US3812364A - Method and arrangement for determining the c-content in chemical processes - Google Patents

Method and arrangement for determining the c-content in chemical processes Download PDF

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US3812364A
US3812364A US00076997A US7699770A US3812364A US 3812364 A US3812364 A US 3812364A US 00076997 A US00076997 A US 00076997A US 7699770 A US7699770 A US 7699770A US 3812364 A US3812364 A US 3812364A
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activation
periods
milliseconds
period
neutrons
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K Rumpold
F Viehbock
M Higatsberger
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
    • G01N23/221—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by activation analysis
    • G01N23/222—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by activation analysis using neutron activation analysis [NAA]

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  • FIGZ SUMMARY OF THE INVENTION The present invention relates to a method of, and apparatus for, determining the carbon content of a material undergoing chemical processing and, more particularly, for determining the carbon content in the production of steel.
  • a continuous analysis of the melt is especially desirable in the automatic processes of an LD steel mill.
  • samples were drawn chiefly from the melts and routinely analyzed by a variety of methods with different measuring times and with different degrees of accuracy.
  • a serious drawback of these methods is the time lag: it takes about five minutes to withdraw a sample and to perform the various analyses. It has therefore not been possible in the past to follow the process dynamically and to control it by immediate feedback.
  • Another object is to provide an analytical method of and apparatus for, the determination of the carbon content or iron in the liquid state.
  • a further object is to determine the carbon content rapidly and on a continuing basis for immediate feedback in an automatic processing system.
  • Still another object is to eliminate from the (my) analysis of the material interfering radiation due to the neutron generator.
  • intermittent bombardment by neutrons is attained by alternatingly switching the neutron generator between an ON and an Off" position.
  • the period during which the generator is in either position corresponds to the approximate half-life of 13'.
  • FIG. 1 is a diagram showing the dependence of the bombardment products B and N on the lengths of the ON and OFF times of a neutron generator;
  • FIG. 2 is a diagram showing the number of B decompositions as a function of the ratio between the carbon pulses and the oxygen pulses;
  • FIG. 3 is a schematic representation of one embodiment of the invention.
  • FIG. 4 is a schematic representation of another embodiment of the invention.
  • FIG. 1 DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • FIG. 1 represents data which were obtained when 5 X l n/cm /sec were directed onto kg of Fe (which includes about 50 g C).
  • the iron was in the form of a disk which had a diameter of 16 cm and a thickness of 3 cm, (corresponding to the half-value of the range of 4.43 Mev gamma radiation). It is evident, from FIG.
  • Sensible On and Off times for the generator are seen to lie in the range between I 100 milliseconds, and the operation of a pulsating neutron generator bears upon the number of the resulting B and N atoms exactly as shown by the curves of FIG. ll.
  • the On time of the neutron generator is too long, (corresponding to a limit value for the curve in FIG. 1), the production of gamma-emitting B atoms is no longer profitable; moreover, during the prolonged On" period, too many N and heavier nuclei will be produced.
  • the On time of the generator is too short, the production of B atoms and consequently the carbon count will be too low.
  • the Off time of the generator is too long, the count at the end of the suspended activation will be too low since the decay curve is an exponential function, as is well known. But if the Off time is too short the count will also be too low because in relation to the Off" time the On" time will predominate. Since the gamma radiation is measured only during the Off time, the measuring time per unit time becomes too short and hence, the intensity will be found to be too low.
  • FIG. 2 The optimal On and Off times for a neutron generator are shown in FIG. 2, where the B emission, as a function of the ratio of the carbon pulses to the oxygen pulses is plotted against various values of On" and Off times. It was found that the coordinate point in FIG. 2 remains constant if On and Off" times are reversed. FIG. 2 also shows that the most appropriate On and Off times are, respectively, 20, 10, 5, or 0.1 milliseconds the values of the upper envelope of the family of curves of the figure. The yield is then about 6 X 10 pulses per minute or an average of 'IO pulses/sec of carbon alone over the entire solid angle.
  • FIG. 3 shows a crucible 1 containing a steel melt 2 whose carbon content is to be determined.
  • a neutron collimator 3 spaced from the crucible 1 includes a tritium target 4 which is disposed at the apex of an angle formed by a pair of bores 5 and 7 which communicate with one another in the interior of the collimator.
  • the target 4 is positioned in the interior of the bores 5, 7 at their junction.
  • Bore 5 communicates at its end opposite the junction with bore 7, with a linear accelerator positioned outside the crucible l.
  • Bore 7 defines a passage between the collimator 3 and the melt 2.
  • the gamma radiation 9 which is produced by the reaction C (n,p)B and the subsequent B decay is intercepted by a detector 10 which is advantageously a semi-conductor or a scintillator detector.
  • a detector 10 which is advantageously a semi-conductor or a scintillator detector.
  • the collimator 3 is preferably a spherical tank with a diameter of about 153 cm which is filled with water.
  • a stream of deuterium of about 2mA is issued from the linear accelerator 6 and passed through a tube 14 of about 8 cm diameter onto the tritium target 4
  • a neutron flux of about 10 n/sec with an energy of 14 Mev is emitted in accordance with the reaction l-I(d,n)He.
  • the flux is emitted isotropically over the entire solid angle.
  • Those neutrons 8 which pass through bore 7 arrive in the melt 2 without loss of the 14 Mev energy.
  • the other neutrons resulting from the reaction are slowed down in the water of the collimator 3.
  • the spherical collimator 3 further includes a recess (not designated) which forms a radiation shield for the oxygen lance 11 through which oxygen can be injected into the melt 2.
  • the radiation level is only 0.2 percent of the value which, according to international radiation protection standards is admissible as a perfectly harmless yet maximum longterm dose.
  • the tritium target 4 and the detector 10 are immersed in the melt 2.
  • the detector 10 is protected from the target 4 by shielding 13 which may include Li, H O, paraffin or graphite.
  • the target 4 as well as the detector 13 are disposed in a tubular pipe 12.
  • At its end distal from the melt 2 pipe 12 is connected to the linear accelerator 6 outside the crucible 1.
  • the arrangement according to FIG. 4 is advantageous because of the satisfacof oxygen into the melt through the oxygen lance. If a measurement of the gamma radiation is required instead of process control, an appropriate measuring instrument, e.g., a multichannel pulse analyzer must be inserted in the electronic circuit. From the measured gamma radiation the carbon content of the material can be deduced by simple calculation.
  • a method of determining the carbon content of material used in the production of steel comprising the steps of activating said material by bombardment with neutrons of predetermined energy in the range of about 12 to about 25 Mev; interspersing periods of predetermined length in the range of about 0.1 to about milliseconds during which said material is activated with periods of predetermined length during which activation of said material is suspended; measuring during said period of suspended activation the gamma radiation resulting from said activation of said material as the result of a C (n,p)B reaction; and deducing the carbon content of said material from said measured gamma radiation.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Analysing Materials By The Use Of Radiation (AREA)
US00076997A 1969-10-02 1970-09-30 Method and arrangement for determining the c-content in chemical processes Expired - Lifetime US3812364A (en)

