EP1936308A1 - Rocking furnace with internal baffles - Google Patents

Abstract

The furnace has a tubular body whose base constitutes an inclined sole (1) e.g. flat sole, provided with an oscillation unit. The oscillation unit oscillates the tubular body along a longitudinal axis of the body. The tubular body has an upper part carrying a heating unit. The sole comprises baffles arranged such that a progression of products through the furnace follows a zigzag path (A). The baffles are defined by transversal partitions (10). The partitions are carried by a wall forming the sole and extended until a median longitudinal plane (XX) of the furnace.

Description

The present invention relates to the technique of continuous furnaces of the type called "oscillating furnace".

It is known to provide continuous furnaces which are constituted by an inclined tubular enclosure which is rotated so that the material to undergo heat treatment passes through said enclosure from side to side.

These furnaces, commonly used in cement and for the calcination of pulverulent products have two disadvantages.

The first is that one can have the burners at one or the other end of the enclosure, which makes it very difficult to control the temperature profile in the enclosure; the second is that it is very difficult to control the flow rate of products when it is desired to use the same oven for products of different sizes.

It was then proposed the use of oscillating furnaces, that is to say furnaces animated by a partial rotational movement in a reciprocating motion. This arrangement allows to position the burners in the upper part of the enclosure and thus to control and adjust at will the temperature along the path traveled by the products passing through the oven.

In the patent French 79-08040 of 30/03/1979 there is described an oscillating furnace comprising a substantially tubular furnace body, inclined, provided with means oscillating along its longitudinal axis, the bottom of said furnace having a central ridge oriented longitudinally.

This device is a remarkable improvement of the oscillating furnaces, but this type of furnace does not make it possible to treat a great variety of products, in particular for the sintering treatment of balls because their sphericity generates a too fluid flow, which does not allow a satisfactory treatment.

In a manner known per se, sintered balls are for example used in grinding processes or serve as a load in fluid pumping processes.

Such beads are still useful as catalyst or insulator supports.

The oscillating furnace according to the present invention is an oven comprising a substantially tubular body, inclined, provided with means oscillating along its longitudinal axis, said substantially tubular body having a sole and an arch carrying heating means, characterized in that the sole has baffles so that the progression of products passing through the furnace is in a zigzag path.

• les chicanes sont définies par des cloisons portées par la paroi formant la sole,
• les cloisons s'étendent au moins jusqu'au plan longitudinal médian du four,
• les cloisons sont séparées les unes des autres de distances égales de façon à constituer des chicanes définissant entre elles un parcours sinueux régulier pour les produits,
• les cloisons sont irrégulièrement espacées les unes des autres de façon à constituer des chicanes définissant entre elles un parcours sinueux irrégulier,
• la paroi de la sole comporte des alvéoles décalées définissant un parcours sinueux pour les produits,
• les alvéoles ont des formes et des profondeurs variables,
• les alvéoles ont des chambres semi-cylindriques destinées à provoquer des tourbillons,
• la sole est à section semi-circulaire,
• la sole est plate,
• il comporte une arête longitudinale dans son fond,
• il comporte une pluralité d'arêtes dans son fond.

The oven according to the invention is still remarkable in that:

• the baffles are defined by partitions carried by the wall forming the sole,
• the partitions extend at least as far as the median longitudinal plane of the furnace,
• the partitions are separated from one another by equal distances so as to constitute baffles defining between them a regular sinuous path for the products,
• the partitions are irregularly spaced apart from each other so as to form baffles defining between them an irregular sinuous path,
• the wall of the sole has staggered cells defining a sinuous path for the products,
• the cells have different shapes and depths,
• the cells have semi-cylindrical chambers intended to cause vortices,
• the sole is of semicircular section,
• the sole is flat,
• it has a longitudinal edge in its bottom,
• it has a plurality of ridges in its bottom.

