Combustion grate for an incinerator at a waste incineration plant

Abstract

Combustion grid including a tensioning device (30) for a row (16) of grid blocks (18) arranged in the combustion grid (10), the tensioning device (30) being designed to maintain the alignment of the row of grid blocks.The tensioning device comprises a cable (70) having a first end zone (70a) and a second end zone (70b) opposite the first end zone (70a), a first connection means (40) for connecting the first end zone of the cable (70a) to a side wall (14a) of a first edge zone of the combustion grate laterally bordering the combustion grate, and a second connection means (50) for connecting the first end zone of the cable (70b) to a side wall (14a) of a first edge zone of the combustion grate laterally bordering the combustion grate, and a second connection means (50) for connecting the second end of the cable (70b) to a side wall (14b) of a second edge zone opposite the first edge zone and laterally bordering the combustion grate. [Fig. 2].

Description

Title of the invention: Combustion grate for an incinerator in a waste incineration plant

[0001] The present invention relates to a combustion grate for an incinerator in a waste incineration plant in which waste is used as a fuel source to typically generate steam for the production of electrical power.

[0002] The combustion grate provides the necessary support for the waste as it is transported through the combustion sequence. Typically, the combustion grate can be of the reciprocating, forward-moving type, with grate blocks inclined at an angle and alternating transverse rows, viewed with respect to the direction of waste flow, also called the transport direction, of stationary and reciprocating grate blocks. Each row of grate blocks overlaps the preceding row to form the combustion grate. The alternating rows that move back and forth are supported by a movable structure that ensures the reciprocating motion. Attachment to a fixed or movable guide is made at the rear of the grate blocks, below the preceding overlapping block.

[0003] Combustion grates are generally made up of rows of grate blocks and include pressure plates defining the lateral sides of the combustion grate, the pressure plates being arranged on each side of the rows.

[0004] Maintaining the alignment of each row of grid blocks, that is, maintaining the alignment of the grid blocks in a direction perpendicular to the direction of transport, requires that the grid blocks be fitted tightly next to each other. This tight fit also contributes to good air distribution by avoiding gaps between the grid blocks, so that the supplied air is forced only into the air supply channels configured to provide air to the waste bed. The tight fit is generally ensured by at least one tension bar located under each row of grid blocks. In reciprocating rows, the tension bar is attached at each end to the corresponding lateral grid block in those rows.In stationary rows, each end of the tension bar is fixed to one of the two pressure plates that define the lateral sides in relation to the waste flow from the combustion grate. Alternatively, each end of the tension bar can be fixed to the corresponding lateral grate block in these rows, the lateral grate blocks being screwed to the pressure plates.

[0005] The tension bar is essentially a solid metal bar with a tensioner at the other end. Preferably, the tension bar is located approximately halfway along each row of grate blocks, allowing it to be tightened to a predetermined torque to achieve the desired tension under operating conditions. However, the tension bar is manually set to the predetermined tension when the combustion grate is cold. During operation, the tension bar is cooled by the combustion air circulating under the combustion grate, while the combustion grate is subjected to temperatures relative to the fire above it. Consequently, the tension bars can still reach temperatures of up to 400°C or higher.Consequently, the tension bars are highly sensitive to various operating conditions, for example, expanding during operation or contracting when the furnace is shut down. Defining the appropriate tension for mounting the tension bars remains a difficult task, particularly because the failure of a tension bar would cause the entire row of grid blocks to lift and necessitate a shutdown for repair.

[0006] US patent 5377663A discloses grid blocks that mitigate or eliminate clogging of air holes on the front face of the grid blocks. The grid blocks are clamped by a tension bar consisting of two sections. A first section includes a head end inserted through a hole in one side of a lateral grid block in a row of grid blocks and an end opposite the head end. The opposite end has a threaded portion that engages with a tensioner. A second section includes another head end inserted through a hole in one side of another lateral grid block disposed at the opposite end of the row of grid blocks and an end opposite the other head end, the opposite end also having a threaded portion that engages with the tensioner. When mounted, the tensioner is rotated to increase or decrease the tension on the tension bar.Each section of the tension bar also includes a midsection, which is replaced by a spring section to better accommodate the stresses within the tension bar and the varying conditions in plant operations that can slowly or abruptly alter the tension on the bar. The tension bar comprises several components that must be adjusted to each other because they are made of different materials that expand differently under the influence of heat. In particular, the springs can lose their elasticity over time and require maintenance of the combustion grate. The components may also react differently to corrosion, which can lead to additional maintenance work.

