EP4303492A1 - Plattenförmiges rostelement für einen beweglichen rost eines ofens - Google Patents

Plattenförmiges rostelement für einen beweglichen rost eines ofens Download PDF

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Publication number
EP4303492A1
EP4303492A1 EP22183611.7A EP22183611A EP4303492A1 EP 4303492 A1 EP4303492 A1 EP 4303492A1 EP 22183611 A EP22183611 A EP 22183611A EP 4303492 A1 EP4303492 A1 EP 4303492A1
Authority
EP
European Patent Office
Prior art keywords
plate
grate
grate element
wall
cooling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22183611.7A
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English (en)
French (fr)
Inventor
Hans BØGH ANDERSEN
Morten Ryge BØGILD
Thomas Schaldemose NORMAN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Babcock and Wilcox Volund AS
Original Assignee
Babcock and Wilcox Volund AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Babcock and Wilcox Volund AS filed Critical Babcock and Wilcox Volund AS
Priority to EP22183611.7A priority Critical patent/EP4303492A1/de
Priority to TW112125486A priority patent/TW202413846A/zh
Priority to PCT/EP2023/068868 priority patent/WO2024008930A1/en
Publication of EP4303492A1 publication Critical patent/EP4303492A1/de
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23H—GRATES; CLEANING OR RAKING GRATES
    • F23H7/00—Inclined or stepped grates
    • F23H7/06—Inclined or stepped grates with movable bars disposed parallel to direction of fuel feeding
    • F23H7/10—Inclined or stepped grates with movable bars disposed parallel to direction of fuel feeding rocking about their axes

