CA1155176A - Method for compensation of the reactive power of an electric smelting furnace operated with three-phase current - Google Patents
Method for compensation of the reactive power of an electric smelting furnace operated with three-phase currentInfo
- Publication number
- CA1155176A CA1155176A CA000361747A CA361747A CA1155176A CA 1155176 A CA1155176 A CA 1155176A CA 000361747 A CA000361747 A CA 000361747A CA 361747 A CA361747 A CA 361747A CA 1155176 A CA1155176 A CA 1155176A
- Authority
- CA
- Canada
- Prior art keywords
- contact
- jaws
- phase
- electrode
- compensating
- 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
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
-
- 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
- H05B3/0019—Circuit arrangements
- H05B3/0023—Circuit arrangements for heating by passing the current directly across the material to be heated
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P80/00—Climate change mitigation technologies for sector-wide applications
- Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Electrical Variables (AREA)
- Supply And Distribution Of Alternating Current (AREA)
- Furnace Details (AREA)
- General Induction Heating (AREA)
- Curtains And Furnishings For Windows Or Doors (AREA)
- Non-Portable Lighting Devices Or Systems Thereof (AREA)
- Vertical, Hearth, Or Arc Furnaces (AREA)
Abstract
ABSTRACT
A method for compensation of the reactive power of an electric smelting furnace, operated with three-phrase current, to which electrical power is supplied through a three-phrase transformer or through three single-phase transformers interconnected to a three phase system comprises the supply of electrical power through high-tension lines, contact-jaws, and electrodes, the connection of compensating capacitors to separate high-tension lines, wherein three-phase voltage potential, present at the electrode, is tapped off above the contact-jaws and is used to feed the compensating capacitors, and the flow of current from the contact-jaws to the compensating device in a direction opposite to that of the current flowing to the electrode from the furnace transformer, for the purpose of decreasing the inductance. A device is especially adapted to carry out this method.
A method for compensation of the reactive power of an electric smelting furnace, operated with three-phrase current, to which electrical power is supplied through a three-phrase transformer or through three single-phase transformers interconnected to a three phase system comprises the supply of electrical power through high-tension lines, contact-jaws, and electrodes, the connection of compensating capacitors to separate high-tension lines, wherein three-phase voltage potential, present at the electrode, is tapped off above the contact-jaws and is used to feed the compensating capacitors, and the flow of current from the contact-jaws to the compensating device in a direction opposite to that of the current flowing to the electrode from the furnace transformer, for the purpose of decreasing the inductance. A device is especially adapted to carry out this method.
Description
11~5~ 7~
Method for Compensation of the Reactive Power of an Electric Smelting Furnace . . .
Operated with Three-Phase Current The invention relates to a method for compensation of the reactive power of an electric smelting furnace, operated with three-phase current, to which electrical power is supplied through a three-phase transformer, or through three single-phase transformers interconnected to a three-phase system, through high-tension lines and contact-jaws, compensating capacitors being connected to separate high-tension lines.
Energy-conversion in the electric smelting furnace is effected, under the electrodes, as Joule's heat in the so-called hearth-resistance. As the size of the furnace increases, there is a sharp drop in ohmic resistance, due to a sharp increase in the cross-sections and volumes of current-carrying structures and electrical:Ly-active, current-carrying hearth parts, and there is a sharp increase in inductive resistance.
The result of this is that, as the size of the furnace increases, the elctrical power to be installed increases to a substantlally greater degree than the thermal power to be expected from the structural expenditure.
Efforts have therefore been made to reduce inductive resistances, e.g. by the use of bifilar conductors and/or by ~.
~5S~7s~
compensating for the reactive powers, caused by inductive resistances, by means of capacitors.
It is known to decrease inductive resistances, e.g. by using bifilar eonductors (elektrow~rme international vol~s2~
1972: Dr. Mollenkamp, Dr. Kallfelz "Modern eleetric smelting furnaces for recovering ferro-alloys, pig-iron and calcium-earbide"). However, the bifilar arrangement of the conduetors, because of the furnace circuitry, is possible only in the section of line between the furnace-transformer and the flexible part of the conductor (high-tension line) permitting movement of the electrodes. The general laws governing uncompensated three-phase eonductors (R.S.T.) apply to the remaining sections of the eurrent-eonductors, namely the high-tension line along the electrode phase-conductor, through which current is passed to the eleetrodes by means of eontaet-jaws, and to the eurrent-carrying eleetrode part thereunder. The latter seetions of the high-tension conductor system aeeount for about 70~ of the total furnaee reaetive power.
