Top-Blowing Lance Jetting Control for Molten Iron Dephosphorization
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Solution Overview
Problem
Conventional dephosphorization methods in top and bottom blown converters face inefficiencies due to oxygen jet flow penetration issues and excessive iron oxide accumulation, leading to slowed reactions and operational hazards like slopping.
Innovation Solution
The method involves adjusting the top-blowing lance's jetting conditions by controlling the ratio of control gas supply pressure to main gas supply pressure and control gas flow rate to main gas flow rate, ensuring the oxygen jet penetrates through the slag and maintains contact with molten iron, preventing excessive iron oxide accumulation and promoting efficient dephosphorization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the top-blown oxygen jet flow is blocked by slag from directly contacting molten iron, then oxygen activity at the slag-metal interface is enhanced and dephosphorization efficiency increases, but excessive iron oxide accumulates in the slag leading to slopping hazards
Solution Approach 1:
The invention changes the parameter of oxygen jet flow penetration depth through the slag layer. By controlling the jet flow to penetrate to a specific depth (0.1-0.5 times the slag layer thickness) rather than being completely blocked or fully penetrating through, the patent optimizes both dephosphorization efficiency and prevents excessive iron oxide accumulation that causes slopping.
2Productivity
If the top-blown oxygen jet flow directly contacts molten iron, then iron oxide is generated and supplied to the slag-metal interface, but dust concentration increases extremely and dephosphorization efficiency decreases
Solution Approach 1:
The invention uses the slag layer as an intermediary medium between the top-blown oxygen jet and the molten iron. By controlling the jet to penetrate partially through the slag rather than directly contacting the iron, the slag acts as a mediator that reduces dust generation while still allowing sufficient iron oxide supply for dephosphorization.
3Quantity of substance
If the oxygen jet flow penetrates deeply through the slag, then direct contact with molten iron occurs and iron oxide supply increases, but the jet flow is blocked by slag and oxygen activity at the interface is reduced
Solution Approach 1:
The invention optimizes the penetration depth parameter of the oxygen jet through the slag layer. By setting the penetration depth to 0.1-0.5 times the slag layer thickness, the patent achieves an optimal balance where sufficient iron oxide is generated and supplied to the interface while maintaining high oxygen activity for effective dephosphorization.
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 stabilizes iron oxide supply to the slag-metal interface, enhancing dephosphorization efficiency while preventing slopping, ensuring safe and effective operation in top and bottom blown converters.
Implementation Method 1
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 2
the vertical component V of the jet velocity at the nozzle leading end of the oxygen-containing gas jetted from the top-blowing lance
Data Source
Figure 1
Figure 2
AI summary
Proposed is an efficient dephosphorization method using a top and bottom blown converter. This molten iron dephosphorization method uses a top and bottom blown converter charged with molten iron and slag, and to blow an oxygen-containing gas from a top-blowing lance, supplies the oxygen-containing gas as a main gas from an inlet of a blowing main hole, and supplies a control gas from an opening toward an axial center of the blowing main hole through a control gas supply passage. This method has: a slag top-surface position measurement step of, with the position of a top surface of the molten iron having been measured in advance, continuously or intermittently measuring an arbitrary position in a top surface of the slag; a slag top-surface difference calculation step of calculating a slag thickness that is a 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 oxygen-containing 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.