Title
Dewatering of Naphthenic Bitumen Froth
Date Issued
17 September 2020
Access level
metadata only access
Resource Type
journal article
Author(s)
Stammitti-Scarpone A.
Quraishi S.
Bhanot A.
Ng S.
Acosta E.
University of Toronto
Publisher(s)
American Chemical Society
Abstract
Bitumen froth is a water-in-bitumen emulsion (∼30 wt % water, 60 wt % bitumen, and 10 wt % of solids) stream obtained during the water-based extraction process of mined oil sands. The separation of water (to 2 wt % or less) and solids (to 0.5 wt % or less) from the froth is necessary to prevent corrosion, catalyst deactivation, and fouling in downstream processes. In naphthenic froth treatment (NFT), aromatic naphtha is added to reduce the density and viscosity of bitumen to aid in this separation, which often requires the addition of demulsifiers and centrifugation. This work looks at simulating the dewatering of froth using a bench-scale mixer and heptol 80/20 (80 vol % heptane; 20 vol % toluene) as a simulated naphtha solvent. Power dissipation during mixing, water contents, image analysis of micrographs, and acoustic spectroscopy were used to examine the dewatering process as a function of time for three froth samples with different compositions. Gravity drainage, in the absence of additives, led to a residual water content, after 2 h, ranging from 1.7 to 3.7 wt % for the three different samples, consistent with the typical residual water reported for these systems. Micrographs of the diluted froth show the eventual disappearance of large water drops and the prevalence of smaller emulsified drops (<10 μm) in the residual water. An examination of this residual water using acoustic spectroscopy showed that up to 0.8 wt % water is in the form of ∼0.3 μm submicron drops that cannot be removed by gravity or centrifugation. A dewatering model using an initial drop size distribution (DSD) of water drops also supports the existence of a substantial amount of submicron drops. A low-shear dewatering test suggests that most of this submicron water was in the froth before simulated froth treatment, formed potentially during bitumen extraction and transportation, prior to solvent dilution and dewatering. Cryo-SEM imaging further supports this hypothesis. Studies of water solubilization in toluene-asphaltene and toluene-naphthenic acid systems suggest that up to 0.5 wt % of this submicron water could be originated from water-asphaltene association. The presence of high solid contents in the froth correlated with high residual water and submicron water contents, pointing to the potential role of solids in the formation of submicron drops.
Start page
10688
End page
10704
Volume
34
Issue
9
Language
English
OCDE Knowledge area
Ingeniería del Petróleo, (combustibles, aceites), Energía, Combustibles Ingeniería química
Scopus EID
2-s2.0-85095445967
Source
Energy and Fuels
ISSN of the container
08870624
Sponsor(s)
The authors would like to thank Dr. Nathan Gerein (Earth and Atmospheric Sciences, University of Alberta) for performing and facilitating the analysis of cryo-SEM, Ms. Carla Gerein (Syncrude Scanning Electron Microscopist) for coordinating and providing insight into the analysis of the samples, Dr. Sujit Bhattacharya for suggesting the use of Cryo-SEM as an alternative method to determine DSDs, Mr. Sal Boccia of the Ontario Centre for Characterization of Advanced Materials (OCCAM) at the University of Toronto (UofT) for performing the Cryo-FIB-SEM work, Dr. Mehdi Nouraei and Mr. Rafael Perez of the LCFE lab at UofT for their help with the water solubilization studies at 80 °C, and Mr. Allen Yeung (Syncrude research) for all his support in preparing the samples for this study. The authors acknowledge the funding support from Syncrude Canada Ltd. and NSERC Collaborative and Research Development Grant CRDPJ 485476-15.
Sources of information: Directorio de Producción Científica Scopus