KR20040031109A - Arc furnace and method for operating this arc furnace - Google Patents

Abstract

The present invention relates to an arc furnace and a method for operating the arc furnace, which can be tilted or remain fixed for tapping of the melt or slag and are provided with eccentric tabs and / or center tabs 9; In order to improve such an arc furnace and its method of operation in the production situation as well as in the production situation by structural modification, the tab 9 is provided in the separately attached protrusion 6, and the protrusion 6 is provided in the lower container 2. One or more tapping channels 5 abutting the fastening wall 4, connecting the furnace shell 2a and the projection 6, are provided through the fastening wall 4.

Description

ARC FURNACE AND METHOD FOR OPERATING THIS ARC FURNACE

It is known to tap the melt on the basis of the various configurations of the arc furnace. Such tapping is accomplished by tilting through an open cast gutter. Tapping is also possible through casting troughs with closed siphons. In the arc furnaces of the mentioned embodiments it is known to arrange eccentric bottom tabs in the furnace vessel projections EBT (DE 82 31 869.7 U1 and DE 198 26 085 A1). Such eccentric tabs are also used in elliptical furnace vessels (OBT). In addition, a central bottom tab is used for a circular container.

Although several such structural modalities have proved effective, the bottom tabs still have room for improvement from an operational point of view.

The present invention relates to an arc furnace and a method of operating the arc furnace, which can be tilted or remain fixed for tapping of the melt or slag, and have an eccentric tab and / or a center tab.

1 is a cross-sectional view showing only the lower container of the tiltable arc furnace,

2 is a plan view corresponding to FIG. 1;

3 is a cross-sectional view of the fixed arc furnace showing only the lower container;

4 is a plan view corresponding to FIG. 3.

Explanation of reference numerals

1 Acro 2 Lower Container

2a no shell 3 hearth

4 fastening walls 5 tapping channels

6 protrusion 7 flange

8 Flange linkage 9 tab

9a tapping opening 10 lining profile

11 Zero position 12 Floor tapping opening

13 locks 14 hollow plug

15 Hollow plug housing 16 Pressure and vacuum seal cover

17 Gas Valve 18 Slider

It is an object of the present invention to improve the operational process as well as to improve the manufacturing and operating situation by structural changes.

This set object is achieved in accordance with the invention by providing tabs with separately attached protrusions, the protrusions contacting the fastening wall of the lower container and having at least one tapping channel connecting the furnace shell and the protrusions provided through the fastening wall. do. By such structural modifications, particularly round or oval containers are improved to be inexpensively manufactured. The fastening wall can be formed continuously in the protrusion zone, thereby achieving a high shape stability and improved clamping of the refractory lining. The attachment of the projections separately means high flexibility during operation, since the projections can be replaced thereby. There is no need to replace ventilation bricks in hot furnace zones. The tapping channel may well enter and exit from the protrusion. In individual cases, the protrusion cover can be omitted. Providing a tab disk or tab flap is not necessary, but is limited to specific cases. In addition, the lining material is saved.

The configuration is even more advantageous by allowing the protrusion to be connected to the fastening wall of the lower container by means of a flange connection device. Moreover, such a flange connection device can be formed as a replaceable door.

Moreover, according to another feature, it is advantageous to significantly empty the lower container such that one or more siphoned tapping channels extend through the fastening wall with approximately abutting the lining profile.

In that case, the tap is arranged by allowing the tapping opening of the tab in the projection to extend vertically at the zero position of the arc, ie the horizontal position of the arc furnace.

An alternative solution is to allow the tapping opening to be formed at an angle matched to the tapping angle of the furnace, which can be tilted.

The method of operating an arc in which the inclination is inclined in one turning direction for the tapping of the melt and in the other turning direction for the tapping of the slag, and the melt is eccentrically tapped against the lower container, is first applied from the protrusion side in the lower container. Opening the tapping channel by burnout, starting the tilting process when the melt flows out into the protrusion, then filling the protrusion sufficiently, then opening the tapping opening (from above) and zeroing the arc when the tapping amount is reached It may be done in such a way that it tilts back to or beyond the position. In this way, the operation is advantageous due to a simple workflow.

Alternatively, another step may be configured in such a way that the tapping channel is first opened by burnout from the projection side in the lower vessel and the pouring is inclined through the unclosed tapping opening when the melt flows out into the projection. As a result, closing the tapping opening is omitted.

