This article will cover primary valve and accumulator size and selection for a multiphase desander from a process point of view. The mechanical design of valves will be covered in a future article.

Isolation (DBB) Valve Size

• The main operating valve lies between the desander and accumulator. At high pressure operation is it usually a double block and bleed configuration (DBB)
• Valve must be gate valve, with slab type preferred
• Valve flow path diameter must not be smaller than cyclone insert apex diameter (i.e. 10” insert has 3” apex, so valve flow path should be at least 75 mm)
• Flow path diameter may not be indicative from valve nominal size. Check valve drawing to ensure full port valve and diameter is sufficient.

Accumulator (ACC) Sizing

• Typically 2:1 or 3:1 aspect ratio (height:diameter)
• Total volume for reasonable collection time (8-12 hours at least)
• Recommended solids fill height ~75%
• The quantity of solids reporting to ACC equals inlet concentration to WHD multiplied by separation efficiency
• Volume of solids must be corrected for particle packing efficiency (0.62 average) – 100 liters of particulate solids packs at 161 liters effective volume

Multiphase desander application and operation will be covered in the next article.

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.