[0007] WO 2011 / 063912A1 discloses a waste disposal installation in which waste deposited on a combustion grate is burned, said combustion grate comprising at least one handling unit formed by several grate blocks or plates that move alternately relative to each other, advancing the waste over the grate. The grate blocks are kept mutually aligned in the plane of the grate by means of side plates located on either side of the grate, which can be pressed against the grate blocks by means of a grate block approach system. The approach system comprises a tie rod, the opposite ends of which are fitted with a stop disc resting on a support for the side plates. At one end of the approach system, the first stop disc is connected by a thread to a helical spring, which is in turn connected to the tie rod.At the other end, the tie rod is threaded and connected to the second thrust disc, through which it is inserted and held by a nut. The contact pressure between the thrust discs on the side plates, and therefore on the grid blocks, can be adjusted by tightening the nut appropriately.

[0008] US 4,018,168 discloses a furnace feed grate for an incinerator comprising transverse rows of grate blocks, the blocks in alternating rows being movable to feed waste along the grate. Clamping devices located on the underside of the grate elastically press the grate blocks of the respective rows together to prevent them from separating. A clamping shoe is located in the lower part of each of the two outermost blocks of a row and is provided with a spring-loaded barrel that is securely fixed to the clamping shoe. A clamping bar is held within the two spring barrels and is provided at both ends with stops for receiving the clamping pressure. The clamping bar and its two stops form a rigid unit, and the two clamping springs are elastically compressed between the stops on the bar each time.The axial displacement of the springs compensates for the expansion of the grate blocks due to heat when the incinerator is in operation. As an alternative to helical clamping springs, the use of cup springs is also mentioned.

[0009] Tension bars, in the form of solid metal bars attached to both ends of a row of grate blocks, have been known for decades as a means of keeping the grate blocks aligned in the combustion grate. A solid metal rod has generally been accepted as a solution that can withstand the heavy mechanical stresses present in an incinerator and meets the main technical requirements. For this reason, little effort has been made to optimize the role of this component, which is usually hidden in the combustion grate assembly.

[0010] However, improving the efficiency of incinerators in converting waste into energy is attracting increasing interest, which also depends on potential improvements in the air supply to the waste bed. Furthermore, simplifying incinerator maintenance remains a constant challenge. Moreover, the development of wider combustion grates is limited by the mechanical properties of the solid metal rods used to keep the grate blocks aligned. The longer the metal rod, the greater the expansion under temperature variations, which can cause the threads to loosen or the grate blocks to lift.

[0011] In summary, in the past, it was common to build smaller incinerators with a lower calorific value and therefore less thermal stress on the combustion grate. The resulting thermal expansion could be absorbed by a well-known steel rod acting as a tension bar. Due to the need to build increasingly larger incinerators and the resulting increasing thermal stress on the combustion grate, the steel rod is no longer satisfactory because failures are more likely.

[0012] It is necessary to further improve the combustion grates in which tension devices are designed to maintain the alignment of each row of grate blocks of the combustion grate so that the grate blocks fit closely together next to each other, in order to allow the development of wider combustion grates.

[0013] Accordingly, the object of the present invention is to provide a combustion grate equipped with an improved tensioning device to maintain the alignment of each row of grate blocks in the combustion grate, the tensioning device requiring little maintenance and having a simple and cost-effective construction. The present invention also aims to provide a combustion grate that can be wider than combustion grates currently available commercially.

[0014] This objective is achieved by the combustion grid defined in independent claim 1.

[0015] Preferred embodiments of the combustion grid according to the invention are described in the dependent claims.

[0016] An incinerator in a waste incineration plant may include one or more combustion grates arranged side by side. The combustion grate may be inclined downwards in the direction of the flow of a bed of waste to be burned.

[0017] The combustion grate comprises a first border zone and a second border zone opposite the first border zone, which laterally borders the grate combustion in a direction parallel to the direction of the combustion grate feed.