In the configuration of the present invention, further measures can be taken in the form of cleaning the tapping channels and / or tapping openings and closing them with the refractory material after reaching the zero position.

After a long corresponding operating time, alternative measures are provided by removing the projections in the neutral state of the flange connection and replacing them with new bricked ones.

It is also preferred to introduce the necessary amounts of additives and alloys or portions thereof into the protrusions during tapping.

An alternative method of operating an arc furnace in which one is inclined in one turning direction for the tapping of the melt and the other in the turning direction for tapping the slag, and the melt is eccentrically tapped against the lower vessel is to be pressure and vacuum sealed. The tapping speed is controlled by controlling the gas pressure in the protrusion by pushing the inert gas to the shielded protrusion. In that case, the tapping opening of the tiltable furnace should be closed. By controlling the gas pressure during the tapping process, it can affect the siphon action established between the hearth and the protrusions along the length of the tapping channel and appear as negative pressure in the protrusions at the top of the bath surface.

In an arc furnace having a tapping opening which can be closed, a lower vessel being fixed, and a bottom tapping opening, another alternative embodiment of the present invention is provided with a tab attached separately and provided with a pressure and vacuum sealed protrusion. The protrusion abuts the fastening wall of the lower container, at least one tapping channel connecting the furnace shell and the protrusion is provided through the fastening wall, the lower edge of the tapping channel lies on the side of the protrusion, and the top of the tapping opening of the protrusion is It is constructed in such a way that the edge is set slightly higher. If so, the arc furnace does not need to tilt anymore. In addition, the operating process and operating behavior are changed.

The required gas space in the protrusion is provided by providing a pressure and vacuum sealed cover on the protrusion.

In addition, the tapping openings of the protrusions can be maintained in spite of the cover by allowing the hollow plug to be disposed in the hollow plug housing that can be separated or connected by a lock on the pressure and vacuum sealed cover and can be opened or closed.

Another structural configuration is given by allowing a gas supply device with a gas valve to be connected to a pressure and vacuum sealed cover.

The above-described alternative in which the arc furnace is fixed is considered as the basis of a method of operating the arc furnace, which is fixedly arranged, has a protrusion attached to the lower furnace and provided with a tapping opening, and having a center bottom tapping opening. Such a method is such that, after opening the tapping opening of the protrusion and propelling inert gas to the protrusion, the on-going tapping is stopped by a decrease in the negative pressure in the protrusion as soon as the bath surface in the lower container lies below the bottom edge of the tapping channel on the protrusion side. It is tapping while controlling the melt. This allows you to stop tapping without incurring significant costs.

Another preferred method of action is to set the gas pressure in the projection and gas pressure in the tapping channel to a pressure value such that the bath surface is at the height of the upper edge of the tapping channel extending towards the lower vessel. Thereby, the projection and tapping channel can be kept free of metal after the tapping opening of the projection is closed. In that case, the pressure in the protrusion is set so that the gas consumption is always constant and the gas on the tapping channel side toward the furnace causes only a small amount of bubbles in the metal bath. In such a mode of operation it is not necessary to open the tapping channel by burnout on the side and to close the tapping channel again.

In the above-described mode of operation, when the tapping opening of the projection is opened, the gas pressure in the projection is automatically released immediately. Thus, the tapping process can be initiated by opening the tapping opening of the protrusion according to a further method step. At that time, tapping begins to proceed through tapping channels and tapping openings of the protrusions without the need for tilting and moving. The sand charges in the tabs of the protrusions do not stick to the surface because the sand charges are not exposed to the liquid metal bath. For that reason, simply turning the slider plate away allows the tab to be opened smoothly without any problems.

Despite the pressure and vacuum sealed cover, the tapping opening of the protrusion can be closed from above. To this end, measures are taken to complete the tapping by closing the tapping opening of the open protrusion by filling sand to the slider through a hollow plug that can enter through the cover. Thus, the sand reaches the tapping opening of the protrusion in front of the slider closed through the hollow plug to fill the space therein. The tapping channel prevents scrap pieces roughly lying in the tapping opening of the protrusions from impairing the impaired function of the hollow plug.

After using the hollow plug, the hollow plug can be replaced by closing the lock and then replacing the hollow plug on the cover. In addition, a "paddle" is advantageous to prevent sand from escaping from the tapping opening of the protrusion.

In the accompanying drawings, an embodiment of the present invention is shown, which will be described below, and a number of methods for operating the arc furnace on the basis thereof will be described.

