EP0399898B1 - Roll for a furnace roller grate, especially for burning waste, with a tubular lining formed by annular grate bars separated between them by air gaps of constant width - Google Patents

Abstract

The grate roll, of conventional structure, has a framework in the form of a cylindrical cage with longitudinal members (10) with a T- shaped profile arranged according to generating lines, and a lining formed from groups (G) of rings separated by gaps (i) for blowing oxidant air, the rings being segmented into bars ((1-6).11, (1-6).11') in the form of arcs which extend between the longitudinal members. According to the invention, in order to limit the clearance of the bars while leaving them play, they are, attached on one side by an indentation to the wing of a longitudinal member, held in position by bosses ((1-6).128, (1-6).129) of an interposed piece (12) bolted longitudinally onto the longitudinal member; the bars ((1-5).11, (1- 5).11') have recesses at their end which is contiguous with the intermediate piece (12), in which the bosses engage. The bars are thus attached with limited clearance in the axial, radial and peripheral directions in relation to the roll. <IMAGE>

Description

The invention relates to a roll of hearth grate intended in particular for the incineration of waste and comprising a cascade of rollers driven in rotation about parallel horizontal axes, this roll comprising a framework in a cylindrical cage with, between two flanges, longitudinal members arranged along generators regularly distributed over the periphery, and a tubular lining formed of a plurality of groups of circular rings generally in planes perpendicular to the axis, in axial succession from one flange to the other, intervals being provided between the rings for supplying combustion air, while the rings are segmented into arcuate bars which hang, with play, between two neighboring side members, and intermediate pieces associated respectively with the groups of rings and fixed to the stringers so as to limit the axial travel of the bars in the groups.

The hearth grates formed of a cascade of rollers are suitable for the incineration of solid waste, household waste or industrial residues which have an erratic texture, a high moisture content and a relatively low calorific value, because they cause displacement, backfilling and reversing of the combustible layers which descend the cascade, and lend themselves to a distributed blowing of oxidizing air at high flow rate, conducive to the drying of the waste at the entry into the furnace and to the acceleration of combustion.

Documents FR-A-1 286 528 and EP-A-0 124 826 generally describe a roller grille of this kind.

As in all hearth grates, the elements on which the combustible materials rest are subjected to very severe thermal stresses, between overheating due to radiation and contact with materials in combustion, and cooling from the supply of combustion air. The rollers therefore have a lining of refractory castings, mounted with clearance on a load-bearing framework. The design of the lining of rotary grate rollers poses particular problems, the lining being subjected to thermal cycles with heating in the hearth, for almost half a turn, and cooling below the hearth for the rest of the turn. Furthermore, the packing elements, at the same time as they are rotated by the roller, perform a rotation on themselves relative to the vertical direction of gravity. Their attachment to the framework must hold them in the three directions perpendicular, radial peripheral or tangential, and axial.

The framework very generally has a cylindrical cage structure (DE-C-1 164 014; DE-C-3 341 835; EP-A-0 124 826) with, between two end flanges, iron longitudinal members T arranged along generatrices of the cage with regular angular spacing, the core of the side members being oriented in a plane passing through the axis of the roller, and directed towards this axis.

The packing elements are commonly bars in the form of ring segments, which each extend between two neighboring side members, and follow one another along the periphery of the roller to form a ring in a plane perpendicular to the axis of the roller. The rings follow one another from one flange to the other and an interval for the supply of combustion air is provided between two successive rings, generally thanks to the presence of projecting keys on the lateral flanks of the bars. In contact, the keys of two axially contiguous bars therefore determine the minimum width of the interval.

According to the documents mentioned above, the bars have a section, perpendicular to the periphery of the ring, T-shaped with a web forming a rib directed towards the axis, in a plane perpendicular to this axis, while the wings form the support surface for the combustible mass. The attachment of the bars is obtained by providing notches at the two ends of the core which engage around the wings of the side members. To put the bars in place, at least one flange is released and the bars are threaded parallel to the axis. Note, however, that the first bars can be presented at an angle with a plane perpendicular to the axis between the side members, so that the core of the bar, below the notches, passes between the wings of the side members. Then we return the bar to its normal orientation.

The need to provide differential expansion gaps between the bar and the frame, the possible wear of the range keys, and the trapping of debris from the combustible mass between the bars can lead to substantial variations in the actual width of the intervals between bars, on the axial extent of the roller, especially if this extent is large. The distribution of the combustion air in the combustible mass is then disturbed.

