WO1991015727A1 - Procede et appareil de controle de l'approvisionnement en matiere premiere d'un four de fusion electrique - Google Patents

Procede et appareil de controle de l'approvisionnement en matiere premiere d'un four de fusion electrique Download PDF

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Publication number
WO1991015727A1
WO1991015727A1 PCT/FI1991/000106 FI9100106W WO9115727A1 WO 1991015727 A1 WO1991015727 A1 WO 1991015727A1 FI 9100106 W FI9100106 W FI 9100106W WO 9115727 A1 WO9115727 A1 WO 9115727A1
Authority
WO
WIPO (PCT)
Prior art keywords
raw material
supply
furnace
temperature
supply means
Prior art date
Application number
PCT/FI1991/000106
Other languages
English (en)
Inventor
Peter Arnold Henrik Solin
Pertti Kalevi Hjerppe
Carl-Gustav NYGÅRDAS
Original Assignee
Paroc Oy Ab
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 Paroc Oy Ab filed Critical Paroc Oy Ab
Publication of WO1991015727A1 publication Critical patent/WO1991015727A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
    • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
    • F27B3/18—Arrangements of devices for charging
    • F27B3/183—Charging of arc furnaces vertically through the roof, e.g. in three points
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D2003/0001—Positioning the charge
    • F27D2003/0006—Particulate materials
    • F27D2003/0007—Circular distribution
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0006—Monitoring the characteristics (composition, quantities, temperature, pressure) of at least one of the gases of the kiln atmosphere and using it as a controlling value
    • F27D2019/0018—Monitoring the temperature of the atmosphere of the kiln
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0028—Regulation
    • F27D2019/0075—Regulation of the charge quantity