It is therefore the pupose of the invention to reduee the total reaetive power of an eleetrie smelting furnaee of the type mentioned at the beginning hereof and, more partieularly, to relieve several eomponents, used to supply power, of reaetive power. The deviee for the exeeution of the method aeeording to the invention is to be of simple design. Aeeording to the invention, this purpose is aehieved by the features set forth in the eharaeterizing portion of elaim 1. The sub-elaims eontain advantageous designs of the deviee for the exeeution of the method aeeording to the invention.
With the method aeeording to the invention, the reactive power of the furnaee is largely redueed, by eapaeitative ~ ~5 ~7 ~
compensation, in the area where it arises. The ind~ctive reactive power of the furnace is furthermore reduced in that the inductive resistances are lowered. The inductance, i.e. the inductive resistance in the area of the vertical high-tension line is reduced in that, in the part of the electrode between the conventional contact-jaws, and the additional compensating contact-jaws, the current flows in a direction opposite to that in the high-tension line in this area. As a result of this, the inductance-reducing effect of coaxial conductors or of bifilar conductors comes into effect.
The power-supply components, namely the high-tension power-plant, the transformer, and the high-tension lines may be made simpler and less expensive, since the reactive power to be covered is less, i.e. the apparent and connected power are less.
Furnace-operation can be improved by the use of a S~derberg electrode, since the heat arising from the flow of current in the electrode-shell above the contact-jaws may be used for preheating the mass of the electrode.
Another advantage is that less experlsive mate~rials may be used for the elect~ode phase~conductor (instead o non-magnetizable steels, as heretofore) since, in the vicinity of the vertical high-tension line, the inductance, and therefore the induction-heating, produced in the structural parts, is reduced.
The invention is explained hereinafter in greater detail, in connection with the drawings attached hereto, wherein:
~55~76 Figure 1 shows an electrode in an electric smelting furnace, with diagrammatically illustrated high-tension lines, transformers and a device according to the invention for compensating for the reactive power.
Figure 2 shows a modification of the compensating device according to the invention.
Figure 3 is a diagrammatical representation, in plan view, of three electrodes with the compensating device according to the invention.
In Figures 1 and 2, the electrode is marked 2. The high-tension line of conventional design marked 4 and 12, having a flexible section 3,connects the secondary side of a furnace-transformer 1 with contact-jaws through which the current flows to electrode 2.
In the example illustrated, additional contact-jaws 7 are provided, above contact-jaws 5, through which the three-phase voltage potential, in upper part 6 of electrode 2, is tapped and passed, through a conventional three-phase circuit (Figure 2), through a flexible conductor 8 and a rigid conductor 9, to a three-phase transformer 10. The ]atter trans.Eorms the voltage tapped from the elc:ct::rotle into a higher, more economical voltage wh:ich is fed to capacitors 11. The magni.tude of the power converted in this arrangement is determined by the level of the voltage-potential at conventional contact-jaws 5 and by the load-carrying ability of upper area 6 of electrode 2.
The inductive resistance in the vici.nity of vertical high-tension line 4 is reduced in that in area 6 of electrode 2, between conventional contact-jaws 5 and additional contact-jaws 517~
7, the current flows in the opposite direction to that in the said vertical high-tension line, thus producing the effect of coaxial conductors.
At the secondary side of additional transformer 10, at least one compensating capacitor 11 is connected to each phase of the three-phase current.
As shown in Figure 2, the three-phase voltage-potential at the electrode is tapped off by contact-jaws 5 and is passed to three-phase transformer 10 through a flow-tube 13 and conductors 8 and 9.
Method for Compensation of the Reactive Power of an Electric Smelting Furnace . . .
Operated with Three-Phase Current The invention relates to a method for compensation of the reactive power of an electric smelting furnace, operated with three-phase current, to which electrical power is supplied through a three-phase transformer, or through three single-phase transformers interconnected to a three-phase system, through high-tension lines and contact-jaws, compensating capacitors being connected to separate high-tension lines.
Energy-conversion in the electric smelting furnace is effected, under the electrodes, as Joule's heat in the so-called hearth-resistance. As the size of the furnace increases, there is a sharp drop in ohmic resistance, due to a sharp increase in the cross-sections and volumes of current-carrying structures and electrical:Ly-active, current-carrying hearth parts, and there is a sharp increase in inductive resistance.
