Multiphase Desander – Particle Travel (B-FSM085)
Solid particle travel – from inlet through cyclone section to external accumulator – is shown graphically below.
- 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.
- 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.