Patent Application
20190301734
The present invention relates to a movable grate for a furnace including a number of grate lanes arranged side by side between a left side section and a right side section, neighbouring grate lanes being connected by means of a midsection, each grate lane including at least one lane section having a number of pivotal grate shafts carrying grate bars and thereby defining an inclined grate surface of said lane section, each midsection including an upper relatively narrow housing section arranged between grate bars of the corresponding neighbouring grate lanes and a lower relatively broad housing section protruding at least partly under grate bars of said corresponding neighbouring grate lanes, each grate shaft having a driven grate shaft end and a non-driven grate shaft end, each grate shaft end being journalled in a respective bearing, the left and right side sections enclosing bearings for corresponding grate shaft ends of the left and right outermost grate lanes, respectively, and the upper relatively narrow housing section of each midsection enclosing bearings for corresponding grate shaft ends of corresponding neighbouring grate lanes, each lane section being provided with a drive mechanism including an actuator for pivoting back and forth neighbouring grate shafts in opposite rotational directions so as to impart a wave-like movement to material on the grate surface in order to transport such material downwards, a synchronising mechanism being arranged to maintain a predetermined clearance between edge portions of grate bars of neighbouring grate shafts.
GB 1 255 555 A discloses a movable grate, for a furnace or an incinerator, in the form of steps, wherein each step is rockable by a drive mechanism to impart a wave-like motion to the material on the grate. Synchronizing means between juxtaposed steps maintains a predetermined clearance between the adjoining edge portions of those steps. The grate is divided into an upper and lower section, there being a drive mechanism for each section and each section has a different rate of movement.
WO 89/04441 discloses a movable grate comprising a number of grate steps which are arranged adjacent each other, partly overlap one another and are pivotal about an axis extending in the longitudinal direction of said grate step, and which are pivotally mounted outside shield members which in lateral direction enclose a combustion chamber. End plates are rigidly secured to the ends of the grate steps and pivotal therewith; the end plates being aligned with and fitted in openings in the shield members. Portions of the shield members having openings aligned with the end plates are displaceably mounted relative to adjoining shield members in the direction of the grate step axis, and the shield portions which radially outwardly sealingly engage adjoining shield members and radially inwardly sealingly engage the end plates, are in the direction of said axis held in a fixed position in relation to the grate step shaft.
WO 99/63270 discloses a grate device for a combustion furnace comprising a grate element and a turnable shaft assembly connected thereto. The grate element has a first system of ducts for circulating coolant through the grate element. The shaft assembly has a second system of ducts, which communicates with the first system of ducts and forms a coolant inlet and outlet. The grate element comprises a girder means which is non-rotatably connected with the shaft assembly and which contains a part of the first system of ducts, which part communicates with the second system of ducts. The grate element comprises a plate means which is mounted on the girder means and forms a grate area and through which the remaining part of the first system of ducts extends for cooling the grate area.
In these known devices, the grate bars on each grate shaft coincide with the grate bars on the neighbouring shaft without touching these, thereby forming a cohesive grate surface. The gap between two coinciding grate bars may for instance be approximately 1 to 3 millimetres.
The grate function is such that the grate shafts alternately turn to their respective outer positions, and the grate surface thus forms a stair-shaped surface where the steps change direction. This produces a rolling movement to material present on the grate, which may have the effect of breaking it up and agitating it, while at the same time moving it forward in downward direction, thus achieving good exposure to radiant heat from a combustion chamber and good exposure to combustion air.
In addition to the above-mentioned grate devices, devices are known, wherein two grates of the above described type are arranged side by side and so that the grate device is composed by two grate lanes connected by means of a midsection. Thereby, the two grate lanes are arranged symmetrically so that the drive mechanisms are arranged along the outer free sides of the arrangement in order to provide for a slim midsection between the two grate lanes and in order to ensure easy access in connection with service and maintenance. In this way, a larger grate width and better flexibility may be obtained. The latter may be achieved due to the possibility of operating each grate lane independently, whereby the individual speeds of the grate lanes may be adapted to the amount of material present of the individual grate lanes. However, in these devices it is of importance that the midsection is relatively slim, because the midsection does not provide any movement to material present thereon, and no exposure to heat or combustion air is provided thereby. Furthermore, it is of importance that the drive mechanisms are not freely exposed under the grate lanes in order to reduce maintenance and in order to provide access to the drive mechanisms even during operation of the furnace, in the case that maintenance is necessary.
