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 of a waste incineration plant

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

[0002] The combustion grate provides the necessary support for the waste as it is transported through the combustion sequence. Typically, the combustion grate may be of the forward-moving reciprocating type, with grate blocks each inclined at an angle and with 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 row preceding it to form the combustion grate. The alternating rows that move back and forth are supported by a movable structure that provides the reciprocating movement. 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 comprised of rows of grate blocks and include pressure plates defining the lateral sides of the combustion grate, the pressure plates being disposed on either side of the rows.

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

[0005] The tension bar is essentially a solid metal bar with a turnbuckle at the other end. Preferably, the tension bar is located approximately midway 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 in a cold state. During operation, the tension bar is cooled by combustion air flowing under the combustion grate, while the combustion grate is subjected to temperatures relative to the fire above. Therefore, the tension bars can still reach temperatures of up to 400°C or more.As a result, tension bars are very sensitive to various conditions present during operation, for example expanding during operation or contracting during furnace shutdown. Defining the appropriate tension for mounting tension bars remains a difficult task, particularly because the failure of one tension bar would cause the entire row of grate blocks to lift and require a shutdown to repair it.

[0006] Document US5377663A 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 composed of two sections. A first section includes a leading end inserted through a hole in one side of a side grid block of a row of grid blocks and an end opposite the leading end. The opposite end has a threaded portion that engages a tensioner. A second section includes another leading end inserted through a hole in one side of another side grid block disposed at the opposite end of the row of grid blocks and an end opposite the other leading end, the opposite end also having a threaded portion that engages the tensioner. When mounted, the tensioner is rotated to increase or decrease the tension on the tension bar.Each section of the tension bar further includes a middle section that is replaced by a spring section to better accommodate the tensions in the tension bar and the varying conditions in plant operations that can slowly or abruptly change the tension on the tension bar. The tension bar includes 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 can also react differently to corrosion, which can lead to additional maintenance work.

[0007] WO 2011 / 063912A1 discloses a waste disposal plant in which waste deposited on a combustion grate is burned, said combustion grate comprising at least one handling group formed by several grate blocks or plates which move alternately relative to each other, advancing the waste on 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 provided with a stop disc resting on a support of the side plates. At a first 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 stop disc through which it is inserted and held by a nut. The contact pressure between the stop discs on the side plates and thus on the grid blocks can be adjusted by screwing the nut appropriately.

[0008] US 4,018,168 discloses a furnace feed grate of an incinerator comprising transverse rows of grate blocks, the blocks of the alternating rows being movable to feed the waste along the grate. Clamping devices located on the underside of the grate elastically press the grate blocks of the respective rows to prevent them from moving apart from each other. A clamping shoe is placed in the lower part of each of the two outer blocks of a row and is provided with a spring barrel which is firmly fixed on the clamping shoe. A clamping bar is held in the two spring barrels and is provided at its two 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 each elastically compressed between the stops of the bar.The axial displacement of the springs allows to compensate for the expansion of the grate blocks due to heat when the incinerator is in operation. As an alternative to helically wound clamping springs, the use of cup springs is also mentioned.

[0009] Tension rods, 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 been generally accepted as a solution that withstands 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 usually hidden component in the assembly of a combustion grate.

[0010] However, there is growing interest in improving the efficiency of incinerators in converting waste to energy, which also depends on potential improvements in the air supply to the waste bed. In addition, there is still a need to simplify the maintenance of incinerators. Furthermore, the development of wider combustion grates is limited by the mechanical characteristics of the solid metal rods used to keep the grate blocks aligned. The longer the metal rod, the greater the expansion under temperature variations, so that the threads become loose or the grate blocks lift off.

[0011] In summary, in the past it was common to build smaller incinerators with 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 ever larger incinerators and the resulting increasing thermal stress on the combustion grate, the steel rod is no longer satisfactory as failures are more likely.

[0012] There is a need for further improvement in combustion grates in which tensioning devices are provided to maintain the alignment of each row of grate blocks of the combustion grate so that the grate blocks fit closely together, to enable the development of wider combustion grates.

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

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

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

[0016] An incinerator of a waste incineration plant may comprise a combustion grate or several combustion grates arranged next to each other. The combustion grate may be inclined downwards in the direction of conveyance 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 flow of the combustion grate.

