Vapor-Liquid Separation at Supersonic Velocities

Abstract

When a gas mixture at high pressure is expanded to a lower pressure, autorefrigeration often causes some of the heavier components to liquefy. This paper presents a new method for separating components of a gas stream by incorporating isentropic expansion and subsequent inertial separation of the dispersed liquid phase formed. Supersonic velocity of the stream is attained upon expansion and is maintained during the vapor-liquid separation process. Liquid droplets are ejected through the permeable outer wall of a curved flow channel, effecting the phase separation. Pressure is recoverable in part, if the supersonic stream is decelerated in a diffuser after removal of the liquid phase. Design considerations of such a process and major parameters for obtaining and maintaining stable supersonic channel flow are discussed. An experimental unit designed for an 1800 psi natural gas feed stream has been tested and preliminary results are summarized.