WO2000009767A1 - Sonde effilee pour controler le niveau du moule - Google Patents

Sonde effilee pour controler le niveau du moule Download PDF

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Publication number
WO2000009767A1
WO2000009767A1 PCT/US1999/017566 US9917566W WO0009767A1 WO 2000009767 A1 WO2000009767 A1 WO 2000009767A1 US 9917566 W US9917566 W US 9917566W WO 0009767 A1 WO0009767 A1 WO 0009767A1
Authority
WO
WIPO (PCT)
Prior art keywords
probe
slag
distal end
vessel
electrical
Prior art date
Application number
PCT/US1999/017566
Other languages
English (en)
Inventor
John Usher
Original Assignee
Vesuvius Crucible Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vesuvius Crucible Company filed Critical Vesuvius Crucible Company
Priority to AU53336/99A priority Critical patent/AU5333699A/en
Publication of WO2000009767A1 publication Critical patent/WO2000009767A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D2/00—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass
    • B22D2/003—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass for the level of the molten metal
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/4673—Measuring and sampling devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
    • G01F23/242—Mounting arrangements for electrodes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
    • G01F23/243—Schematic arrangements of probes combined with measuring circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
    • G01F25/20—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume of apparatus for measuring liquid level

Definitions

  • This invention relates to both a device and method for measuring the depth of molten steels and slags in metallurgical vessels.
  • the invention is particularly concerned with detecting the menisci or depths of steel or slag by measuring the impedance of a probe member comprising an electrically conductive ceramic.
  • molten steel is transferred from one metallurgical vessel into another and finally into a mold. Throughout the process, shielding the molten steel from air is important to prevent deleterious oxidation. While in metallurgical vessels, a floating a layer of slag on the surface of the molten steel reduces contact of the steel with air, thereby reducing oxidation. Slag comprises a mixture of impurities, which separate from the steel during the refining process, and non-metallic fluxes, which are intentionally added to facilitate casting and reduce oxidation. At casting temperatures, slag itself exists as both a solid and a liquid.
  • Solid slag includes less dense compounds and floats on top of the molten slag, which in turn floats on the molten steel .
  • the chemical and physical properties of the liquid slag, including its depth, may significantly affect final steel product by influencing the actual steel meniscus within the metallurgical vessel.
  • Metallurgical vessels typically have a bottom aperture through which the molten steel may flow.
  • the slag floats on the steel surface as the steel exits the aperture. In this fashion, slag continues to shield the molten steel from oxidation throughout the casting process.
  • the floating slag must not contaminate the steel exiting the bottom aperture. Slag contamination can seriously degrade steel quality, interfere with casting, and even generate explosive reactions. Slag must, therefore, be kept from draining through the bottom aperture .
  • Knowing the depth or meniscus of slag or molten steel during the draining of a metallurgical vessel is essential to maximizing steel output, and reducing oxidation and slag contamination.
  • the depth of steel in the metallurgical vessel can be kept high enough that slag contamination is not problematic.
  • the metallurgical vessel may need to be taken out of service for maintenance or repairs. In such situations, it is desirable to drain the molten steel from the vessel to avoid waste. Care must be taken to avoid slag contamination as the steel level decreases .
  • the depth or meniscus of molten steel beneath the slag may be ascertained visually. Visual observation is, at best, a crude approximation. Further exacerbating the problem, slag thickness is not necessarily constant throughout the casting process. Allowing for these approximations and the danger of permitting slag to contaminate the steel, an operator must leave more than a minimum amount of steel in the vessel .
  • U.S. Pat. No. 4,365,788 describes a plurality of combination electrodes embedded in a wall of a metallurgical vessel. Measuring the electrical resistance of the electrodes can distinguish between steel and slag. Such combination electrodes contain multiple components that must be assembled and then imbedded in a vessel wall. Failure of an electrode requires shutting down the casting. These limitations obviously increase the cost of production.
  • U.S. Pat. No. 5,827,474 teaches an electrically conductive ceramic probe disposed in a metallurgical vessel .
