EP0772695B1 - Gas flushing device in the blowpipe of a vacuum degassing vessel - Google Patents

Description

The invention relates to a gas purging device for a a refractory lined trunk Degassing vessel.

DE 39 11 881 C1 is a fired gas purging plug known in the side wall of an evacuation vessel in Area of the molten steel is installed. This is what it is about a discrete gas purging element.

In "Radex-Rundschau, Issue 4, 1990, 365" the development of gas purging elements for degassing vessels. In this it is mentioned that in a typical plant with six to twelve tubes of 3 or 4 mm in diameter each Inlet nozzle of the vacuum vessel is rinsed.

In the "Radex-Rundschau, issue 4, 1992, 171" a RH method shown, in which argon in the inlet trunk is blown through 3 to 4 mm thick steel tubes.

With the RH (Ruhrstahl-Heraeus) process, the liquid Steel from a ladle in a riser with the help a conveying gas, in particular argon, above the steel bath level is inserted into the riser, through the Volume increase in the riser pipe and further by the Pressure difference between the outside air pressure and the Vacuum in the evacuation vessel transported into this. The in the evacuation vessel is sprayed with steel, which causes a large increase in surface area and thus a good degassing occurs. Introduced at the same time Oxygen that is under during the entire treatment period other is supplied from the slag leads to Formation of carbon monoxide, which outgasses in the vacuum vessel, with what the desired decarburization is achieved.

Attempted by blowing in additional oxygen fine decarburization to the lowest possible values optimize.

A quick decarburization process is particularly possible through a high circulation speed of the melt and thus a Increase in the conveying gas flow and an increase in Trunk diameter of the vacuum system reached.

EP 0 297 850 A1 describes a method and a device for degassing molten metal as part of an RH process described. There are several in the proboscis Channels circumferentially arranged in two groups be divided into one group with gas under high Pressure and a group with gas under low pressure is applied. In this way, the fed Gas flows at different depths through the proboscis guided metal melt penetrate and a uniform Fumigation of the molten metal over the trunk cross-section enable.

From Patent Abstracts of Japan vol. 011 no.141 (C-421), 8. May 1987 & JP, A, 61 281811 is a proboscis of one Degassing vessel known in which a gas purging ring with non-directional porosity is used. From the outside to the inside gas is supplied through the undirected pores, which then between the molten steel and the refractory Lining runs in order to form a base in the To prevent proboscis area.

The invention is based, known Optimize gas purging devices for degassing vessels, in particular a reduced and more uniform Wear behavior of the refractory ceramic lining is sought.

• Das Gas muß sehr feinblasig in die Schmelze eingedüst werden.
• Das Gas muß in einem nahezu lückenlosen Gasschleier umfangsseitig zugeführt werden.
• Die Gaszuführung soll so erfolgen, daß das Gas möglichst nur im unmittelbaren Wandbereich des Rüssels aufsteigt.

The invention is based on the knowledge that this goal can be achieved by "all-round rinsing" of the steel passed through the trunk (the dip tube) with an appropriate treatment gas, if the following parameters are taken into account:

• The gas must be injected into the melt with very fine bubbles.
• The gas must be supplied on the circumference in an almost complete gas curtain.
• The gas should be fed in such a way that the gas rises only in the immediate wall area of the proboscis.

The channels of the gas purging device should be in small distance to each other over the entire circumference and preferably over at least part (e.g. 10th up to 50%) of the height of the refractory lining of the proboscis extend.

What is required is an even, almost "gapless" Gas supply in fine distribution over the entire scope of the Proboscis.

Thereafter, the invention relates to its most general Embodiment a gas purging device with the features of claim 1.

The following advantages result from such a design: There will be a steady flow of molten steel into the Vacuum vessel reached. The distributed over the entire scope fine-bubble gas supply enables a particularly fine Distribution of the treatment gas with a strong at the same time increased reaction volume between treatment gas and Melting steel. The gas rises on the inner wall of the proboscis and protects the fireproof lining material of the trunk. The result is a much more even and less wear of the refractory material not only in the Proboscis itself, but also in the lower vessel of the vacuum system.