According to document EP-A-0 124 826, this drawback is attenuated, while disassembly of the roller is facilitated, by dividing the rings into a plurality of groups, and by placing intermediate rings between the groups. These intermediate rings are formed of parts in a ring segment, with a first end bolted to a spar, while the second end rests on the spar immediately behind. This second end is extended by a tenon, which a mortise made in the first end of the contiguous intermediate piece behind traps. The spacers have at least one row of blow holes.

It is understood that, in place, these intermediate pieces limit the axial play of the group of rings with which they are associated by neighborhood, and that, removed, they allow a biasing of the bars sufficient to allow disassembly without touching the flanges.

However, this arrangement is not fully satisfactory, the games in a group may still be cumulative. The blowing orifices provided in the intermediate pieces are liable to become blocked more easily than the intervals between bars, their walls having no relative mobility. Finally, the intermediate pieces are long and locked in overhang by one end forming an arc between two beams, which makes them fragile, especially since they are necessarily subjected to thermal and mechanical cyclic and asymmetrical stresses.

Also, to remedy these drawbacks, the invention provides a roll of hearth grate intended in particular for the incineration of waste and comprising a cascade of rollers driven in rotation about parallel horizontal axes, this roll comprising a framework in a cylindrical cage with, between two flanges, longitudinal members arranged according to generators regularly distributed over the periphery, and a tubular lining formed by a plurality of groups of circular rings generally in planes perpendicular to the axis, in axial succession of a flange at the other, intervals are provided between the rings for blowing combustion air, while the rings are segmented into arcuate bars which hang, with play, between two neighboring side members, and intermediate parts, associated respectively with groups of rings, and fixed to the side members so as to limit the axial travel of the bars in the groups, charac terized in that each intermediate piece is fixed longitudinally on a spar over the axial extent of a group of rings, between contiguous ends of bars, this intermediate piece and the contiguous ends of bars having respectively complementary interlocking conformations able to limit the travel of these bar ends in axial, radial and peripheral directions.

The spacers are mounted longitudinally without overhang on the side rails, and are thus protected against thermal stresses or mechanical shocks. The interlocking conformations ensure that each end of the bar contiguous to the intermediate piece is maintained in an average position relative to the framework, so that the variations in width of intervals between rings are not cumulative, and that the distribution of combustion air remains suitable.

Preferably, the side members are even in number with a current T profile. The bars then have the respective nesting conformation at a first end, and at the second end a notch in a core, which engages on a spar wing; for each group of rings, there is one insert per pair of side members.

In a preferred arrangement, then, the intermediate pieces associated with the successive groups are alternately mounted on one and the other side members of a pair.

The intermediate pieces are preferably of generally parallelepipedal shape with two lateral faces substantially parallel to the core of the spar, and external and internal faces parallel to the wings, the interlocking configuration being, for the intermediate piece, constituted by bosses protruding from the side faces and narrowing from the outside face until it merges into the side walls, these bosses repeating in direction parallel to the axis with a pitch corresponding to the width of a ring increased by that of a blowing interval.

These bosses preferably marry portions of spheres. The first ends of the bars have complementary recesses located at the angles of the wings of the T-section bar with the first end. The intermediate bosses of the intermediate piece each occupy the contiguous recesses of two bars. At the corners of the insert, the bosses are half of the intermediate bosses.

According to a preferred arrangement, the intermediate piece is in two radially superimposable parts; a parallelepiped base is fixed directly on the beam and facilitates, during assembly, the positioning of the bars; then a crown is reported which carries the interlocking bosses.

• la figure 1 représente schématiquement une grille de foyer formée d'une cascade de rouleaux ;
• la figure 2 représente, en section partielle, l'agencement d'un garnissage de rouleau selon l'invention ;
• la figure 3 représente, en développé, une partie du garnissage selon l'invention, avec une pièce intercalaire ;
• la figure 4 est une vue en perspective d'un barreau de grille ;
• la figure 5 est une vue en perspective d'une pièce intercalaire ;
• la figure 6 représente, en développé partiel, un agencement de garnissage selon l'invention.

