Upper Nozzle Bore Shape and Gas Injection for Steel Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The adhesion of inclusions and metals to the wall surface of an upper nozzle in a tundish, leading to flow passage narrowing and potential clogging, remains a challenge despite existing techniques, including gas injection, due to variations in molten steel and gas flow.
Innovation Solution
The method involves an upper nozzle with a bore shape defined by specific cross-sectional curves to minimize energy loss and turbulence, combined with a gas injection function where the gas rate is limited to 4.3% or less of the molten steel flow rate, and gas is evenly distributed across the nozzle height, preventing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gas injection function is added to suppress adhesion, then adhesion suppression is improved, but flow variation occurs causing clogging
Solution Approach 1:
The patent optimizes the bore shape parameters (curvature radius, taper angle) and gas injection parameters (gas rate RG, flow distribution) to achieve stable flow. Specifically, the bore cross-sectional shape is defined by precise mathematical formulas with controlled curvature, and the gas rate is limited to RG≤4.3×VL to prevent flow instability while maintaining adhesion suppression.
Solution Approach 2:
The patent applies different gas injection rates to different regions of the bore wall surface. The gas-permeable refractory member is designed with localized gas permeability characteristics, allowing differential gas injection along the bore height to stabilize flow patterns and prevent clogging while suppressing adhesion in critical regions.
2Loss of energy
If bore shape is optimized for smooth flow, then energy loss is reduced, but adhesion still occurs with gas injection
Solution Approach 1:
The upper nozzle employs a composite structure combining a gas-permeable refractory member with specific bore geometry. The refractory material provides gas permeability while the precisely controlled bore shape (defined by mathematical formulas with specific curvature radii and taper angles) ensures smooth flow, achieving both low energy loss and adhesion suppression through the composite design.
Solution Approach 2:
The patent utilizes gas injection through the porous refractory member to create a fluid dynamic environment that suppresses adhesion. The injected gas modifies the flow characteristics of molten steel along the bore wall, preventing inclusion and metal adhesion while the optimized bore shape maintains efficient flow with minimal energy loss.
3Object-affected harmful factors
If gas rate is increased to suppress adhesion, then adhesion suppression is improved, but flow passage becomes clogged
Solution Approach 1:
The patent establishes a precise mathematical relationship for the gas rate parameter, limiting it to RG≤4.3×VL where VL is the molten steel flow velocity. This parameter optimization ensures sufficient gas injection to suppress adhesion while preventing excessive gas flow that would cause clogging and interrupt casting operations.
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
This approach effectively suppresses adhesion, ensuring stable continuous casting operations, extending nozzle life, and improving productivity by preventing clogging and maintaining high-quality cast slabs.
Implementation Method 1
the insert nozzle comprises a porous refractory member (gas-permeable refractory member) defining the bore, thereby fulfilling a function of injecting inert gas into the bore
Implementation Method 2
a bore having a shape capable of creating a less energy loss or smooth (constant) molten steel flow to suppress the occurrence of the adhesion
Data Source
AI summary
With a view to adding, to an upper nozzle formed with a bore having a shape capable of creating a less energy loss or smooth (constant) molten steel flow to suppress the occurrence of adhesion of inclusions and metals in molten steel, a gas injection function to thereby further suppress the occurrence of the adhesion, the present invention provides a method of using an upper nozzle configured to have a cross-sectional shape of a wall surface defining the bore, taken along an axis of the bore, comprising a curve represented by the following formula: log(r (z))=(1/n)×log((H+L)/(H+z))+log(r (L)) (n=1.5 to 6), where: L is a length of the upper nozzle; H is a calculational hydrostatic head height; and r (z) is an inner radius of the bore at a position downwardly away from an upper edge of the bore by a distance z. The method comprises using the upper nozzle in such a manner as to satisfy the following relationship: RG≦4.3×VL, where RG is a gas rate defined as a volume ratio of a flow rate QG (Nl/s) of injection gas to a flow rate QL (l/s) of molten steel flowing through the bore (RG=(QG/QL)×100(%)), and VL is a flow speed of the molten steel at a lower edge of the upper nozzle.