EP0277053B1 - Furnace grate with transversal fire bars which are connected to each other at their front side - Google Patents

Abstract

A hearth grate comprises a succession of transverse bars which are alternately fixed and movable with a reciprocating movement, said bars being formed by disposing in side-by-side relationship at vertical lateral faces elements which are generally rectangular, with a projection portion at the junction of a frontal face and a dorsal face and in the dorsal face blowing orifices opening in said projection portion. The elements are held by the insertion into openings provided in the frontal faces of limbs of a fastener. The fastener comprises a transverse portion which is disposed in set-back relationship with respect to the frontal faces. Plate portions are welded over the openings to retain the fastener.

Description

The invention relates to a hearth grate, for supporting a mass of burning solids, in particular urban waste, comprising, on a downward slope from an upstream loading zone to a downstream ashtray, a succession of transverse bars, alternately fixed and movable back and forth longitudinally, and having on the top a dorsal face to support the mass and a front face in sliding support on the dorsal face of an upstream bar, each bar consisting of a plurality of elements generally rectangular contiguous along vertical side faces.

This type of grid, where the faces of the elements devolved to the thrust are turned upstream, to oppose the rapid descent of combustible solids, and cause mixing of the mass, have been abundantly described in the state of the technique since patent US-A-2,250,067, filed in 1939. Since then, improvements have been made, aimed in particular at the provision of blowing orifices which pass through the elements to bring combustion air to the mass in combustion , from blowing boxes located below the grid.

Patent document FR-A-2 574 160 describes a recoil hearth grid which comprises elements of bars provided, at the connection of the front face and the dorsal face, and on the latter, a transverse faceted projection, with air blowing holes made in a rear facet of the projection, so as to look downstream, and channel air jets from below the grid into the mass of combustible solids, in an upward direction with an angle of about 15 _° on the horizontal.

This patent document further describes means for keeping the elements of adjoining bars in alignment, these means consisting of transverse pins which pass through holes made in the lateral faces at the location of the projections.

In fact, it is essential, for the stability of the combustion settings in particular, that the blowing air reaches the mass in combustion only through the blowing orifices. It is therefore necessary to prevent the rod elements from being lifted by the solids in combustion when they are supported by the lower edge of their front face on the dorsal face of the element located immediately upstream. It will be recalled that the bars are held in place by their weight, and held by the rear end of their lower face on a cross member, which engages in a transverse groove formed in this lower face. The cross member is alternately fixed to the general grid frame, and fixed to a moving frame back and forth.

The purpose of dividing the bars into transversely aligned elements is, on the one hand, to give the bar relative flexibility, and on the other hand to facilitate the assembly and disassembly of the grid by constituting elements of dimensions and manageable weight.

But the counterpart of the fractionation is that the risks of lifting of the elements by the mass in combination are increased; it is therefore recommended to hitch the bar elements together, so that the total weight of the bar opposes the lifting.

The solution recommended by FR-A-2 574 160 has drawbacks, however. The pins can only be inserted into the holes provided for this purpose in the side faces of the elements away from the location of the bar on the grid, because the grid is laterally limited by hearth walls. The bar must be put in place assembled, which involves manipulations of the entire bar. The dismantling in elements also supposes that the bar, removed whole from the grid, is carried away to uncover the elements. This is particularly annoying when it is necessary to dismantle only a few elements, for example to replace them if they appear defective, since it is then necessary to handle all the bars, whole, which comprise at least one defective element.

