WO2011098309A1

WO2011098309A1 - Metallurgical vessel and method for producing a wall of the vessel

Info

Publication number: WO2011098309A1
Application number: PCT/EP2011/050254
Authority: WO
Inventors: Dirk Lieftucht; Matthias Arzberger
Original assignee: Sms Siemag Ag
Priority date: 2010-02-09
Filing date: 2011-01-11
Publication date: 2011-08-18
Also published as: EP2533920B1; CN102740995A; CN102740995B; EP2533920A1; ES2523772T3; DE102010034729A1

Abstract

The invention relates to a metallurgical vessel having a hollow chamber for treating a first liquid metal or for liquefying a metal, said vessel comprising cooled wall plates (1) having a hot side facing the hollow chamber and a cold side facing away from the hollow chamber made of a second metal and which is provided with optical waveguides (5, 6, 7) for detecting data of the metallurgical vessel or of the first metal, characterized in that the optical waveguides (5, 6, 7) are arranged in the region of the hot side close to the surface.

Description

Metallurgical vessel and method for producing a wall of the vessel

The invention relates to a metallurgical vessel having a cavity for treating a first liquid metal or for liquefying a metal, the vessel comprising a coolable wall with a hot side facing the cavity and a cold side facing away from the cavity made of a second metal, and wherein optical fibers for Collection of data of the metallurgical vessel or the first metal are introduced into the wall of the vessel. In this case, the first metal is especially steel, but it may also be another metal. The second metal is in particular copper, although it is also possible to provide another metal. The invention further relates to a method for producing a wall for the metallurgical vessel and the use of optical waveguides in the wall of the vessel.

For steelmaking, a number of devices are known which use predominantly hot, molten pig iron in combination with scrap, ore, sponge iron and other feedstocks via blast furnace and converter. Likewise, melting vessels are used, for example electric arc furnaces, in which mainly cold or preheated starting materials such as scrap and sponge iron are used. Both molds and electric arc furnaces and other devices for melting or reserving molten metal are referred to as metallurgical vessels. DE 10 2008 060 507 A1 describes the measurement of the temperature in a mold of a casting plant with the aid of a fiber optic measuring method. In this case, sensors for measuring the temperature in at least one copper plate in the wall of the mold are used. The sensors are connected to a temperature sensing system.

As sensors optical fibers are used, is passed through the laser light. On the outside of the copper plates grooves are formed, in which the optical fibers are laid. The temperature detection by means of optical fibers allows a significantly lower cable costs than the use of thermocouples in the mold. In addition, considerably less labor and expense is required to install the fibers in the mold copper plate. The use of the optical waveguides also allows a higher spatial resolution, as they can be achieved when using thermocouples, which are used in drilling. An optical fiber can replace more than a hundred thermocouples and their cables.

The optical waveguides are, for example meandering between the cooling channels on the back, d. H. on the cold side, a copper plate of a mold laid in grooves. The optical waveguides can be cast in the grooves by means of cast resin. Closure by other components or by electroplated layers is also known.

DE 1 0 2008 006 965 A1 discloses a method for determining a radiation measure for a thermal radiation emanating from an arc burning between an electrode and melted material in an arc furnace for the production of liquid metal, generally steel, which is then used for Use comes when the radiation is limited to a limitation of the arc oven hits.

In the electric arc furnace, liquid metal produced from a solid melt, such as scrap or reduced iron, is produced using further additives. For this purpose, energy for melting the melt is introduced into the arc furnace by means of one or more electrodes, usually in the form of an arc between the electrode and the melt. In order for the melting to be as efficient as possible, attempts are made to introduce as much as possible of the total energy provided by the arc into the melt. Melted material is to be understood as melting solid, liquid metal and / or also slag.

Due to the usual operation in today's electric arc furnaces, however, it can happen that the arc burns freely during the melting process, d. H. the thermal radiation generated by the arc, which is formed between the electrode and the melt, largely reaches a boundary of the arc furnace, in particular a cooled wall of the arc furnace. As a result, the energy consumption of the furnace increases by one hand, the energy of the arc furnace is introduced only to a limited extent in the melt and on the other hand, if necessary, the cooling capacity for cooling the furnace walls must be increased to protect the wall / Kupferstaves.

