DE8815343U1 - Outlet and flow control device for metallurgical vessels - Google Patents

Description

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Outlet and flow control device for metallurgical vessels

The innovation relates to an outlet and flow control device for vessels containing metallurgical melts, with a pouring opening located on the bottom of the vessel and a plug that interacts with the pouring opening, the plug in its closed position having an at least approximately cylindrical pin that projects into the bore of the pouring opening and contains at least one radial throttle opening on its circumference that merges into a longitudinal bore of the pin that is open at the bottom, and a first seal that can be closed by lowering the plug is present between the plug and the pouring pipe above the throttle opening.

Numerous devices are already known for the outlet and flow control of metallic melts from a vessel.

A well-known system for pouring crude steel or similar uses a stopper device in which the outlet opening in the bottom of the vessel can be closed by a stopper inside the vessel that is attached to the lower end of a rod. The stopper can be raised for pouring and lowered again to close the spout using a lever rod that can be operated from the outside. The disadvantages, however, are the poor flow control and the unsatisfactory safety of the stopper, for example when deposits form on the stopper.

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It has also been proposed to use rotary valves in which an off-center inlet channel can be brought into communication with an outlet opening by means of a rotary connection. This requires high machining and grinding accuracy of the spherical separation point between rotating and stationary components, which is difficult to produce. In addition, the melt in the pouring opening tends to freeze. '

Also known are slide valves which are attached to the bottom of the vessel containing the melt. In such slide valves, the closure bodies which slide against one another under pre-stress are subject to considerable wear and tear, as the movement of the adjustable part must take place under the influence of the high temperature of the molten metal. Another disadvantage is the high purchase and maintenance costs. In order to ensure adequate sealing reliability, a high degree of machining accuracy is required for the slide plates, which are made of refractory material.

When casting metallurgical melts, there is also the problem of preventing slag and non-metallic inclusions from running along with the melt. This well-known difficulty of inclusion- and

Attempts have been made to solve the problem of slag-free casting in various ways. For example, it is known to use partition-like displacement bodies in distribution vessels (tundish) in order to promote the separation of non-metallic inclusions in the melt. However, it appears that in the outflow area the suction cannot prevent the entrainment of non-metallic inclusions and sludge particles. Apart from that, such dams and weirs, which have to be re-built after each casting process, are very expensive and time-consuming.

It has also been proposed to keep the slag away from the spout by blowing in inert gas . This requires a relatively high technical effort and questionable

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It is also known to arrange an electromagnetic sensor concentrically to the discharge channel, with which different measured values between molten ^metal and slag can be evaluated, so that the casting process can be interrupted if slag is detected. However, installing such sensors in wearing parts of the discharge channel is complex. In addition, some slag must first run through the discharge channel before it can be detected.

In addition, there is a further requirement that the molten metal f should not come into contact with the air if possible.

Another problem is that in distribution vessels with one inlet but several outlets, the melt temperature is different after the different outlets, which is undesirable.

Even with only one pouring spout, individual melt sections can flow directly from the pouring spout to the pouring spout and therefore have a higher temperature than parts that circulate in dead zones for a long time.

The separation of non-metallic inclusions can also cause difficulties if the residence time in the metallurgical vessel is too short or if there is strong turbulence in the melt, since these inclusions require a certain amount of time to rise to the surface of the melt.

The task to be solved by the innovation is to create an outlet and flow control device that has a high degree of closing reliability and a simple, inexpensive to manufacture structure, allows constant, precise control of the flow of liquid metal and largely avoids the formation of turbulence during pouring.

The device according to the innovation with which this task is solved is characterized in that the plug is located at the lower

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end of a height-adjustable rod which projects from above into the interior of the vessel, and the pin contains a ring part which is closed off from the jacket between its throttle opening and the sealing surface above it, which together with the adjacent part of the bore forms a second seal.

Such an outlet and flow control device according to the innovation is comparatively easy to manufacture, has a high degree of closing security thanks to the double seal and does not require a high level of machining precision. In addition, the good control characteristics facilitate pouring and precise dosing of the flow rate per unit of time during the pouring process. In addition, there is little vortex formation.

By influencing and calming the flow in metallurgical vessels, e.g. by means of the bell-shaped or mushroom-shaped head, slag is prevented from entraining, reoxidation of the melt is avoided and the precipitation of non-metallic inclusions is promoted by calming the flow.

