EP0250341A1 - Orientable feeding pipes for furnaces suited for firing carbonaceous blocks - Google Patents

Abstract

The invention relates to a pipe for a chamber oven intended for the firing of carbonaceous blocks, this suction or blowing pipe comprising a main body provided with a plurality of fittings (10) to which are connected so-called “udder” pipes. in number equal to that of the heating partitions constituting the chambers of the oven, each of these udders having to fit on the openings called "openings" (8) arranged at the upper part of each heating partition. Each udder consists of at least two tubular elements, arranged in series, a first element (15) provided, on the one hand with a flat flange (18) which cooperates in contiguous relation and in rotation, with a flat flange (19). ), and, on the other hand, a flat flange (27) which cooperates, in contiguous and rotating relation with a flat flange (26) disposed at the upper part (16A) of the second element (16), the element (15) and element (16) having over at least part of their height an axis inclined at an angle a with respect to the axis (23) perpendicular to the plane of the flanges.

Description

TECHNICAL AREA OF IPVENTION

The invention relates to an improvement in the blowing and suction pipes of ovens with open chambers called "rotating fire" or "fire advancement" for cooking carbonaceous blocks (anodes or cathodes) intended in particular for production tanks of aluminum by the Hall-Héroult process, but also carbon blocks of all types generally intended for electrometallurgical furnaces.

TECHNICAL STATE

In what follows, we will denote by the expression "carbon block", any product obtained by shaping a carbon paste, and intended, after baking, for use in electrometallurgy ovens.

For example, the carbon anodes intended for aluminum production tanks by electrolysis of alumina dissolved in molten cryolite are obtained by placing. in the form of a carbonaceous paste resulting from the kneading, at around 120 to 200 ° C, of a mixture of pitch and ground coke. After shaping, the anodes are baked for a hundred hours at a temperature of the order of 1100 to 1200 ° C. Other types of carbon blocks are obtained by the same process.

Although there are a few continuous baking processes in a tunnel oven, a large part of the cooking facilities in service in the world to date are of the "chamber furnace" type called "ring furnace" or " advancing fire ". These ovens are themselves divided into two categories, closed ovens and so-called "open chamber" ovens, described in particular in US Pat. No. 2,699,931 and which are the most used. The present invention applies more particularly to ovens with open chambers.

This type of oven has two parallel spans, the total length of which can reach more than a hundred meters.

Each span comprises a succession of chambers, separated by transverse walls and open at their upper part, to allow the loading of the raw blocks and the unloading of the cooled cooked blocks. Each chamber comprises, arranged parallel to the major axis of the oven, a set of hollow partitions, with thin walls, in which the hot gases ensuring the cooking will circulate, alternating with cells in which the baking blocks are stacked which will then be embedded in carbonaceous dust (coke, anthracite or ground carbonaceous residues or any other powdery packing material). There are for example 6 alveoli and 7 alternating partitions per room.

The hollow partitions are provided, at their upper part, with closable openings called "openers"; they also include baffles to lengthen and distribute the path of the combustion gases more uniformly.

The heating of the oven is ensured by burner ramps, having a length equal to the width of the chambers, and the injectors of which are placed on the openings of the chambers concerned. Upstream of the burners (relative to the direction of advance of the fire), there is a combustion air blowing pipe, and, downstream, a suction pipe for the burnt gases. The heating is ensured both by the combustion of the injected fuel (gas or fuel), and by that of the pitch vapors emitted by the blocks during cooking.

As the cooking takes place, the blowing pipe-burner-suction pipe assembly is advanced, for example every 24 hours, each chamber thus ensuring, successively, the loading functions of the raw carbon blocks, natural preheating (by combustion gases), forced preheating and cooking at 1100-1200 ° (so-called full fire zone), cooling of carbonaceous blocks (and preheating of combustion gases), unloading of cooked carbonaceous blocks, possible repairs, and recovery of a new cycle.

TECHNICAL PROBLEM TO BE SOLVED

One of the main problems with operating these ovens, whose structure is continuously subjected to cycles of cooling and heating, is the installation of pipes of blowing and aspiration on the openings of the rooms. Indeed, at each stage of advancement of the fire, that is to say of the burner ramps, it is necessary to move, at the same step and in the same direction, the suction and blowing pipes. It is important that each of the pipes of the pipes (often called "udders") is introduced into each of the corresponding ports without damaging them and ensuring a suitable seal, especially with regard to the suction pipe, so as to avoid any entry. unwanted air. Relatively easy on a new oven, or on a refurbished partition, this operation is much less so on a room more or less deformed by thermal stresses and the operations of loading and unloading of the anodes. It is not uncommon for retouching and clogging to be carried out to ensure a tight connection between the udders and the workpieces.