Definitions

  • the present invention relates to a plate-formed grate element for a movable grate of a furnace, the movable grate including a number of pivotal grate shafts carrying plate-formed grate elements and thereby defining an inclined grate surface, the movable grate including a drive mechanism being arranged 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, and the movable grate including a synchronising mechanism being arranged to maintain a predetermined clearance between edge portions of plate-formed grate elements of neighbouring grate shafts during the pivoting movement of the grate shafts, the plate-formed grate element having a top wall, a front end and a back end, a longitudinal direction of the plate-formed grate element extending between the front end and the back end, the front end of the plate-formed grate element having a lower inwardly curved
  • WO 2018/007854 A1 discloses movable grates for a combustion furnace.
  • the movable grate includes a number of pivotal grate shafts carrying plate-formed grate elements, neighbouring grate shafts being arranged for pivoting back and forth in opposite rotational directions so as to maintain a predetermined clearance between edge portions of the plate-formed grate elements of the neighbouring grate shafts.
  • the plate-formed grate elements have a front end with a relatively pointed front tip edge and a back end with a relatively pointed back tip edge.
  • Each plate-formed grate element has a top wall and a straight front wall forming an oblique angle with the top wall and extending from the top wall to a position of the pointed front tip edge which is below or at level with a general lower surface of the plate-formed grate element.
  • the straight front wall is connected with the general lower surface of the plate-formed grate element by means of a lower inwardly curved wall portion adapted to form said predetermined clearance with a back end of another plate-formed grate element.
  • the predetermined clearance between the individual plate-formed grate elements, on which material intended for combustion is placed provides for supplying primary air for the combustion.
  • the prior art plate-formed grate elements may suffer from excessive wear of the pointed front tip edge of the front end of the grate elements.
  • significant compressive stress may cause plastic deformation of the pointed front tip edge during operation.
  • the pointed front tip edge may experience high tensile stress due to the plastic deformation which may result in micro cracks in the front tip edge. Corrosion caused by high concentrations of heavy metals in the fuel may further aggravate the wear of the front tip edge.
  • US 4,275,706 relates to air-cooled grate bars, in particular for mechanically conveying mechanical grates such as pivot step grates.
  • a cap of U-shape which is provided over the respective grate bar forms an air channel on top of the grate bar. Cooling air is injected into the channel through an inlet air tube extending downwards from a lower open side of the grate bar. The air exits from the channel at either end of the grate bar, whereby the air is guided through holes to the lower side of the grate bar. From there, the air flows up through gaps between neighbouring grate bars to the combustion chamber.
  • the air channel on top of the grate bar therefore forms part of an open air cooling path and is not adapted for or suitable for cooling by means of combustion air rising freely from a lower chamber formed below the grate bars.
  • the grate bar is articulately mounted, and at this end, considered in side view, it has a lower curved section forming a bearing.
  • the grate bar is adapted to overlap a corresponding front end of another grate bar.
  • DE 33 43 024 A1 relates to similar air-cooled grate bars.
  • US 5,033,396 discloses a grill arrangement, particularly for stepped pivoting grills, comprising feeding means, possibly drying and firing grills and at least one vertical grill with associated horizontal grill as well as following burnout grill.
  • the air supply of the pivoting fuel elements is provided in particular for cooling the grill bars.
  • To each grill bar in the centre cooling air is supplied from below, for example from an air distributing box which can be provided within or outside an air funnel.
  • the air is guided via a cap welded for example onto the grill bar upper side.
  • the centrally supplied air leaves at the end face on the one hand in the region of the pivot mounting for the grill bars and on the other hand in the region of the opposite grill bar end.
  • an air channel of the grate bar therefore forms part of an open air cooling path and is not adapted for or suitable for cooling by means of combustion air rising freely from a lower chamber formed below the grate bars.
  • the object of the present invention is to provide a plate-formed grate element being less prone to wear.
  • the plate-formed grate element has an outwardly curved front wall extending from the top wall of the plate-formed grate element to the lower inwardly curved wall portion of the front end, a front tip edge of the front end is formed by the outwardly curved front wall at its connection with the lower inwardly curved wall portion, the outwardly curved front wall has a nominal wall thickness varying by less than ⁇ 35 per cent, and the at least one cooling rib extends further into an area formed between the outwardly curved front wall and the lower inwardly curved wall portion of the front end and is connected to both the outwardly curved front wall and the lower inwardly curved wall portion.
  • combustion air flows into a cooling area or chamber formed in the front end of the plate-formed grate element whereby the cooling combustion air may contact the inside of the outwardly curved front wall and the inside of the lower inwardly curved wall portion of the front end and thereby efficiently cool the front end and in particular the area at the front tip edge.
