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.

References:

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