EP0466530A1 - Furnace wall and process for its manufacture - Google Patents

Abstract

Industrial furnace wall of the type comprising external metal armour characterised in that it comprises at least one layer of elastic insulating material (11) under compression in the direction perpendicular to the armour on its entire surface. <IMAGE>

Description

the present invention relates to furnace walls, more particularly to a process for producing a roof wall and the right foot of an industrial oven.

Industrial ovens in which ceramics, earthenware (bricks or other) are fired, etc. consist of a gas-tight metal wall from the outside towards the inside, then of a series of refractory materials arranged in successive layers.

• 1°- la paroi extérieure doit être absolument étanche
• 2°- les matériaux isolants doivent être bien répartis sur la surface de la tôle pour ne pas laisser de cavité au voisinage de la paroi de métal dans lesquelles le gaz corrosif et de la vapeur d'eau pourraient venir et ensuite détériorer la paroi.

The construction of these ovens presents two major difficulties, mainly because the cooking is carried out in a corrosive gaseous medium:

• 1 ° - the outer wall must be absolutely waterproof
• 2 ° - the insulating materials must be well distributed on the surface of the sheet so as not to leave a cavity in the vicinity of the metal wall in which the corrosive gas and water vapor could come and then deteriorate the wall.

It is known to produce such ovens, in particular by the method described in FR 70 43726 in which the outer wall is a sheet having a crenellated or corrugated profile. The metal plates are assembled and welded edge to edge, which forms a framework.

In this process, the stack of insulating materials is held against the metal wall by anchors which are on the one hand welded to the internal ribs of the sheet and on the other hand anchored in the refractory lining, as shown in FIG. 1. According to this process, the materials are the same dimensions as the plate on which they are previously stacked.

However, this process does not prevent the welds from being attacked by the present corrosive water and sulfur, and fairly quickly the oven is no longer sealed.

Indeed, while the mineral wool panels which include binders remain relatively rigid, the gold or fiber sheets collapse, which creates passages for the gas, in particular at the junction between two plates. adjacent and reveals pockets that the gas fills. And this subsidence is all the greater as the spacing of the anchors is important. The hot qaz attacks the welds which gradually give way, leaving a leak orifice.

The object of the invention is to overcome this drawback and an object is an industrial oven wall of the type comprising an external metal shield, characterized in that it comprises a layer of elastic insulating material compressed in the direction perpendicular to the shield.

• l'ossature est réalisée avec une tôle profilée comportant une succession d'ondes c'est à dire de rainures et nervures;
• les ancrages sont fixés au fond des rainures;
• la surface intérieure de la paroi est tapissée de laine minérale tassée, de façon à remplir les rainures et à présenter une surface sensiblement plane et régulière;
• entre la surface intérieure de la paroi métallique et la couche de fibres comprimées la paroi comporte au moins une couche de laine minérale comprimée inextensible ou analogue; de préférence ces touches sont constituées de panneaux juxtaposés, maintenus de manière connue en soi par des crans d'arrêt ou tout autre moyen équivalent prévus sur les ancrages.
• les dalles comportent un moyen de liaison entre elles permettant à chacune de s'appuyer et se retenir sur sa ou ses voisines.

The invention is also remarkable for the following characteristics:

• the framework is made with a profiled sheet comprising a succession of waves, that is to say grooves and ribs;
• the anchors are fixed to the bottom of the grooves;
• the inner surface of the wall is lined with packed mineral wool, so as to fill the grooves and to present a substantially flat and regular surface;
• between the inner surface of the metal wall and the layer of compressed fibers the wall comprises at least one layer of inextensible compressed mineral wool or the like; preferably these keys are made up of juxtaposed panels, held in a manner known per se by stops or any other equivalent means provided on the anchors.
• the tiles have a connecting means between them allowing each to lean on and hold onto its neighbor or neighbors.

• 1°.- on installe des tiges d'ancrages sur la paroi de voûte,
• 2°.- pour chaque dalle, successivement:
  • on présente une dalle entre deux tiges adjacentes, celle ci étant maintenue par un supprt inférieur,
  • on pose sur la dalle au moins une couche de fibres céramiques préalablement comprimées, et maintenues dans cet état par des sangles ou tout autre moyen,
  • on enlève les sangles, de telle sorte que la couche de fibres céramique se détende et occupe tout le volume séparant la dalle de la paroi, tout en restant comprimée.
  • on ajuste le positionnement de la dalle, et l'on met en plate aux extrémités des tiges des sabots de maintien des dalles.