Additional characteristics and advantages of the invention will emerge from the description which follows by way of example, with reference to the appended drawings in which:

• FIG. 1 schematically represents a hearth grid formed by a cascade of rollers;
• 2 shows, in partial section, the arrangement of a roller lining according to the invention;
• Figure 3 shows, in the developed, part of the lining according to the invention, with an intermediate piece;
• Figure 4 is a perspective view of a grid bar;
• Figure 5 is a perspective view of an insert;
• FIG. 6 shows, in partial development, a packing arrangement according to the invention.

As shown in Figure 1, a roller hearth grid consists of a plurality of rollers 1, 2, 3, 4 which follow one another on a downward slope, with their axes 1b , 2b ; 3 b , 4 b parallel and generally equidistant, and which rotate around their axes in a direction (here clockwise) such that the part of their periphery 1 a , 2 a , 3 a , 4 a which is on the top goes in the direction of the downward slope. The waterfall has been represented here with four rollers, so as not to overload the figure. In practice, waterfalls frequently have five or six rollers. The grid thus forms a cascade, the solid fuel, such as urban waste, being discharged on top of the roll 1, while the ashes and bottom ash will be discharged by the lower roller 4 towards an ashtray.

For combustion maintenance, combustion air is blown either laterally or from below to be injected into the combustible mass through interstices in the periphery 1 a , 2 a , 3 a , 4 a rollers. To support the combustible mass and allow the combustion air to pass, the periphery of the rollers, as shown diagrammatically on the roll 1 of FIG. 1, is coated with a refractory metal lining, consisting of a succession of rings separated by intervals i (see figure 3), from one flange 1 c , 2 c , 3 c , 4 c from the roller to the other (not visible and not referenced). The structure and shape of the flanges are conventional, and are not specified here.

Since the lining is subjected to temperature cycles, with heating in contact with the combustible mass, and cooling during the part of revolution between the unloading on the lower roller and the unloading of the upper roller, the rings are attached, with clearance, to the roller support structure. This play exists in three dimensions, axial, radial and peripheral of the roller.

To minimize axial slippage of the rings as a whole, with more or less complete obliteration of certain intervals i, while others widen, which would cause annoying irregularities in the distribution of combustion air, these rings are divided into groups G1, G2, G3, associated intermediate pieces limiting the axial sliding of the group of rings. The groups of rings have been represented three in number, so that the figure is sufficiently detailed without being overloaded; of course this number of three is not imperative.

The rings are themselves divided, along the periphery, into arcuate bars which are hooked by their ends, to structural beams, which form a cylindrical cage extending from a flange 1 c , 2 c , 3 c , 4 tsp roll to another. According to a widespread state of the art, these longitudinal members are T-sections, with a core in a plane passing through the axis of the roller and directed towards this axis, and wings aligned in a plane tangent to the periphery of the cage. In FIG. 2, which takes up the widespread state of the art on this point, these longitudinal members, seen in section, are designated by the references 10, 10 ′, 10 ″, 10 ‴.

According to document EP-A-0 124 826, the bars have a T-section, with wings defining the external surface of the lining, and a core directed towards the axis of the roller and disposed in a plane perpendicular to this axis. Notches in the core at the two ends of the bar are engaged around the wings of two neighboring side members. The spacers, which maintain the independence of the groups of bars, are ring arcs which are bolted at one end to the wing of a spar, and rest on the neighboring spar by their other end.

It will be noted that, in this arrangement, the mounting of the bars is carried out, before fitting of the intermediate rings, either by threading them on the side members from the location of a flange (dismantled), or by introducing them from bias between the side members.

This arrangement of the state of the art has been described in relatively detail, the present invention having for its object to improve this prior arrangement, by overcoming certain disadvantages which it presents.

A first drawback comes from the fact that the intervals between bars, which are maintained above a minimum value by lateral abutment spans, see the games being distributed erratically within a group; it can happen that all the games of the group accumulate on a particular interval, where the passage of combustion air will be favored. In addition, the intermediate parts fixed in overhang by the bolting of one end, can break by the actions more or less combined fuel load and asymmetric heating.

According to the arrangement chosen and represented in FIGS. 2 and 3, the longitudinal members 10, 10 ', 10' ', 10 ‴ are found in even number on the periphery of the structural cage (here the longitudinal members have an angular spacing of 45 °). Bars 11, 11 ', 11' ', 11 ‴ ... in peripheral sequence (Figure 2) and 1.11, 1.11'; 2.11, 2.11 '; 3.11, 3.11 '; 4.11; 4.11 '; 5.11, 5.11 ', in axial sequence in group G, are held at a first end 112 by an intermediate piece 12, bolted longitudinally to the beam 10', and hung at their other end 115 by the engagement of a notch 116 on a wing of the spar 10, in an arrangement similar to that of the state of the art. We see that the bars 11, 11 ', 11' ', 11 ‴ ... follow one another along the periphery of the ring, in alternately inverted positions, so that the bars are joined in the ring, either by their second end 115, or by their first end 112, on either side of the intermediate piece 12.

