WO2004079019A2 - 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

 Gas flushing element and associated gas purging device

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 γon non-metallic inclusions in the melt or a desulfurization or dephosphorization, 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.

Accordingly, the invention has the object to offer a gas purging element and an associated gas purging device, which have a high safety standard, a safe and regular

Allow gas supply into the molten metal and άi fully fulfill desired metallurgical functions.

To achieve this object, the invention proposes a refractory ceramic gas purging element for a metallurgical melting vessel having the following sections between a first end to which a gas is supplied and a second end to which the gas is discharged:

- in the first end opens at least one gas supply pipe,

the gas feed pipe opens into a first gas distribution chamber, a plurality of capillary-like channels extend from the first gas distribution chamber as far as a second gas distribution chamber,

- From the second gas distribution chamber extends at least one gas channel, whose cross-section is greater than that of a capillary channel, to the second end of the Gasspülelementes.

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 ₇ from where the gas subsequently flows through several 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 infiltration of molten metal into the gas passages proceed from the second end toward the first end, the second gas distribution chamber serves as a "barrier" to prevent further infiltration of molten metal Has 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. These capillary channels are formed with a significantly smaller flow cross-section than the gas channels 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 be rectilinear but have at least one, preferably a plurality of curved (angled) portions in order 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" the flow path of the gas on the one hand extended, which in principle does not bother, but also prolongs the way for any infiltrating molten metal, which is forced by it 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 with a circular cross-section, so that the overall result for the gas purging element is an outer cylindrical shape. 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 the same possible to vary the cross section from the first to the second end, for example, to reduce, so that a kind of truncated cone 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. in the direction of the enamel ©, 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 greater than the sum of the cross-sectional areas of the subsequent capillary channels in order to form a diffusion space for any penetrating melt and to ensure a gas supply into the capillaries or from the capillaries.

According to one embodiment, the flow cross-section (that is to say the flow-effective cross-section) of a capillary channel is at least 50% smaller than the flow cross-section of a gas feed tube at the first end or the flow cross-section a gas channel at the second end. In this case, the flow cross-section of each capillary channel can also be significantly smaller than the abovementioned 50% relative to the gas feed tube or the gas channels, for example 70, 80 or 90% smaller.

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 the case of gas channels with the aforementioned drop geometry, one embodiment provides for the channels to be arranged "symmetrically" distributed over the cross section: for example, with three channels, the individual channels can be compared to a clock at 6 o'clock, 10 o'clock and 14 o'clock position to be arranged.

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.

Further features of the invention are the subject of the dependent claims and the other application documents.

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

Showing:

FIG. 1 shows a side view of a gas purging element according to the invention,

FIG. 2 shows a section along the line AA according to FIG. 1, FIG. 3 shows an alternative design to the exemplary embodiment according to FIG. 2,

FIG. 4 shows a section along the line B-B in FIG. 1,

5 shows a section C-C in the longitudinal direction in the region of the first end of the flushing element with connected first gas distribution chamber,

FIG. 6 shows a section D-D in the longitudinal direction through the second gas distribution chamber,

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

8 shows a view of a gas purging device with a

Gas flushing element, 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 El in a first section 3, the end face of a steel plate 30 and the periphery of a steel pipe 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 bounded on the circumference 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 gas supply tube 5, as well as the capillary channels 10 and the gas channels 6 are formed by metal tubes, but can also be used in the same way. be formed in situ, for example, during manufacture in that burnt out of their materials with appropriate cross sections are inserted in their place, which are burned out later. This applies analogously to form cavities (Gasverteilkammern) in the ceramic body.

The gas flows from the first end El through the adjoining sections 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 I S, 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

Gas flushing element and associated gas flushing device P atentanspr che A refractory ceramic gas flushing element for a metallurgical melting vessel, comprising successive sections (3, 2, 4, 1) between a first end (El) to which gas is supplied and a second end (E2) at which the gas is discharged becomes: a) In the first end El at least one gas supply pipe opens (5), b) the gas supply pipe (5) opens into a first gas distribution chamber (32); c) from the first gas distribution chamber (32) extend a plurality of capillary-like channels (10) to a second Gas distribution chamber (16), d) of the second Gasverteilkammer (16) extends at least one gas channel (6) whose flow cross section is greater than that of a capillary channel (10) to the second end (E2) of the Gasspülelementes. 2. Gasspülelement according to claim 1, the first and second gas distribution chamber (32, 16) each having a cross section which is greater than the sum of the cross-sectional areas of the capillary channels (10). 3. Gas purging element according to claim 1, wherein the in the first gas distribution chamber (32) opening gas supply pipe (5) has a length which is greater than the axial distance between the first end (El) and the first gas distribution chamber (32). 4. Gas flushing element according to claim 3, wherein the gas supply pipe (5) is helically, helically and / or meander-like bent. 5. Gas flushing element according to claim 3, wherein the gas supply pipe (5) consists of a material which melts at a temperature below the temperature of a metallurgical melt to be treated. 6. Gas flushing element according to claim 3, wherein the gas supply pipe (5) in a bulk material (15) rests. 7. Gas purging element according to claim 1, wherein the capillary channels (10) each have a flow cross section which is at least 50% smaller than the flow cross section of the Gaszuführrohres (5) at the first end (El) and the gas channel (6) at the second end (E2). 8. Gas purging element according to claim 1, wherein the capillary channels (10) each have a flow cross-section which is at least 90% smaller than the flow cross section of the Gaszuführrohres (5) at the first end (El) and the gas channel (6) at the second end (E2). , Gas purging element according to claim 1, wherein the individual, interconnected portions (3, 2, 4, 1) each in a tube (14, 12, 17, 9) made of steel or refractory ceramic material are assembled. 10. Gas flushing element according to claim 1, wherein the sections (3, 2, 4, 1) are assembled in a common tube of steel or refractory ceramic material. 11. Gasspülelement according to claim 1, wherein the one or more gas channels (6) at the second end (E2) have a slot-like, dreieekförmigen or drop-shaped flow cross-section. 12. Gas purging element according to claim 1 having a plurality of gas channels (6) at the second end (E2), which extend at a distance along an imaginary line between the second Gasverteilkammer (16) and the second end (E2). 13. Gas flushing element according to claim 1, which has a circular cross-section over its entire length. 14. Gas flushing element according to claim 13, whose cross-section decreases from the first to the second end (El, E2). 15. Gas purging device with a Gasspülelement according to one of claims 1 to 14 and a drive (M) for the axial and / or rotatable movement of the Gasspülelementes. 6. Gas purging device according to claim 15, wherein the drive (M) is designed for alternating movement of the Gasspülelementes.