Method and apparatus for measuring the length of an electrode in an electric arc furnace

Patent metadata

Field	Value
Publication number	US-2018067201-A1
Application number	US-201715812462-A
Country	US
Kind code	A1
Filing date	Nov 14, 2017
Priority date	May 15, 2015
Publication date	Mar 8, 2018
Grant date	—

Abstract

A method for determining a length parameter of an electrode during operation of an electric arc furnace. An internal duct extends through the length of the electrode and is open at its lower end. A waveguide having a solid core is received in the internal duct and comprises a material having a low dielectric constant and high temperature resistance. The solid core of the waveguide includes at least one target. An electromagnetic radiation signal is emitted from a source and transmitted through the waveguide and the signal is diffracted and/or reflected from at least one target to produce at least one return signal which is transmitted back through the waveguide. A time or frequency difference between the emitted signal and the return signal is measured and the length parameter is calculated based on this difference.

First claim

What is claimed is:

1 . A method for determining a length parameter of an electrode during operation of an electric arc furnace containing a bath, the method comprising:
(a) providing the electrode, wherein the electrode has an upper end situated outside the furnace, a lower end situated inside the furnace, a length defined from the upper end to the lower end, and an internal duct extending along the length of the electrode, wherein the internal duct is open at the lower end of the electrode; (b) providing a waveguide having a first end, a second end and a solid core, wherein the waveguide is at least partly received in the internal duct of the electrode with its second end located at or proximate to the lower end of the electrode, wherein the solid core of the waveguide includes at least one target; (c) emitting an electromagnetic radiation signal, from a source and transmitting the emitted signal through the solid core from the first end toward the second end of the waveguide; (d) diffracting and/or reflecting the emitted signal from the at least one target to produce at least one return signal and transmitting the at least one return signal through the solid core from the at least one target toward the first end of the waveguide; (e) receiving the at least one return signal from the solid core at the first end of the waveguide; (f) measuring a time or frequency difference between the emitted signal and the at least one return signal; and (g) calculating the length parameter based on this difference.

2 . The method according to claim 1 , wherein the bath contains one or more molten materials selected from molten metal, molten matte, and molten slag.

3 . The method according to claim 1 , wherein the lower end of the electrode is in contact with the one or more molten materials in the bath.

4 . The method according to claim 1 , wherein the lower end of the electrode has a tip, and wherein the internal duct is open at the tip of the electrode.

5 . The method according to claim 1 , wherein the internal duct extends throughout the length of the electrode from the upper end to the lower end, and is open at the upper end of the electrode.

6 . The method according to claim 1 , wherein the waveguide extends throughout the length of the electrode from the upper end to the lower end.

7 . The method according to claim 1 , wherein the waveguide has an outer surface which is in contact with an inner wall of the internal duct.

8 . The method according to claim 1 , wherein the electrode is a prebaked carbon electrode comprised of a plurality of segments joined together end-to-end.

9 . The method according to claim 1 , wherein the electrode is a Soderberg electrode formed by baking a carbon paste within an outer metal casing.

10 . The method according to claim 1 , wherein the length parameter is selected from one or more of: the length of the electrode from its upper end to its lower end; the length of a portion of the electrode; and the position of the lower end of the electrode relative to a fixed point on the furnace.

11 . The method according to claim 1 , wherein the solid core comprises a plurality of segments joined together end-to-end; and wherein the length parameter comprises the number of segments in the solid core.

12 . The method according to claim 1 , wherein the at least one target comprises a tip of the solid core which is directly exposed to the molten bath at the lower end of the electrode.

13 . The method according to claim 1 , wherein the at least one target comprises one or more discontinuities located along a length of the solid core.

14 . The method according to claim 13 , wherein each of the one or more discontinuities comprises a notch or a joint.

15 . The method according to claim 1 , wherein the solid core comprises a rigid, elongate bar or rod.

16 . The method according to claim 1 , wherein the material comprising the solid core is a ceramic.

17 . The method according to claim 1 , wherein the material comprising the solid core has a dielectric constant greater than the dielectric constant of air.

18 . The method according to claim 1 , wherein the material comprising the solid core has a maximum use temperature with an upper limit at or below the temperature of the arc emitted by the electrode.

19 . The method according to claim 18 , wherein a lower limit of the maximum use temperature is about 300° C.

20 . The method according to claim 19 , wherein the lower limit of the maximum use temperature is about 500° C.

21 . The method according to claim 1 , wherein the emitted signal and the at least one return signal comprise electromagnetic radiation.

22 . A method for determining a position of a slag/metal interface in a bath of an electric arc furnace relative to a fixed component of the furnace, the method comprising:
(a) determining a length parameter of an electrode during operation of the electric arc furnace according to the method of claim 1 , wherein the length parameter is the length of the electrode from its upper end to its lower end; (b) with the lower end of the electrode located in the bath, raising or lowering the electrode; (c) monitoring one or more electrical parameters of the electrode as it is being raised or lowered; (d) continuing to raise or lower the electrode until the monitoring of the electrical parameters indicates that the lower end of the electrode has passed through the slag/metal interface; and (e) calculating the position of the slag/metal interface relative to the position of fixed component, based on the length of the electrode determined in step (a), the position of the slag/metal interface determined in step (d), and the known position of the fixed component.

23 . The method according to claim 22 , wherein the fixed component of the furnace is the hearth.

24 . An apparatus for measuring a length parameter of an electrode of an electric arc furnace, wherein the electrode has an upper end situated outside the furnace, a lower end situated inside the furnace, a length defined from the upper end to the lower end, and an internal duct extending along the length of the electrode, wherein the internal duct is open at the lower end of the electrode, the apparatus comprising:
(a) a waveguide having a first end, a second end, and a solid core, wherein the waveguide is adapted to be at least partly received in the internal duct of the electrode, wherein the solid core of the waveguide includes at least one target; (b) a wave generator adapted to emit an electromagnetic radiation signal into the solid core at the first end of the waveguide; and (c) a wave receiver adapted to receive an electromagnetic radiation signal from the solid core at the first end of the waveguide.

25 . The apparatus according to claim 24 , wherein the solid core comprises a plurality of segments joined together end-to-end.

26 . The apparatus according to claim 24 , wherein the at least one target comprises a tip of the solid core or at least one discontinuity located along a length of the solid core.

27 . The apparatus according to claim 24 , wherein the at least one discontinuity comprises at least one notch or at least one joint.

28 . The apparatus according to claim 24 , wherein the solid core comprises a rigid, elongate bar or rod.

29 . The apparatus according

Assignees

• Hatch Ltd

Inventors

• Cramer Matthew H
• Sadri Afshin
• Erskine Jennifer
• Chataway David
• Wasmund Bert O
• Gerritsen Terry

Classifications

• F27B3/28

  Arrangement of controlling, monitoring, alarm or the like devices · CPC title

• F27B3/085

  Arc furnaces · CPC title

• F27D21/00

  Arrangement of monitoring devices; Arrangement of safety devices · CPC title

• G01S13/88

  Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) · CPC title

• G01F23/284

  Electromagnetic waves · CPC title