Gas Processors Association Europe

Roger Dambach, Cryostar SAS, France

Turbines that remove enthalpy from a liquid and convert it into shaft power go back to the ancient Greco-Roman civilization. Today liquid turbines are applied to many applications. Even though the fundamentals of hydraulics have not changed a number of novel turbine concepts have appeared on the market such as the multistage reverse pump, the Euler turbine and the Variable Phase turbine.

The specific speed constitutes a reliable criterion for the selection of the most suitable liquid turbine for a given application. When this criterion is applied to the expansion of liquid hydrocarbon fluids such as LNG or Mixed Refrigerant it is shown that a radial inflow turbine has the wider range of applications than a radial outflow (Euler) or Pelton (Variable Phase) turbine. This is especially true when considering an expansion below the saturated liquid line because a two-phase flow will always yield higher specific speeds than a fully liquid phase at turbine discharge.