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

Cone-Cylinder-Apex

• 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.

References

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.