The invention also relates to a process for producing the wall of an industrial oven thus defined, in which a sheet metal frame or shield is first prepared, the surface of which faces the interior of the oven is coated with an anti-corrosion product, characterized in that:

• 1 ° .- anchor rods are installed on the roof wall,
• 2 ° .- for each slab, successively:
  • there is a slab between two adjacent rods, this being maintained by a lower support,
  • at least one layer of ceramic fibers previously compressed and kept in this state by straps or any other means is placed on the slab,
  • the straps are removed, so that the ceramic fiber layer relaxes and occupies the entire volume separating the slab from the wall, while remaining compressed.
  • the positioning of the slab is adjusted, and the ends of the stems for holding the slabs are flattened at the ends.

Preferably the slab is presented obliquely and rests on the shoulders of the hooves closest to the previous row. The layer of compressed fibers is introduced on the inclined surface; remove the straps and straighten the slab.

• la figure 1 est une vue schématique en coupe d'une paroi selon la technique antérieure;
• les figures 2a, 2b sont deux vues schématiques en coupe d'une paroi selon l'invention, sur laquelle on a représenté les différentes étapes du procédé de montage.

By way of example and in order to better understand the invention, there is shown in the accompanying drawing an embodiment of an industrial oven wall according to the invention in which:

• Figure 1 is a schematic sectional view of a wall according to the prior art;
• Figures 2a, 2b are two schematic sectional views of a wall according to the invention, in which the various stages of the mounting process have been shown.

The wall according to FIG. 1 represents a known vault: it comprises an outer metal sheet 100, this sheet having a succession of grooves 101 and ribs 102. The anchors 105 are arranged, on the inner side, at the top of the ribs, and are there welded. The refractory materials are arranged in successive layers and held by the anchors. The compaction of the materials and the progressive collapse of the layers allows the passage of gases and their accumulation at the bottom of the grooves. The water in vapor condenses and runs on the edge of the ribs. This condensate is very corrosive and attacks the welds and the shell.

• 1°.- une tôle extérieure 1 métallique ou blindage.
  Celle-ci est mise en plate par plaques profilées ondulées présentant une alternance de nervures 2 et rainures 3, les plaques étant assemblées de manière à assurer l'étanchéité, par soudure 4 ou tout autre moyen connu. La face intérieure est traitée contre la corrosion: sablage, enduit de résine,etc.
• 2°.- des ancrages 5 fixés au fond des rainures 3 par boulonnage, soudage ou tout autre moyen équivalent, traités selon le tas contre la corrosion.
  Ces ancrages comportent une tige 6, le long de laquelle sont prévus des organes 7, connus en soi, destinés à maintenir des plaques de matériaux isolants 8, et qui portent à leur extrémité un sabot 9, en matériau réfractaire, circulaire ou autre présentant un épaulement. Les ancrages sont répartis le long des rainures et transversalement dans toutes ou partie des rainures consécutives de manière à former un quadrillage régulier. Comme le montre la figure 2, les sabots sont prévus pour porter des dalles 10 également en matériau réfractaire.
  La surface intérieure du four est dont formée par ces dalles maintenues par les sabots.
• 3°.- entre la tôle et les dalles au moins une couche 11 extensible de fibres céramiques comprimées.
  Le nombre de couches de fibres varie notamment selon leurs caractéristiques techniques (coefficient de transfert thermique,...) et la température maximale du four.

The wall according to the invention comprises:

• 1 ° .- an external metal sheet 1 or shielding.
  This is flattened by corrugated profiled plates having an alternation of ribs 2 and grooves 3, the plates being assembled so as to seal, by welding 4 or any other known means. The inside is treated against corrosion: sandblasting, resin coating, etc.
• 2 ° .- anchors 5 fixed to the bottom of the grooves 3 by bolting, welding or any other equivalent means, treated according to the pile against corrosion.
  These anchors comprise a rod 6, along which are provided members 7, known per se, intended to hold plates of insulating materials 8, and which carry at their end a shoe 9, made of refractory, circular or other material having a shoulder. The anchors are distributed along the grooves and transversely in all or part of the consecutive grooves so as to form a regular grid. As shown in Figure 2, the shoes are provided to carry slabs 10 also in refractory material.
  The interior surface of the oven is therefore formed by these slabs held by the shoes.
• 3 ° .- between the sheet and the tiles at least one extendable layer 11 of compressed ceramic fibers.
  The number of layers of fibers varies in particular according to their technical characteristics (heat transfer coefficient, etc.) and the maximum oven temperature.

