US3218158A - Method of controlling the exhaust of gases from a metal refining bath - Google Patents

Method of controlling the exhaust of gases from a metal refining bath Download PDF

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Publication number
US3218158A
US3218158A US263919A US26391963A US3218158A US 3218158 A US3218158 A US 3218158A US 263919 A US263919 A US 263919A US 26391963 A US26391963 A US 26391963A US 3218158 A US3218158 A US 3218158A
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United States
Prior art keywords
hood
gas
exhaust
pressure
orifice
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Expired - Lifetime
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US263919A
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English (en)
Inventor
Dumont-Fillon Jacques
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Institut de Recherches de la Siderurgie Francaise IRSID
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Institut de Recherches de la Siderurgie Francaise IRSID
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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
    • C21C5/38—Removal of waste gases or dust
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D16/00—Control of fluid pressure
    • G05D16/20—Control of fluid pressure characterised by the use of electric means
    • G05D16/2006—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means
    • G05D16/2013—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means using throttling means as controlling means
    • G05D16/202—Control of fluid pressure characterised by the use of electric means with direct action of electric energy on controlling means using throttling means as controlling means actuated by an electric motor

Definitions

  • the present invention relates to the control of the flow of exhaust gases emanating from a metal refining bath, such as a converter in an oxygen process of steel making, and more particularly to a method wherein the exhaust gases are withdrawn through a hood slightly spaced from the converter mouth and combustion of the withdrawn gases by contamination with the surrounding air is prevented by keeping the pressure differential between the surrounding atmosphere and the exhausted gases at the base of the hood at zero whereby no air enters into the hood.
  • the exhaust system to which the control method of the present invention is applied comprises the collection of a hot fluid stream of effluent emanating into the atmosphere from a steel converter or like metal refining apparatus in a hood which is slightly spaced from the mouth of the converter whereby a space is left between the base of the hood and the converter mouth, exhausting the collected eflluent from the hood while cooling it, and so controlling the exhaust suction that the fluid pressure in the space is maintained at a value substantially identical with that of the surrounding air.
  • the balanced pressure between the atmosphere and the interior of the hood at the interspace between converter mouth and hood base prevents any air from entering and mixing with the hot fluid eflluent, thus eliminating the danger of combustion, or any effluent from diffusing into the atmosphere.
  • the exhaust suction is controlled in dependence on the fluid pressure differential at the base of the hood calculated on the basis of the following equation wherein AP, is the pressure differential at the base of the hood, AP is the fluid pressure differential measured at a higher point in the hood, A and K are empirical constants, and Q is the volume of gas flow in the hood.
  • T being a reference temperature
  • T being the efliuent temperature in the hood.
  • fluid pressure differential means the difference between the fluid pressure at a given point or level, for instance at the base of the hood, and the atmospheric pressure surrounding this point or level at a given time.
  • the fluid pressure differential AP is measured and AP, is computed as a function of AP and parameters X, Y, Z, etc. of the exhaust system operation, such as the eflluent flow, its temperature, its composition, etc.
  • AP is related to AP substantially only in dependence on the flow volume Q of the effluent passing through the hood and that the other factors, such as the temperature in the hood in particular, may often be entirely neglected. It has been found that if the Equation I is fed to a relatively simple computer, this very often suflices to obtain the desired control of the exhaust suction. In some instances, however, it may be necessary to take other factors into consideration, too, in which case a somewhat more complex computer is required to take into account, for example, the temperature of the outflowing gas. This may be measured conveniently at the exit of the hood by means of a very sensitive thermocouple.
  • a conventional exhaust suction control may be used, such as fully disclosed in the above-mentioned copending application, and a computer may be interposed between the point of measuring the pressure differential and the suction control means, the computer output actuating the control means automatically in a manner well known in the art of automation.
  • the control means receives the parameter AP, obtained by the computer from the parameter AP and thus constantly holds the exhaust suction to a value maintaining the pressure differential between the interspace separating the hood from the converter mouth and the surrounding atmosphere at zero.
  • a conventional control device may be replaced by a computer which constantly solves the equations guiding the operation of the device, including Equation I, whereby the exhaust suction force is calculated constantly as the operation proceeds and thus an absolutely flawless operation is assured by keeping the pressure differential at the base of the hood absolutely and at all times at zero.
  • FIG. 1 is a chart showing curves at different temperatures, which relate the parameters AP AP and the flow volume Q;
  • FIG. 2 is a diagrammatic view of the exhaust installation for an efiluent from a steel converter operated according to the invention.
  • FIG. 3 is a schematic view and circuit diagram of the control means in the installation of FIG. 2.
