(140a) Resolving Sampling Inaccuracies Through Numerical Study of Liquid-Liquid Vertical Dispersed Flows

In the post-production, downstream processing of heavy oil and bitumen, surface treating facilities often involve vertical flows of mixtures containing droplets of oil, fine solid particles and water. In some cases, ISOLOK^TM (piston) samplers are used to withdraw samples from the main flow for composition analysis (i.e. per cent of oil, water and solids in the mixture). The results are used for mass balancing and for process trouble-shooting. Plant operators, on numerous occasions, found that other measurements indicated that the oil composition in these samples was lower than expected, but there was no way to verify this with field measurements. As a result, numerical simulations of liquid-liquid dispersed flow in a vertical pipe were carried out using the two-fluid approach implemented in ANSYS CFX. A dispersion of oil in water (where water is the continuous phase) was studied.  A comparison of the present numerical results with previous experimental results showed that, depending on the droplet size and droplet size distribution, the volume concentration of oil at the pipe radius where the ISOLOK^TM sample is collected could be 50% lower than the bulk (average) concentration. The results of this study have the industry looking for improved method of sample collection as well as on-line, real-time composition measurement techniques.