Simultaneous removal of asphaltenes and water from water-in-bitumen emulsion: I. Fundamental development

Simultaneous removal of asphaltenes and water from a water-in-bitumen emulsion by adding light paraffinic solvents was investigated with a bench-scale unit. Asphaltene precipitation in bitumen, emulsion breaking and phase separation were found to be largely dependent on solvency and temperature. Increasing temperature facilitated the precipitation of asphaltenes in bitumen, and accelerated the separation of the light deasphalting oil (DAO)/solvent phase and the heavy asphaltenes/water phase. The removal of 98 +% asphaltenes and 99.9 +% water from the emulsion was achieved with the n-pentane/bitumen volumetric ratio of 3.0 in temperature range of 423-453 K. The interaction between asphaltene particles and water droplets is actually beneficial to the removal process. For process design and optimization, the operation pathway including two-step solvent injections at different temperature, the supercritical recovery of solvent from DAO stream and the solidification of asphaltenes by depressurization, as well as other important issues have been addressed. (C) 2008 Elsevier B.V. All rights reserved.