Investigation on Nozzle Layout at Secondary Cooling Zone of Round Billet Continuous Casting

摘要

Nozzle layout has an important role in fulfilling the operational and production requirements. The nozzle arrangements in II zone of secondary cooling of a round billet continuous caster in a steel plant are simulated and the water flow density distribution at different range of air pressure and water pressure are analyzed. The result is, the spray zone of two adjacent nozzles which are mutual vertical to each other exist great wrap area, which cannot be eliminated when the air pressure and water pressure are decreased. According to solidification and heat transfer theory, with the steel performance parameter and the accurate boundary conditions, two dimensional heating transfer mathematical model was established, which based on finite difference method and the mind of setting slices on the slab along the casting direction. The surface temperature distribution of round billets in II zone of secondary cooling are computed and the temperature curve of different stagger angles of nozzle pairs in consecutive rows are compared. The results show that the temperature at the center of nozzle and spray wrap are all located at the wave trough of surface circumferential temperature curve, the temperature fluctuation of temperature curve that the stagger angle is 22.5° is smaller than when it is 45°. Eliminate the effects of non-uniform surface temperature distribution on the strand quality, thus reducing the defects in the finished product. With the increasingly development of economic, the requirement of round billet casting machine become more stringent, improving the round billet quality is essential for casting technique research. Equality of secondary cooling has great effect on the quality of round billet. Asymmetry cooling easily made the distortion, local cooling intension too strength, heat stress centralize, interior crack and surface crack. The factors that affect secondary cooling are cooling water distribution, nozzle layout, and nozzle type and so on [1, 2, 3, 4]. The present work aims to study the fitly nozzle layout in II zone of secondary cooling.