In the known method, an electrode current supplied to the electrode is detected, whereby structure-borne sound oscillations of the arc furnace are detected and a current evaluation signal assigned to a frequency range of the detected electrode current is determined from the detected electrode current, wherein a vibration test results from the recorded structure-borne sound vibrations. evaluation signal is determined, which is associated with a frequency range of the structure-borne sound vibrations. In this case, a quotient of the vibration evaluation signal and the current evaluation signal for at least one detected frequency of the detected electrode current and the detected structure-borne sound vibrations is formed as a measure of the thermal oscillation in order to determine the radiation measurement.

On a wall or on the panels of the furnace vessel, d. H. On the outer boundary of the furnace vessel structure-borne sound sensors for detecting vibrations on the furnace vessel are arranged. The signals transmitted by them are preferably conducted at least partially via an optical waveguide.

It is known, optical waveguide on the side facing away from the cavity containing the liquid metal, d. H. the cold side of the copper wall plates in grooves. When introducing from the cold side, rise times are often associated with temperature changes, ie. H. the times to reach a 68% value of the temperature value to be reached, of two or three seconds before. Such long rise times disqualify the optical fibers for the task of Gießspiegelregelung. In this case, it is therefore necessary to use radiometric systems which use radioactive radiation in which rise times of one-half to one second can be achieved.

It is the object of the invention to improve a known metallurgical vessel of the type mentioned at the outset and a known method for producing a wall for the vessel, as well as the use of optical waveguides in the wall of the vessel so that a more exact detection of temperatures is achieved. temperature or strain data on the vessel or metal in the vessel.

According to the invention, this object is achieved in that the optical waveguides are arranged near the surface in the region of the hot side.

The term metallurgical vessel for the purposes of the present invention includes all types of metallurgical vessels, including furnaces, in particular E- lektrolichtbogenöfen, and molds, in particular for continuous casting.

The term wall in the sense of the present invention also includes individual wall elements, e.g. Wall panels, as part of an entire vessel wall. Conversely, the term wall plate is to be understood both as a single element as well as the entire wall of the vessel.

The inventive introduction of optical fibers in the walls of the electric arc furnace, the temperatures or the expansion or vibration behavior of the metallurgical vessel can be represented on the hot side in different heights of the vessel. In this case, dynamic changes due to the process, for example due to flow changes in the melt, are also detected. The concept allows a representation of the thermal and mechanical loading of the wall of the vessel in any operating condition, even in time dependence. Thus, it is also possible to search specifically for (process) errors, such as longitudinal cracks in the wall or caking of melt on the hot side, as a cause for characteristic signatures on the subsequent cast product. In this new concept, the optical waveguides are not, as previously known, from the cold water-flowed cold side, but introduced directly from the thermally stressed hot side in the wall of the vessel. This allows very timely monitoring of the staves against overload situations. If the optical fiber LWL in the copper stave indicates an incipient overheating, the heating power of the electrode can be reduced. Due to the accurate measurement, the arc furnace can be operated closer to the operating limit with more heating power, since no unnecessarily high safety reserve to protect the staves is necessary.

For this purpose, a continuous groove is milled on the hot side, which is later closed on the hot side by a filler piece of the base material of the hot side. This filler is preferably fused by the friction stir welding again with the body. In this case, the groove depth is dimensioned such that the thermal stress caused by the welding process can not damage the optical waveguide.

For the use of a casting mold, this concept has the advantage that the measuring fiber is arranged very close to the region in which the casting process takes place. As a result, optical fibers can be used for temperature measurement or strain measurement without requiring too long rise or fall times in cycles. In the set of the fiber Bragg method for measuring the temperature of optical waveguides laid according to the invention, rise times of only 0.1 s are achieved when using a sufficiently thin cladding tube which surrounds the optical waveguide. This means that when introducing an optical waveguide surrounded by a cladding tube in the groove of a hot side / copper plate still an increase in dead time or an additional rise time of another 0.25 s can be accepted without obtaining a result worse than in a known radiometric method. By the invention, such a good accuracy of measurement can be realized with low dead and rise times, if the grooves in which the optical waveguides lie, have only a small depth of about 3 - 1 2 mm. That is, the optical waveguides are according to the invention, for example, in the range of 3 - 12 mm behind the hot side. By milling, grooves are produced, for example by means of a disc milling cutter, which have a width of one to two millimeters. In these, the enveloped with cladding optical fiber h can be inserted. Subsequently, the grooves are preferably filled by matched to the width of the grooves metal strips as patches. Finally, the metal strips are connected at their side edges with the material of the copper plates. This can be done by a variety of technologies, such as welding or soldering. Further advantageous developments of the invention will become apparent from the dependent claims, the description and the drawings.

