Abstract
This study investigated the effect of retrofitting and systematic upgrade of the Hydro-
cyclone De-oiler unit during produced water treatment. The internal orifice of the oil
reject cones attached to the end of the oil reject Liners was mechanically and
sequentially increased and the performance tested from 1mm up to 2.0mm; and then
dimensioned to a maximum of 3.0mm internal diameter. A single centrifugal pump
(maximum flow-rate of 199m3/hr (30,000 Barrels per Day) and a pressure of 10 -15 barg), was installed along a 6-inch produced water outlet spool of source production separator leading to the De-oiler. This was done in order to boost the operating pressure of the Hydro-cyclone De-Oiler unit to at least, the threshold limit of 5.7 bar-g. Keeping the operating pressure of the De-oiler below 4.2 bar-g, increasing the internal diameter of the oil reject Liner Cone orifice, followed by soaking and cleaning up of the clogged Liner tangential inlet with a 4:1 dilute hydrochloric acid, resulted in an increase in the reject oil production rate from 1.19 barrels per day/orifice to 4.45 barrels per day/orifice (a 374% increase). The introduction of the booster centrifugal pump increased the hydrocyclone operating pressure from an inlet pressure of about 3.5 bar-g to 7.0 bar-g, accelerated the outward acting centrifugal and G-forces to about 10 times its original value and increased the rising velocity of oil droplet size. The Hydro-cyclone De-oiler increased produced water throughput from the critical flow-rate of 77.0 m3
/hr to a maximum capacity of 201 m3 /hr. The main contribution of this research is the fact that produced water treatment unit Hydro-cyclone De-oiler oil reject flow-rate can actually be enhanced to about 177% with about 300% increase in initial oil reject cone orifice internal diameter; as long as the critical pressure drop ratio across the De-oiler or choked flow ratio is below 1.0 bar-g.