EP2801627A1 - Vacuum treatment vessel for the treatment of molten metal, in particular for a RH installation - Google Patents

Abstract

The invention relates to a vacuum treatment vessel for treating a molten metal, in particular for an RH plant, comprising a base vessel having a treatment space and at least two immersion tubes arranged on the base vessel and connected to the treatment space, wherein the base vessel is designed in two or more parts, wherein at least two basic vessel parts are formed, which are connected relative to each other movable and gas-tight, and wherein at least the base vessel part comprising the dip tubes is movable, and further wherein at least one lifting device is provided which is adapted to move relative to each other movable, adjacent basic vessel parts against each other. The invention further relates to an RH plant comprising such a vacuum treatment vessel.

Description

The invention relates to a vacuum treatment vessel for treating a molten metal, in particular for an RH plant, comprising a base vessel with a treatment space and at least two immersion tubes arranged on the base vessel and connected to the treatment space. The invention further relates to an RH plant with such a vacuum treatment vessel.

Vacuum treatment vessels for the treatment of molten metals, in particular for RH plants (RH = Ruhrstahl-Heraeus), are known, see for example the DE 10 2009 039 260 A1 ,

Vacuum treatment vessels serve to metallurgically treat a molten metal, in particular a molten steel, in an RH process in order to degas the melt and furthermore also to decarburize it. The molten metal is usually provided in a pan. A vacuum treatment vessel usually has a treatment space and at least two immersion tubes connected thereto, which dip into the molten metal. After immersing the dip tubes in the molten metal, the treatment chamber is evacuated by means of a vacuum pump and a subset of the molten metal is drawn via the dip tubes into the treatment space in the interior of the vacuum treatment vessel. By blowing an inert gas into a part of the dip tubes, wherein the inert gases rises in the molten metal and enters the treatment room, a circulation of the molten metal is generated from the pan in the fumigated dip tube, in the treatment vessel and the further dip tube back into the pan. In the treatment room, oxygen is usually supplied permanently via a lance (so-called RH-OB method, with OB = oxygen blowing or oxygen blowing). The metal melt is degassed due to the vacuum, especially of hydrogen, and decarburized, wherein the oxygen reacts with the carbon in the melt to form carbon dioxide and / or carbon monoxide. The resulting exhaust gases are removed via the vacuum pump from the treatment room.

There are various ways to immerse the dip tubes in the molten metal.

So hoists or winch systems for lifting the pan containing the molten metal are known, which raise the arranged below a permanently installed vacuum treatment vessel pan until the dip tubes dip into the molten metal, see for example DE 10 2006 026 330 B3 ,

Furthermore, systems for lifting the pan including a ladle carriage are known, in which the pan is transported. Such systems require powerful lifting mechanisms, since the load to be lifted, including the ladle, the molten metal and possibly the ladle cart, is considerable.

Winding systems are also known with which the vacuum treatment vessel can be moved while the pan remains in position under the vacuum treatment vessel. However, after the vacuum treatment vessel is connected to the vacuum pump or vacuum pumps via a temperature resistant exhaust pipe system and there is still supply of inert gas and oxygen, movement of the vacuum treatment vessel is technically more problematic than raising the pan.

It is therefore an object of the invention to simplify the required merging of molten metal and dip tubes.

The object is achieved by a vacuum treatment vessel for treating a molten metal comprising a base vessel having a treatment space and at least two immersion tubes arranged on the base vessel and connected to the treatment space, in which the basic vessel is designed in two or more parts at least two basic vessel parts are formed, which are movable relative to each other and gas-tight connected, wherein at least the base vessel part comprising the dip tubes is movable, and further wherein at least one lifting device is provided, which is arranged to move relative to each other movable, adjacent basic vessel parts against each other.

The vacuum treatment vessel according to the invention allows a particularly simple and effective way to bring the dip tubes in contact with a molten metal. The fact that at least the base vessel part of the basic vessel comprising the dip tubes is movable, while other basic vessel parts can be immobile or only limited mobility, the integration into an RH plant can be realized without any problems. Since only the one or more movable base vessel parts must be moved by the at least one lifting device, which have a relatively low mass, the movement is performed by low power actuators.

Such a vacuum treatment vessel is thus used in particular in an RH plant.

It has proven particularly useful if the basic vessel is divided horizontally into two or more basic vessel parts, which are telescopically telescopically slidable. This allows a space-saving arrangement and the possibility of realizing a simple gas-tight seal between the base vessel parts.

