Optimisation study of a supersonic separator considering nonequilibrium condensation behaviour

Abstract

The supersonic separation offers an opportunity for natural gas processing. The problem is that the phase change of water vapour in the supersonic flow is not fully understood in the presence of shock waves in a supersonic separator. This study aims to evaluate the performance of the supersonic separation with the phase change process and shock waves. The condensing flow model is developed to accurately predict the energy conversion within the supersonic separator. The computational results show that the single-phase flow model over-estimates the vapour expansions by 12.43% higher Mach number than the condensing flow model. The liquid fraction of 8.2% is predicted by the condensing flow model during the phase change process in supersonic separators. The supersonic separator is optimised via combining the diverging part of the supersonic nozzle and constant cyclonic separation tube as a long diverging part of the newly designed nozzle. The optimised supersonic separator reduces the energy loss by eliminating the oblique and expansion waves in the newly designed nozzle, which improves the energy efficiency for natural gas processing.