US2592517A - Closed electric furnace - Google Patents

Closed electric furnace Download PDF

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Publication number
US2592517A
US2592517A US189402A US18940250A US2592517A US 2592517 A US2592517 A US 2592517A US 189402 A US189402 A US 189402A US 18940250 A US18940250 A US 18940250A US 2592517 A US2592517 A US 2592517A
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US
United States
Prior art keywords
furnace
ring member
electrode
gas
roof
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US189402A
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English (en)
Inventor
Ingelsrud Arne Hildor
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Elektrokemisk AS
Original Assignee
Elektrokemisk AS
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 Elektrokemisk AS filed Critical Elektrokemisk AS
Application granted granted Critical
Publication of US2592517A publication Critical patent/US2592517A/en
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Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/30—Arrangements for extraction or collection of waste gases; Hoods therefor
    • F27D17/304—Arrangements for extraction or collection of waste gases; Hoods therefor specially adapted for electric arc furnaces
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/10—Mountings, supports, terminals or arrangements for feeding or guiding electrodes
    • H05B7/103—Mountings, supports or terminals with jaws
    • H05B7/105—Mountings, supports or terminals with jaws comprising more than two jaws equally spaced along circumference, e.g. ring holders
    • 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
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces
    • F27D11/08—Heating by electric discharge, e.g. arc discharge
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/60—Heating arrangements wherein the heating current flows through granular powdered or fluid material, e.g. for salt-bath furnace, electrolytic heating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/12—Arrangements for cooling, sealing or protecting electrodes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/18—Heating by arc discharge
    • H05B7/20—Direct heating by arc discharge, i.e. where at least one end of the arc directly acts on the material to be heated, including additional resistance heating by arc current flowing through the material to be heated