In order to achieve even larger grate widths and good flexibility, it would be desirable to combine even more than two grate lanes into one unit.
The object of the present invention is to provide a type of movable grate suitable for the arrangement of more than two grate lanes side by side close to each other while still providing good accessibility in connection with service and maintenance.
In view of this object, at least one midsection includes the drive mechanism and the synchronising mechanism of at least one lane section, and the actuator of said drive mechanism and said synchronising mechanism are located in the lower relatively broad housing section of said at least one midsection.
Thereby, by locating the actuator of said drive mechanism and said synchronising mechanism in the lower relatively broad housing section of said at least one midsection, it is possible to incorporate a drive mechanism in the midsection while maintaining a relatively narrow upper midsection and also providing good access to drive mechanism and synchronising mechanism during service and maintenance.
In an embodiment, in the at least one midsection including the drive mechanism and the synchronising mechanism of the at least one lane section, the mutual relative pivotal positions of the respective grate shafts of the at least one lane section are individually adjustable by means of respective clearance adjustment mechanisms located in the lower relatively broad housing section of said at least one midsection. Thereby, by locating the respective clearance adjustment mechanisms in the lower relatively broad housing section, the clearance adjustment mechanisms may be easily accessible, thereby facilitating service and maintenance.
In an embodiment, in the at least one midsection including the drive mechanism and the synchronising mechanism of the at least one lane section, the mutual relative pivotal positions of the respective grate shafts of the at least one lane section are individually elastically biased towards respective predetermined relative pivotal positions by means of respective biasing mechanisms located in the lower relatively broad housing section of said at least one midsection. Thereby, if the movement of a grate shaft is prevented, the movement may wholly or partly be taken up by the biasing mechanisms. Furthermore, by locating the respective biasing mechanisms in the lower relatively broad housing section, the biasing mechanisms may be easily accessible, thereby facilitating service and maintenance.
In an embodiment, in the at least one midsection including the drive mechanism and the synchronising mechanism of the at least one lane section, a number of drive shafts corresponding to the respective grate shafts of the at least one lane section are located in the lower relatively broad housing section of said at least one midsection, and the driven grate shaft end of each said grate shaft is individually in driven connection with a corresponding one of said drive shafts. Thereby, by driving each grate shaft independently by means of a respective drive shaft located in the lower relatively broad housing section of the midsection, the movement of each grate shaft may be controlled independently from an easily accessible location, thereby facilitating precise control and adjustment of the movement of each separate grate shaft in connection with service and maintenance.
In a structurally particularly advantageous embodiment, the driven grate shaft end of the respective grate shafts of the at least one lane section is provided with a respective grate shaft lever arm, a first end of the grate shaft lever arm is in driving connection with the grate shaft and a second end of the grate shaft lever arm is pivotally connected to a first end of a corresponding connection rod extending down into the lower relatively broad housing section of said at least one midsection, and a second end of said connection rod located in said relatively broad housing section is in driven connection with the actuator of said drive mechanism. Thereby, by driving each grate shaft by means of a connection rod, a precise transmission of the movement from the actuator to the grate shaft is possible. Furthermore, by driving each grate shaft independently by means of a respective connection rod extending down into the lower relatively broad housing section of the midsection, the movement of each grate shaft may be controlled independently from an easily accessible location, thereby facilitating precise control and adjustment of the movement of each separate grate shaft in connection with service and maintenance.
In an embodiment, the driven connection between the second end of said respective connection rods and the actuator of said drive mechanism is individually adjustable in order to adjust the individual predetermined clearance between edge portions of grate bars of neighbouring grate shafts. Thereby, the adjustment of the driven connection may be performed in the lower relatively broad housing section, thereby facilitating adjustment of clearance in connection with service and maintenance.
In an embodiment, the driven grate shaft end of each said grate shaft is provided with a grate shaft lever arm, a first end of the grate shaft lever arm is in driving connection with the grate shaft and a second end of the grate shaft lever arm is pivotally connected to a first end of a corresponding connection rod, each said drive shaft is provided with a drive shaft lever arm, and a first end of the drive shaft lever arm is in driven connection with the drive shaft and a second end of the drive shaft lever arm is pivotally connected to a second end of a corresponding connection rod so that each grate shaft lever arm is connected with a corresponding drive shaft lever arm by means of a corresponding connection rod. Thereby, by driving each grate shaft by means of a connection rod, a precise transmission of the movement from the actuator to the grate shaft is possible. Furthermore, by driving each grate shaft independently by means of a respective connection rod extending down into the lower relatively broad housing section of the midsection, the movement of each grate shaft may be controlled independently from an easily accessible location, thereby facilitating precise control and adjustment of the movement of each separate grate shaft in connection with service and maintenance.