A bear formation, as it is partly in the state of the art in middle and upper part of the vacuum vessel observed has almost never occurred. The treatment time of steel with alloying elements is reduced. The amount required is reduced accordingly Alloying agents. Finally, it can be a higher and Achieve faster decarburization performance so that less Amounts of reducing media become necessary.

The constructive design of the ring-like Gas purging device can be in different ways be modified. In a first embodiment provided the gas purging device as a monolithic, to design cast or pressed annular block, in which the channels are arranged radially.

The annular block can also consist of several there are refractory, for example pressed ring segments, where the channels run in the individual segments.

Each ring segment is, depending on its size, formed with a corresponding number of channels, wherein a further embodiment provides the channels one Ring segment on the outside to a common gas distribution chamber to connect, which in turn to a Gas supply line can be connected. The Gas distribution chambers also flow-wise among themselves be connected so that only one Gas supply line is required. This will make the supplied gas flow equalized. In connection with the feature of forming channels with very small Opening width (or very small diameter) makes this possible, compared with the prior art lower gas pressure to work and so that the Gas rises immediately after entering the trunk.

The shape and size of the ring segments can vary widely can be varied. For example, it is possible annular gas purging device consisting of a total of ten ring segments build up. Each ring segment can in turn consist of several stones, whereby in all stones the Channels are formed.

Regardless of the structural design of the ring-shaped Gas purging device, the gas channels rotationally symmetrical over the circumference of the refractory Place the trunk lining. This will create a particularly even radial gas supply in the Metal melt guaranteed. Are the gas channels with different diameters (e.g. 0.5 to 1.5 mm) or cross sections (such as round, slit-like, etc.) trained, the gas pressure can be from channel to channel adjust so that the gas supplied can penetrate into the molten metal at different depths, however, as shown, according to the invention always only via one relatively short distance.

The channels can be simple holes; after a Embodiment, the channels are formed by metal pipes, that lie firmly in the refractory lining.

The distribution of the treatment medium within the Molten metal is further improved in that the Gas ducts are alternately offset in height become. The following embodiment shows one such embodiment in detail.

Normally the channels are aligned horizontally run; however, one is also inclined to the horizontal Arrangement of the channels conceivable, the channels then For example, are aligned so that the gas supply takes place against the flow direction of the molten metal.

The described formation of a gas purging device at the metal melt passed through the proboscis evenly on the circumference almost continuously (continuously) with the finest Gas bubbles are applied, resulting in metallurgical Terms of a distinct surprising advantage of the Treatment of the molten metal and at the same time one Improved durability of the refractory material.

Further features of the invention result from the Characteristics of the subclaims and the other Registration documents.

The invention is based on a Embodiment described in more detail.

Figur 1:

eine perspektivische, teilweise aufgerissene Ansicht eines RH-Entgasungsgefäßes,

Figur 2:

eine Aufsicht auf eine Gasspüleinrichtung gemäß der Erfindung,

Figur 3:

eine Frontansicht eines Steines der Gasspüleinrichtung nach Figur 2.

Here show - each in a schematic representation -

Figure 1:

2 shows a perspective, partially cut away view of an RH degassing vessel,

Figure 2:

a top view of a gas purging device according to the invention,

Figure 3:

3 shows a front view of a stone of the gas purging device according to FIG. 2.

Figure 1 shows a partial perspective view of a RH degassing vessel and especially the one here area of interest of two proboscis (inlet proboscis 10, Discharge nozzle 12).

In the cut part of the trunk 10 is a refractory Lining 14 can be seen here, from a total of seven ring-like and superimposed levels 16a ... f consists. Each level 16a ... f is made of refractory bricks 18 composed.

The stones 18 of the level 16d together form one Gas purging device according to the invention, which in FIG Supervision is shown in detail.

