6.7.1 Centrifugal separation systems
This type of system has been used for many years but requires careful adjustment for maximum efficiency, as well as considerable maintenance. A schematic arrangement of the system is shown on Fig 2.62.
The principle of operation is that if a mixture of solids and fluids is centrifuged, they settle out radially according to their specific gravities. Dirty oil is delivered from the main oil tank into the purifier and is heated through a regenerative heater/cooler to the optimum temperature for centrifugal separation, around 75°C. The oil is delivered into the separator bowl and separates into its various densities under centrifugal force. A series of inverted cones collect the lighter oil (see Fig 2.63), and deliver it to the clean oil outlet. The water and acids are discharged through the outer drain: the solids accumulate in the bowl and are discharged at regular intervals. The clean hot oil is pumped through the regenerative heater/cooler, heating the incoming oil and is then returned to the main oil tank. The oil flow rate through the purifier is 10% of the oil inventory per hour.