OBJECT OF THE INVENTION

The object of the invention is a pipe -which can function as well as a blow pipe as a suction pipe- each of whose teats is made orientable and adjustable in height so that at the time of placement on a new chamber, each udder can be simply and quickly oriented by rotation, so that the axis of the lower part of each udder coincides substantially with the axis of the corresponding opening and adapts contiguously to this opening, with height adjustment by sliding if necessary.

More specifically, the object of the invention is a pipe for chamber furnaces intended for cooking carbonaceous blocks for the production of aluminum, this pipe comprising a main body provided with a plurality of nozzles to which connect tubing called "udders" in a number equal to that of the lines of heating partitions constituting the partitions of the rooms, each of these udders having to adapt to the openings called "openers" disposed at the top of each heating partition or of the walls transverse separating the different chambers of the oven.

According to the invention, each udder is constituted by at least two tubular elements, arranged in series, a first element provided on the one hand, at its upper part, with a flat flange which cooperates in contiguous relation and in rotation, with a flat flange disposed at the lower part of the nozzle, and on the other hand, at its lower part, a flat flange, in contiguous relation, and in rotation, with a flat flange disposed at the upper part of the second element, the first and second elements having, at least over part of their height, an axis inclined at an angle 0 (relative to the axis perpendicular to the plane of the flanges.

The plane flanges are parallel to each other and parallel to the plane containing the openings which is normally a horizontal plane.

To ensure the height adjustment, each udder further comprises a third tubular element in contiguous relation by sliding partial engagement and coaxial with the lower part of the second element, the lower part of this third element adapting in tight relation on the 'workman. The horizontality faults are absorbed by the play at the level of the interlocking of the third tubular element.

Preferably, the height adjustment is coupled to one of the rotation adjustments of the udder by a connecting rod / crank system simultaneously allowing the rotation of the second element around the flange and the sliding of its lower part.

DESCRIPTION OF THE FIGURES Figures 1 to 6 illustrate the invention.

• . Figures 1 and 2 relate to the prior art and recall the usual structure of an oven with open chambers for cooking carbon anodes.
• . FIG. 3 represents, in section, an orientable and adjustable udder along the axes X, Y and Z, according to the invention. The control system, handles + links, which is in front of the cutting plane has been shown in dotted lines.
• Figures 4 and 5 show an alternative embodiment of the invention.
• . Figure 6 is a section of Figure 3 in a plane perpendicular to the plane of this figure.

Figures 1 and 2 recall, for a good understanding of the invention, the structure of a conventional chamber oven to which the present invention applies: in the section of Figure 1, we see the partitions (1), connected at their upper part by the "udders" (2) to the pipe (3) itself connected to the general manifold (4). The blowing and suction pipes can be, depending on the case, connected to the rooms of the rooms or to the rooms of the transverse walls (9) according to our patent FR 2 535 834. In the cells (5) are arranged the carbon blocks (6 ), visible on the cutaway of the left side of figure 2.

The purpose of the baffles (7) of the heating partitions is to lengthen the path of the hot gases and to homogenize the temperature in the partition.

At the upper part of the chambers (or of the transverse walls), the closable openings (8) allow the installation of the burner ramps (not shown), blow pipes or air suction pipes (3), and, in some cases, measuring devices (thermocouples, depressometers). The successive chambers are separated by transverse walls (9). The main axis of the oven is indicated by line XX '.

Each udder (2) of the suction pipe (3) is connected to an opening (8) of a given chamber, in tight relation. The upper part of the udder is connected to the pipe (3) by a nozzle (10) in which is generally disposed a movable flap (11) which allows, by its rotation about an axis (11A) to regulate the flow in each series of chambers (5).

According to the invention, the vertical part of the udder which enters the opening is made orientable so that the axis (12) of the lower part substantially coincides with the axis (13) of the opening considered.

In practice, the orientable udder (14) according to the invention makes it possible to make up for a deviation of ± 50 mm in eccentricity (X and Y axes) and a deviation of + 50 mm in height (Z axis), these figures being given by way of example and not constituting a limitation of the invention.

