preferably in a substantially U-shaped, stepped, nested arrangement, wherein the coolant channel (L) has several longitudinal cooling coil sections (L1, L2, L3, L4, L5, L6) which extend parallel to each other in a longitudinal direction (R) extending from the rear support region (T) to the front region (F), wherein the longitudinal cooling coil sections (L1, L2, L3, L4, L5, L6) each connect in the front region (F) of the grate bar (20, 30) via a head cooling coil section (K1, K2, K3) extending transversely to the longitudinal direction (R) to another longitudinal cooling coil section (L1, L2, L3, L4, L5, L6) are connected - wherein the cooling coil (L) has a first longitudinal cooling coil section (L1) which runs from the first coolant connection (KA1) in the rear support area (T) in a central area with respect to the width of the grate bar (20, 30) to the front area (F) and in the front area (F) is connected via a first head cooling coil section (K1) to a second longitudinal cooling coil section (L2) which runs in the opposite direction antiparallel and adjacent to the first longitudinal cooling coil section (L1) from the front area (F) back to the support area (T), and - wherein the second longitudinal cooling coil section (L2) in the support area (T) is connected to a third longitudinal cooling coil section (L3) which runs in the opposite direction and antiparallel to the second longitudinal cooling coil section (L2) on a first longitudinally extending outer side (R) of the grate bar (20, 30), wherein a sixth longitudinal cooling coil section (L6) is located between the second longitudinal cooling coil section (L2) and the third longitudinal cooling coil section (L3), and - wherein the third longitudinal cooling coil section (L3) is connected via a second head cooling coil section (K2) forming an outer reversing stage to a fourth longitudinal cooling coil section (L4), which runs from the front area (F) on one of the first longitudinal outer sides of the grate bar (20, 30) opposite the second longitudinal outer side to the support area (T), - wherein the fourth longitudinal cooling coil section (L4) in the support area (T) is connected to a fifth longitudinal cooling coil section (L5) which runs in the opposite direction antiparallel and adjacent to the fourth longitudinal cooling coil section (L4) from the support area (T) to the front area (F), and - wherein the fifth longitudinal cooling coil section (L5) is connected via a third head cooling coil section (K3) forming a middle reversal stage to a sixth longitudinal cooling coil section (L6) which runs from the front area (F) to the second coolant connection (KA2) in the support area (T). [2] Grate bar (20, 30) according to claim 1, wherein the cooling coil (L) in the front area (F) is nested in a step-like manner at least three times. [3] Grate rod (20, 30) according to claim 1 or 2, wherein the cooling coil (L) is designed such that the flow direction of a coolant flowing through the cooling coil (L) reverses between successive adjacent stages. [4] Grating rod (20, 30) according to one of the preceding claims, wherein the cooling coil (L) has cooling coil sections (L3, L4, L5, L6,) which are angled downwards in the front area (F) towards the support area (AB). [5] Grate bar (20, 30) according to claim 4, wherein the cooling coil sections (L3, L4, L5, L6,) are rounded in the area of ​​the bend in the front area (F). [6] Grating bar (20, 30) according to one of the preceding claims, comprising a nose area (N) rounded between a top and the front (V). [7] Grate bar (20, 30) according to one of the preceding claims, wherein at least a part of the longitudinal cooling coil sections (L3, L4, L5, L6,) are connected via a head cooling coil section (K1, K2, K3) to an indirect neighbor (L3, L4, L5, L6,). [8] Grate bar (20, 30) according to one of the preceding claims, wherein in the front region (F) a longitudinal cooling coil section (L1, L4, L5), which is located in a first longitudinal half-side (HS1) of the grate bar (20, 30) with respect to a central plane (M) extending in the longitudinal direction (R) of the grate bar (20, 30), is connected via a head cooling coil section (K1, K2, K3) to a longitudinal cooling coil section (L2, L3, L6), which is located in the second longitudinal half-side (HS1) of the grate bar (20, 30). [9] Grate bar (20, 30) according to one of the preceding claims, wherein at least one of the coolant connections (KA1, KA2) is arranged in the rear support area (T). [10] Grate bar (20, 30) according to one of the preceding claims, wherein at least one of the coolant connections (KA1, KA2) extends downwards substantially perpendicular to the longitudinal cooling coil sections (L1, L2, L3, L4, L5, L6) extending in the longitudinal direction (R). [11] Fire grate (50) with a number of grate steps (51, 52, 53) arranged one above the other in a tile-like manner, each of which has several grate bars (20, 30) arranged parallel to each other, wherein at least a part of the grate bars (20, 30) are designed according to one of claims 1 to 10. [12] Combustion furnace (60), in particular for solid fuel combustion, with a combustion chamber (62) which has a stoking grate (50) in a lower area according to claim 11. [13] Method for producing a grate bar (20, 30) for a combustion furnace (60) according to any one of the preceding claims 1 to 10, in which a grate bar (20, 30) is produced with a surface (O) which in operation faces a combustion chamber (62), a rear support area (T) for resting on a grate support (54) and a front area (F) which comprises a grate bar front (V) and a support area (AB) formed on a bottom side of the grate bar (20, 30), wherein a coolant channel (L) with a cooling coil (L) extending from a first coolant connection (KA1) to a second coolant connection (KA2) is integrated into the grate bar (1), wherein the cooling coil (L) is arranged in the front area (F), preferably in a substantially U-shaped, nested manner.

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