Dewatering of Poor-Quality Bitumen Froth: Induction Time and Mixing Effects

Abstract

The impact of mixing conditions on the removal of water and solids from high-water, poor-quality bitumen froth was explored. Naphtha diluent and a demulsifier were added to improve removal of water and solids from bitumen froth. The mixing and subsequent settling of this system were carried out in the confined-impeller stirred tank, a lab-scale mixing test vessel with well-characterized, relatively uniform mixing conditions. A protocol for finding the proper demulsifier dosage at which to study mixing effects was applied successfully. High mixing energy J and the predilution of demulsifier (characterized by its injection concentration IC) improved dewatering and solids removal performance, agreeing with earlier studies in diluted bitumen and bitumen froth of higher quality (Laplante et al. Fuel Process. Technol. 2015, 138, 361–367; Arora, N. Mechanisms of Aggregation and Separation of Water and Solids from Bitumen Froth Using Cluster Size Distribution, 2016). An unexpected finding was that dewatering was significantly delayed in poor-quality froth: it was not detectable until up to 45 min in some cases. This induction time was replicated and was clearly impacted by changes in the mixing conditions.

Effective sapphire repellency treatment to reduce fouling of a focused beam reflectance measurement (FBRM) probe in bituminous systems

“…This is a lab‐scale mixing test vessel, designed to provide well‐characterized and relatively uniform turbulent mixing conditions at bench scale as reported by Komrakova et al The CIST has a volume of ∼1 L, a diameter (T) of 76 mm, and a liquid height (H) of 228 mm . The experimental setup and procedure are described by Saraka . Five Rushton (D = T/2) or six Intermig (D = 2T/3) impellers were used in the experiments.…”

“…The fluid was a mixture of naphtha and bitumen froth, an intermediate product in the oil sands extraction process which comprises oil, water, and solids. In the data discussed in this work, the bitumen froth was ∼50 % bitumen, 37 % water, and 13 % solids . After mixing with naphtha, the diluted froth was maintained at 80 °C throughout the experiment.…”

“…Focused beam reflectance measurement (FBRM) is a measurement technique that allows for in‐situ dynamic measurements of particle or drop sizes in a process. The FBRM probe is used extensively in crystallization processes and a number of processes with a solid dispersed phase, as well as in the study of liquid/liquid dispersions and more recently it has been applied to crude oil systems . The FBRM probe directs a laser beam through a sapphire window into the fluid and collects backscattered light.…”

“…The performance of chemical demulsifiers in water removal from bitumen froth systems has been extensively studied by our research group for several years. Recent publications have shown that mixing variables may be as important as the bulk demulsifier concentration for effective dewatering of both bitumen froth and diluted bitumen . In fact, if the mixing conditions are adjusted by increasing the mixing energy and decreasing the demulsifier injection concentration, the amount of demulsifier needed to achieve dewatering may be reduced by 50 % …”

“…We have recently started using a Mettler Toledo G400 FBRM 19 mm probe . The probe has been used to track changes in the chord length distribution during demulsifier dispersion and water settling . The FBRM probe presents some challenges when used in bituminous systems.…”