• a) une partie cylindrique haute (15A), munie d'une bride (18) qui coopère avec la bride (19) de l'ajutage (partie droite)(10). Ces deux brides sont en relation étanche et l'élément (15) peut effectuer un mouvement de rotation par rapport à la bride (19). La bride (18) est serrée contre la bride (19) par une contre-bride boulonnée (20). On peut interposer entre les brides (18) et (19) un joint d'étanchéité résistant aux températures élevées (500 à 600°C) par exemple du type métalloplastique (cuivre + fibres minérales); Il peut aussi être constitué par un simple bourrage de graisse pour hautes températures injecté dans l'espace libre entre les brides (18) et (19), par un graisseur (21). La partie haute (15A) et la partie droite de l'ajutage (10) sont coaxiales.
• b) Une partie centrale (15B), cylindrique, dont l'axe (24) est incliné d'un angle ^oC par exemple de 20 à 45°, par rapport à l'axe (23) de la partie haute (cette valeur de 20 à 45° ne constitue pas une limitation de l'invention, mais elle est donnée à titre indicatif).
• c) Une partie basse (15C), cylindrique, dont l'axe (25) est parallèle à l'axe (23) de la partie haute, mais déporté d'une distance égale à l'écart maximum supposé entre l'axe (13) de l'ouvreau et l'axe (23) de l'ajutage (10). On a indiqué précédemment que cette valeur maximale probable pouvait être fixée, par exemple à 50 mm.

To obtain the alignment in X and Y, that is to say along the major axis XX 'and along the transverse axis of the furnace (Y, Y'), the orientable udder (14) is made up of at least two elements, on the one hand an upper element (15) which is connected to the nozzle, straight part (10) itself connected to the pipe (3) and on the other hand, an intermediate element (16) for adjustments in X and Y. A lower element (17) which is connected to the opening (8) makes it possible to ensure the adjustment in Z (height). The upper element (15) itself has three parts:

• a) a high cylindrical part (15A), provided with a flange (18) which cooperates with the flange (19) of the nozzle (straight part) (10). These two flanges are in tight relation and the element (15) can perform a rotational movement relative to the flange (19). The flange (18) is clamped against the flange (19) by a bolted counter flange (20). It is possible to interpose between the flanges (18) and (19) a seal resistant to high temperatures (500 to 600 ° C), for example of the metalloplastic type (copper + mineral fibers); It can also be constituted by a simple stuffing of grease for high temperatures injected into the free space between the flanges (18) and (19), by a greaser (21). The upper part (15A) and the right part of the nozzle (10) are coaxial.
• b) A central part (15B), cylindrical, whose axis (24) is inclined at an angle ^o C for example from 20 to 45 °, relative to the axis (23) of the upper part (this value from 20 to 45 ° does not constitute a limitation of the invention, but it is given for information only).
• c) A cylindrical lower part (15C), the axis (25) of which is parallel to the axis (23) of the upper part, but offset by a distance equal to the maximum deviation assumed between the axis ( 13) of the outlet and the axis (23) of the nozzle (10). It was indicated previously that this maximum probable value could be fixed, for example at 50 mm.

• a) une partie cylindrique haute (16A), munie d'une bride (26) qui coopère avec la bride (27) de la partie basse (15C) de l'élément supérieur (15).
• b) Une partie centrale (16B), cylindrique, d'axe (24A) incliné d'un angle 0<2 en principe égal à ₀(1 (ou du même ordre de grandeur) par rapport à l'axe (25).
• c) Une partie basse (16C), cylindrique, dont l'axe (28) est déporté, par rapport à l'axe (25), d'une distance égale à l'écart maximum à corriger, comme indiqué précédemment, par exemple 50 mm.

The intermediate element (16) comprises, in the same way as the upper part (15):

• a) a high cylindrical part (16A), provided with a flange (26) which cooperates with the flange (27) of the lower part (15C) of the upper element (15).
• b) A central part (16B), cylindrical, with an axis (24A) inclined at an angle 0 <2 in principle equal to ₀ (1 (or of the same order of magnitude) relative to the axis (25).
• c) A cylindrical lower part (16C), the axis (28) of which is offset, with respect to the axis (25), by a distance equal to the maximum deviation to be corrected, as indicated above, for example 50 mm.

The cooperation, in contiguous relation and in rotation, of the intermediate element (16) with the upper element (15) is carried out by the same means as at the level of the connection between the element (15) and the nozzle (10). Likewise, the two flanges (27) and (26) fixed to each other by bolts can receive a seal, for example metalloplastic, or a stuffing of grease for high temperature injected by the greaser (21).

Compensation for the Z offsets (i.e. along the vertical axis ZZ 'of the furnace (fig. 2) is obtained by the lower element (17), which adapts to the opening (8) in tight relation.