Relatively mutually movable, adjacent basic vessel parts are connected to each other in a gas-tight manner, in particular via a sealing arrangement. The sealing arrangement is preferably formed by an inflation seal, in particular in combination with a compensator device. An inflation seal is understood here to mean a contact seal comprising a movable membrane, for example of stainless steel, which deflects by applying a gas pressure becomes. The membrane is pressed against the base vessel part against which it is intended to be sealed. A compensator means a flexible connection between a movable base vessel part and the inflation seal, which helps to form a gas-tight space in the region of the sealing arrangement between the inflation seal and the movable base vessel part. A suitable compensator device is formed, for example, by a metal tube which can be extended in an accordion-like manner in the direction of its tube longitudinal axis and can be pushed together.

Preferably, the base vessel is divided horizontally into an upper base vessel part and a lower base vessel part, wherein only the lower base vessel part comprising the dip tubes is vertically movable. So only a single annular gas-tight seal between the upper and lower base vessel part is required. The upper base vessel part and the lower base vessel part preferably have different diameters, wherein the upper base vessel part and the lower base vessel part are telescopically slidable. In particular, the upper base vessel part has an outer diameter which is smaller than an inner diameter of the lower base vessel part, wherein the lower base vessel part can be pushed over the upper base vessel part in a space-saving manner.

In a preferred embodiment of the invention, at least one lifting device per movable base vessel part is also provided, which is arranged to move relative to each other movable, adjacent basic vessel parts against each other.

In particular, a total of at least two or three lifting devices, but in particular two or three lifting devices per movable base vessel part, are present. Such a lifting device is preferably formed by a lifting cylinder, a threaded spindle drive, or a cable system. A lifting cylinder or a threaded spindle drive can be arranged with both ends of the base vessel or with one end be attached to the base vessel and with the other end to the foundation.

Particularly preferred are two lifting cylinders, which are arranged opposite each other on the outside of the base vessel. Likewise, the arrangement of three lifting cylinders has been proven, which are arranged at equal intervals on the circumference of the base vessel. One end of each lifting cylinder is fastened, for example, to the lower base vessel part and the other end of each lifting cylinder to the upper base vessel part or the foundation. Upon actuation of the lift cylinders, the lower base vessel portion is moved vertically up or down, moving the dip tubes into or out of a molten metal below.

In a preferred embodiment of the vacuum treatment vessel, each movable base vessel part can be locked via at least one locking device to an adjacent base vessel part. This can be used both for maintenance purposes and also serves for the mechanical relief of the sealing arrangement (s).

The object is further achieved by an RH plant comprising a vacuum treatment vessel according to the invention, at least one vacuum pump which is connected to the treatment space via at least one exhaust pipe, at least one inert gas supply line for introducing inert gas into the interior of at least one dip tube, and at least one oxygen supply to Supply of oxygen to the treatment room.

Such an RH plant can be operated with a particularly low energy requirement, since the usually performed lifting of the heavy and unwieldy ladle, including molten metal, is dispensed with. Incidentally, the advantages described above for the vacuum treatment vessel according to the invention itself also apply here.

The RH plant preferably further comprises a rail system for feeding a ladle carriage with a pan to the vacuum treatment vessel. Alternatively, the pan can be brought by means of a rail-independent transport car or the like to the vacuum treatment vessel.

Preferably, at least one electrical control unit for actuating the at least one lifting device is also provided in order to move the movable base vessel parts. As a result, the movement of the basic vessel parts relative to one another can in particular be carried out automatically.

FIG 1

ein Vakuumbehandlungsgefäß im Längsschnitt in einer ersten Position im Bereich einer RH-Anlage,

FIG 2

das Vakuumbehandlungsgefäß aus FIG 1 im Längsschnitt in einer zweiten Position im Bereich der RH-Anlage, und

FIG 3

einen vergrößerten Längsschnitt durch ein Grundgefäß eines Vakuumbehandlungsgefäßes im Bereich einer Dichtungsanordnung.

The FIGS. 1 to 3 should illustrate the invention by way of example. So shows

FIG. 1

a vacuum treatment vessel in longitudinal section in a first position in the region of an RH plant,

FIG. 2

the vacuum treatment vessel off FIG. 1 in longitudinal section in a second position in the area of the RH plant, and

FIG. 3

an enlarged longitudinal section through a base vessel of a vacuum treatment vessel in the region of a seal assembly.