The patent document EP-A 0 056 139 describes a coupling means for elements of grate bars in which the combustion air is injected into the hearth by passing through gaps made between the lateral edges of neighboring elements. To preserve a relative longitudinal mobility between neighboring elements, useful for removing residues in the intervals provided for blowing, the coupling element is a rectangular hollow profile, with a slot in one face, and the elements have, at the lower part of their side walls, longitudinal edges turned inward, and the coupling element is slid over these longitudinal edges. Such an arrangement is unnecessary for grids according to FR-A 2,574,160. To overcome this drawback, the invention proposes a hearth grate, to support a mass of solid in combustion, in particular urban waste, comprising, in a downward slope of a loading zone upstream to a downstream ashtray, a succession of transverse bars, alternately fixed and movable back and forth longitudinally, and having on the upper side a dorsal face to support the mass, and a front face in sliding support by a lower edge on the dorsal face of an upstream bar, each bar consisting of a plurality of generally rectangular elements in abutment along lateral sides with air blowing channels passing through the elements to open into their dorsal faces, means coupling, arranged near the front faces, ensuring the maintenance in strict transverse alignment of the plurality of elements, characterized in that that said coupling means comprise C-shaped staples with two parallel straight branches joined by a perpendicular cross, each staple being able to be arranged in bridge between two adjoining elements, with each of its branches respectively engaged in an individual housing practiced in the respective front face of one and the other of the joined elements, the section of the housings being adapted to prevent a displacement substantial lateral ment of the respective branches.

It is understood that thus, when mounting the grid, it is only necessary to handle separate elements, the positioning of the staples being done last. In addition, later, to move or replace an element, it suffices to remove the two staples which attach it to the elements placed side by side, or a single staple if it is a border element.

Preferably, the housings are symmetrical with respect to a median plane parallel to the lateral faces, so that the adjacent housings of two contiguous elements are arranged symmetrically with respect to the plane of the contiguous lateral faces.

According to preferred arrangements, the elements include notches which connect the staple branch housings to the adjacent lateral face, to make room for the staple crosspiece. This crosspiece can be engaged in the recesses set back from the front face. The notches can be extended by slits, along the branches. Plates can be welded above the housings to prevent the staple from coming out of the housing, but these platelets must not bridge between the elements, to keep play possibilities.

Preferably, the elements have transverse projections on their dorsal face, at the connection with the front face, with a rear facet where the blowing orifices open out.

• la figure 1 représente, en perspective éclatée, les moyens d'attelage à agrafe selon l'invention ;
• la figure 2 est une coupe suivant le plan II-II de la figure 3 ;
• la figure 3 est une coupe suivant le plan III-III de la figure 2 ;
• la figure 4 est une perspective d'un élément de barreau, dans la zone à l'angle des faces frontale et latérale ;
• la figure 5 est une vue frontale de la zone d'accolement de deux éléments de barreau ;
• la figure 6 est une vue latérale de l'avant d'un élément de barreau, dans le plan VI-VI de la figure 5 ;
• la figure 7 est une vue de dessus d'une grille de foyer selon l'invention.

The characteristics and advantages of the invention will become apparent from the description which follows by way of example, with reference to the accompanying drawings in which:

• Figure 1 shows, in exploded perspective, the clip coupling means according to the invention;
• Figure 2 is a section along the plane II-II of Figure 3;
• Figure 3 is a section along the plane III-III of Figure 2;
• Figure 4 is a perspective of a bar member, in the area at the corner of the front and side faces;
• Figure 5 is a front view of the adjoining area of two bar elements;
• Figure 6 is a side view of the front of a bar member, in the plane VI-VI of Figure 5;
• Figure 7 is a top view of a fireplace grate according to the invention.

The general structure of the hearth grate will be assumed to be known, in particular for burning urban waste, which will be described very succinctly here, referring for details for example FR-A-2 574 160, this document constituting a state of the art close to the present invention.

It will be recalled that this kind of hearth grate comprises, in a downward slope from an upstream loading zone to a downstream ashtray, a succession of transverse bars, alternately movable back and forth longitudinally and having on the upper side of the grate a dorsal face to support the mass, and a front face in sliding support by a lower edge on the dorsal face of an upstream bar. Each bar comprises a plurality of generally rectangular elements placed side by side along vertical lateral faces.

According to the embodiment chosen and shown in Figures 1 to 6, two elements of bars 10 and 11, of which only the regions of interest are shown, are · joined by side faces 109 and 119 respectively. These side faces are vertical on the grid assembled, and perpendicular to a front face 101, 111, respectively, as well as to a dorsal face 102, visible on the element 10 in only FIG. 6. The front faces 101 and 111 comprise two flaps 101 a, 101b for the element 10, and 111 a, 111 b for element 11.

