Top-blowing lance nozzle with control gas spout for molten iron refining
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Solution Overview
Problem
Current oxygen-blowing refining methods for molten iron face challenges in simultaneously controlling the blowing rate and amount, leading to inefficiencies such as increased dust and decreased yield, and limitations in adjusting the blowing rate without compromising nozzle lifespan or efficiency.
Innovation Solution
A method involving a top-blowing lance with a nozzle design that includes a spout for a control gas, which is jetted into the nozzle to control the gas blowing rate independently of the main supply gas, allowing for a large variable range of gas blowing amounts and effective increase in blowing rate even under poor expansion conditions without using mechanically movable parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the blowing amount of oxygen-containing gas is increased to improve productivity, then the gas blowing rate becomes excessively high causing iron loss as dust and deposition, but reducing the blowing amount prevents excessive oxidation loss of iron
Solution Approach 1:
The invention changes the physical parameters of the gas flow by introducing control gas at the throat portion of the Laval nozzle. This creates a mixed flow that modifies the velocity distribution and reduces the excessive blowing rate at the bath surface, thereby preventing iron loss while maintaining adequate productivity
Solution Approach 2:
Control gas is introduced as an intermediary substance at the throat portion of the nozzle to mediate between the main oxygen flow and the bath surface. This control gas acts as a buffer that reduces the direct impact of high-velocity oxygen jet, preventing excessive iron oxidation and dust generation
2Stress or pressure
If the nozzle size is increased to reduce kinetic pressure at large gas blowing amount, then the blowing rate becomes excessively lowered when gas blowing amount is decreased
Solution Approach 1:
The invention introduces a dynamic control mechanism by adding control gas flow that can be adjusted independently of the main oxygen flow. This allows the system to adapt to varying operating conditions, maintaining optimal blowing rate across a wide range of gas blowing amounts without being constrained by fixed nozzle geometry
Solution Approach 2:
The gas flow is segmented into two independent controllable streams: the main oxygen-containing gas flow and the control gas flow. This segmentation allows independent control of each stream, enabling precise adjustment of the overall blowing rate and kinetic pressure characteristics
3Speed
If the lance height is adjusted to control blowing rate, then the service life of the lance is decreased due to erosion when height is low, but gas temperature inside converter is raised and refractory service life decreases when height is high
Solution Approach 1:
The invention replaces the mechanical adjustment method (changing lance height) with a fluid dynamic control method (introducing control gas at the nozzle throat). This substitution allows blowing rate control without mechanical movement, eliminating erosion issues associated with low lance height while avoiding excessive temperature rise from high lance height
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 enables effective control of the gas blowing rate regardless of the total gas blowing amount, increasing the blowing rate when it is small and maintaining efficiency under varying conditions, thereby improving productivity and reducing operational costs and dust generation.
Implementation Method 1
a control gas is jetted toward inside of the blowing nozzle for at least a part of a period of the oxygen-blowing refining from a spout arranged in a side face of the nozzle
Implementation Method 2
when a control gas is jetted toward inside of a blowing nozzle, a gas blowing rate at a nozzle outlet is increased
Data Source
AI summary
In a method for oxygen-blowing refining of molten iron, an oxygen-containing gas as a main supply gas is supplied from an inlet side of a blowing nozzle for the oxygen-containing gas passing through an outer shell of the top-blowing lance and blown from the blowing nozzle while a control gas is jetted toward inside of the blowing nozzle for at least part of a period of the oxygen-blowing refining from a spout arranged in a side face of the nozzle at a site where the cross-sectional area of the nozzle minimum takes the minimum in the axial direction of the nozzle or a neighborhood thereof so that at least part of the spout exists in each space formed by dividing into two portions by an arbitrary plane passing through a central axis of the nozzle.