EP0480856B1 - Installation for descaling a lance, which will be introduced into a metallurgical vessel - Google Patents

Abstract

This device comprises a fixed support constituted by a cylindrical collar 14, through which the lance 5 may be axially displaced and scraping fingers 16 whose extremities, which comprise cleaving means 21, may be held substantially in contact with the lance. A clearance is arranged, between the lance and the collar, which is sufficient to allow the accretions 12 of materials which it is desired to remove from the lance to pass through. While the lance is being raised, the extremities of the fingers cleave the accretions until they are totally broken off from the lance and can then fall into the vessel. The device is particularly applicable to the unclogging of oxygen lances used in steelworks converters.

Description

The present invention relates to the field of steelworks converters equipped with oxygen lances, and more particularly the cleaning of these lances in order to remove the clashes of materials which occur on their external surface during their use.

It is known that during the operation of such a converter, the injection of oxygen by the lance can cause strong projections of slag or metal which adhere to the barrel thereof and clog it. These projections can accumulate and form a gangue called "wolf" partially or completely coating the barrel of the lance. To prevent this wolf from becoming too large and risk hindering the ascent of the lance or even damaging the guide shaft of the lance, it is necessary to regularly clean the lance barrel.

Document LU 86 624 discloses a lance barrel cleaner in a fixed position in the workshop to which the lance is sent during its repairs after use in the converter. This device, relatively imposing by its size and mechanically complex, comprises two scraper tips at 120 ° serving as support for the lance barrel, but articulated around a vertical axis to ensure self-centering. A third scraper tip at 120 ° from the other two is mounted, it pivots around a horizontal axis secured to an autonomous support structure.

Also known, from document GB 2 067 259, is a cleaner with pivoting knuckles about horizontal axes and deviating upwards under the control of jacks, the whole being mounted floating on the superstructure of the converter to allow self-cleaning. centering on the lance, it remains operational during its cleaning.

Likewise, document FR-A-2 214 752 describes a device making it possible to provide this cleaning automatically when the lance is raised. This device consists of a fixed support guiding the lance and provided with scraping fingers distributed around the lance.

These fingers, whose lower end in contact with the lance is configured in the form of a ploughshare, are used when raising the lance, to split and spread the wolf, to facilitate its detachment from the lance. Despite this splitting of the wolf, snags can remain in the areas of the wall of the lance located between two fingers, and come up against the support which ultimately causes them to be torn off, but at the cost of a sharp increase in the ascent effort of the spear.

The object of the present invention is to reduce these forces which risk damaging the lance or the support, and requires oversizing the holding and driving members of the lance.

With these objectives in view, the invention relates to a device for cleaning a lance intended to be introduced from above into a metallurgical container, such as a blowing lance of a steelworks converter, of the type comprising a fixed support which comprises an orifice through which the lance can be moved axially and scraper fingers distributed around this orifice and the ends of which, which can be kept substantially in contact with the external wall of the lance, include means for splitting arranged so as to split materials hung on the wall of the lance when it exits from said container.

According to the invention, this device is characterized in that said orifice of the support has dimensions greater than those of the section of said lance, so as to provide between the latter and the support a clearance sufficient to allow free passage of said materials attached to the wall of the lance, in that the fixed support is surmounted by a frustoconical ferrule flaring upward so as to form a funnel, and in that the fingers are retractable towards the periphery of the orifice, and pivoting around pivots linked to a cylindrical shell constituting the support, and provided with return means for returning them to a working position where they extend radially towards the center of the orifice, stops preventing the pivoting of the fingers upwards beyond said working position.

According to a particular arrangement, the fingers retract through windows made in the shell. According to another particular arrangement, sealing means are provided to prevent the passage of smoke or dust through these windows. These sealing means may consist of one or more cowlings covering these windows from the outside of the support, or of an injection of a gaseous fluid into these windows. Such an injection creates a gaseous sealing curtain which does not disturb the movement of the fingers. In addition, the injected gas jet prevents dust from settling in the windows and on the fingers, and thus ensures freedom of movement of the latter.

The scouring device according to the invention allows, thanks to the clearance provided between the support and the lance, the passage of the hooks, split but not completely separated from the lance, between the scraper fingers, in the orifice of the support, thus avoiding that these remaining clashes abut in said support and thus eliminating the effort which would otherwise be necessary to tear off the clashes and continue the withdrawal of the lance. By cons when, as a result of the upward movement of the lance, these hooks are split over their entire height, they detach from the lance without difficulty.

• la figure 1 est une vue schématique d'ensemble d'un tel convertisseur, représenté en phase d'affinage ;
• la figure 2 est une vue de détail en perspective du dispositif de décrassage conforme à l'invention, lors d'une phase de remontée de la lance ;
• la figure 3 est une vue correspondante lors de la descente subséquente de la lance ;
• la figure 4 est une vue de dessus du dispositif.
• la figure 5 est une vue similaire à celle de la figure 3 dans le cas d'une variante du dispositif.