Definitions

  • This invention relates to closed electric furnaces of the type adapted for use in making calcium carbide, ferro-alloys and other products demanding high temperatures.
  • the furnace of my invention has a main body portion above which is suspended a metal roof.
  • the electrodes pass through the roof.
  • the roof will be made with a substantlally flat portion and side portions running down to meet the body of the furnace.
  • These roof members preferably are water-cooled and may be supported in any desired way. For example, they may be suspended from a superstructure associated with the furnace unit.
  • the roof must be made of separate sections electrically insulated from each other and a field with magnetic insulation should also be introduced to reduce the inductive loss or voltage as much as possible at the points where the electrodes pass through the roof. This is an added reason for making the roof in separate sections which may be exchanged individually and bolted together.
  • the roof is electrically insulated from the electrodes and preferably from the suspension mechanism and from the furnace body on which the edges of the roof ordinarily rest.
  • the present invention relates to an apparatus in which the escape of the developed gases is taken care of and at the same time the eiciency of the furnace is maintained.
  • the charge be introduced into the furnace zone at a distance from the electrode so that there is a continuous flow of material from the mouth of the charging shaft downwardly and inwardly toward the electrode.
  • the gases can readily escape through this moving surface. In such cases the gases surround the electrode but they must be withdrawn at a distance from the electrode, as it is highly inefficient to have them burned where the ignition will directly affect the electrode.
  • the clamps that suspend the electrode and carry current to it preferably go down into this ring zone and are provided with a circular jacketing member which makes a gas-tight joint with the electrode and which preferably is water-cooled.
  • This member is concentric with the electrode and its surface is such that it can be maintained quite smooth. A sliding contact can then be maintained between the surface of this member and the ring member referred to so that a relatively good gas-tight joint can be maintained between the electrode and the ring member while permitting continuous vertical movement or agitation of the electrode.
  • This ring member serves as the inner limit of the charging shafts for the .material to ce introduced into the furnace and the flow of the charge will be from this ring member toward the electrode surface so that the gas can escape directly up into the space between the electrode and the ring member.
  • the angular distance between the charging shafts should be less than and preferably not over 45. That is each space between the charging shafts should be less than one-sixth and preferably not more than one-eighth of the ring perimeter.
  • a simple construction involves the use of three segmental charging shafts and in such case the charging shafts occupy a major proportion of the peripheral space about the ring member.
  • valleys formed between the charging shafts tend to interfere with the electrical eciency of the furnace, these valleys serve to supply passages for the escape of gas from the inner ring member to the general furnace area.
  • the valleys may be big enough to permit all of the gas to escape, but inasmuch as smaller valleys are preferable, I have found that in most cases it is essential to provide separate passages for the removal of the gas from within the innerr ring member.
  • Such passages may be in the form of notches at the bottom of the ring member, opening into the ⁇ spaces between the charging shafts or they may be actual holes through the ring members above the bottom edge.
  • the gases that enter the spaces between the charging shafts may be led from them directly to points outside the furnace or they may go through these spaces into the general furnace area and then the gases may be withdrawn by appropriate passages through the roof of the furnace.
  • FIG. 3 is a viewcorresponding generally to Fig. 1 showing a modified form of construction
  • Fig. 4 is a plan view of the parts shown in Fig. 3
  • Fig. 5 is a sectional view showing one of the passages for the escape of gas in the charging material adjacent such passage
  • Fig. 6 is a development of the bottom of the inner ring member of the construction shown in Fig. showing the-relationship of the depth of valley to the angular distance between the charging shafts
  • Fig. 7 is a development of a similar ring member where three charging shafts are employed spaced approximately 60 apart and no passage is cut through the ring member for the escape of gases
  • ID is the electrode.
  • I6 ⁇ is a protecting casing surrounding the contact arrangement and is preferably water-cooled.
  • the lower end of member I8 is the pressure ring I8 whose vertical position determines the pressure between the contact members I2 and the electrode I This arrangement insures a gas-tight jointbetween member I8 and the electrode I0.
  • is a ring-like shaft for introduction of the raw materials. rlhe inner rim of this shaft is formed by the cylinder wall or" ring member 22 which is preferably water-cooled. Preferably the bottom of this ring is above the furnace wall 23 as this simplifies inspection and possible stoking.
  • 24 is a pipe connecting the furnace hoppers with the shaft.
  • 26 is a packing arrangement forming an electrically insulated packing between the inner shaft ring 22 and the protecting casing I6 surrounding the contact arrangement I2. Since casing I6 is water-cooled and has a smooth cylindrical surface, a much better sliding contact can be made against it than against the surface of the electrode.
  • the space between them is preferably kept under pressure slightly above atmospheric; for example, by returning some furnace gas to this area.
  • the numeral 28 represents the furnace roof which may be water-cooled and 30 indicates the exit pipes for the gas. Two such exit pipes are shown, one running outwardly and downward tok the side, and the other extending upwardly from the center of the furnace.
  • suspension iron for the roof which may be connected at any convenient point to the xed structure surrounding the furnace but this should be electrically insulated from such structure and the connection should allow some flexibility as indicated by the spring 34.
