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(11) | EP 0 763 180 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
GRATE FOR A FURNACE, PARTICULARLY AN INFEED GRATE FOR A REFUSE INCINERATOR OFENROST, INSBESONDERE VORSCHUBROST FÜR EINE MÜLLVERBRENNUNGSANLAGE GRILLE POUR UN FOUR, EN PARTICULIER UNE GRILLE D'ALIMENTATION POUR UN INCINERATEUR D'ORDURES |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
TECHNICAL FIELD
[0001] The present invention relates to a grate for a furnace, particularly an infeed grate for a refuse incinerator, said grate being of the kind referred to in the pre-characterizing part of claim 1. Such a grate is known from US-A-4 494 469.
BACKGROUND ART
[0002] In a grate of this kind disclosed in US-A-4,471,704, wherein both sets of grate beams are reciprocatingly movable in opposite phase in their longitudinal direction, the motive mechanism consists of a single shaft disposed beneath the grate beams and transversely to their longitudinal direction, said shaft being restrictedly rotatable back and forth by means of a rack-and-pinion mechanism, the rack of which is reciprocated by a fluid-operated piston-cylinder mechanism and the pinion of which is secured to the shaft. On the shaft below each of the first set of grate beams, pinions are provided engaging with superjacent racks secured to the lower side of each of these grate beams, and below each of the second set of grate beams the shaft has pinions engaging with subjacent racks disposed in a box-like structure secured to the lower side of each of these grate beams. Rack-and-pinion mechanisms are expensive to manufacture and moreover, in the use herein referred to, extremely subject to malfunctions. As there must, necessarily, be a clearance between the sides of the grate surfaces in mutual opposite reciprocation on the adjacent grate beams, ash and slag or unburned particles, e.g. refuse parts, will unavoidably fall down through such clearances and may be deposited on the motive mechanism beneath the grate, especially on the subjacent racks, and thereby impede its functioning and cause wear on it or perhaps even destroy it, this being the more disadvantageous, since this motive mechanism of the known grate is not easily accessible for cleaning, replacement of worn parts or more extensive repairs.
[0003] Applicants' US-A-4,494,469 discloses another grate of the kind referred to for an incinerator, in which only one set of grate beams are reciprocated in their longitudinal direction, whereas the second set of grate beams are stationary. In this known grate, the motive mechanism consists of a single shaft disposed below the grate beams transversely to their longitudinal direction, said shaft via a crank arm being restrictedly rotatable back and forth by a hydraulic piston-cylinder unit. Below each of the reciprocating grate beams, the shaft has radially protruding drivers engaging with recesses in the lower side of these grate beams and on rotation back and forth of the shaft, said drivers implying a reciprocating movement to the beams. This motive mechanism is simple and insensitive to solid combustion products or fuel particles falling down through the clearances between the grate blocks on the stationary and movable grate beams, since the region of engagement between the latter and the drivers lies well protected against such falling through of residues in the lower sides of the grate beams.
[0004] Particularly in the case of infeed grates for incinerators it is in itself desirable that both sets of grate beams are reciprocating in opposite phase, thus achieving a better disintegration and a more uniform distribution over the surface of the grate of the often strongly coherent refuse.
DISCLOSURE OF THE INVENTION
[0005] Therefore, it is an object of the invention to provide a grate of the kind stated in the pre-characterizing part of claim 1 satisfying this desire without having the drawbacks of the known grate referred to previously.
[0006] This object is achieved according to the invention by the features stated in the characterizing part of claim 1.
[0007] Preferably the motive mechanism of the grate is also constructed as stated in claim 2, making it possible to control the quantity conveyed on an infeed grate as well as the disintegration of refuse on such grate.
[0008] It is preferred, particularly in an infeed grate, that the grate is constructed as stated in claim 3, thereby achieving a more reliable removal of fuel and a stronger disintegration and spreading of the refuse, respectively, when the grate blocks on adjacent grate beams in the uppermost area of the grate at the same time rise during their movement towards and away from each other, respectively.
