Simulation On Fluid Flow In Mold For Sha Steel Heavy Slab Continuous Casting

With the development of continuous casting technology, the high efficiency continuous casting is widely used in the actual production process. It means that the high quality slab is produced in the case of high casting speed and high sequence rate. The No.3 slab caster mold in Sha Steel was the object for investigation in the dissertation. The Submerged Entry Nozzle (SEN) and the production parameter were designed for 220mm, 250mm, 320mm mold respectively by using numerical simulation and the water model experiments.According to the parameters of 3# slab caster and the character of the mold in sha steel, 9 different SEN were disigned for the first step. Then, a water model was built for the mold by using the similarity principle. The liquid slag distribution, slag entrapment, surface fluctuation and bubble quantity beside narrow face were invested when the casting speed was maximum. For the each mold, two better nozzle were chosen for the further optimization. At last, the most suitable nozzle was designed by analysing the application of the two better nozzle when the casting speed was normal value.The results indicated that: the 5# nozzle should be the first choice for 220mm mold when the cross-section was small, and the 8# nozzle can be the choosen for big cross-section. The 8# nozzle should be the first choice for 250mm mold, and the 6# nozzle can be the second choice. For 320mm mold, when the casting speed less than 0.7m/min, the 6# nozzle should be the first choice, otherwise, the 9# nozzle is better.In the actual production process, the 5# nozzle was chosen for 220mm mold when the cross-section was small and the 6# nozzle was choosed for the big cross-section. For the 320mm mold, the 6# nozzle was used in casting process. All the above nozzles can guarantee the casting process and had no alarm of steel breaking out. The slag distribution was uniformly and the level fluctuation was in reason. The slabs had high qualities and the ratio of the crack was in the permissible limits.The results of bubble movement behavior showed that: with the casting speed increased, the dimension of the bubble decreased and the bubble dispersion from SEN to mold narrow face. Improvement of gas flowrate can increase the bubble dimension, but as gas pressure improved, the bubbles also moved to the narrow face. Blowing argon gas had much effects on the mold flow field and temperature field. The impact depth decreased and the cavity height improved with the gas flowrate increased. The improved surface velocity and temperature showed that the upper circulate of the steel was enhanced when blowing argon gas.