EP0516909A1 - Beam forming a heat expansion joint between adjacent zones of a grate, the bars of which are alternately fixed and moving - Google Patents

Abstract

The joint beam (1) according to the invention consists of elements (10) in longitudinal succession, arranged between two grate zones (2, 3) formed by a longitudinal succession of bars which are alternately fixed (2a, 3a) and moving (2b, 3b) in longitudinal reciprocating movement. An element (10) consists of an I-shaped frame with a core (13) between a lower flange (12) forming a sole and an upper flange (11) which forms a roof, and of two friction pieces (20, 30) with a U-shaped profile with a base (21) bearing against the edge of the corresponding grate zone (2, 3). Springs (45, 46) pass through the frame core (13) via slots (16, 17) and stress the friction pieces (20, 30) bearing against the edges of the zones (2, 3) to compensate the expansions of the latter. The frame and the friction pieces (20, 30) are a mechanically welded construction so as to obtain adequate impermeability between friction pieces (20, 30) and frame. <IMAGE>

Description

The invention relates to a jointed beam, intended to provide compensation for thermal expansion and sealing of a space between two sheets of hearth grates joined laterally and each composed of a longitudinal succession of bars which are alternately fixed and movable going back and forth, this beam being composed of elongated elements in longitudinal succession with an armature fixed to a support frame for grids, and with two lateral rubbers carried by this armature and urged to bear respectively against an edge of the grid ply by springs.

Hearth grates, for solid fuels, and in particular for the incineration of urban residues, generally consist of bars in longitudinal succession, formed of elements joined transversely, which rest by a front end face on a dorsal face of an element of the previous bar in the longitudinal succession. These bars are alternately fixed and movable back and forth longitudinally, to produce an effect of poking and fractionation of the fuel. These sole are called grids, because they have passages for combustion air, pressurized under the grid, through which this combustion air reaches the fuel. In certain types of grids, these orifices are formed between two adjoining elements; in other types of grid, these orifices are formed in the dorsal face of the elements.

These orifices are designed to ensure a regular distribution of the combustion air throughout the extent of the grid ply, to be at best protected against blockage by ash or bottom ash, and sometimes to orient the angle of incidence of the combustion air in the igniting layer, in order to reduce the emission of fly ash. The modes of execution of these combustion air passage orifices are extremely diverse.

However, they all have in common the fear of significant air leaks between elements of bars, which come in parallel on the planned paths, and are likely to disrupt the distribution of the combustion air, and the progress of the hearth. However, due to the temperatures to which the grids are subjected, they are stressed in expansion and contraction; it is therefore necessary to provide sufficient cold clearances so that there is no excessive stress on the hot hearth walls, nor risk of seizure of the parts in relative movement.

It should however be specified that it is not necessary to seek absolute tightness, but to limit accidental leaks to a low flow compared to the normal flow of the orifices provided for the passage of air, so that the permeability ratio of the grate, or ratio of the surface offered to the passage of air relative to the total surface of grate fluctuates little with the grid area considered.

Insofar as the bar elements in the same transverse row do not move relative to each other, the sealing between these elements is easily made sufficient. Especially since, frequently, these elements are linked together during assembly of the grid to reduce the risk of seeing an element lifted by the fuel or a foreign body introduced with this fuel.

It is therefore at the edge of the grid tablecloth that the risks of creating parasitic leaks are most serious, and all the more so since measures have been taken to reduce the clearances between contiguous elements, which leads to the accumulation of displacements. by thermal expansion on the banks. It is necessary to provide expansion compensation joints on these banks.

It will be noted that one can be satisfied with a compensation joint on a bank of a sheet, as long as the width of the sheet is not excessive; in this case, the compensation joint is replaced on the other bank by a simple abutment surface.

It will be understood that the mounting of a compensation joint capable of absorbing lateral expansion play on a hearth wall provided with refractory brickwork poses anchoring and sealing problems, the steels or cast irons used for the execution of the compensation joint having expansion coefficients different from those of bricklaying.

Thus, in particular in the case of large hearths, it is necessary to split the grid along its width into sheets, with the interposition of a compensation joint between two joined sheets. This joint, formed of successively elongated elongated elements, takes on the appearance of a beam.