Other characteristics and advantages will emerge better from the description which will be given by way of example of a scouring device according to the invention, for cleaning an oxygen blowing lance in a steelworks converter. . Reference is made to the appended drawings in which:

• Figure 1 is a schematic overview of such a converter, shown in the refining phase;
• Figure 2 is a detailed perspective view of the scouring device according to the invention, during a phase of raising the lance;
• Figure 3 is a corresponding view during the subsequent descent of the lance;
• Figure 4 is a top view of the device.
• Figure 5 is a view similar to that of Figure 3 in the case of a variant of the device.

In Figure 1 is shown a steelworks installation comprising a converter 1 surmounted by a cover skirt 2 connected by a fume extraction hood 3 to a chimney 4. A cooled blowing lance 5 enters the converter substantially vertically passing through a well 6 lance linked to the hood. This lance is supported by a carriage 7 guided by guide rails 8 and can be moved vertically by drive means, not shown.

The installation is shown in FIG. 1 in the refining phase of the molten steel 9 contained in the converter, the lance then being in the low position and oxygen 10 being blown towards the steel bath. Under the effect of this jet of gas, the steel bath 9 surmounted by slag 11 is violently stirred and projections of slag and metal are deposited and cling, solidifying on the wall of the lance where, in s 'accumulating, they lead to the formation thereon of a wolf 12. This wolf is therefore formed of hooks of solidified metal and slag, which can cover the entire circumference of the lance over a significant height. The problem posed by the presence of this wolf is that, if it is allowed to grow excessively, not only does it constitute an overload for the device for supporting the lance, but also there is a risk of damaging the well of the lance or the lance itself during the ascent of the latter, or even there is a risk of not being able to extract the lance from the converter, the wolf being trapped in the well. It is therefore necessary to free the lance from these hooks, which is achieved by the device according to the invention, which will now be described in connection with Figures 2 to 4, as well as its operation.

This device is located in the installation described above, at the level of the lance well. The device therefore comprises a support constituted by a cylindrical ferrule 14, rigidly fixed to the lance well, and surmounted by a frustoconical ferrule 15 in the form of a funnel. The inside diameter of the cylindrical shell is much greater than that of the lance so as to provide sufficient clearance between them to allow the passage of the hooks 12. For example, the diameter of the lance may be 450 mm and that of the shell of 900 mm. Radial and angularly distributed scraping fingers 16 are pivotally mounted on pivots 17 of horizontal axis linked to the cylindrical shell 14, so as to be able to pivot in a vertical radial plane. In a working position, represented in FIG. 2, these fingers extend substantially radially towards the center of the orifice defined by the cylindrical shell, practically until contact with the lance; in other words the length of these fingers is determined so that in this position, they leave between them sufficient free space to allow the free passage of the lance when the latter is devoid of any attachment.

The fingers 16 are provided with a return means in this position, here counterweights 18. Furthermore a stop 19 is provided for each finger to prevent pivoting upwards beyond their working position.

By pivoting downwards, the fingers can be retracted so as to clear the interior of the ferrule 14. Preferably, in order to be able to completely free this space, the pivots 17 of the fingers are mounted in windows 20 formed in the wall of the shell so that the fingers have the possibility of being fully retracted in these windows.

At their ends, the fingers carry splitting means, which can be produced for example in the form of knives 21, the cutting edge of which is directed downwards. In the working position, these knives are substantially at the level of the pivots of the fingers. The slight clearance 22 formed between the end of the fingers and the lance avoids marking the lance in the event of a slight offset, if any.

The operation of the device is as follows: When, after the blowing phase, we want to raise the lance, we control the drive means of the carriage 7 which move the lance upwards. It passes freely between the fingers 16, which are held by the counterweights 18 in their working position, as long as no hooking abuts the ends of said fingers.

When the wolf 12 formed by these hooks arrives at the level of the fingers, due to the continuation of the upward movement of the lance, the knives 21 carried by the ends of the fingers begin to split the wolf vertically, as shown in FIG. 2. This splitting tends to cause the spacing of the portions 12 'of the split wolf and their detachment from the lance. But these wolf portions remain integral with the lower part of the wolf 12 and, although detached from the lance, they continue to accompany it in its movement. Thanks to the large clearance between the lance and the cylindrical shell 14, they pass freely on the other hand inside the latter.