FIG. 1 shows a first vacuum treatment vessel 1 in longitudinal section in a first position in the region of a first RH plant 100. The vacuum treatment vessel 1 is used for treating a molten metal 14, here a molten steel. It comprises a water-cooled basic vessel 1a with a treatment space 1b and two immersion tubes 1c, 1c 'arranged on the basic vessel 1a and connected to the treatment space 1b. The basic vessel 1a is here designed in two parts, wherein two basic vessel parts 1aa, 1ab are formed by a horizontal separation, which are telescopically telescoping into one another. The upper base vessel part 1aa and the lower base vessel part 1ab are movable relative to each other and gas-tight over a annular circumferential seal assembly 3a, 3b connected to each other, of which only the sectional view can be seen here. In this case, the lower base vessel part 1ab comprising the dip tubes 1c, 1c 'is movable while the upper base vessel part 1aa is arranged immovably.

The upper header tank part 1aa has an outer diameter smaller than an inner diameter of the lower header tank part 1ab, so that the lower header tank part 1ab is slidable over the upper header tank part 1aa.

The upper base vessel part 1aa and the lower base vessel part 1ab are interconnected by two lifting devices 4a, 4b in the form of electrically operated lifting cylinders. Alternatively, the lifting cylinders could also be arranged on the one hand on the lower base vessel part 1 ab and on the other hand on the foundation 16.

In addition to the vacuum processing vessel 1, the RH plant 100 includes a vacuum pump 10 connected to the treatment space 1b via an exhaust pipe 11 for discharging exhaust gas 11a, an inert gas supply pipe 5 for introducing inert gas 5a into the interior of the dip pipe 1c, and an oxygen supply pipe 6 for supplying oxygen 6a into the treatment space 1b.

Below the vacuum treatment vessel 1, a rail system 15 is arranged on the foundation 16, via which a ladle carriage 12 can be transported on rollers 12a under the vacuum treatment vessel 1. The ladle carriage 12 transports a pan 13 with the molten metal 14, wherein pan 13 and molten metal 14 are shown in the sectional view for a better overview.

When the lift cylinders are extended, the lower base vessel part 1ab moves vertically downward to a second position according to FIG FIG. 2 in which the dip tubes 1c, 1c 'dip into the molten metal 14. Same reference numerals as in FIG. 1 mark same elements. On the representation of the inert gas supply 6 but was omitted here for clarity. By introducing the inert gas 6a in the dip tube 1c (see FIG. 1 ), the molten metal 14 is circulated. The vacuum pump 10 evacuates the treatment space 1b, wherein gases, in particular hydrogen, escape from the molten metal 14 within the treatment space 1b. Blown oxygen 6a reacts with carbon in the molten metal 14 and escapes as carbon dioxide and / or carbon monoxide together with other gases as the exhaust gas 11a. When retracting the lifting cylinder, the lower base vessel part 1 ab moves together with the dip tubes 1 c, 1 c 'again vertically upward and the dip tubes 1 c, 1 c' are pulled out of the treated molten metal 14.

After only the lower base vessel part 1ab must be moved by the lifting cylinder, they can be made very small and energy-efficient.

FIG. 3 shows an enlarged longitudinal section through a base vessel 1 a of a vacuum treatment vessel in the region of a seal assembly 3. The same reference numerals as in Figures 1 and 2 identify similar elements. There are locking devices 9a, 9b rigidly connected to the lifting cylinders, in order to fix the lower base vessel part 1ab in the desired position relative to the upper base vessel part 1aa and to mechanically relieve the sealing arrangement 3 and the lifting cylinders. The sealing arrangement 3 comprises an inflation seal 7 comprising a tubular construction with a movable membrane 7a made of sheet steel and a compensator device 8 in the form of a metal hose deformable accordion-shaped in the direction of its tube longitudinal axis. In this case, the pipe construction is fastened to the locking device 9a, 9b and the membrane 7a is arranged facing the upper base vessel part 1aa. The variable-length tubular Kompensatoreinrichtung 8 connects the inflation seal 7 on all sides with the lower base vessel part 1ab. In the tube construction, a gas is injected under pressure, so that the Membrane 7a is deflected and presses in the region of the circumference of the upper base vessel part 1aa against this and thus the lower base vessel part 1ab gas-tightly connects to the upper base vessel part 1aa. Accordingly, during a movement of the lower base vessel part 1ab relative to the upper base vessel part 1aa of the lifting cylinders, the desired position - with simultaneously released locking device 9a, 9b - approached, wherein the compensator 8 is extended or shortened. Subsequently, the locking devices 9a, 9b are actuated and fixed the position. Now gas is injected into the pipe construction and the membrane 7 a pressed against the upper base vessel part 1 aa, so that a gas-tight connection between them is formed. The treatment space 1b is now sealed downwards over the molten metal 14, into which the immersion pipes, which are not visible here, the basic vessel 1a and the sealing arrangement 13, sealed from the environment and can be conveyed via the vacuum pump 10 (see FIG FIGS. 1 and 2 ) be evacuated. Alternatively to the in FIG. 3 In the embodiment shown, the inflation seal can also be arranged on the lower base vessel part 1ab, so that a compensator device 8 can be dispensed with.