As best seen in FIG. 4, the bar has, between the regions of its first 112 and second 115 ends, a T-section, with an outer face 110, which follows the lining cylinder and forms the wings of the T, and a core 111 which forms a rib, in the general plane of the ring of which the bar 11 forms a part, perpendicular to the axis of the roller.

The first end 112 of the bar 11 is shaped on the end face in a plane parallel to the plane of the core of the spar, and is continued by a bearing face 112 a , capable of laying flat on the wing of the spar 10 ' (figure 2). At the two angles of the outer 110 and terminal 112 faces of the first end, quarter-hemisphere recesses 114 and 114 ′ are provided, the hemisphere center being located substantially at the aforementioned virtual angle. Below the bearing face 112 a is an engagement bevel 113, which is connected with the bearing face 112 by a flange made to abut on the edge of the spar wing.

The second end 115 is shaped on the end face, which overhangs the hooking notch 116.

The insertion of the bar 11 between the pair of beams 10, 10 ′ is carried out by presenting the notch 116 of the second end 115 of the bar on the wing of the beam 10, then by placing the bearing face 112 a on the wing of the spar 10 ', then by fitting the intermediate piece 12, as will be explained after the description of this piece.

As shown in FIG. 5, the intermediate piece has a generally parallelepiped shape with an outer face 120, which will come close to the packing cylinder, an inner face 121 intended to lie flat on the spar, outside and inside being heard relative to the roller. grid, two lateral faces 121 and 122, corresponding to the end faces of the first bar end, and end faces 124 and 125. Two holes 126 and 126 ', perpendicular to the external face 120, provided for the passage of fixing bolts of the insert 12 on the beam 10 ', open into this outer face by square housings for the bolt heads.

Projecting from the side faces 122 and 123, twelve bosses respectively 1.128, 2.128, 3.128, 4.128, 5.128, 6.128 and 1.129, 2.129, 3.129, 4.129, 5.129, 6.129 or, for short, (1-6) .128, (1 -6) .129 leave flush with the outer face 120 to go narrowing until it merges into the respective lateral face.

It can be understood from FIG. 2 that the bosses are complementary to the recesses 114 and 114 'in the terminal face of the first end of the bar 112. The intermediate bosses (2-5) .128, (2-5) .129 have the form of halves of hemispheres, while the end bosses 1.128, 6.128, 1.129, 6.129 have the shape of quarters of hemispheres. The centers of the hemispheres are located on the (virtual) edges between the upper face 120 and faces lateral 122 and 123, and follow one another longitudinally with a pitch equal to a width of bar 12 (taken parallel to the axis of the roll) increased by the width of an interval i.

It is easily understood that the intermediate piece 12 determines, apart from the axial position of the first ends of the bars, relative to the spar. It is no longer possible for games to accumulate over an interval. It limits the travel of the bars 11 in the axial, radial and peripheral directions.

It will be noted that the intermediate piece 12 consists of two superposed elements, a base 127 which will rest on the spar 10 ', and a crown 130.

During assembly, the base 127 is put in place first, and fixed to the beam 10 ', then the bars are put in place with the end face 112 of the first end contiguous to the lateral face of the base. Then the crown 130 is lowered so that its bosses are housed in the recesses 114, 114 'of the bars, and secured by bolting.

Figures 2 and 3 clearly show that an intermediate piece is used per group G of rings, and per pair of side members 10, 10 ', which requires, in this case, that the side members are of even number.

According to the arrangement of Figure 6, we see that the intermediate pieces are arranged, for each pair of side members, alternately on one and the other of the side members of the pair, in the axial succession of the groups of rings.

It goes without saying, however, that this arrangement, which avoids the alignment of the second ends of bars on more than one group, with the risks of corresponding accumulation of games, is not imperative.

Of course, the invention is not limited to the examples described, but embraces all the variant embodiments thereof, within the scope of the claims.

Thus, it would be possible to have spacers on all the side members, the bars having similar nesting configurations at both ends.