In an embodiment, each connection rod is pivotally connected to the corresponding grate shaft lever arm by means of a first ball joint, and each connection rod is pivotally connected to the corresponding drive shaft lever arm by means of a second ball joint. Thereby, a more flexible connection between the grate shaft lever arm and the corresponding drive shaft lever arm may be achieved. Furthermore, it may be possible to employ standard ball joints which are fully sealed and do not require any service for an extended period of time. This may be advantageous, especially in relation to ball joints located in the upper relatively narrow housing section where accessibility may be restricted. Furthermore, a ball joint may be better suitable for rocking motion back and forth as compared to standard ball bearings and may therefore last longer.
In a structurally particularly advantageous embodiment, the grate shafts of said at least one lane section are numbered consecutively in downward direction, the corresponding drive shafts are numbered correspondingly, each drive shaft is provided with a crank arm, the crank arms of drive shafts having odd numbers are connected by means of a first linking rod and the crank arms of drive shafts having even numbers are connected by means of a second linking rod, the actuator of said drive mechanism is a linear actuator, such as a hydraulic piston actuator, and the first linking rod and the second linking rod are interconnected by means of the linear actuator.
In an embodiment, each crank arm is mounted pivotally adjustably on the corresponding drive shaft. Thereby, the adjustment of the driven connection may be performed in the lower relatively broad housing section, thereby facilitating adjustment of clearance in connection with service and maintenance.
In an embodiment, each crank arm is mounted on the corresponding drive shaft elastically biased towards a predetermined relative pivotal position in relation to said drive shaft.
Thereby, if the movement of a grate shaft is prevented, the movement may wholly or partly be taken up by the elastic biasing mechanisms. Furthermore, by locating the respective elastic biasing mechanisms in the lower relatively broad housing section, the biasing mechanisms may be easily accessible, thereby facilitating service and maintenance.
In a structurally particularly advantageous embodiment, one of the drive shafts having odd numbers is connected to one of the drive shafts having even numbers by means of the synchronising mechanism of at the least one lane section.
In a structurally particularly advantageous embodiment, said synchronising mechanism includes a first synchronising lever arm having a first end fixedly connected to said one of the drive shafts having odd numbers and a second end pivotally connected to a first end of a synchronising rod and a second synchronising lever arm having a first end fixedly connected to said one of the drive shafts having even numbers and a second end pivotally connected to a second end of the synchronising rod.
In an embodiment, at least one midsection includes axially displaceable bearings in which corresponding grate shaft ends of at least one lane section are journalled, each said axially displaceable bearing is mounted in a displaceable bearing house mounted displaceably in relation to a stationary bearing house support mounted in fixed relationship to said at least one midsection so that said displaceable bearing house is displaceable in the axial direction of the corresponding grate shaft and fixed against rotation about said axial direction, a non-pivotal side cover plate is coupled to and axially displaceable with said displaceable bearing house, the non-pivotal side cover plate forms part of a side wall of the upper relatively narrow housing section of said at least one midsection including axially displaceable bearings, and the non-pivotal side cover plate is mounted in proximity to the outermost grate bars carried by the grate shafts of said at least one lane section. Thereby, axial displacements of grate shaft ends resulting from temperature changes of the grate shafts may be allowed for without changing the clearance between the non-pivotal side cover plate and the outermost rocking grate bars, thereby ensuring better control of the supply of combustion air. Furthermore, by coupling the non-pivotal side cover plate to the axially displaceable bearing house, a very slim midsection may be achieved even with displaceable non-pivotal side cover plates.
In a structurally particularly advantageous embodiment, the displaceable bearing house has an outer cylindrical surface arranged slidingly in a cylindrical boring in the stationary bearing house support.
In an embodiment, a pivotal side cover plate is fixed on each said grate shaft end journalled in an axially displaceable bearing, the pivotal side cover plate forms part of said side wall of the upper relatively narrow housing section, and the pivotal side cover plate is arranged pivotally in a cut-out of the corresponding non-pivotal side cover plate so that an outer edge of the pivotal side cover plate forming an arc of a circle is in close proximity to a corresponding inner edge of the cut-out of the corresponding non-pivotal side cover plate forming a corresponding arc of a circle. Thereby, a relatively tight connection may be formed between the non-pivotal side cover plate and the grate shaft end.
