Reaction Chamber Gas Flow Control for Oxide Layer Uniformity
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Solution Overview
Problem
High strength steel grades with high silicon, manganese, and chromium content form an oxide layer during annealing, which hampers wetting and coating adhesion in galvanizing processes, and existing methods struggle to control oxide layer thickness uniformly across steel sheets of varying widths in continuous galvanizing lines.
Innovation Solution
A continuous annealing furnace with a reaction chamber that includes reactant openings at the top or bottom and inert gas openings on the lateral sides, allowing for controlled injection and extraction of gases to modulate the oxide layer formation, ensuring uniformity across the sheet width without mechanical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical systems with variable injection sections are used to control oxide layer formation, then oxide thickness uniformity can be adjusted, but system reliability deteriorates due to high temperature thermal expansion
Solution Approach 1:
The patent replaces mechanical variable injection sections with a gas flow control system. Instead of mechanically adjusting injection section positions (which fail under thermal expansion), the invention uses controllable gas flow rates through fixed openings to achieve oxide thickness uniformity. This substitution of mechanical adjustment with gas flow parameter control resolves the reliability issue while maintaining manufacturing precision.
Solution Approach 2:
The invention changes the control parameter from mechanical position to gas flow rate. By controlling the flow rate of oxidizing gas through fixed openings at different locations, the patent achieves oxide layer uniformity without relying on mechanical systems that are susceptible to thermal expansion. This parameter change enables reliable control in high temperature environments.
2Productivity
If oxidation is performed in a direct fired furnace with air excess, then oxidation efficiency improves, but control precision over oxide layer thickness deteriorates
Solution Approach 1:
The patent segments the oxidizing atmosphere supply into multiple separate openings distributed at different locations and heights within the reaction chamber. Each opening can be controlled independently, allowing precise control of oxide layer thickness while maintaining high oxidation efficiency. This segmentation replaces the single excess air supply approach with a distributed control system.
Solution Approach 2:
The invention applies local quality by providing oxidizing gas at specific locations (different heights and positions) rather than uniformly throughout the chamber. This localized gas supply enables precise control of oxide formation at different areas of the steel sheet, achieving both high efficiency and precise thickness control.
3Adaptability or versatility
If oxidation chamber is used occasionally for selective processing, then adaptability improves, but the need for frequent mechanical adjustment increases complexity
Solution Approach 1:
The patent eliminates mechanical adjustment systems by using controllable gas flow through fixed openings. This allows the oxidation chamber to be used occasionally for selective processing without requiring complex mechanical adjustments, reducing device complexity while maintaining adaptability.
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
The solution achieves a uniform oxide layer thickness with minimal edge-to-center variation, improving wetting and coating adhesion by precisely regulating inert gas and oxidant flows, reducing defects and overoxidation issues.
Implementation Method 1
the reaction chamber further includes inert gas openings supplied with an inert gas, the inert gas openings being located on lateral sides of the reaction chamber
Implementation Method 2
the reaction chamber including reactant openings supplied with a reactant, the reactant openings being located at a top or bottom of the reaction chamber
Implementation Method 3
High strength steel grades generally comprise high contents of elements like silicon, manganese and chromium (respectively typically between 0.5 and 2%; 1.5 and 6%, 0.3 and 1% in wt) making them difficult to coat because an oxide layer of those elements is formed during the annealing
Data Source
AI summary
A continuous annealing furnace for annealing steel strips has a reaction chamber wherein the steel strips are transported vertically, the reaction chamber having openings supplied with a reactant, also called reactant openings, located at the top or at the bottom of the reaction chamber, wherein the reaction chamber further has other openings supplied with an inert gas, also called inert gas openings, the inert gas openings being located on the lateral sides of the reaction chamber.