• figure 1 : une vue, en coupe transversale d'un four oscillant de type connu,
• figure 2 : une vue schématique, en coupe transversale d'un premier exemple de réalisation de l'invention,
• figure 3 : une vue schématique, en plan, de la figure 2,
• figure 4 : une vue schématique, en coupe transversale, d'une variante de la figure 2,
• figure 5 : une vue schématique, en plan, de la figure 4,
• figure 6 : une vue schématique, en coupe transversale d'un deuxième exemple de réalisation de l'invention,
• figure 7 : une vue schématique, en plan, d'un troisième exemple de réalisation de l'invention,
• figure 8 : une vue schématique, en plan, d'un quatrième exemple de réalisation de l'invention,
• figure 9 : une vue schématique, en plan, d'un cinquième exemple de réalisation de l'invention,
• figure 10 : une vue schématique, en plan, d'un sixième exemple de réalisation de l'invention,
• figure 11 : une vue, en coupe transversale d'un four suivant un septième exemple de réalisation de l'invention, en position médiane,
• figure 12 : une vue du four de la figure 11 en position inclinée,
• figure 13 : une vue en plan du four de la figure 11.

By way of example and to facilitate understanding of the invention, the attached drawings show:

• figure 1 : a cross-sectional view of an oscillating furnace of known type,
• figure 2 : a schematic cross-sectional view of a first exemplary embodiment of the invention,
• figure 3 : a schematic view, in plan, of the figure 2 ,
• figure 4 : a schematic cross-sectional view of a variant of the figure 2 ,
• figure 5 : a schematic view, in plan, of the figure 4 ,
• figure 6 : a schematic cross-sectional view of a second embodiment of the invention,
• figure 7 : a schematic plan view of a third exemplary embodiment of the invention,
• figure 8 : a schematic plan view of a fourth embodiment of the invention,
• figure 9 : a schematic plan view of a fifth embodiment of the invention,
• figure 10 : a schematic plan view of a sixth exemplary embodiment of the invention,
• figure 11 : a cross-sectional view of a furnace according to a seventh embodiment of the invention, in the middle position,
• figure 12 : a view of the oven from the figure 11 in an inclined position,
• figure 13 : a plan view of the oven of the figure 11 .

The figure 1 represents an oscillating furnace of known type.

The furnace itself has a tubular body consisting of a sole 1, covered with an upper part, or arch, 2 in the wall of which are disposed heating means such as burners 3 and thermal probes 4.

The tubular body 1-2 is carried by a frame 5 placed in a semi-circular cradle 6 carried by rollers 7, which serve to oscillate the cradle 6.

As visible in the drawing, the sole 1 of said furnace is generally flat.

The Figures 2 and 3 represent, schematically, a first embodiment of the invention.

The sole 1 of the furnace is of semicircular section and is provided with transverse partitions 10 carried by its wall and defining brewing chambers.

In the example shown, the angle α between the transverse partitions 10 and the wall of the hearth 1 is equal to 90 °, but it can be different, obtuse or acute. The routing of the products in the furnace is dependent on the orientation of said partitions 10 with respect to the wall of the hearth. When said partitions 10 are inclined towards the entrance of the oven, the products are partly brought back to the brewing chamber arranged upstream which extends their travel time in the oven. Conversely, when the partitions 10 are inclined towards the outlet of the oven, some of the products can be made to travel more quickly the oven.

To the Figures 2 and 3 the partitions 10 extend to the longitudinal median plane XX of the hearth 1, whereas in the example shown in FIGS. Figures 4 and 5 the partitions 10 go beyond said median plane and extend over more than half of the section of the hearth 1.

Said partitions 10 form baffles which force the products circulating in the oven in the general direction of the median plane XX to make a zigzag path A or B (the zigzags B being more accentuated than A) when the oven oscillates a chamber located on one side of the median plane XX to a chamber located downstream and on the other side of the median plane XX.

Although this is not shown in the drawing, such partitions 10 can equip a flat-bottomed oven such as that shown in FIG. figure 1 .

In the embodiment shown in figure 6 , the bottom of the hearth 1 is flat and has a plurality of ridges 11. Said ridges 11 cause additional stirring of the products during their overall transverse movement due to oscillations of the furnace. Said ridges 11 are arranged in any way in the bottom of the hearth, and are not necessarily longitudinal.

