Hydrocyclone separators, sometimes called enhanced gravity separators, use centrifugal force to remove oil droplets from oily water.

The hydrocyclone separator consist of the following four sections: a cylindrical swirl chamber, a concentric reducing section, a fine tapered section, and a cylindrical tail section. Oily water enters the cylindrical swirl chamber through a tangential inlet, creating a high-velocity vortex with a reverse-flowing central core.

The fluid accelerates as it flows through the concentric reducing section and the fine tapered section. The fluid then continues at a constant rate through the cylindrical tail section. Larger oil droplets are separated out from the fluid in the fine tapered section, while smaller droplets are removed in the tail section.

Centripetal forces cause the lighter-density droplets to move toward the lowpressure central core, where axial reverse flow occurs. The oil is removed through a small-diameter reject port located in the head of the hydrocyclone separator.

Clean water is removed through the downstream outlet.

Advantages of static hydrocyclone separators include:

  • They have no moving parts (thus, minimum maintenance and operator attention is required)
  • Their compact design reduces weight and space requirements when compared to those of a flotation unit
  • They are insensitive to motion (thus, they are suitable for floating facilities)
  • Their modular design allows easy addition of capacity
  • They offer lower operating costs when compared to flotation units, if inlet pressure is available.