Sustainable separation of Xe from the noble gas mixture of Ar, Kr, and Xe using cryogenic distillation and gas hydrates hybrid methods

Abstract

To date, cryogenic distillation remains the traditional method used for the separation of air components mainly oxygen and nitrogen, the trace components xenon, krypton, and argon are obtained as by-products. This method is known to be very energy-intensive as it involves the liquefaction of gas components at very low temperatures. In this work, thermally coupled distillation sequences and hydrate-hybrid processes were proposed as alternative separation processes to achieve the same effective separation of xenon with less energy consumption. The simulated alternative processes were compared based on energy savings and reduction of operating costs in the distillation section, and the overall xenon recovery relative to the conventional process. From all the simulated processes, a hydrate-hybrid process was found to be the best-performing configuration, achieving the desired separation of xenon with significant energy savings. Using this hybrid method, approximately, a 33% reduction of annual operating costs and 36% energy savings were achieved whilst maintaining a xenon system recovery of 99%, ensuring efficient use of the extracted air components. The use of gas hydrate promoters was recommended for the moderation of the pressure conditions for gas hydrate formation, to reduce overall operating costs. A simulation of the gas hydrate separation method, more comprehensive than the simplified approach taken in this study based on experimental data, was also recommended. This hybrid separation method contributes to sustainability by significantly reducing energy consumption and operating costs, which in turn mitigates greenhouse gas emissions and decreases dependence on nonrenewable energy sources.