  • FIG. 1 shows curves of the pressure differential AP -AP as a function of the gas volume Q flowing through the hood, three curves for the respective gas exit temperatures of 750 (3., 850 C. and 900 C. being given. These temperatures were measured at the exit of the hood into the exhaust conduit and the exhaust system was used for conducting away and cooling the eflluent gases from a steel converter of five tons capacity and operating in an oxygen process. The pressure variations are indicated in millimeters of water and the gas flow volume in standard cubic meters per minute.
  • Equation 1 AP :AP A -KQ A2030 and K:0.0005 for 850 C.
  • AP ::AP O.300.O005Q P P and A being expressed in mm. of water and Q in standard cu. m./min,
  • Equation 11 i.e. MT -T
  • FIG. 1 indicates the constant k;:0.001.
  • Equation II reads FIG. 2 schematically illustrates an exhaust installation for conducting and cooling effluent gas safely from the steel converter 1, the efiluent fluid discharge from the converter being nomally of relatively great volume and of relatively high temperature, and containing dust, smoke, fumes, etc.
  • an eflluent exhaust hood 2 is mounted above, and vertically spaced from, the mouth of the converter, with its exit or outlet leading into exhaust conduit 3.
  • An interspace is left between the base of the hood and the converter mouth, through which air from the surroundingatmosphere could enter or efliuent could diffuse into the surrounding atmosphere it the pressure ditferential at this point were not maintained at zero so that no lateral gas flow occurs.
  • the exhaust conduit 3 leads into a dust removing humidifier 4 built as a venturi. While the eflluent is exhausted through this system, it is simultaneously cooled by jacketing the hood and the conduit and continuously flowing a cooling fluid, such as water, therethrough. The eflluent is exhausted by the suction force exerted by blower 5 whose input is connected to the humidifier 4 and whose output conducts the dust-free gas, composed primarily of carbon monoxide, to a chimney 7 where it is burned.
  • a dust removing humidifier 4 built as a venturi.
  • the exhaust suction force is controlled by butterfly or throttle valve 6 arranged in the exhaust conduit and controlling the gas flow therethrough.
  • the pressure differential AP is measured at a given level within the hood 2 by three tubes 9a, 9b, 9c connected in series to one chamber of a pressure differential indicator 8 with a flexible membrane and, at the same level, by a tube it in the surrounding atmosphere and connected to the other chamber of the indicator 8.
  • This indicator is fully described in the copending application, which forms part of the present disclosure, and includes an eletromagnetically displaceable transmitter which furnishes an electrical signal proportional to the pressure differential by means of an interposed electrical generator and demodulator ill.
  • thermocouple 12 placed at the inlet or entry of exhaust conduit 3.
  • the efiiuent volume flow is measured after the eflluent has been cooled and made dust-free by conducting the cooled and cleaned gas through venturi 13 in chimney 7, rue venturi being in communication with an electric flowmeter 14, automatically corrected for pressure, temperature and humidity.
  • This flowmeter actually is a differential manometer measuring the depression caused in venturi 13 and transmitting its reading electrically.
  • the electrical signals from generator-demodulator 11 (indicating the pressure differential AP obtained from tubes 9a, 9b, 9c and iii), from thermocouple 12 and from the electric flowmeter 1 are transmitted by the control circuit consisting of lines 41, 42 and 43 to the electronic computer l5 which correlates the pressure differential, the temperature and the eflluent flow volume to produce an AH, according to Equation II.
  • the resultant output signal indicating the actual pressure differential AP, at the base of the hood 2, where it cannot be measured, is fed to a potentiometer 16 provided with a conventional pneumatic governor 17 which controls the position of valve 6 so that the pressure differential AP, constantly remains at zero. All of this control mechanism may be entirely conventional and an illustrative embodiment thereof is fully described in the copending application mentioned hereinabove.
  • the atmospheric pressure taking tube it leads into chamber 8' of the pressure differential indicator 3 while the tubes 9a, 9b, 90, which take the efliuent pressure within the hood at the same level as tube it lead into the other indicator chamber 8", the two chambers being separated by flexible membrane or diaphragm 3a.
  • a magnetic core, 8b for instance of iron, is connected to the membrane 8a and is reciprocated between pick-up coils 80 by any pressure diflerential in indicator chambers 8', 8 causing the membrance 8a to be flexed. Reciprocation of core 812 will vary the impedance in coil 80 constituting an electromagnetic transmitter.
  • the coil 80 is fed by an oscillator 11a which delivers current at 1000 c.p.s.
  • the signal delivered by the transmitter 8c is demodulated by a conventional electronic demodulator lilb and the output voltage of the demodulator is fed to an automatic electronic potentiometer 18 provided with a calibrated filament 18a.
  • This filament delivers a voltage proportional to the measured pressure differential AP
  • the term automatic potentiometer designates an apparatus measuring a voltage or electromotive force by the method of opposielectrical resistance element provided with a runner or index continuously displaceable along the resistance ele electrical output signal indicating the pressure differential tion, an equilibrium being realized automatically by a i merit. Such a resistance is frequently called a potentiometer.
  • the gas flow volume passing through the exhaust conduit is measured in the same manner by a pressure differential pressure gage or manometer 19, forming part of flowmeter 14.
  • One conduit leads from the inlet of venturi 13 to one chamber of the gage while another conduit leads from the venturi output to the other gage chamber whereby the loss of pressure in the venturi is registered by the gage.
  • the electromagnetic transmitter 20 is fed by an oscillator 21a at 1000 c.p.s. and its output signal is demodulated by demodulator 21b, the demodulated output signal being transmitted to automatic potentiometer 22 provided with calibrated filaments 22a delivering an output voltage AP proportional to the pressure differential of venturi 13.