  • Preferably three such suspension members are provided and are connected to a magnetically insulated roof section forming a single part of the furnace roof 36.
  • the charging ring is subdivided into three segments by gas conduits as indicated at 38 which take up a minor portion of the circumferential area.
  • Each of these conduits is provided with a door 40 through which the interior of the furnace is inspected and adjusted.
  • the lid over each such door is constructed to act as an explosion valve.
  • Other explosion and inspection doors 42 are positioned at suitable places in the roof.
  • gas passages 31 are cut in the cylinder wall 22 opposite each of the gas conduits 38. It will also be noted (and this is particularly shown in Fig. 5) ⁇ that the charging material coming in to the side of each such conduit will slope toward the center of such conduit making a relatively small valley so as to keep Y the material around the electrode nearly even.
  • the area of the passages through ring 22 may be reduced in size but it is only rarely and in an extreme case that the gas passages through ring 22 can be eliminated.
  • the gas conduits 38 take the gas to the general furnace area from which it can be withdrawn through the pipes 3U.
  • Figs. 3 and 4 The structure shown in Figs. 3 and 4 is similar 32 shows a to that shown in Figs. 1 andv 2 except that here the electrode Il is provided with the clamping members I3 and the pressure ring I 9 all of which are above the furnace roof. In ⁇ this case a special closure ring 44 is provided with a separate packing ring 4E and these two together act to insulate the electrode from the furnace roof.
  • the outer ring of the charging shaft is designated as 2l and the inner ring as 23.
  • Fig. 6 I show a development of the bottom portion of the ring member 22 and it is obvious that in this case where the space between adjacent charging shafts is only about 40 and where these shafts occupy the major proportion of the area immediately around the ring member 22, the valleys formed because of the charging shafts will be small. This makes for highly efficient electrical operation but it will be seen that the valley itself will only offer a small area for the escape of gas. Accordingly the bottom of the ring is cut away as indicated at 3l to increase the size of the passage for gas iiow.
  • ring member 22a In Fig. 7 the ring member is designated as 22a and in this case again three charging shafts are shown but the space between the charging shafts is substantially equal to the peripheral area occupied by the charging shafts which means that the space between adjacent charging shafts reaches the permissible maximum of about 60.
  • the electrical efficiency is lowered somewhat but is still way above that had with previous types of furnaces. In this case the area of the valley is large enough so that there is no serious danger of building up gas pressure and it is possible to operate such a furnace without cutting separate passages through the ring member 22a for the escape of gas.
  • Fig. 8 a similar development is shown, with the ring member designated as 22h.
  • the charging shafts are shown, and again the charging shafts occupy approximately one-half of the peripheral area around the ring member but due to their increase in number, the distance between adjacent charging shafts is only about 45.
  • a separate opening for the withdrawal of gas is formed above the bottom of the ring member 22h for each space between the shafts and is designated by the numeral 44. As most of the gas will escape through these passages 44 it may, if desired, be conducted directly to the exterior of the furnace by appropriate passages not shown.
  • a furnace casing a roof for the casing above the furnace casing, a circular opening in the roof, a ring member in said opening extending down from the roof, an electrode movable within said ring of smaller diameter than the ring member, means for making a substantially gas-tight sliding connection between said electrode and said ring member so that the electrode may move in and out relative to the furnace casing while the pcripheral area within the ring member forms a gas chamber, segmental charging shafts extendingzthrough the roof with said ring member forming the 'inner boundaries thereof and with their outer boundaries inside the inner line of the furnacev casing, .and ⁇ segmental spaces between such charging shafts which are of an average width equal to not more than one-sixth ⁇ of the peripheral distance around the ring member so that the charging shafts largely surround ⁇ but are'spaced from the electrode with the result .that a charge introduced through such shafts will slope toward the electrode to surround the same with relatively shallow Valleys within
  • a structure as specified in claim l in which a water-cooled cylindrical member is clamped around the electrode to form a gas-tight joint and the sliding connection is made between such cylindrical member and the said ring.
  • said ring member carries an internal packing ring adapted to rub against the face of the movable electrode to make a substantially gas-tight sliding connection between the electrode and said ring member.
  • a structure as specified in claim l in which there are a plurality of circular openings through the roof of the ring members and electrodes for each and a central passage is provided through the roof for withdrawing gases from within the furnace structure.
  • a roof for the casing above the furnace casing having portions extending down to make a connection with the furnace casing, a circular opening in the roof, a ring member in said opening extending down from the roof, an electrode movable within said ring member of smaller diameter than the ring member, means for making a substantially gas-tight sliding connection between said electrode and said ring member so that the electrode may move in and out relative to the furnace casing while the peripheral area within the ring member forms a gas chamber, segmental charging shafts through the roof of the said ring member forming the inner boundaries thereof and with their outer boundaries inside the inner line of the furnace casing and occupying a major proportion of the peripheral space about said ring member, with spaces between such charging shafts so that the charging shafts largely surround but are spaced from the electrode, with the result that 'a charge introduced through such shafts will slope toward the electrode to surround the'same with relatively shallow valleys in the charge below the ring member, passages fori the