Patent FR-A-1,532,280 describes such a beam, or elastically compressible partitions, consisting of shell elements, spaced from one another by springs or counterweights, which form friction bearing on the edges of the grid layers. In a particularly simple embodiment, the shells have a U-shaped profile and one fits into the other, which rests slidably on a structure which connects to the support structures of the grid layers.

In more elaborate embodiments, the compensating beam comprises a reinforcing element fixed to a support structure, and two shells which overlap at their top, separated from one another by two levers in cross-pieces with a common central axis biased downward by a spring or counterweight. The effect of the spider is, in response to the stress down its axis, to tend to open in scissors by pushing in parallel the shells against the edges of the sheet.

Patent FR-A-2 352 250 substantially repeats the previous embodiment. However, the half-shells, instead of being slippery on the frame, are mounted suspended at the end of interior crutches erected almost vertically. This last embodiment aims to give independence to the movements of the half-shells, and to reduce the risks of seizure of the half-shells on the frame. Furthermore, an elongated frame supports several pairs of half-shells, in order to be able to replace deteriorated half-shells by handling only parts of limited weight.

The joints or compensating beams of the previous state of the art have the drawback of using molded parts of relatively complicated shape, and of having somewhat complex mechanisms, of delicate assembly and which are liable to resist poorly when foreign bodies are introduced into the hearth with the fuel, which is not uncommon in the incineration of urban waste.

And the advantages announced appear relative, in the sense that they relate to successive improvements of the same basic design.

The object of the invention is to produce a compensating joint beam as defined above, which is of simple construction and installation, with the minimum of moving parts or joints, and which is protected against shocks coming from the combustible layer.

Consequently, the invention proposes a jointed beam, intended to provide compensation for thermal expansion and sealing of a space between two sheets of hearth grates joined laterally and each composed of a longitudinal succession of bars which are alternately fixed and movable in back and forth, this beam being composed of elongated elements in longitudinal succession with a frame fixed to a support frame for grids and with two lateral rubbers carried by this frame and stressed bearing respectively against an edge of the grid ply with springs, characterized in that the frame has an I-profile with a vertical core between a lower wing forming a fixing base and an upper wing forming a roof, the two wipers having a U-shaped profile with a vertical base between two branches substantially parallel to the wings of the frame, fitting into it with little play while moving towards the core, the base having a flat outer face in abutment against the bank of respective ply and an internal face between the branches, coil springs passing through openings in the core perpendicularly to the latter being compressed between the internal faces of the wiper bases.

Thanks to this embodiment, the springs act directly to support the wipers against the edges of the sheets; these wipers find their support orientation independently of one another. The upper armature wing which is a fixed part protects the wipers against the forces and shocks which come from the fuel layer. Furthermore, the simple shapes of the parts allow manufacturing by mechanical welding, with surface conditions, in particular for the parts susceptible of relative movements, more favorable than if the parts came from the foundry. This kind of manufacturing also makes it possible to adapt the metal of each constituent part to the mechanical or thermal stresses that it must support.

Preferably the armature and the wipers comprise transverse end plates which extend, for the reinforcement from one wing to the other over the entire width of the lower wing and, for the wipers, from a branch to branch over the entire length of these branches.

These plates determine a confinement of the interior space both of the armature and of the friction shoes, so that each element has a sealing autonomy; consequently, there is no need to provide joints between wipers, as well as between frames, for two consecutive elements.

Preferably also, the lower wing of the frame is pierced with orifices in the plane of the core, and opening into recesses made in the latter.

Through these openings, the combustion air under pressure under the grate has access to the interior of the joined beam element, and tends to exit through the interstices between armatures and rubbers, to reduce the penetration of fine particles from the layer in combustion.

• la figure 1 est une vue perspective d'une partie de poutre joint selon l'invention, disposée entre deux nappes de grilles de foyer accolées ;
• la figure 2 est une vue latérale, partiellement coupée et arrachée d'un élément de poutre joint ;
• la figure 3 est une coupe suivant le plan III-III de la figure 2 ;
• la figure 4 est une coupe suivant les plans décalés IV-IV de la figure 2 ;
• la figure 5 est une vue du dessus du raccordement de deux éléments de poutre joint ;
• la figure 6 est une vue de côté d'une plaque couvre-joint.