[0018] The combustion grate comprises rows of grate blocks aligned perpendicular to the direction of transport. Each row of grate blocks overlaps the preceding row to form the combustion grate. The grates in a row are attached to a fixed or movable guide located behind the grates, beneath the overlapping grates. The alternating rows of grate blocks can be moved in a reciprocating motion by a movable structure comprising the guide and providing the reciprocating motion.

[0019] A grid block comprises a block body which is generally configured as a molded part and which essentially has the shape of an elongated hollow parallelepiped with a longitudinal axis. The grid block comprises a top wall which forms a bearing face along which the incinerator load is to be transported, a front wall closing the grid block perpendicular to the longitudinal axis, and side walls closing the sides of the grid block.

[0020] The combustion grate includes a tensioning device for a row of grate blocks arranged within the combustion grate, designed to maintain the alignment of the row of grate blocks perpendicular to the direction of transport. The tensioning device extends along a longitudinal axis defining a longitudinal direction that is perpendicular or substantially perpendicular—that is, within the angular tolerance limits for maintaining the alignment of the row of grate blocks—to the direction of transport. The grate blocks are stably connected to one another by the tensioning device, which extends under the upper walls of the grate blocks, perpendicular to the direction of transport and across the inner width between the first and second edge zones.

[0021] According to the invention, the tensioning device comprises a cable having a first end zone and a second end zone opposite the first end zone, a first connection means for connecting the first end zone of the cable to a side wall of the first edge zone, and a second connection means for connecting the second end zone of the cable to a side wall of the second edge zone.

[0022] A cable as defined in the present invention consists of a group of metallic strands that are twisted or braided together to obtain a larger and stronger shape. Each strand may in turn be made up of several wires twisted together.

[0023] Various studies have shown that cables, particularly steel cables, have an ideal elasticity range to meet the requirements of a combustion grate in a large incinerator. Comparing their behavior under stress is best illustrated by the graph in [Fig. 8]. Cables have tensile strength and can withstand greater longitudinal stresses when stretched or pulled before breaking than a metal rod known in the prior art. Furthermore, unlike a metal rod which breaks suddenly, a cable is less critical in this respect, as its strands can easily take up the load again if other strands are damaged. It follows that the tensioning device is less sensitive to the various conditions present during incinerator operation, for example, less sensitive to expansion during operation or contraction during incinerator shutdown.

[0024] Furthermore, monitoring the wear of the tensioning device becomes easier because cable failures can be anticipated when certain strands are visibly damaged, which serves as a warning sign. In this case, the cable can be replaced before it breaks completely. On the other hand, monitoring the wear of a tension bar is more difficult to assess, and the risk of an entire row of grids lifting due to a tension bar failure is therefore more difficult to anticipate.

[0025] Furthermore, the cable can be dimensioned so that its modulus of elasticity allows for cable tension that maintains the alignment of the grid block row both when the block row is assembled and during incinerator operation. For this purpose, the tensioning device can be mounted, for example, by means of a cable tensioning clamp that pulls the cable to secure it to the side wall of the first border zone or, where applicable, the second border zone. This arrangement, without a separate tensioning means included in the tensioning device, is advantageous due to its simple and economical design.

[0026] In a preferred embodiment, the first and second edge zones are formed by pressure plates of the combustion grate extending parallel to the direction of transport. The lateral sides or side walls formed by the pressure plates also extend parallel to the direction of transport. In a row, the grate blocks are held stably aligned by a tensioning device extending perpendicular to the direction of transport and across the inner width between the pressure plates. The tension applied by the tensioning device presses against the pressure plates on both sides of the row of grate blocks. This embodiment enhances the stability of the combustion grate.

[0027] In another preferred embodiment, the first border zone and the second border zone are formed by a first lateral grid block and a second lateral grid block, respectively, the first lateral grid block forming a first end of the row and the second lateral grid block forming a second end of the row opposite the first end of the row. The first and second side grid blocks are positioned next to their corresponding side walls formed by the pressure plates. These blocks can be fixed to the pressure plates to create a robust structure. However, they can also be free to move relative to the pressure plates if the row of grid blocks is a movable row of the combustion grate. Within a row, the grid blocks are stably connected to each other by a tensioning device that extends perpendicularly to the direction of travel and across the inner width between the first and second side grid blocks.