  • the probe is moved vertically in the vessel while measuring the electrical potential of the probe. Electrical potential changes as the probe is lowered through the slag and into the steel. Alternatively, the probe may be fixed while the molten steel level changes. A defective probe can easily be changed. An operator recognizes the steel-slag interface as a discontinuous change in the measured electrical properties . This probe cannot readily distinguish between solid slag and liquid slag.
  • Prior art probes can detect the steel-slag interface but do so via a discontinuous change in measured electrical properties. Such a change gives an operator no warning of the proximity of the steel-slag interface.
  • Prior art probes also do not differentiate between solid slag and liquid slag. None reliably measure the thickness of slag floating on the steel surface.
  • the present invention relates to a device and a method for determining the depth or meniscus of steel or slag in a metallurgical vessel.
  • the invention comprises at least one electrically conductive probe, a means for measuring the impedance and electrical potential of the probe, and a means for vertically positioning the probe within a metallurgical vessel.
  • the device is described as a probe comprising a refractory ceramic material with a tapered distal end that is immersed in the metallurgical vessel.
  • the probe also has a proximal end for connecting to the measuring means.
  • the tapered distal end of the electrically conductive ceramic probe is described as improving sensitivity and response to impedance changes in the probe.
  • the tapered end is also described as more accurately determining the menisci of steel and slag, and of distinguishing solid slag from liquid slag.
  • Another embodiment of the invention describes a plurality of stationary, electrically conductive ceramic probes, where each one is disposed at different vertical heights within a metallurgical vessel.
  • a plurality of stationary probes may be used in place of a vertically positionable probe.
  • the method of the invention is described as measuring the electrical output from at least one electrically conductive ceramic probe having a tapered distal end.
  • the method describes using changes in the impedance and electrical potential of the probe to determine the menisci and depths of steel, liquid slag and solid slag.
  • the method includes vertically moving the probe while measuring electrical properties.
  • the method uses a plurality of stationary probes disposed at various elevations in place of a vertically movable probe. DESCRIPTION OF THE DRAWINGS
  • FIG. 1 shows a metallurgical vessel having a tapered probe of the present invention attached to a means for detecting electrical potential and impedance.
  • FIG. 2 shows a metallurgical vessel having a prior art probe attached to a means for detecting electrical potential and impedance.
  • FIG. 3 shows a metallurgical vessel having a plurality of probes of the present invention, each probe attached to a means for detecting electrical potential and impedance. Dashed lines indicate circuits omitted for clarity.
  • FIG. 4 compares the change in electrical potential between a probe of the present invention and a probe of the prior art, in particular, the figure shows a continuous and a discontinuous transition for the present invention and the prior art, respectively.
  • FIG. 1 shows a device of the present invention.
  • An electrically conductive ceramic probe 1 having a conically shaped distal end 2 is immersed in a metallurgical vessel 3 containing molten steel 4 and a slag layer 5.
  • the distal end 2 is defined by a cone angle 13.
  • An electrical lead 6 is attached to the proximal end 7 of the probe 1, and connected to at least one meter 8.
  • the meter measures impedance and electrical potential, and comprises a voltmeter 14 with an impedance meter 15 connected in parallel to the input and output terminal of the volt meter 14.
  • the molten steel 4 exits through a nozzle 9 located at the bottom of the metallurgical vessel 3.
  • the slag layer 5 includes a solid slag layer 10 floating on a liquid slag layer 11.
  • An interface 12 exists between the slag and the molten steel .
  • a prior art probe is shown in FIG. 2.
  • An electrically conductive ceramic probe 21 having a blunt distal end 22 is immersed in a metallurgical vessel 3 containing molten steel 4 and a slag layer 5.
  • An electrical lead 6 is attached to the proximal end 27 of the probe 21, and connected to meter 8, capable of measuring impedance and electrical potential, as described above.
  • the slag layer 5 includes a solid layer 10 floating on a liquid layer 11 with an interface 12 between the slag and the steel .
  • the device of the present invention comprises a probe having distal and proximal ends, an electrical conductor, and a meter or meters for measuring impedance and electrical potential .
  • the interrelationship between the various system components is described in U.S. Pat. No. 5,827,474, the entire specification of which is incorporated herein by reference.
  • the probe comprises an electrically conductive ceramic with an elongated body having a tapered distal end, which may be immersed in molten steel.
  • the distal end will taper continuously, and most preferably will be substantially conical .