Figure 2 shows that forty stones 18 together the form annular plane 16d, each with four stones 18 are combined to form a ring segment S1 to S10. The Stones 18 or segments S1 to S10 are on theirs corresponding side surfaces mortared together.

As FIG. 3 shows, each stone 18 has two horizontally aligned and radial with respect to the central longitudinal axis M of the trunk 10 extending channels 20, 22 on the Height and laterally offset, their distance each is about 5 cm, both between the Channels 20, 22 of a stone, as well as between the channels neighboring stones.

The channels 20, 22 (with an inner diameter of each 1 mm) each run from the outside 18a to Inside 18i of stones 18.

Each segment S1 to S10 has one on its outer surface directly connected gas distribution chamber 24, the is connected gas-tight to the outer surface and made of metal consists. The channels 20, 22 run accordingly on the outside in the gas distribution chamber 24 Room.

Each gas distribution chamber 24 has one (not here shown) connection area over which the Gas distribution chamber 24 is supplied with the treatment medium, which then through the channels 20, 22 into the trunk interior 26 can be injected, the close-knit, even and height-offset distribution of the channels 20, 22 about the scope of the gas purging device and its radial Alignment ensure that the treatment medium, for example argon, evenly towards the im Space 26 flowing molten metal is injected radially. This creates a kind of circular gas curtain formed on the cylindrical inner wall of the Proboscis 10 rises.

Alternatively, it would also be possible to use the individual gas distribution chambers 24 (tangential) to connect with one another only gas supply line into a gas distribution chamber 24 to lead. In any case, it ensures that all Channels 20, 22 the same gas pressure is created.

It is within the scope of the invention, not just one Level 16a ... f as a gas purging device according to the invention train, but also several levels 16a ... f, the can be adjacent or spaced apart.

The arrangement of the channels 20, 22 can vary from stone to stone 18 vary.

Claims (10)

1. A gas purging device for a blowpipe (10, 12) of a degassing vessel, the blowpipe being lined with a refractory material, the gas purging device having a plurality of channels (20, 22) which run, distributed over the periphery of the blowpipe (10, 12), through the refractory lining (14) in radial direction with regard to the central longitudinal axis M of the blowpipe (10, 12), and are connectable at the outside to at least one gas supply pipe, and can be supplied with gas in such a way that said gas after entry into the blowpipe (10, 12), ascends directly adjacent to the inner wall of refractory material thereof, characterized in that the channels (20, 22) for further gas supply into the metal melt

   a) have different cross-sections or different diameters between 0,5 and 2 mm,

   b) have a distance between each other of less than 10 cm, and

   c) are offset in height.
2. The gas purging device according to claim 1 in the form of a monolithic, ring-shaped block of refractory material having channels extending therein.
3. The gas purging device according to claim 1 in the form of a ring-shaped block of a refractory material, which is formed by several refractory ring segments S1 to S10 having channels (20, 22) arranged therein.
4. The gas purging device according to claim 3, wherein each ring segment S1 to S10 consists of several bricks (18), through each of which at least one channel (20, 22) extends.
5. The gas purging device according to any of claims 1 to 4, wherein the distance of adjacent channels is between 2 and 7 cm.
6. The gas purging device according to any of claims 1 to 5, wherein the channels (20, 22) at the outside (at the end towards the gas supply) run in groups or altogether into a common gas distribution chamber (24).
7. The gas purging device according to any of claim 1 to 6, wherein the diameter of the channels is 1 mm or less.
8. The gas purging device according to any of claims 1 to 7, wherein the channels (20, 22) are arranged in rotational symmetry along the periphery of the refractory lining (14) of the blowpipe (10, 12).
9. The gas purging device according to any of claims 1 to 8, wherein the channels (20, 22) are formed by metal tubes embedded securely in the refractory lining (14).
10. The gas purging device according to any of claims 1 to 9, wherein the channels (20, 22) are inclined to the horizontal.

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