In a structurally particularly advantageous embodiment, the axially displaceable bearings are arranged at non-driven grate shaft ends. Depending on the drive mechanism, it may be advantageous that the driven grate shaft ends do not move in axial direction.
In a structurally particularly advantageous embodiment, in the at least one midsection including the drive mechanism and the synchronising mechanism of the at least one lane section, a stationary frame of said midsection is formed by means of two spaced grate beams extending in the longitudinal direction of said midsection in the lower relatively broad housing section of said midsection, two grate plates in the form of longitudinal L-formed brackets are mounted with a first lower flange on top of the respective spaced grate beams and with a second upright flange extending vertically, and bearing houses arranged in said midsection are carried by the respective second upright flanges of the two longitudinal L-formed brackets. Thereby, an especially narrow housing section of the midsection may be achieved.
In an embodiment, in the at least one midsection including the drive mechanism and the synchronising mechanism of the at least one lane section, a dust shield is arranged inside an outer enclosure of the at least one midsection, non-displaceable bearing houses or stationary bearing house supports carrying bearings in which respective driven grate shaft ends are journalled extend sealingly through respective openings in the dust shield, the dust shield thereby separates the inside of the outer enclosure of the at least one midsection into an outer room section next to the outer enclosure and an inner room section enclosing the drive mechanism including the actuator and the synchronising mechanism of at least one lane section. Thereby, the drive mechanism including the actuator and the synchronising mechanism may be even better protected against dust and dirt possibly entering through leaks from the combustion chamber. Thereby, maintenance costs may be reduced.
In an embodiment, the outer room section is connected to a supply of pressurised sealing gas. Thereby, an overpressure in relation to the pressure in the combustion chamber may be created in the outer room section, thereby even better preventing dust and dirt from possibly entering through leaks from the combustion chamber into the outer room section. The outer room section may thereby create a barrier between the combustion chamber and the inner room section, thereby even better preventing dust and dirt from possibly entering the inner room section enclosing the drive mechanism including the actuator and the synchronising mechanism. Thereby, maintenance costs may be even more reduced.
In a structurally particularly advantageous embodiment, the dust shield includes a bottom wall extending between the two spaced grate beams, two spaced side walls extending from the bottom wall to a top part of the upper relatively narrow housing section of said midsection and a top wall connecting the two spaced side walls, non-displaceable bearing houses or stationary bearing house supports carrying bearings in which respective grate shaft ends are journalled extends sealingly through openings in the respective two spaced side walls, and the drive mechanism of the at least one lane section extends through an opening in the bottom wall.
In a structurally particularly advantageous embodiment, the two spaced grate beams forming the stationary frame of said midsection have the form of hollow rectangular tubes, the inside of the hollow rectangular tubes are connected to a supply of pressurised sealing gas, and the pressurised sealing gas is supplied to the outer room section from the inside of the hollow rectangular tubes through holes in the walls of the hollow rectangular tubes.
In an embodiment, at least some of the grate bars of at least one grate lane extending between two midsections are adapted to be cooled by means of circulating cooling fluid, a cooling fluid supply channel is formed as an axial bore in an inlet end of the grate shafts carrying grate bars and a cooling fluid outlet channel is formed as an axial bore in an outlet end of the grate shafts carrying grate bars, the cooling fluid supply channels are connected to respective cooling fluid supply tubes extending in one of the two midsections, and the cooling fluid outlet channels are connected to respective cooling fluid return tubes extending in the other of the two midsections. Thereby, the service life of the grate bars may be extended substantially. By leading the cooling fluid in from one end of the grate shafts and out of the other end, an even better cooling effect may be achieved than that compared to known devices having inlet and outlet at one single end of the grate shafts.
In an embodiment, the non-pivotal side cover plates forming part of the side wall of the upper relatively narrow housing section of said at least one midsection and a top wall of said upper relatively narrow housing section are adapted to be cooled by means of circulating cooling fluid. Thereby, the service life of the grate shaft bearings and the drive mechanisms may be extended substantially.