  • the electrical conductor connects the proximal end of the probe to the electrical meter.
  • the ceramic comprises an electrically conductive refractory material, typically a refractory oxide and graphite.
  • the refractory oxide may be a metal oxide or semimetallic oxide, including, for example, alumina, silica, magnesia, zirconia and other refractory ceramic oxides. Such oxides are rendered electrically conductive by mixing with between 5 weight percent and 50 wt . % graphite or other form of carbon.
  • Probes comprising zirconia/graphite are effective where highly erosive slags are present. Most commonly, the probe will comprise alumina/graphite, with 30 wt . % to 95 wt . % alumina and 5 wt . % to 50 wt .
  • the tapered end of the probe may be of any shape so long as the cross-sectional area of the end is substantially decreasing to the tip.
  • the cross-sectional area will continuously decrease, and most preferably the area will continuously decrease at a constant rate so that the distal end is conical .
  • the particular shape of the tapered end and the degree of taper will affect the abruptness of the measured changes in electrical properties.
  • a conical distal end of the probe should have a cone angle between 5° and 45° with a cone length of greater than about 2 inches, and preferably between about 6 inches and 12 inches .
  • a smaller cone angle, corresponding to a longer conical end, will produce more gradual changes in electrical properties.
  • the electrical potential as a function of the depth of the probe as measured with a conical probe changes more gradually near the steel-slag interface than a comparable blunt end probe .
  • the blunt end probe experiences a discontinuous change in electrical potential upon transecting the steel-slag interface.
  • an operator may anticipate the steel-slag interface or the interface between the solid slag and liquid slag. Prior art blunt end probes do not warn of an impending interface . Consequently, tapered probes permit greater confidence in operating near the steel-slag interface.
  • the probe of the present invention will also have a proximal end to which a first end of an electrical conductor may be fixed, typically with an electrically conductive refractory mortar.
  • the second end of the electrical conductor is attached to a means for measuring electrical potential and impedance.
  • the means comprises a voltmeter with an impedance meter connected in parallel to the voltmeter.
  • the meters may be connected to data storage and computer circuitry, which automatically determine the menisci or depths of steel, liquid slag or solid slag remaining in the metallurgical vessel .
  • the circuitry may be connected to a vertical positioning means that controls the height of the probe in the vessel. For example, as the depth of the steel decreases, the probe may be lowered to track the height of the steel or slag level .
  • a vertical positioning means is well known and includes an articulated arm and an arm moving assembly.
  • an operator attaches a probe to a vertical positioning means.
  • the operator then calibrates the height of the probe above the bottom of a metallurgical vessel with readings from the positioning means.
  • the steel meniscus or depth of a slag layer in a metallurgical vessel may be determined by lowering the device into the molten steel so that the tapered end is affirmatively below the slag.
  • the electrical properties are tracked as a function of height of the probe in the vessel .
  • An analogous measurement includes a plot of electrical properties as a function of time, where time correlates with the height of the probe in the vessel or the decrease in material in the metallurgical vessel. Most commonly, the probe is slowly raised until the electrical meters register a change in slope .
  • the probe could transect several interfaces simultaneously. This situation could complicate a plot of electrical properties versus height by overlapping several curves at the same time .
  • Appropriate deconvoluting routines which are well known in the art, can separate the contributions from the various layers and determine thickness of solid and liquid slag and the depth of the molten steel. The routines are conveniently performed as part of the computer circuitry.
  • the probe may also be held stationary near a bottom aperture of a vessel. At this position, the probe will signal the proximity of the slag to the bottom of the vessel.
  • FIG. 3 Another alternative embodiment of the invention, as shown in FIG. 3, uses a plurality of vertically displaced probes, 1A, IB and 1C, to obtain simultaneous impedance readings at various heights above the bottom of the vessel 3.
  • a first probe 1A penetrates into the liquid steel 4
  • a second probe IB is in the slag
  • this embodiment permits the simultaneous determination of the menisci of steel, liquid slag and solid slag.
  • Benefits of this embodiment include a decrease in mechanical complexity by removing the vertically positionable means, innate redundancy, and the ability to determine slag depth instantly across a broad height range .