[0028] In a preferred embodiment, one end of the first connection means that is opposite the cable and / or one end of the second connection means that is opposite the cable is formed as a base plate, the base plate being configured to be inserted into a similarly shaped hole in the side wall of the first border region and / or the side wall of the second border region, respectively, and then to be rotated by an angle, preferably of 90°, so as to rest on the surface of the side wall opposite the cable and to be retained in the mounted state of the grid block row.

[0029] In an embodiment where the first edge region is formed by the first side grid block, the end of the first connection means opposite the cable can be formed as a base plate that can be used as a locking means for the tensioning device on the first side grid block. The base plate consists of a plate having a geometry from which a shaft protrudes for a direct or indirect connection, i.e., via intermediate components, to the cable. To lock the tensioning device, the side wall of the first side grid block facing the cable has a hole similar in shape to that of the plate to allow the base plate to be inserted into the side wall.In the assembled state of the grid block row, the first connection point is positioned so that the base plate extends beyond the side wall inside the first lateral grid block. In this way, the plate can rest on the inward-facing side wall of the grid block, after the base plate has been rotated at an angle. This arrangement offers the advantage of easy assembly for installation and, conversely, easy disassembly for maintenance. Preferably, the base plate and the shaft are made of a single piece for increased strength.

[0030] Preferably, the base plate has a simple rectangular shape that is easy to manufacture. However, other shapes can be considered that allow the same locking principle, for example elliptical shapes.

[0031] On the opposite side of the tensioning device, the second connection means and the second lateral grid block can be formed in the same way as described above. This has the advantage of simplifying the mounting of the tensioning device. However, it is also possible for the opposite side of the tensioning device to be fixed by other means known in the art that do not include a base plate.

[0032] The same principle can be applied mutatis mutandis to the case where the first and second border regions are formed by pressure plates. To lock the tensioning device, the side wall formed by the pressure plate has a hole with a shape similar to that of the plate to allow the base plate to be inserted into the side wall.

[0033] In a preferred embodiment, the end of the first connecting means and that of the second connecting means are formed from a base plate. This embodiment can be assembled simply because the two ends are formed in the same way.

[0034] More generally, connection means configured to removably fix at least one of the first connection means or the second connection means to the first border region or the second border region, respectively, can be chosen to retain the tensioning device.

[0035] In a preferred embodiment, the first connection means or the second connection means is welded to the side wall of the first border zone or to the side wall of the second border zone, respectively. Welding advantageously simplifies assembly.

[0036] In a preferred embodiment, the first connection means and / or the second connection means comprise a cable connector configured to be connected in the assembled state to the first end region of the cable and / or the second end region of the cable, respectively. A cable connector constitutes an inexpensive interface between the cable and the first or second connection means, which can be permanently fixed to the first and / or second end of the cable using widespread and economical techniques. For example, the cable connector may comprise a longitudinally extending sleeve into which a cable end region is loosely inserted, and a mechanical or hydraulic tool compresses and deforms the sleeve, thereby creating a permanent seal between the cable and the cable connector.

[0037] In a preferred embodiment, the cable fitting includes a threaded section formed at the end of the cable fitting opposite the cable, and the first connection means and / or the second connection means includes a receiving threaded section corresponding to the threaded section for securing the cable fitting. This This arrangement allows for a simple connection interface between the cable and the first and / or second connection point in case the cable needs to be replaced. Preferably, the threaded receiving section is in the form of a rod with a longitudinal threaded hole.

[0038] In a preferred embodiment, the end of the first connection means and / or the second connection means facing the cable is formed as a base plate, wherein the base plate is formed as a plate having a geometry from which a shaft protrudes, an end region of the shaft facing the direction of the cable being configured as the cable fitting. The cable fitting may take the form of a blind hole extending longitudinally in the shaft and designed to receive the corresponding cable end region.

[0039] In a preferred embodiment, the cable fitting has two parallel surfaces diametrically opposed with respect to the longitudinal axis for torque transmission. Preferably, the two surfaces are equidistant from the longitudinal axis. The two surfaces are also preferably spaced far enough apart to allow tightening with a wrench of the appropriate size. The surfaces can also be used to hold the cable fitting in a fixed rotational position. This feature is useful when assembling and disassembling the tensioning device to hold the cable fitting in a fixed position or to apply torque.

