Annular Weir Flow Control in Continuous Casting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing weirs in continuous casting apparatuses fail to effectively control high-speed flows of molten metal, leading to short circuiting and slag entrainment, which hampers the separation of non-metal inclusions and can damage equipment.
Innovation Solution
An annular weir with a cavity having a circular transverse section, featuring an inner protrusion and specific diameter and height ratios, is fixed at the bottom of a tundish under a ladle nozzle, slowing opposing streams and increasing the time for molten metal to reach immersion nozzles, thereby promoting inclusion separation and minimizing slag entrainment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional weirs are used to prevent short circuiting, then the paths of molten steel are lengthened, but high-speed flows are not controlled and slag entrainment occurs
Solution Approach 1:
The weir structure is segmented into multiple functional zones: an impact zone for receiving molten steel, a rebound zone for controlling upward flow, and a diffusion zone for slowing streams. This segmentation allows each zone to address specific flow control requirements, preventing both short circuiting and slag entrainment simultaneously.
Solution Approach 2:
The patent optimizes geometric parameters including the weir height (H) set at 1/10 to 1/5 of bath height, cavity diameter (D) at 1/3 to 1/2 of bath diameter, and rounded corner radius (R) at 1/10 to 1/5 of cavity diameter. These parameter changes transform the weir from a simple barrier into a flow control device that manages both path lengthening and speed reduction.
2Duration of action of moving object
If weirs are disposed to lengthen paths for inclusion separation, then floatation time increases, but high-speed streams toward side walls may still occur
Solution Approach 1:
The cavity structure acts as an intermediary between the incoming molten steel and the tundish interior. It receives the high-speed stream, controls the rebound, and releases a diffused flow that achieves both extended path length and reduced speed, preventing side wall impacts while maintaining long residence time for inclusion separation.
Solution Approach 2:
The invention introduces a vertical dimension to flow control through the cavity depth and rebound mechanism. By utilizing upward rebound followed by downward diffusion, the flow path extends in multiple dimensions, increasing residence time without maintaining high speeds in any single direction.
3Reliability
If upward streams are allowed to rebound without control, then short circuiting to immersion nozzles may occur, but controlled rebound increases inclusion separation time
Solution Approach 1:
The weir structure performs preliminary flow control at the point of molten steel entry. By immediately managing the rebound through the cavity design with optimized dimensions and rounded corners, the system prevents subsequent short circuiting while establishing a controlled flow pattern that extends residence time for inclusion separation throughout the tundish.
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 annular weir effectively controls high-speed flows, reduces slag entrainment, and improves the quality of cast products by extending the time for non-metal inclusions to float, while being cost-effectively manufactured and minimizing structural disadvantages.
Implementation Method 1
the stream of molten metal, which is directed by the long nozzle into the cavity of the annular weir, impacts the bottom of the tundish or the annular weir, and rebounds upward
Implementation Method 2
the inner protrusion tightens up an upward stream and the upward stream interferes a downward stream from the long nozzle. This configuration slows the opposing upward and downward streams each other
Implementation Method 3
promotes float and separation of the non-metal inclusions in the molten metal
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
OBJECT To provide a weir capable of controlling high speed flows as well as preventing short circuiting of molten metal. MEANS OF REALIZING THE OBJECT An annular weir 11 is fixed at a bottom of a tundish and just under a long nozzle 15 of a ladle in a continuous casting apparatus. The annular weir 11 includes a cavity 13 which has a substantially circular shaped transverse section. The cavity 13 includes: an upper side opening configured to receive a stream of molten metal from an upper side through the long nozzle 15; an inner protrusion 13d which is annular in shape and which extends toward an inner side from an upper end of an inner wall of the cavity 13; a first space 13a on an inner side of the inner protrusion 13d; and a second space 13b which communicates with the first space 13a and which is on a lower side of the first space 13a.