The forced, largely horizontal flow direction in the area of the metallurgical vessel near the pouring outlet results in a calm flow without the formation of turbulence and thus without premature slag. Since the horizontal pouring opening can be rotated during the pouring process, the flow conditions of the respective vessel shape, the different bath height, the melt temperature and other parameters can be adapted from case to case or continuously. As a result of the calm pouring flow through the pouring distributor, no rebound waves of the melt from the bottom are created, which prevents the floating slag layer from winding up, which prevents reoxidation. The calm flow also facilitates and accelerates the rise of non-metallic inclusions to the surface of the melt.

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The drawing shows examples of the innovation. Show it!

Fig. 1 a section through the device including the melting vessel

Fig. 2 a partial section through the stopper in its closed position protruding into the pouring opening

Fig. 3 a section through the plug in its open position

Fig. 4 a cross-section through a variant in the direction of arrows IV-IV in Fig. 5

Fig. 5 a longitudinal section through the variant according to Fig. 4 with a large number of throttle openings

Fig. 6 shows a cross section through a further design variant with throttle openings offset from one another to generate a swirl for the outflowing melt

Fig. 7 a longitudinal section through a vessel designed as an intermediate container, with pouring distributor and several plugs

Fig. 8 a top view of the intermediate container according to Fig. showing different rotational positions of the pouring openings of the plugs in section

Fig. 9 a cross-section through the intermediate container according to Fig. 7 with a strong cross-sectional taper towards the bottom.

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According to Fig. JL, in the bottom 2 of a vessel 1 for receiving a metal melt there is an outlet opening with an outlet pipe 3 open at the bottom. A plug 6 made of refractory material extends into the bore 7 of this outlet pipe 3, with which the flow of the melt can be regulated, closed or opened.

A stopper rod 5 extends into the stopper shaft 10, with which the stopper 6 can be moved in the vertical direction and rotated about its axis. The drive is carried out by a drive device located outside the vessel 1. 17. The vertical drive can be a mechanical, motor-driven spindle 8 or a hydraulic or

(J pneumatic lifting cylinder. A horizontal arm 23 is connected to the vertical guide member 9 above the vessel rim. The connection of the arm 23 to the upper end of the stopper rod 5 and to the bell-shaped stopper head 24 at the bottom is made by a coupling ball 11. The stopper rod 5 held in the stopper neck 10 has radial play. The rotary drive device 17 provided for rotating the stopper 6 about its vertical axis is connected to a drive motor (not shown in detail). This motor can be a servo or stepping motor with which different rotational positions of the stopper 6 can be programmed and reproduced. The change in the rotational position of the stopper 6 could also be made by pneumatic or hydraulic

^J rotary drives are used.

The plug 6 contains a cylindrical pin 13 which engages in a bore 7 of the outlet channel 4. This pin 13 is provided with a horizontal radial throttle opening 14 which opens into an axial bore part 12 which is open at the bottom and merges into the pouring channel 4. Since the pin 13 is only open radially on one side, the flowing molten metal is forced into a predetermined flow direction which is indicated in Fig. 1 by the line S. In the area in front of the pouring opening, together with the bell-shaped plug which is larger in diameter than the pin 13,

head 24, a flow as horizontal as possible is aimed for in order to prevent the formation of swirls in the melt and thus the suction of slag from above. By rotating the plug 6 around its vertical axis, the flow direction can be influenced step by step or continuously during the casting process. By lowering the plug 6, the flow cross-section of the throttle opening is reduced or closed completely.

The stopper rod 23 can be fixed to the upper coupling ball 11 of the stopper rod 5 automatically using a clamping device. This means that the stopper rod 5, which can move with play, and the stopper 6 located at its lower end do not have to be precisely aligned before assembly. A stopper neck 10 surrounding the stopper rod 5 serves as protection against the melt. Since the control forces are directed directly via the stopper rod 23 into the head of the stopper 6 , the stopper 6 is protected from bending forces caused by alignment errors. The otherwise usual alignment work for the stopper 6 is no longer necessary and the stopper can also be inserted automatically in hot metallurgical vessels, which reduces vessel circulation times and thus saves maintenance costs.

The design of a variant of the plug 6 in the closed and open position is described in more detail below with reference to Fig. 2 and 3. The plug 6 contains a cylindrical or slightly conical pin protruding into the bore 7 of the pouring pipe 3.

