HEAT AND CHEMICAL TREATMENT OF MECHANICALLY RECOVERED W O EMULSIONS/

Nearly all crude oils and some heavier refined products form stable wa ter-in-oil (w/o) emulsions when spilled and weathered at sea. Breaking these emulsions and discarding the separated water allow more oil to be recovered and stored by OSRVs (Oil Spill Recovery Vessels) and make the handling of oily waste easier due to viscosity reduction. This st udy was conducted to determine whether a combination of heat and emuls ion breaker is more effective than either technique used alone. The re sults will be used to prepare guidelines for treatment of w/o emulsion s and planning of large-scale tests. A bench-scale laboratory study wa s carried out using emulsions prepared from different crude oil residu es (BCF-17, Alaskan North Slope and Bonny Light) and a Bunker C fuel o il/gas oil blend (IF-80). Tubes containing w/o emulsions, with or with out emulsion breaker added, were partially submerged in a water bath a t different temperatures to simulate the heating system of the recover ed oil tanks onboard the OSRVs. The effectiveness of the emulsion brea king was measured by recording settled water over a 24 h period. The r esults showed that: The stability of a w/o emulsion and its response t o heat and emulsion breaker is highly dependent on different character istics of the oil from which it is formed. Stable w/o emulsions that c an be slowly broken by heat alone were, in general, broken much more r apidly if emulsion breaker was added in addition to heat. The w/o emul sions formed from relatively paraffinic crude oil (e.g. ANS) exhibit f aster breaking rates than w/o emulsions formed from crude oils with hi gh asphaltene content, such as BCF-17. All w/o emulsions formed from t he crude oil residues could be broken by the application of moderate a mounts of heat. W/o emulsions produced from Bunker C/Diesel oil blend were not broken at all by relatively high heat inputs (up to 100 degre es C) and required both the addition off heat and emulsion breaker to obtain partially breaking. Copyright (C) 1996 Elsevier Science Ltd.