Secondary 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:

• Figure 1 is a perspective view of a part of jointed beam according to the invention, arranged between two layers of adjoining hearth grates;
• Figure 2 is a side view, partially cut away and broken away of an attached beam member;
• Figure 3 is a section along the plane III-III of Figure 2;
• Figure 4 is a section along the offset planes IV-IV of Figure 2;
• Figure 5 is a top view of the connection of two joined beam elements;
• Figure 6 is a side view of a cover plate.

According to the embodiment chosen and shown in Figure 1, two grid plies 2 and 3 are joined laterally on either side of a joined beam 1. The grids 2 and 3 are each formed of a longitudinal succession of bars 2 a , 2 b , 2 a ..., 3 a , 3 b , 3 a ... respectively, each bar supported by the lower edge of a front face on a dorsal face of a previous bar, the first bar upstream bearing on a hearth trim plate, and hooked from the rear to a support fitting, alternately connected to the frame of grid and a movable chassis back and forth longitudinally. Thus the bars 2 a , 3 a are fixed, and the bars 2 b , 3 b driven back and forth longitudinally. The bar elements are traversed by blowing orifices, and pressurized boxes are placed under the grate layers to supply the hearth with combustion air through the blowing orifices. A detailed description of such a
grid, in particular in patent documents FR-A-2 574 160 and EP-A-0 191 254.

The jointed beam 1 is made up of a longitudinal succession of oblong elements such as 10 which include a frame and lateral rubbers 20 and 30 urged respectively against the edges of plies 2 and 3 supported by their planar external faces.

As will be seen in more detail in FIGS. 2, 3 and 4, the joined beam element comprises an I-profile reinforcement, with a vertical core 13 between an upper wing 11 which forms the roof of the element 10, and a lower wing 12 forming a sole for fixing to the grid frame. The element 10 also includes the two wipers 20 and 30 which affect a U-shaped profile, with a vertical base 21, 31, and two branches 22, 24 and 32, 34 respectively, facing the reinforcing core 13, substantially parallel to the wings 11 and 12 of reinforcement between which they fit together with a slight clearance. Coil springs 45, 46 transverse pass through the reinforcement core 13 by circular openings filled with sections of tubes 16 and 17 substantially midway between the wings 11, 12, to urge the sliding shoes 20, 30 apart. The springs 45, 46 are centered in the sections of tubes 16, 17 by interlocking around circular projections 21 a , 21 b , 31 a , 31 b attached to the internal faces of the bases 21, 31. This arrangement of the springs ensures flat support of the wiper on the edge of the grid ply.

The wipers 20, 30 are held on the frame, with a limited projection, by vertical pins 41, 42, 43, 44, which engage in housings in the wings 11 and 12, and pass through the branches 22, 24 , 32, 34 passing through oblong lights, not referenced.

The armature and the wipers have, at their longitudinal ends, end plates 14 and 15 for the armature, which extend from wing 11 to wing 12, with a width corresponding to that of the wing 12, and 23, 33, 25, 35 for wipers, which extend from one branch to another.

Note that the assembly of the frame, core 13, wings 11, 12 and end plates 14, 15, and wipers 20, 30, bases 21, 31, branches 22, 24, 32, 34, and plates end 23, 25, 33, 35, is produced by mechanical welding, which makes it possible to use refractory steel flats with smooth and parallel faces, and to ensure a dimension accuracy greater than that which is obtained in foundry. The clearances between wipers and armatures can thus be properly adjusted. Furthermore, the wipers fit into the reinforcement along four sides, which provides the element 10 with an independent seal, in the sense that here seal is understood, that is to say leaks which do not affect the combustion air blowing regime.

However, the internal volume of the element 10 should be in communication with the blowing boxes, in order to be overpressure relative to the hearth and to prevent fly ash, or fumes, from entering the interior of the element. For this purpose, the sole wing 12 is provided with transverse bars 12 a , 12 b , 12 c , 12 d , which provide a space between this sole and a support beam in the grid frame. Between these bars, the sole 12 is pierced with orifices 19 a , 19 b , 19 c , in the plane of the core 13, these orifices opening into recesses 18 a , 18 b , 18 c of this core 13, in round arch shape.

