US3653650A - Method of controlling the exhaust gas flow volume in an oxygen top-blowing converter - Google Patents

Method of controlling the exhaust gas flow volume in an oxygen top-blowing converter Download PDF

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Publication number
US3653650A
US3653650A US886823A US3653650DA US3653650A US 3653650 A US3653650 A US 3653650A US 886823 A US886823 A US 886823A US 3653650D A US3653650D A US 3653650DA US 3653650 A US3653650 A US 3653650A
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United States
Prior art keywords
exhaust gas
converter
blowing
volume
conduit
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Expired - Lifetime
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US886823A
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English (en)
Inventor
Norito Iwao
Akira Ito
Minoru Maeda
Tadashi Kawaguchi
Nakano Nobukuni
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Yawata Iron and Steel Co Ltd
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Yawata Iron and Steel Co Ltd
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    • 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
    • C21C5/30—Regulating or controlling the blowing

Definitions

  • Kitakyushu Japan [73] Assignee: Yawata Iron & Steel Co., Ltd., Tokyo,
  • the present invention has as an object to provide a method for controlling the gas flow volume for the purpose of exactly judging the carbon value of the steel bath, while still taking into account any lag in the analysis of the gas.
  • FIGS. la-lc are schematic illustrations of various states of closure of a furnace mouth part and an exhaust gas collecting device in an oxygen top-blowing converter, FIG. la showing the parts in a perfectly sealed state, FIG. lb showing the state wherein slag or metal is deposited on the furnace mouth part and some clearance exists, and FIG. 1:: showing the state wherein a large amount of slag or metal is deposited on the furnace mouth part and the clearance is almost a maximum;
  • FIG. 2 is a graph with curves showing the relations between the blowing time and the produced gas F B and entering air F, for the states shown in FIGS. la-lc, respectively;
  • FIG. 3 is a graph with curves showing the blowing time and the variation of CO in percent (1;) in the exhaust gas with the lapse of time in FIGS. la-lc, respectively;
  • FIG. 4 is a schematic view of an exhaust gas flow volume controlling apparatus according to the present invention.
  • FIG. 5 is a diagram showing the relation between the gas flow volume based on a conventional furnace pressure controlling method and the end point molten steel carbon in percent;
  • FIG. 6 is a relative diagram representing the operation in FIG. 5 with the decarburizing velocity and end point molten steel carbon in percent;
  • FIG. 7 is a diagram showing the relations between the gas flow volume based on the operating method of the present invention and the end point molten steel carbon in percent.
  • FIG. 8 is a diagram showing the relations between the decarburizing velocity and the end point molten steel carbon in percent when the exhaust gas information based on the operating method of the present invention is utilized.
  • the exhaust gas When recovering CO-containing exhaust gas, it is, of course, necessary to elevate the CO content by preventing the outside air from entering into the exhaust gas as far as possible.
  • the exhaust gas when utilizing'the exhaust gas as a source of information for a steel making operation, particularly for the judging of the carbon value of a steel bath, the exhaust gas should be regarded as a primary means for detecting the state of the reaction in the furnace.
  • the variation of the actual flow volume of the exhaust gas produced by the decarburizing reaction within a converter or particularly the exhaust gas flow volume pattern in the final period of the blowing has a very close correlation with the carbon value of the steel bath. Therefore, by utilizing this fact, the carbon value of the final bath can be determined.
  • the furnace pressure control is carried out for the purpose of maintaining the quality of the recovered gas, that is, for preventing the dilution of the gas being recovered by air entering through the furnace mouth part.
  • a hood and movable skirt are provided between the furnace mouth of a converter and a gas conduit and an exhaust gas flow volume regulating device such as, for example, a damper is positioned in the gas conduit so that the pressure in the hood can be detected and the opening of said damper can be adjusted so as to give a determined pressure.
