US3903014A - Method of and apparatus for measuring and controlling the rate of carburization of a melt - Google Patents

Method of and apparatus for measuring and controlling the rate of carburization of a melt Download PDF

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Publication number
US3903014A
US3903014A US441508A US44150874A US3903014A US 3903014 A US3903014 A US 3903014A US 441508 A US441508 A US 441508A US 44150874 A US44150874 A US 44150874A US 3903014 A US3903014 A US 3903014A
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Prior art keywords
wavelengths
melt
carbon dioxide
carbon monoxide
intensities
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Expired - Lifetime
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US441508A
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English (en)
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Jean Baumert
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Arcelor Luxembourg SA
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Arbed SA
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/72—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using flame burners
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20—Metals
    • G01N33/202—Constituents thereof
    • G01N33/2022—Non-metallic constituents
    • G01N33/2025—Gaseous constituents

Definitions

  • the intensities of the wavelengths characteristic of carbon monoxide and carbon dioxide are measured and a parameter of the refining is controlled in response to the combined intensities.
  • a single relatively broad band of the flame spectrum can be monitored, this band encompassing the wavelengths characteristic of carbon monoxide and carbon dioxide, and reference values can also be measured so as to allow mathematical elimination of error resulting from smoke or like variable obscuring action.
  • the present invention relates to a method of and an apparatus for inspecting and controlling the decarburization of a steel melt. More particularly this invention concerns the smelting of steel in an LD, LDAC, or similar type of converter.
  • the most common method of monitoring the refining operation is to continuously analyze the gases which are generated by the smelting operation, these gases comprising mainly carbon monoxide (CO) and carbon dioxide (CO the former being formed by the oxidation of the carbon in the melt and the latter being formed by the partial combustion of the so-formed carbon monoxide.
  • these gases comprising mainly carbon monoxide (CO) and carbon dioxide (CO the former being formed by the oxidation of the carbon in the melt and the latter being formed by the partial combustion of the so-formed carbon monoxide.
  • Another method uses the intensity of infrared light generated by the flames on the surface of the metal. Such an arrangement is substantially faster than the gas analysis which also requires relatively expensive analysis equipment. These flames on the top of the melt have a light intensity which can be related mathematically to the extent of decarburization of the melt. Clearly such a method is relatively rapid. Nonetheless is has the principal disadvantage that some melts generate relatively opaque gases which tend to obscure the flame and therefore give false readings. Also even within a normal run it is possible for the flame of one melt to be much more intense than the flame of another melt of relatively equivalent composition. Thus the results are often inaccurate.
  • Another object of this invention is to provide a method of and an apparatus for controlling decarburization of a melt.
  • a further object is the provision of a method of and an apparatus for monitoring and controlling the decarburization in a melt, which is relatively fast acting, and which gives accurate readings of the extent of carburization of the melt.
  • the frequencies corresponding to the infrared radiation given off by carbon monoxide and carbon dioxide, which are relatively close together, are picked up by a single broad-band detector.
  • the response time is almost immediate.
  • the intensity of infrared radiation of the flame at the top of the melt forms a defined mathematical relationship to the percentage of carbon remaining in the melt and therefore can be used to calculate the extent of decarburization of this melt.
  • thermal sensitive elements which generate an electrical output proportional to the amount of heat detected, since infrared radiation is detectable as heat.
  • infrared radiation having a wavelength of 2.3 microns is detected for carbon monoxide and infrared radiation having a wavelength of 2.7 microns is detected for carbon dioxide. It is of course within the scope of the present invention to sense a relatively broad range, stretching between 2 microns and 3 microns, to include both these compounds. In a case of melt generating a great deal of water vapor, it is possible to use a secondary band having a length of 4.3 microns for the CO which would otherwise be mainly obscured by the water vapor.
  • the signals derived from sensing the intensity of specific bands for the specific gases vary as a function of the temperature of the flame, which is not always in a direct proportion with the instantaneous concentrations of carbon dioxide and carbon monoxide rising from the melt. According to the present invention this deviation is eliminated or at least neutralized by providing in each measuring circuit a second filter-detector assembly which is sensitive to a different wavelength near to that part of the band of the spectrum chosen for the particular gas measuring. Since both of the intensities will vary with the temperature of the melt, it is possible to use this latter set point or reference value to cancel out the variations in the detected value of the wavelength corresponding to the composition being monitored.
  • the signal output for instance, indicating the intensity of carbon-monoxide infrared radiation is divided by the signal output of infrared radiation having a frequency relatively close to that of the carbon monoxide infrared radiation.
  • FIGS. 1 and 2 are schematic diagrams illustrating the method according to the present invention.
  • FIG. 3 is a largely diagrammatic view illustrating a control system according to this invention.
  • the control circuit shown in FIG. 1 comprises four cut-on infrared filters 10, I5, 20, and 25 each arranged next to a respective infrared cut-off filter l, and
  • the filters l0 and 10' allow infrared light having a wavelength of 2.3 microns to pass and the filters 20 and 20' allow infrared light of a wavelength of 2.7 microns to pass, corresponding to AA, and AA respectively.
  • the filters l5 and 15 allowa wavelength AM to pass which is slightly above 2.3 microns and the filters 25 and 25 allow a wavelength AM slightly above 2.7 microns to pass.
  • These filters are of the interference type, although it is equally within the scope of this invention to use absorbing filters.
  • the light passing through these sets of filters then falls on respective photocells ll, 16, 21, and 26 where it is transformed into signals indicated at U U U and U
  • the signal U is divided by the signal U in a divider I2 and the signal U is divided by signal U and another divider 22.
  • the quotients of these operations are combined in an adder 13. Since the light as frequencies Altand AA, will vary according to smoke conditions and temperature much as the light at 2.3 microns and 2.7 microns corresponding to that infrared radiation emitted by hot carbon monoxide and carbon dioxide, the quotients will be independent of any interference caused by such smoke, vapor, or the like.
  • Another divider 14 serves to calculate the latest change of the two quotients added together in adder 13, so as to give a reading proportional to the decarburization rate.
  • FIG. 2 The arrangement shown in FIG. 2 is similar to that of FIG. 1 except that a relatively broad-band filter 27 is used formed of a first infrared filter 28 which only allows infrared radiation having a wavelenth greater than 2 microns to pass and a filter 28 only allowing infrared radiation having a wavelength less than 3 microns to pass.
  • Light at a wavelength of AM is thus passed through this pair 27 of filters and is received by a photocell 29 which generates an output U which is fed into a calculator 30 into which various other outputs, corresponding to such variables as the input rate of oxygen and the like.
  • the output of this computer is fed as shown in FIG.
  • a method of controlling the decarburization of a steel melt during the refining thereof while a refining flame appears over the surface of the melt comprising the steps of:
  • wavelengths are filtered from said spectrum which lie without a band including the wavelengths characteristic of carbon monoxide and carbon dioxide.
  • wavelengths are filtered from said spectrum which are different from the wavelengths of 2.3 microns, corresponding to carbon monoxide, and 2.7 microns, corresponding to carbon dioxide.
  • said filter means includes a CO filter passing infrared radiation of a wavelength of 2.3 microns and a C0 filter passing infrared radiation of a wavelength of 2.7 microns.
  • the apparatus defined in claim 6, further comprising means for monitoring said infrared spectrum and filtering therefrom wavelengths near those characteris tic of carbon monoxide and carbon dioxide and generating an output representing the intensities of the infrared radiation at the neighboring wavelengths, and means for comparing each of the intensities characteristic of carbon monoxide and of carbon dioxide with a respective one of the intensities of said neighboring wavelengths.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
US441508A 1973-02-12 1974-02-11 Method of and apparatus for measuring and controlling the rate of carburization of a melt Expired - Lifetime US3903014A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
LU67003 1973-02-12

