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Liquid Desander – Secondary Accumulator Sizing (B-FSM065)

Liquid desander with secondary accumulator on automated skid

Many desander installations will require a secondary accumulator – also called the external accumulator. This is a sand holding vessel located directly below the desander vessel. The primary desander has a holding section, termed integral accumulator, so why is a secondary accumulator used and how do you size it?

A Secondary Accumulator is Used When…

  • The desander has an operating pressure >100 psig (6.9 barg)
  • When you want highly-controlled discharge of solids
  • To minimize gas/vapors flashing from the slurry
  • To minimize liquid loss from process

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%
  • Use level switch to automate discharge process
  • The quantity of solids reporting to ACC equals inlet concentration to Desander multiplied by separation (capture) efficiency
  • Volume of solids must be corrected for particle packing efficiency (0.62 average) – e.g. 100 liters of particulate solids packs at 161 liters effective volume

The next article will start the discussion on apex flux balancing. 

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