Advantageously, the patches, which close the grooves, made of the same material as the wall panels.

Advantageously, it can also be provided that the grooves have a cross section tapering towards the groove base. This prevents that during friction stir welding, a bolt driving with pressure over the weld metal can depress the filler piece too deeply and thereby crush the optical waveguide jacket tube. For this purpose, the grooves advantageously have an at least substantially trapezoidal cross-section. Due to the trapezoidal cross-section, the depression of the filler and the crushing of the cladding tube can be prevented.

It is understood that the filler pieces preferably have a cross-section adapted to the grooves, in particular a likewise trapezoidal cross-section.

Preferably, the filler pieces have a slight undersize relative to the grooves, in particular in the region which adjoins the surface of the wall pieces. This makes it possible that the filler can be connected by mechanical action, in particular by rolling or welding, with the material of the wall panels without damaging the optical waveguide cladding at the bottom of the groove.

The connection between the filler pieces and the material of the wall panels surrounding them laterally is preferably carried out by a welding operation, preferably by friction welding, in particular by friction stir welding.

Advantageously, but not necessarily, the optical waveguides in cladding tubes, in particular made of metal, are introduced. For this purpose, it is also advantageous to provide that the filler pieces and the wall panels are coated on their externally accessible surfaces with a layer of nickel or chromium.

As an alternative to introducing the optical waveguides into grooves and then filling them with filler pieces and using friction welding, it can also be provided according to the invention in another preferred embodiment that the optical waveguides are introduced into bores which run parallel to the hot-side surface of the wall plates and which are produced for example by laser technology.

Preferably, the optical fibers have a diameter of about 0.15 mm. The matching sheaths have a diameter of about 0.5 to 1 mm. Preferably, the patches have a width of 1 to 2 mm.

The optical fibers can be used metrologically in many ways. Depending on their purpose they are loosely in the grooves or holes, especially for temperature measurement, because for the temperature measurement, it is important that the optical fibers can contract or expand unhindered themselves due to a change in temperature.

The optical waveguides are preferably laid in the vicinity of the copper staves. This has the advantage that the heating power of the electric de (n) of the furnace can already be reduced again as soon as the optical waveguides allow a failure of the staves in the near future.

In contrast, it is important for a strain measurement that the optical waveguides are at least selectively, but preferably firmly connected over its entire length with the surrounding material of the wall and / or with the filler pieces. This form of attachment is required so that expansion of the vessel can be transmitted directly to the optical fiber and the optical fiber can emit signals representing the strains of the metallurgical vessel. Also, the temporal course of strains, vibrations and / or temperatures, as they are each detected with the optical waveguides, can be recorded and evaluated. It is understood that in the same metallurgical vessel according to their different uses both loosely laid and glued optical waveguides can be present in the grooves or holes on the hot side of the wall panels.

The invention also relates to the use of optical waveguides in walls of metallurgical vessels. In this case, it is provided according to the invention that the optical waveguides measure the temperature of the wall, the molten metal of the first metal in the vessel or mechanical strains or vibrations of the wall. Preferably, the data are used, for example, to control the casting level.

The invention also relates to a method for producing a wall plate comprising a wall of a metallurgical vessel. For this purpose, According to provision provided that on the hot side of the wall grooves are produced by material removal, in particular by milling, that optical fibers are placed in the grooves, that the grooves closed by patches and then the filler by a welding process, in particular by friction stir welding, with the material of Wall panels are connected.

The invention will be explained in more detail in exemplary embodiments with reference to the figures. Show it:

1 is a perspective plan view of a wall plate of a casting mold, are introduced into the grooves for receiving optical waveguides,

Fig. 2 shows a filler and a plate having a groove in which the filler is used, in each case in cross section, and

Fig. 3 is a side perspective view of another wall plate, in which a closed with a trapezoidal filler and an optical waveguide receiving groove is introduced, in conjunction with a schematically illustrated arrangement for friction stir welding.