[0018] The combustion grate comprises rows of grate blocks aligned perpendicular to the direction of transport. Each row of grate blocks overlaps the row preceding it to form the combustion grate. The grates in a row are attached to a fixed or movable guide located at the rear of the grates, below 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 grate block comprises a block body which is generally configured as a casting and which has essentially the shape of an elongated hollow parallelepiped with a longitudinal axis. The grate block comprises a top wall which forms a bearing face along which the incinerator load is to be transported, a front wall closing the grate block perpendicular to the longitudinal axis and side walls closing the sides of the grate block.

[0020] The combustion grate comprises a tensioning device for a row of grate blocks arranged in the combustion grate, configured 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 which is perpendicular or substantially perpendicular, i.e. 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 each other 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 areas.

[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 within the meaning of the present invention consists of a group of metal strands which are twisted or braided together to obtain a larger and stronger shape. Each strand may in turn consist 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. Comparison of the behaviors under stress is better illustrated by the graph in [Fig. 8]. Cables have a 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 at once, a cable is less critical in this respect, because the strands of which it is composed can easily take up the load in case other strands are damaged. It follows that the tensioning device is less sensitive to the various conditions present during operation of the incinerator, for example less sensitive to expansion during operation or retraction during shutdown of the incinerator.

[0024] Furthermore, monitoring the wear of the tensioning device becomes easier because cable failures can be anticipated when some strands are visibly damaged, which constitutes an alarm signal. 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 estimate and the risk of seeing an entire row of grids lift due to the breakage of the tension bar is consequently more difficult to anticipate.

[0025] Furthermore, the cable may be dimensioned such that its modulus of elasticity allows a tension of the cable which maintains the alignment of the row of grate blocks in the assembled state of the row of blocks and during operation of the incinerator. For this purpose, the tensioning device may be mounted, for example, by means of a cable tensioning clamp for pulling the cable to fix it to the side wall of the first border zone or, if applicable, the second border zone. This arrangement without separate tensioning means included in the tensioning device is advantageous for its simple and economical design.

[0026] In a preferred embodiment, the first edge region and the second edge region are formed by pressure plates of the combustion grate which extend parallel to the direction of transport. The lateral sides or side walls formed by the pressure plates extend parallel to the direction of transport. In a row, the grate blocks are kept stably aligned by the tensioning device which extends perpendicular to the direction of transport and over the inner width between the pressure plates. The tension applied by the tensioning device presses the pressure plates on both sides of the row of grate blocks. This embodiment increases the stability of the combustion grate.

[0027] In another preferred embodiment, the first border area and the second border area are formed by a first side grid block and a second side grid block, respectively, the first side grid block forming a first end of the row and the second side grid block forming a second end of the row opposite the first end of the row. first side grate block and the second side grate block are arranged next to the corresponding side walls formed by the pressure plates. The first side grate block and the second side grate block can be fixed to the pressure plates to form a robust structure. However, the first side grate block and the second side grate block can also be free to move relative to the pressure plates if the row of grate blocks is a movable row of the combustion grate. In a row, the grate blocks are stably connected to each other by the tensioning device which extends perpendicular to the direction of transport and across the inner width between the first side grate block and the second side grate block.

[0028] In a preferred embodiment, one end of the first connecting means that is opposite the cable and / or one end of the second connecting 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 edge region and / or the side wall of the second edge region, respectively, and to then be rotated through an angle, preferably 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 row of grid blocks.

[0029] In an embodiment where the first edge region is formed by the first side grill block, the end of the first connection means opposite the cable may be formed as a base plate which may be used as a means for locking the tensioning device to the first side grill block. The base plate consists of a plate having a geometry from which a shaft protrudes for direct or indirect connection, i.e. via intermediate components, to the cable. To lock the tensioning device, the side wall of the first side grill block facing the cable has a hole of similar shape to that of the plate to allow insertion of the base plate into the side wall.In the assembled state of the row of grid blocks, the first connecting means is positioned such that the base plate projects beyond the side wall inside the first side grid block. In this way, the plate can rest on the inwardly facing side wall surface of the grid block, after the base plate has been turned through an angle. This arrangement has the advantage of easy assembly for installation and, conversely, disassembly for maintenance. Preferably, the base plate and the shaft are made of a single piece for improved strength.

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

[0031] On the opposite side of the tensioning device, the second connecting means and the second side grid block may be formed in the same manner 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 secured by other means known in the art which do not include a base plate.

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

[0033] In a preferred embodiment, the end of the first connecting means and that of the second connecting means are made of 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 secure at least one of the first connection means or the second connection means to the first edge region or the second edge region, respectively, may be selected to retain the tensioning device.

