多管真空循环脱气系统循环流动模型

MODELING OF CIRCULATING FLOW IN RH DEGASSING VESSEL WATER MODEL DESIGNED FOR TWO-AND MULTI-LEG OPERATIONS

发展一个分析两管和多管真空循环脱气系统的循环流动特征数学模型．采用空间变密度的均相流模型模拟上升管中的气液两相流动，使用纯液相和气液两相之间的密度差作为系统中循环流动的驱动力，上升管中的气相体积分率是通过移植和修正喷气搅拌钢包含气率模型获得．利用空度技术处理包括钢包、真空室、上升管和下降管在内的复杂几何系统的流场计算．使用本模型对两管和多管真空循环脱气系统在喷气量为 ５－３５ Ｌ／ｍｉｎ情况下进行数值模拟．计算的下降管出口处的速度分布与文献中的测量值很接近．分析计算结果表明，多管系统中的速度分布比两管系统的速度分布均匀，即在下降管面积相同的情况下，多管系统的循环流量大于两管系统的循环流量．示踪剂扩散的模拟结果亦清楚展示了两种系统中流动特征的差别．

A mathematical model has been developed to analyze the circulating flow characteristics in RH degassing vessel designed for two- and multi- leg system. The homogeneous model with the spatially variable density was used to simulate gas-liquid flow in up-legs, The difference of density between pure liquid and gas-liquid was considered to be a driving force of circulation flow. The volume fraction of gas was obtained by modifying the gas plume model of the stirred ladle. The complicated geometry including ladle, vacuum, up legs, and down leg was considered by incorporation of blockage technique. Numerical calculations of the circulating flow have been conducted for the water model of RH degassing vessel with two- and multi-legs with the air flow rates from 5 to 35 L/min. Computed velocities at the exit of down-leg agree well with the observed data available in the literature. The momentum transport in RH degassing vessel with multi- leg will be larger than that with two-leg. This is justified based on the fact that the velocities in RH degassing vessel with multi- leg tend to be uniform, i.e. the mean velocity of bulk in a ladle is remarkably larger than that in two-legs. Simulated transient concentration profile of the tracer from top surface to interior shows clearly the difference of flow characteristics between two- and multi-leg RH degassing vessels.