EP0565690B1 - Nozzle assembly for introducing fluids into a melt, and a method of operating the nozzle - Google Patents

Abstract

PCT No. PCT/EP92/02520 Sec. 371 Date Mar. 2, 1994 Sec. 102(e) Date Mar. 2, 1994 PCT Filed Nov. 3, 1992 PCT Pub. No. WO93/09255 PCT Pub. Date May 13, 1993.To increase the service life of a tuyere arrangement for the introduction of agents into a molten bath, comprising an apertured block (3) refractory material which can be fitted into the wall (1) of a vessel (12) and which includes a cylindrical body (4) with an inserted tuyere tube (6,7), the cylindrical (4) is axially displaceably fitted in the apertured block (3) the tuyere tip which is consumed is replaced by a follow-up movement of the cylindrical body (4).

Description

The invention relates to a nozzle device for introducing media into a melt according to the preamble of claim 1. Furthermore, it relates to a method for operating this nozzle device.

A nozzle device of this type has become known from DE-C2-38 09 828. The known device for introducing gases and / or solid reaction substances and additives into a metallurgical melting vessel contains a perforated brick inserted into the wall of the melting vessel which axially displaceably receives a flushing brick which has at least one gas duct which can be connected to a gas line. The outlet opening of the gas channel is provided on the circumferential surface of the sink block so that it is only released and the media can be introduced into the melt when the sink block is advanced with its inner end over the annular end face of the perforated block. By pulling back the purging plug, a closure is ensured without the need to apply a continuous gas pressure to the purging system, so that the nozzle device is particularly suitable for transport vessels, such as a pan, in which it is not possible to use the gas purging system over the entire residence time of the melt to supply gas in the vessel. The axial displacement of the flushing stone thus serves the task of being able to use it not only for introducing media but also as a closure member.

From DE-C-23 24 0 86, a nozzle for introducing fresh gas, in particular oxygen, has become known through the wall of a fresh vessel below the bath surface, in which the fresh gas is passed through an inner tube and through a concentric one A protective medium can be passed into the outer tube into the melt and the two tubes are arranged concentrically in a stationary jacket tube. The inner and outer tubes are axially displaceable and interchangeable, each spaced in at least one jacket tube.

In this way, at least one additional annular space is created for introducing a protective medium, and there is the possibility of changing the inner and outer tubes between two batches or moving them axially to influence the masonry wear in the immediate vicinity of the nozzles. In the event of a funnel formation due to wear in the area of the outlet opening of the nozzle device, the inner and outer tubes can be advanced and the funnel can then be filled, for example by spraying or tamping.

EP-B1-0 182 965 discloses a method for protecting a nozzle from at least three concentric tubes, through which a central channel and at least two ring channels are formed, in which an oxygen-containing gas and an annular channel pass through the central channel a mist of atomized water is blown in as the cooling fluid, the atomization of the water being carried out by means of a carrier gas in a nozzle head on the inlet side of the nozzle. This cooling fluid has proven to be particularly effective in increasing the service life of the nozzle.

GB-A-2 140 142 discloses a gas purging arrangement with a metallic or ceramic tube which is axially displaceable within a perforated brick. The tube can consist of several tube sections screwed or otherwise connected and contain gas-permeable inserts which are firmly inserted into the tube and are axially displaceable together with it. The outer surface of the tube is preferably covered with a refractory lubricant layer, for example made of graphite.

When the bottom of the vessel has been removed to such an extent that it has to be separated, the metallic or ceramic tube, including the inserts, is pushed into the interior of the furnace, refractory mass 19 stamped and then put the nozzle device back into operation. Here, the uppermost tip of the nozzle, which is closed by solidified metal, is washed away when the new melt is introduced and the nozzle arrangement is brought into its functional state.

US-A-3,829,073 describes a nozzle device with two spaced apart concentric tubes, the outer of which is embedded in a filling material made of refractory material, which is stamped between the outer tube and a tubular casing. In order to prevent the hydrocarbons introduced as cooling gas through the annular gap between the two tubes of the nozzle device from escaping through the ramming mass enveloping the outer tube and being able to ignite outside the furnace vessel, the ramming mass is subjected to an overpressure from the outside.