The in the FIGS. 1 to 3 illustrated vacuum treatment vessels and RH systems to illustrate the invention by way of example only. Accordingly, a large number of further embodiments are possible, which are readily apparent to the person skilled in the art with knowledge of the invention.

Claims (14)

Vacuum treatment vessel (1) for treating a molten metal (14), in particular for an RH plant (100), comprising a base vessel (1a) with a treatment space (1b) and at least two arranged on the base vessel (1a) and with the treatment space (1b) connected immersion tubes (1c, 1c '), characterized in that the basic vessel (1a) is designed in two or more parts, wherein at least two basic vessel parts (1aa, 1ab) are formed, which are connected to each other movable and gas-tight, at least the Base vessel part (1ab) comprising the dip tubes (1c, 1c ') is movable, and further at least one lifting device (4a, 4b) is provided, which is arranged to move relative to each other movable, adjacent basic vessel parts (1aa, 1ab) against each other. Vacuum treatment vessel according to claim 1,
characterized in that the basic vessel (1a) is divided horizontally into two or more basic vessel parts (1aa, 1ab) which are telescopically telescopically slidable. Vacuum treatment vessel according to claim 1 or claim 2, characterized in that relative to each other movable, adjacent basic vessel parts (1aa, 1ab) via a sealing arrangement (3, 3a, 3b) are gas-tightly interconnected. Vacuum treatment vessel according to one of claims 1 to 3, characterized in that the sealing arrangement (3) is formed by an inflation seal. Vacuum treatment vessel according to one of claims 1 to 4, characterized in that the base vessel (1a) is divided horizontally into an upper base vessel part (1aa) and a lower base vessel part (1ab), wherein only the lower base vessel part (1ab) is movable. Vacuum treatment vessel according to claim 5,
characterized in that the upper base vessel portion (1aa) and the lower base vessel portion (1ab) have different diameters and that the upper base vessel portion (1aa) and the lower base vessel portion (1ab) are telescopically slidable. Vacuum treatment vessel according to claim 6,
characterized in that the upper base vessel part (1aa) has an outer diameter smaller than an inner diameter of the lower basic vessel part (1ab), the lower basic vessel part (1ab) being slidable over the upper basic vessel part (1aa). Vacuum treatment vessel according to one of claims 1 to 7, characterized in that further at least one lifting device (4a, 4b) per movable base vessel part (1ab) is provided, which is arranged to move relative to each other, mutually adjacent basic vessel parts (1aa, 1ab) against each other , Vacuum treatment vessel according to claim 8,
characterized in that at least two lifting devices (4a, 4b) per movable base vessel part (1ab) are present. Vacuum treatment vessel according to claim 8 or claim 9, characterized in that the lifting device (4a, 4b) is formed by a lifting cylinder, a threaded spindle drive or a cable system. Vacuum treatment vessel according to one of claims 1 to 7, characterized in that each movable base vessel part (1ab) via at least one locking device (9a, 9b) on an adjacent base vessel part (1aa) is lockable. RH plant (100, 100 ') comprising a vacuum treatment vessel (1, 1') according to one of claims 1 to 11, further comprising at least one vacuum pump (10) connected to the treatment space (1b) is connected via at least one exhaust pipe (11), at least one inert gas supply line (5) for introducing inert gas (5a) into the interior of at least one dip tube (1c), and at least one oxygen supply line (6) for supplying oxygen (6a) into the treatment room (1b). RH plant according to claim 12,
further comprising a ladle carriage (12) with pan (13) and a rail system (15) for feeding the ladle carriage (12) with ladle (13) to the vacuum treatment vessel (1, 1 ') is present. RH plant according to claim 12 or claim 13,
wherein furthermore at least one electrical control unit for actuating the at least one lifting device (4a, 4b) is present.

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