The result of this is that, as the size of the furnace increases, the elctrical power to be installed increases to a substantlally greater degree than the thermal power to be expected from the structural expenditure.
Efforts have therefore been made to reduce inductive resistances, e.g. by the use of bifilar conductors and/or by ~.
~5S~7s~
compensating for the reactive powers, caused by inductive resistances, by means of capacitors.
It is known to decrease inductive resistances, e.g. by using bifilar eonductors (elektrow~rme international vol~s2~
1972: Dr. Mollenkamp, Dr. Kallfelz "Modern eleetric smelting furnaces for recovering ferro-alloys, pig-iron and calcium-earbide"). However, the bifilar arrangement of the conduetors, because of the furnace circuitry, is possible only in the section of line between the furnace-transformer and the flexible part of the conductor (high-tension line) permitting movement of the electrodes. The general laws governing uncompensated three-phase eonductors (R.S.T.) apply to the remaining sections of the eurrent-eonductors, namely the high-tension line along the electrode phase-conductor, through which current is passed to the eleetrodes by means of eontaet-jaws, and to the eurrent-carrying eleetrode part thereunder. The latter seetions of the high-tension conductor system aeeount for about 70~ of the total furnaee reaetive power.
It is therefore the pupose of the invention to reduee the total reaetive power of an eleetrie smelting furnaee of the type mentioned at the beginning hereof and, more partieularly, to relieve several eomponents, used to supply power, of reaetive power. The deviee for the exeeution of the method aeeording to the invention is to be of simple design. Aeeording to the invention, this purpose is aehieved by the features set forth in the eharaeterizing portion of elaim 1. The sub-elaims eontain advantageous designs of the deviee for the exeeution of the method aeeording to the invention.
With the method aeeording to the invention, the reactive power of the furnaee is largely redueed, by eapaeitative ~ ~5 ~7 ~
compensation, in the area where it arises. The ind~ctive reactive power of the furnace is furthermore reduced in that the inductive resistances are lowered. The inductance, i.e. the inductive resistance in the area of the vertical high-tension line is reduced in that, in the part of the electrode between the conventional contact-jaws, and the additional compensating contact-jaws, the current flows in a direction opposite to that in the high-tension line in this area. As a result of this, the inductance-reducing effect of coaxial conductors or of bifilar conductors comes into effect.
The power-supply components, namely the high-tension power-plant, the transformer, and the high-tension lines may be made simpler and less expensive, since the reactive power to be covered is less, i.e. the apparent and connected power are less.
Furnace-operation can be improved by the use of a S~derberg electrode, since the heat arising from the flow of current in the electrode-shell above the contact-jaws may be used for preheating the mass of the electrode.
Another advantage is that less experlsive mate~rials may be used for the elect~ode phase~conductor (instead o non-magnetizable steels, as heretofore) since, in the vicinity of the vertical high-tension line, the inductance, and therefore the induction-heating, produced in the structural parts, is reduced.
The invention is explained hereinafter in greater detail, in connection with the drawings attached hereto, wherein:
~55~76 Figure 1 shows an electrode in an electric smelting furnace, with diagrammatically illustrated high-tension lines, transformers and a device according to the invention for compensating for the reactive power.
Figure 2 shows a modification of the compensating device according to the invention.
Figure 3 is a diagrammatical representation, in plan view, of three electrodes with the compensating device according to the invention.
In Figures 1 and 2, the electrode is marked 2. The high-tension line of conventional design marked 4 and 12, having a flexible section 3,connects the secondary side of a furnace-transformer 1 with contact-jaws through which the current flows to electrode 2.
In the example illustrated, additional contact-jaws 7 are provided, above contact-jaws 5, through which the three-phase voltage potential, in upper part 6 of electrode 2, is tapped and passed, through a conventional three-phase circuit (Figure 2), through a flexible conductor 8 and a rigid conductor 9, to a three-phase transformer 10. The ]atter trans.Eorms the voltage tapped from the elc:ct::rotle into a higher, more economical voltage wh:ich is fed to capacitors 11. The magni.tude of the power converted in this arrangement is determined by the level of the voltage-potential at conventional contact-jaws 5 and by the load-carrying ability of upper area 6 of electrode 2.
