EP1599610B1 - Gas bubbling element and corresponding gas bubbling system - Google Patents

Abstract

The invention relates to a refractory ceramic gas bubbling element for a metallurgical crucible and to a corresponding gas bubbling system comprising such a gas bubbling element.

Description

The invention relates to a refractory ceramic Gasspülelement for a metallurgical melting vessel and an associated gas purging with such a Gasspülelement.

Gas flushing elements of the type mentioned have been known for many years. They serve to inject gas, for example argon or nitrogen, into a metallurgical melt. The gas has different purposes: With the gas, the molten metal can be homogenized. In addition, oxidation processes can be accelerated. A goal of the gas treatment may also be the removal of non-metallic inclusions in the melt or a desulphurization or, for example, a molten steel.

Metallurgical melting vessels in which such gas purging elements are used are, for example, pans or ladle furnaces. Gas flushing elements of the type mentioned are also used for the vacuum treatment of a steel.

In this case, the gas is guided in each case between a first end, at which gas is supplied, and a second end, at which the gas is discharged into the melt, along the Gasspülelementes. As a rule, the passage of the gas through corresponding channels.

These channels can z. B. be formed by burnable materials directly in the ceramic material. The channels can also be formed by tubes (tubes) that run in the ceramic material. These channels have different cross-sectional shapes. The flow cross section is, for example, round or slit-like. The channels can run directly, ie axially, but also like a labyrinth from one end to the other end.

In addition, it is known to arrange a so-called breakthrough protection at the first end of the gas purging element or in the gas purging element itself. Such an anti-breakdown device serves to stop infiltration of molten metal into the gas purging element.

Known Gasspülelemente have, for example, a continuous circular cross-section. In addition, truncated cone-like gas purging elements are known, which are used as so-called exchange rinse. The gas purging elements can be used in a refractory framing block. This frame is part of the melting unit, such as an electric arc furnace or a Siemens Martin furnace. These flushing elements are installed in particular in the bottom or the wall of the metallurgical melting vessel. Flushing elements in the bottom can be arranged so that the gas is injected more or less perpendicular to the surface of the soil in the melt. However, it is also known to arrange the flushing elements inclined in order to guide the gas to a certain point within the melt. The same applies to the wall installation of the flushing elements. The installation can be done more or less horizontally, ie perpendicular to the inner wall of the metallurgical vessel or inclined to the horizontal (to the molten bath surface).

The purge gas supply may be continuous or discontinuous. In any case, make sure that the gas flushing device is always functional when needed. This requires appropriate safeguards to z. B. blockages of gas-conducting channels by molten metal or slag to prevent.

In addition, above all, it must be ensured that the above-mentioned breakthrough of the molten metal is prevented.

US Pat. No. 4,539,043 A shows a gas purging element which consists of two separate purging units arranged on top of each other, each purging unit having, in the flow direction of the gas, a gas distribution chamber and adjoining gas passages. The gas channels either all have the same diameter with values between 0.5 and 3 mm or the radially outer gas channels have a smaller diameter than the radially inner gas channels.

In Patent Abstracts of Japan Vol. 1996, no. 05, 31.05.1996, JP 8013019 A, a flushing element is proposed in which the gas inlet side gas channels have a diameter <0.6 mm and the gas outlet side gas channels have a diameter <0.3 mm.

The invention has for its object to offer a gas purging element and an associated gas purging device, which have a high safety standard, allow a safe and regular gas supply into the molten metal and can fulfill the desired metallurgical functions unrestricted.

To achieve this aim, the invention proposes a refractory ceramic gas purging element for a metallurgical melting vessel having the features of claim 1.

Such a gas purging element has the following properties and advantages:

Although the gas purging element is subdivided into several axially adjoining sections, continuous gas delivery is ensured from the first (so-called cold) end to the second (so-called hot) end. Thus, the gas can be introduced via the gas supply pipe in the flushing element. It passes from there into the first gas distribution chamber, from where the gas subsequently flows through a plurality of capillary-like channels in the direction of the second end, before it enters a second gas distribution chamber. From there, the gas is passed through the mentioned larger channels to the second end of the gas purging element and out of this.

Such a gas flushing element has several security features:

Should there be an infiltration of molten metal into the gas channels from the second end towards the first end run, the second gas distribution chamber serves as a "barrier" to prevent the further penetration of molten metal. Characterized in that the gas distribution chamber has a larger cross-section than the sum of the gas channels, the infiltrating molten metal can spread, cool and solidify. Further advancement in the direction of the cold (first) end of the gas purging device is also prevented by connecting capillary channels at the other end of the second gas distribution chamber. Each of these capillary channels is formed with a flow cross-section which is less than half the flow cross-section of the at least one gas channel in the region of the second end, so that in this respect the penetration of molten metal into the capillary channels is made even more difficult.