The lower panel is strongly inclined relative to the plane of the dorsal face 102 (see FIG. 6), while the upper panel is inclined at approximately 45 _° on the plane of the dorsal face 102.

The lower panel 101a, 111a. ends, at its lower part, by a rim 100, 110 by which the element 10,11 rests on the dorsal face of the element located immediately upstream.

The dorsal face 102, at its connection with the upper face 101b of the front face, is surmounted by a projection 103 of trapezoidal section, with a front facet 103a in continuity with the upper face 101b, an upper facet 103b substantially parallel to the dorsal face 102, and a rear facet 103c. In this rear facet and perpendicularly to it, blowing orifices 103d are formed.

When the elements are in place on the grid, the orifices 103d are directed downstream, with their axes sloping upward at approximately 15 _° on the horizontal. The blowing orifices 103 are supplied with air by at least one box located below the grid.

As one bar in two is movable back and forth its projection 103 will approach and move away alternately from the projection of the upstream element and that of the downstream element so as to produce a mixing of the solid mass in combustion. The relative inclinations of the front face 101 and the rear facet 103e are such that a block of fuel caught between these surfaces is lifted when they approach.

The orientation of the blowing orifices, slightly inclined to the horizontal, reduces the importance of the fly ash entrained through the boiler tubes.

It is clear that the regularity of combustion depends on the adjustment of the blown air-oxidant, so that it is of primary importance that an element cannot be lifted from its support on the dorsal face of the upstream element.

To link together the elements of the same bar, so that each of the elements is held by the total weight of the bar, the coupling means are used which form the precise object of the present invention.

In each of the front faces 101, 111, and more precisely in the lower sections 101 a, 111 a of these faces are formed near the lateral abutment faces 109, 119 of the housings 104, 114, of rectangular section, which can receive branches 20, 21 of a clip C 2, the two branches 20 and 21 being joined by a crosspiece 22. This clip is of uniform thickness and its branches 20 and 21, as well as its crosspiece 22 have rectangular sections.

The housings 104, 114 are extended, towards the adjoining face 109, 119 by notches 108, 118, such that the crosspiece 22 of the clip 2 can penetrate to come back from the lower face 101a, 111a of the front face 101, 111, while the branches 20 and 21 respectively entering the housings 104 and 114.

It will be understood that the housings 104, 114 are formed perpendicular to the lower panels 101a, 111a of the front faces 101,111 and that the clip 2 is oriented parallel to the lower edges 100,110.

It will be noted that a clearance is provided between the housings 104, 114, the notches 108, 118, and the clip 2 with its branches 20 and 21 and its cross member 22, to allow clearances of the order of a millimeter in all directions. It will be remembered that all of these organs are made of refractory, fragile cast iron.

Furthermore, as seen above in Figures 3 and 6, the notches 108 are extended by slots 105 which extend to the bottom of the housing 104, which provides retaining projections 106 and 107 for the branch of clip (see Figure 4).

This arrangement makes it easier to extract a staple stuck in the housing, by breaking the crosspiece to introduce a hook behind the stuck branch.

It will be understood that the housings 104, 114 and the notches 108, 118 are arranged symmetrically with respect to an abutment plane materialized by the lateral faces 109, 119. Like the elements 10, 11, all have the same structure, in each element , in the vicinity of the lateral faces, there will be two housings 104 and notches 108, arranged symmetrically with respect to a median plane of the element parallel to the lateral faces.

When the clip 2 is in place, two rectangular plates 30, 31 are welded onto the opening of the housings 104 114, so as to trap the clip in its housings. The welding of the wafers is done by performing arc welding points. Because of the fragility of the cast iron, a few chisel blows will blow up the plates 30, 31, to release the clip 2.

It may be advantageous to constitute fiber mats at the bottom of the housings 104 and 114, so that the ends of the branches 20 and 21 are stopped while retaining a possibility of play between the elements 10, 11.

FIG. 7 represents a longitudinal portion of the grid, comprising transverse bars 200, 210, 220, 230, 240, 250, 260, each bar comprising several elements which are referenced with the digits of the tens and hundreds of the bar to which they belong, the number of units being 1, 2, 3 or 4, in order from bottom to top.