  • combustion air contacting the at least one cooling rib extending into said cooling chamber and being connected to the outwardly curved front wall and the lower inwardly curved wall portion of the front end may further cool the area of the front tip edge.
  • the cooling effect of the combustion air is evened out over the outwardly curved front wall, as compared to the prior art grate elements, thereby cooling the front tip edge better and more efficiently.
  • a better cooling of the front tip edge may result in less wear of the front tip and therefore a longer service life of the plate-formed grate elements.
  • a smooth curvature of the entire outwardly curved front wall may result in a stronger front wall without weak areas in which tension may build up.
  • the nominal wall thickness of the outwardly curved front wall varies by less than ⁇ 30 per cent, preferably less than ⁇ 25 per cent, and most preferred less than ⁇ 20 per cent.
  • the outwardly curved front wall has an at least substantially constant wall thickness.
  • the part of the outwardly curved front wall extending from the top wall of the plate-formed grate element to the front tip edge has an outer contour with a first nominal radius of curvature varying by less than ⁇ 40 per cent, and preferably less than ⁇ 20 per cent
  • the front tip edge has an outer contour with a second nominal radius of curvature varying by less than ⁇ 20 per cent
  • the first nominal radius of curvature is more than 2 times larger, preferably more than 3 times larger, more preferred more than 4 times larger and most preferred more than 5 times larger than the second nominal radius of curvature.
  • the at least one cooling rib includes a first cooling rib forming a first side wall of the plate-formed grate element and a second cooling rib forming a second side wall of the plate-formed grate element, the second side wall being opposed to the first side wall.
  • a cooling chamber may formed in the front end of the plate-formed grate element whereby the cooling combustion air may contact the inside of the outwardly curved front wall and the inside of the lower inwardly curved wall portion of the front end and thereby efficiently cool the front end and in particular the area at the front tip edge, thereby resulting in less wear at the front tip edge.
  • the at least one cooling rib further includes a number of intermediate cooling ribs arranged between the first cooling rib and the second cooling rib.
  • the cooling ribs are sealingly connected to both the outwardly curved front wall and the lower inwardly curved wall portion so that separate cooling chambers are formed between neighbouring cooling ribs at the front end of the plate-formed grate element, and each one of said separate cooling chambers is accessible for combustion air through an opening formed between respective neighbouring cooling ribs and behind the front end of the plate-formed grate element.
  • the top wall of the plate-formed grate element is at least substantially flat when seen in longitudinal cross-section, and a part of the top wall extends over at least a part of the lower inwardly curved wall portion of the plate-formed grate element.
  • the top wall extends over at least 30 per cent, preferably at least 40 per cent, and most preferred at least 50 per cent, of the extent of the lower inwardly curved wall portion in the longitudinal direction of the plate-formed grate element.
  • a connection point between the top wall and the outwardly curved front wall is located in front of an apex of the lower inwardly curved wall portion by a distance in the longitudinal direction of the plate-formed grate element.
  • the outwardly curved front wall is at least substantially symmetric about a symmetry line forming an angle of at least substantially 45 degrees with the longitudinal direction of the plate-formed grate element.
  • the present invention further relates to a furnace with a movable grate including a number of plate-formed grate elements as described above.
  • Figs. 3 to 12 illustrate a full-sized air-cooled plate-formed grate element 1, according to the present invention, for use in a movable grate 5 of a furnace of the type illustrated in Figs. 17 and 18 .
  • air-cooled is understood cooled by means of combustion gas or air.
  • the movable grate 5 includes a number of pivotal grate shafts 6 carrying plate-formed grate elements 1, 2, 3 and thereby defining an inclined grate surface 7.
  • the pivotal grate shafts 6 are illustrated in further detail in Figs. 16 and 19 to 21 . Referring to Fig.
  • the movable grate 5 further includes a drive mechanism 8 being arranged for pivoting back and forth neighbouring grate shafts 6 in opposite rotational directions so as to impart a wave-like movement to material on the grate surface 7 in order to transport such material downwards.
  • the drive mechanism 8 is arranged so that each grate shafts 6 is provided with a crank arm 63, the crank arms of every other grate shafts 6 are connected by means of a first linking rod 61 and the crank arms 63 of the remaining grate shafts 6 are connected by means of a second linking rod 62, the actuator of said drive mechanism is a linear actuator 60, such as a hydraulic piston actuator, and the first linking rod 61 and the second linking rod 62 are interconnected by means of the linear actuator 60.
  • the crank arms 63 may be mounted on separate shafts connected to the respective grate shafts 6 via separate crank systems or via any other suitable mechanical drive connection.
  • the movable grate 5 further includes a synchronising mechanism 9 being arranged to maintain a predetermined clearance 10 (so small that it is not distinguishable in the figures) between edge portions 11 of plate-formed grate elements 1, 2, 3 of neighbouring grate shafts 6 during the pivoting movement of the grate shafts 6.
  • the synchronising mechanism 9 includes a first synchronising lever arm 58 having a first end fixedly connected to one of the grate shafts 6 connected to the first linking rod 61 and a second synchronising lever arm 59 having a first end fixedly connected to one of the grate shafts 6 connected to the second linking rod 62.