In the case shown, for example, in Figure 3, in the lower part, the lower element (17) presses on a groove (30) at the periphery of the opening. This groove may include a seal (29) resistant to high temperatures, for example in braided or felted mineral fiber. In addition, the element (17) can be secured by tie rods, the lower part of which is sealed in the masonry of the furnace. Note that, in Figure 6, the support of the element (17) takes place on a peripheral relief (32) of the opening (8) by means of a double flexible seal (43).

The intermediate element (16) and the lower element (17) cooperate by a fitting (33) which makes it possible to make up for a difference in level (dimension Z) between the inlet of the opening and the lower part of the orientable udder (14).

Taking into account thermal expansions and possible defects in flatness of the openings, it would be difficult to achieve a perfectly tight sliding fitting. This sealing can be ensured by means of a flexible connection, such as the bellows (34) which is fixed, in the upper part, to the groove (35) and in the lower part to the groove (36). This bellows must be able to withstand, in continuous service, temperatures of the order of 300 to 400 ° C. It is, for example, made of glass fibers impregnated with a fluorocarbon polymer.

The flanges and counter flanges (19) (20) and (27) (30) are pierced with holes for the passage of bolts, so as to maintain the cohesion of the assembly. The free rotation of the assembly is ensured by a thick lubricant (grease) for high temperature injected into the space between the flanges, by means of grease fittings (21) (22). The intermediate element (16) further comprises an operating device, constituted by a double rod-crank system, which makes it possible to simultaneously align the axes (8) and (12) in Y, that is to say ie along the transverse axis of the furnace, while maintaining or retouching the alignment in X. When the axes are aligned in X and Y, this same device makes it possible to lower the lower element (17) until contact the opening (8) (Z alignment). This operating device, formed symmetrically with respect to a plane passing through the axis (28), comprises an axis (38) passing diametrically through the element (16A), supporting at its two ends a disc (37A) (37B ) provided with a radial operating handle (38A, 38B) and, is connected by a joint (43A, 43B) not coincident with the axis (38), at the upper end of a link (40A, 40B) , the lower end of which comprises a hinge (39A, 39B) fixed to the lower element (17).

The detail of the system appears in FIG. 6 which is a section of FIG. 3 passing through the axis (38) and, in a plane perpendicular to FIG. 3.

The operation of the device according to the invention is as follows, the lower element (17) being raised to the maximum, the suction pipe is put in place, and the operator spots any deviations between the axis (13), each workpiece, and the axis (12) of the lower element (17). This axis (12) can also be materialized by a rigid metal rod supported by three spacers.

The operator, by acting on the handles (31) realizes the alignment of the axes (13) and (12) in X, that is to say along the major axis of the oven; . then acting on the handles 38A and 38B, it realizes the alignment of the axes (13) and (12) in Y, that is to say along the transverse axis of the furnace, while maintaining or retouching the alignment at X. At this moment, the axes (13) and (12) being aligned, it only remains to operate the adjustment along the Z axis, that is to say to lower the lower element ( 17) until contact with the groove of the opening (8).

This last maneuver is also carried out using handles (38A, 38B), but this time in rotation about the axis (38). The lower element (17) is guided during its alignment in Z (ascent or descent) is ensured by an oblong hole (41) formed in the element (16) in which slides a lug (42) integral with the element (17).

This set of operations, easy and quick, will be repeated on the 6 and 7 teats of the suction pipe, which will thus be perfectly adjusted to the 6 or 7 openings of the room or of the separation wall concerned.

It can be noted that the structure of the upper (15) and intermediate (16) elements could be simplified, as shown in FIGS. 4 and 5, by partially or totally eliminating the cylindrical parts with a vertical axis, and keeping only the parts medians (15A, 16A) with axis inclined at an angle 0 (.

In FIG. 5, the element (16A) has been turned by an angle so as to compensate for the deviation "e", in Y of the axis (13) of the workpiece with the axis (23) of the nozzle (10).

We will also note the catching up in Z, of the difference in height h of the opening by playing on the sliding junction (33). The difference existing between the sliding junction (33) and the intermediate element (16) makes it possible to compensate for a possible defect in the flatness of the opening.

In the case of FIGS. 4 and 5, the reference of the axes (23) (24) (24A) (25) and (28) will be taken relative to the planes of the junction flanges (18) (19), (26) ( 27), since there is no longer a cylindrical part. This reference remains valid in the case of FIG. 3. The plane of the flanges is normally horizontal.

Furthermore, the invention is not limited to the embodiment of the connecting flanges between the elements (10) (15), (15) (16) or the fitting between (16) (17). Any equivalent means making it possible to ensure rotation keeping the tight junction and a height adjustment also keeping the tight junction is part of the invention.