GB-A-1 152 330 discloses a nozzle device with two concentric steel tubes spaced apart. A reactive gas, such as oxygen, is optionally mixed with an inert gas through the central channel and an inert gas is introduced through the ring channel between the two concentric tubes to protect the nozzle tip. The outer of the two concentric pipes is cemented into a perforated brick using a filling material made of refractory material.

After the end of the fresh process, the gas flows introduced through the nozzle are switched off. The metal melt penetrating into the nozzle tip solidifies inside the nozzle and the latter is replaced by a new nozzle after the liquid metal has been tapped from the vessel.

US-A-4,449,701 describes a non-displaceable nozzle device projecting over the inner wall of the furnace, for blowing in a non-oxidizing gas, from two concentrically spaced pipes, the inner pipe being filled with refractory material and through the annular gap between the inside - and the Outer tube gases are introduced. The distance between the inner and the outer tube is determined by suitable helically arranged spacers.

The object of the invention is to increase the service life in a nozzle device for introducing media into a melt, to shorten the downtimes and to simplify the maintenance work. Furthermore, a method for operating this nozzle device is to be specified.

The nozzle device according to the invention is characterized by the features of claim 1, the method according to the invention by the features of claim 11.

In the nozzle device according to the invention, both the consuming tip of the nozzle tubes and the refractory material surrounding this tip are replaced either continuously or periodically by re-inserting the sleeve containing the metallic nozzle tube or the metallic nozzle tubes. Since the nozzle is intended for use below the bath level of the melt, in addition to the axial displaceability of the sleeve, it must also be ensured that no melt can penetrate into the annular gap between the surfaces to be displaced relative to one another. This is made possible by covering the sleeve with a thermally resilient lubricant layer, providing an annular gap between the outside of the sleeve and the inside of the perforated brick and sealing it with a cement layer. In this way, with an axially displaceable sleeve, a permanent seal between the sliding surfaces can be achieved even for a low-viscosity melt, such as a lead melt at temperatures of approximately 1200 ° C. Since the nozzle tip is exposed to temperatures between 1000 and 2000 ° C, depending on the area of application, it is essential that not only the cement layer sealing the annular gap but also the lubricant layer which enables the axial displacement is thermally resilient. In addition, the material of the lubricant layer should have only a very low tendency towards wetting compared to the adjacent cement layer. In the case of a cement layer based on magnesite or magnesite-chromium, graphite and molybdenum compounds have proven to be particularly advantageous as the material for the lubricant layer.

At the beginning of the use of the nozzle device, the sleeve protrudes a substantial amount on the outside of the perforated brick. Pushing the sleeve receiving the metallic nozzle tube together with the nozzle tube has problems, namely damage to the sleeve, because of the different bending elasticity of metal and ceramic when the sleeve is subjected to buckling loads. It has been shown that the difficulties can be overcome if the metallic nozzle tube is not inserted firmly into the bore of the sleeve but is axially displaceable. For this purpose, the outside of the nozzle tube adjacent to the inside of the sleeve is covered with a thermally resilient lubricant layer, an annular gap is provided between this outside of the nozzle tube and the inside of the sleeve and this is sealed with a cement layer. In this way, the transmission of axial forces between the outside of the nozzle tube and the inside of the sleeve is reduced and the risk of damage to the sleeve when being pushed is reduced.

While the lubricant layers on the outer surface of the sleeve or on the outer surface of the outer nozzle tube are applied either before insertion either into the perforated brick or into the sleeve, the cement layer for sealing the respective annular gap after the sleeve has been introduced into the perforated brick or the nozzle tube pressed into the sleeve. For this purpose, radial bores for pressing cement are provided in the perforated brick or in the sleeve approximately in the middle of their axial length.

Although the service life of the nozzle device can already be significantly increased by the continuous or periodic replacement of the nozzle tip, a further increase in the service life is possible if, in addition to the treatment media, such as oxygen, coal dust etc., a cooling fluid is also introduced. In this case, the lowering of the temperature along the sliding surfaces between the perforated brick and the sleeve or sleeve and the outer nozzle tube also maintains the mutual displaceability for longer.

