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Liquid Desander – Hydraulic Capacity, Turndown, and Performance for Liner Style Units (B-FSM061)

Desander liners packed between mounting plates in vessel

Putting together separation performance and hydraulic capacity, we can see the effect of flow rate (hydraulic capacity) turndown and performance. The flow rate (turndown) and performance are interlinked. A cyclone-based unit (desander) thus has a separation size that can be tuned to match changing condition.

We will first discuss the turndown and performance for liner style (i.e. multi-cone design) desanders. This is for liquid only flow. The chart below plots flow rate (produced water) versus pressure drop. It also shows the separation size (D98) experienced through this range of flow rates. Data is presented for two diameter desander liners – 1.5” (38 mm) and 3.0” (76 mm).

Hydraulic Capacity (per liner)

  • These are the recommended operating ranges (per liner). If more flow needs to be treated, then multiple liners are packed within the same vessel.
  • 38 mm (1.5”): 180 – 570 BPD
  • 76 mm (3.0”): 1120-3530 BPD

Turndown: Maintain within ΔP Range

  • Minimum ΔP: 5 psid – Needed to form/maintain vortex
  • Maximum ΔP: 50 psid – Capped to balance wear life
  • No shear maximum like deoilers

Separation Performance (D98)

  • 38 mm (1.5”): 10 microns at 50 psid and 20 microns at 5 psid
  • 76 mm (3.0”): 20 microns at 50 psid and 38 microns at 5 psid

Residence Time

  • Average 0.14-0.44 seconds for 1.5”-3.0” desanders
  • Allow 60 seconds after full flow for stable measurement (to ensure vessel completely liquid-filled)
  • Rapid response to slugging – separation is maintained within ΔP boundaries

The next article will discuss hydraulic capacity, turndown, and performance of insert style desanders. 

References

  1. Plitt, L.R., “A mathematical model of the hydrocyclone classifier”, CIM Bulletin, December, 1976, pp. 115-123.

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