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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.
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INTERTANKO International Association of Independent Tanker Owners Safe Transport, Cleaner Seas, Free Competition A Report upon Increased Effectiveness of CRUDE OIL WASHING (CRUCLEAN)
CRUCLEAN ProjectObjectives 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 ProjectObservations – Operating Pressure • Irrespective of nozzle size the operating pressures currently required (8 kg/cm2) produce an impact pressure well in excess of the Yield Stress of typical sludge. • Conclusion – operating pressure can be reduced.
CRUCLEAN ProjectAssessment 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 ProjectNozzle 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 ProjectVapour 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 ProjectInterim 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/cm2) and; • the COW machine nozzle should be increased to a size compatible with the tank size (jet reach)