As the lance continues its upward movement, the wolf's splitting continues to its lower end. The split portions of wolves, peeled off the lance and then having no connection between them, detach from the lance and by their weight fall in the free space between the lance and the ferrule 14, and fall back into the converter. The fall of these portions is facilitated by the fact that the fingers, no longer being then subjected to the splitting force which kept them in the working position against the stops 11, can be retracted by pivoting under the sole weight of the portions of Wolf.

It will be noted that the frustoconical shell 15 advantageously serves as a funnel for collecting the wolf portions when they detach from the lance, and directing them towards the free space of the shell.

It will be easily understood that the effort of raising the lance necessary to clean the lance is, thanks to the invention considerably reduced compared to that which is necessary in the use of prior art devices, such as that described at the beginning of this brief. In fact, in these devices, the hooks are sort of scraped over the entire periphery of the lance, which despite the prior splitting, results in strong resistance to the ascent of the lance. Contrary to this, the use of the device according to the present invention creates, during the ascent of the lance, only the force necessary for splitting. The device can thus be considerably reduced, and moreover the risks of damage to the lance are reduced.

It will also be noted that, in the event that snags have remained adherent to the lance after its ascent, for example 12 "snaps which would have passed between the fingers of the device without being peeled off, the extra thicknesses thus created would not hinder the subsequent descent of the spear, since they would repel the fingers when they passage in the device, as shown in Figure 3.

The invention is not limited to the particular device which has just been described solely by way of example. In particular, the scraping fingers could be mounted under the cylindrical shell. The counterweights can also be replaced by elastic return means, for example springs and the finger stops can be constituted by any stop means preventing the pivoting of the fingers upwards beyond their working position. Likewise the ferrule 14 can constitute in itself the lance well.

The shape of the fingers can also be changed. For example, to increase their rigidity, these can be constituted as shown in FIG. 5 by plates 16 ′ carrying, at the corresponding location of the fingers described above, the knives 21, and of which a portion 18 ′ in extension towards the outside of the shell constitutes the counterweight. The configuration of the fingers can be modified insofar as, on the one hand, they cannot interfere with the lance whatever their position, and on the other hand their ends carrying the knives are in their position closest to the launches, when said fingers are in abutment, in the working position.

In the variant shown in Figure 5, the device comprises sealing means of the windows 20, constituted by pipes 23 opening into said windows by nozzles 23 '. These pipes are connected to hollow rings 24 surmounting the ferrule 14, and connected to supply means, not shown, in a gaseous fluid under pressure, such as water vapor or nitrogen. These rings have their internal wall 25 pierced with a plurality of orifices 26 by which the gaseous fluid escapes into the shell. Thus the gaseous fluid issuing from the orifices 26 and 23 ′ creates a gaseous sealing curtain both between the vortex and the lance, and in the windows 20.

The sealing of the windows 20 can also be achieved by the installation of cowlings, not shown, covering either each window respectively, or all of the windows, these cowlings being fixed to the shell in a sealed manner and of such shapes and dimensions that they do not disturb the movement of the scraping fingers.

Note also in the variant of Figure 5, an extension 27 of the frustoconical shell 15, intended to facilitate the collection and guidance of the wolf pieces detached from the lance.

Claims (6)

1. Device for unclogging a lance (5), such as a blast pipe of a steelworks converter, intended to be inserted from above into a metallurgical vessel (1), of the type comprising a fixed support (14) which comprises an orifice through which the lance may be axially displaced and, distributed around this orifice, scraping fingers (16) whose extremities, which may be held substantially in contact with the external wall of the lance, comprise cleaving means (21) set up in such a manner as to cleave materials (12) accreted on the wall of the lance while the latter is extracted from the said vessel, characterised in that the said orifice of the support has dimensions greater than those of the cross-section of the said lance, in such a manner as to arrange a clearance, between the latter and the support, sufficient to allow the said materials accreted on the wall of the lance to pass through freely, in that the fixed support is surmounted by a frustoconical collar flaring upwards, in such a manner as to form a funnel, and in that the fingers (16) are able to retract towards the periphery of the orifice, and can pivot about pivots (17) connected to a cylindrical collar (14) constituting the support and fitted with return means (18) to return them to a working position in which they extend radially towards the centre of the orifice, abutments (19) preventing the fingers from pivoting upwards beyond the said working position.
2. Device according to Claim 1, characterised in that windows (20) are arranged in the collar (14), the pivots (17) of the fingers being mounted in these windows in such a way that the fingers may be retracted inside the latter.
3. Device according to Claim 1, characterised in that the fingers carry at their extremities cleaving means (21) such as knives whose cutting edge is oriented downwards.
4. Device according to Claim 1, characterised in that it comprises means for sealing the windows (20).
5. Device according to Claim 4, characterised in that the sealing means comprise means (23, 23') for injecting a gaseous fluid into each window.
6. Device according to Claim 5, characterised in that the injection means are connected to means for supplying steam or nitrogen.

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