Definitions

  • the present invention relates to a method for controlling the raw material supply to an electrical melting furnace over a plurality of supply means for the raw material.
  • the invention relates also to an apparatus for controlling the said raw material supply to an electrical melting furnace provided with electrodes extending into the melt from above, a plurality of supply means for the raw material, as well as means for sensing the temperature in the furnace.
  • the space above the melt surface in an electrical furnace of the said kind should be maintained as free as possible from oxygen, as the electrodes, which preferably are of graphite, ignite very easily due to the high temperature in the furnace, when oxygen is present. It can also be advantageous, depending on the type of lining in the furnace, that the oxygen content in the furnace is low. It is thus of advantage to use, in a known manner, a slight overpressure in the furnace above the melt by means of a suitable inert gas.
  • a melting furnace for continuous operation naturally requires that the raw material supply takes place substan ⁇ tially continuously so that the quantity of melt withdrawn corresponds to the quantity of raw material introduced.
  • the raw material introduced forms a layer of solid material on the surface of the melt, wherefrom it gradually melts.
  • the solid material on the surface forms a heat insulating layer, which promotes the protection of especially the inner roof and the supply means of the furnace from excess heat stresses. It is therefore desirable that the introdu ⁇ ced raw material is distributed relatively evenly over the whole melt surface, and does not form local heaps of raw material thereon.
  • the melting process does not, however, take place in the furnace evenly over the whole surface, but the material has a tendency to melt faster in the areas around the electro ⁇ des. This in turn leads to the fact that the heat ra ⁇ diation around the electrodes is greater than from other surface areas, which in turn leads on the one hand to uneconomical heat losses and on the other hand to excess stress, especially on the roof of the furnace and the lower parts of the supply tubes. In addition, these free local melt surfaces result in an uneven temperature in the melt and consequently in temperature variations in the melt which is withdrawn through the melt opening.
  • the method according to the invention is characterized in that the temperature is sensed at a plurality of areas above the melt surface in the furnace, whereby at every sensing area a deviation of the temperatu ⁇ re from a set value or from a temperature value sensed at another sensing area, is used to regulate the quantity of raw material which is fed to the furnace over that or those supply means which supply the said sensing area.
  • the method according to the invention makes it possible to divide or proportion the quantity of raw material over the different supply means in relation to the temperatures sensed by the sensing means.
  • the temperature deviation for the different sensing areas is determined either in relation to a "normal value" esta ⁇ blished for the process conditions in question, or then the temperature deviations between the different sensing areas are established.
  • the quantities or proportions of raw material supplied by the different supply means are regulated in relation to the values obtained.
  • the greatest raw material quantity is fed through that supply tube which is situated in the area where the highest temperature is measured, etc.
  • a control device for the control of the raw material supply it is appro ⁇ priate to use a control device, in which the temperature differences are established and which produces signals in response to the differences. These are in turn used for regulating the raw material supply by actuating in a suitable manner e.g. conventional valve means in the supply devices, raw material conveyors etc. It is thereby possible and easier from a process technical viewpoint to introduce raw material to the furnace over one supply means at a time, whereby the total amount of raw material to be introduced per time unit is divided over the separate supply means in accordance with the temperature differences measured for these by the sensing means.
  • the raw material supply to the furnace takes place simultaneously over a plurality of supply means in proportions which correspond to the temperature differences measured for the said supply means by the sensing means.
  • the sensing means can be of any known type provided that they withstand the high furnace temperatures.
  • the use of sensing means in melting furnaces is in itself known (e.g. NO 150 460).
  • the quantity of raw material introduced per time unit should correspond to the quantity of melt withdrawn. This can be monitored in different ways, e.g. by continuously or intermittently measuring the weight of the furnace. According to the invention the quantity of raw material which is to be introduced into the furnace is divided between the separate supply means in a manner which results in optimal conditions in the furnace with regard to heat losses from the surface and heat stresses on linings and cover.
  • the invention concerns also an apparatus for carrying out the above defined method.
  • the apparatus is characterized in that each supply means over a control unit is connected with at least one temperature sensing means for an asso ⁇ ciated area and arranged above the melt, that the control unit comprises means for comparing a temperature sensed by one or more means with a temperature value set for the process conditions in question, or with a temperature sensed by one or more other sensing means, that the apparatus comprises means for regulating the raw material supply to the supply means based on the temperature differences established by the control device.
  • the electrodes are preferably arranged symmetrically substantially along the periphery of a circle but also other possibilities exist. It is of importance that the electrodes are so arranged that as even as possible heating of the melt is obtained.
  • the supply means which preferably are supply tubes, should be arranged so as to result in as good a coverage of the melt surface as possible. This is suitably achieved so that rotating supply tubes provided with suitable spreading means are placed between the electrodes substantially along the said circle periphery and in the center of the furnace, which thus can cover large areas of the melt with raw material. Further it is of advantage to place directional supply tubes between the electrodes and the furnace wall in order to direct the raw material towards the electrodes where the melting of the raw material is most intensive.
  • the raw material should be supplied to the furnace so as not to mechanically wear on the furnace surfaces or the electrodes.
  • the end of the tube can be designed in a suitable manner, e.g. it can be bevelled or bent and/or provided with a shield against radiation from the melting raw material and made of a suitable heat resistant material, e.g. a heat resistant ceramic material (e.g. a Al 2 0 3 -based material). It is also possible, by a suitable design of the tube end, e.g. by providing a tube end bent to an arc/angle with suitably designed extensions or "fingers", to obtain a relatively even distribution of raw material over the whole area of influence of the supply tube and not only along a circular line on the surface of the melt.
  • a suitable design of the tube end e.g. by providing a tube end bent to an arc/angle with suitably designed extensions or "fingers", to obtain a relatively even distribution of raw material over the whole area of influence of the supply tube and not only along a circular line on the surface of the melt.
  • Fig. 1 shows a cross-section through a melting furnace included in the apparatus according to the invention
  • Fig. 2 shows the rotating supply means in more detail.
  • the melting furnace as a whole is designated with the reference numeral 1, and it contains a mineral melt 2 with a layer 3 of unmelted raw material.
  • a mineral melt 2 with a layer 3 of unmelted raw material.
  • the number of electrodes 4 and supply tubes 5 can naturally be arbitrary.
  • the end 6 of the supply tube 5 is bevelled in order to obtain a spreading of the raw material when the tube 5 rotates around its longitudinal axis.
  • the tubes 5 further comprise means 7, e.g. suitable valve means, for the raw material which are activated by a control signal produced by a control device P.
  • the furnace 1 is provided with temperature sensing means 8 arranged in the furnace cover, preferably heat resistant thermocouples, which extend to some degree into the furnace space.
  • every supply tube has a corresponding sensing means.
  • the sensing means produce a signal corres ⁇ ponding to the temperature at the sensing point to the control device P, which can be e.g. a processor.
  • the control device P compares the temperatures sensed by the different sensing means 8 with each other or with a temperature value set for the process conditions in question, and provides signals corresponding to the established differences for regulating the raw material supply to the associated supply tube.
  • the temperature sensing means 8 can to their number be greater or smaller than the supply tubes 5, whereby a direct association between a specific supply tube and a temperature sensing means need not exist.
  • valve means 7 not shown in detail.
  • These can be activated to feed any quantity of raw material of the total amount to be supplied over a certain time period.
  • one tube at a time is activa ⁇ ted in an order and in a quantity corresponding to the greatest temperature differences, but it is also possible to activate several tubes simultaneously and to supply through these quantities of raw material corresponding to the sensed temperature differences.
  • the regula ⁇ tion takes place by increasing the raw material supply in that or those tubes which supply raw material to that or those areas where there is a temperature increase and by decreasing the same correspondingly in the other tubes.
  • the rotating supply tubes 5 shown in the Fig. 2 comprise finger-like spreading means 9 which are advantageous in view of obtaining an even spreading of the raw material over the whole area of influence of the supply tube. It is also possible to provide the lower ends of the supply means with shielding elements 10 of a heat resistant material, preferably a ceramic material.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)