Hereinafter, the description will be made mainly with reference to FIGS. 1 and 2. Only the lower vessel 2 with the furnace shell 2a bricked towards the hearth 3 of the arc furnace 1 is shown. The acro 1 is directed in both turning directions for tapping the melt or tapping the slag. Can be tilted accordingly (FIG. 1).

The tab for lysate 9 is arranged in a separately attached protrusion 6 which abuts the fastening wall 4 of the round or oval bottom container 2 formed as an upper flange (FIG. 2). . From the hearth 3 one or more tapping channels 5 extend transversely through the fastening wall 4, which tapping through the protrusion wall completely siphoning about the lining profile 10. Guided by

The protrusion 6 is connected to the fastening wall 4 of the lower container 2 by a flange connecting device 8. The flange 7 is provided in the protrusion 6 and the lower container 2. The tapping opening 9a of the protrusion extends vertically at the zero position 11 of the arc furnace 1. Alternatively, the axis of the tab 9 may be formed at an angle adapted to the tapping angle of the furnace 1.

Now, the arc furnace 1 can be inclined in one turning direction or another turning direction for the tapping of the melt and slag, the melt is tapping eccentrically with respect to the lower container 2. In that case, first, the tapping channel 5 is opened by the burnout in the lower container 2, and when the melt flows into the protrusion 6, the pouring process is started. When the projection 6 is sufficiently filled, the tapping opening 9a of the projection is opened, and when the tapping amount is reached, the arc furnace 1 is tilted back to or above the zero position.

Another way is to first open the tapping channel 5 from the side of the protrusion 6 in the lower container 2 by burnout, and tilt it through the unclosed tab 9 once the melt has spilled into the protrusion 6. It consists of a form that initiates the pouring process.

Once the zero position 11 has been reached, the tapping channel 5 and / or tapping opening 9a of the projections are cleaned and, if necessary, closed with a refractory material.

Alternatively, the projections 6 can be separated in the neutral state of the flange connection device 8 and replaced with newly provided projections in order to obtain a correspondingly high tapping output.

Further, by introducing the necessary amount of additives and alloys or portions thereof into the protrusions 6 during tapping, the protrusions 6 can be used more advantageously.

The fixed furnace of FIGS. 3 and 4 will now be described.

According to FIG. 3, when the lock 13 is opened, the hollow plug 14 passes through a pressure and vacuum-sealed cover 16 (the gas valve 17 is closed) through the hollow plug housing 15 The state just entering is shown. When the gas valve 17 is opened, pressure is pushed against the protrusion 6. In the next step, the hollow plug 14 is moved to the parking position or the alternating position (as shown) when the tapping opening 9a of the protrusion is closed by the slider 18. Pressure is exerted on the protrusion 6. In this case, an inert gas blows bubbles into the hearth 3 at the upper edge of the tapping channel 5. In the third step, tapping is started. Open the slider 18. The existing sand filling is taken out, and the protrusion 6 is brought into a pressureless state close to atmospheric pressure. Now, the tapping of the liquid metal proceeds. A few seconds after starting tapping, the liquid metal flows down through the tapping opening 9a of the protrusion. In the fourth step, a negative pressure is formed in the protrusion according to the principle of the siphon. The hollow plug 14 is positioned in the parking or alternating position as before. In the fifth step, the hollow plug 14 is entered, the slider 18 is closed, sand is inserted, and gas is pushed into the protrusion 6. Then, the projection 6 is emptied, and the tapping channel 5 is emptied as well. Thereafter, the hollow plug 14 is pulled out to the parking position or the alternating position.

If necessary, the furnace can be completely emptied from the bottom tapping opening 12.

Claims (20)

