INTERTANKO International Association of Independent Tanker Owners Safe Transport, Cleaner Seas, Free Competition A Report upon Increased Effectiveness of CRUDE OIL WASHING (CRUCLEAN)

CRUCLEAN Project Objectives and Deliverables By use of the sludge data from CRUCOGSA examine the impact pressure from a COW machine during operation. Undertake alternative impact pressure measurements with differing nozzles and differing delivery pressures. Optimise COW Machine operational criteria to increase washing effectiveness and reduce the evolution of VOC from wash stock.

CRUCLEAN Project Example of Sludge Yield Stress

CRUCLEAN Project Measurement Record

CRUCLEAN Project Jet Appraisal

CRUCLEAN Project Observations – Operating Pressure Irrespective of nozzle size the operating pressures currently required (8 kg/cm 2 ) produce an impact pressure well in excess of the Yield Stress of typical sludge. Conclusion – operating pressure can be reduced.

CRUCLEAN Project Assessment of impact area The direct impact area for one cycle of an existing COW machine is approx 7.6%. (this excludes “splash zone” and therefore reduced impact pressure) By increasing nozzle size from the current 30 mm to 45 mm, the impact area is increased to 30.5% for one cycle of the machine.

CRUCLEAN Project Nozzle Flow Rates By increasing the flow rate into the cargo tank the final blend of sludge and COW stock will decrease to more flow/pumpable viscosities. Flow rate into the cargo tank is determined as a function of either delivery pressure and/or nozzle size.

CRUCLEAN Project Vapour Generation Vapour generation during washing has two primary consequences: –Loss of solvent that will dissolve sludge –Generate VOC gases that will be displaced to atmosphere during loading of next cargo. In order to decrease vapour generation a maximum operating pressure of 5 bar should be observed.

CRUCLEAN Project Interim Conclusions In order to increase effectiveness of a COW operation and reduce VOC emissions – the nozzle pressure should be reduced to below 5 bar (roughly kg/cm 2 ) and; – the COW machine nozzle should be increased to a size compatible with the tank size (jet reach)