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(11) | EP 1 840 463 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Combustion grate spanning system |
| (57) Spanning system for an incineration or combustion grate in an incineration or combustion
plant, said grate comprising a number of juxtaposed grate beams, at least some of
which are movable for providing a movement of the fuel on top of said grate. The spanning
system comprises - a number of spanning units positioned under the grate, each spanning unit comprising - two engagement means, each for engaging a grate beam, and - force-generating means for providing a stable force pulling the engagement means towards each other, whereby the grate beams between the two engagement means are pulled towards each other. This provides the possibility of a modular system and keeps the necessary forces small. |
TECHNICAL FIELD
[0001] The present invention relates to a spanning system for an incineration or combustion grate in an incineration or combustion plant. Such grates typically comprise a number of juxtaposed grate beams, of which at least some are movable for providing a movement of the fuel on top of the grate.
BACKGROUND ART
[0002] In incineration and combustion plants of this kind it is known to have some of the grates movable in the transport direction of the fuel on top of the grates and to secure an intimate contact between adjacent grate beams by using hydraulic cylinders positioned along the sides of the grate, said hydraulic cylinders pressing all the grate beams of the grate towards each other. With larger grates, the forces of this system increase and the necessary play for possible expansion increases leading to possible ingress of particles between the grate beams resulting in wear on the sides of these.
DISCLOSURE OF THE INVENTION
[0003] It is the object of the present invention to provide a spanning system, which is of a simple construction and which provides a stable force keeping the grate beams together under varying temperature conditions, and this is achieved by a spanning system as indicated in claim 1. With this arrangement, the spanning together of the grate beams in a grate can be provided in a modular fashion, each spanning unit spanning over a small number of beams, e.g. maximum six beams, and thus the necessary forces for keeping these beams together are relatively small compared to the forces necessary to keep all of the beams in the grate together by the known hydraulic system. Furthermore, the force-generating means provide the necessary play for possible expansion without providing any possibilities for particles to penetrate in between the individual grate beams.
[0004] Preferred embodiments of the spanning system, the advantages of which will be evident for a man skilled in the art after reading the following detailed description, are indicated in the sub-ordinate claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] In the following detailed part of the present description, the invention will be explained in more detail with reference to the exemplary embodiments of a spanning system according to the invention shown in the drawings, in which
Figure 1 schematically shows a cross-section in a combustion grate, in which a spanning system in accordance with a preferred embodiment of the present invention is provided,
Figure 2 schematically shows a cross-section in the longitudinal direction of the grate in Fig. 1,
Figure 3 schematically shows details of a spanning unit in accordance with a preferred embodiment of the present invention, and
Figures 4-15 schematically show other possible embodiments in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0006] The combustion grate shown in cross-section in Fig. 1 comprises a number of grate beams 1 extending in the moving direction of the fuel on top of the grate and arranged to be alternating movable 1' and stationary 1 grate beams in the crosswise direction. The spanning unit 2 comprises two mainly vertical main bars 3, 4, which at the upper ends are provided with engagement means for engaging the stationary grate beams 1. A first distance bar 5 is connected between the main bars 3, 4, said distance bar 5 being provided with a screw thread and nuts 8 in order to be able to adjust the distance between the two main bars 3, 4 at the lower end of these. At an intermediate position between the first distance bar and the engagement means, a second distance bar 6 is connected between the two main bars 3, 4, said connection between the second distance bars 6 and the two main bars 3, 4 comprising spring means 7, preferably in the form of Belleville springs positioned inside a tube fixedly connected to the main bars 3, 4. Thus, the distance bar 6 functions as a pulling bar pulling the two main bars 3, 4 towards each other, whereby the engagement means connected to the stationary grate beams 1 pulls these towards each other, thus keeping the grate bars 1, 1' between the two engagement means in intimate contact along their side surfaces.
[0007] The connections between the distance bars 5, 6 and the main bars 3, 4 allow a certain tilting movement of the main bars 3, 4, whereby the spanning unit 2 can be mounted under the grate by loosening the nuts 8 and increasing the distance between the engagement means, whereby these can be put into engagement with the stationary grates 1, whereafter the nuts 8 are tightened until a certain pre-spanning of the spring means 7 is achieved. As an alternative, the mounting may be eased by providing one of the distance bars in a two part form assembled after engagement with the grate beams.
[0008] As shown in Fig. 1, the spanning unit 2 can be provided in different sizes shown as 2', the spanning unit 2' having the same function and same components as the spanning unit 2, but provided with shorter distance bars 5', 6', whereby the spanning unit 2' spans over a minor number of grate beams 1. In order to protect the screw thread on the distance bar 5, 5' against grate screenings falling through the grate, a covering plate 9 is provided on the main bars 3, 4 covering at least the normally used part of the screw thread on said distance bar 5, 5' during use. A similar covering plate (not shown) may be provided to protect the distance bar 6, 6'.
[0009] As shown in Fig. 2, two spanning units 2 are provided, one at each end of a grate beam 1, in order to distribute the forces pressing the grate beams towards one another. If considered necessary, more than two such spanning units can be used for each set of grate beams being spanned together by the spanning system.