It is also possible to envisage other nesting configurations than the quarter hemisphere configuration, for example pyramidal projections. In addition, instead of protrusions on the intermediate pieces and recesses on the bars, flush with the outer surface of the lining, one could make protrusions on the ends of the rod and recesses in the intermediate pieces on the inner face of the lining at the support on the side members.

Claims (8)

1. A furnace grate roller, the furnace grate being intended more particularly for the incineration of refuse and comprising a cascade of rollers (1, 2, 3, 4) driven in rotation about parallel horizontal axes (1b, 2b, 3b, 4b ), said roller comprising a cylindrical cage framework with, between two end portions (1c, 1'c), longitudinal members (10, 10', 10'', 10‴) which are disposed along generatrices regularly distributed around the periphery, and a tubular casing (1a, 2a, 3a, 4a) formed by a plurality of groups (G1, G2, G3) of circular rings generally in planes perpendicular to the axis and in axial succession from one end portion to the other, gaps (i) being provided between the rings for blowing combustion-supporting air, while the rings are segmented in the form of arcuate bars (11, 11', 11'', 11‴) which are fastened with play between two adjacent longitudinal members (10, 10'), and intermediate members (12) which are respectively associated with the groups (G1, G2, G3 ...) of rings and fixed to the longitudinal members (10, 10', 10'', 10‴) so as to limit the axial movement of the bars (11) in the groups (G), characterised in that each intermediate member (12) is fixed longitudinally to a longitudinal member (10') over the axial extent of a group (G) of rings, between contiguous ends (112) of bars, said intermediate member (12) and the contiguous ends (112) of bars (11) respectively having complementary nesting configurations (128, 129; 114, 114') for limiting the displacement of said bar ends (112) in the axial, radial and peripheral directions.
2. A roller according to claim 1 characterised in that each bar (11) is of a T-shaped cross-section in a plane passing through the axis of the roller, with a web (111) forming a rib directed towards said axis, and flanges (110) defining the outside surface of the casing.
3. A roller according to claim 2 comprising an even number of longitudinal members (10, 10', 10'', 10‴) of T-shaped profile, with a web in a plane passing through the axis of the roller, and flanges in the same tangential plane, characterised in that each bar (11) comprises said respective nesting configuration (114, 114') at a first end (112) and at its second end (115) a notch (116) in its web (111), which is arranged to engage over a flange of a longitudinal member (10'), an intermediate member (12) being associated with each group of rings (G1, G2, G3), per pair of longitudinal members (10, 10').
4. A roller according to claim 3 characterised in that the intermediate members (12) associated with the successive groups (G1, G2, G3) are fixed alternately to one (10) and the other (10') longitudinal members of a pair.
5. A roller according to one of claims 3 and 4 characterised in that each intermediate member (12) is of a generally parallelepipedic shape with two lateral faces (122, 123) substantially parallel to the web of the longitudinal member (10') to which it is fixed, and outside and inside faces (120 and 121 respectively) parallel to the flanges of said longitudinal member (10'), the nesting configuration in respect of the intermediate member (12) being formed by bosses ((1-6).128, (1-6).129) projecting from the lateral faces (122, 123) and decreasing in size from the outside face (120) until they merge into the lateral faces (122, 123), said bosses ((1-6).128, (1-6).129) being repeated in a direction parallel to the axis at a pitch corresponding to the width of a bar (11) plus that of a gap (i) for the blowing operation.
6. A roller according to claim 5 characterised in that the bosses ((1-6).128, (1-6).129) are in the shape of portions of spheres.
7. A roller according to one of claims 5 and 6 characterised in that the first end (112) of each bar (11) has recesses (114, 114') which are complementary to the bosses ((1-6).128, (1-6).129), provided in the corners of the outside face (110) of the bar at the first end (112), so that, within a group (G), two contiguous recesses in bars are complementary to an intermediate boss ((2-5).128, (2-5).129) of the intermediate member (12) while the latter has corner bosses (1.128, 6.128, 1.129, 6.129) which are half of the intermediate bosses ((2-5).128, (2-5).129).
8. A roller according to any one of claims 5 to 7 characterised in that the intermediate member (12) is in two radially superposable parts, a base (127) with flat lateral faces which is fixed directly on to the longitudinal member (10) and a top (130) which is fixed on to the base and which carries the nesting bosses ((1-6).128, (1-6).129).

Images