Abstract

Procédé et appareil de contrôle de l'approvisionnement en matière première d'un four de fusion électrique exploité en continu. L'appareil comporte des électrodes (4) allant de la zone située au dessus de la matière en fusion jusque dans la matière en fusion, une pluralité de dispositifs d'approvisionnement (5) pour la matière première, ainsi que des dispositifs (8) permettant de mesurer la température dans une pluralité de zones se trouvant au-dessus de la surface de la matière en fusion dans le four de fusion. L'approvisionnement en matière première est régulé sur la base des mesures de température de façon qu'une couche de matière première non fondue pratiquement toujours égale recouvre la matière en fusion.
PCT/FI1991/000106 1990-04-11 1991-04-10 Procede et appareil de controle de l'approvisionnement en matiere premiere d'un four de fusion electrique WO1991015727A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI901843 1990-04-11
FI901843A FI85912C (sv) 1990-04-11 1990-04-11 Förfarande och anordning för styrning av råmaterialtillförseln till en elektrisk smältugn

Publications (1)

Publication Number Publication Date
WO1991015727A1 true WO1991015727A1 (fr) 1991-10-17

Family

ID=8530255

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1991/000106 WO1991015727A1 (fr) 1990-04-11 1991-04-10 Procede et appareil de controle de l'approvisionnement en matiere premiere d'un four de fusion electrique

Country Status (3)

Country Link
AU (1) AU7566591A (fr)
FI (1) FI85912C (fr)
WO (1) WO1991015727A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU664805B2 (en) * 1993-04-15 1995-11-30 Ishikawajima-Harima Jukogyo Kabushiki Kaisha DC arc furnace
AU664950B2 (en) * 1993-04-15 1995-12-07 Ishikawajima-Harima Jukogyo Kabushiki Kaisha Apparatus for preheating and supplying scraps
AU668821B2 (en) * 1993-09-30 1996-05-16 Ishikawajima-Harima Jukogyo Kabushiki Kaisha Electric arc fusion furnace
GB2298834A (en) * 1995-03-16 1996-09-18 Rover Group Vehicle suspension system
GB2472462A (en) * 2009-08-07 2011-02-09 Lama D D Dekani Ingot feeding apparatus for a diecasting machine
CN102901368A (zh) * 2012-09-03 2013-01-30 连云港金蔷薇化工有限公司 一种窑炉的控制装置以及方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE166168C1 (fr) *
US1338881A (en) * 1920-02-13 1920-05-04 Stock Guy James Production of iron in an electric furnace
US3909242A (en) * 1972-10-09 1975-09-30 Elkem Spigerverket As Method for determining operating conditions in electrical furnaces
US4435815A (en) * 1981-04-27 1984-03-06 Elkem A/S Method and apparatus for charging a furnace
US4697274A (en) * 1984-09-18 1987-09-29 Voest-Alpine Aktiengesellschaft Electric melting furnace arrangement as well as a method of influencing the composition of a mineral melt for producing wool

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE166168C1 (fr) *
US1338881A (en) * 1920-02-13 1920-05-04 Stock Guy James Production of iron in an electric furnace
US3909242A (en) * 1972-10-09 1975-09-30 Elkem Spigerverket As Method for determining operating conditions in electrical furnaces
US4435815A (en) * 1981-04-27 1984-03-06 Elkem A/S Method and apparatus for charging a furnace
US4697274A (en) * 1984-09-18 1987-09-29 Voest-Alpine Aktiengesellschaft Electric melting furnace arrangement as well as a method of influencing the composition of a mineral melt for producing wool

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DERWENT'S ABSTRACT, No. 86-149, 300/23; & SU,A,1 191 721, Publ week 8623. *
DERWENT'S ABSTRACT, No. 86-168, 485/26; & SU,A,1 195 169, Publ. week 8626. *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU664805B2 (en) * 1993-04-15 1995-11-30 Ishikawajima-Harima Jukogyo Kabushiki Kaisha DC arc furnace
AU664950B2 (en) * 1993-04-15 1995-12-07 Ishikawajima-Harima Jukogyo Kabushiki Kaisha Apparatus for preheating and supplying scraps
AU668821B2 (en) * 1993-09-30 1996-05-16 Ishikawajima-Harima Jukogyo Kabushiki Kaisha Electric arc fusion furnace
AU679653B2 (en) * 1993-09-30 1997-07-03 Ishikawajima-Harima Jukogyo Kabushiki Kaisha Electric arc melting furnance
AU686069B2 (en) * 1993-09-30 1998-01-29 Ishikawajima-Harima Jukogyo Kabushiki Kaisha Electric arc melting furnace
GB2298834A (en) * 1995-03-16 1996-09-18 Rover Group Vehicle suspension system
GB2472462A (en) * 2009-08-07 2011-02-09 Lama D D Dekani Ingot feeding apparatus for a diecasting machine
CN102901368A (zh) * 2012-09-03 2013-01-30 连云港金蔷薇化工有限公司 一种窑炉的控制装置以及方法

Also Published As

Publication number Publication date
AU7566591A (en) 1991-10-30
FI901843A0 (fi) 1990-04-11
FI901843A (fi) 1991-10-12
FI85912B (fi) 1992-02-28
FI85912C (sv) 1992-06-10

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