| Popis: |
In slab continuous-casting machines, the quality of the finished product mainly depends on the hydrodynamic behavior of the molten steel in the cavity of the continuous-casting mold, where the submerged entry nozzle is the central element. Recently, a nontraditional nozzle design was reported, where a solid barrier attached to the inner bottom wall of the nozzle divides its internal volume, particularly around the outlet ports. The solid barrier was named a flow divider. In this work, the effect of the flow divider is analyzed by comparing the performance of traditional nozzles with the performance of nozzles altered with the flow divider. The performance of the nozzles was evaluated experimentally, employing a scaled model of the mold section, using cold water as the working fluid. The shape of the nozzle outlet jets and the fluid flow pattern in the mold cavity were used to determine the performance of the nozzles. In addition, several factors affecting the process stability and the quality of the product were analyzed: the casting speed, the tilt of the nozzle outlet ports, and the injection of gas in the liquid stream entering the nozzle. The analysis showed that for the nozzles with the flow divider, (i) the outlet jets are narrow and symmetric, (ii) the symmetrical double-roll flow pattern in the mold cavity is obtained, (iii) the liquid-free surface is stable and has low distortions, and (iv) the flow divider neither increases the bubble breakage nor the coalescence between them. |