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
US189402A 1944-06-16 1950-10-10 Closed electric furnace Expired - Lifetime US2592517A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NO254393X 1944-06-16

Publications (1)

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US2592517A true US2592517A (en) 1952-04-08

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US189402A Expired - Lifetime US2592517A (en) 1944-06-16 1950-10-10 Closed electric furnace

Country Status (6)

Country Link
US (1) US2592517A (de)
AT (1) AT164253B (de)
CH (1) CH254393A (de)
DE (1) DE824813C (de)
ES (1) ES172689A1 (de)
GB (1) GB613949A (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671816A (en) * 1951-02-15 1954-03-09 Elektrokemisk As Cylindrical electrode holder
US2694097A (en) * 1952-06-21 1954-11-09 Elektrokemisk As Electric smelting equipment and method of using same
US2795636A (en) * 1955-06-15 1957-06-11 Ici Ltd Arc-melting furnaces
US2942044A (en) * 1958-02-27 1960-06-21 Gen Electric Electric arc furnace
US3046319A (en) * 1960-01-20 1962-07-24 Allegheny Ludlum Steel Electrode stub clamp
US3177394A (en) * 1959-07-18 1965-04-06 W C Heraens G M B H Securing device for furnace electrodes
US3457355A (en) * 1967-09-19 1969-07-22 Vitro Corp Of America Brush electrode assembly for consumable electrodes
FR2031473A1 (de) * 1969-02-17 1970-11-20 Falconbridge Nickel Mines Ltd
FR2449132A1 (fr) * 1979-02-16 1980-09-12 Falconbridge Nickel Mines Ltd Procede de fusion continue a l'arc protege d'une matiere particulaire contenant des metaux et une preponderance de constituants formant des scories
EP0102323A3 (en) * 1982-08-26 1984-09-26 Arc Technologies Systems, Ltd. Electrode assembly for arc furnaces
WO2007076914A1 (de) * 2006-01-04 2007-07-12 Sms Demag Ag Vorrichtung zum nachsetzen einer elektrode für einen metallurgischen ofen

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1019831B (de) * 1951-01-15 1957-11-21 Elektrokemisk As Verfahren zur Durchfuehrung thermischer Reduktionsprozesse in elektrischen Schmelzoefen
DE3017939C2 (de) * 1980-05-10 1983-01-27 Mannesmann AG, 4000 Düsseldorf Teilgeschlossener Elektro-Reduktionsofen

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US826742A (en) * 1903-10-13 1906-07-24 Union Carbide Corp Process of reducing metallic compounds and producing carbids.
US842099A (en) * 1904-09-21 1907-01-22 American Phosphorous Company Electric melting or reducing furnace.
US1223278A (en) * 1914-06-05 1917-04-17 Union Carbide Corp Multiple-hearth electric furnace.
US1496232A (en) * 1922-04-03 1924-06-03 Fed Phosphorus Co Stock feeding and distributing apparatus for electrical furnaces
US2286732A (en) * 1941-03-20 1942-06-16 Joseph A Hardin Electric furnace

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US826742A (en) * 1903-10-13 1906-07-24 Union Carbide Corp Process of reducing metallic compounds and producing carbids.
US842099A (en) * 1904-09-21 1907-01-22 American Phosphorous Company Electric melting or reducing furnace.
US1223278A (en) * 1914-06-05 1917-04-17 Union Carbide Corp Multiple-hearth electric furnace.
US1496232A (en) * 1922-04-03 1924-06-03 Fed Phosphorus Co Stock feeding and distributing apparatus for electrical furnaces
US2286732A (en) * 1941-03-20 1942-06-16 Joseph A Hardin Electric furnace

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2671816A (en) * 1951-02-15 1954-03-09 Elektrokemisk As Cylindrical electrode holder
US2694097A (en) * 1952-06-21 1954-11-09 Elektrokemisk As Electric smelting equipment and method of using same
US2795636A (en) * 1955-06-15 1957-06-11 Ici Ltd Arc-melting furnaces
US2942044A (en) * 1958-02-27 1960-06-21 Gen Electric Electric arc furnace
US3177394A (en) * 1959-07-18 1965-04-06 W C Heraens G M B H Securing device for furnace electrodes
US3046319A (en) * 1960-01-20 1962-07-24 Allegheny Ludlum Steel Electrode stub clamp
US3457355A (en) * 1967-09-19 1969-07-22 Vitro Corp Of America Brush electrode assembly for consumable electrodes
FR2031473A1 (de) * 1969-02-17 1970-11-20 Falconbridge Nickel Mines Ltd
FR2449132A1 (fr) * 1979-02-16 1980-09-12 Falconbridge Nickel Mines Ltd Procede de fusion continue a l'arc protege d'une matiere particulaire contenant des metaux et une preponderance de constituants formant des scories
EP0102323A3 (en) * 1982-08-26 1984-09-26 Arc Technologies Systems, Ltd. Electrode assembly for arc furnaces
WO2007076914A1 (de) * 2006-01-04 2007-07-12 Sms Demag Ag Vorrichtung zum nachsetzen einer elektrode für einen metallurgischen ofen
EA013447B1 (ru) * 2006-01-04 2010-04-30 Смс Зимаг Акциенгезелльшафт Устройство для наращивания электрода в металлургической печи

Also Published As

Publication number Publication date
ES172689A1 (es) 1946-04-01
GB613949A (en) 1948-12-07
DE824813C (de) 1951-12-13
CH254393A (de) 1948-04-30
AT164253B (de) 1949-10-25

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