Industrial electric heating furnaces – Electroslag remelting device – Power supply system
Reexamination Certificate
1999-11-15
2001-01-23
Hoang, Tu Ba (Department: 3742)
Industrial electric heating furnaces
Electroslag remelting device
Power supply system
C373S049000, C373S105000
Reexamination Certificate
active
06178191
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for determination of the electrode tip position for consumable electrodes used in electric smelting furnaces, and particularly electrodes used in furnaces where the electrodes are submerged in the furnace charge during operation of the furnaces.
BACKGROUND ART
In electric smelting furnaces for the production of ferro alloys, silicon, pig iron etc., it is used consumable carbon electrodes which during operation of the furnace are submerged in the furnace charge. The electrodes are being held by electrode holders to which also electric operating current is being supplied to the electrodes. The electrodes are being regulated up and down in vertical direction by means of hydraulic cylinders in order to maintain a preset electrode current or a preset electric resistance. The electrode holder system further comprises means for slipping of the electrodes through the electrode holders to compensate for the electrode consumption.
The electrode tip positions in the furnace are important regulating parameters for operation of electric smelting furnaces. It has, however, been found that it is difficult to determine the electrode tip position at a sufficient accuracy. Conventionally, the electrode tip positions are measured by manual measurements which can only be done at long time intervals as manual determinations of electrode tip positions requires that the charge is melted down, whereafter the furnace has to be shut down in order to manually determine the electrode tip positions. This procedure causes interruption of the furnace operation and is therefore done as seldom as possible.
A number of other methods have been proposed for determination of the electrode length and the electrode tip position for electrodes in electric smelting furnaces. None of these methods have, however, found any use in practice. Electrode tip position as used herein shall mean the vertical position of the lower end of the electrode measured relative to a reference point on the smelting furnace. The reference point can for instance be the bottom of the smelting furnace. The electrode tip position will in this case be determined as the distance between the electrode tip and the furnace bottom.
DISCLOSURE OF INVENTION
By the present invention one has arrived at a simple method for determination of the electrode tip position for electrodes in electric smelting furnaces.
Accordingly, the present invention relates to a method for determination of the electrode tip position for consumable electrodes in electric smelting furnaces, said electrodes being submerged in the furnace charge, which method is being characterized in that the voltage between two geometrically displaced points on the outside of the steel wall of the furnace pot is measured during operation of the furnace, said points being situated as close as possible to the electrode for which the electrode tip position is to be determined, and as far away as possible from the other electrodes in the furnace, that the electrode current for the electrode for which the electrode tip position is to be determined, is recorded at the same time as the voltage between the two points are measured, whereafter the difference between measured voltage between the two points and measured electrode current is calculated, and where the absolute value of said difference increases when the electrode tip position increases and decreases when the absolute value of said difference decreases.
According to a preferred embodiment of the present invention the electrode tip position is determined according to the following formula:
E
tp
=RP+b
(
a
×voltage−electrode current),
where E
tp
=electrode tip position,
RP=a fixed reference point on the furnace,
voltage=voltage measured between the two points on the steel furnace pot, and where
a and b are constants which have to be established for each electrode.
The two points on the outside of the steel wall of the furnace pot which are geometrically displaced, can be situated freely. Thus they can favorably be situated both on a vertical line and on a horizontal line, and in fact in any other configuration.
It has very surprisingly been found that there exists a close correlation between the electrode tip position and voltage measured on the furnace wall just outside the electrode for which the electrode tip position is to be determined.
From the above formula it is seen that if the electrode current is constant, the change in electrode tip position is only dependant on the measured voltage difference between the two points on the steel wall of the furnace pot.
The method according to the present invention can be used for all types of electric furnaces and processes where one uses submerged consumable electrodes. The method can thus be used both for furnaces having a circular cross-section and for furnaces having a rectangular cross-section. The method can be used both for alternating current furnaces equipped with one electrode as well as for furnaces equipped with more than one electrode.
The method according to the present invention is preferably used for stationary furnaces, but tests have shown that it also can be used to determine electrode tip position for electrodes in rotating furnaces. Rotating furnaces are particularly used for the production of silicon. When the method according to the present invention is used to determine electrode tip position for electrodes in rotating furnaces, one must, in order to obtain good results, use a number of measuring points about the circumference of the furnace wall in order to always be able to measure the voltage between two points on the furnace wall as close as possible to the electrode for which the electrode tip position is to be determined.
REFERENCES:
patent: 3619464 (1971-11-01), Holzgruber et al.
patent: 4096344 (1978-06-01), Munson
patent: 4349912 (1982-09-01), Bello
patent: 4395771 (1983-07-01), Medovar et al.
patent: 5115447 (1992-05-01), Bowman
patent: 5687187 (1997-11-01), Weischedel et al.
patent: 5930284 (1999-07-01), Hysinger et al.
patent: 362703 (1973-12-01), None
Kalgraf Kjell
Morkesdal Gunnar
Tronstad Ragnar
Bierman, Muserlian and Lucas
Elkem ASA
Hoang Tu Ba
LandOfFree
Method for determination of the tip position of consumable... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for determination of the tip position of consumable..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for determination of the tip position of consumable... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2536030