  • the skirt for intercepting the entering air must be perfectly closed. That is, in order to attain the expected object, a strict air-tightness of the furnace mouth is required. However, in fact, due to the slopping during the blowing, slag or metal is often deposited on the furnace mouth part. In most cases, it is impossible to perfectly shield the skirt. Therefore, the furnace pressure control in the strict sense of the word is no longer performed.
  • the gas flowing through the gas conduit consists of only the exhaust gas F 5 produced from the decarburizing reaction and the pressure within the furnace can be controlled to a determined one.
  • the skirt is somewhat opened on account of the deposition of slag or the like as in the case b, the outside air enters through this clearance, and the gas flowing through the gas conduit is the volume of the exhaust gas F, of the case a with the addition of the entering air as is shown in FIG. 2 and produces a determined pressure in a so-called diluted state.
  • the furnace pressure is controlled as determined.
  • the time required for recovering the exhaust gas is shorter in the cases of b and 0 than in the case of a, for a determined limit of percent of CO in the recovered exhaust gas.
  • the gas treating equipment becomes unnecessarily large on account of the increase in the total exhaust gas flow volume.
  • an analysis time lag (quantitatively usually more than l0 seconds) which is a combination of the time lag due to the movement of the gas from the furnace mouth part to the gas analyzer and the time lag in analyzing the gas, which has arrived at the analyzer, and converting'it'to an electrical signal.
  • FIG. shows relations between the exhaust gas flow volume (including entering air) and the carbon in the end point molten steel when a conventional furnace pressure control was carried out under a certain blowing condition. The fluctuation is very large therein.
  • FIG. 6 shows the relations between the decarburizing velocity and the carbon in the end point molten steel graphed on the basis of the above relations. The fluctuation is likewise very large therein.
  • the carbon value of the steel bath can be determined only by measuring the exhaust gas flow volume, if said analysis value could be set to a determined value by regulating the amount of air suckedm.
  • the present invention brings the correlation between the carbon value of the steel bath and the gas flow volume into conformity with that of the past charges, while lessening fluctuations of the exhaust gas flow volume in the final period of the blowing by regulating the amount of air sucked-in during said period.
  • the present invention is characterized by a method comprising the steps of sucking an exhaust gas produced from an oxygen top-blowing converter through an exhaust gas conduit having a suction fan, regulating a gas flow volume controlling device provided in the exhaust gas conduit so that the momentary flow volume value of the exhaust gas flowing through said exhaust gas conduit will coincide with the variation over a period of time of a dry gas flow volume in a standard state predetermined in response to blowing conditions and calculating the decarburizing velocity from said exhaust gas flow volume and the analysis value of the exhaust gas, thereby making it possible to judge the carbon value of a steel bath.
  • the present invention contemplates at the same time carrying out the recovery operation of the exhaust gas produced from an oxygen top-blowing converter smoothly by restricting the entry of the outside air, blowing the indicated volume of the outside air in the initial and final periods of blowing respectively so that it is mixed with the gas in the furnace for combustion, thereby avoiding the danger of explosion, and solving the problem of surging accompanying the reduction of the gas volume by the suction fan or omitting the step of diluting the gas with an inert gas.
  • l is a converter into which oxygen is introduced while melting pig iron.
  • a hood 2 for collecting an exhaust gas produced by oxygen blowing is mounted above the converter.
  • a vertically movable skirt 2 is arranged between the converter furnace mouth 1 and said hood 2.
  • the hood 2 is connected to an exhaust gas conduit 3 which in turn is connected to a gas flow meter 13, which is a flow volume measuring throttling mechanism, and suction fan 5 through a venturi tube 6 and dust collector 12.
  • a damper 4 to control the gas flow volume which flows through the exhaust gas conduit 3 is positioned ahead of the gas flow meter 13.
  • an ordinary PA venturi tube is used.
  • the device is not limited to the venturi but any type of device which can control the flow volume will do.
  • 7 is a damper operating cylinder operated by a regulator 8.
  • 17 is a gas analyzer
  • 18 is a flow meter