  • the second ends of the respective first and second synchronising lever arms 58, 59 are pivotally connected to respective ends of a synchronising rod 57.
  • the synchronising mechanism 9 may maintain said predetermined clearance between edge portions of plate-formed grate elements 1, 2, 3 of neighbouring grate shafts 6.
  • the mutual relative pivotal positions of the respective grate shafts 6 of the movable grate 5 may be individually elastically biased towards respective predetermined relative pivotal positions by means of respective biasing mechanisms in the form of disc springs 64 arranged in respective mounting brackets of the crank arm 63 on the grate shafts 6. Thereby, if the movement of a grate shaft 6 is prevented, the movement may wholly or partly be taken up by the biasing mechanisms.
  • the plate-formed grate elements 1, 2, 3 on each grate shaft 6 coincide with the plate-formed grate elements 1, 2, 3 on the neighbouring shaft 6 without touching these, thereby forming the practically cohesive inclined grate surface 7.
  • the gap between two coinciding plate-formed grate elements 1, 2, 3 in the form of the predetermined clearance 10 mentioned just above may for instance be approximately 1 to 3 millimetres.
  • the grate function is such that the grate shafts 6 alternately turn to their respective outer positions, as illustrated in Figs. 16A and 16 C , respectively, thereby passing their intermediate position, as illustrated in Fig. 16B , and the inclined grate surface 7 thus forms a stair-shaped surface where the steps change direction.
  • Fig. 18 illustrates a complete movable grate 5 for a not shown furnace.
  • the movable grate 5 has a left grate lane 41 and a right grate lane 42.
  • the illustrated type of movable grate 5 may have any suitable number of grate lanes, such as one, two, three, four or even more grate lanes.
  • Fig. 17 illustrates a longitudinal section through the right grate lane 42 of the movable grate 5 of Fig. 18 .
  • Each grate lane 41, 42 has a first section 43, on which the fuel enters, a second section 44, a third section 45, and a fourth section 46, from which the fuel finally exits. More sections may be provided.
  • the first and second sections 43, 44 may therefore typically include mainly plate-formed grate elements provided with internal cooling fluid chambers through which a cooling fluid, typically a liquid, such as water, is circulated.
  • a cooling fluid typically a liquid, such as water
  • the plate-formed grate elements are described in detail in applicant's pending application PCT/EP2021/086204 .
  • the plate-formed grate elements arranged along the sides of the grate lanes 41, 42 of the first and second sections 43, 44 may be air-cooled and of the type according to the present invention. This may be due to the fact that less fuel reaches the side areas of the grate lanes 41, 42 and therefore cooling requirements may be reduced.
  • the third and fourth sections 45, 46 may typically be cooled entirely by means of primary combustion air and all full-sized and so-called first half plate-formed grate elements 1, 2 of these sections may therefore be of the type according to the present invention.
  • Figs. 16A, 16B and 16C illustrate different stages of operation of the third section 45 of the right grate lane 42 of the movable grate 5 illustrated in Fig. 18 .
  • the third section 45 of the right grate lane 42 includes from left to right, a so-called first half plate-formed grate element 2, four full-sized plate-formed grate elements 1 arranged in succession and a so-called last half plate-formed grate element 3.
  • the designation "half" simply refers to a reduced length of the first and last plate-formed grate elements 2, 3, as compared to the full-sized plate-formed grate elements 1.
  • first half plate-formed grate element 2 has a specific design of its back end 15 and the last half plate-formed grate element 3 has a specific design of its front end 14, as it will be explained in further detail in the following.
  • a back end 15 of the first half plate-formed grate element 2 of the fourth section 46 cooperates with a fixed plate-formed grate element 4.
  • a back end 15 of the first half plate-formed grate element 2 of the third section 45 cooperates with a fixed plate-formed grate element 4, however, in Fig.
  • the first half plate-formed grate element 2 of the third section 45 and the corresponding fixed plate-formed grate element 4 are not visible, because the movable grate 5 has been illustrated broken up in parts as illustrated by broken lines.
  • the back end 15 of the first half plate-formed grate element 2 of the third section 45 to cooperate with the corresponding fixed plate-formed grate element 4, the back end 15 of the first half plate-formed grate element 2 is shorter and has a rounded contour as compared to the back end 15 of the full-sized plate-formed grate elements 1.
  • the first half plate-formed grate element 2 according to the present invention is illustrated in Figs. 13 to 15 . Referring again to Fig.
  • the front end 14 of the first half plate-formed grate element 2 cooperates with the back end 15 of the first one of the four full-sized plate-formed grate elements 1 in the same way as the front end 14 of each of the first, second and third full-sized plate-formed grate element 1 cooperates with the back end 15 of a neighbouring full-sized plate-formed grate element 1.
  • the front end 14 of the last (fourth) full-sized plate-formed grate element 1 cooperates with a back end 15 of the last half plate-formed grate element 3 in the same way as the front end 14 of a full-sized plate-formed grate element 1 cooperates with the back end 15 of a neighbouring full-sized plate-formed grate element 1.
  • a front end 14 of the last half plate-formed grate element 3 of the third section 45 cooperates with a fixed plate-formed grate element 4 arranged between the third section 45 of the grate lane 42 and the fourth section 46 of the grate lane 42.