  • This output voltage does not represent the gas flow volume and it is, therefore, necessary to correct this as a function of the gas pressure, its temperature and its density, according to the following equation:
  • Equation III the square of the gas volume is obtained directly and may thus be placed into Formula I or II designed to obtain the parameter AP,.
  • the correction according to Equation III is effected in a servo mechanism 23 which receives signal AP from filament 22a and the correction signal Ta correlating them in a known manner by a calibrated filament 23a to whose respective ends the signals are applied, and including a zero amplifier 23b and an equilibrium motor 230 which positions the calibrated filament 23a at equilibrium.
  • a calibrated filamerit emitter 23d delivers the coefficient k an adjustable voltage being delivered to the ends of filament 23d.
  • the correction coefiicient T10 itself is obtained as the output signal from an electrical adder 24 comprising an electronic amplifier 24a which receives signal k (0), on the one hand, and signal k (CO on the other hand.
  • An adjustable resistance 24]) makes it possible to vary the proportion of the input signals k (0) and k (CO
  • Signal k (0) comes from an automatic potentiometer 25 provided with a calibrated emitter filament 25a which receives the signal from a thermocouple 26 placed in the exhaust conduit at the inlet of venturi 13.
  • the signal k (CO comes from a gas analyzer 27 which analyzes the gas contents by infrared ray absorption, the output signal of the analyzer being amplified by amplifier 28 before being delivered to resistance 24b.
  • the principal calculation according to the Equation II is effected in adder 29 comprising amplifier 29a and four adder resistances 29b, 29c, 29d and 29e of which certain ones are adjustable to enable the terms of the sum to be adjusted.
  • the temperature of the exhausted efiiuent is measured at the outlet of the hood 2 by thermocouple 12 which controls automatic potentiometer 30 provided with calibrated filament 30a.
  • the constant A (which is 0.55 at a temperature of 850 C., as calculated hereinabove) is delivered by a calibrated filament 31 with manual control, the filament being kept at a constant voltage.
  • the resistances 29b, 29c, 29d and 2% receive the output signals from resistance 31, servo mechanism 23, resistance 18a and resistance 30a, the voltages of the four resistances are combined and the adder 29 delivers an output voltage through amplifier 29a, which is proportional to AP,.
  • the pneumatic governor 17 is mounted on the mechanical axle of potentiometer 16 and this governor delivers compressed air to the exhaust suction control valve 6 through conduit 33 so as to set the valve in the desired position which keeps the automatic potentiometer 16 always at zero setting, i.e. the pressure differential AP, is kept to zero.
  • the electronic computer so controls the suction force in the exhaust conduit that there is no pressure differential between the efiiuent pass ing through the interspace between converter mouth and exhaust hood, and the surrounding atmosphere.
  • potentiometer 16 being taken by way of example.
  • a socalled reference voltage is applied to a portion of calibrated filament 16a whose ends are maintained at a known constant voltage.
  • This reference voltage is opposed to the voltage to be measured and the difference therebetween is applied to an amplifier 16b which feeds a small electric equilibrium motor 160, the latter displacing the runner of the calibrated filament 16a to seek the equilibrium.
  • the motor stands still.
  • the mechanical position of the runner of filament 16a thus constitutes a measure of the unknown voltage.
  • the motor 16c may also entrain an index in front of a scale or a pen Writing on calibrated paper.
  • the position of the runner may also be transmitted to another element, such as in the case of potentiometer 16 operating the pneumatic governor 17.
  • the above-described computer and its elements constitute only an exemplary embodiment of a control system suitable for the practice of the present invention and in no way limit the same thereto, many variations and modifications being well within the skill of the person skilled in the art, particularly after bene fiting from this teaching.
  • the entire computation and control could be effected solely by pneumatically operated devices, i.e. bell-shaped differential manometers, pneumatic adder relays, pressure-operated transformers, etc.
  • diiferent electronic systems may be used to obtain equivalent results.
  • automatic potentiometers for transmitting the parameters of the equation need not be used but the electric output signals corresponding to these parameters may be delivered directly to the electronic adder by suitable measuring devices.
  • the exemplified embodiment has been used in an experimental installation where it was desired to record a great number of parameters at different points of the control circuit but this may not be necessary in many industrial installations.
  • control signal is produced in response to a parameter AP correlated to said measured pressure difference and said measured rate of fiow by the equation wherein AP; is said difference between the pressures of said stream of gas at said orifice and of said atmosphere; AP is the ditference between the pressure of said gas within said hood at said point and the pressure of said ambient atmosphere at the level of said point; A and K are empirical constants, and Q is said measured rate of flow; and said suction is applied to said stream of gas in (B is said exhaust conduit in such a manner as to reduce AP substantially to zero.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Environmental & Geological Engineering (AREA)
  • Automation & Control Theory (AREA)
  • General Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Sampling And Sample Adjustment (AREA)
US263919A 1962-03-14 1963-03-08 Method of controlling the exhaust of gases from a metal refining bath Expired - Lifetime US3218158A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR891031A FR1325023A (fr) 1962-03-14 1962-03-14 Procédé de régulation pour captage sans combustion des gaz provenant de l'affinage pneumatique des fontes

