A hybrid batch distillation/membrane process for high purification part 2: Removing of heavy impurities from xenon extracted from natural gas

Abstract

High-purity xenon of 6 N purity grade and higher is widely used in electronics, space, and medicine. A hybrid distillation/membrane process for the purification of xenon extracted from natural gas by gas hydrate crystallization is studied experimentally and via simulations. Membrane gas separation data for xenon-containing mixtures is measured for polysulfone membrane and polyetherimide/polyimide blend membrane. Parametric analysis and process optimization are performed in Aspen Plus Dynamics™ for a middle-vessel batch distillation column with an integrated hollow fiber membrane unit implemented via Aspen Custom Modeler™. Removal of higher- and lower-boiling impurities such as ethane, carbon dioxide, propane, methane, and krypton is considered to achieve 6 N and 9 N target purity grades. Hybrid distillation/membrane process flowsheets built with a multi-stream passive heat exchanger with either retentate or permeate being returned to the column are analysed. It is shown that the operating conditions and the configuration of the hybrid process with a membrane separation treatment of heavy impurities fraction can be tailored to achieve up to 30% increase in batch productivity for the considered case studies and improve xenon recovery reaching above 99.8% as compared to standalone batch distillation, which is especially critical for higher purity grades.