A wall plate 1 (FIG. 1) of a metallurgical vessel, for example a mold for casting metal, in particular steel, preferably exists made of copper and has on the side facing the casting chamber receiving the liquid metal, the so-called hot side, d. H . in the representation on the upper side, grooves 2, 3 and 4, which have a rectangular, square or trapezoidal cross section and whose base is preferably rounded. In the grooves 2, 3 and 4, optical fibers 5, 6 and 7 are inserted into it. From the top side / the hot side, the optical waveguides 5, 6 and 7 in the grooves are covered in each case with filling pieces 8, 9 and 10, respectively. In addition, for fixing either only at the outer lateral ends 1 1, 12 or, also in the region between the two ends 1 1, 12 protruding, hold-down 13, 14 and 15 are provided, the optical fibers 5 to 7 and / or Fastening pieces 8 to 1 0 lying on them, while they are connected by a Reibschwei ßvorgang with the laterally adjoining them areas 16, 17, 18 and 19 of the wall plate 1.

The optical waveguides 5 to 7 consist of an optically conductive material having a refractive index which decreases in cross-section from the inside to the outside; they are preferably each received by metallic sheaths or sleeves and can endure temperature measurement temperatures up to 600 ° C as a continuous load. On its back, the wall plate 1 is flowed through by cooling water. The cooling water flows through channels (not shown).

The optical waveguides 5 to 7 have at the end lens plug to decouple the light waves and supply them to an evaluation unit. As a result of the fact that the light waves are conducted via lens plugs from the housing of the component in the respective measuring position to the evaluation unit, a robust signal transmission is achieved. The optical waveguides 5 to 7 have a diameter of, for example, 0.15 mm without the cladding tube and including the Cladding tube, for example, 1 mm. The measurement method used is a fiber Bragg grating measuring method (FBG = Fiber Bragg Grating) method and / or the OTDR method (OTDR = Optical Time Domain Reflectometry) and the OFDR method (Optical Frequency Domain Reflectometry).

The filler pieces 8, 9, 1 0, as shown in FIG. 2 illustrated by the filler 8, a preferably trapezoidal cross-section 20. In this case, side walls 21, 22 with an upper edge 23 of the filler piece 8 preferably form the same obtuse angle α, which is also present between the side walls 23, 24 of the groove 2 and the regions 1 6, 1 7 adjoining them laterally. On the bottom 25 of the groove 2, which is preferably rounded, lies the optical waveguide 5 surrounded by a cladding tube 26. The filler 8 may also have a slight undersize relative to the groove 2. It is then mechanically inserted into the groove 2h and, for example, welded or brazed to the regions 1 6, 1 7 surrounding the groove 2.

When a filling piece 27 (FIG. 3) is adapted sufficiently precisely to the shape of a groove 28 in a workpiece 29, for example a copper plate for a casting mold, which it is intended to cover from the hot side, the filling piece 27, after it has become has been put into the groove 28, preferably by friction stir welding with lateral portions 30, 31 connected. For this purpose, a Rührschweißgerät 32 is guided above the wall plate 1 in the direction of an arrow A over the course of the groove 28 on the filler 27, wherein a mounted on a tool shoulder 33 welding pin 34 in contact with the filler 27 simultaneously performs rotational movements. This heat up Filler 27 and the areas 30, 31 so strong that they enter into a material connection with each other due to the frictional heat, which has a high stability.

The introduction of the optical waveguides in the region of cooling elements, e.g. so- nant Kupferstaves, in the hot side of the metallurgical vessel advantageously allows a very fast and efficient way of fiber introduction.

The time profile of the temperature of the wall of the vessel or of the molten metal in the vessel and / or the time profile of the expansion of the vessel can be detected with the aid of the optical waveguide and used, for example, to optimize / increase the electrode power. The electrode power is controlled in accordance with the considered temporal courses so that the walls of the vessel are not damaged. In particular, by evaluating the time profiles, the failure limit of the vessel can be determined and the electrical power of the electrodes can be reduced in good time before reaching the failure limit.

LIST OF REFERENCE NUMBERS

1 wall

2 groove

1 0 3 groove

4 groove

5 optical fibers

6 optical fibers

7 optical fibers

1 5 8 filler

9 filler

10 filler

1 1 end

12 end

20 13 hold-downs

14 hold downs

15 hold-downs

16 area

17 area

25 18 area

19 area

20 cross section

21 sidewall

22 side wall

30 23 side wall

24 side wall 25 reason

26 cladding tube

27 filler

28 groove

29 workpiece

30 area

31 area

32 stir-welding device

33 Tool shoulder

34 welding pin

35 melt

36 lance

37 lance tube

38 lances head

39 application device

40 scrapers

41 supply line

Claims

claims

1 . Metallurgical vessel having a cavity for treating a first liquid metal or for liquefying a metal, wherein the vessel comprises a coolable wall (1) with a hot side facing the cavity and a cold side facing away from the cavity made of a second metal and wherein the wall (1) equipped with optical waveguides (5, 6, 7) for detecting data of the metallurgical vessel or of the first metal, characterized in that the optical waveguides (5, 6, 7) are arranged near the surface in the region of the hot side.