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

[0036] In a preferred embodiment, the first connecting means and / or the second connecting means comprise a cable fitting configured to be connected in the mounted state with the first end region of the cable and / or the second end region of the cable, respectively. A cable fitting provides an inexpensive interface between the cable and the first or second connecting means, which can be permanently attached to the first and / or second end of the cable using widespread and economical techniques. For example, the cable fitting may comprise a longitudinally extending sleeve into which an end region of the cable 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 fitting.

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

[0038] In a preferred embodiment, the end of the first connection means and / or the second connection means that faces 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 adapted to receive the corresponding cable end region.

[0039] In a preferred embodiment, the cable connection has two parallel surfaces diametrically opposed to the longitudinal axis for transmitting torque. Preferably, the two surfaces are at the same radial distance from the longitudinal axis. The two surfaces are preferably at a distance from each other that allows them to be tightened using a wrench of the corresponding size. The surfaces can also be used to hold the cable connection in a fixed rotational position. This feature is useful when mounting and dismounting the tensioning device to hold the cable connection in a fixed position or to apply torque.

[0040] In a preferred embodiment, the tensioning device comprises tensioning means for adjusting the tension of the cable in the mounted state of the row of grid blocks. 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 elastic modulus of the cable alone. This can be advantageous if the temperature to which the tensioning device is subjected has a large variation range, thus subjecting the tensioning device to a large expansion.

[0041] In a preferred embodiment, the tensioning means is a turnbuckle which is a well-known means of applying tension in a tensioning device. In a preferred embodiment, the turnbuckle may be formed from 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 connecting means or the second connecting means. Further, 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 the thread of the first threaded hole.

[0042] In a preferred embodiment, the first connection means or the 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 area or to the side wall of the second border area, respectively, and the tensioning means is arranged between the cable connector and the main body. Preferably, the tensioning means is configured to be connected at a first 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 in the first connection means or in the 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 of the cable between two segments of the cable. Connections to the cable can be provided by other cable fittings as described above.

[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 connecting means or the second connecting means, the threaded section of the cable fitting may 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 region of the first connecting means that faces away from the cable or in an end region of the second connecting means that faces away from the cable, wherein the threaded portion extends in the mounted state of 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 on each side of the side wall. Preferably, the threaded portion is arranged at the end of the first connecting means or the second connecting means facing the first edge region or the second edge region, respectively, in order 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, 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 of the rows of grate blocks.

[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 comprises 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 of the cable. In other words, the cable is not interrupted between the first and second ends of the cable. This embodiment avoids the use of connecting pieces which are necessary if the cable is supplied in several sections, thus reducing production costs.

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

[0051] [Fig. 1] shows a perspective view of a combustion grate 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 a 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 connector of [Fig.3A];

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

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

[0058] [Fig.6] shows a perspective view of a part of the second means of connection of [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 connector of [Fig.7A];

[0061] [Fig.7C] shows a front view of a second cable connector disposed at the end of the cable of [Fig.7A], opposite the first cable fitting; 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.l]. In an incinerator of a waste incineration plant, several combustion grates 10 may be arranged next to each other, as shown in [Fig.l], where a part 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 shown 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 conveying direction 12. Each row of grate blocks overlaps the row preceding it to form the combustion grate. In [Fig.l], the grate blocks are removed in the two rows at the rear of the combustion grate to show attachment to a fixed or movable guide 20 at the rear of the grate blocks which is located under the previously overlapping grate blocks. The alternating rows which move in an alternative manner are supported by a movable structure comprising the guide 20, said movable structure providing the reciprocating movement.

[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 side wall 14a, 14b and respectively form 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 perpendicular to the transport direction 12 and across the inner width between the first side grid block 22a and the second side grid block 22b.

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

[0069] The tensioning device also comprises a tensioning means in the form of a tensioner 60 disposed in the first connecting means and configured to tension the tension bar to maintain 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 grate blocks arranged in a combustion grate is designed to maintain the alignment of the rows 16 of grate 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 configured to connect the first end zone 70a to a side wall of the first grid block 22a, and a second connection means 50 configured 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 connecting means 50, also shown in [Fig. 4] and in the assembled state in [Fig. 3B], comprises a rectangular-shaped base plate 80 disposed at the end of the second connecting means opposite the cable. A second cable connector 82, in the form of a hollow cylindrical rod, projects in the longitudinal direction, perpendicular to the base plate, defining a longitudinally extending blind hole. The base plate 80 and the second cable connector 82 are manufactured in a single 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 connecting means passes through the side wall so that the second connecting means can be subsequently rotated through an angle, for example 90°, to rest on the surface of the side wall opposite the cable 70 and fix the tensioning device in the mounted state of the row of grid blocks. The blind hole is adapted to receive the second end of the cable 70b which is fixed in the blind hole preferably by shrinking.

