Numerical Study on N2 Removal from the N2/He Mixture by Supersonic Separation Technology

The application of supersonic separation technology in extracting helium from the N₂/He mixture is the primary innovation of this work, holding noteworthy promise. To begin with, a numerical model is constructed, incorporating governing equations for gas–liquid phase and the condensation model. The study reveals that nitrogen nonequilibrium condensation can be accomplished using the Laval nozzle, demonstrating the potential for N₂/He separation in the supersonic separator. Enhancing nitrogen nonequilibrium condensation within the Laval nozzle can be achieved by lowering the inlet temperature and raising the inlet pressure. Results show that nitrogen experiences intensive homogeneous nucleation over a short duration in the divergent section, leading to an ongoing rise in the nitrogen liquid mass fraction from 0% at the inlet to 10.5% at the outlet. This research verifies the viability of employing the Laval nozzle for nitrogen removal, carrying significant strategic implications for advancing nitrogen removal technologies in the recovery of helium from natural gas.