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Liquid Desander – Main Components (B-FSM074)

B-FSM-074-Header
A two-inch (50 mm) desander liner being installed in a 150# vessel

This article is meant to capture and define all the main components of a liquid desander in one post. I’m a stickler for terminology, and this defines the component terms and their purpose.

As shown in the graphic below, there are four main components. A skid may have lots of other jewelry like instruments, valves, piping, skid frame, etc., but these are the four items core for desander proper operation.

Desander Vessel (ref post B-FSM-046 of 26-Jun-18)

  • The desander vessel is the pressure containment housing for the liners or insert. It is designed for process pressure and temperature, and should not be subject to erosion
  • Design the vessel of appropriate materials and codes compliant to rest of system
  • Typical code requirements are ASME Sec VIII Div 1 (150# to 900#) and NACE MR0175
  • The vessel is mainly carbon steel while the plates are always stainless steel
  • The bottom chamber of the vessel is the integral accumulator

Cyclone Liner or Insert (ref posts B-FSM-047 and -048 of 3-Jul and 10-Jul 2018)

  • The liner/insert performs the cyclonic separation duty and contains erosion
  • Liners are usually small diameter – from 1” (25 mm) to 3” (75 mm)
  • Liners should be made from erosion resistant material such as Stellite®, alumina, or silicon carbide
  • The liners are consumable and normally 1-2 year life

Isolation Valve (ref post B-FSM-064 of 04-Dec-18)

  • This is a single valve whose purpose is to discharge solids from the desander vessel and/or isolate the secondary accumulator
  • Recommended valve types are gate or rotating disc – must be straight, open path for solids to report to secondary accumulator
  • This valve is subject to erosion and should have hard facing on trim or ceramic internals

Secondary (or External) Accumulator (ref post B-FSM-065 of 11-Dec-18)

  • The secondary accumulator is a containment volume for the separated sand
  • Designed to same codes and materials as the desander vessel
  • Typically, 3:1 aspect ratio with 12 or 24 hour hold-up volume

The next article will discuss vessel and liner design. 

 

References:

  1. Rawlins, C.H., “Particle Transfer Between the Cyclone and Accumulator Sections of a Desander”, SPE Production & Operations, paper SPE-191147-PA, 2018.

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