OBSERVATION OF HEAVY OIL VAPORIZATION UNDER RAPID HEATING

The pyrolysis and coking of samples of Athabasca bitumen and its penta ne-insoluble fraction were observed under rapid heating conditions. Sa mples were suspended on a thin rod and heated with radiant heaters und er vacuum. Images were recorded using a CCD camera system. Samples wer e heated for 2 s to give inside temperatures as high as 673 K in a 1 m m droplet. The heating rates at the exterior surface of the samples ex ceeded 680 K/s. Important variables included the composition, shape, a nd size of the sample. Temperature measurements depended on the locati on of the thermocouple in the sample and the size of the thermocouple. The observations showed that the Liquid phase rapidly evolved a cloud of vapor, which was bright and luminous under the radiant heaters. Th e rate of formation and expansion of the cloud depended on the volatil e content of the sample. The samples were liquid under the observation conditions, but even under vacuum, the liquid did not foam or froth s ignificantly once vapor evolution had begun. These observations sugges t that pyrolysis and coking of liquid droplets and films can be modele d using the simple geometry of the liquid phase, rather than expanded vapor-liquid foams.