  • the front end 14 of the last half plate-formed grate element 3 is shorter and has a different contour as compared to the front end 14 of the full-sized plate-formed grate elements 1.
  • the front end 14 of the last half plate-formed grate element 3 during operation is located below the fixed plate-formed grate element 4, the front end 14 of the last half plate-formed grate element 3 is subjected to lower temperatures than the front end 14 of the first half plate-formed grate element 2 and the front end 14 of each of the four full-sized plate-formed grate elements 1. Therefore, the requirement for cooling of the front end 14 of the last half plate-formed grate element 3 is relatively low and is not designed according to the present invention.
  • the front end 14 of the first half plate-formed grate element 2 is during operation located above the back end 15 of the first one of the four full-sized plate-formed grate elements 1 in the same way as the front end 14 of each full-sized plate-formed grate element 1 is during operation located above the back end 15 of a neighbouring full-sized plate-formed grate element 1 or above the back end 15 of the last half plate-formed grate element 3. Therefore, the front end 14 of the first half plate-formed grate element 2 and the front end 14 of each full-sized plate-formed grate element 1 are subjected to extremely high temperatures caused by the combustion of fuel on the movable grate 5 during operation.
  • the requirement for cooling of the front end 14 of the first half plate-formed grate element 2 and the front end 14 of each full-sized plate-formed grate element 1 is very high in order to avoid excessive wear.
  • An embodiment of the full-sized plate-formed grate element 1 according to the present invention is illustrated in Figs. 3 to 12 and 20
  • an embodiment of the first half plate-formed grate element 2 according to the present invention is illustrated in Figs. 13 to 15 and 21 .
  • the plate-formed grate elements 1, 2 according to the present invention are less prone to wear of in particular the front tip edge 23, as it will be explained in further detail below.
  • the plate-formed grate element 1 has a top wall 12, a front end 14 and a back end 15. As indicated in Fig. 3 , a longitudinal direction L of the plate-formed grate element 1, 2 extends between the front end 14 and the back end 15.
  • the front end 14 of the plate-formed grate element 1 has a lower inwardly curved wall portion 16 being adapted to maintain said predetermined clearance 10 with a back tip edge 17 of the back end 15 of a corresponding plate-formed grate element 1 during part of said pivoting movement of the grate shafts 6 when said plate-formed grate elements 1 are arranged on neighbouring grate shafts 6.
  • the pivoting movement of the grate shafts 6 is illustrated in Figs. 16A-C .
  • the plate-formed grate element 1, 2 is adapted to be cooled by means of combustion air coming from a lower chamber 51 formed below the movable grate 5 in the furnace as indicated in Figs. 17 and 18 .
  • this is achieved in that the top wall 12 of the plate-formed grate element 1 is provided with at least one cooling rib 18, 19, 20, 21 projecting downwardly from a lower side of the top wall 12 and extending in the longitudinal direction L of the plate-formed grate element 1 and being freely exposed to combustion air coming from below.
  • the at least one cooling rib 18, 19, 20, 21 is freely exposed to combustion air coming from below, because the plate-formed grate element 1 is not provided with any bottom wall or similar element below the at least one cooling rib 18, 19, 20, 21 which could hinder the airflow to or from said at least one cooling rib.
  • the plate-formed grate element 1 is provided with four cooling ribs 18, 19, 20, 21, however, any suitable number of cooling ribs may be employed.
  • the furnace as illustrated in Figs. 17 and 18 comprises a not shown air supply configured for supplying primary air for the combustion from beneath and through the movable grate 5 and through the layer of fuel situated on the grate during operation.
  • This combustion air coming from the lower chamber 51 formed below the movable grate 5 also serves as cooling air for the plate-formed grate elements of the grate as mentioned above.
  • Said air supply is often referred to as underfire air.
  • overfire air may be supplied to the furnace above the grate 5.
  • Figs. 1 and 2 illustrate a known air-cooled plate-formed grate element 52.
  • This prior art plate-formed grate element 52 also has a top wall 12 being generally flat, a front end 14 and a back end 15.
  • the front end 14 of the plate-formed grate element 1 has a lower inwardly curved wall portion 16 being adapted to maintain said predetermined clearance 10 with a back tip edge 17 of the back end 15 of a corresponding plate-formed grate element 1 during part of said pivoting movement of the grate shafts 6 when said plate-formed grate elements 1 are arranged on neighbouring grate shafts 6.
  • the top wall 12 of the prior art plate-formed grate element 52 is provided with four cooling ribs 18, 19, 20, 21 projecting downwardly from the top wall 12 and extending in a longitudinal direction of the plate-formed grate element 52.
  • the prior art plate-formed grate element 52 of Figs. 1 and 2 has a straight front wall 53 extending from the top wall 12 of the prior art plate-formed grate element 52 to the lower inwardly curved wall portion 16 of the front end 14. As seen, the straight front wall 53 forms an oblique angle with the top wall 12 and forms a pointed front tip edge 54 at its connection with the lower inwardly curved wall portion 16. As seen in Figs. 1 and 2 , the entire front end 14 of the prior art plate-formed grate element 52, i.e. an area 24 formed between the straight front wall 53 and the lower inwardly curved wall portion 16 of the front end 14, is formed by solid material.