2. A vessel according to claim 1, characterized in that the optical waveguides (5, 6, 7) in grooves (2, 3, 4, 28) are introduced, which are introduced from the hot side into the wall (1), wherein the Grooves (2, 3, 4, 28) are sealed with the introduced optical waveguides by filling pieces (8, 9, 10, 27) on the hot side.

3. vessel according to claim 2, characterized the filler pieces (8, 9, 10, 27) consist of the same material as the wall (1).

4. Vessel according to claim 2 or 3, characterized in that the grooves (2, 3, 4; 28) have a groove bottom (25) tapering towards its cross-section.

5. A vessel according to claim 4, characterized in that the grooves (2, 3, 4, 28) have an at least substantially trapezoidal cross-section.

6. A vessel according to claim 4 or 5, characterized in that the filling pieces (8, 9, 10, 27) have a cross section adapted to the grooves (2, 3, 4, 28), in particular a likewise trapezoidal cross section.

7. A vessel according to any one of claims 2 to 6, characterized the filler pieces (8, 9, 10, 27) have a slight undersize with respect to the grooves (2, 3, 4, 28), in particular in the region adjoining the surface of the adjacent wall regions.

8. A vessel according to any one of claims 2 to 7, characterized in that the filling pieces (8, 9, 10, 27) have a width of 1 to 2 mm.

9. A vessel according to any one of claims 2 to 8, characterized in that the wall with the filler pieces (8, 9, 10, 27) is coated on the hot side with a layer of nickel or chromium.

10. A vessel according to claim 1, characterized in that the optical waveguides (5, 6, 7) are introduced into bores which extend parallel to the hot side in the wall (1).

1 1. Container according to one of claims 1 to 10, characterized the optical waveguides (5, 6, 7) are incorporated in the grooves or bores in cladding tubes, in particular of metal.

A vessel according to claim 10, characterized in that the cladding tubes (26) have a diameter of about 0.5 - 1 mm.

Container according to one of claims 1 to 12, characterized in that the optical waveguides (5, 6, 7) have a diameter of about 0.15 mm.

Vessel according to one of claims 1 to 13, characterized in that the optical waveguides (5, 6, 7) for temperature measurement loosely in the grooves (2, 3, 4, 28), bores or sheaths are laid, or for detecting strains of the metallurgical vessel punctually or over its entire length with the surrounding material of the wall, the filler pieces and / or the cladding tubes are firmly connected, wherein the cladding tubes for strain measurement in turn are connected to the wall.

15. Use of an optical waveguide in the wall of a metallurgical vessel according to one of claims 1 to 14, characterized in that the optical waveguide (5, 6, 7) is used to the temperature of the wall of the vessel, or the temperature of the molten metal of the first Metal in the vessel, or to measure expansions of the vessel.

16. Use according to claim 15, characterized in that the time profile of the temperature or the strains is detected, wherein the time course of the measured strains of the vessel represents the vibration behavior of the vessel.

17. Use according to claim 15 or 16, characterized in that the detected data are used to control the casting level.

18. Use according to claim 15, characterized in that the temporal courses of the temperature of the wall of the vessel or molten metal or of the expansions of the vessel are recorded as data can be used to optimize / increase the electrode performance without damaging the walls of the vessel or shortly before reaching the Verssagensgrenze can be limited due to the optical fiber measurements, the electrode power.

19. A method for producing a wall of a metallurgical vessel, the wall (1) having a hot side and a cold side, optical waveguides (5, 6, 7) being introduced into the wall for detecting data; characterized in that the introduction of the optical waveguides comprises the following steps:

On the hot side: introduction of grooves (2, 3, 4, 28) into the wall (1) by material removal, in particular by milling,

Inserting the optical waveguide (5, 6, 7) in the grooves (2, 3, 4, 28), and

Closing the grooves (2, 3, 4; 28) on the hot side by filling pieces (8, 9, 10, 27).

A method according to claim 19, characterized in that the filler pieces (8, 9, 10, 27) are connected by mechanical action, in particular by soldering or welding, with the material of the wall. A method according to claim 20, characterized in that the welding operation by friction welding, in particular by friction stir welding, takes place.