[0009] Used as infeed grate in a refuse incinerator, the grate according to the invention is placed as stated in claim 4.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the following, the invention is explained in more detail with reference to the drawing, in which
Figure 1 is a side view, partly in section, of a grate beam of the first set of grate beams with a number of grate blocks supported on the beams,
Figure 2 in perspective shows a grate block disposed at the end of a grate beam,
Figure 3 in broken sections A and B shows the mechanism for reciprocating movement of a grate beam of the first set and of the second set, respectively, in the longitudinal direction,
Figure 4 is an elevation of the mechanism for restricted rotation back and forth of the first and the second shaft, respectively, and
Figure 5 is a vertical sectional view substantially along the line V-V in Figure 3 through the infeed grate according to the invention between the first and second shaft and showing the drivers secured to the latter engaging in recesses in the lower side of the second set of grate beams.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0011] Figure 1 shows five grate blocks 1 secured to cross members 12 of a grate beam 2 of the first set of grate beams. At its upper end, the grate beam 2 comprises in its lower side a recess 15 adapted to engage with a driver, as will be explained later. As shown, the grate blocks 1 overlap each other, the front part of an upper grate block 1 protruding over the rear part of the succeeding grate block 1 in the row. Each of the grate blocks 1 comprises two substantially horizontal surfaces 4 disposed at a distance from each other and two downwardly inclined surfaces 5, so that the upper side of the row of grate blocks 1 extends like a regular flight of stairs. The surfaces 5 could extend at right angles to the surfaces 4, i.e. substantially vertically. The uppermost grate block 1 comprises a hook-like projection 6 protruding upwardly from the rear part of the upper surface 4, and serving as air seal (cf. Figure 3). The grate beams 3 of the second set of grate beams are constructed in the same manner as the grate beam 2 shown, and the grate blocks 1 are located thereon in the same manner, but the grate beams 3 differ from the grate beam 2 shown in that the engagement recess 18 (Figure 3) in their lower sides are located a distance from the upper end of the grate beams 3, as will be explained later.
[0012] Figure 2 is a perspective view of a grate block 1 placed at the lower end of a grate beam 2 or 3. The grate block 1 consists of two mutually spaced, parallel side members 7 interconnected by means of tie rods 8 on which a number of grate bars 9 are supported, the latter mutually defining passages 10 for air.
[0013] Instead of supporting grate bars 9 with air passages 10 on the tie rods 8, as shown, continuous grate surfaces may be supported on the tie rods, this being particularly preferred as regards grate blocks in infeed grates in refuse incinerators that are located close to the upper ends of the grate beams 2 and 3, whereas the lower grate blocks 1 on the grate beams are constructed as shown in Figure 2 with a view to supplying primary combustion air to the ignited refuse on these grate blocks.
[0014] The grate beams 2 and 3 likewise consist of two parallel, vertical and mutually spaced side stringers 11 rigidly interconnected by means of e.g. welded-on cross members 12 also serving to secure the grate blocks 1.
[0015] In Figure 3, the broken section A shows the motive mechanism making a grate beam 2 of the first set of grate beams reciprocate in its longitudinal direction, whereas the broken section B shows the motive mechanism causing a corresponding reciprocation of a grate beam 3 of the second set of grate beams. In the broken sections A and B, the grate beams 2 and 3, respectively, are shown in the same phase of their movements, viz. in their uppermost positions, but it will be understood that when the grate beam 2 is in the uppermost position shown, the grate beam 3 will be in its opposite, lowermost position.
[0016] In the broken section A, the motive mechanism comprises a shaft 13 capable of limited back-and-forth rotation, on which an outwardly protruding driver 14 is fastened, said driver engaging the recess 15 in the lower side of the grate beam 2 and, when the shaft 13 rotates back and forth, makes the grate beam 2 reciprocate in its longitudinal direction.
[0017] In a similar manner, the motive mechanism shown in the broken section B comprises a shaft 16 capable of limited back-and-forth rotation, on which an outwardly protruding driver 17 is fastened, said driver engaging the recess 18 in the lower side of the grate beam 3 and, when the shaft 16 rotates back and forth, reciprocates the grate beam 3 in its longitudinal direction. The shafts 13 and 16 rotate back and forth in opposite phase. This does not appear from Figure 3, in which the grate beams 2 and 3, as mentioned, are shown in the same phase of their movement.
[0018] Another important feature to be mentioned is the fact that, when the shaft 13 rotates clockwise from its extreme position shown in the broken section A into its opposite extreme position, the part of the driver 14 engaging the recess 15 will pass through a circular arc, and so will the recess 15 and with it the uppermost end of the grate beam 2. Thus, for each reciprocation of the grate beam 2, its uppermost end will in the same manner carry out an up-and-down movement transversely to the longitudinal extent of the grate beam 2, whereas its lowermost end, i.e. the right-hand end in Figure 1, undergoes a purely translatory motion. Thus, during each of its reciprocating movements, the grate beam 2 will carry out a rocking movement about its lowermost end. With reference to the broken section B, exactly the same applies to the grate beam 3, i.e. for each reciprocating movement it will carry out a rocking movement about its lowermost end. These rocking movements of the grate beams 2 and 3 taking place simultaneously for the grate beams 2 and 3 being reciprocated in counter-phase partly facilitate the discharge of refuse from a chute placed above the uppermost part of the infeed grate, partly contribute to the disintegration and spreading of the refuse having been discharged.