  • the solid material extends along the front end 14 from a left side 65 of the plate-formed grate element 52 to a right side 66 of the plate-formed grate element 52.
  • the thickness of this solid material varies greatly along the straight front wall 53 from a connection 25 between the top wall 12 and the straight front wall 53 to the pointed front tip edge 54.
  • said thickness is relatively small, at the middle of the straight front wall 53, said thickness is relatively large, and at the pointed front tip edge 54, said thickness is relatively small, although thicker than the thickness at the connection 25 between the top wall 12 and the straight front wall 53.
  • the pointed front tip edge 54 of the prior art plate-formed grate element 52 may during operation be subject to a significant temperature gradient due to a substantial mass concentration at the front end 14 and at the pointed front tip edge 54 in the form of the solid material in the area 24 formed between the straight front wall 53 and the lower inwardly curved wall portion 16 of the front end 14. Furthermore, as seen, the four cooling ribs 18, 19, 20, 21 of the prior art plate-formed grate element 52 end before reaching the front end 14 which is relatively distant from the pointed front tip edge 54 at which the temperature may be elevated. The temperature of the pointed front tip edge 54 may during operation reach up to about 900 degrees Celsius.
  • the plate-formed grate element 1 has an outwardly curved front wall 22 extending all the way from the top wall 12 of the plate-formed grate element 1 to the lower inwardly curved wall portion 16 of the front end 14.
  • a front tip edge 23 of the front end 14 is formed by the outwardly curved front wall 22 at its connection with the lower inwardly curved wall portion 16, and the outwardly curved front wall 22 has a nominal wall thickness varying by less than ⁇ 35 per cent.
  • the at least one cooling rib 18, 19, 20, 21 extends further into an area 13 formed between the outwardly curved front wall 22 and the lower inwardly curved wall portion 16 of the front end 14 and is connected to both the outwardly curved front wall 22 and the lower inwardly curved wall portion 16.
  • Combustion air may therefore flow into one or more cooling areas or cooling chambers 32 formed in the front end 14 of the plate-formed grate element 1 whereby the cooling combustion air may contact the inside of the outwardly curved front wall 22 and the inside of the lower inwardly curved wall portion 16 of the front end 14 and thereby efficiently cool the front end 14 and in particular the area at the front tip edge 23.
  • combustion air contacting the at least one cooling rib 18, 19, 20, 21 extending into said cooling chamber or chambers and being connected to the outwardly curved front wall 22 and the lower inwardly curved wall portion 16 of the front end 14 may further cool the area of the front tip edge 23.
  • the outwardly curved front wall 22 has a nominal wall thickness varying by less than ⁇ 35 per cent, the cooling effect of the combustion air is evened out over the outwardly curved front wall 22, as compared to the prior art grate elements, thereby cooling the front tip edge 23 better and more efficiently.
  • a better cooling of the front tip edge 23 may result in less wear of the front tip edge and therefore a longer service life of the plate-formed grate elements 1.
  • a smooth curvature of the entire outwardly curved front wall 22 may result in a stronger front wall without weak areas in which tension may build up.
  • the temperature of the front tip edge 23 of the plate-formed grate element 1 according to the present invention may during operation reach no more than 300 degrees Celsius in a furnace setup in which the pointed front tip edge 54 of the prior art plate-formed grate element 52 of Figs. 1 and 2 would reach almost 900 degrees Celsius.
  • a temperature reduction of up to about 600 degrees Celsius may be obtained by means of the plate-formed grate element 1 according to the invention.
  • the top wall 12 of the plate-formed grate element 1 is generally at least substantially flat.
  • the top wall 12 has an at least substantially constant wall thickness.
  • a nominal wall thickness of the top wall 12 of the plate-formed grate element 1 may advantageously vary by less than ⁇ 35 per cent, preferably less than ⁇ 30 per cent, more preferred less than ⁇ 25 per cent, and most preferred less than ⁇ 20 per cent.
  • the outwardly curved front wall 22 is continuously rounded from the top wall 12 of the plate-formed grate element 1 to the lower inwardly curved wall portion 16 of the front end 14 so that the outwardly curved front wall 22 forms a convex part of the front end 14 and the lower inwardly curved wall portion 16 forms a concave part of the front end 14.
  • an upper surface of the top wall 12 of the plate-formed grate element 1 slopes from both sides towards a central area of the upper surface when seen in a transverse cross-section.
  • a central line 50 illustrated in Fig. 12 forms the lowest point of said upper surface as seen in the cross-sections.
  • Said slope of the top surface forms a kind of trough leading possible fluid further down the plate-formed grate element 1 and away therefrom.
  • the first half plate-formed grate element 2 also has an outwardly curved front wall 22 extending from the top wall 12 of the plate-formed grate element 2 to the lower inwardly curved wall portion 16 of the front end 14.
  • a front tip edge 23 of the front end 14 is formed by the outwardly curved front wall 22 at its connection with the lower inwardly curved wall portion 16, and the outwardly curved front wall 22 has a nominal wall thickness varying by less than ⁇ 35 per cent.
  • the at least one cooling rib 18, 19, 20, 21 extends further into an area 13 formed between the outwardly curved front wall 22 and the lower inwardly curved wall portion 16 of the front end 14 and is connected to both the outwardly curved front wall 22 and the lower inwardly curved wall portion 16.
