1542
Energy & Fuels 2005, 19, 1542-1547
Monitoring the Settling of Water-Solids-Asphaltenes Aggregates Using In-Line Probe Coupled with a Near-Infrared Spectrophotometer Yicheng Long and Tadeusz Dabros* CANMET Energy Technology Centre-Devon, Natural Resources Canada, #1 Oil Patch Drive, Devon, Alberta, Canada T9G 1A8 Received May 3, 2004
Zone settling develops when bitumen emulsions are treated with aliphatic solvents at solventto-bitumen (S/B) ratios that are higher than a critical value. Near-infrared (NIR) spectroscopy is used in combination with an in-line fiber-optic diffuse transflectance probe to monitor the settling of the water-solids-asphaltenes aggregates in solvent-diluted bitumen. NIR spectra are obtained via the probe that is inserted in the settler, and the settling rate is calculated using the acquired NIR spectroscopic data. It was observed that a lighter aliphatic solvent leads to a much higher settling rate than a heavier aliphatic solvent at the same S/B dilution ratio. For the same solvent, a higher dilution ratio results in a higher settling rate.
1. Introduction Our previous work1,2 showed that treatment of a bitumen froth (a bitumen emulsion containing ∼60 wt % bitumen, ∼30 wt % water, and ∼10 wt % solids) with an aliphatic solvent at a solvent-to-bitumen (S/B) dilution ratio (determined by weight) that is higher than a critical value promotes efficient separation of water and solids from the solvent-diluted bitumen oil phase. The aliphatic solvent precipitates a portion of the asphaltenes from the oil phase and results in the formation of water-solids-asphaltenes aggregates that are much larger than the original emulsified water droplets and dispersed solids. Settling of the aggregates proceeds in zone mode whereby various distinct zones, along with respective interfaces, develop during settling: an upper supernatant containing