The inductive resistance in the vici.nity of vertical high-tension line 4 is reduced in that in area 6 of electrode 2, between conventional contact-jaws 5 and additional contact-jaws 517~
7, the current flows in the opposite direction to that in the said vertical high-tension line, thus producing the effect of coaxial conductors.
At the secondary side of additional transformer 10, at least one compensating capacitor 11 is connected to each phase of the three-phase current.
As shown in Figure 2, the three-phase voltage-potential at the electrode is tapped off by contact-jaws 5 and is passed to three-phase transformer 10 through a flow-tube 13 and conductors 8 and 9.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of compensating for the reactive power of an electric smelting furnace operated with three-phase current, electrical power being supplied to the furnace through a three-phase transformer or through three single-phase transformers interconnected through high-tension lines, contact-jaws, and electrodes, to a three-phase system, which method comprises the steps of connecting compensating capacitors to separate high-tension lines, tapping off a three-phase voltage potential present at the electrode above the contact-jaws thereof and applying said three-phase voltage potential to the compensating capacitors, so that the current from the contact-jaws to the compensating device flows in a direction opposite to that of the current flowing to the electrode from the furnace transformer, thereby decreasing the inductance.
2. A system for compensating for the reactive power of an electric smelting furnace operated with three-phase current, electrical power being supplied to said electric smelting furnace through a three-phase transformer or through three-single phase transformers interconnected through high tension lines, contact-jaws, and electrodes, to a three-phase system, comprising compensating capacitors connected to respective separate high tension lines, means for tapping off a three-phase voltage potential, present at the electrode, above the contact-jaws thereof, and circuit means for applying the three-phase voltage potential to the compensating capacitors so that the current from the contact-jaws to the compensating device flows in a direction opposite to that of the current flowing to the electrode from the furnace transformer, thereby decreasing the inductance.
3. A system according to claim 2, having at least one additional contact provided above the contact-jaws surrounding the electrode, the said additional contact being electrically connected to at least one of said compensating capacitors.
4. A system according to claim 2, including at least one additional contact provided on the electrode above the contact-jaws surrounding the said electrode, and an additional transformer, said additional contact being electrically connected to the additional transformer and at least one said compensating capacitor being electrically connected to the secondary side thereof.
5. A system according to claim 3 or claim 4, wherein said means for tapping off the three-phase voltage potential are the contact-jaws surrounding the electrode.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2938841A DE2938841C2 (en) | 1979-09-26 | 1979-09-26 | Method for compensating the reactive power of a three-phase electric reduction furnace |
| DEP2938841.8 | 1979-09-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1155176A true CA1155176A (en) | 1983-10-11 |
Family
ID=6081825
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000361747A Expired CA1155176A (en) | 1979-09-26 | 1980-09-26 | Method for compensation of the reactive power of an electric smelting furnace operated with three-phase current |
Country Status (7)
| Country | Link |
|---|---|
| AT (1) | AT374071B (en) |
| BR (1) | BR8006159A (en) |
| CA (1) | CA1155176A (en) |
| DE (1) | DE2938841C2 (en) |
| NO (1) | NO151440C (en) |
| SE (1) | SE437752B (en) |
| ZA (1) | ZA805985B (en) |
-
1979
- 1979-09-26 DE DE2938841A patent/DE2938841C2/en not_active Expired
- 1979-11-19 AT AT0737579A patent/AT374071B/en not_active IP Right Cessation
-
1980
- 1980-09-23 SE SE8006654A patent/SE437752B/en not_active IP Right Cessation
- 1980-09-25 NO NO802840A patent/NO151440C/en unknown
- 1980-09-25 BR BR8006159A patent/BR8006159A/en not_active IP Right Cessation
- 1980-09-26 CA CA000361747A patent/CA1155176A/en not_active Expired
- 1980-09-26 ZA ZA00805985A patent/ZA805985B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ZA805985B (en) | 1981-09-30 |
| DE2938841A1 (en) | 1981-04-02 |
| BR8006159A (en) | 1981-04-07 |
| NO802840L (en) | 1981-03-27 |
| SE8006654L (en) | 1981-03-27 |
| AT374071B (en) | 1984-03-12 |
| SE437752B (en) | 1985-03-11 |
| ATA737579A (en) | 1983-07-15 |
| DE2938841C2 (en) | 1982-05-19 |
| NO151440C (en) | 1985-04-10 |
| NO151440B (en) | 1984-12-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |