EP0959316A1 - Vessel for liquid metal with a taphole closing device - Google Patents

Abstract

The melting vessel is especially for ferrous metals. It has a tapping hole (3) and a tapping hole closure unit (5). It is characterized by the fact that the closure unit incorporates a cooled tapping mandrel (8) which closes the tapping hole.

Description

The invention relates to a melting vessel with a tap opening and a device for closing the tap opening.

There are a variety of processes in the prior art which are melted and / or treated in a vessel becomes. This is usually used for removal from the vessel stabbed through a tap hole. This is common especially in iron and / or steel production.

Different systems for parting off electric steel furnaces are described in electrical steel production, 4th ed., published by Karl-Heinz Heinen on behalf of the Association of German Ironworkers.

The conventional tapping channel and siphon tapping described there are disadvantageous because they are tiltable and therefore very complex furnace construction required, so when parting off prevents the slag from running along as far as possible becomes. Conveying furnace slag considerably complicates the subsequent metallurgical treatment of a molten steel.

The cited prior art also describes an im Vertical tapping system arranged in the area of the furnace floor, designed as a so-called eccentric floor cut can be. Here too, in order to avoid the tracking of Furnace slag and for closing the tap hole with refractory granules after tapping Melting vessel can be tilted.

The central floor tapping does not require any tilting movement for tapping, but must be completely emptied before filling, so that the furnace slag cannot be retained.

DE-A-195 00 407 describes a device for closing the tap opening of a shaft furnace which is manufactured according to the "process the lost rod ". To close the Tap hole after tapping is first a Stuffing compound filled into the tap hole and then through an explicitly described as violent introduction of a Tapping rod by means of a complex hydraulic device condensed.

The invention has for its object a melting vessel to create the kind mentioned in the introduction of the racking and reclosing the racking opening after tapping is possible with little effort is.

The invention solves this problem in that the device to close the tap opening with a cooling device provided tapping mandrel, in its closed position closes the tap hole.

First of all, let us consider some of the terms used in the context of the invention explained.

A melting vessel is any vessel that holds any Melt for treatment and / or storage purposes serves. The invention particularly relates to metallurgical Melting vessels, however, is not necessarily on it limited.

The tap opening serves to remove the melt and penetrates it usually a wall or the bottom of the melting pot.

According to the invention for closing the device Tapping opening a tapping pin. It is about an elongated mandrel or a rod which in the Tap hole is insertable. The tapping pin penetrates in its closed position the longitudinal extent of the tap opening completely or partially. He can in this closed position its tip also protrude into the melting vessel. To the The mandrel does not necessarily have to close the tap opening fill out the entire cross-section of the tap hole, so fit positively on the wall of the tap hole. A certain undersize of the tapping mandrel relative to the free cross-section of the tap hole is harmless as long as a corresponding gap between the outer circumference of the mandrel and inner circumference of the tap opening due to solidifying melt is closed.

The tapping mandrel is according to the invention with cooling devices Mistake. These cool the outer surface facing the melt of the mandrel to a temperature below the solidification temperature the melt, so that immediately around the mandrel around it forms an area of solidified melt which is to be closed contributes to the tap opening. If the tip of the thorn something protrudes into the melting vessel, forms over the furnace-side entrance of the tap opening a closure hood from solidified melt.

The invention enables the tap opening to be closed simply by inserting the cooled tapping mandrel. Of the area of solidified melt forming around the mandrel contributes to the closure. It is different from the state of the Technology, no additional closure of the tap opening with a filling or stuffing compound is required. An expensive one and filling the opening, which is stressful for the personnel omitted. Tilting the melting vessel to perform the Backfilling is therefore not necessary on an elaborate The tilt mechanism can be dispensed with.

To initiate the tapping process, the mandrel is removed from the tapping opening pulled out. Because the heat dissipation through the cooled The overheated melt melts and the mandrel is no longer required the hood of solidified melt in the vessel, and the racking begins.

The tapping mandrel itself is subject to only one low thermal wear, as it is constantly cooled during operation becomes.

Water and gas are preferred as the cooling medium for the tapping mandrel or a water / gas mixture is used. The use of others Cooling media such as liquid sodium are also conceivable.

For safety reasons, there should be contact between the melt (especially a metallurgical melt) and cooling water be avoided. A contact of molten metal with cooling water can cause explosive reactions, especially then when water is trapped by the molten metal, since the expansion of the water vapor then takes place in the melt tears apart explosively. Also a chemical one Decomposition of the water and subsequent detonating gas reactions cannot be ruled out.

In a particularly preferred embodiment of the invention the tapping mandrel therefore has a cavity, at least one Device for cooling by spraying a cooling medium in this cavity, and at least one catching device for collecting of molten metal breaking into the cavity on.

In the context of the invention, the term “spraying” any distribution of the cooling medium in the cavity in such a way that at least part of the inner wall of the cavity of being chilled to understand. Finely divided is preferred Spray using one or more nozzles. As a cooling medium water or a water / air mixture is preferably used. The use of other cooling media is also possible. A particularly high cooling effect can be achieved through the Achieve the use of liquid sodium as a coolant.

Under a trap for breaking through molten metal is to be understood any institution that the further Penetration of molten metal broken into the cavity towards the outer wall of the metallurgical vessel prevented or at least delayed. Provided as a coolant Sodium is used, the safety gear must be designed be that they reflux the heated sodium not or only insignificantly disabled.

With a tapping mandrel designed in this way, the result is immediate Neighborhood between molten metal and spray cooled Cavity inside the tapping pin practically no Security risk. Should it be exceptional at unfavorable Operating conditions (e.g. failure of cooling or overheating through oxygen lances) to such a large extent Melting off the tapping mandrel comes that melt in the Breaks through, this is through the safety gear stopped. Leakage of the melting vessel through the blown The tapping pin is avoided.

The invention has recognized that due to the spray cooling used a relatively small amount of water Risk of explosion from contact of molten metal with the Spray mist surprisingly does not exist. The safety gear are designed so that the return of Only insignificantly hinder the cooling medium. Thus, with one Breakthrough of melt in the corresponding cavity area Any coolant that may still be present can be drained off or removed quickly become. This will prevent that from metal melt stopped in the traps includes a lot that creates an explosion hazard.

When using water or a water / gas mixture the operating conditions are advantageously as the cooling medium chosen so that the water when hitting the Cooling inner wall of the cavity largely or completely evaporates. This has two advantages. For one uses not only the heat capacity of the water for cooling, but also the much greater heat of vaporization for the Phase transition water-steam and thus maintains even at proportionate low cooling water flows a high cooling capacity. Provided that there is one in exceptional operating conditions Breakthrough of molten metal comes into the cavity shortly before this breakthrough the temperature in the cavity so far increase that practically all the water evaporates and the Metal melt after the breakthrough not even with sprayed Water, but only in contact with water vapor is coming. This means a further reduction in the risk of explosion. Thus, the setting of the operating conditions in such a way that it sprayed during normal operation Water or most of it when hitting the Cavity wall evaporates, for a further increase in security.

The heated water flowing out of the cavity and / or the Water vapor is conveniently from a vacuum source such as a vacuum pump. It is possible that Select the suction power of the pump higher than for the discharge of the spray water required. Through an additional inlet can then let in additional air if necessary and thus the Removal of the cooling medium can be promoted. So you can make sure that there is no water accumulation at the safety gear forms.

The catching device is expediently used as a device for Cross-sectional narrowing of the cavity along the major axis of the Tap mandrel trained. The main axis of the mandrel is its longitudinal axis pointing through the vessel wall. A Cross-sectional narrowing of the cavity along this major axis means that the cavity cross-section is perpendicular in the plane is reduced to this main axis. Such a narrowing of the cross-section stops or brakes the flow of the in Comparison to the cooling medium of higher-viscosity molten metal. The Cross-sectional constriction is expediently designed such that that the free cross-section into a plurality of small cross-sectional areas is divided. E.g. can the safety gear Have slotted or perforated sheets. Conveniently there are openings for the cooling medium to be removed, in the case of a perforated sheet, these are the ones arranged therein Holes, for example in the form of slots. If subsequently by Perforated sheets are mentioned, so any sheet is included openings suitable for the passage of cooling medium, such as Understand bores, slots, etc.

In a particularly advantageous embodiment of the invention is the safety gear as a so-called slit body educated. It is essentially one massive body that occupies a large proportion of the interior space of the tapping mandrel. It preferably faces radially outer area its entire length or at least essential Parts of its length through openings that are preferably designed as slots. The transverse extension these slots can run in the radial direction. The Slots are formed so that the cooling medium through them from the tip of the tapping mandrel facing the furnace interior can flow back to the end facing away from the furnace. The longitudinal extent in the slit body must be so large that the slots on the end facing away from the inside of the furnace to return areas or connect connections for cooling medium and so allow the cooling medium to flow out of the slit body.

The slot body does not hinder the backflow of the in the Cavity introduced cooling medium, but may stop breaking metal melt mechanically the narrowing of the cross-sectional area and secondly thermal by its considerable due to its large mass Heat capacity. The slit body is covered by the enamel heats and cools the front of the enamel mass far from the fact that it either solidifies or at least so becomes viscous that they no longer penetrate through the slits can. It is advantageous if the safety gear (e.g. the slit body) consist of a material that one melting point above the temperature of the molten metal having. For a metallurgical vessel for a molten steel the safety gear can be made of stainless steel, for example or copper. Copper has a high thermal conductivity rapid heat dissipation.

