Kinetic Modeling on Nozzle Clogging During Steel Billet Continuous Casting

In the current paper, a kinetic model was developed to study the entrapment of inclusions in the molten steel flowing through a Submerged Entry Nozzle (SEN) during billet continuous casting process. The trajectory of inclusions was calculated by considering the drag force, lift force and gravitational force. The entrapment locations of inclusions on SEN wall were predicted. The effects of nozzle diameter, casting speed, billet dimension, and inclusion diameter on SEN clogging were quantitatively discussed. The results indicate the inclusions with diameter larger than 100 mu m are not able to be entrapped by the nozzle wall; and the entrapment probability will increase quickly with decreasing size of inclusions. The distribution of the entrapped inclusions along the nozzle length is non-uniform and the volume fraction of inclusions in the clogging materials should be considered in order to more precisely predict the accumulated weight of molten steel that can be poured before the nozzle is fully blocked by clogging. Under the conditions assumed: 150 mmx150 mm billet, 2.0 m/min casting speed, approximately 25 degrees C superheat, 1 m length of the SEN (Al2O3-C materials), 20 mu m inclusions diameter in a single size, 30 ppm TO and 40 mm nozzle diameters, the prediction shows that similar to 351 ton steel can be poured for the current billet continuous caster.