USE OF A GRAVITY TYPE OIL SEPARATOR FOR TANKER OPERATIONS

Abstract

ABSTRACT The need to control the oil content in ballast and tank cleaning discharges to meet increasingly stringent seawater pollution standards has led to the development of a gravity type separator capable of handling up to 300 tons/hour of oily ballast water. When properly handled these separators enable the tanker operator to clean tanks and process oily ballast with an oil content of up to 100% without fear of contamination of the seas. This continuous and automatic operation is unaffected by normal movements. The recovered oil is available for burning as fuel aboard ship, “load-on-top” or disposal ashore. Separators of this type have been in use on three 70,000 DWT ships, for periods of one to three years. On typical voyages a ship of this size can recover enough slop oil to provide one day or more of bunkers if the ship is equipped to burn the recovered oil. The ship's crew is trained to carry out analysis of the oil to determine if the oil can be burned onboard immediately following separation or must be treated to drop out salt and/or water prior to burning. Several typical ballast voyages using the separator will be discussed. The overboard discharge of water from the separator is analyzed to assure compliance with current pollution regulations and a means to shunt the overboard discharge into a holding tank is employed if the oil content is too high. Limitations and possible improvements of this type of separator will also be presented.