Behavior of tar sand bitumen with paraffinic solvents and its application to separations for athabasca tar sands

Abstract

A study was made of the dissolution of tar sand bitumen using low‐molecular‐weight paraffinic solvents at essentially ambient temperatures. The experimental data were obtained using the spinning disc technique, liquid‐fluidized beds, and direct particle‐size analysis of the insolubles. The results are consistent with a mechanism where the paraffins leach the soluble oil from the bitumen and leave behind a porous network of insoluble asphaltenes. This phenomenon of oil diffusing through an asphaltene layer was modeled using Fick's law for unsteady‐state diffusion. An understanding of the mechanism of bitumen extraction with paraffins and also the effect of fluid mechanics in the tar sand system have been applied to obtain a novel separation of deasphalted oil and asphaltenes from Athabasca tar sands. This new separation technique has the potential of simplifying downstream processing for the bitumen and also of avoiding environmental problems associated with the present tar sand extraction technology.

Critical review of mutual diffusion coefficient measurements for liquid solvent + bitumen/heavy oil mixtures

“…The resolution limitation can influence both the Spinning disk [1] Extremely short run time Uncertain analysis procedure, Unclear measurement of leached-out bitumen, concentration independent, ambient conditions Modified transpiration [3] Short run time, clear and robust analysis procedure, applicable to extremely high bitumen concentrations Concentration independent, ambient conditions, time lag error Taylor dispersion [5] Short run time, clear and robust analysis procedure, elevated desired temperature conditions, not influenced by volume change upon mixing Concentration independent, unexplained double-maximum behaviour of dispersion peaks Nuclear magnetic resonance [6][7][8][9][10] Accurate average concentration measurement Long run time, dependence on another technique like X-ray to measure penetration depth, concentration independent, uncertain analysis procedure, ambient conditions Laser transmission imaging [11] Concentration dependent, the whole composition range Imprecise use of Beer-Lambert's law, need to use smoothed composition profiles, uncertain analysis procedure, influenced by volume change upon mixing, long run time, ambient conditions X-ray transmission imaging [7,9,12,14] Concentration dependent Imprecise use of Beer-Lambert's law, need to use smoothed composition profiles, unreliable analysis procedure, not the whole composition range, influenced by volume change upon mixing, long run time, ambient conditions X-ray transmission imaging [13,14] Concentration dependent Imprecise use of Beer-Lambert's law, need to use smoothed composition profiles, difficult and unreliable analysis procedure, not the whole composition range, influenced by volume change upon mixing, long run time, ambient conditions X-ray transmission imaging [14] Likely reliable analysis procedure, concentration dependent Imprecise use of Beer-Lambert's law, need to use smoothed composition profiles, not the whole composition range, influenced by volume change upon mixing, long run time, ambient conditions Visible light transmission imaging [15] Simple apparatus, visible light, extremely short run time, concentration dependent Imprecise use of Beer-Lambert's law, uncertain analysis procedure, influenced by volume change upon mixing, not the whole composition range, ambient conditions concentration profile shape and its values. The resolution limitation can influence both the Spinning disk [1] Extremely short run time Uncertain analysis procedure, Unclear measurement of leached-out bitumen, concentration independent, ambient conditions Modified transpiration [3] Short run time, clear and robust analysis procedure, applicable to extremely high bitumen concentrations Concentration independent, ambient conditions, time l...…”

“…More accurately, at later diffusion times where density gradients are low, Equation (14) can be safely employed, provided that the gradients are experimentally detectable outside the error of measurement. 15 3.90-60 $0-80% by volume solvent [14] N-decane Athabasca bitumen 298.15 0.0650 Solute finite dilution [1] Iso-hexane bitumen: m ¼ 56.5 Pa s @ 298.15 K 296.15 AE 1.5 0.701 Solvent finite dilution [3] bitumen: m ¼ 56. The slopes and intercept approach for the analysis of concentration profiles appears to be more reliable than the Boltzmann-Matano approach.…”

“…where C s,n is the concentration of the volatile solvent in nitrogen gas, Q is the volumetric flow rate of nitrogen gas at [1] Modified transpiration [3,4] Taylor dispersion [5] Nuclear magnetic resonance [6][7][8][9][10] …”

“…Since the seminal work of Funk, [1] studies of mutual diffusion in solvent þ bitumen/heavy oil systems fall into two general categories: gas and liquid solvents; the latter is the subject of this review. In particular, the diffusive mass transfer process in solvent þ bitumen/heavy oil mixtures has been investigated thoroughly in both modelling and experimental scopes.…”

Partitioning of Bitumen-Solvent Systems Into Multiple Liquid Phases

“…Some of the early works in the area of solvent use for bitumen recovery have been in the area of supercritical extraction using light hydrocarbons (2) . Funk (3) experimentally studied the dissolution of bitumen using excess amount of lowmolecular-weight paraffinic solvent at ambient temperatures. The paraffinic solvents separate the bitumen into de-asphalted oil and an asphaltene fraction.…”