For example, the gas channels in the region of the second end have an inner diameter> 2 mm or> 3 mm, while the inner diameter of the capillary channels <1.0 mm is selected.

But even if molten metal should flow into and through the capillary channels, the gas purging element according to the invention offers a further securing device through the first gas distribution chamber, in which a similar effect is achieved as already described with reference to the second gas distribution chamber.

Finally, in one embodiment, the invention provides a fourth safeguard. This safety measure is to form the gas supply pipe opening into the first gas distribution chamber with a length greater than the axial distance between the first end of the gas purging element and the first gas distribution chamber. In other words, the gas supply pipe should not run in a straight line, but at least one, preferably a plurality of curved (angled) portions to extend the flow path. In this case, the gas supply pipe may be bent, for example helically, helically and / or meandering. By several "branches" of the flow path of the gas is extended on the one hand, which in principle does not bother, but also extends the way for any penetrating molten metal, which is thereby forced to cool and solidify.

In this case, the Gaszuführrohr may consist of a material which melts at a temperature below the temperature of a metallurgical melt to be treated. Should molten metal penetrate into this area, the gas feed tube would melt. If the gas feed tube, as provided according to a further embodiment, is packaged in a bulk material, then the molten metal can diffuse into this section of the gas purging element, ie branch, whereby the solidification behavior is once more accelerated. It goes without saying that the bulk material must be assembled in a corresponding outer receptacle (for example made of metal or dense ceramic), so that the melt does not diffuse radially in an uncontrolled manner. The receptacle is again surrounded by refractory material.

As far as sections of the longitudinal axis are concerned, they need not be physically separated. The term is much more functional to understand. Thus, the individual sections may have the same cross-sectional shape, for example be formed with a circular cross-section, so that a total for the gas purging element outer cylindrical shape results. The individual sections can be connected to each other. However, all sections can also be assembled in a common refractory matrix. In this case, the gas purging element can have a constant cross section over its entire length, for example a circular cross section. It is also possible to vary the cross section from the first to the second end, for example to reduce, so that a kind of truncated cone shape is formed. In this way, the gas purging element can be used in particular as an exchangeable fluid.

In the case of a constant cross-section, in particular a circular cross-section, it is possible for the associated gas purging device to move and / or rotate the gas purging element in the axial direction. For this purpose, the gas purging device is designed with a corresponding drive. This drive can be designed for alternating axial and / or rotating movement of the gas purging element. For example, the flushing element may be alternately moved axially back and forth by a few millimeters (for example +/- 3 mm) or rotated a few degrees in one direction or the other. The drive can also be used to nachzuschieben the purging element in the axial direction, d. H. to advance in the direction of the melt, for example, when the flushing element is partially worn in the region of the first end.

As already mentioned, the cross-section of the first and second gas distribution chamber should be larger than the sum of the cross-sectional areas of the subsequent capillary channels to a diffusion space for possibly To form penetrating melt and ensure gas supply into the capillaries or from the capillaries.

According to one embodiment, the flow cross-section (ie, the flow-effective cross section) of a capillary channel is at least 70%, 80% or 90% smaller than the flow cross-section of a gas supply tube at the first end or the flow cross-section of a gas channel at the second end.

In one embodiment, the gas channels are slit-like at the second end, i. h., For example, they have a rectangular cross-section. Likewise, the gas channels may be formed with a triangular or drop-shaped flow cross-section. It has proven to be advantageous if the channels (tubes) are arranged with drop-like cross-sectional geometry so that the narrower end of the central longitudinal axis of the Gasspülelementes facing, as shown in the following description of the figures.

The gas distribution chambers can be formed in-situ in the ceramic matrix material of the gas purging element. However, the gas distribution chambers can also be formed by metallic hollow chambers into which the associated gas channels or capillary channels open.

While the capillary channels can be arranged essentially axially, that is to say in parallel and at a distance from one another, the gas passages can be arranged in different ways in the region of the second end of the flushing element:

For example, in gas channels with the aforementioned drop geometry, an embodiment provides to arrange the channels distributed "symmetrically" across the cross section. For example, with three channels, the individual channels can be arranged at the 6 o'clock, 10 o'clock and 14 o'clock positions as compared to a clock.

In another embodiment, especially when gas channels with circular cross-section or slit-like channels are selected, they can run along an imaginary line and at a distance from each other, this line z. B. in a dishwasher, which is installed in a wall of the vessel, runs horizontally.

