Prediction of vapor-liquid equilibrium data of uranium hexafluoride and fluoride and simulation of distillation process
The purification of uranium hexafluoride by distillation technology is an important part of the uranium conversion process.The simulation of the distillation process can provide key support for process design and operation optimization.However,due to the lack of vapor-liquid equilibrium and physical properties data for uranium hexafluoride and fluoride,modelling and simulating the purification process of uranium hexafluoride became challenging.To address this issue,we utilized COSMOtherm and Turbomole software to predict vapor-liquid equilibrium data for UF6-TiF4 binary systems.We indirectly verified the accuracy of the COSMO-RS model by predicting known experimental data on vapor-liquid equilibrium for WF6-UF6 binary system.Additionally,Aspen Plus software's property constant estimation system was employed to estimate missing physical properties such as infinitely dilute aqueous Gibbs generating energy.The UF6 saturated vapor pressure experimental data and simulated values in the literature were compared,and the relative error was within 1.76%.Based on experimental data and predicted vapor-liquid phase equilibrium data in the literature,Aspen Plus software was used to regress the binary interaction parameters of the NRTL model.For separating uranium hexafluoride from fluoride,two purification schemes were designed:one involving direct separation sequence and another involving indirect separation sequence.Sensitivity analysis was conducted to optimize key parameters including plate number,feed position,and reflux ratio to minimize total annual cost(TAC)while maintaining desired purity levels in UF6 product output streams.The results indicated that TAC was lower for the indirect separation sequence purification scheme.
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维普