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Application Number Priority Date Filing Date Title
US00139230A US3805079A (en) 1970-09-30 1971-03-19 Apparatus for determining the carbon content of a ferrous material during steel making

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT931469A AT295198B (de) 1969-10-02 1969-10-02 Verfahren und Einrichtung zur Bestimmung des C-Gehaltes bei chemischen Prozessen

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US (1) US3812364A (enExample)
AT (1) AT295198B (enExample)
DE (1) DE2044373A1 (enExample)
FR (1) FR2064898A5 (enExample)
GB (1) GB1305573A (enExample)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975643A (en) * 1974-01-23 1976-08-17 Westinghouse Air Brake Company Fail-safe opto-electronic phase inverting circuits
US4724118A (en) * 1985-10-02 1988-02-09 Commissariat A L'energie Atomique Device for detecting fissionable material
US4882121A (en) * 1985-10-18 1989-11-21 Commisseriat a l'Energie Atomique Apparatus for the detection of E. G. explosive substances
US5080856A (en) * 1989-01-13 1992-01-14 Commissariat A L'energie Atomique Apparatus for the detection of substances and in particular explosives by neutron irradiation thereof
US5373538A (en) * 1989-10-03 1994-12-13 Commissariate A L'energie Atomique System for the detection of substances and in particular explosives by the neutron irradiation thereof
US5712885A (en) * 1994-06-09 1998-01-27 Commonwealth Scientific And Industrial Research Organisation Determination of pre-reduction degree in iron ore materials
US5781602A (en) * 1996-05-17 1998-07-14 Westinghouse Electric Corporation PGNAA system for non-invasively inspecting RPV weld metal in situ, to determine the presence and amount of trace embrittlement-enhancing element
US6388260B1 (en) * 2000-03-06 2002-05-14 Sandia Corporation Solid state neutron detector and method for use
US20050195931A1 (en) * 1998-02-18 2005-09-08 Maglich Bogdan C. Binocular method and apparatus for stoichiometric analysis and imaging using subatomic particle activation
US20050254614A1 (en) * 2004-03-11 2005-11-17 Mckinny Kevin S Method and apparatus for measuring wall thickness of a vessel

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975643A (en) * 1974-01-23 1976-08-17 Westinghouse Air Brake Company Fail-safe opto-electronic phase inverting circuits
US4724118A (en) * 1985-10-02 1988-02-09 Commissariat A L'energie Atomique Device for detecting fissionable material
US4882121A (en) * 1985-10-18 1989-11-21 Commisseriat a l'Energie Atomique Apparatus for the detection of E. G. explosive substances
US5080856A (en) * 1989-01-13 1992-01-14 Commissariat A L'energie Atomique Apparatus for the detection of substances and in particular explosives by neutron irradiation thereof
US5373538A (en) * 1989-10-03 1994-12-13 Commissariate A L'energie Atomique System for the detection of substances and in particular explosives by the neutron irradiation thereof
US5712885A (en) * 1994-06-09 1998-01-27 Commonwealth Scientific And Industrial Research Organisation Determination of pre-reduction degree in iron ore materials
US5781602A (en) * 1996-05-17 1998-07-14 Westinghouse Electric Corporation PGNAA system for non-invasively inspecting RPV weld metal in situ, to determine the presence and amount of trace embrittlement-enhancing element
US20050195931A1 (en) * 1998-02-18 2005-09-08 Maglich Bogdan C. Binocular method and apparatus for stoichiometric analysis and imaging using subatomic particle activation
US20060227920A1 (en) * 1998-02-18 2006-10-12 Maglich Bogdan C Hybrid stoichiometric analysis and imaging using non-thermal and thermal neutrons
US6388260B1 (en) * 2000-03-06 2002-05-14 Sandia Corporation Solid state neutron detector and method for use
US20050254614A1 (en) * 2004-03-11 2005-11-17 Mckinny Kevin S Method and apparatus for measuring wall thickness of a vessel

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Publication number Publication date
AT295198B (de) 1971-12-27
FR2064898A5 (enExample) 1971-07-23
DE2044373A1 (de) 1971-04-15
GB1305573A (enExample) 1973-02-07

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