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6. Three-Phase centrifuge – energy independent mobile unit Separation of oil, water and solids is a very important task during crude oil storage tanks and reservoirs cleaning. Traditionally it was achieved in two stages. On a first stage two phase decanter is used to separate solids and liquid than disc separator is separating oil and water. It is obvious that using one device in one continuous process is much more sufficient and preferable.6.1. Separation process Mixed stream of oil, water and solids enters centrifuge. Centrifugal force moves solids from the center to the bowl walls where it is accumulated. Helical screw transports solids to conical section where it is evacuated with screw conveyer. Simultaneously with solids oil and water are split under centrifugal force because of difference in their density. This process can be improved by heating and chemical treatment (demulsificator, flocculent, coagulant) of incoming stream. Water and oil are separately leaving centrifuge from the opposite side of solids. The centrifuge is composed of a cylindro-conical rotor put into rotation, through an electrical driving system, between two bearing blocks supported by a base frame. The rotor includes a decantation bowl, a scroll and a reducer, which allows the scroll to rotate slightly faster than the bowl.All mechanical organs are mounted on lubricated bearings.  Pic. 13 Centrifuge working diagram  |