In an arc furnace that can be tilted or remains fixed for tapping of melt or slag, and has an eccentric tab and / or a center tab, The tab 9 is provided on a separately attached protrusion 6, the protrusion 6 abuts the fastening wall 4 of the lower container 2 and connects the furnace shell 2a and the protrusion 6. The arc furnace characterized in that the above tapping channel (5) is provided through the fastening wall (4). 2. Arc furnace according to claim 1, characterized in that the projection (6) can be connected to the fastening wall (4) of the lower container (2) by a flange connection device (8). The arc furnace according to claim 1, wherein the at least one siphon type tapping channel (5) extends through the fastening wall (4) with approximately abutting the lining profile (10). The tapping opening 9a of the tab 9 in the projection 6 extends vertically in the zero position 11 of the arc furnace 1, ie in the horizontal position. An arc furnace, characterized in that. The arc furnace according to any of the preceding claims, characterized in that the tapping opening (9a) is formed at an angle adapted to the tapping angle of the furnace (1) which can be tilted. In a method of operating an arc furnace inclined in one turning direction for the tapping of the melt and in the other turning direction for the tapping of the slag, the melt is tapping eccentrically with respect to the lower container, First, in the lower container 2, the tapping channel 5 is opened by the burnout from the side of the protrusion 6, and when the melt flows out into the protrusion 6, the pouring process is started, and then the protrusion 6 is sufficiently filled. Then opening the tapping opening (9a) and tilting the arc furnace (1) back to or above the zero position (11) when the tapping amount is reached. In a method of operating an arc furnace inclined in one turning direction for the tapping of the melt and in the other turning direction for the tapping of the slag, the melt is tapping eccentrically with respect to the lower container, First, the tapping channel 5 is opened by the burnout from the projection 6 side in the lower container 2, and when the melt flows out to the projection 6, the pouring process is inclined through the unclosed tapping opening 9a to start pouring. Method of operation of the arc furnace characterized in that. 7. A method according to claim 6, characterized in that after reaching the zero position (11), the tapping channel (5) and / or tapping opening (9a) is cleaned and closed with a refractory material. Method according to one of the claims 6 to 8, characterized in that the protrusions (6) are separated into a neutral state of the flange connection device (8) and replaced with a new brick covering. 10. A method according to any one of claims 6 to 9, characterized in that the amount of additives and alloys or portions thereof required during the tapping is introduced into the projections. In a method of operating an arc furnace inclined in one turning direction for the tapping of the melt and in the other turning direction for the tapping of the slag, the melt is tapping eccentrically with respect to the lower container, A method of operating an arc furnace characterized in that the tapping speed is controlled by controlling the gas pressure in the protrusion (6) by pressure-propelling an inert gas to the pressure and vacuum-tightly shielded protrusion (6). In the arc furnace which is provided with the tapping opening 9a which can be closed, the lower container 2 is fixed, and the bottom tapping opening 12 is provided, The tab 9 is provided in a separately attached and pressure and vacuum sealed protrusion 6, the protrusion 6 abuts the fastening wall 4 of the lower container 2, the furnace shell 2a and the protrusion 6. Is provided through the fastening wall 4, connecting the lower edge of the tapping channel 5 to the side of the protrusion, and the upper edge of the tapping opening 9a of the protrusion is slightly Arc furnace, characterized in that it is set high. 13. The arc furnace according to claim 12, characterized in that a cover (16), which is pressure and vacuum sealed, is provided on the protrusion (6). 14. The hollow plug 14 according to claim 12, wherein a hollow plug 14 is provided in the hollow plug housing 15, which can be separated or connected by a lock 13 and can be opened or closed by means of a lock 13 on a pressure and vacuum sealed cover 16. Arc furnace, characterized in that it is arranged. The arc furnace according to claim 12, wherein a gas supply device with a gas valve is connected to the pressure and vacuum-sealed cover. In the method of operating an arc furnace, which is fixedly arranged, has a protrusion 6 attached to the lower furnace 2a and provided with a tapping opening 9a, and which has a center bottom tapping opening 12. After opening the tapping opening 9a of the projection and pushing inert gas to the projection 6, proceeding as soon as the bath surface in the lower container 2 lies below the lower edge of the tapping channel 5 on the side of the projection 6. A method of operating an arc, characterized in that the tapping is carried out while controlling the melt such that the tapping under pressure is interrupted by a decrease in the negative pressure in the projection (6). The gas pressure in the projection 6 and the gas pressure in the tapping channel 5 are set to a pressure value such that the bath surface is at the height of the upper edge of the tapping channel 5 extending towards the lower vessel 2. Method of operation of the arc furnace characterized in that. 18. A method according to claim 16 or 17, characterized in that the tapping process is initiated by opening the tapping opening (9a) of the projection. 19. The tapping opening of the protrusion according to any one of claims 16 to 18, which is opened by filling sand to the slider 18 via a hollow plug 14, which can enter through the cover 16. Method of operation of the arc furnace characterized in that the tapping is terminated by closing 9a). 20. A method according to any one of claims 16 to 19, characterized in that the hollow plug (14) is replaced on the cover (16) after the lock (13) is closed.