In an embodiment, the left side section and the right side section include the drive mechanisms and the synchronising mechanisms of at least one lane section of the left outermost grate lane and of at least one lane section of the right outermost grate lane, respectively, the grate shafts of said at least one lane section of the left outermost grate lane and of said at least one lane section of the right outermost grate lane, respectively, are numbered consecutively in downward direction, each grate shaft is provided with a crank arm, the crank arms of grate shafts having odd numbers are connected by means of a first linking rod and the crank arms of grate shafts having even numbers are connected by means of a second linking rod, the actuator of said drive mechanism is a linear actuator, such as a hydraulic piston actuator, and the first linking rod and the second linking rod are interconnected by means of the linear actuator. Thereby, the same or corresponding drive mechanisms may be employed for both side sections and midsections, thereby reducing the number of different components.
In a structurally particularly advantageous embodiment, the movable grate includes a first grate lane, a second grate lane, and a third grate lane, the left side section and the right side section includes axially displaceable bearings for driven grate shaft ends of the first and third grate lanes, respectively, a first midsection includes axially non-displaceable bearings for non-driven grate shaft ends of the first grate lane and axially displaceable bearings for non-driven grate shaft ends of the second grate lane, and a second midsection includes axially non-displaceable bearings for driven grate shaft ends of the second grate lane and axially non-displaceable bearings for non-driven grate shaft ends of the third grate lane.
In a structurally particularly advantageous embodiment, the movable grate includes a first grate lane, a second grate lane, a third grate lane, and a fourth grate lane, the left side section and the right side section encloses axially displaceable driven grate shaft ends of the first and fourth grate lanes, respectively, a first midsection includes axially non-displaceable bearings for non-driven grate shaft ends of the first grate lane and axially displaceable bearings for non-driven grate shaft ends of the second grate lane, a second midsection includes axially non-displaceable bearings for driven grate shaft ends of the second grate lane and axially displaceable bearings for non-driven grate shaft ends of the third grate lane, and a third midsection includes axially non-displaceable bearings for driven grate shaft ends of the third grate lane and axially non-displaceable bearings for non-driven grate shaft ends of the fourth grate lane.
As seen in
Each grate shaft 12 has a driven grate shaft end 17 and a non-driven grate shaft end 18, and each grate shaft end 17, 18 is journalled in a respective bearing 19. As seen in
The grate bars 13 on each grate shaft 12 coincide with the grate bars 13 on the neighbouring shaft 12 without touching these, thereby forming the practically cohesive inclined grate surface 14. The gap between two coinciding grate bars 13 in the form of the predetermined clearance 82 mentioned just above may for instance be approximately 1 to 3 millimetres. The grate function is such that the grate shafts 12 alternately turn to their respective outer positions, and the inclined grate surface 14 thus forms a stair-shaped surface where the steps change direction. This produces a rolling movement to material present on the grate, which may have the effect of breaking it up and agitating it, while at the same time moving it forward in downward direction, thus achieving good exposure to radiant heat from the combustion chamber 83 and good exposure to combustion air.
In the embodiment of the invention illustrated in
Furthermore, as illustrated in
Furthermore, as illustrated in
Referring to
In principle, said driven connection could be any suitable means of drive transmission; however, in the illustrated embodiment, the driven grate shaft end 17 of each respective shaft 121, 122, 123, 124, 125, 126 is provided with a grate shaft lever arm 27, a first end 28 of the grate shaft lever arm 27 is in driving connection with the grate shaft 12 and a second end 29 of the grate shaft lever arm 27 is pivotally connected to a first end 30 of a corresponding connection rod 31. In the illustrated embodiment, the first end 28 of the grate shaft lever arm 27 is fixedly mounted on the driven grate shaft end 17 of the grate shaft 12 by means of bolts. Each said drive shaft 261, 262, 263, 264, 265, 266 is provided with a drive shaft lever arm 33, and a first end 34 of the drive shaft lever arm 33 is in driven connection with the drive shaft and a second end 35 of the drive shaft lever arm 33 is pivotally connected to a second end 32 of the corresponding connection rod 31. In the illustrated embodiment, the first end 34 of the drive shaft lever arm 33 is fixedly mounted on the drive shaft by means of bolts. Thereby, each grate shaft lever arm 27 is connected with a corresponding drive shaft lever arm 33 by means of a corresponding connection rod 31. Thereby, by driving each grate shaft by means of a connection rod, a precise transmission of the movement from the actuator to the grate shaft is possible. Furthermore, by driving each grate shaft independently by means of a respective connection rod extending down into the lower relatively broad housing section of the midsection, the movement of each grate shaft may be controlled independently from an easily accessible location, thereby facilitating precise control and adjustment of the movement of each separate grate shaft in connection with service and maintenance.