[0040] In a preferred embodiment, the tensioning device includes a tensioning means for adjusting the cable tension in the mounted state of the grid block row. The tensioning means has the advantage that the tension range that can be applied to the tensioning device is wider than the tension range available based on the cable's modulus of elasticity alone. This can be advantageous if the temperature to which the tensioning device is subjected has a large range of variation, thus subjecting the tensioning device to significant expansion.

[0041] In a preferred embodiment, the tensioning means is a tensioner, which is a well-known means of applying tension in a tensioning device. In a preferred embodiment, the tensioner may be formed of a rod having a first threaded hole extending longitudinally from a first end of the rod, the threaded hole being configured to receive a threaded segment of the first or second connecting means. In addition, the rod has a second threaded hole extending longitudinally from a second end of the rod opposite the first end of the rod, the second threaded hole being configured to receive a threaded section formed at the end of the corresponding cable fitting, the thread of the second threaded hole extending in a direction opposite to the thread of the first threaded hole.

[0042] In a preferred embodiment, the first or second connection means comprises a main body separate from the cable connector and connected, in the mounted state, to the side wall of the first border zone or the side wall of the second border zone, respectively, and the tensioning means is disposed between the cable connector and the main body. Preferably, the tensioning means is configured to be connected at one end to the main body and at a second end opposite the first end to the cable connector. In this embodiment, the tensioning means is embedded within the first or second connection means between the main body and the cable connector, thus forming a compact arrangement.

[0043] It is also conceivable to place the tensioning means in an intermediate position along the cable, between two cable segments. Connections to the cable can be made using other cable fittings as described previously.

[0044] In a preferred embodiment, characterized in that at least one of the cable fittings has a threaded section formed at the end of the cable fitting opposite the cable, and in that the tensioning means is disposed between the cable fitting and the main body of the first or second connecting means, the threaded section of the cable fitting can be configured to be screwed directly into the tensioning means. This embodiment is also compact and requires fewer separate parts.

[0045] In another preferred embodiment, the tensioning means consists of a threaded portion formed in an end area of ​​the first connecting means facing the opposite side of the cable or in an end area of ​​the second connecting means facing the opposite side of the cable, wherein the threaded portion extends, in the mounted state, from the row of grid blocks through an opening in the side wall of the first edge region or an opening in the side wall of the second edge region, respectively, and the threaded portion is retained by at least one nut screwed onto each side of the side wall. Preferably, the threaded portion is disposed at the end of the first connecting means or the second connecting means facing the first edge region or the second edge region, respectively, so as to form a compact assembly.

[0046] In a preferred embodiment, the cable has a diameter of at least 6.0 mm, preferably between 8.0 mm and 25.0 mm, and preferably between 10.0 mm and 15.0 mm. These ranges cover the main temperature ranges that can be found in the incinerator while allowing sufficient tension on the grid block rows.

[0047] In a preferred embodiment, the cable is made of steel, preferably stainless steel to reduce the risk of corrosion and to withstand the range of temperatures present in the incinerator.

[0048] In a preferred embodiment, the cable has at least three strands to ensure a minimum modulus of elasticity.

[0049] In a preferred embodiment, the cable extends continuously from the first to the second end. In other words, the cable is not interrupted between the first and second ends. This embodiment avoids the use of connecting pieces that are necessary if the cable is supplied in several sections, thus reducing production costs.

[0050] The invention will be illustrated by means of the accompanying figures, in which:

[0051] Fig. 1 shows a perspective view of a combustion grid comprising a tensioning device according to the invention;

[0052] Fig. 2 shows a perspective view of a tensioning device according to the invention;

[0053] Fig. 3A shows a front view of part of the tensioning device according to Fig. 2 comprising a first connection means;

[0054] Fig. 3B shows a front view of the first connection means of Fig. 3A;

[0055] Fig. 3C shows a front view of the cable fitting of Fig. 3A;

[0056] Figure 4 shows a perspective view of the first means of connecting the [Fig.3B];

[0057] Fig. 5 shows a perspective view of the tensioner of Fig. 2;

[0058] Figure 6 shows a perspective view of part of the second means of connection of the [Fig.2];

[0059] Fig. 7A shows a front view of a cable according to another embodiment of the tensioning device;

[0060] Fig. 7B shows a front view of a first cable connection of Fig. 7A;

[0061] Figure 7C shows a front view of a second cable fitting arranged at the end of the cable in [Fig. 7A], opposite the first cable connection; and

[0062] Fig. 8 illustrates the behavior of a steel rod and two different steel cables under the effect of a tensile force.