Finally, the determination of the angle 0 (can be carried out by use from simple geometrical considerations, by considering on the one hand the height of the inclined axis part of the udder and the eccentricity deviation to be made up (of the order of 50 mm, and beyond if necessary). The height of the inclined part of an element (15) or (16) being for example 90 mm, we will have tg α = 50/90, hence 29 °.

BENEFITS PROVIDED BY THE INVENTION

In addition to the ease of alignment in X and Y of the axes of the udders with the axes of each of the openings, it should be emphasized that the adjustment in Z (in height) allows, by raising the lower elements (17) as much as possible, during the assembly, to avoid a brutal contact between the lower part of the udders and the openings when the pipe is put in place by means of an overhead crane, hence eliminating any risk of damage to the openings and even of all masonry.

The device allowing simultaneously to lower the lower part of the udder and to ensure its rotation increases the ease and the precision of the handling, and thus guarantees the best possible tightness of the connections of the pipes of admission or blowing, on the openings .

Claims (11)

1. Pipe for furnace with chambers intended for the cooking of carbonaceous blocks, this suction or blowing pipe comprising a main body (3) provided with a plurality of nozzles (10) to which tubes called "teats" are connected in number equal to that of the heating partitions (5) constituting the furnace chambers, each of these udders having to adapt to the so-called "opening" openings (8) arranged at the top of each heating partition (5) or of the walls transverse (9) separating the different chambers of the furnace, characterized in that, in order to obtain a tight junction by the alignment in X and in Y, that is to say along the major axis and the minor axis chamber furnace, between each udder and the corresponding opening despite the deformations of the chambers, each udder consists of at least two tubular elements, arranged in series, a first element (15), provided, on the one hand, at its upper part (15a) of a flat flange (18) which cooperates in relation jo intive and in rotation, with a flat flange (19) disposed at the lower part of the nozzle (10), and, on the other hand, at its lower part (15c) with a flat flange (27) parallel to the flange (18) and which cooperates, in contiguous relation and in rotation with a planar flange (26) disposed at the upper part (16A) of the second element (16), the element (15) and the element (16) having over at least part of their height an axis inclined at an angle ex relative to the axis (23) perpendicular to the plane of the flanges. 2. Pipe for chamber furnace, according to claim 1, characterized in that each udder comprises, in addition, a third tubular element (17), in contiguous relation by sliding partial interlocking (33) substantially coaxial, with the lower part (16C ) of the second element (16) and the lower part of which adapts in leaktight relation to the outlet (8). 3. Pipe for chamber furnace, according to claim 1, characterized in that the first element (15) and / or the second element (16) comprise at least a first cylindrical part with an axis perpendicular to the plane of the flanges and a second part cylindrical making an angle 0 (with the axis of the first cylindrical part. 4. Pipe for chamber furnace, according to claim 3, characterized in that the angle o (is determined by its tangent which is equal to the ratio of the maximum eccentricity to be caught, at the height of the inclined part of the element considered. 5. Pipe for chamber oven, according to claim 2, characterized in that the sliding junction (33) between the second (16) and the third (17) element is covered by a sealing bellows (34) resistant to high temperature . 6. Pipe for chamber furnace, according to claim 1, characterized in that the connecting flanges (18) (19), (26) (17) are provided with a sealing means. 7. Pipe for chamber furnace, according to claim 1, characterized in that the connection flanges (18) (19), (26) (27) are supported by counter flanges, respectively (20) (30) and are provided with removable clamping means, such as bolts. 8. Pipe for chamber oven, according to claim 6, characterized in that the seal between the flanges (18) (19), (26) (27) is obtained by injection, into the grease fittings (21) (22) d '' thick grease resistant to high temperature. 9. Pipe for chamber furnace, according to claim 6, characterized in that the seal between the flanges (18) (19), (26) (27) is obtained by a metalloplastic seal. 10. Pipe for chamber furnace according to any one of claims 1 to 9, characterized in that the first element (15) is provided with operating handles (31) to ensure its axial rotation. 11. Pipe for chamber furnace according to any one of claims 1 to 10, characterized in that, in order to achieve both the Y and Z alignment of the elements (16) and (17), the part (16A) of the intermediate element (16A) comprises an operating device in rotation and height, symmetrically formed with respect to the plane passing through the axis (28) by an axis (38) passing diametrically through said element (16A), and supporting at its two ends a disc (37A, 37B) each disc being provided with a radial operating handle (38A, 38B) and connected by a joint (43A, 43B) not coincident with the axis (38), at the upper end of a link (40A, 40B), the l the lower end is connected by a hinge (39A, 39B) fixed on the lower element (17).

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