Back to results
US 6,584,137 B1Granted
Method for making steel with electric arc furnace
AssigneeNucor Corporation
InventorsThomas Michael Dunn, Erik Rene Ocklind Nissen
Life of this patent
Estimating the term…
Abstract
A method of making steel in an electric arc furnace is provided. The method comprises the steps of measuring electrical current in at least two phases of electrical power supplied to electrodes in the furnace during a campaign, establishing a setpoint current level and an input time interval, and switching between modes of inputting exothermic energy into the steel melt when at least two phases have measured current levels below the setpoint for the input time interval.
Claims29
A method of making steel in an electric arc furnace comprising the steps of:
- (a) measuring the electrical current in at least two phases of three (3) phases of electrical power through electrodes into a steel melt in an electric arc furnace during a campaign;
- (b) establishing at least one setpoint current level for the measured electrical current and input time interval for said setpoint current level for switching between modes of inputting exothermic energy into the steel melt in the electric arc furnace during the campaign;
- (c) switching between the modes of inputting exothermic energy based on measuring the electrical current in the measured phases of electrical power input through the electrodes of the furnace to determine when at least two (2) of the three (3) phases have measured current levels below the setpoint for the input time interval.
A method of making steel in an electric arc furnace comprising the steps of:
- (a) measuring the electrical current in at least two of three (3) phases of electrical power transmitted to electrodes in an electric arc furnace during a campaign;
- (b) establishing at least one setpoint current level for the measured electrical current and input time interval for said setpoint current level for switching between modes of electric energy input into a steel melt in the electric arc furnace during a campaign;
- (c) switching between modes of inputting electrical current through the electrodes in the electric arc furnace when the electrical current levels in at least two of the three phases of electric power are determined to be below the input setpoint for the input time interval.
A method of making steel in an electric arc furnace comprising the steps of:
- (a) measuring the current in at least two of three (3) phase of electric power to electrodes of an electric arc furnace during a campaign;
- (b) establishing at least one input setpoint in the measured electrical current levels and input time intervals for said electrical current levels for switching between the following three modes of inputting exothermic energy into the steel melt in the electric arc furnace during a campaign:
- (i) first mode, inputting heat to the steel scrap in the furnace by combustion of a combustion fuel/oxygen mixture flow through one or more oxy-fuel burners to melt scrap or other iron sources charged to the furnace, where said mixture is high in combustion fuel with sufficient oxygen to combust at least most of the combustion fuel;
- (ii) second mode, inputting heat to the partially melted scrap or other iron sources in the furnace by combustion of a combustion fuel/oxygen mixture where said mixture has a reduced flow of combustion fuel flow and increased oxygen flow capable of cutting a hole through scrap to provide a path for oxygen injection into the melt;
- and
- (iii) third mode, injecting oxygen into the molten metal bath in the furnace to provide for decarbonization, dephosphorization and refining;
- (c) switching between the three modes of inputting exothermic energy based on measuring the electrical current of at least two of three phases of electric power input to the electrodes of the furnace and determining when at least two of the three phases are determined to be below an input setpoint electrical level for an input time interval.
4 more elements
A method of making steel in an electric arc furnace comprising steps of:
- (a) measuring the electrical current in at least two phases of three-phase electrical power to electrodes in an electric arc furnace;
- (b) establishing input setpoints of measured electrical current levels and input time intervals for said electrical current levels for switching between the following three modes of electrical inputting current through the electrodes to a steel melt in the electric arc furnace during a campaign:
- (i) first mode, inputting energy in the form of electric current arcing from electrodes to scrap within the furnace in a short arc;
- (ii) second mode, inputting energy in the form of electric current into the melt through the electrodes primarily to melt the scrap and other sources of iron in the furnace;
- (iii) third mode, inputting energy in the form of electric power through electrodes into molten steel bath in the furnace to increase the temperature of the molten steel and to provide for decarbonization, dephosphorization and other refining;
- (c) switching between the three modes based on measuring the electrical current in at least two of the three phases of electric power input to the electrodes in the electric arc furnace when the electrical current in two of the three phases are determined to be below an input setpoint for an input time interval.
3 more elements
Dependencies are inferred from the claim text.