In the embodiment, there is a first layer 12 of mineral wool packed on the metal wall so as to fill the grooves and form a substantially flat surface.

Under this first layer, there are successively several layers 13 of compressed mineral wool (for example three) presented in the form of inextensible panels juxtaposed. These panels are kept applied against the metal wall or, in the example against the first layer, by the holding members 7 provided along the rods of the anchors 6.

According to the invention, the number of layers of panels is provided so as to leave a substantial space 14 between the last layer and the lower pavement, into which the compressed stretch layer is introduced.

the dimension of this space 14 and the initial compression of the layer of fibers 11 are chosen so that the layer 11 can be easily introduced and, after expansion, it is still compressed. Thus all of the layers between the paving and the metal wall are permanently in compression.

In the exemplary embodiment, the space 14 is approximately 220 millimeters and the layer 11 of compressed fibers consists of superimposed strips; before compression the thickness is of the order of 275 millimeters. This layer is compressed, the thickness being reduced to 200 millimeters, and thus maintained by straps. It is introduced, placed on the paving and the straps are removed. The layer relaxes and fills the space of 220 millimeters.

This example is not limiting and the compressed layer can be produced in various ways without departing from the scope of the invention; the sheet can in particular be compressed without being cut into superimposed strips, but wound or folded over itself several times, etc.

The flattening of the paving and the compressed layers is carried out, in the embodiment, as follows: first of all the rods 6 (without shoe 9) and the first inextensible layers 12, 13 are flat . The tiles are then installed one by one with the layers compressed, and held by the shoes. In more detail, we present a slab between two consecutive rows of rods 6 ′, 6˝; the slab rests by one of its edges on the shoulders of the end shoes 9 ′ already in place and is held in the downward inclined position, as shown in FIG. 2a, by any support 16; the layer compressed by the upper edge is then introduced, the straps 17 are removed and removed: the layer then occupies the entire volume (FIG. 2b); we straighten it slab, which compresses the layer, to the desired level and the 9 "shoes are installed.

The production method which has just been described is not limiting and other methods can be envisaged without departing from the scope of the invention.

In addition, according to an alternative embodiment not shown, the tiles have on at least two opposite edges connecting means allowing each of them to rest and / or restrain on its neighbor. These connecting means are for example made by concordant shape, of the tenon-mortise type, recess-projection in general, tile profile, free hinge, etc.

The wall is in compression throughout its thickness, which avoids the formation of pockets and passages allowing gas leaks.

This oven wall can be made both for the vaults, which are substantially horizontal, and for the vertical walls.

Claims (6)

Industrial oven wall of the type comprising an external metal shielding characterized in that it comprises at least one layer of insulating material (11) elastic in compression in the direction perpendicular to the shielding over its entire surface. Oven wall according to claim 1 characterized in that the framework or shielding is produced with a profiled sheet (1) comprising a succession of grooves (3) and ribs (2). Oven wall according to claim 2 characterized in that the anchors (6) are fixed to the bottom of the grooves (3). Oven wall according to claim 3 characterized in that the inner surface of the sheet (1) is lined with packed mineral wool (12), so as to fill the grooves (3) and to present a substantially flat and regular surface. Oven wall according to claim 4 characterized in that there is provided, between the inner surface of the metal wall and the layer of compressed fibers (11), at least one layer of compressed mineral wool inextensible (13) to the analog. Process for making the wall of an industrial oven according to any one of the preceding claims, in which a sheet metal frame or shield is first prepared, the surface of which faces the interior of the oven is coated with an anticorrosion product, characterized in than : 1 ° - anchor rods (6) are installed on the roof wall; 2 ° - for each slab (10), successively: * there is a dallle between two adjacent rods (6 ′, 6˝), this being held by a lower support (16), * at least one layer of previously compressed ceramic fibers (11) is placed on the slab (10), and maintained in this state by straps (17) or any other means; * the straps are removed, so that the layer of ceramic fibers relaxes and occupies the entire volume separating the slab from the wall, while remaining compressed; - We adjust the positioning of the slab, and we put in place at the ends of the stems of the shoes (9 ") holding the slabs.

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