Level-Based Steel Tapping Control for Ladle Consistency
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Solution Overview
Problem
Current steel tapping methods to a consistent weight in electric arc furnaces result in variability of the steel level in the ladle, leading to increased costs due to the need for more refractory material, longer electrodes, and potential crane capacity issues, while also limiting production rate and efficiency.
Innovation Solution
A method and apparatus that allow steel to be tapped to a predetermined level (freeboard) in the ladle, using predictive algorithms to determine the weight and duration of the tap, enabling accurate scrap and alloy additions, and employing infrared imaging to detect excessive slag, thereby maximizing yield and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If steel is tapped to a consistent weight, then the tap weight is controlled, but the steel level in the ladle varies due to refractory lining wear, increasing costs and limiting production efficiency
Solution Approach 1:
The patent changes the control parameter from weight-based to level-based tapping. By monitoring the steel level in the ladle and tapping to a predetermined level rather than a target weight, the system adapts to refractory lining wear and maximizes the utilization of ladle volume, thereby increasing production rate while maintaining process control
Solution Approach 2:
The system performs preliminary calculations to determine the predetermined level and expected tap weight before the tapping operation begins. This allows operators to plan scrap and alloy additions in advance, optimizing the tapping process and enabling higher production rates without sacrificing quality control
2Reliability
If steel level varies in the ladle, then more refractory material is needed at the slag line, but tapping to consistent weight causes this variability
Solution Approach 1:
By changing from weight-based to level-based control, the steel level in the ladle remains consistent throughout the refractory lining campaign. This eliminates the need for excessive refractory material at the slag line, reducing material consumption and cost
3Reliability
If electrodes are made longer to accommodate variable steel levels, then the steel level can be covered, but electrode cost and oxidation rate increase
Solution Approach 1:
Level-based control maintains consistent steel levels, eliminating the need for longer electrodes with greater range of motion. This reduces electrode consumption and oxidation rates, lowering operational costs
4Productivity
If ladle is filled to maximum capacity, then production efficiency increases, but crane capacity may be exceeded
Solution Approach 1:
The system performs preliminary calculations to determine both the predetermined level and the expected tap weight before tapping. This allows advance planning to ensure crane capacity is not exceeded while maximizing ladle utilization, balancing productivity with operational constraints
Data Source
AI summary
A method of tapping a steelmaking furnace comprised of determining a desired level of steel to be attained in a ladle, and calculating the weight of molten steel that will be present when the desired level is attained following a transfer of molten steel from the furnace to the ladle. The furnace is operated such that slag is formed on top of molten steel contained therein. The furnace is moved to a first position to cause transfer of molten steel to the ladle to begin. The transfer of molten steel from the furnace to the ladle is continued, and at the first occurrence of molten steel attaining the desired level in the ladle, molten steel attaining a maximum allowable weight in the ladle, or an excessive amount of slag being present upon the molten steel in the ladle, transfer of molten steel to the ladle is ceased.