Electric Arc Furnace Refractory Wear Reduction via Preheating
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Solution Overview
Problem
Conventional metal melting processes in continuous loading electric arc furnaces face high refractory wear, frequent maintenance, and inefficient energy use due to high temperatures and reactivity of molten steel, leading to increased operational costs and reduced productivity.
Innovation Solution
A method that regulates the loading of metal material to maintain a controlled amount of solid mass within the furnace, reducing the temperature of the molten metal and using auxiliary heat sources to optimize energy use, while minimizing refractory wear and contamination, by loading a large mass initially and then maintaining a solid accumulation to control the melting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the quantity of material defining the hot heel is increased to 50% of liquid metal, then the melting step can start quickly after tapping, but the wear on the refractory lining increases extensively
Solution Approach 1:
The patent changes the critical parameter of hot heel quantity from the conventional 50% to a reduced amount (10-30% of liquid metal volume). This parameter change allows the refractory to withstand the thermal and mechanical stress for a longer period while still maintaining enough liquid metal to quickly restart the melting process after tapping.
Solution Approach 2:
The patent introduces a preheating shaft that preliminarily heats the metal charge before it enters the melting furnace. This preliminary action reduces the thermal shock to the refractory when cold charge is introduced, thereby reducing refractory wear while maintaining productivity.
2Ease of operation
If the bath of molten steel is maintained at high temperature (1600-1650°C) to enable tapping, then the molten steel has high reactivity and high turbulence, but this causes great wear on the refractory walls
Solution Approach 1:
The patent introduces a preheating shaft as an intermediary device between the charge loading system and the melting furnace. This intermediary preheats the charge before it enters the high-temperature zone, reducing the thermal gradient and turbulence in the molten steel, thereby reducing refractory wear while maintaining tapping capability.
Solution Approach 2:
The patent implements a dynamic process where the charge is progressively heated in the preheating shaft before entering the furnace, and the molten steel level is dynamically controlled. This dynamic approach reduces sudden thermal shocks and turbulence, minimizing refractory wear while preserving the ability to tap at appropriate temperatures.
3Use of energy by stationary object
If auxiliary energy supply means (combustible gas burners) are disposed on the furnace walls to heat the scrap load, then heat energy is supplied, but the burners must be at a determinate distance from the metal bath to preserve their integrity, which reduces efficiency
Solution Approach 1:
The preheating shaft acts as an intermediary zone where combustible gas burners can be positioned closer to the metal charge without directly exposing them to the high-temperature molten steel bath. The shaft provides a protective environment that allows efficient heat transfer while preserving burner integrity, thus resolving the contradiction between energy efficiency and equipment protection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces refractory wear, decreases maintenance frequency, improves steel quality, and increases overall productivity by maintaining a lower molten metal temperature and efficiently utilizing energy, allowing for quicker restarts and reduced contamination.
Implementation Method 1
an electric arc furnace associated with means to feed the metal charge
Implementation Method 2
the refractory that lines the inner walls of the furnace
Implementation Method 3
high turbulence due to the high convective motions that take place inside it
Implementation Method 4
the exothermic oxidation reactions of the alloy elements of the iron
Data Source
AI summary
Method for melting metal material in a melting plant comprising at least an electric furnace having at least a shell into which said metal material is introduced, and feed means to load said metal material into said shell, said method comprising at least a step of loading said metal material into said shell by means of said feed means, a melting step in which said metal material is melted, and a subsequent tapping step in which the molten metal material is tapped.