Converter Dephosphorization Control Using Slag Thickness Feedback
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Solution Overview
Problem
Conventional dephosphorization methods for top and bottom blown converters fail to efficiently supply iron oxide (FeO) to the slag-metal interface, leading to reduced reaction efficiency and potential slopping due to excessive iron oxide accumulation in the slag.
Innovation Solution
A molten iron dephosphorization method using a top-blowing lance that supplies oxygen-containing gas through main holes penetrating the slag, with a control gas adjusting the jetting conditions based on slag thickness measurements to ensure contact with the molten iron, preventing excessive iron oxide accumulation and slopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the top-blown oxygen jet flow is blocked by slag to prevent direct contact with molten iron, then oxygen activity at the slag-metal interface is enhanced and dephosphorization efficiency increases, but iron oxide accumulates excessively in the slag causing slopping
Solution Approach 1:
The lance height is dynamically adjusted during the blowing process based on real-time measurement of slag layer thickness. The control system continuously monitors slag level and modifies the lance height to maintain optimal oxygen jet penetration, enabling the system to adapt between preventing direct contact (for efficiency) and allowing controlled contact (to prevent iron oxide accumulation and slopping)
Solution Approach 2:
A feedback control system measures the slag layer thickness in real-time and uses this information to adjust the lance height. The measurement device continuously monitors the slag level, and the control system processes this data to automatically modify the lance position, creating a closed-loop control that balances dephosphorization efficiency with prevention of slopping
2Quantity of substance
If the top-blowing lance height is reduced to allow oxygen contact with molten iron, then iron oxide supply to the slag-metal interface increases, but the oxygen jet may cause excessive agitation and dust generation
Solution Approach 1:
The slag layer serves as an intermediary medium between the top-blown oxygen jet and the molten iron. By controlling the lance height to allow oxygen to penetrate through the slag layer rather than directly contacting the molten iron, the system achieves iron oxide supply to the slag-metal interface while the slag acts as a buffer that reduces excessive agitation and dust generation
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
Stable supply of iron oxide (FeO) to the slag-metal interface enhances dephosphorization efficiency while preventing slopping, maintaining operational stability in top and bottom blown converters.
Implementation Method 1
a top-blown jet flow of an oxygen-containing gas penetrates through the slag 7
Implementation Method 2
FeO in the slag is generated as the oxygen-containing gas jetted out from the top-blowing lance is absorbed by molten iron at a hot spot and oxidizes the iron
Implementation Method 3
supplies a control gas from an opening disposed in an inner wall surface of the blowing main hole toward an axial center of the blowing main hole through a control gas supply passage
Implementation Method 4
the lime turns into slag by reacting with iron oxide to form calcium ferrite (CaO·FeO) with a low melting point, thereby contributing to the dephosphorization reaction
Data Source
AI summary
A dephosphorization method using a top and bottom blown converter. This method uses a converter charged with molten iron and slag, to blow an oxygen-containing gas from a top-blowing lance, supply the gas from an inlet of a blowing hole, and supply a control gas from an opening toward an axial center. This method has: a slag top-surface position measurement step, with the top surface of the molten iron measured in advance, measuring an arbitrary position in a top surface of the slag; a slag top-surface difference calculation of slag thickness difference between the measured top-surface positions of the molten iron and the slag; and a jetting condition adjustment step of, using the obtained slag thickness, adjusting a jetting condition of the gas jetted from the top-blowing lance into an appropriate range. The top-blown jetting condition is adjusted by comparing the slag thickness and the depth of a surface depression.