Liquid Desander – Main Components (B-FSM074)
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.
- Rawlins, C.H., “Particle Transfer Between the Cyclone and Accumulator Sections of a Desander”, SPE Production & Operations, paper SPE-191147-PA, 2018.