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Multiphase Desander – Particle Travel (B-FSM085)

Solid particle travel – from inlet through cyclone section to external accumulator – is shown graphically below.

Inlet Transition

  • The (cyclone insert) inlet section transitions the particles traveling through the inlet pipe to rotational flow, which imparts separation forces
  • Particles impact the upper cylinder then slide along insert inner wall entering into the cyclone flow pattern
  • The vortex finder prevents particles short-circuiting to the overflow stream


  • The body of the cyclone insert is comprised of the cone, cylinder, and apex
  • Heavy (large diameter) particles spin down inner wall of the cone-cylinder to report to the apex
  • Light (small diameter) particles are swept to overflow and are not captured
  • The apex is the concentration point for the captured particles
  • Upon reporting through the apex the captured particles fall by gravity through the integral collection section, valve assembly, and into the secondary accumulator

External (Secondary) Accumulator

  • The captured particles from the desander section descend by gravity into the accumulator
  • The settling sand displaces water in vessel, and the displaced water reports back to the desander section (post B-FSM-069)
  • No free oil reports to the accumulator as it has lighter density and cannot displace the water – this effect provides primary cleaning of the sand
  • The sand level in the accumulator is flat
  • The particle size distribution void spacing determines the packing density of the settled solids (post B-FSM-023)

The next article covers secondary accumulator operation for the multiphase desander.


  1. Rawlins, C.H. 2017. “Separating Solids First – Design and Operation of the Multiphase Desander”, paper 185658-MS presented at the SPE Western Regional Meeting, Bakersfield, CA, 23-27 April.
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