Parameters Analysis of Natural Gas Flows in Supersonic Separators

The supersonic separation is a new technology which can be used to condensate and separate water and heavy hydrocarbons from natural gas. In a supersonic separator, natural gas has an extremely short residence time to prevent hydrate problems and eliminates the need for chemicals and associated regeneration systems, providing an environmentally friendly facility for sustainable development. The dynamics parameters of natural gas in a supersonic separator and the effects of back pressure on the gas flows were numerically calculated using the standard k- model with real gas model. The results show that natural gas expands in the supersonic separator to supersonic velocities with resulting in low pressure (25 bar, from about 101 bar) and temperatures (-75 ˚C, from 30 ˚C), which causes the condensation and nucleation of some components. The higher back pressure induces the shock position shift forward from diffuser to nozzle. The shock goes into the diffuser when the pressure recovery efficiency is less than 0.7. If the pressure recovery efficiency is more than 0.8, the shock moves into the nozzle, resulting in the re-evaporation of the condensed components, which leads to the failure of the gas and liquid separation of this device.