Flat Immersion Nozzle Central Protrusion Flow Stabilization
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Solution Overview
Problem
The existing immersion nozzles for continuous casting, particularly those used for thin and medium thickness slabs, face challenges in stabilizing the flow of molten steel, leading to fluctuations in the molten steel surface, oxidation, and poor quality cast pieces due to disturbances in the flow and uneven temperature distribution.
Innovation Solution
A flat immersion nozzle design featuring a central protrusion portion with a specific ratio of length to width and thickness, which is symmetrically disposed and slants downward towards the discharge port, along with optional upper protrusion portions, to gently control the flow direction and rate, preventing complete separation of the flow and maintaining a balanced distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the width of the inner hole is expanded from the molten steel inlet to the discharge port in a flat immersion nozzle, then the nozzle can accommodate thin and medium thickness slabs, but the flow of molten steel becomes readily disturbed causing fluctuation in liquid surface and poor quality
Solution Approach 1:
The inner hole is segmented into multiple sections with different width characteristics. The upper section has a smaller width to maintain flow stability, while the lower section has a larger width to accommodate thin and medium thickness slabs. This segmentation allows the nozzle to adapt to different slab thicknesses while preventing flow disturbance and liquid surface fluctuation.
2Adaptability or versatility
If the immersion nozzle is made flat with discharge port in side wall, then it can respond to thin mold for continuous casting, but the flow disturbance causes oxidation and engulfment of impurities
Solution Approach 1:
The nozzle is designed as a flat structure with the discharge port positioned in the side wall to match thin molds. The inner hole width varies along the length, being smaller at the upper section and larger at the lower section near the discharge port. This segmentation maintains stable laminar flow throughout the nozzle, preventing flow disturbance that would cause oxidation and impurity engulfment while still accommodating thin mold geometries.
3Adaptability or versatility
If the immersion nozzle has a flat shape with expanded inner hole width, then it can be used for thin slab casting, but the discharging flow fluctuation leads to poor quality cast pieces
Solution Approach 1:
The inner hole is divided into upper and lower sections with different width characteristics. The upper section maintains a smaller width to ensure stable flow and prevent fluctuation, while the lower section has a larger width to accommodate thin slabs. This segmented design enables the nozzle to be used for thin slab casting while maintaining manufacturing precision and producing high quality cast pieces without flow-induced defects.
Data Source
AI summary
A flat immersion nozzle stabilizes the discharging flow of molten steel thereby stabilizing the molten steel surface in a mold, namely, decreasing the fluctuation thereof. In the immersion nozzle having a flat shape in which a width Wn of an inner hole is greater than a thickness Tn of the inner hole, a central protrusion portion (1) is disposed in a center section of a wall surface in a width direction of a flat section. Wp/Wn, a ratio of a length Wp of the central protrusion portion in the width direction to Wn, is 0.2 or more and 0.7 or less. The central protrusion portion (1) is disposed symmetrically as a pair; and a total length Tp in the thickness direction of the pair of the central protrusion portions is 0.15 or more and 0.75 or less of Tn.