It is expedient in the interior of the metallurgical At least the end region of the cavity facing the vessel a nozzle for spraying cooling medium is arranged. To this This thermally highly stressed cavity end region becomes particularly effective chilled. The coolant supply to the The nozzle can be positioned essentially in the direction of the Main axis of the slit body extending tube. It is advantageously in one piece in the slot body molded. The wall of the cavity expediently consists made of a highly thermally conductive material, for example copper or a copper alloy.

The outside surface of the tapping mandrel can be hard chrome-plated. E.g. can the cavity of a copper cylinder with dome-shaped or be conical. The conclusion faces the interior of the melting vessel. This training of the end facing the interior of the vessel facilitates Formation of a melt hood closing the tap opening.

According to the tap opening at the lowest point of the Vessel must be arranged (central bottom tapping). This arrangement facilitates parting off the furnace without following Furnace slag.

In a particularly advantageous embodiment of the invention the tap opening also has a slide closure on how it is known in the prior art and, for example, in the above-mentioned literature reference "electrical steel production" is described. In those known in the prior art However, slide closures are an additional backfill the tap opening with refractory granules required, since the melt solidifies in the tap opening and becomes an independent one Opening is no longer possible.

The combination of a slide closure according to the invention and the cooled tapping mandrel works as follows:

After a tap has been taken, the tap hole is opened first only closed by means of the slide lock. Subsequently with the melting process of the next melt began. The slide is kept closed until until the melting material (the approx. 10% furnace residue or fresh Melt) has solidified over the slide plate so far that it does not come out when the slide is opened.

The slide lock is now opened and the tapping pin is in the tap hole by the partially solidified Introduced melt through. After pushing through this Melt layer, due to the conical formation of the Dorns is tight against the wall, an escape of non-solidified melt safely prevented even if it in the further course of the melting process to high temperatures comes in the melt (overheating of the melt).

The intensive cooling of the tapping mandrel leads to the formation of a solidified melt hood over the tap hole.

After the melting process, the mandrel comes out of the tap hole drawn. The hot melt melts the solidified one Hood that has formed over the cooled mandrel and the tapping process begins. Should the thermal Energy of the melt is not sufficient to melt the hood, can the tap opening from the outside, for example of an oxygen burner tube.

During the tapping process, the slide closure can serve short-term interruption of the racking if, for example the contents of the melting pot are distributed over several pans should.

An electromagnetic slag early detection system can be found in the tapping area (for example in the form of a coil), a slag run out of the tap opening in time recognizes. The tap opening can then by means of the sliding closure getting closed.

Fig. 1

schematisch einen Längsschnitt durch den Bodenbereich eines erfindungsgemäßen Schmelzegefäßes;

Fig. 2

einen Längsschnitt durch den Abstichdorn.

Fig. 3

einen Querschnitt durch den Abstichdorn.

The melting vessel according to the invention can be a metallurgical vessel, in particular an electric arc furnace. However, it can also be a blast furnace, cupola furnace or the like. An embodiment of the invention is described below with reference to the drawing. In it show:

Fig. 1

schematically shows a longitudinal section through the bottom region of a melt vessel according to the invention;

Fig. 2

a longitudinal section through the tapping mandrel.

Fig. 3

a cross section through the tapping mandrel.

The electric arc furnace designated as a whole has 1 a stove 2, in the bottom of the stove at the lowest point a tap opening 3 is arranged.

The vertical tapping system has tapping blocks 4. It are known in the prior art and the expert common components. There will be several tapping blocks at a time arranged one above the other in the longitudinal direction of the tap opening, to enforce their entire length. You are with one chemically setting mass or stamped in the hot state been poured in.

The tapping blocks can, for example, be made of carbon-bonded and graphite-containing magnesia or enamel magnesia varieties consist.

At the exit of the tap opening there is a total of 5 Slider lock arranged. He has two relative mutually displaceable slide plates 6, 7 on the release the tap hole in the condition shown and these can be closed by moving them relative to each other. The technical design of such a slide closure is familiar to the expert and does not require any here detailed explanation.

According to the invention, a cooled tapping mandrel 8 is provided, by means of a lifting or moving device 9 into the tap opening 3 can be retracted or extended.

The tapping mandrel 8 fills the free cross section of the tapping opening 3 partially off. Remaining marginal columns will be sealed by solidified melt. Above the conical (or dome-shaped) tip 10 of the mandrel forms due to a hood made of solidified melt for cooling the mandrel, which also contributes to the closure of the tap opening 3.

