Investigating the Effects of Inlet Conditions and Nozzle Geometry on the Performance of Supersonic Separator Used for Natural Gas Dehumidification

Abstract

Supersonic separators have found extensive applications in dehumidification of natural gases since 2003. Unlike previous studies, which have investigated the inlet conditions and nozzle geometry of supersonic separators for pure fluids, the present study employed a combination of momentum, heat, and mass transfer equations along with Virial equation of state (EOS) to inspect the effect of inlet conditions and nozzle geometry for methane-water systems. The simulation results were validated using several experimental data (borrowed from the literature) to ensure the capability of the current model. Afterward, the effects of various inlet parameters (P & T) and nozzle geometries (converging and diverging angles) were examined on the position of collection point and nucleation zone for separation of water vapor from a methane rich natural gas. The simulation results indicated that inlet gas temperature and pressure and diverging nozzle angle had severe effects on the condensation process inside supersonic separator, while the converging nozzle angle affects the inlet gas velocity and had minor effect on condensation process. For example, by increasing the 3S inlet pressure from 6 MPa to 10 MPa, the distance between throat and collection point reduced at least by half, whereas decreasing the inlet temperature from 300K to 285K, drastically decreased the same distance by fourth. The diverging nozzle angle effect approximately stood between the above two values.