  • Combustion air may therefore flow into a cooling area or chamber formed in the front end 14 of the plate-formed grate element 2 whereby the cooling combustion air may contact the inside of the outwardly curved front wall 22 and the inside of the lower inwardly curved wall portion 16 of the front end 14 and thereby efficiently cool the front end 14 and in particular the area at the front tip edge 23.
  • the design of the back end 15 of the first half plate-formed grate element 2 differs from the design of the back end 15 of the full-sized plate-formed grate element 1. Comparing Figs. 5 and 14 , it is seen that the back end 15 of the first half plate-formed grate element 2 is shorter than the back end 15 of the full-sized plate-formed grate element 1. Furthermore, the back end 15 of the first half plate-formed grate element 2 is rounded with a relatively large radius of curvature in order to cooperate with a fixed plate-formed grate element 4 as discussed above and as illustrated in Figs. 16A to 16C .
  • the plate-formed grate element 1, 2 according to the present invention may preferably be produced in one single piece of metal in a sand casting process. Subsequently, the casting may be machined to accurate measurements.
  • the sand casting process may for instance be of the lost foam type or any other suitable sand casting process.
  • the plate-formed grate element 1, 2 according to the present invention may be produced in any suitable way, such as by any suitable casting process or machining process or even in a 3D printing process.
  • the plate-formed grate element 1, 2 may also be assembled from any suitable number of elements.
  • the nominal wall thickness of the outwardly curved front wall 22 of the plate-formed grate element 1, 2 according to the present invention may advantageously vary by less than ⁇ 30 per cent, preferably less than ⁇ 25 per cent, and most preferred less than ⁇ 20 per cent.
  • the outwardly curved front 22 wall has an at least substantially constant wall thickness.
  • the part of the outwardly curved front wall 22 extending from the top wall 12 of the plate-formed grate element 1, 2 to the front tip edge 23 may advantageously have an outer contour with a first nominal radius of curvature R varying by less than ⁇ 40 per cent, and preferably less than ⁇ 20 per cent.
  • the front tip edge 23 may advantageously have an outer contour with a second nominal radius of curvature r varying by less than ⁇ 20 per cent.
  • the first nominal radius of curvature R is more than 2 times larger, preferably more than 3 times larger, more preferred more than 4 times larger and most preferred more than 5 times larger than the second nominal radius of curvature r.
  • the outwardly curved front wall 22 of the plate-formed grate element 1, 2 may advantageously have an outer contour with a first nominal radius of curvature R, wherein the first nominal radius of curvature R is constant, constantly increases or constantly decreases, from the top wall 12 of the plate-formed grate element 1, 2 to the front tip edge 23.
  • the at least one cooling rib 18, 19, 20, 21 includes a first cooling rib 18 forming a first side wall of the plate-formed grate element 1, 2 and a second cooling rib 21 forming a second side wall of the plate-formed grate element, the second side wall being opposed to the first side wall.
  • one or more cooling chambers 32 may be formed in the front end 14 of the plate-formed grate element 1 whereby the cooling combustion air may contact the inside of the outwardly curved front wall 22 and the inside of the lower inwardly curved wall portion 16 of the front end 14 and thereby efficiently cool the front end 14 and in particular the area at the front tip edge 23, thereby resulting in less wear at the front tip edge.
  • the at least one cooling rib 18, 19, 20, 21 further includes two intermediate cooling ribs 19, 20 arranged between the first cooling rib 18 and the second cooling rib 21. Thereby, an even better cooling effect and therefore less wear may be experienced at the area of the front tip edge 23.
  • more or less than two intermediate cooling ribs may be provided.
  • the cooling ribs 18, 19, 20, 21 are sealingly connected to both the outwardly curved front wall 22 and the lower inwardly curved wall portion 16 so that separate cooling chambers 67 are formed between neighbouring cooling ribs 18, 19, 20, 21 at the front end 14 of the plate-formed grate element 1, 2, and wherein each one of said separate cooling chambers 67 is accessible for combustion air through an opening 68 formed between respective neighbouring cooling ribs 18, 19, 20, 21 and behind the front end 14 of the plate-formed grate element 1, 2.
  • an even better cooling effect and therefore less wear may be experienced at the area of the front tip edge 23.
  • the top wall 12 of the plate-formed grate element 1 is at least substantially flat when seen in longitudinal cross-section, and a part 69 of the top wall 12 extends over at least a part of the lower inwardly curved wall portion 16 of the plate-formed grate element.
  • the part 69 of the top wall 12 is connected to the outwardly curved front wall 22 at a connection point 33 illustrated in Figs. 4 and 5 .
  • the outwardly curved front wall 22 is at least substantially symmetric about a symmetry line S forming an angle of at least substantially 45 degrees with the longitudinal direction L of the plate-formed grate element 1, 2.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Incineration Of Waste (AREA)
  • Furnace Details (AREA)
EP22183611.7A 2022-07-07 2022-07-07 Plattenförmiges rostelement für einen beweglichen rost eines ofens Pending EP4303492A1 (de)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP22183611.7A EP4303492A1 (de) 2022-07-07 2022-07-07 Plattenförmiges rostelement für einen beweglichen rost eines ofens
TW112125486A TW202413846A (zh) 2022-07-07 2023-07-07 用於爐子之可移動爐排的板狀爐排元件
PCT/EP2023/068868 WO2024008930A1 (en) 2022-07-07 2023-07-07 Plate-formed grate element for a movable grate of a furnace