In the illustrated embodiment, each connection rod 31 is pivotally connected to the corresponding grate shaft lever arm 27 by means of a first ball joint 36, and each connection rod 31 is pivotally connected to the corresponding drive shaft lever arm 33 by means of a second ball joint 37. Thereby, a more flexible connection between the grate shaft lever arm and the corresponding drive shaft lever arm may be achieved. Furthermore, it may be possible to employ standard ball joints which are fully sealed and do not require any service for an extended period of time. Such standard ball joints are for instance used in the suspension and steering of cars. The use of such ball joints may be advantageous, especially in relation to ball joints located in the upper relatively narrow housing section where accessibility may be restricted. Furthermore, a ball joint may be better suitable for rocking motion back and forth as compared to standard ball bearings and may therefore last longer. If standard ball bearings are employed, these have to be provided with shaft seals. The shaft seals may not be very well suitable for the rocking motion back and forth and may therefore leak after extended use. Furthermore, the shaft seals may increase the size of the pivotal joint between the connection rod 31 and the corresponding drive shaft lever arm 33 or the corresponding grate shaft lever arm 27. This may be a disadvantage, because space may be limited in the upper relatively narrow housing section 15 of the respective midsections 9, 10.
Referring now to
A first end of each crank arm 38 is mounted pivotally adjustably on the corresponding drive shaft 26 and a second end of each crank arm 38 is connected pivotally to the corresponding first or second linking rod 39, 40 at a respective point thereof. Referring now to
By means of the above-described arrangement of the crank arms 38 on the respective drive shafts 26, the relative rotational position of each crank arm 38 in relation to the corresponding drive shaft 26 may be adjusted by rotation of the two corresponding set screws 85. The adjusted position may be fixed by tightening the locking nuts 107 on the respective set screws 85. Thereby, the adjustment of the driven connection may be performed in the lower relatively broad housing section, thereby facilitating adjustment of the individual clearance 82 between edge portions 23 of grate bars 13 in connection with service and maintenance.
Furthermore, by means of the stack of disc springs 86, each crank arm 38 is mounted on the corresponding drive shaft 26 elastically biased towards a predetermined relative pivotal position in relation to said drive shaft 26. Thereby, if the movement of a grate shaft is prevented, the movement may wholly or partly be taken up by the elastic biasing mechanisms in that one or more of the stacks of disc springs 86 is compressed between the guide 109 for disc springs and the top of the bore 108 in a respective end of the transverse upper part 87 of a crank arm 38. This may happen as an upper end of a respective set screw 85 presses on a respective head of a disc spring guide 109. Thereby, the upper ends of respective set screws 85 arranged at an end of a transverse upper part 87 opposed to an end pressing on a head may possibly be lowered or released from abutment with the respective head of a disc spring guide 109. By locating the respective elastic biasing mechanisms in the lower relatively broad housing section, the biasing mechanisms may be easily accessible, thereby facilitating service and maintenance.
It is noted that
Furthermore, it is seen in
In the illustrated embodiment, as explained above, each said drive shaft 261, 262, 263, 264, 265, 266 is provided with a drive shaft lever arm 33, and a first end 34 of the drive shaft lever arm 33 is in driven connection with the drive shaft and a second end 35 of the drive shaft lever arm 33 is pivotally connected to a second end 32 of the corresponding connection rod 31. However, in alternative embodiments, each connection rod 31 extending down into the lower relatively broad housing section 16 of a midsection 9, 10 is with its second end 32 located in said relatively broad housing section 16 in driven connection with the actuator 21 of said drive mechanism 20 by other means than illustrated. For instance, the second end 32 of connection rods 31 corresponding to grate shafts 12 having odd numbers may be connected by means of a first connection rod, and the second end 32 of connection rods 31 corresponding to grate shafts 12 having equal numbers may be connected by means of a second connection rod. The first and second connection rods may be connected by means of an actuator, such as a linear actuator or linear actuators or a rotary actuator or rotary actuators provided with two crank arms connected to the respective first and second connection rods. Appropriate synchronizing means may further be provided.