[0063] The basic structure of a combustion grate 10 with its essential elements is illustrated in a perspective view in [Fig. 1]. In an incinerator of a waste incineration plant, several combustion grates 10 can be arranged side by side, as shown in [Fig. 1], where a portion of the combustion grates arranged laterally on either side of the combustion grate 10 is also illustrated.

[0064] The combustion grate 10 is inclined downwards in the direction of transport, as represented by an arrow 12. The combustion grate 10 is laterally delimited by a pair of side walls 14a, 14b formed by pressure plates 15a, 15b.

[0065] The combustion grate comprises rows 16 of grate blocks 18 aligned perpendicular to the direction of transport 12. Each row of grate blocks overlaps the preceding row to form the combustion grate. In [Fig. 1], the grate blocks are removed in the two rows at the rear of the combustion grate to show their attachment to a fixed or movable guide 20 at the rear of the grate blocks, which is located beneath the previously overlapping grate blocks. The alternating rows that move alternately are supported by a movable structure comprising the guide 20, said movable structure providing the alternating motion.

[0066] Each row of grid blocks comprises a first lateral grid block 22a forming a first end of the row and a second lateral grid block 22b forming a second end of the row opposite the first end of the row. The first grid block 22a and the second grid block 22b are adjacent to the corresponding lateral wall 14a, 14b and form respectively a first border zone and a second border zone.

[0067] In a row 16, the grid blocks 18 are stably connected to each other by a tensioning device. The tensioning device 30 extends perpendicularly to the transport direction 12 and across the inner width between the first lateral grid block 22a and the second lateral grid block 22b.

[0068] The tensioning device 30 comprises a first connection means 40 for connecting a first cable end zone 70a to a side wall of the first lateral grid block 22a, and a second connection means 50 for connecting a second cable end zone 70b to a side wall of the second lateral grid block 22b. In the embodiment shown, the side wall of the first lateral grid block facing the inside of the row and the side wall of the second lateral grid block facing the inside of the row each have an opening 54 through which the first and second connection means extend, respectively, for attachment to the side walls, for example, by nuts on the threaded ends of the first and second connection means. Other possible attachment methods for the first and second connection means are described below.

[0069] The tensioning device also includes a tensioning means in the form of a tensioner 60 disposed in the first connection means and configured to tension the tension bar in order to maintain the alignment of the grid blocks in a row.

[0070] The tensioning device 30 is shown in [Fig. 2]. The tensioning device 30 for a row of grid blocks arranged in a combustion grid is designed to maintain the alignment of the rows 16 of grid blocks 18.

[0071] The tensioning device 30 comprises a cable 70 having a first end zone 70a and a second end zone 70b opposite the first end zone, a first connection means 40 designed to connect the first end zone 70a to a side wall of the first grid block 22a, and a second connection means 50 designed to connect the second end zone 70b to a side wall of the second grid block 22b.

[0072] The cable 70 has a diameter of at least 12.0 mm, comprises at least three strands and is made of stainless steel.

[0073] The second connection means 50, also shown in [Fig. 4] and in the assembled state in [Fig. 3B], comprises a rectangular base plate 80 disposed at the end of the second connection means opposite the cable. A second cable fitting 82, in the form of a hollow cylindrical rod, protrudes longitudinally, perpendicular to the base plate, defining a blind hole extending longitudinally. The base plate 80 and the second cable fitting 82 are made in one piece. The base plate is configured to be inserted into a similarly shaped hole in the side wall of the second grid block 22b.The second connection means passes through the side wall so that it can subsequently be rotated by an angle, for example 90°, to rest on the surface of the side wall opposite cable 70 and secure the tensioning device in the mounted position of the grid block row. The blind hole is designed to receive the second end of cable 70b, which is secured in the blind hole preferably by shrinking.

[0074] As shown in [Fig. 3A], a first cable fitting 86 is located at the first end of the cable 70a. It is in the form of a hollow cylindrical rod extending longitudinally and forming a blind hole in the direction of the cable. The blind hole is designed to receive the first end zone of the cable. The cable fitting extends longitudinally in the opposite direction to the cable in the form of an external threaded rod 88, as shown in [Fig. 3C]. The first connection means has two parallel surfaces 90, only one of which is visible in [Fig. 3C], formed on the first cable fitting 86 and designed for the transmission of torque by positive locking.