As can be seen better in FIG. 3, the element 10 ′, of which only the end is shown, is placed in succession with the element 10, with its rear armature end plate 15 ′ bearing against the reinforcing front plate 14 of the element 10. The bases 21 and 31 of the element 10 are extended by slotted bars 26 a , 26 b , 36 a , 36 b . The bases 21 'and 31' of the element 10 'also have slotted bars 26' b 36 ' b facing the bars 26 a , 36 a . Flat keys 27 a, 37 a are inserted into the pair of mortises faced, for coupling rubbing members.

As shown in FIGS. 5 and 6, a joint cover 50 formed from a cambered flat on the profile of the upper wing 11 of reinforcement, fills the gap between the upper wings 11 and 11 'of the reinforcements of two elements successive, this joint cover being welded to only one of the roof wings 11 and 11 '.

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

In particular, it goes without saying that it is possible to produce all or part of the parts constituting the expansion joint in the foundry, even if the description has been made of parts manufactured by mechanic welding.

Claims (10)

Joint beam (1), intended to provide compensation for thermal expansion and sealing of a space between two layers (2, 3) of hearth grates joined laterally and each composed of a longitudinal succession of alternately fixed bars (2 a , 3 a ) and movable back and forth (2 b , 3 b ), this beam being composed of elements (10) elongated in longitudinal succession with a frame fixed to a support frame for grids and with two lateral rubbers ( 20, 30) carried by this frame and urged to bear respectively against an edge of the grid ply (2, 3) by springs (45, 46), characterized in that the frame has an I-profile with a vertical core (13) between a lower wing (12) forming a fixing base and an upper wing (11) forming a roof, the two wipers (20, 30) having a U-shaped profile with a vertical base (21, 31) between two branches ( 22, 24; 32, 34) substantially parallel to the wings (11, 12) of the frame, fitting into it with a small clearance while moving towards the core (13), the base (21, 31) having a planar external face in abutment against the respective ply bank and an internal face between the branches (22, 24; 32, 34), coil springs (46, 47) passing through slots in the core perpendicularly to the latter being compressed between the internal faces of the bases (21, 31) of wipers. Beam according to claim 1, characterized in that the openings through which the springs (45, 46) pass are circular and filled with sections of tubes (16, 17) substantially coaxial with the springs. Beam according to either of Claims 1 and 2, characterized in that the openings are made in the core (13) substantially halfway between the wings (11, 12). Beam according to claim 3, characterized in that a beam element (10) has two springs (45, 46). Beam according to any one of claims 1 to 4, characterized in that the internal faces of the bases (21, 31) of friction shoes have projections (21 a , 31 a , 21 b , 31 b ) in the form of discs, around which are centered the coil springs (45, 46). Beam according to any one of Claims 1 to 5, characterized in that pins (41, 42, 43, 44) pass through the frame perpendicular to the wings (11, 12) and pass through the branches (22, 24; 32, 34) of wipers by oblong slots parallel to the axes of the springs (45, 46). Beam according to any one of Claims 1 to 6, characterized in that the reinforcement and the friction elements comprise transverse end plates (14, 15; 23, 25; 33, 35) which extend, for the reinforcement, from one wing to another over the entire width of the lower wing (12), and for wipers, from one branch to another over the entire length of these branches (23, 25; 33, 35) . Beam according to any one of Claims 1 to 7, characterized in that the sliding shoes (20, 30) have mortises (26 a , 26 b , 36 a 36 b ) at their longitudinal ends which extend parallel to the face external base, and are suitable for receiving a key (27 a , 37 a ) for coupling between wipers of successive elements (10, 10 ′), this key being housed in half in each of two facing mortises. Beam according to any one of Claims 1 to 8, characterized in that a joint cover (50) is arranged overlapping a transverse interval separating two joined elements (10, 10 ') in the longitudinal succession, covering the upper wings of the reinforcements respective, and fixed to only one of these two frames. Beam according to any one of Claims 1 to 9, characterized in that the lower wing (12) of the frame is pierced with orifices (19 a , 19 b , 19 c ) in the plane of the core (13), and opening into recesses (18 a , 18 b , 18 c ) formed therein.

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