Fluid Flow and Inclusion Motion in Continuous Casting Strands: Water Model, Numerical Simulation and Industry Measurement

摘要

Increasing the productivity and improving the product quality are permanent requirements concerning the continuous casting process. Plant observations have found that many serious quality problems, including inclusion entrapment, are directly associated with the flow pattern in the mold. Thus design and control of the fluid flow pattern in the continuous casting mold to remove inclusions is of crucial importance to the steel industry. The flow pattern in the mold can be controlled by many variables, including the nozzle and mold geometry, submergence depth, steel flow rate, argon injection rate, electromagnetic stirring, and flux layer properties. Nozzle technology is an easy and inexpensive way to optimize the fluid flow in the mold. New techniques involving the Submergence Entry Nozzle (SEN) to improve the fluid flow pattern and inclusion removal includes swirl nozzle technique, step nozzle technique, multiports nozzle, and oval offset bore throttle plate. The fluid flow in the continuous casting mold can be investigated by mathematical modeling, physical modeling, or industrial trials. Mathematical modeling is an effective, inexpensive tool to get information that cannot be directly measured in the steel. In the current study, industrial measurement of inclusions and total oxygen in a Low Carbon Al-killed steel are measured. A water model experiments are executed to investigate the level fluctuation with different gas flow rate, different casting speed, etc. Then the steady flow in the SEN and the strand of the continuous caster is simulated with a 3-D finite-difference computational model using the standard k-ε turbulence model in Fluent. Inclusion trajectories are calculated by integrating each local velocity, considering its drag and buoyancy forces. A "random walk" model is used to incorporate the effect of turbulent fluctuations on the particle motion.