Oxygen Injector Laval Nozzle Height Optimization
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Solution Overview
Problem
In metallurgical smelting units, existing oxygen injectors with Laval nozzles face challenges in optimizing the installation height and angle of attack to ensure effective decarburization and slag formation, particularly in reaching the molten metal surface with a coherent supersonic oxygen jet while avoiding contamination and splashing.
Innovation Solution
The method involves determining the optimal installation height of the Laval nozzle based on oxygen pressure, volume flow, and angle of attack, allowing the injector housing to protrude into the smelting unit, ensuring the oxygen jet remains supersonic until it reaches the melt surface, with a subsonic section extending to the surface to prevent splashing and ensure thorough mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the injector housing is positioned to project inwards into the melting unit, then the oxygen jet can reach the molten metal surface more effectively, but the risk of contamination and splashing increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the installation height of the Laval nozzle outlet opening based on oxygen pressure, volume flow rate, and angle of attack. This optimization ensures the oxygen jet maintains supersonic speed over the required distance while minimizing splashing and contamination, thus resolving the contradiction between productivity and harmful factors
Solution Approach 2:
The patent employs dynamics by allowing the injector housing to be positioned at an optimized angle of attack (α) relative to the vertical, rather than being fixed perpendicular to the side wall. This dynamic angular adjustment enables the oxygen jet to reach the molten metal surface effectively while controlling the jet's interaction with the melt to reduce splashing
2Stability of the object's composition
If the Laval nozzle is positioned farther from the melt surface, then contamination is reduced, but the oxygen jet loses supersonic speed before reaching the surface
Solution Approach 1:
The patent uses parameter changes by establishing a specific mathematical relationship for the installation height H based on oxygen pressure p, volume flow rate V̇, and angle of attack α. This ensures the oxygen jet maintains supersonic speed (Ma > 1) over the required distance while preventing jet dispersion and splashing, thus resolving the contradiction between jet coherence and harmful factors
3Ease of operation
If the injector is installed perpendicular to the side wall, then installation is simplified, but the oxygen jet path to the melt surface becomes excessively long
Solution Approach 1:
The patent applies dynamics by introducing an angle of attack α as a variable parameter, allowing the Laval nozzle to be inclined relative to the vertical rather than installed perpendicular to the side wall. This angular adjustment optimizes the oxygen jet path length to the melt surface while maintaining installation feasibility, resolving the contradiction between ease of operation and jet path length
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 enhances the decarburization efficiency and foamed slag formation by maintaining a coherent supersonic jet length, improving the treatment of molten metal while minimizing contamination and maintaining effective oxygen input.
Implementation Method 1
A Laval nozzle, which is used here as the primary nozzle. US Patent 2002001332A also describes an oxygen injector for a metallurgical vessel. Flow-optimized Laval nozzles are used for injectors and blow lances for defined applications in metallurgical plants
Implementation Method 2
Such speeds can be achieved with a Laval nozzle. An injector accelerates the oxygen-rich gas, usually pure oxygen, onto Supersonic speed (Ma > 1). The oxygen exits the Laval nozzle at approximately twice the speed of sound
Implementation Method 3
Such injectors are used to blow oxygen or an oxygen-rich gas onto or into a molten metal in the melting unit in order to decarburize the molten metal
Implementation Method 4
the integrated hot gas generator provides a coating jet of hot combustion gas that surrounds the cold oxygen jet, thereby increasing the length of the supersonic range
Data Source
Figure 1
AI summary
The invention relates to a metallurgical smelting unit (1) comprising at least one sidewall (2) having at least one injector opening (3), at least one injector housing (4) having an outlet opening (5), which housing is arranged on the injector opening (3) from outside the smelting unit (1) and partially projects inwards into the smelting unit (1), and at least one oxygen injector (7) comprising a Laval nozzle (6) and arranged in the injector housing (4). In order to improve treatment of a melt (10) in the metallurgical smelting unit (1), it is sufficient to provide an installation height (H) of an outlet opening (8) of the Laval nozzle (6) above a surface (9) of a melt (10) contained in the smelting unit (1) according to formula (I), wherein a, b, c, d, e and f are constant factors and p is the oxygen pressure in the inlet region of the Laval nozzle (6), V̇ is the oxygen volume flow through the Laval nozzle (6) and α is the setting angle of the Laval nozzle (6), and wherein the oxygen pressure in the inlet region of the Laval nozzle (6) is in the range 8 bar ≤ p≤ 12 bar, the oxygen volume flow through the Laval nozzle (6) is in the range 1400 Nm³/h ≤ ≤ 4400 Nm³/h and the setting angle (α) is in the range 40° ≤ α≤ 45°.