[0075] The tensioner 60 used as a tensioning means to adjust the cable tension is formed of a rod having a hexagonal cross-section, as illustrated in [Fig. 5], to allow tightening with a wrench. The rod has a first threaded hole extending longitudinally from a first end of the rod 60a, the threaded hole being configured to receive a threaded segment 100 of the first connecting means 40.

[0076] The rod has a second threaded hole extending longitudinally from a second end of the rod 60b opposite the first end of the rod. The second threaded hole is configured to receive the threaded rod externally from the first connecting means 40, the thread of the second threaded hole extending in a direction opposite to the thread of the first threaded hole. A marking 62 is present at the second end of the rod to identify the orientation of the tensioner and the corresponding thread directions in the assembled state of the tensioning device.

[0077] The first connection means further comprises a rectangular base plate 102 disposed at the end of the first connection means opposite the cable. A cylindrical shaft 104 projects longitudinally perpendicularly from the base plate. The base plate 102 is configured to be inserted into a similarly shaped hole in the side wall of the first grid block 22a. The first connection means extends through the side wall so that it can be subsequently rotated by an angle, for example 90°, to rest on the surface of the side wall opposite the cable 70 and secure the tensioning device in the mounted position of the grid block row. The shaft 104 terminates in the threaded segment 100 configured to be screwed into the first threaded hole of the tensioner 60.

[0078] Another embodiment illustrated in Figures 7A to 7C is also conceivable in which a first cable fitting 86 is disposed at the first end zone of the cable 70a, the cable fitting having the same embodiment as the first cable fitting described above and being designed to receive the first end zone of the cable. The first cable fitting extends longitudinally in the direction opposite to the cable in the form of an external threaded rod 88, as shown in [Fig. 7C]. A second cable fitting 86', of the same shape as the first cable fitting 86, is disposed in the second end zone of the cable 70b.

[0079] The graph in [Fig. 8] shows the elongation of a steel rod (reference A) and two different steel cables (reference B, reference C) measured along the X-axis (from 0 mm to 200 mm) under the effect of a tensile force represented along the Y-axis (from 0 N to 90,000 N). Reference A is a known steel rod used in the combustion grate to keep the grate blocks aligned. Reference B is a 19-strand cable made of A4 1.4401 AISI 316 stainless steel, with a stiffness of 1260–1570 N / mm. Reference C is a 7x7-strand cable made of A4 1.4401 AISI 316 stainless steel, with a stiffness of 1570 N / mm. The thermal expansion of the combustion grate in all directions, particularly along the rows of grate blocks, is the source of the tensile force acting on the steel rod or steel cables.

[0080] For the same initial length of 2.75 m and a diameter of 10 mm, the steel rod (reference A) only breaks after an elongation of about 10 mm, whereas the steel cables resist an elongation of 120 mm to 180 mm for the reference B and reference C cables, respectively. List of reference signs

[0081] Combustion grid 10

[0082] transport direction 12

[0083] side walls of the combustion grate 14a, 14b

[0084] pressure plates 15a, 15b

[0085] rows of grid blocks 16

[0086] grid blocks 18

[0087] Grid block guide 20

[0088] first and second lateral grid block 22a, 22b

[0089] voltage device 30

[0090] first means of connection 40

[0091] second means of connection 50

[0092] opening in the side wall of the grid block 54

[0093] tensioner 60

[0094] first and second ends of the rod 60a, 60b

[0095] marking 62

[0096] cable 70

[0097] first and second ends of cable 70a, 70b

[0098] base plate of the second connection means 80

[0099] second cable connection 82

[0100] first cable connection 86

[0101] external threaded rod 8 8

[0102] surfaces for the transmission of torque 90

[0103] threaded segment 100

[0104] base plate of the first connection means 102

[0105] tree of the first means of connection 104

Claims

Demands

1. Combustion grate (10) for an incinerator in a waste incineration plant, the combustion grate (10) having a first border zone and a second border zone opposite the first border zone, this first border zone and this second border zone laterally bordering the combustion grate (10) and extending in a direction parallel to a transport direction (12) of the combustion grate, a row of grate blocks extending between the first border region and the second border region, the combustion grate comprising a tensioning device (30) for the row (16) of grate blocks (18) arranged in the combustion grate (10), the tensioning device (30) extending in a longitudinal direction and being designed to maintain the alignment of the row of grate blocks,characterized in that the tensioning device comprises a cable (70) having a first end zone (70a) and a second end zone (70b) opposite the first end zone (70a), a first connection means (40) for connecting the first end zone of the cable (70a) to a side wall (14a) of the first edge zone, and a second connection means (50) for connecting the second end zone of the cable (70b) to a side wall (14b) of the second edge zone.