[0019] Figure 4 shows the motive mechanism for limited back-and-forth rotation of the shafts 13 and 16. This motive mechanism comprises a fluid-driven, preferably hydraulically driven, piston-cylinder unit 19, the cylinder of which as shown at 20 is pivotably secured to a bracket 21 mounted on the lower structure of the infeed grate, and the piston rod of which, as shown at 22, is linked at its end to one arm of a two-armed lever 23 being secured to a protruding end of the shaft 13. The other arm of the two-armed lever 23 is as shown at 24 linked to one end of a link rod 25. The other end of the link rod 25 is, as shown at 26, linked to a one-armed lever 27 secured to a protruding end of the shaft 16.
[0020] Reciprocation of the piston rod in the piston-cylinder unit 19 will cause a back-and-forth rotation of the two-armed lever 23 and hence also the shaft 13, as the back-and-forth rotation of the lever 23 via the link rod 25 at the same time causes an opposing back-and-forth rotation of the one-armed lever 27 and consequently of the shaft 16. These rotating movements are naturally restricted by the length of stroke of the piston-cylinder unit 19, said length of stroke as well as the extent of the stroke and its frequency preferably being adjustable in a manner well-known to the skilled person.
[0021] Finally, Figure 5 is a vertical sectional view, mainly along the line V-V in Figure 3, through the infeed grate according to the invention and showing grate blocks 1 secured to the grate beams 2 and 3 and the shaft 16 being rotated back and forth by the one-armed lever 27 and being equipped with the upwardly protruding drivers 17 engaging the recesses in the lower sides of the grate beams 3. Reference numeral 28 designates walls in the combustion furnace (not shown) of the incinerator, while 29 indicates the lower structure (not shown) of the infeed grate according to the invention.
[0022] It will be understood that above the infeed grate according to the invention and approximately above a section of it corresponding to the horizontal extent of the broken section A in Figure 3 there is, as previously mentioned, a chute or receiving hopper for refuse to be incinerated, and from where the refuse is removed by means of the uppermost grate blocks 1 on the grate beams 2 and 3.
[0023] In the above description, the infeed grate according to the invention is solely mentioned in connection with infeed of refuse in an incinerator, but as will be evident, it can equally well be used for infeeding other fuels, such as e.g. solid fossil fuels or a mixture of refuse and solid fossil fuel in the incinerator, if the latter's operating conditions make this desirable or necessary. Also other types of fuel, e.g. wood chippings, can be feed into the incinerator, either alone or together with refuse by means of the infeed grate according to the invention.
[0024] Likewise, it will be evident that even though the grate according to the invention has been described in the preceding detailed description as being an infeed grate for introducing fuel into an incinerator, grates according to the invention, possibly modified in an appropriate manner, can be used as downstream grate sections in an incinerator of the type, in which only advancing and rearranging of the fuel on the grates take place.
a) that a first (13) and a second (16) shaft capable of limited back-and-forth rotation extending transversely to the longitudinal direction of the grate beams (2,3) and having engagement means engaging complementary engagement means at the lower sides of the reciprocatable grate beams, are placed with their axes spaced from each other,
b) that radially protruding drivers (14) on the first shaft (13) in a per se known manner engage with at least one recess (15) in the lower side of each grate beam (2) of the first set,
c) that radially protruding drivers (17) on the second shaft (16) similarly engage with at least one recess (18) in the lower side of each grate beam (3) of the second set, and
d) that the first (13) and the second (16) shafts are adapted to be rotated back and forth in opposite phase by a mechanism, in which one arm of a two-armed lever (23) fixed to the first shaft (13) is rotatably connected to a piston rod in a pivotably supported fluid-operated piston-cylinder unit (19), the other arm of said two-armed lever (23) being linked to a one-armed lever (27) secured to the second shaft (16), whereby the first set of grate beams (2) and the second set of grate beams (3) can be reciprocated in opposite phase in the longitudinal direction of the grate beams (2,3).
