Top Blowing Lance Oxygen Accumulation Index Control
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Solution Overview
Problem
During decarburization refining in converters, excessive oxygen supply leads to iron scattering, adhering, and deposition on the converter walls and throat, resulting in reduced productivity and increased costs due to inefficient oxygen utilization and sloshing phenomena.
Innovation Solution
A method is implemented where the oxygen gas flow rate per unit hot spot area is determined and the oxygen accumulation index is controlled by adjusting the oxygen feeding rate and lance height, ensuring the index remains within a predetermined range to suppress oscillation and bubble burst, thereby reducing iron loss and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the oxygen feeding rate is increased to improve productivity, then the decarburization rate increases, but iron scattering and dust generation increase
Solution Approach 1:
The patent applies parameter changes by controlling the oxygen gas flow rate per unit hot spot area within a specific range (0.5-2.0 Nm³/s per m²) and maintaining the oxygen accumulation index within predetermined limits. This optimization of operational parameters enables high productivity while minimizing iron scattering and dust generation, resolving the contradiction between increased oxygen feeding rate and reduced iron loss.
2Productivity
If the oxygen feeding rate is increased to improve productivity, then the decarburization rate increases, but iron adhering and deposition on converter walls increases
Solution Approach 1:
The patent controls the oxygen accumulation index within predetermined limits by adjusting the oxygen feeding rate and lance height parameters. This parameter optimization prevents excessive oxygen accumulation that causes iron adhering and deposition on converter walls, thereby maintaining high productivity while reducing iron loss through deposition.
3Productivity
If the oxygen gas flow rate per unit hot spot area is increased, then the decarburization efficiency improves, but the oxygen accumulation index increases causing oscillation and bubble burst
Solution Approach 1:
The patent optimizes the oxygen gas flow rate per unit hot spot area within a specific range (0.5-2.0 Nm³/s per m²) and controls the oxygen accumulation index within predetermined limits. This parameter control prevents excessive oxygen accumulation that would cause molten iron oscillation and bubble burst, while maintaining high decarburization efficiency through optimized oxygen supply.
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 effectively suppresses the oscillation of molten iron, reduces iron adhering and deposition, and maintains high oxygen efficiency, leading to increased productivity and reduced operational costs by controlling the oxygen accumulation index within a specific limit.
Implementation Method 1
blowing oxygen gas on the surface of the molten iron in the converter through the one or more Laval nozzles
Implementation Method 2
an oxygen jet and molten iron, i.e., a 'cavity' called 'hot spot'
Implementation Method 3
the collision interface between an oxygen jet and molten iron, i.e., a 'cavity' called 'hot spot'
Implementation Method 4
decarburization reaction with top-blown oxygen proceeds mainly in the collision interface between an oxygen jet and molten iron
Implementation Method 5
Dust is generated by a bubble burst (for example, spitting (scattering of metal) or scattering of granular iron due to bubbles separated from molten metal)
Data Source
Figure 1~2
Figure 3
AI summary
When the decarburization refining of molten iron is performed by top-blowing oxygen gas from the top blowing lance, the oscillation of molten iron, a bubble burst, and spitting due to the bubble burst are suppressed. A refining method for a converter includes decarburizing molten iron in the converter with a top blowing lance having Laval nozzles disposed at the lower end thereof by blowing oxygen gas on the surface of the molten iron in the converter through the Laval nozzles, in which one or both of an oxygen feeding rate from the top blowing lance and lance height LH are adjusted in such a manner that an oxygen accumulation index S(F) is 40 or less.