13. In this pin 13 there are - in contrast to the embodiment according to Fig. 1 - several radial throttle openings

14. These are evenly distributed around the circumference of the pin. The upper and lower areas of these throttle openings 14 are each wedge-shaped, while the middle area of these throttle openings 14 contains parallel vertical side walls IB. The longitudinal axes of the throttle openings 14 extend in the vertical direction, i.e. in the direction of the plug movement. This allows a

achieve more advantageous control characteristics. The throttle openings 14 open into the central longitudinal bore part 15 of the pin 13, which is open at the bottom. Above the throttle openings 14, the pin 13 merges into a frustoconical widening 16, which forms a frustoconical shut-off surface. The central angle of this shut-off surface forms an angle of 75° to 105°, preferably 90°. Together with a frustoconical countersink 18 at the upper edge of the bore 7 with the same angle, this results in an annular first seal 20. Between the uppermost edges of the throttle openings 14 and the frustoconical shut-off surface 16, there is a closed, cylindrical ring part 19 with the width V on the pin 13 (Fig. 3). When the plug 6 is closed, i.e. lowered, this ring part 19 together with the adjacent cylindrical bore 7 of the same diameter forms a second seal 21. The lowest part of the pin 13 is also designed as a ring part 22 closed on the casing, so that the pin 13 remains guided in the bore 7, even when the throttle openings 14 are fully open. '

Since in the closed position of the stopper 6 according to Fig.2 the throttle openings 14 are not in contact with the melt, there is no danger of the melt freezing in this area. Above the frustoconical widening 16 the stopper head 24 is bell-shaped. This avoids or at least largely reduces an outflow vortex inside the vessel 1, so that the entrainment of slag pockets is reduced. The approximately horizontal lower edge 26 of the widened stopper head 24 has a relatively large distance from the horizontal surface 28 of the pouring pipe 3 when the stopper 6 is closed, so that a relatively wide annular space 30 for the melt is formed in front of the first seal 20. This relatively large mass of melt surrounding the bore 7 reduces its cooling and counteracts blockage. The design of the plug head 24 also forces an approximately ^horizontal flow of the incoming melt, as indicated by arrows A in Fig.3. This prevents a vertical

Vortex formation in the melt even when the melt is low in the vessel, so that slag is not drawn into the pouring spout prematurely. In addition, this annular space 39 can be flushed with argon or similar, which can be supplied via thin supply lines 33 in the stopper 6. This supply line 33 can also be used to generate a control signal. As soon as the outlet end emerges from the melt, a pressure drop occurs in the gas in the supply line. This allows the pouring process to be interrupted before slag is carried along.

Since there are two seals which act one after the other, there is increased security against melt breakouts, even if the surface 16 or the countersink 18 of the first seal 20 should be damaged by wear.

The second seal (21) can also be kept free from penetrating melt by blowing gas through holes (34).

Fig. 4 and 5 show a variant in which the throttle openings in the plug 6 are formed from a large number of relatively small radial holes 14* on the circumference, which are arranged in axial rows one above the other. This causes the melt to be filtered. When the upper holes 14' or rows of holes become clogged, the plug 6 is raised further so that new, still open holes are released for flow and filtering.

In the variant according to Fig. 6, two throttle openings 14" are arranged on opposite sides of the pin 13 and are offset from one another with respect to the central axis so that they run approximately tangentially to the longitudinal outlet opening 15. This creates a swirl in the outflowing melt according to the arrows shown, which prevents deposits on the walls of the spout since the lighter inclusions remain in the center of the swirl.

In Fig. 7, 8 and 9 a variant is shown in which the vessel 1 is designed as an intermediate container with a pouring distributor 30 and several independently rotatable pouring plugs 6. With such ^distribution vessels or intermediate containers with several pouring openings there is a problem in that the melt temperature is different due to different lengths of flow paths, which is undesirable. By immersing the pouring distributor 30 in the melt and the directed and rotatable _{predominantly} horizontal pouring opening 32 below the bath level, an approximately horizontal exit of the melt and a calm flow of about in the sense of the flow paths T in Figs. 7, 8 and 9. The KJ flow pattern depends on the inflow angle P of the inlet distributor 30 and on the outlet angles dC of the plugs 6. The flow vectors of the inlet and outlets generate a torque in the melt, whereby the individual melt elements sink in a spiral shape from the hot layer near the surface to the colder layer near the bottom. The spiral flow pattern aims to achieve a flow path that is as equal as possible for all throttle openings 14 in order to avoid temperature differences. The flow paths T shown schematically in Figs. 7, 8 and 9 will not be strictly adhered to in practice, but the mixing of the melt with partial flows results in a good temperature distribution and the avoidance of dead zones. Only one half of such an intermediate container is shown in Figs. 7 and 8.