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

L'invention concerne un dispositif et un procédé servant à déterminer le ménisque et la profondeur de l'acier en fusion et du laitier dans des récipients métallurgiques. Le dispositif décrit une sonde en céramique conductrice d'électricité qui possède une extrémité distale effilée et une extrémité proximale, des compteurs de potentiel et d'impédance électrique et un conducteur électrique dont une première extrémité est fixée à l'extrémité proximale de la sonde et une deuxième extrémité est reliée aux compteurs. Le procédé consiste à étalonner la hauteur de la sonde au-dessus du fond du récipient métallurgique et à observer les changements d'impédance, révélateurs de différentes jonctions à l'intérieur du récipient. La surveillance de la jonction acier/laitier permet d'éviter la contamination par le laitier.
PCT/US1999/017566 1998-08-10 1999-08-03 Sonde effilee pour controler le niveau du moule WO2000009767A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU53336/99A AU5333699A (en) 1998-08-10 1999-08-03 Tapered probe for mold level control

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US9594698P 1998-08-10 1998-08-10
US60/095,946 1998-08-10

Publications (1)

Publication Number Publication Date
WO2000009767A1 true WO2000009767A1 (fr) 2000-02-24

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PCT/US1999/017566 WO2000009767A1 (fr) 1998-08-10 1999-08-03 Sonde effilee pour controler le niveau du moule

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AU (1) AU5333699A (fr)
WO (1) WO2000009767A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004032561B3 (de) * 2004-07-05 2006-02-09 Heraeus Electro-Nite International N.V. Behälter für Metallschmelze sowie Verwendung des Behälters
CN102393234A (zh) * 2011-11-03 2012-03-28 云南新立有色金属有限公司 一种密闭电炉高钛渣生产中渣、铁液位测量的方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4615351A (en) * 1983-07-01 1986-10-07 Norddeutsche Affinerie Ag Method of and apparatus for monitoring the surface level of material in a vessel
JPH03110387A (ja) * 1989-09-22 1991-05-10 Mazda Motor Corp 金属溶湯のレベル検知装置
US5105874A (en) * 1989-09-13 1992-04-21 Institut De Recherches De La Siderurgie Francaise (Irsid) Process for continuously determining the thickness of the liquid slag on the surface of a bath of molten metal in a metallurgical container
WO1998029743A1 (fr) * 1997-01-02 1998-07-09 Vesuvius Crucible Company Appareil et procede permettant de mesurer la profondeur de l'acier en fusion et de la scorie

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4615351A (en) * 1983-07-01 1986-10-07 Norddeutsche Affinerie Ag Method of and apparatus for monitoring the surface level of material in a vessel
US5105874A (en) * 1989-09-13 1992-04-21 Institut De Recherches De La Siderurgie Francaise (Irsid) Process for continuously determining the thickness of the liquid slag on the surface of a bath of molten metal in a metallurgical container
JPH03110387A (ja) * 1989-09-22 1991-05-10 Mazda Motor Corp 金属溶湯のレベル検知装置
WO1998029743A1 (fr) * 1997-01-02 1998-07-09 Vesuvius Crucible Company Appareil et procede permettant de mesurer la profondeur de l'acier en fusion et de la scorie

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 015, no. 303 (M - 1142) 2 August 1991 (1991-08-02) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004032561B3 (de) * 2004-07-05 2006-02-09 Heraeus Electro-Nite International N.V. Behälter für Metallschmelze sowie Verwendung des Behälters
US9829385B2 (en) 2004-07-05 2017-11-28 Heraeus Electro-Nite International N.V. Container for molten metal, use of the container and method for determining an interface
CN102393234A (zh) * 2011-11-03 2012-03-28 云南新立有色金属有限公司 一种密闭电炉高钛渣生产中渣、铁液位测量的方法

Also Published As

Publication number Publication date
AU5333699A (en) 2000-03-06

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