Siemens Aktiengesellschaft

Primetals Technologies Germany Gmbh

Detlef Rieger

Thomas Matschullat

Arno Döbbeler

Klaus Krüger

Dieter Fink

Björn Dittmer

Detlef Gerhard

Martin Hergt

Wolfgang Meusel

Arno Doebbeler

Sascha Leadbetter

Ralf Engels

Reinhard Sesselmann

An electric arc furnace () operated with alternating current has a converter () which converts mains voltage (U), into primary voltage (U') having a furnace frequency (f&#x2032;). A furnace transformer () transforms the primary voltage (U&#x2032;) into a secondary voltage (U&#x2033;), supplied to electrodes () in a furnace vessel () (). They apply electric arcs () to a melt material () in the vessel (). The secondary voltage (U&#x2033;) is also supplied to a capacitor assembly () on the output side of the furnace transformer () and the furnace transformer () is connected on the output side. A control device () controls the converter () such that a primary voltage (U&#x2032;) output from the converter () to the furnace transformer () has a furnace frequency (f) of least ten times the mains frequency (f) and/or greater than 1 kHz.

Converter-fed electric arc furnace with capacitor assembly in the secondary circuit

Flicker values to be expected may be determined and achieve a high probability from suitable state and operating variables which are acquired during the first minutes in the initial smelting phase. In this way, flicker can effectively be reduced and kept below predefined limiting values. This is in particular suitable during steel production using electric arc furnaces.

Flicker reduction in electric arc furnaces by means of flicker prediction from the state determination in the initial phase of the smelting process

In a method for operating an electric arc furnace operated with an alternating voltage, a structure-borne sound signal occurring on a wall of the electric arc furnace is detected, from which structure-borne sound signal a parameter characterizing the flicker properties of the electric arc furnace is calculated. At least one process variable of the electric arc furnace is controlled on the basis of the calculated parameter. An electric arc furnace operated according to the method is used in and for a melting plant.

Method for operating an electric arc furnace and melting plant having an electric arc furnace operated according to said method

A method for controlling a melt process in an arc furnace, including a signal processing component, program code, and data medium for performing the method. Sound signals or vibrations from the interior of the furnace container are captured by solid-borne sound sensors, from which characteristic values can be derived representing the distribution of melting material, melt, and slag in the furnace fill. A characteristic values are generated in priority sequence for: thermal radiation impinging on the furnace wall of the container, the lumpiness of the melting material in the volume of furnace fill, and the change to the portion of solid melting material contacting the furnace wall. The energy distribution at the electrodes is chanced by a control system based on the characteristic values in priority sequence, such that thermal load peaks are dampened or even completely prevented.

Method for controlling a melt process in an arc furnace and signal processing component, program code and data medium for performing said method

In a method for determining a state variable of an electric arc furnace, especially for determining the level of the foamed slag () in a furnace, the energy supplied to the furnace is determined with the aid of at least one electric sensor while solid-borne noise is measured in the form of oscillations on the furnace. The state variable is determined by a transfer function which is determined by evaluating the measured oscillations and evaluating measured data of the electric sensor. The state of the foamed slag level can thus be reliably recognized and be monitored over time. The foamed slag level is decisive for the effectiveness with which energy is fed into the furnace. Furthermore, losses caused by radiation are reduced by covering the arc with the foamed slag. The improved measuring method allows the foamed slag level to be automatically controlled or regulated in a reliable manner.

Method for determining at least one state variable of an electric arc furnace, and electric arc furnace

In a method for operating an arc furnace () with at least one electrode (), a solid material fed to the arc furnace () is melted by an arc () formed by the at least one electrode (). A measurement (MM) for the mass of one part of the solid material arranged on a boundary () of the arc furnace () is determined, and using the determined measurement (MM), a process variable of the arc furnace () is controlled and/or regulated. A method which can reduce the risk of electrode damage caused by metal scraps falling into the treated area is provided.

Method for operating an arc furnace comprising at least one electrode, regulating and/or control device, machine-readable program code, data carrier and arc furnace for carrying out said method

In a method, a variable characterising an operational state of an electrode of an arc furnace can be determined. An electrode flow guided to the electrode is detected in the method and the structure-borne noise oscillations are detected. From the detected electrode flow, a flow evaluation signal associated with the frequency range of the detected electrode flow is determined. From the detected structure-borne noise oscillations, an oscillation evaluation signal that is associated with a frequency range of the detected structure-borne noise oscillations is detected and a quotient from the oscillation evaluation signal and the flow evaluation signal is formed as a radiation measurement for at least one frequency common to the detected electrode flow and the detected structure-borne noise oscillation.

Method for determining a radiation measurement for thermal radiation, arc furnace, a signal processing device programme code and storage medium for carrying out said method

In a method for determining the size and shape value (M) for a solid material (S), in particular scrap metal, in an arc furnace (), an electrode flow fed to an electrode () for forming an arc furnace (L) between the electrode () and the solid (S) is measured () and from the measured electrode flow (I (t)), an effective measurement value of the electrode flow is determined () and from the measured electrode flow (I (t)) (), a flow part associated with a frequency range of the measured electrode flow is determined (), and a quotient of the flow part and an effective measurement value is formed as a measurement of the shape and size value of the flow (M). Thus, a method is provided that enables a property of a fusible element introduced into one of the arc furnaces to be determined.

Method for determining the size and shape measure of a solid material in an arc furnace, an arc furnace, a signal processing device and program code and a memory medium

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Baldham, Germany

Detlef Rieger