In a nozzle device with a nozzle tube inserted into the sleeve, the cooling fluid can be introduced, for example blown in, together with the treatment agent. However, it is particularly advantageous, particularly because it is a independent control of the cooling is possible if a nozzle device is used, in which at least two concentric, metallic nozzle pipes are inserted into the sleeve, which form a central channel and at least one ring channel surrounding the central channel, the treatment agent and then through a channel another channel the cooling fluid is introduced. A particularly effective cooling is achieved if a mist of atomized water is supplied as cooling fluid to a channel, in particular the outer ring channel. By evaporating the small water droplets contained in the spray mist within the channel and by dissociation when it is introduced into the melt, intensive cooling is achieved both over the entire thermally stressed length of the sleeve and at the nozzle tip, which, in connection with the re-feeding of the sleeve, leads to unexpectedly high levels Downtimes.

In order to reduce the stress on the end face of the perforated brick facing the inside of the vessel, it is advisable to have the sleeve protrude from the perforated brick into the melt by a certain protrusion, for example in the order of magnitude of 100 mm. The desired projection can be maintained by pushing the sleeve.

The nozzle device can be used with different melts, in particular such as metal melts, iron melts and lead melts. Due to its dimensions, it can also be adapted to the media to be introduced, which can be gaseous, liquid, pasty or dusty.

Fig. 1

im Längsschnitt eine erste Ausführungsform einer Düseneinrichtung,

Fig. 2

in vergrößerter Darstellung den Schnitt II-II von Fig. 1,

Fig. 3

im Längsschnitt einen Teil einer weiteren Ausführungsform einer Düseneinrichtung und

Fig. 4

die rechte Seitenansicht der Düseneinrichtung nach Fig. 3.

The invention is explained in more detail by two exemplary embodiments with reference to four figures. Show it:

Fig. 1

in longitudinal section a first embodiment of a nozzle device,

Fig. 2

in an enlarged view the section II-II of Fig. 1,

Fig. 3

in longitudinal section part of a further embodiment of a nozzle device and

Fig. 4

the right side view of the nozzle device of FIG. 3rd

The nozzle device shown in FIGS. 1 and 2 contains a perforated brick 3 made of refractory material that can be inserted into the wall 1 of a vessel 2. The wall of the vessel can be the bottom wall or the side wall of the vessel. The perforated brick is to be used in such a way that the medium introduced through the nozzle device is fed to the melt below the bath level.

The perforated brick 3 axially slidably receives a sleeve 4 made of a refractory mass, which has an axial bore 5. In this, two concentric metallic nozzle tubes 6 and 7 are inserted at a distance from one another, which form a central channel 8 and an annular channel 9 surrounding the central channel. These channels are connected at the outer end of the nozzle tubes with connections 10 and 11 for the media to be introduced. The sleeve 4, including the nozzle tubes 6 and 7, with its nozzle tip pointing into the interior of the vessel, that is to say with its inner end, protrudes beyond the inner end face 12 of the perforated brick 3, extends through the perforated brick 3 and stands with its outer End by a substantial amount, which in the case shown corresponds approximately to the length of the perforated brick from the outer end face 13 of the perforated brick 3. The outer end of the sleeve 4 is provided with a first pressure plate 14 which is guided by guide rods 15 fastened to the housing wall and running parallel to the sleeve 4. 16 with a flange is designated which carries the guide rods 15 and on the outer steel jacket 17 of the furnace vessel 2 is attached. The flange 16 also carries a sealing device 18.

The outer ends of the concentric nozzle tubes 6 and 7 are fastened in a nozzle head 19, which has a second pressure plate 20 on its outer end face, which is non-positively connected to the first pressure plate 14. This second pressure plate 20 is also guided by the guide rods 15.

