Operating method for an electric arc furnace

Patent metadata

Field	Value
Publication number	US-2025142692-A1
Application number	US-202218834948-A
Country	US
Kind code	A1
Filing date	Dec 21, 2022
Priority date	Feb 7, 2022
Publication date	May 1, 2025
Grant date	—

Abstract

Based on desired values (X*) of electrical energy that is to be supplied to the electrodes, the control device of the electric arc furnace determines provisional voltage setpoint values (U1*). If voltages (U) corresponding to the provisional voltage setpoint values (U1*) are applied to the electrodes, first actual values (X) of electrical energy supplied to the electrodes would be approximated as closely as possible to the desired values (X*). The control device actuates an energy supply device of the electric arc furnace based on definitive voltage setpoint values (U2*). Voltages (U) corresponding to the definitive voltage setpoint values (U2*) are applied to the electrodes. At least during the initial melting phase, the control device determines the definitive voltage setpoint values (U2*) by limiting the provisional voltage setpoint values (U1*) to an admissible maximum value (Umax).

First claim

1 . An operating method for an electric arc furnace, wherein metal in a furnace vessel of the electric arc furnace is melted during a melting phase, wherein a control device of the electric arc furnace,
determines preliminary target voltage values (U1*) on the basis of target electrical variables (X*) of electrical energy to be supplied to the electrodes, with the result that, when voltages (U) corresponding to the preliminary target voltage values (U1*) are applied to the electrodes, first actual electrical variables (X) of electrical energy supplied to the electrodes are approximated as far as possible to the target electrical variables (X*), and controls an energy supply device of the electric arc furnace on the basis of definitive target voltage values (U2*), with the result that voltages (U) corresponding to the definitive target voltage values (U2*) are applied to the electrodes, with the result that the energy supply device draws electrical energy from a supply network and supplies it to the electrodes via a furnace transformer ( 5 ), wherein the control device, at least during a starting phase of the melting phase, determines the definitive target voltage values (U2*) by limiting the preliminary target voltage values (U1*) to a permissible maximum value (Umax), wherein the permissible maximum value (Umax) is below a possible maximum value (U0) that can be applied to the electrodes by the energy supply.

2 . The operating method as claimed in claim 1 , wherein the control device receives an input value (E) from an operator, and in that the control device determines the permissible maximum value (Umax) on the basis of the in-put value (E).

3 . The operating method as claimed in claim 1 , wherein the control device determines the permissible maximum value (Umax) on the basis of a period of time that has elapsed since the beginning of the melting phase.

4 . The operating method as claimed in claim 1 , wherein a positioning (p) of the electrodes varies over time, in that the positioning (p) of the electrodes is known to the control device, and in that the control device determines the permissible maximum value (Umax) on the basis of the positioning (p) of the electrodes.

5 . The operating method as claimed in claim 1 , wherein the control device determines progress of the melting of the metal in the electric arc furnace by evaluating the temporal progression of second actual electrical variables (U, I) of the electrical energy supplied to the electrodes and/or by evaluating actual acoustic variables of the electric arc furnace, and in that the control device determines the permissible maximum value (Umax) on the basis of the determined progress.

6 . A control program product for a control device of an electric arc furnace comprising a non-transitory computer-readable storage device and a control program stored on the non-transitory computer-readable storage device, wherein the control program comprises machine code which can be executed by the control device, wherein the execution of the machine code by the control device has the effect that the control device operates the electric arc furnace in accordance with the operating method as claimed in claim 1 .

7 . A control device of an electric arc furnace, wherein the control device comprises a non-transitory computer-readable device storing a control program, such that the control device operates the electric arc furnace in accordance with the operating method as claimed in claim 1 .

8 . An electric arc furnace,
wherein the electric arc furnace has a furnace vessel, to which metal can be supplied, wherein the electric arc furnace has an energy supply device and electrodes as well as a furnace transformer, wherein the energy supply device is connected, on the input side, to a supply network ( 4 ) and is connected, on the output side, to the electrodes via the furnace transformer, wherein the electric arc furnace has a control device which can control the energy supply device, wherein the control device is designed as claimed in claim 7 .

Assignees

• Primetals Technologies Germany Gmbh

Inventors

• Matschullat Thomas

Classifications

• F27B3/28

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

• F27D19/00

  Arrangements of controlling devices · CPC title

• F27D2019/0037

  Quantity of electric current · CPC title

• F27B3/085

  Arc furnaces · CPC title

• H05B7/148 Primary

  Automatic control of power (electrode feeding arrangements H05B7/109; automatic feeding of electrodes for spot or seam welding or cutting B23K9/12; disposition of electrodes in or on furnaces F27D11/10; control of position in general G05D3/00; regulating electric characteristics of arcs in general G05F1/02; regulating electric power in general G05F1/66) · CPC title