Liquid-Phase Compositions from Vapor-Phase Analyses. II. Adaptation of the Prausnitz Program to UF sub 6 and Some of Its Potential Impurities

摘要

There is an economic incentive to use vapor-phase samples of UF sub 6 for determining the concentration of impurities in cylinders of UF sub 6 rather than using liquid-phase samples, as has been done in the past. Calculation of liquid-phase concentrations from vapor-phase sample analyses would rely on a thermodynamic vapor-liquid equilibrium model. J.M. Prausnitz and coworkers have developed a suitable model based on the Hayden-O'Connell equation of state to account for vapor-phase non-idealities. This model has been implemented and tested. Molecular parameters for UF sub 6 and common impurities have been obtained, and preliminary calculations have been made for representative impurity concentrations. The results of these calculations are compared with those of earlier calculations based on the Redlich-Kwong equation of state and Scatchard-Hildebrand regular solution theory. With the Prausnitz model, efforts to regress binary interaction parameters and vapor-phase association parameters from available data are continuing. Recommendations are presented to sample and to analyze both vapor and liquid phases from UF sub 6 cylinders so that the model may be validated. After the remaining parameters have been obtained and after the model has been validated, the Prausnitz model should provide a sound basis for determining liquid-phase composition from vapor-phase sample analyses of UF sub 6 and its common impurities. 14 refs., 1 fig., 20 tabs. (ERA citation 10:028188)