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US (1) US3218158A (de)
AT (1) AT249716B (de)
DE (1) DE1483508B1 (de)
FR (1) FR1325023A (de)
GB (1) GB1009733A (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3332676A (en) * 1964-07-16 1967-07-25 Loire Atel Forges Regulation of the collection of gases from the oxygen refining pig iron
US3352088A (en) * 1964-08-01 1967-11-14 Beteiligungs & Patentverw Gmbh Method for drawing off converter gases
US3377057A (en) * 1963-11-01 1968-04-09 Yawata Iron & Steel Co Apparatus for recovering waste gas from oxygen top blowing converter in unburnt state
US3450867A (en) * 1966-03-14 1969-06-17 Leeds & Northrup Co Estimated tap temperature calculator for basic oxygen furnace
US3475599A (en) * 1965-03-30 1969-10-28 Leeds & Northrup Co Process measurement system for basic oxygen refining of steel
US3500029A (en) * 1967-08-17 1970-03-10 Leeds & Northrup Co Charge computer for basic oxygen furnace
US3653650A (en) * 1968-12-27 1972-04-04 Yawata Iron & Steel Co Method of controlling the exhaust gas flow volume in an oxygen top-blowing converter
US4273312A (en) * 1979-03-22 1981-06-16 Dravo Corporation Method of process off-gas control
EP3956482A1 (de) * 2019-04-15 2022-02-23 ArcelorMittal Verfahren zur steuerung der absaugung von abgasen während eines stahlherstellungsverfahrens