The channels and chambers are always surrounded by refractory ceramic material (matrix material). This material can be cast or pressed. An outer covering is not necessary. The ceramic flushing element can be installed in this way.

The invention will be illustrated below with reference to various figures, wherein the drawings are purely schematic for better illustration.

Figur 1:

eine Seitenansicht eines erfindungsgemäßen Gasspülelementes,

Figur 2:

einen Schnitt entlang der Linie A-A gemäß Figur 1,

Figur 3:

eine alternative Gestaltung zum Ausführungsbeispiel nach Figur 2,

Figur 4:

einen Schnitt entlang der Linie B-B in Figur 1,

Figur 5:

einen Schnitt C-C in Längsrichtung im Bereich des ersten Endes des Spülelementes mit angeschlossener erster Gasverteilkammer,

Figur 6:

einen Schnitt D-D in Längsrichtung durch die zweite Gasverteilkammer,

Figur 7:

eine Seitenansicht einer Gasspüleinrichtung mit einem Spülelement, welches auf Lagern geführt ist,

Figur 8:

eine Ansicht einer Gasspüleinrichtung mit einem Gasspülelement, welches über einen Antrieb axial bewegbar ist.

Showing:

FIG. 1:

a side view of a gas purging element according to the invention,

FIG. 2:

a section along the line AA of Figure 1,

FIG. 3:

an alternative design to the embodiment of Figure 2,

FIG. 4:

a section along the line BB in Figure 1,

FIG. 5:

a section CC in the longitudinal direction in the region of the first end of the flushing element with connected first gas distribution chamber,

FIG. 6:

a section DD in the longitudinal direction through the second gas distribution chamber,

FIG. 7:

a side view of a gas purging device with a flushing element, which is guided on bearings,

FIG. 8:

a view of a gas purging device with a Gasspülelement which is axially movable via a drive.

In the figures, identical or equivalent components are represented by the same reference numerals.

FIG. 1 shows a gas purging element according to the invention. The structure of the gas purging element (from right to left) is as follows:

A gas supply pipe 5 opens at E1 in a first section 3, the end face of a steel plate 30 and the periphery of a steel tube 14 is limited. The Gaszuführrohr 5 continues behind the steel plate 30 helically, the helix through the Reference numeral 13 is shown. The coil 13 extends in a space which is filled with a bulk material 15, for example based on expanded perlite, and is delimited at a distance from the steel plate 30 by a further steel plate 31, through which the coil 13 is passed.

The steel plate 31 is adjoined by a first gas distribution chamber 32, which is peripherally delimited by the elongated steel tube 14.

In the flow direction of the gas follows a section 2, the cross section of Figure 4 shows. Within a cylindrical frame 12 made of steel (in extension of the tube 14) is a refractory ceramic material in which a plurality of capillary channels 10 extend in the axial direction of the flushing element. The capillary channels (formed by steel tubes) have a circular cross section with an inner diameter of 0.5 mm.

The gas guided via the gas feed tube 5 and the coil 13 via the first gas distribution chamber 32 flows through the capillaries 10 into a subsequent first gas distribution chamber 16 (FIG. 6), which is bounded on the inside by a tubular body 33 which rests in an outer envelope 17. Tubular body 13 and sheath 17 may be made of metal or refractory ceramic.

The gas, which was passed through the second gas distribution chamber 16, then passes into gas channels 6, which in a ceramic matrix material 8 (Figures 2, 3) axially and at a distance from each other extend, to the end face of the second end E2 of Gasspülelementes.

According to FIG. 2, three gas channels 6 with a circular cross-section are arranged along an imaginary horizontal line. Each of the gas channels 6 has an internal cross-section of 2 mm. FIG. 3 shows an alternative embodiment in which three gas channels 6 each have a teardrop shape, the gas channels 6 being arranged at 6 o'clock, 10 o'clock and 14 o'clock, as compared to a clock. The orientation of the gas channels 6 is such that the narrower, more or less triangular-shaped end lies on the inside.

This section 1 of the flushing element is in turn limited by a metal tube 9 circumferentially.

The outer frames (pipe segments) of the individual sections, each consisting of ceramic or metal parts are mechanically connected to each other, wherein the end portions are designed step-like and have corresponding threads. The flushing element shown in Fig. 1 is completely covered with refractory material. It is also possible to assemble the entire gas purging element within a continuous tubular casing or to dispense with the casing entirely. In this case, the gas distribution chambers 16, 32 and the various channels are formed within a ceramic matrix material.