2. Combustion grid (10) according to claim 1, characterized in that the first edge region and the second edge region are formed by pressure plates (15a, 15b) of the combustion grid which extend parallel to the direction of transport (12), or in that the first edge region and the second edge region are formed by a first lateral grid block (20a) and a second lateral grid block (20b), respectively, the first lateral grid block (20a) forming a first end of the row and the second lateral grid block (20b) forming a second end of the row opposite the first end of the row.

3. Combustion grid (10) according to claim 1 or 2, characterized in that one end of the first connection means (40) oriented opposite to the cable and / or one end of the second connection means (50) oriented opposite to the cable is formed as a base plate, the base plate is configured to be inserted into a similarly shaped hole in the side wall of the first border zone and / or the side wall of the second border zone, respectively, and then to be rotated at an angle, preferably 90°, so as to rest on the surface of the side wall opposite to the cable (70) and to be retained in a mounted state of the row (16) of grid blocks (18).

4. Combustion grid (10) according to any one of claims 1 or 2, characterized in that the first connecting means (40) or the second connecting means (50) is welded to the side wall of the first border zone or to the side wall of the second border zone, respectively.

5. Combustion grid (10) according to any one of claims 1 to 4, characterized in that the first connection means (40) and / or the second connection means (50) comprise a cable fitting (82, 86) configured to be connected in the mounted state with the first cable end zone (70a) and / or the second cable end zone (70b), respectively.

6. Combustion grid (10) according to claim 5, characterized in that the cable fitting (82, 86) comprises a threaded section formed at the end of the cable fitting opposite the cable, and in that the first connection means (40) and / or the second connection means (50) comprises a receiving threaded section corresponding to the threaded section for fixing the cable fitting (82, 86), the receiving threaded section preferably being in the form of a rod having a threaded longitudinal hole.

7. Combustion grid (10) according to any one of claims 5 to 6, characterized in that the cable fitting (82, 86) has two parallel surfaces (90) diametrically opposed with respect to a longitudinal axis of the tensioning means for the transmission of torque.

8. Combustion grate (10) according to any one of claims 1 to 7, characterized by a tensioning device for adjusting the tension of the cable (70) in the mounted state of the row of grid blocks (18).

9. Combustion grid (10) according to claim 8, characterized in that the tensioning means is a tensioner (60).

10. Combustion grid (10) according to any one of claims 5 to 7 and any one of claims 8 to 9, characterized in that the first connection means or the second connection means comprises a main body separate from the cable fitting and connected in the mounted state to the side wall (14a) of the first border zone or to the side wall (14b) of the second border zone, respectively, and in that the tensioning means is disposed between the cable fitting and the main body.

11. Combustion grid (10) according to claim 8, characterized in that the tensioning means is formed as a threaded part formed in an end area of ​​the first connecting means (40) facing the opposite of the cable (70) or in an end area of ​​the second connecting means (50) facing the opposite of the cable (70), the threaded part extends in the mounted state from the row of grid blocks (18) through an opening in the side wall (14a) of the first border area or an opening in the side wall (14b) of the second border area, respectively, and the threaded part is retained by at least one nut on each side of the side wall.

12. Combustion grid (10) according to any one of claims 1 to 11, characterized in that the cable (70) has a diameter of at least 6.0 mm, preferably between 8.0 mm and 25.0 mm, preferably further between 10.0 mm and 15.0 mm.

13. Combustion grid (10) according to any one of claims 1 to 12, characterized in that the cable (70) is made of stainless steel.

14. Combustion grid (10) according to any one of claims 1 to 13, characterized in that the cable (70) has at least three strands.

15. Combustion grid (10) according to any one of claims 1 to 14, characterized in that the cable (70) extends continuously from the first end zone of the cable (70a) to the second end zone of the cable (70b).

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