In these alternative embodiments, the driven connection between the second end 32 of said respective connection rods 31 and the actuator 21 of said drive mechanism 20 may be individually adjustable in order to adjust the individual predetermined clearance between edge portions 23 of grate bars 13 of neighbouring grate shafts 12. Thereby, the adjustment of the driven connection may be performed in the lower relatively broad housing section, thereby facilitating adjustment of clearance in connection with service and maintenance. Furthermore, in these alternative embodiments, the driven connection between the second end 32 of said respective connection rods 31 and the actuator 21 of said drive mechanism 20 may be individually elastically biased towards respective predetermined relative positions by means of respective biasing mechanisms located in the lower relatively broad housing section 16 of said midsections 9, 10. Thereby, if the movement of a grate shaft is prevented, the movement may wholly or partly be taken up by the biasing mechanisms. Furthermore, by locating the respective biasing mechanisms in the lower relatively broad housing section 16, the biasing mechanisms may be easily accessible, thereby facilitating service and maintenance.
Referring to
As seen in
As furthermore seen in
Because the pivotal side cover plate 57 is fixed on the grate shaft end 18, it will follow axial displacements of the grate shaft end 18 resulting from temperature changes of the grate shaft 12, and the pivotal side cover plate 57 will therefore also follow the displacements of the non-pivotal side cover plate 53.
Axially displaceable bearings 50 as discussed above may be arranged at driven shaft grate shaft ends 17 or at non-driven grate shaft ends 18. However, for structural reasons, it may be preferred to arrange such axially displaceable bearings 50 only at non-driven grate shaft ends 18. Depending on the drive mechanism, it may be advantageous that the driven grate shaft ends do not move in axial direction.
As seen in
A dust shield 65 is arranged inside an outer enclosure 66 of each respective midsection 8, 9, 10. Non-displaceable bearing houses 64 and stationary bearing house supports 52 carrying bearings 19 in which respective driven grate shaft ends 17 are journalled extend sealingly through respective openings 67 in the dust shields 65. The dust shield 65 thereby separates the inside of the outer enclosure 66 of each midsection into an outer room section 68 next to the outer enclosure 66 and an inner room section 69. In the second and third midsections 9, 10, the inner room section 69 encloses the drive mechanism 20 including the actuator 21 and the synchronising mechanism 22 of each lane section 11. Thereby, the drive mechanism including the actuator and the synchronising mechanism may be even better protected against dust and dirt possibly entering through leaks from the combustion chamber. Thereby, maintenance costs may be reduced.
The outer room section 68 is connected to a supply of pressurised sealing gas. Thereby, an overpressure in relation to the pressure in the combustion chamber 83 may be created in the outer room section 68, thereby even better preventing dust and dirt from possibly entering through leaks from the combustion chamber into the outer room section. The outer room section 68 may thereby create a barrier between the combustion chamber 83 and the inner room section 69, thereby even better preventing dust and dirt from possibly entering the inner room section enclosing the drive mechanism including the actuator and the synchronising mechanism. Thereby, maintenance costs may be even more reduced.
The dust shield 65 includes a bottom wall 70 extending between the two spaced grate beams 60, two spaced side walls 71 extending from the bottom wall 70 to a top part of the upper relatively narrow housing section 15 of the midsections 8, 9, 10 and a top wall 72 connecting the two spaced side walls 71. In the second and third midsections 9, 10, non-displaceable bearing houses 64 and stationary bearing house supports 52 carrying bearings 19 in which respective grate shaft ends 17, 18 are journalled extend sealingly through openings 67 in the respective two spaced side walls 71, and the drive mechanism 20 of each lane section 11 extends through an opening 73 in the bottom wall 70.
The bearings 19 carried by the non-displaceable bearing houses 64 and stationary bearing house supports 52 are sealed against the outer room section 68 and possibly against the inner room section 69, respectively, by means of corresponding stacks 81 of disc springs.
As seen in
In the embodiment illustrated in
Referring to
Referring to
As best seen in
Referring again to
Furthermore, it is seen in
In the embodiment illustrated in
As described above, in the embodiment illustrated in
By comparing the embodiments of
Furthermore, it may be understood that the embodiment of
According to the present invention, other embodiments than those described above and illustrated in the figures are possible. For instance, the embodiment illustrated in
As another example, the embodiment illustrated in
The different embodiments described above may be combined in any suitable way. On the basis of the above, the skilled person will understand that many further embodiments according to the present invention are possible.
This application is a U.S. national stage of PCT/IB2016/054082, filed Jul. 7, 2016, the entire content of which is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2016/054082 | 7/7/2016 | WO | 00 |