[0010] Furthermore, Fig. 2 schematically shows the moving mechanism for moving the movable grate beams, comprising a rocking beam 10 and a roller 11, only shown schematically, and also shows tubing 12 for circulating cooling water in a water-cooled grate.
[0011] Figure 3 shows a main beam 3 and details regarding the engagement means, which comprises a tap 13 for engaging a hole provided in the grate beam for keeping the main bar 3 in position relative to said grate beam, and further comprising an engagement surface 14 for transferring the spanning forces to the grate beam.
[0012] Fig. 3 also shows details regarding the connection between the distance bar 6 and the main bar 3 in the form of a tube 15 in which Belleville spring discs are positioned around the distance bar 6 and compressed between a nut on the distance bar 6 and a bottom plate 16 of said tube 15, said bottom plate 16 being provided with a hole through which the distance bar 6 extends.
[0013] In an alternative embodiment, as shown schematically in Fig. 4, the spanning unit is provided in the form of a U-profile, one leg of the U-profile comprising engagement means for directly engaging a grate beam and the other leg of the U-profile being provided with spring means for engaging the grate beam. As shown in Fig. 5, this embodiment may be supplemented by an adjustment screw for adjusting the distance and/or force transferred to the grate beams.
[0014] In the alternative embodiment shown in Fig. 6, the spanning unit is formed of spring steel elements mutually connected at one end and formed into a Y-form, where each of the elements is provided with engagement means for engaging the grate beams. Supplementary this construction can, as shown in Fig. 7, be provided with an adjustment screw between one or both of the legs of the spanning unit for adjusting the distance and/or force between the two engagement means.
[0015] Figures 8 and 9 schematically show an embodiment, in which the rods comprising engagement means are mutually connected by a pivot and the force for pressing the engagement means towards one another is provided by means of a spring between the two rods opposite the pivot relative to the engagement means. Fig. 8 shows the possibility of compressing the spring in order to mount the spanning unit onto the grate beams, and Fig. 9 indicates the possibility of having an adjustable force transferred from the spring to the engagement means.
[0016] The figures 10 and 11 schematically show corresponding tongue-like constructions, where Fig. 10 provides force by means of a load hanging on one arm of the tongue opposite the pivot mutually connecting the engagement means, and Fig. 11 provides the force by means of a spring connected between the two arms of the tongue and further comprising adjustment means for adjusting the distance and/or force between the two engagement means.
[0017] The figures 12 and 14 show alternative embodiments, in which the force for pulling the engagement means towards each other is provided by means of a load connected by a wire to one of the engagement means, said wire running over a pulley connected to the other engagement means. The difference between Fig. 12 and Fig. 14 lies primarily in the possibility of positioning the pulley and the wire under the grate beams in Fig. 12, and the pulley and wire being inserted through the grate beams being pressed together by the spanning unit and the wire being directly connected to one of the engaged grate beams and connected to the other of the engaged grate beams by the pulley being connected thereto in Fig. 14.
[0018] Figure 13 shows an embodiment, in which a pulling spring is connected between two engagement means engaging the grate beams, and
1. Spanning system for an incineration or combustion grate in an incineration or combustion
plant, said grate comprising a number of juxtaposed grate beams, at least some of
which are movable for providing a movement of the fuel on top of said grate, said
spanning system comprising
- a number of spanning units positioned under the grate, each spanning unit comprising
- two engagement means, each for engaging a grate beam, and
- force-generating means for providing a stable force pulling the engagement means towards each other, whereby the grate beams between the two engagement means are pulled towards each other.
2. Spanning system in accordance with claim 1, characterised by further comprising adjustment means for adjusting the distance and/or force between
the two engagement means.
3. Spanning system in accordance with claim 1 or 2, characterised by the engagement means comprising an engagement surface and an engagement tap keeping
the engagement means in a fixed position relative to the engaged grate beams.
4. Spanning system in accordance with claim 1, 2 or 3, characterised by the engagement means engaging stationary grate beams and at least one grate beam
being positioned between the two stationary grate beams engaged by the two engagement
means of each spanning unit.
5. Spanning system in accordance with any of the preceding claims, characterised by the adjustment means comprising a screw engaging a nut for adjusting the distance
and/or force between the engagement means.
6. Spanning system in accordance with any of the preceding claims, characterised by each spanning unit comprising
- two main bars having the engagement means at one end thereof and
- a first and a second distance bar connected between the main bars at different distances from the engagement means, the first distance bar comprising adjustment means for adjusting the distance between the main bars and thus the distance between the engagement means, the second distance bar providing a mainly fixed distance between the two main bars.
7. Spanning system in accordance with claim 6, characterised by the force-generating means being provided by the main bars being made of spring steel.
8. Spanning system in accordance with claim 6, characterised by the force-generating means being provided by the second distance bar being connected
to the main bars through at least one spring.
9. Spanning system in accordance with any of the preceding claims 6-8, characterised by the adjustable distance bar being positioned at the end of the two main bars opposite
the engagement means.
10. Spanning system in accordance with any of the claims 6-9, characterised by the mutual distances between the engagement means, the first distance bar and the
second distance bar being approximately equal.