Steady-State simulation of cryogenic distillation used for helium isotope separation

Abstract

Helium-3 (3He) is an invaluable and scarce resource with applications in various scientific and industrial fields. It is typically found mixed with helium- 4(4He) in natural gas and nuclear off-gas, which is industrial source of helium. Therefore, separation of the helium isotope is necessary. Cryogenic distillation is a preferred method of separation due to its higher separation coefficient and processing capacity. In this study, a numerical steady-state simulation of cryogenic distillation column for helium isotope has been conducted using programming. The mathematical model for the equilibrium-state cryogenic distillation process was established and solutions of the thermodynamic formulation was proposed. The simulation provided the distribution of 3He and 4He along each distillation column as well as the profiles of temperature and flow rates along the column, based on the designed specifications including the composition of the feeding mixture, feed flow rate and pressure. The required heat duty of the condenser and reboiler was also calculated, and the column dimensions were estimated. Besides, we have studied the effects of the reflux ratio and feed concentration of 3He on the final isotopic contents of the top and bottom products. The results demonstrated that the distillation simulation could provide crucial theoretical support for the smooth execution of future laboratory experiments.