Immersion Nozzle Segmented Outlet Design for Flow Balance
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Solution Overview
Problem
Conventional immersion nozzles for continuous casting of medium-thickness slabs experience imbalance in molten steel flow, leading to increased velocities and reverse flows that cause level fluctuations and asymmetric streams, affecting the quality and productivity of slabs during high-speed casting.
Innovation Solution
The immersion nozzle features a tubular body with a depressed lower section, narrow and broad sidewalls, and strategically positioned outlets with ridges and slits to balance exit-streams, reducing excessive velocities and level fluctuations by controlling the flow through the use of specific geometric configurations and outlet arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the throughput of cast slabs is increased to improve productivity, then productivity increases, but imbalance in exit-streams occurs leading to negative pressure and molten steel flowing into the nozzle
Solution Approach 1:
The single outlet is segmented into multiple outlets (first outlets in sidewalls and second outlets in bottom) with different orientations. This segmentation allows independent control of flow from each outlet, enabling balanced exit-streams even at high throughput by distributing the total flow through multiple pathways with different flow characteristics.
Solution Approach 2:
The first outlets and second outlets are designed with asymmetric orientations relative to the nozzle axis. The first outlets extend in a first direction while second outlets extend in a second direction different from the first direction. This asymmetric arrangement creates complementary flow patterns that balance each other, preventing negative pressure and flow reversal in any single outlet.
2Productivity
If larger amounts of exit-streams issue from lower portions of outlets, then throughput capacity increases, but imbalance increases causing excessive velocities and reverse flows
Solution Approach 1:
The outlet configuration transitions from a single-directional outlet to a multi-dimensional outlet arrangement. First outlets are positioned in sidewalls extending horizontally, while second outlets are positioned in the bottom extending downward at different angles. This multi-dimensional arrangement distributes flow in multiple spatial directions, balancing the velocity distribution and preventing excessive velocities in any single direction.
3Speed
If the velocity of molten steel streams impinging on narrow sidewalls increases, then throughput increases, but reverse flow velocities increase causing level fluctuation
Solution Approach 1:
The flow from second outlets acts as a counterbalancing force to the flow from first outlets. The second outlets discharge molten steel in directions that counteract the tendency of first outlet flows to create excessive reverse flows. This counterbalancing effect stabilizes the molten steel surface level by preventing asymmetric reverse flows that would otherwise cause fluctuation.
Data Source
AI summary
An immersion nozzle for continuous casting including a tubular body, the tubular body having at the upper end an inlet from which molten steel is introduced into a passage extending from the inlet downward inside the tubular body, the tubular body having a bottom and being depressed in cross section at least at a lower section, the lower section having two narrow sidewalls and two broad sidewalls, the narrow sidewalls having a pair of opposing first outlets communicating with the passage, the bottom having a pair of second outlets communicating with the passage. The lower section has ridges projecting into the passage respectively from the inner surfaces of the broad sidewalls between the pair of first outlets. The second outlets are arranged symmetrically about the axis of the tubular body such that the axes of the second outlets cross each other within the passage.