Separation of Emulsions with Fibrous Filter-Coalescers

During froth treatment, a water-in-diluted bitumen emulsion is obtained. The emulsified water contains chloride ions that form hydrochloric acid in downstream oil processing, leading to catalyst deactivation and equipment corrosion. Emulsified water, drops smaller than 10 μm, cannot be effectively removed by gravity settling and centrifugation to below 2 wt %. In this work, a filter-coalescer was used to promote the coalescence and separation of water-in-bitumen emulsion. The larger water drops (>300 μm) exiting the coalescer undergo gravity settling, reducing the water content in diluted bitumen emulsions to values lower than 0.1 vol %. The performance of the coalescer was interpreted via the colloid filtration theory of Rajagopalan and Tien (RT), improved in this work with a coalescence probability (CP) prefactor. This new RTCP framework was able to reproduce the experimental data, allowing its potential use as a predictive model for emulsion filtration and the operation of filter-coalescers. A capillary number analysis was used to account for the detachment of coalesced drops and interpret the drop sizes with different superficial velocities and bed porosities.