Abstract
The desire to remain competitive and continuously produce high quality and high strength steel at the maximum production rate in continuous casting requires dynamic control over the spray cooling rate. Efficient and uniform heat removal without cracking or deforming the slab during spray cooling is critical. The challenge is to obtain accurate Heat Transfer Coefficient (HTC) on the slab surface as boundary condition for solidification calculations. Experiment based HTC correlations are limited to handful operating conditions and they might fail when changes occur. The current study presents a numerical model for spray cooling featuring the simulation of atomization and droplet impingement heat transfer in continuous casting. With the aid of high-performance computer, parametric studies were performed and the results were converted into mathematically simple HTC correlations as a function of essential operating parameters. Finally, a Graphic User Interface (GUI) was developed to facilitate future applications of the correlations. The HTC prediction is stored in the versatile comma-separated values (csv) format and it can be directly applied to solidification calculations. The proposed numerical methodology should benefit the steel industry by expediting the development process of HTC correlations and can further improve the accuracy of the existing casting control systems.
Highlights
More than 90% of semi-finished steel products are manufactured by continuous casting in the world today (Dantzig and Rappaz, 2016)
Heat Transfer Coefficient (HTC) on steel surface has been adopted as an indicator to quantify the spray cooling rate and has been served as one of the critical boundary conditions for solidification calculation
Experimental-based HTC correlations haven been widely used across the industry to predict HTC values under different operating conditions, but the development process is labor intense and can only cover a limited range of operating conditions
Summary
More than 90% of semi-finished steel products are manufactured by continuous casting in the world today (Dantzig and Rappaz, 2016). The refined molten steel undergone ladle treatment is transferred from the ladle furnace to a tundish, which serves as a reservoir and maintains the molten steel level during the ladle exchange. As the molten steel enters the rectangular mold, it solidifies into a thin solid shell against the water-cooled mold walls. This initial solidification process is referred to as the primary cooling process. A series of rolls located below the mold continuously withdraw the newly-formed thin shell, together with the enclosed molten steel, into the secondary cooling region where the semi-solidified steel is further cooled down by multiple rows of water sprays. Once the steel is completed solid, it can be cut into segments with varied lengths by oxygen torches for subsequent processing
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