dadurch gekennzeichnet, daß
a) eine erste (13) und eine zweite (16) Welle, die eine begrenzte Hin- und Herdrehung ausführen können, sich quer zur Längsrichtung der Rostträger (2, 3) erstrecken und eine Eingriffseinrichtung aufweisen, die in eine komplementäre Eingriffseinrichtung an den unteren Seiten der hin- und herbewegbaren Rostträger eingreift, mit ihren Achsen voneinander beabstandet eingesetzt sind,
b) radial vorstehende Antreiber (14) auf der ersten Welle (13) in einer an sich bekannten Weise in Eingriff treten mit zumindest einer Aussparung (15) in der unteren Seite jedes Rostträgers (2) des ersten Satzes;
c) radial vorstehende Antreiber (17) auf der zweiten Welle (16) in ähnlicher Weise in Eingriff treten mit, zumindest einer Aussparung (18) in der unteren Seite jedes Rostträgers (3) des zweiten Satzes; und
d) die ersten (13) und die zweiten (16) Wellen dazu angepaßt sind, in entgegengesetzter Phase durch einen Mechanismus hin- und hergedreht zu werden, bei dem ein Arm eines zweiarmigen Hebels (23), der an der ersten Welle (13) befestigt ist, drehbar mit einer Kolbenstange in einer schwenkbar gehaltenen, fluidbetätigten Kolben-Zylinder-Einheit (19) verbunden ist und der andere Arm des zweiarmigen Hebels (23) mit einem einarmigen Hebel (27) verbunden ist, der an der zweiten Welle (16) befestigt ist, wobei der erste Satz von Rostträgern (2) und der zweite Satz von Rostträgern (3) in entgegengesetzter Phase in der Längsrichtung der Rostträger (2, 3) hin- und herbewegt werden können.
dadurch gekennzeichnet, daß
die Hublänge, der Hubbereich und die Hubfrequenz der fluidbetätigten Kolben-Zylinder-Einheit (19) individuell einstellbar sind.
dadurch gekennzeichnet, daß
die Aussparung (15) in der unteren Seite jedes des ersten Satzes von Rostträgern (2) in unmittelbarer Nähe zu dem am weitesten oben gelegenen Ende der Rostträger angeordnet sind, und daß die Aussparungen (18) in der unteren Seite jedes des zweiten Satzes von Rostträgern (3) in einem größeren Abstand als der Abstand zwischen den Aussparungen (15) im ersten Satz von Rostträgern (2) und dem am weitesten oben gelegenen Ende der Rostträger von den am weitesten oben gelegenen Enden der Rostträger entsprechend dem Abstand zwischen den Achsen der ersten und der zweiten Wellen (13, 16) gesetzt sind, so daß die am weitesten oben gelegenen Enden der Rostträger (2, 3) für jede hin- und hergehende Bewegung der Träger eine nach oben gerichtete und nach unten gerichtete Bewegung quer zur Längsrichtung der Rostträger (2, 3) ausführen.
a) un premier (13) et un second (16) arbres capables de tourner de façon limitée avec un mouvement de va-et-vient et s'étendant transversalement à la direction longitudinale des montants de grille (2, 3) et possédant des moyens de coopération coopérant avec des moyens de coopération complémentaires au niveau des côtés inférieurs des montants de grille pouvant avoir un mouvement de va-et-vient, sont disposés avec leurs axes à une certaine distance l'un de l'autre,
b) des organes entraîneurs faisant saillie radialement (14) sur le premier arbre (13) d'une manière connue en soi coopèrent avec au moins un évidement (15) situé dans le côté inférieur de chaque montant de grille (2) du premier jeu,
c) des organes entraîneurs faisant saillie radialement (17) sur le second arbre (16) coopèrent d'une façon similaire avec au moins un évidement (18) situé dans le côté inférieur de chaque montant de grille (3) du second jeu, et
d) les premier (13) et second (16) arbres sont susceptibles d'être tournés avec un mouvement de va-et-vient en opposition de phase par un mécanisme, dans lequel un bras d'un levier à deux bras (23) fixé au premier arbre (13) est relié de façon mobile en rotation à une tige de piston dans une unité piston-cylindre (19) commandée par fluide supportée de façon pivotante, l'autre bras dudit levier à deux bras (23) étant relié à un levier à un bras (27) fixé au second arbre (16), ce par quoi le premier jeu de montants de grille (2) et le second jeu de montants de grille (3) peuvent être déplacés avec un mouvement de va-et-vient en opposition de phase dans la direction longitudinale des montants de grille (2, 3).