Inert Gas Jet Stabilization via Flame Envelope
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Solution Overview
Problem
The internal shroud method is ineffective for producing coherent jets of pure or high concentration inert gases, such as argon, due to the elimination of fuel combustion in the jet shear layer, and existing techniques fail to improve the refining of molten metal using inert gas jets in metallurgical furnaces.
Innovation Solution
A method involving a converging-diverging nozzle configuration where an inert gas stream is introduced with an oxygen stream and a hydrogen-containing fuel injected at specific locations within the nozzle, forming a combined stream that is accelerated to supersonic velocity without ignition, creating a flame envelope outside the nozzle to stabilize the inert gas jet and prevent velocity and concentration decay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the internal shroud method is used to form coherent jets, then mixing and dilution of molten steel is improved, but the method becomes ineffective for pure or high concentration inert gases due to elimination of fuel combustion in the jet shear layer
Solution Approach 1:
The patent introduces a dual-shroud system where an outer shroud provides fuel and oxygen for combustion in the shear layer, while an inner shroud delivers the inert gas (argon) to the molten steel. This intermediary fuel-oxygen shroud enables the internal shroud method to work with inert gases by providing the necessary combustion components externally, thus resolving the contradiction between maintaining mixing efficiency and achieving adaptability to inert gases.
2Productivity
If oxygen is used to form coherent jets, then mixing and dilution of carbon monoxide is improved, but oxidation of steel and undesirable by-products occur
Solution Approach 1:
The patent applies local quality by creating distinct zones with different gas compositions: the inner shroud delivers pure inert gas (argon) that contacts the molten steel to provide mixing without oxidation, while the outer shroud contains fuel and oxygen that combust in the shear layer to generate the coherent jet structure. This spatial separation of functions allows mixing efficiency to be maintained while eliminating harmful oxidation of the steel.
3Productivity
If external shroud technique is used with inert gas, then coherent jets can be formed, but device complexity increases due to external fuel passages and potential nozzle plugging
Solution Approach 1:
The patent employs a nested doll configuration where the inner shroud (delivering inert gas) is positioned inside the outer shroud (delivering fuel and oxygen). Both shrouds share a common nozzle exit, creating a compact integrated structure. This nesting eliminates the need for separate external fuel passages, reduces device complexity, and minimizes the risk of nozzle plugging by consolidating all gas delivery systems into a single integrated nozzle assembly.
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 the production of supersonic coherent jets of inert gases, minimizing oxidation of the metal and enhancing stirring action in the molten metal bath, while avoiding nozzle plugging and reducing the need for external fuel passages, thus improving the refining process and making the process more economical.
Implementation Method 1
a combined stream comprising the inert gas stream, the oxygen stream and the fuel stream is accelerated to a supersonic velocity within a diverging section of the nozzle
Implementation Method 2
The inert gas stream is introduced into an inlet section of the passageway at or above a critical pressure. As a result, a choked flow condition is established within a central throat section of the passageway
Implementation Method 3
auto-ignition of the flammable mixture through heat supplied by the heated furnace atmosphere
Implementation Method 4
combustion between the fuel and oxygen and results in the production of an argon coherent jet
Implementation Method 5
combustion between the fuel and oxygen in the shear (or mixing) layer to produce a coherent jet
Implementation Method 6
The structured jet is surrounded by a flame envelope that results from contact of the outer circumferential region of the structured jet with the heated furnace atmosphere
Data Source
AI summary
A method and apparatus for forming internally shrouded supersonic coherent jets comprising an inert gas, such as pure argon and argon/oxygen mixtures. This method and apparatus can be employed to produce low-carbon steels with a top lance in basic oxygen steelmaking.