By selecting the appropriate angles oC and β, the residence time of the melt in the vessel 1 can be influenced. »Due to the calming flow, non-metallic inclusions have the opportunity to rise quickly to the surface into the slag layer floating on it due to their own buoyancy, so that they are not carried into the outlet channel by turbulence. » This also applies to slag. Due to the forced, essentially horizontal flow in the pouring area of the metallurgical vessel 1,

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Vortexes and thus premature slag flow are avoided. This improves the quality of the end product, reduces waste and increases production.

In Fig. 9 the cross-section through the intermediate container is shown, from which it can be seen that the walls are strongly inclined, which forces a preferred flow path,

The individual plugs 6 according to the rigs 7-9 correspond to those in Fig. 6 and can thus be raised, lowered and rotated, as explained in connection with Fig. 1. The control can be carried out individually or jointly by a predetermined program, depending on casting parameters such as temperature, throughput, analysis. Data processing systems can also be used for this. The pouring distributor 30 can also be included in such a program control, ie the angle β and/or its height can be changed. The throttle cross sections of the plugs 6 can also be individually regulated by raising or lowering.

Claims (12)

Protection claims 1. Outlet and flow control device for vessels holding metallurgical melts, with a pouring opening located on the bottom of the vessel and a plug that interacts with the pouring opening, the plug (6) in its closed position having an at least approximately cylindrical pin (13) that projects into the bore (7) of the pouring opening and contains at least one radial throttle opening (14) on its circumference that merges into a longitudinal bore (15) of the pin (13) that is open at the bottom, a first seal (16f 18) that can be closed by lowering the plug (6) is present between the plug (6) and the pouring pipe (3) above the throttle opening (14), characterized in that the plug is located at the lower end of a height-adjustable rod that projects into the interior of the vessel from above and the pin (13) is between its Throttle opening (14) and the sealing surface (16) located above it contains a ring part (19) closed on the jacket, which together with the adjacent part of the bore (7) forms a second seal (21). 2= Device according to claim 1, characterized in that immediately above the ring part (19) the pin (13) merges into a truncated cone-shaped shut-off surface (16), the upper edge of the bore (7) has a countersink (18) in the pouring pipe (3), which together with the shut-off surface (16) forms the first seal (20). 3. Device according to claim 1 or 2, characterized in. duos the pin (13) contains only a single, essentially horizontal, radially arranged throttle opening (14). 4. Device according to claim 1 or 2, characterized in that the pin (13) has several, substantially horizontal, . contains radial throttle openings (14) distributed around the circumference. 5. Device according to claim 1 or 2, characterized in that the radial throttle opening or openings (14) is or are wedge-shaped at least at its upper end and an opening region adjoining these has parallel side surfaces (18). 6. Device according to one of claims 1-5, characterized in that the plug (6) above the shut-off surface (16) has a larger diameter, approximately bell-shaped or mushroom-shaped plug head (24). 7. Device according to claim 1, characterized in that the pin (13) has several rings of holes arranged one above the other along its circumference, which are released with increasing upward movement of the plug (6) (Fig. 5). B. Device according to claims 1, 2 or 6, characterized in that one or more throttle openings (14) opening tangentially into the longitudinal opening (15) are present (Fig. 6). 9. Device according to one of claims 1-8, characterized in that in the upper part of the spout (3) there are holes (34) for blowing in gas to seal the gap (21). 10. Device according to claim 3, characterized in that adjustment means (17) for rotating the plug (6) are present. 11. Device according to claim 10, characterized in that the vessel (1) is an intermediate container into which a casting distributor (30) with an approximately horizontal pouring opening (32) and that the pouring distributor (30) is provided with a · · ■ &bull; ft»*· &bull; » &bgr; Drive device (25) for height adjustment and/or a drive device (26) for rotation about its longitudinal axis. 12. Device according to one of claims 1-11, characterized in that in the plug (6) above the pin (13) at least one bore (33) for blowing in gas or powder ^opens .