Separator Design for Use in High GVF Multiphase Flow

The requirement of bringing an outside coolant source to run through the seals of a multiphase pump has always been a costly endeavor. Using a separator to extract liquid from the exhaust of the pump to use as a coolant is often more expensive than providing an outside source of coolant. This research proposes a cost effective separator design which efficiently separates the liquid from gas, while maintaining a high enough residence time to remove any gas entrainment, and separates only the seal flush requirement by letting any excess liquids carryover with the gas.

Conventional multiphase separators operate by substantially decreasing the velocity of the mixture, which reduces the drag force put forth by the gasses and allows gravity to force the liquids downward. Gas-Liquid Cylindrical Cyclones (GLCCs) operate by increasing the velocity of the mixture, using radial force to separate liquids and gasses. This technique requires a smaller diameter vessel to achieve separation.

The separator in this research uses gravity as the separation force while maintaining a pipe diameter similar to the GLCC. This way, only standard pipe and pipe fittings are used. The effectiveness of this design is measured two ways. First, efficiency is studied at varying gas volume fractions (GVFs), velocities, pressures, and pipe diameters. Second, the length of air entrainment (LAE) is measured at the same varying conditions.

The efficiency and air entrainment studies provide design recommendations to accommodate seal flush requirements and size limitations. The following investigation also offers further areas of research to improve the understanding and modeling of using standard pipe and pipe fittings to create more effective design equations.