[0074] As shown in [Fig. 3A], a first cable connector 86 is disposed 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 adapted to receive the first end region of the cable. The cable connector extends longitudinally in the direction away from the cable in the form of an externally threaded rod 88, as shown in [Fig. 3C]. The first connecting means comprises two parallel surfaces 90, only one of which is visible in [Fig. 3C], formed on the first cable connector 86 and adapted for transmission of torque by positive locking.

[0075] The turnbuckle 60 used as a tensioning means for adjusting the tension of the cable is formed of a rod having a hexagonal cross-section, as illustrated in [Fig.5], to allow tightening using 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 being configured to receive the externally threaded rod of 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 mounted state of the tensioning device.

[0077] The first connecting means further comprises a rectangular-shaped base plate 102 disposed at the end of the first connecting means opposite the cable. A cylindrical shaft 104 projects in the longitudinal direction perpendicular to 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 connecting means extends through the side wall so that the first connecting means can be subsequently rotated through an angle, for example 90°, to rest on the surface of the side wall opposite the cable 70 and fix the tensioning device in the mounted state of the row of grid blocks. 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 connector 86 is arranged at the first cable end region 70a, the cable connector having the same embodiment as the first cable connector described above and being adapted to receive the first cable end region. The first cable connector extends longitudinally in the direction away from the cable in the form of an external threaded rod 88, as shown in [Fig.7C]. A second cable connector 86', of the same shape as the first cable connector 86, is arranged in the second cable end region 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 on the X axis (from 0 mm to 200 mm) under the effect of a tensile force represented on the Y axis (from 0 N to 90000 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, stiffness of 1570 N / mm. Thermal expansion of the combustion grate in all directions, especially 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 rupture of the steel rod (reference A) only occurs after an elongation of approximately 10 mm, whereas the steel cables resist up to an elongation of 120 mm to 180 mm for the reference B and reference C cables, respectively. List of reference signs

[0081] Combustion grate 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 side grid block 22a, 22b

[0089] tension device 30

[0090] first connection means 40

[0091] second connection means 50

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

[0093] tensioner 60

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

[0095] marking 62

[0096] cable 70

[0097] first and second end of the 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] shaft of the first connection means 104

Claims

Claims

1. A combustion grate (10) for an incinerator of a waste incineration plant, the combustion grate (10) having a first border region and a second border region opposite the first border region, said first border region and second border region laterally bordering the combustion grate (10) and extending in a direction parallel to a conveying 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 adapted to maintain 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 border 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 border zone.,

2. A combustion grate (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 grate which extend parallel to the conveying direction (12), or in that the first edge region and the second edge region are formed by a first side grate block (20a) and a second side grate block (20b), respectively, the first side grate block (20a) forming a first end of the row and the second side grate block (20b) forming a second end of the row opposite the first end of the row.

3. Combustion grate (10) according to claim 1 or 2, characterized in that one end of the first connecting means (40) facing away from the cable and / or one end of the second connecting means (50) facing away from 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 area and / or the side wall of the second border area, respectively, and to then be rotated through an angle, preferably 90°, so as to rest on the surface of the side wall facing away from the cable (70) and to be retained in a mounted state of the row (16) of grate blocks (18).

4. Combustion grate (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 area or to the side wall of the second border area, respectively.

5. Combustion grate (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 connector (82, 86) configured to be connected in the mounted state with the first cable end area (70a) and / or the second cable end area (70b), respectively.

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

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

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

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

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

11. Combustion grate (10) according to claim 8, characterized in that the tensioning means is formed as a threaded portion formed in an end area of the first connecting means (40) which faces away from the cable (70) or in an end area of the second connecting means (50) which faces away from the cable (70), the threaded portion extends in the mounted state of the row of grate 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 portion is retained by at least one nut on each side of the side wall.

12. Combustion grate (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, more preferably between 10.0 mm and 15.0 mm.

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

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

15. Combustion grate (10) according to 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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