1 shows the melting vessel according to the invention in the state in which the tapping mandrel 8 closes the tap opening 3. When the melting process is complete, it is initiated the tapping of the tapping mandrel 8 by means of the displacement device 9 moved out of tap opening 3. The Melt melts the hood over the tap opening 3 and the racking begins.

Facilities in the area not shown in the drawing the tap opening detect any slag run in the area of the tap opening 3. As soon as it comes at the end of the rack to slag idling, give this a signal from electromagnetic detection devices, the a process of the slide plates 6,7 in their closed position triggers.

The tapping process is now complete and the melting furnace 1 can be filled again with melting material and the melting process be started. The residual melt in the tap opening solidifies over the slide plates 6, 7. As soon as this melt is solidified to such an extent that it releases further melt can prevent at least briefly (is in the oven only a little melt in the early stage of the melting process, usually only about 10% furnace residue) Slide lock 5 opened and the cooled tapping pin 8 moved into the tap opening 3 by means of the displacement device 9. It is thereby caused by the partially solidified melt pressed in the tap opening 3. This partially solidified melt attaches itself firmly to the outer wall of the Dorns 8 from. Over the tip 10 arises in the further course the melting process due to the intensive cooling of the mandrel 8 again a hood made of solidified melt.

2 and 3 show the structure of the tapping mandrel. He points an outer wall 11 which extends to the tip 10 of the tapping mandrel slightly tapered cavity. The wall 11 is made of copper or a copper alloy, the outside is hard chrome-plated.

In the cavity enclosed by the wall 11 is a Slotted body 12 is used essentially positively. He consists preferably of copper or a copper alloy. In its radial outer area facing the wall 11 he a plurality of longitudinal slots open radially outwards 13 on. Runs centrally in the longitudinal direction of the slit body 12 a coolant line 14 via cooling supply lines 15, 16 and a mixing chamber 17 is fed with coolant.

When the tapping mandrel is operated, the flow line 15 Air or another gas and in the supply line 16 water fed. Mixing takes place in the area of the mixer 17 to a water / gas mixture, the water content in the mixture is preferably in the form of fine droplets. This cooling mixture is through line 14 towards the top 10 of the tapping mandrel and is conveyed through a nozzle 18th sprayed onto the inside of the wall 11 in the area of the tip 10. The coolant absorbs heat there (possibly with evaporation or partial evaporation of the water content) and is through the 10 axially open slots in the area of the tip 13 of the slit body 12 in the direction of the return line 18 promoted. When passing through the slots 13 it cools the wall 11 in the entire thermally stressed length section the tapping pin. The wall 11 is cooled partly directly by the flowing past Coolant, since the slots 13 are radially open, partially it is done indirectly by first putting the heat into the well thermally conductive material of the slit body 12 derived and is then absorbed by the coolant.

The slit body 12 is also a catching device against Breaking through melt in exceptionally unfavorable operating conditions (e.g. failure of cooling or overheating the tapping mandrel by machining with oxygen lances). Provided under such special circumstances the wall 11 of the mandrel 8 should burn out, in the of the Wall 11 enclosed cavity breaking melt immediately stopped by the slit body. Even in the event of a total failure the cooling causes the high heat capacity of the Slit body such a strong cooling of the breakthrough Melt front that this solidifies and so the leakage of the Oven is prevented through the tapping mandrel.

Claims (10)

Melting vessel with a tap opening (3) and a device to close the tap hole (5,8), thereby characterized in that the locking device the tap opening is provided with cooling devices Has tapping mandrel (8) in its closed position closes the tap hole (3). Melting vessel according to claim 1, characterized in that as a cooling medium for the tapping mandrel (8) water, gas or a water / gas mixture is used. Melting vessel according to claim 1 or 2, characterized in that the tapping mandrel (8) has a cavity, at least a device for cooling by spraying a cooling medium in this cavity, and at least one catching device for catching breakthroughs in the cavity Has molten metal. Melting vessel according to claim 3, characterized in that the wall (11) of the cavity from a good heat conductor Material exists. Melting vessel according to claim 4, characterized in that this material is copper or a copper alloy. Melting vessel according to one of claims 1 to 5, characterized characterized in that the tapping mandrel (8) is conical Has peak. Melting vessel according to one of claims 1 to 6, characterized characterized in that the tap opening (3) is deepest Point of the vessel (1) is arranged. Melting vessel according to one of claims 1 to 7, characterized characterized in that the tap opening (3) additionally a Slider lock (5). Melting vessel according to one of claims 1 to 8, characterized characterized that it is a metallurgical vessel. Melting vessel according to claim 9, characterized in that it is an electric arc furnace.

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