基于流体体积模型的放射性废树脂蒸汽重整流态化数值模拟分析

Numerical Simulation Fluidized Bed Steam Reforming of Radioactive Spent Resin in Volume of Fluid Model

放射性废树脂蒸汽重整反应器通常采用流化床结构。树脂在流化床中达到较好的流态化是保证反应持续、提高处理效率、实现树脂减容和核素包容的关键因素。为对流化床中树脂的流态化情况进行分析优化,建立了鼓泡流化床树脂蒸汽重整的计算模型,针对废树脂蒸汽重整中试流化床采用流体体积(volume of fluid,VOF)模型模拟流化床内树脂蒸汽多相流动状态。重点分析了不同流化操作气速下的床层压降、床高空隙率分布,获得了不同操作气速下的树脂流化状态。数值计算分析及后续测试结果表明,采用VOF模型可较好用于废树脂鼓泡流化床的计算模拟;操作气速增加,树脂的流化状态产生明显变化;当操作气速控制在0.7 m/s左右时,该中试流化床可达到最佳的流化状态。在此操作气速下开展了多组树脂蒸汽重整试验,最终获得的树脂重整平均减容倍数达到了6以上,在流化床内构件未发现树脂聚团,结焦现象,树脂在流化床形成了较好的流化状态。

The fluidized bed steam reforming is widely used technology to treat radioactive spent resins.Proper fluidization of spent resin in fluidized bed is the key to maintain the reaction,increase the reaction efficiency,implement volume reduction,and capture the nuclide.To analyze and optimize of the fluidization status,a simulation model of spent resin steam reforming in bubble fluidized bed was created.The multiphase flow field in the pilot fluidized bed for spent resin reforming was simulated in VOF(volume of fluid)model.The bed pressure drop and voidage distribution in vertical direction were analyzed by implementing different operation gas velocities and corresponding fluidization patterns were obtained.Results indicate that VOF model was proper to be used to simulate bubble fluidized bed for treating spent resins.The fluidization patterns of spent resin changed rapidly as the operation gas velocity increased,and the best at 0.7 m/s;the average reduction ratio of resin reforming was more than 6.No agglomeration and coking were found in the inner parts of the fluidized bed,achieving a good fluidization state.