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Figure 7. Solid removal efficiency @ d50=10.6 µm

The experiments were conducted on a liner likely
to those used on real scale produced water plants
and with solid particles with same characteristics
of solids commonly separated by desander from
produced water.

The results from the models showed that:
1. Higher flow rate in each liner can be fed at
higher values of pressure drop: at higher pres-
sure drop, a lower number of liners are re-
quested for a specific separation;
2. Cut size is reduced at higher pressure drop
both in open and in closed underflow configu-
ration;
3. Lower cut sizes (d50) can be achieved in case
of open than in case of open underflow con-
figuration (at the same conditions of pressure
drop).

The developed model was successfully used
to design the desanding system installed in
an offshore produced water treatment plant.
The project involved the expansion and the re-
vamping of an existing oily water-treatment, in-
cluding injection system, installed on an offshore
platform in Congo in order to increase wastewater
treatment thus reducing final water discharge.
Figure 8. Pilot scale plant of solid - liquid hydrocyclone used for experimental campaign
The revamping included the replacement of two
exhisting deoiling hydrocyclones and the installa-
tion of a new desanding cyclone for solids removal
3
Conclusions having a normal capacity of 540 m /h.
A theoretical mathematical model was developed The desander was designed with the aim of re-
into a semi-empirical model thanks to the experi- moving the solids that could cause the erosion of
mental data achieved by tests conducted in factory the deoiling hydrocyclones downstream and was
on a pilot scale plant designed and manufactured installed on a compact skid in order to meet the
by Cannon Artes and the University of Salerno. platform’s needs of small footprint.

88 Impiantistica Italiana - Marzo-Aprile 2021