Multi-Point Rotating Gas Injection for Liquid Metal Stirring
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Solution Overview
Problem
Existing stirring methods for liquid metal in steelmaking vessels are inefficient, leading to the presence of dead zones and inadequate desulphurization, which affects the cleanliness and quality of the final steel product.
Innovation Solution
A stirring method using a device with at least two distinct injection points for inert gas and powder, one located in the bottom half of the liquid metal and the other near the liquid metal/slag interface, combined with rotation of the device, to enhance mass transfer and reduce dead zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas injection rate is increased to improve stirring efficiency, then mixing effectiveness improves, but metal splashes occur which are dangerous for operators and may damage equipment
Solution Approach 1:
The gas injection system is segmented into multiple injection points distributed around the vessel circumference rather than using a single injection point. This segmentation allows gas to be injected at multiple locations simultaneously, improving overall stirring efficiency while distributing the mechanical impact to prevent concentrated metal splashing at any single location.
Solution Approach 2:
The invention transitions from vertical gas injection (from above) to horizontal gas injection (from the side of the vessel). This dimensional change in injection direction fundamentally alters the flow pattern, creating more effective circulation while avoiding the upward splashing that occurs with vertical injection, thereby eliminating the safety hazard for operators.
2Productivity
If conventional gas injection is used, then some stirring is achieved, but dead zones remain on the vessel circumference farthest from injection points
Solution Approach 1:
Multiple gas injection points are positioned around the vessel circumference at different angular positions. This segmentation ensures that gas injection occurs at multiple locations simultaneously, creating multiple flow cells that collectively cover the entire liquid metal volume, including regions farthest from any single injection point, thereby eliminating dead zones.
Solution Approach 2:
The gas injection system is designed to serve multiple functions simultaneously: it provides stirring action, creates flow circulation, and ensures uniform composition throughout the liquid metal. The multi-point injection configuration allows a single system to achieve comprehensive mixing effectiveness across the entire vessel volume.
3Manufacturing precision
If desulphurization is performed efficiently, then sulphur content is reduced, but the process requires precise control of multiple parameters including oxygen content, slag composition, and stirring kinetics
Solution Approach 1:
The gas injection system is pre-configured with multiple injection points positioned at optimal locations around the vessel circumference. This preliminary arrangement of injection points creates an immediate and uniform stirring action from the start of the desulphurization process, eliminating the need for complex real-time adjustment of injection patterns or positions during the process.
Solution Approach 2:
The multi-point gas injection system automatically creates the desired flow patterns and stirring action without requiring active control or adjustment during the desulphurization process. The system self-regulates by utilizing the natural flow dynamics created by the fixed injection configuration, reducing the operational complexity of controlling oxygen content, slag composition, and stirring kinetics.
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 method improves desulphurization efficiency, reduces mixing time, and enhances the cleanliness of the liquid metal by promoting the formation of calcium sulphides and reducing the presence of inclusions, without creating metal splashes or open eyes that could be detrimental to operator safety and equipment.
Implementation Method 1
injection of an inert gas, such as nitrogen or argon, into the liquid metal
Implementation Method 2
enhance mass transfer and reduce dead zones
Implementation Method 3
combined with rotation of the device, to enhance mass transfer and reduce dead zones
Implementation Method 4
The main reaction for sulphur transfer which can occur at high temperature combines dissolved sulphur (S) in the liquid metal and calcium ions in the slag to form calcium sulphide which can be dissolved in the slag
Implementation Method 5
depending on its 'sulphide capacity': S + (CaO) = (CaS) + O
Data Source
Figure 1
Figure 2A~2B
Figure 3A~4C
AI summary
A method to stir liquid metal contained into a steelmaking vessel, said liquid metal being surrounded by a slag layer, the method comprising injection of a gas, optionally containing a powder, by at least two injection means located at at least two different injection points along the depth of the liquid metal, the first injection point being located in the bottom half of the liquid metal and the second injection point being located in the vicinity below the interface between liquid metal and slag layer, the gas injection being performed while rotating injection means along the vertical axis of the vessel. Associated device.