Both the Gaszuführrohr 5, and the capillary channels 10 and the gas channels 6 are formed by metal tubes, but can also in situ be formed, for example, in the production characterized in that in their place ausbrennbare materials are inserted with corresponding cross-sections, which are burned out later. This applies analogously to form cavities (Gasverteilkammern) in the ceramic body.

The gas flows from the first end E1 through the adjoining portions to the gas outlet end, which is marked in Figure 1 with E2.

The function of the flushing element has already been described in the explanation of the invention. It should also be mentioned that the filament 13 here consists of copper, ie a relatively low-melting metal.

According to FIG. 7, the flushing element is guided in the axial direction by a plurality of bearings 18, 19. These are rolling bearings. Via a motor M and a gear 20, the tubular flushing element can be rotated, alternately to the left and right. The drive is located on the outside of the melting vessel.

In the embodiment according to Figure 8, a gear 22 is shown, with the current oscillating movements (eg., Sinusoidal movements) can be transferred to the flushing element to move it in the axial direction, for example, by a few millimeters back and forth.

It is understood that the gas purging element in a corresponding refractory frame in the bottom or the wall of a associated metallurgical vessel must be arranged, in the embodiments according to Figure 7 and 8 so that the rotational movement or axial movement of the flushing element can be ensured. The refractory material of the wall or the bottom of the metallurgical vessel is symbolized in FIGS. 7 and 8 by the reference numeral 35.

Claims (16)

1. Refractory ceramic gas rinsing element for a metallurgical melting vessel, with portions (3, 2, 4, 1) following one another functionally between a first end (E1), at which gas is fed, and a second end (E2), at which the gas is delivered:

   a) At least one gas feed pipe (5) leads into the first end E1,

   b) the gas feed pipe (5) leads into a first gas distribution chamber (32),

   c) a plurality of capillary-like ducts (10) extend from the first gas distribution chamber (32) in the axial direction to a second gas distribution chamber (16),

   d) at least one gas duct (6) extends from the second gas distribution chamber (16) to the second end (E2) of the gas rinsing element,

   e) the capillary ducts (10) in each case have a cross-sectional area of flow which is at least 50 % smaller than the cross-sectional area of flow of the at least one gas duct (6) at the second end (E2).
2. Gas rinsing element according to Claim 1, the first and the second gas distribution chamber (32, 16) of which in each case has a cross section which is larger than the totality of the cross-sectional areas of the capillary ducts (10).
3. Gas rinsing element according to Claim 1, in which the gas feed pipe (5) leading into the first gas distribution chamber (32) has a length which is greater than the axial spacing between the first end (E1) and the first gas distribution chamber (32).
4. Gas rinsing element according to Claim 3, in which the gas feed pipe (5) is bent in a spiral, helical and/or meandering manner.
5. Gas rinsing element according to Claim 3, in which the gas feed pipe (5) consists of a material which melts at a temperature below the temperature of a metallurgical melt which is to be treated.
6. Gas rinsing element according to Claim 3, in which the gas feed pipe (5) lies in a bulk material (15).
7. Gas rinsing element according to Claim 1, in which the capillary ducts (10) in each case have a cross-sectional area of flow which is at least 50 % smaller than the cross-sectional area of flow of the gas feed pipe (5) at the first end (E1).
8. Gas rinsing element according to Claim 1, in which the capillary ducts (10) in each case have a cross-sectional area of flow which is at least 70 % smaller than the cross-sectional area of flow of the gas feed pipe (5) at the first end (E1) or of the gas duct (6) at the second end (E2).
9. Gas rinsing element according to Claim 1, in which the individual portions (3, 2, 4, 1), which are connected together, are in each case assembled in a pipe (14, 12, 17, 9) of steel or refractory ceramic material.
10. Gas rinsing element according to Claim 1, in which the portions (3, 2, 4, 1) are assembled in a common pipe of steel or refractory ceramic material.
11. Gas rinsing element according to Claim 1, in which the gas duct or ducts (6) at the second end (E2) has/have a slot-like, triangular or drop-like cross-sectional area of flow.
12. Gas rinsing element according to Claim 1 with a plurality of gas ducts (6) at the second end (E2) which extend at a spacing from one another along an imaginary line between the second gas distribution chamber (16) and the second end (E2).
13. Gas rinsing element according to Claim 1, which has a circular cross section over its entire length.
14. Gas rinsing element according to Claim 13, the cross section of which decreases from the first to the second end (E1, E2).
15. Gas rinsing device with a gas rinsing element according to any one of Claims 1 to 14 and a drive (M) for the axial and/or rotatable movement of the gas rinsing element.
16. Gas rinsing device according to Claim 15, wherein the drive (M) is designed to move the gas rinsing element in alternating fashion.

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