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR87162E (fr) * 1964-07-16 1966-06-24 Loire Atel Forges Procédé et dispositif pour la régulation du captage des gaz d'affinage à l'oxygène
US3377158A (en) * 1965-04-28 1968-04-09 Jones & Laughlin Steel Corp Converter control systems and methods
DE2239578C3 (de) * 1971-12-20 1982-07-22 Verfahrenstechnik Dr.-Ing. Kurt Baum, 4300 Essen Gassammelhaube für Konverter
FR2366366A1 (fr) * 1976-07-28 1978-04-28 Clesid Sa Dispositif de captage des gaz et des fumees provenant d'un convertisseur
CN108365820B (zh) * 2018-01-22 2019-07-26 清华大学 一种基于开路电压测量的太阳能电池表面清洁度判断方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2855292A (en) * 1953-12-28 1958-10-07 Henry J Kaiser Company Method of refining molten metal with oxygen containing gas
US2855194A (en) * 1954-07-21 1958-10-07 Brassert Oxygen Technik A G System for sealing a converter
GB872088A (en) * 1957-05-17 1961-07-05 Jean Daubersy Steel manufacture
US3154406A (en) * 1959-01-28 1964-10-27 Siderurgie Fse Inst Rech Exhaust for steel converter

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR813790A (fr) * 1935-11-22 1937-06-08 Int Suiker En Alcohol Cie Inte Procédé pour l'obtention d'alcool ou de levure, ou d'alcool et de levure, par fermentation de liquides contenant des hydrates de carbone
US3156156A (en) * 1958-09-08 1964-11-10 Renault Hydraulic lifting devices of tractors

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2855292A (en) * 1953-12-28 1958-10-07 Henry J Kaiser Company Method of refining molten metal with oxygen containing gas
US2855194A (en) * 1954-07-21 1958-10-07 Brassert Oxygen Technik A G System for sealing a converter
GB872088A (en) * 1957-05-17 1961-07-05 Jean Daubersy Steel manufacture
US3154406A (en) * 1959-01-28 1964-10-27 Siderurgie Fse Inst Rech Exhaust for steel converter

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3377057A (en) * 1963-11-01 1968-04-09 Yawata Iron & Steel Co Apparatus for recovering waste gas from oxygen top blowing converter in unburnt state
US3332676A (en) * 1964-07-16 1967-07-25 Loire Atel Forges Regulation of the collection of gases from the oxygen refining pig iron
US3352088A (en) * 1964-08-01 1967-11-14 Beteiligungs & Patentverw Gmbh Method for drawing off converter gases
US3475599A (en) * 1965-03-30 1969-10-28 Leeds & Northrup Co Process measurement system for basic oxygen refining of steel
US3450867A (en) * 1966-03-14 1969-06-17 Leeds & Northrup Co Estimated tap temperature calculator for basic oxygen furnace
US3500029A (en) * 1967-08-17 1970-03-10 Leeds & Northrup Co Charge computer for basic oxygen furnace
US3653650A (en) * 1968-12-27 1972-04-04 Yawata Iron & Steel Co Method of controlling the exhaust gas flow volume in an oxygen top-blowing converter
US4273312A (en) * 1979-03-22 1981-06-16 Dravo Corporation Method of process off-gas control
EP3956482A1 (de) * 2019-04-15 2022-02-23 ArcelorMittal Verfahren zur steuerung der absaugung von abgasen während eines stahlherstellungsverfahrens

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AT249716B (de) 1966-10-10
DE1483508B1 (de) 1970-08-06
FR1325023A (fr) 1963-04-26
GB1009733A (en) 1965-11-10

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