Flat Immersion Nozzle Guide Plates for Stable Mold Bath Level
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Solution Overview
Problem
Existing flat immersion nozzles for continuous casting experience unstable molten steel flow and discharge flow, leading to significant fluctuations in the bath level in the mold, which can cause defects in slab quality and increase operational risks.
Innovation Solution
The immersion nozzle is designed with a straight-shaped tubular body and guide plates in the vicinity of discharge ports, with a specific ratio of guide plate distance to flow passage length, to stabilize the molten steel flow and optimize discharge flow, reducing fluctuations in the mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the immersion nozzle is designed with a rectangular flat cross-section and expanded width flow passage to accommodate thin slab casting, then the nozzle can be adapted to thin mold requirements, but the molten steel flow becomes disordered and turbulence increases
Solution Approach 1:
The flow passage is segmented into an upper expanded section and a lower restricted section by the flow passage restricting portion. This segmentation allows the nozzle to accommodate thin mold requirements while maintaining flow stability by creating a controlled flow pattern that prevents turbulence in the discharge region.
Solution Approach 2:
The flow passage restricting portion is strategically positioned to create a localized restriction in the lower region of the flow passage. This local quality change ensures that the molten steel flow remains stable and ordered at the discharge point, while the upper portion of the flow passage can still be expanded to match the thin mold dimensions.
2Productivity
If the molten steel flow passage width is expanded from inlet to discharge ports, then the nozzle can handle thin slab production requirements, but discharge flow turbulence increases and bath level fluctuation worsens
Solution Approach 1:
The flow passage is divided into two functional zones: an upper expanded zone that enables thin slab production and a lower restricted zone that ensures stable discharge flow. The flow passage restricting portion creates this segmentation, allowing the nozzle to simultaneously achieve high productivity for thin slabs while maintaining reliable discharge flow stability.
Solution Approach 2:
The flow passage restricting portion is positioned upstream in the lower region to preliminarily control and organize the molten steel flow before it reaches the discharge ports. This preliminary action ensures that the flow is stabilized and ordered before discharge, preventing turbulence and bath level fluctuations while maintaining the expanded width capability for thin slab production.
3Adaptability or versatility
If the immersion nozzle has a flat rectangular shape with long-side expanded flow passage, then it can be used for thin slab casting, but the flow pattern becomes disordered and slab quality defects increase
Solution Approach 1:
The flow passage is segmented into an upper expanded section for thin slab casting adaptability and a lower restricted section for flow control. This segmentation ensures that the molten steel flow remains ordered and stable, preventing the flow disorders that would otherwise lead to slab quality defects such as inclusion entrapment or uneven solidification.
Solution Approach 2:
The flow passage restricting portion creates a localized control zone in the lower region that ensures high manufacturing precision at the discharge point. This local quality improvement maintains ordered flow patterns essential for producing high-quality thin slabs, while the overall flat rectangular shape with expanded width preserves adaptability to thin slab casting requirements.
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
Stabilizes the molten steel flow and discharge flow, effectively reducing bath level fluctuations in the mold, thereby improving slab quality and safety during continuous casting.
Implementation Method 1
a pair of guide plates in the vicinity of the discharge ports, each formed to guide molten steel flowing through the flow passage toward a respective discharge port
Implementation Method 2
block contact of the molten steel with the atmosphere, thereby preventing oxidation thereof
Implementation Method 3
allow the flow of molten steel in the mold to be straightened, thereby preventing impurities such as slag or non-metal inclusions floating on the bath level of the molten steel from being entrained into the molten steel
Data Source
Figure 1(a)~1(d)
Figure 2~3
Figure 4(a)~4(g)
AI summary
The present invention is directed to a flat immersion nozzle capable of stabilizing a bath level in a mold, etc. The present invention provides an immersion nozzle X comprising a tubular body lhaving a bottom 2, an upper end serving as an inlet 11 of molten steel, and a molten steel flow passage 15 internally formed to extend downwardly from the inlet, at least a lower portion 13 of the tubular body 1 being formed such that an outer shape thereof and the molten steel flow passage 15 therein have a rectangular flat cross-section, the tubular body 1 having: two opposed sidewalls 131 each defining a short side of the rectangular flat cross-section of the lower portion13 and extending parallel to an up-down directional central axis 151 of the molten steel flow passage 15; and a pair of discharge ports 16 formed in respective lower ends of the short side-defining sidewalls 131 of the lower portion 13, in opposed relation, and communicated with the molten steel flow passage 15, wherein the immersion nozzle X comprises a pair of guide plates 3 in the vicinity of respective ones of the pair of discharge ports 16, each of the pair of guide plates 3 being formed to connect together two opposed sidewalls 132 each defining a long side of the rectangular flat cross-section of the lower portion 13 and to guide molten steel flowing through the molten steel flow passage 15, toward a respective one of the pair of discharger ports 16, wherein a ratio A/B is from 0.25 to 0.9, where A represents a shortest distance between the pair of guide plates 3 in a direction along the long side, and B represents a length of the molten steel flow passage 15 in the lower portion 13 in the direction along the long side.