The upstream of the grid is on the left of the figure and the downstream on the right.

to avoid the formation of extended longitudinal joint lines, the successive elements are offset laterally by thirds of width. Elements of a third and two thirds of width are arranged at the ends of the bars 210,220,240,250, to achieve this offset.

It will be noted that the element 242 is missing, which reveals the dorsal face of the upstream element 232 in its entire extent.

Note that the bar elements have a projection on the dorsal face at the connection with the front face. The projections are referenced by the reference of the element followed by the letter a. In the rear facet of the projections ... a open blowing orifices referenced by the reference of the element followed by the letter b. To make the figure clearer, the projection references ... a only appear for the bar 200, and only one blowing orifice is referenced per element in the bar 200.

Claims (10)

1. A hearth grate for supporting a mass of combusting solids, in particular urban refuse, comprising, on a downward slope from an upstream loading zone to a downstream ash box, a succession of transverse bars (200, 210, 220, 230, 240, 250, 260) which are alternately fixed and movable with a longitudinal to-and-fro movement and have, on the upper side, a dorsal face (102, 112) for supporting the mass and a frontal face (101, 111) which is slidably supported by way of a lower edge (100, 110) on the dorsal face of an upstream bar, each bar made up of a plurality of generally rectangular elements (10, 11) joined side by side along lateral faces (109, 119) and with air blowing passages (103d, 113d) passing through the elements (10, 11) to issue in their dorsal faces (102, 112), coupling means (2), arranged near the frontal faces (101, 111), ensuring that the plurality of elements are kept in strict transverse alignment, characterized in that the said coupling means comprise C-shaped fasteners (2) having two straight, parallel branches (20, 21) joined together by a perpendicular crosspiece (22), each fastener (2) being capable of being arranged as a bridge between two elements (10, 11) joined side by side and each of the branches (20, 21) of this fastener engaging in an individual housing (104, 114 respectively) made in the respective frontal face (101, 111) of both elements joined side by side (10, 11), the section of the housings (104, 114) being such as to prevent substantial lateral displacement of the respective branches (20,21).

2. A grate in accordance with Claim 1, characterized in that the two housings made in the frontal face (101) of each element (10) with a view to keeping it aligned with similar elements joined either side thereof, are symmetrical in relation to a medial plane parallel to the lateral faces (109).

3. A grate in accordance with one of Claims 1 and 2, characterized in that the bar elements (10, 11) comprise notches (108, 118) linking each of the housings (104, 114) to the neighbouring lateral face (109, 119), these notches (108, 118) being capable of receiving the crosspiece (22) of the fastener (2) bridging two elements (10,11).

4. A grate in accordance with Claim 3, characterized in that the notch (108) is sufficiently deep for the fastener crosspiece (22) to stand back from the frontal face (101, 111) of the elements (10, 11) joined side by side.

5. A grate in accordance with one of Claims 3 and 4, characterized in that a slot (105) extends the notch (108) over the entire depth of the housing (104), the height of this slot (105) being less than the thickness of the branches (20, 21) of the fastener (2).

6. A grate in accordance with any one of Claims 1 to 5, characterized in that the branches (20, 21) and the crosspiece (22) of the fastener (2) have rectangular sections of similar thickness.

7. A grate in accordance with Claim 4, characterized in that small plates (30, 31) are welded in a flat position over the frontal faces (101, 111), each plate at least partially covering a housing (104, 114) of a fastener branch without projecting onto the frontal face of the adjacent element.

8. A grate in accordance with any one of Claims 1 to 7, characterized in that the bar elements (10) have on their dorsal face (102), at the junction with the frontal face (101), at least one transverse projection (103) with a rear, downstream-facing facet where at least one blowing passage (103d) passing through the element opens.

9. A grate in accordance with Claim 8, characterized in that in the grate the blowing passages (103d) have an axis which is directed longitudinally downstream and is ascending, the slope of this axis being closer to the horizontal than the vertical.

10. A grate in accordance with Claim 9, characterized in that the slope of the axis of the blowing passage (103d) is approximately 15_°, the rear facet (103₂) of the projection (103) being perpendicular to this axis.

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