2, the sleeve 4 is coated with a lubricant layer 21 and an annular gap between the outside of the sleeve 4 and the inside of the perforated brick 3 is sealed with a cement layer 22. The lubricant layer 21 is applied before the sleeve 4 is inserted into the perforated brick 3. This can be, for example, a cover layer made of sliding material, such as a molybdenum compound, firmly attached to the sleeve 4. The sliding layer can also be applied to the sleeve 4 in the form of a film immediately before it is inserted. In order to introduce the sealing cement layer 22, a radial bore 23 is provided in the perforated brick 3, through which the cement layer is pressed. The thickness of the annular gap that is to be filled by the sealing cement layer must be chosen so that the layer pressed in via the radial bore 23 can penetrate to the end faces 12 and 13 of the perforated brick. With the usual dimensions, a value of 0.5 to 1 mm has proven to be expedient as the thickness for the annular gap to be filled through the cement layer.

The inner nozzle tube 7 is held at a distance within the outer nozzle tube 6 by spacers, not shown, to form the annular channel 9. It must be ensured that the spacers do not significantly impair the media flow through the ring channel 9.

The outer tube 6 is inserted into the sleeve 4 so that, on the one hand, there is a tight seal between the outside of the outer tube and the inside of the sleeve, but on the other hand slight longitudinal displacements between the sleeve and the outer tube are possible, i.e. the transmission of axial forces at the interface between the sleeve and the outer tube is largely avoided. For this purpose, a lubricant layer 25 is applied to the outer tube 6 - this can be a solid coating applied during the manufacture of the tube or a coating applied before the tube is inserted - and it becomes at least after the tubes 6 and 7 have been inserted a provided in the sleeve 4 radial bore 26, a cement layer 27 for sealing an annular gap between the outer tube 6 and sleeve 4 is pressed.

A magnesite-phosphate compound is preferably used for the treatment of an iron melt, a magnesite-chromium compound is preferably used for the treatment of a lead melt, and a magnesite-silicon compound is preferably used for the treatment of a glass melt.

When using the nozzle device for blowing a treatment agent, such as oxygen or coal dust, into a steel bath, a line for the supply of oxygen gas or pulverized coal suspended in a carrier gas is connected to the connection 10 which is connected to the central channel 8 of the inner nozzle tube 7 and a line for the supply of a cooling fluid, preferably a mist of atomized water, to the connection 11 connected to the ring channel 9. The water can also be atomized by means of an atomizing device provided in the nozzle head 19, as described, for example, in EP-182 965.

If the nozzle tip protruding into the melt has burned back a little due to the thermal and mechanical stress, an axial pressure on the second pressure plate 20 (see arrow 29) and due to the non-positive connection between the first and second pressure plates 14 and 20, the sleeve 4 together with the nozzle tubes 6 and 7 is pushed inwards by a corresponding amount and thus replaces the used nozzle tip. This can take place at certain time intervals, as a result of which the service life is significantly increased compared to a nozzle device without this possibility of displacement. Due to the cooling of the sleeve and the perforated brick surrounding the sleeve through the cooling fluid guided through the outer annular channel 9 over the entire length of the sleeve, not only is its displaceability ensured over a longer period of time, but also the life of the nozzle device is further increased. Compared to known nozzle devices, significantly longer service lives can be achieved, the replacement of the refractory material used on the thermally and mechanically most stressed nozzle tip being possible by pushing the sleeve 4 without interrupting the treatment process of the melt.

The nozzle device shown only partially in FIGS. 3 and 4 contains a conical perforated brick 3 and only one nozzle tube 6. For the parts corresponding to the first nozzle device according to FIGS. 1 and 2, the same reference symbols have been chosen. Reference is made to the description of these parts relating to the first exemplary embodiment.

The nozzle device according to the second exemplary embodiment has been used for the oxidation of lead ores and for the reduction of lead oxide slag in order to form metallic lead. The treatment process is divided into two sections, namely an oxidation section and a reduction section.

The oxidation section produces slags with a high iron oxide and lead oxide content. The working temperature is between 1000 and 1100 ° C. This is the section with the higher nozzle wear.