  • 19 is a calculator for integrating the measured values from the flow meter and the analyzer.
  • the volume F0 of oxygen blown into the converter is supplied into a controller 9 as a signal from a signal generating means 16. Meanwhile the momentary coefficient a(t) and combustion coefficient K (in other words, the volume of air sucked in), as will be described later, are indicated by a multiplier 10.
  • the signal representing F0 as multiplied by these coefficients is supplied to the controller 9.
  • the actual exhaust gas is measured by the flow meter 13 and a signal representative thereof is introduced into said controller 9 and an instruction to cancel the difference between them is transmitted to the regulator 8 to regulate the controlling damper 4.
  • This difference pressure is converted to a dry gas flow volume at a standard state by correcting the humidity, pressure and temperature with a corrector 13' by using signals from the pressure gauge 14 and thermometer 15.
  • the exhaust gas volume is so small that there is a danger of a gas explosion due to the surging by the suction fan and the presence of residual 0 Therefore, it is also an object of the present invention to determine a combustion coefficient K so that the exhaust gas volume will be Q a'Fo 'K so as to burn CO by sucking in a certain amount of air.
  • the total exhaust gas volume is Q 2Fo -K as described above.
  • the total exhaust gas volume Q is the sum of these amounts and therefore is That is to say, (l+2)t) is a combustion coefficient K. Needless to say that the actual oxygen feed volume is determined based on numerical values from the past charges.
  • the method of the present invention is characterized by operating an apparatus, wherein an exhaust gas produced in an oxygen top-blowing converter is sucked through an exhaust gas conduit having a suction fan, while carrying out an exhaust gas flow volume program Q a(t) Fo K established by determining a produced gas coefficient a(t) over a period of time and a combustion coefficient K for CO in the produced gas based on an oxygen feed volume F0 (or oxygen feeding velocity) determined from the past charges, by regulating gas flow volume controlling device provided in the exhaust gas conduit on the basis of said program.
  • an oxygen feed volume F0 or oxygen feeding velocity
  • FIGS. 7 and 8 Shown in FIGS. 7 and 8 are the results of carrying out the operating method of the present invention on 125 charges on the basis of various blowing conditions and the gas information was utilized for the judgment of the carbon value in the steel bath.
  • FIG. 7 has exhaust gas flow volumes l0 Nm/hr) plotted on the ordinate and carbon contents (in percent) in the end point steel plotted on the abscissa.
  • FIG. 8 has decarburizing velocities (in kg/min) plotted on the ordinate and carbon contents (in percent) in the end point 7 Further, as is evident by comparing Tables 1 and 2, when 75 the recovery limit of the valuable CO gas is equal to percent, the gas recovering time was 6 to 7 minutes in the conven tional method but was 10 minutes in the present invention and the average of the CO concentration in the recovered gas rose greatly to 67 percent in the present method from 62 percent in the conventional method. Further, the maximum exhaust gas flow volume during the entire blowing period was reduced to 60,000 Nm lhr in the present method from 76,000 Nm lhr in the conventional method. It is evident that the entering air volume" was reduced as seen from the amount of N Thus, according to the present invention, the treatment control of the exhaust gas of an oxygen top-blowing converter,
  • the carbon value of the steel bath in the final period of the blowing can be correctly judged, the recovered gas concentration can be elevated, the volume of the gas to be treated can be reduced (the equipment can be made smaller) and the amount of outside air sucked-in can be controlled in the initial and final periods of the blowing, consequently CO becomes CO and this CO can be utilized.
  • a safe operation of controlling the flow volume of an exhaust gas from an oxygen top-blowing converter can be established.
  • a method of operating an oxygen top blowing converter having an apparatus for recovering converter exhaust gas which includes a gas flow volume control means in an exhaust gas conduit, wherein molten iron is refined by continuously blowing a certain amount of oxygen into the molten iron in the converter through a lance and the carbon content of the molten steel in the converter is judged from exhaust gas information from the apparatus for recovering converter exhaust gas, which apparatus draws the exhaust gas discharged from the converter mouth into the apparatus by means of a suction blower provided in the exhaust gas conduit in the apparatus,