Although represented in a flat-bottomed oven, such ridges may also be provided in an oven of any section, for example circular.

Referring to the figure 7 we see that the partitions 10 may not be equidistant, but shifted so that the path C is not shifted.

According to an alternative embodiment not shown in the drawing, when the cross-sectional shape of the hearth allows it, the partitions 10 are rotatably mounted relative to the wall of the hearth to allow a modification of their orientation angle α in function of current production.

To the Figures 8 and 9 it is seen that instead of the partitions 10 can be formed in the side wall of the hearth 1, cells 12 offset longitudinally so as to define a sinuous path D of a cell 12 to the other.

Although this is not shown, it is possible to have cells 12 of variable shape and depth, which makes it possible to vary the speed of progression of the products according to the path D.

It is still possible to have the fingers 15 in the space that the products must travel in order to improve their mixing.

Similarly, in the examples of Figures 3, 5 and 7 arranging the partitions 10 in an irregular manner, to vary the rate of progression of the products along the paths A, B or C.

The figure 10 illustrates an alternative embodiment of the figure 9 in which the cells 12 comprise semi-cylindrical chambers which cause small eddies E, which increases the brewing effect of the products.

The Figures 11 to 13 illustrate another embodiment of the invention.

The partitions 10 are arranged as in the example of the figure 3 that is, they do not go beyond the median plane XX and are symmetrically distributed.

According to this variant the hearth 1 comprises, in addition to the partitions 10 a bottom which is not flat but which is provided in its median part with a ridge 14 (similar to that described in the aforementioned patent 79-0040), ridge that is located in the midplane XX.

We see that products 13, which at the figure 11 are on the right side of edge 14 swing to the left when the oven is oscillating ( figure 12 ).

The products are therefore subjected to a double movement: they are obliged to follow a sinuous course (A, B, C, D, E) which operates a lateral brewing and they undergo a stirring up and down crossing the ridge 14.

Although not shown, it is also possible to vary the spacing of the partitions 10 between them.

The various arrangements described above can be chosen and adapted to any shape of sole in order to regulate at will the speed of flow of products through the oven and the intensity of their brewing.

The implementation according to the invention of partitions that force the products to travel a zigzag path from a cell located on one side of the oscillating furnace to a cell located on the other side of the oscillating furnace, promotes the mixing of treated products in said furnace and provides a particularly homogeneous treatment of these products.

Claims (12)

Oscillating furnace of the type comprising a substantially tubular body, the bottom of which constitutes the inclined floor provided with means for oscillating it along its longitudinal axis, said substantially tubular body comprising a hearth (1) and an upper part (2) carrying heating means (3), characterized in that the sole (1) comprises baffles so that the progression of the products passing through the furnace is in a zigzag path (A, B, C, D, E). Oscillating furnace according to claim 1, characterized in that the baffles are defined by partitions (10) carried by the wall forming the sole (1). Oscillating furnace according to claim 2 wherein the partitions (10) extend at least to the median longitudinal plane (XX) of the furnace. Oscillating furnace according to Claim 2 or Claim 3, in which the partitions (10) are separated from one another by equal distances so as to constitute baffles defining between them a regular sinuous path (A, B) for the products. Oscillating furnace according to claim 2 or claim 3 wherein the partitions (10) are irregularly spaced from each other so as to form baffles defining between them an irregular sinuous path (C). Oscillating furnace according to claim 1 wherein the wall of the hearth comprises staggered cells (12) defining a sinuous path (D) for the products. An oscillating furnace according to claim 6 wherein the cells (12) have varying shapes and depths. Furnace according to claim 7 wherein the cells (12) have semi-cylindrical chambers for causing vortices (E). Oscillating furnace according to any one of claims 1 to 8 wherein the sole (1) of the furnace is semicircular section. Oscillating oven according to any one of claims 1 to 8 wherein the sole (1) of the oven is flat. Oscillating furnace according to any one of claims 1 to 10 having a longitudinal edge (14) in its bottom. Oscillating furnace according to any one of claims 1 to 11 having a plurality of ridges (11) in its bottom.

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