Hassan Hamza

Stability and settling characteristics of solvent-diluted bitumen emulsions☆

When bitumen emulsions are diluted with aliphatic solvents at solvent-to-bitumen ratios above a certain value, water droplets, solids, and precipitated asphaltenes tend to form clusters that are much larger than the individual components. This work demonstrates that bitumen emulsions diluted with aliphatic solvent exhibit settling behavior distinctly different from that of bitumen emulsions diluted with aromatic solvent. The aliphatic system exhibits a zone settling mode with sharp interfaces. A characteristic interface appears as a discontinuity between the clean oil phase and the hindered settling zone. Laboratory techniques have been developed for measuring settling rates by tracking the interface positions with time. As an example, an experimentally observed settling curve was modeled by solving the conservation law hyperbolic equations.

DESTABILIZATION OF WATER IN BITUMEN EMULSION BY WASHING WITH WATER

ABSTRACT In order to get more information about the mechanism of stabilization of water-in-diluted-bitumen emulsion, bitumen diluted with toluene (10%, 25%, and 50% in volume) was “washed” using different amounts of water (0.20% in volume). The washing water was emulsified and then separated by high-speed ultra-centrifugation. The supernatant was then used to create a second w/o emulsion with the addition of new water. Stability of the new emulsion was measured in terms of the water separation rate under a low centrifugal force It has been found that a very stable w/o emulsion was obtained in original diluted bitumen. However, after the diluted bitumen was pre-washed with a few per cent of water, the second emulsion became unstable. This indicates a significant effect of pre-washing with water on emulsion stability, possibly through the removal of emulsion stabilizing agents. Based on analytical results such as surface tension, and FTIR spectra, it appears that a small fraction of bitumen, mostly polar co...

Determination of specific heats of coal powders by differential scanning calorimetry

Abstract Specific heats ( C p ) of bituminous and subbituminous coals were investigated in the temperature range 300–360K by differential scanning calorimetry (DSC). To establish the validity of the procedure, specific heats of glass beads and graphites in powdered and bulk form were determined. Good agreement was obtained with the values for the specific heats of glass and graphites in the literature, and it was established that the specific heats were not dependent on the degree of diminution of these materials. Specific heats of coal samples were found to depend upon mesh size, temperature, rank, moisture content and whether the coal powder was wet- or dry-screened. However, there were only minor differences in C p between bituminous and subbituminous coals.

Selective Solvent Deasphalting for Heavy Oil Emulsion Treatment

Solvents are often used to treat heavy oil emulsions such as bitumen froth produced in the recovery of bitumen from oil sands. It has been found that the aromaticity of the solvent and the solvent-to-bitumen dilution ratio (S/B, by wt) have profound effects on the stability of water-in-bitumen emulsions. An aliphatic solvent at a certain S/B not only partially precipitates asphaltenes from the solvent-diluted bitumen solution, but also, at the same time, promotes aggregation of the emulsified water droplets (WD), dispersed solids (DS), and precipitated asphaltenes (PA). The WD/DS/PA aggregates exhibit zone settling in solvent-diluted bitumen, and various distinct zones and corresponding interfaces develop during settling. Typically, the top zone is a clean oil phase containing less than 0.1 wt% water– plus–solids, the middle is an emulsion zone containing the WD/DS/PA aggregates, and the bottom is a compaction zone of the settled WD/DS/PA aggregates. The position of the sharp interface that develops between the oil phase and the emulsion zone can be tracked by visual observation with the help of proper illumination. An in-line transflectance probe coupled with a spectrophotometer via a fiber-optic cable is also developed for monitoring the settling of the WD/DS/PA aggregates. The settling rate depends on many factors and conditions including solvent type, S/B, temperature, and mixing conditions. Treatment of bitumen emulsions with aliphatic solvents not only produces clean bitumen but also leads to significant reductions in asphaltene content, coking propensity, and the concentrations of metals, sulfur, and nitrogen. The viscosity of the bitumen is also reduced, which, in turn, significantly reduces the amount of light diluent that must be blended with the bitumen in order to meet the pipelining specification for viscosity. Therefore, proper selection of solvent, S/B, and other process conditions make it possible to produce bitumen products to satisfy a variety of specifications. The term heavy oils usually refers to crudes with API gravity of less than 20◦. Heavy oils with API gravity less than 10◦ are also called extra heavy oils

Study on the Mechanism of Foaming from Bitumen Froth Treatment Tailings

In the processing of Alberta oil sands, stable foams sometimes form during recovery of solvent from bitumen froth treatment tailings. This may interrupt the normal operation of the solvent recovery unit. A laboratory study was conducted to identify the cause of foam formation. Foaming behavior was observed using a glass column in which light hydrocarbon vapor was bubbled into model clay suspensions as well as samples of the actual tailings. Experimental results indicate that the stable foams occur due to presence of fine solids contaminated by bitumen fractions and are not caused by the surfactants present in the tailings water.