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
US886823A 1968-12-27 1969-12-22 Method of controlling the exhaust gas flow volume in an oxygen top-blowing converter Expired - Lifetime US3653650A (en)

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JP9601368 1968-12-27

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US (1) US3653650A (de)
AT (1) AT312022B (de)
DE (1) DE1965073C3 (de)
FR (1) FR2027240B1 (de)
GB (1) GB1296069A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3908969A (en) * 1971-12-20 1975-09-30 Pennsylvania Engineering Corp Method and apparatus for air pollution control combined with safe recovery and control of gases from a bottom-blown steel converter vessel
US20030015090A1 (en) * 2001-03-22 2003-01-23 Shore Christopher R. Closed capture emission system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1945589C2 (de) * 1969-09-09 1981-10-29 Otto Sauer Achsenfabrik Keilberg, 8751 Bessenbach Vorrichtung zum Stabilisieren von Nachlauflenkachsen von Kraftfahrzeugen
DE3616998A1 (de) * 1986-05-21 1987-11-26 Bergische Achsen Kotz Soehne Verbundachsaggregat
DE4202827A1 (de) * 1992-01-31 1993-08-05 Linde Ag Geregelter betrieb von industrieoefen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3218158A (en) * 1962-03-14 1965-11-16 Siderurgie Fse Inst Rech Method of controlling the exhaust of gases from a metal refining bath
US3329495A (en) * 1963-09-26 1967-07-04 Yawata Iron & Steel Co Process for measuring the value of carbon content of a steel bath in an oxygen top-blowing converter
US3372023A (en) * 1964-05-23 1968-03-05 Beteiligungs & Patentverw Gmbh Method of monitoring and controlling the oxygen blowing process
US3377158A (en) * 1965-04-28 1968-04-09 Jones & Laughlin Steel Corp Converter control systems and methods
US3463631A (en) * 1963-12-03 1969-08-26 Siderurgie Fse Inst Rech Method and arrangement for determining the oxidation reactions during refining of metals
US3522035A (en) * 1966-12-14 1970-07-28 Westinghouse Electric Corp Determining operation of furnace vessel

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1442772A (fr) * 1964-07-27 1966-06-17 Siemens Ag Procédé pour le contrôle ou le réglage du courant de gaz d'échappement des convertisseurs

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3218158A (en) * 1962-03-14 1965-11-16 Siderurgie Fse Inst Rech Method of controlling the exhaust of gases from a metal refining bath
US3329495A (en) * 1963-09-26 1967-07-04 Yawata Iron & Steel Co Process for measuring the value of carbon content of a steel bath in an oxygen top-blowing converter
US3463631A (en) * 1963-12-03 1969-08-26 Siderurgie Fse Inst Rech Method and arrangement for determining the oxidation reactions during refining of metals
US3372023A (en) * 1964-05-23 1968-03-05 Beteiligungs & Patentverw Gmbh Method of monitoring and controlling the oxygen blowing process
US3377158A (en) * 1965-04-28 1968-04-09 Jones & Laughlin Steel Corp Converter control systems and methods
US3522035A (en) * 1966-12-14 1970-07-28 Westinghouse Electric Corp Determining operation of furnace vessel

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3908969A (en) * 1971-12-20 1975-09-30 Pennsylvania Engineering Corp Method and apparatus for air pollution control combined with safe recovery and control of gases from a bottom-blown steel converter vessel
US20030015090A1 (en) * 2001-03-22 2003-01-23 Shore Christopher R. Closed capture emission system
US6752710B2 (en) * 2001-03-22 2004-06-22 Dana Canada Corporation Closed capture emission system

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Publication number Publication date
FR2027240B1 (de) 1973-07-13
GB1296069A (de) 1972-11-15
DE1965073B2 (de) 1978-06-01
DE1965073A1 (de) 1971-01-28
FR2027240A1 (de) 1970-09-25
AT312022B (de) 1973-12-10
DE1965073C3 (de) 1979-02-01

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