In the reduction section there are operating temperatures between 1200 and 1300 ° C, the slag has a low lead oxide content, namely about 2% and contains about 20% iron oxide.

It has been shown that chromium-magnesite stones have a longer service life than magnesite stones. For this reason, chrome magnesite is used both for the consecutive perforated brick 3 and for the sleeve 4. The treatment agent is introduced through the central channel of the nozzle tube 6.

Claims (14)

1. A nozzle assembly for introducing media into a melt,

   comprising a perforated nozzle brick (3) of refractory material insertable into the wall (1) of a vessel (2),

   which axially displaceably receives a cylindrical body of a refractory compound with an axial bore (5) for introducing the gas or the treatment agent,

   which, relative to the nozzle tip pointing into the interior of the vessel in the installed state, projects out of the perforated nozzle brick (3) with its opposite outer end, and is provided at this end with a first pressure plate (14) for axially displacing the body,

   with the proviso that

   the cylindrical body is designed as a sleeve (4) into which at least two concentric, metallic nozzle tubes (6, 7) are inserted which form a central channel (8) and at least one ring channel (9) surrounding the central channel, and that these channels are connected at the outer end of the nozzle tubes with connections (10, 11) for the media to be introduced.
2. A nozzle assembly according to Claim 1, characterised in that the sleeve (4) is covered with a thermally stressable lubricant layer (21) and an annular gap between the outside of the sleeve (4) and the inside of the perforated nozzle brick (3) is sealed with a cement layer (22).
3. A nozzle assembly according to one of Claims 1 to 2, characterised in that the sleeve (4) has on its outside axially extending longitudinal ribs which are distributed across the periphery of the sleeve.
4. A nozzle assembly according to one of Claims 1 to 3, characterised in that the outside of the nozzle tube (6) which is adjacent to the inside of the sleeve (4) is covered with a thermally stressable lubricant layer (25) and an annular gap between this outside of the nozzle tube (6) and the inside of the sleeve (4) is sealed with a cement layer (27).
5. A nozzle assembly according to one of Claims 1 to 4, characterised in that the perforated nozzle brick (3) and/or the sleeve (4) has or have approximately in the centre of its or their axial length a radial bore (23 and/or 26) for squeezing in cement.
6. A nozzle assembly according to one of Claims 1 to 5, characterised in that the outer end of the nozzle tube (6) or the outer ends of the nozzle tubes (6, 7) is or are attached in a nozzle head (19), which has on its outer end face a second pressure plate (20) which is connected non-positively to the first pressure plate (14).
7. A nozzle assembly according to one of Claims 1 to 6, characterised in that the pressure plate(s) (14, 20) is or are guided by guide rods (15) attached to the housing wall and extending parallel to the sleeve.
8. A nozzle assembly according to one of Claims 1 to 7, characterised in that the refractory material of the perforated nozzle brick (3) and/or of the sleeve (4) consists predominantly of magnesite or chromium magnesite.
9. A nozzle assembly according to one of Claims 1 to 8, characterised in that the lubricant layer (21, 25) consists predominantly of a graphite paste, a molybdenum compound, soapstone or tallow.
10. A nozzle assembly according to one of Claims 1 to 9, characterised in that the cement layer (22, 27) consists predominantly of a magnesite-phosphate, a magnesite-chromium or a magnesite-silicon compound.
11. A method for operating a nozzle assembly according to one of Claims 1 to 10, which is inserted into the wall (1) of a vessel (2) holding a melt and through which media are introduced beneath the bath level of the melt, characterised in that the consumed nozzle tip is replaced continuously or at intervals over time by subsequently pushing the sleeve (4) together with the nozzle tube or tubes (6, 7) into the interior of the vessel.
12. A method according to Claim 11, characterised in that a projection (a) across the inner end face (12) of the perforated nozzle brick (3) is always maintained by subsequently pushing in the sleeve.
13. A method according to Claim 11 or 12, characterised in that a cooling fluid is introduced through one of the channels (9), in particular the outer ring channel.
14. A method according to Claim 13, characterised in that a mist of atomised water is supplied to the channel (9) as cooling fluid.

Images