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22183611.7A EP4303492A1 (de) 2022-07-07 2022-07-07 Plattenförmiges rostelement für einen beweglichen rost eines ofens

Publications (1)

Publication Number Publication Date
EP4303492A1 true EP4303492A1 (de) 2024-01-10

Family

ID=82547419

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22183611.7A Pending EP4303492A1 (de) 2022-07-07 2022-07-07 Plattenförmiges rostelement für einen beweglichen rost eines ofens

Country Status (3)

Country Link
EP (1) EP4303492A1 (de)
TW (1) TW202413846A (de)
WO (1) WO2024008930A1 (de)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE338125B (de) * 1968-04-04 1971-08-30 S Alexandersson
US4275706A (en) 1978-07-28 1981-06-30 Warmetechnik Dr. Pauli GmbH & Co. Betriebs KG Air-cooled grate bar
DE3343024A1 (de) 1983-11-28 1985-06-05 Wärmetechnik Dr. Pauli GmbH, 8035 Gauting Luftgekuehlter beweglicher rost
US5033396A (en) 1987-02-18 1991-07-23 Balduin Pauli Grill arrangement, particularly for stepped pivoting grills
EP2487414A1 (de) * 2011-02-04 2012-08-15 Seko-Patent GmbH Roststab
WO2018007854A1 (en) 2016-07-07 2018-01-11 Babcock & Wilcox Vølund A/S Movable grate for a furnace

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE338125B (de) * 1968-04-04 1971-08-30 S Alexandersson
US4275706A (en) 1978-07-28 1981-06-30 Warmetechnik Dr. Pauli GmbH & Co. Betriebs KG Air-cooled grate bar
DE3343024A1 (de) 1983-11-28 1985-06-05 Wärmetechnik Dr. Pauli GmbH, 8035 Gauting Luftgekuehlter beweglicher rost
US5033396A (en) 1987-02-18 1991-07-23 Balduin Pauli Grill arrangement, particularly for stepped pivoting grills
EP2487414A1 (de) * 2011-02-04 2012-08-15 Seko-Patent GmbH Roststab
WO2018007854A1 (en) 2016-07-07 2018-01-11 Babcock & Wilcox Vølund A/S Movable grate for a furnace

Also Published As

Publication number Publication date
WO2024008930A1 (en) 2024-01-11
TW202413846A (zh) 2024-04-01

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