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US3903014A true US3903014A (en) 1975-09-02

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JP (1) JPS5710164B2 (de)
LU (1) LU67003A1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0215483A3 (en) * 1985-09-20 1987-05-27 Nippon Steel Corporation Method of spectroscopically determining the composition of molten iron
US20030136910A1 (en) * 2002-01-15 2003-07-24 Infrared Integrated Systems Ltd. Dual function sensor system
US8551209B2 (en) 2010-10-13 2013-10-08 Unisearch Associates Inc. Method and apparatus for improved process control and real-time determination of carbon content during vacuum degassing of molten metals
DE102021004593A1 (de) 2021-09-10 2023-03-16 Promecon Process Measurement Control Gmbh Metallurgischer Schmelzofen sowie Verfahren zur Bestimmung der Menge an heteromolekularem Gas

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4542408A (en) * 1983-08-31 1985-09-17 Rca Corporation Digital deghosting system
US5603746A (en) 1995-10-31 1997-02-18 Bethlehem Steel Corporation Method and apparatus to determine and control the carbon content of steel in a BOF vessel
EP3620542B1 (de) * 2017-06-30 2022-01-05 JFE Steel Corporation Verfahren zur umrichterbetriebsüberwachung und umrichterbetriebsverfahren

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3539804A (en) * 1968-12-23 1970-11-10 Us Army Fluid analysis by infrared absorption
US3735127A (en) * 1971-09-15 1973-05-22 Barnes Eng Co Infrared two gas analyzer
US3831030A (en) * 1971-07-19 1974-08-20 Texas Instruments Inc Laser-operated system for spectroscopic analysis

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3539804A (en) * 1968-12-23 1970-11-10 Us Army Fluid analysis by infrared absorption
US3831030A (en) * 1971-07-19 1974-08-20 Texas Instruments Inc Laser-operated system for spectroscopic analysis
US3735127A (en) * 1971-09-15 1973-05-22 Barnes Eng Co Infrared two gas analyzer

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0215483A3 (en) * 1985-09-20 1987-05-27 Nippon Steel Corporation Method of spectroscopically determining the composition of molten iron
AU581785B2 (en) * 1985-09-20 1989-03-02 Nippon Steel Corporation Method of spectroscopically determining the composition of molten iron
US20030136910A1 (en) * 2002-01-15 2003-07-24 Infrared Integrated Systems Ltd. Dual function sensor system
US8551209B2 (en) 2010-10-13 2013-10-08 Unisearch Associates Inc. Method and apparatus for improved process control and real-time determination of carbon content during vacuum degassing of molten metals
DE102021004593A1 (de) 2021-09-10 2023-03-16 Promecon Process Measurement Control Gmbh Metallurgischer Schmelzofen sowie Verfahren zur Bestimmung der Menge an heteromolekularem Gas
WO2023036352A1 (de) 2021-09-10 2023-03-16 Promecon Process Measurement Control Gmbh Metallurgischer schmelzofen sowie verfahren zur bestimmung der menge an heteromolekularem gas

Also Published As

Publication number Publication date
JPS5710164B2 (de) 1982-02-25
LU67003A1 (de) 1974-03-07
JPS49113713A (de) 1974-10-30

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