Browsing by Author "Daly, James G."

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    Bubble Size and Gas-Liquid Interfacial Area Measurements Using Molten Paraffin Waxes in Bubble Columns
    (American Institute of Chemical Engineers, 1987) Bukur, Dragomir B.; Patel, Snehal A.; Daly, James G.; Raphael, Matheo L.
    Experiments were conducted in 0.05 m ID and 0.23 m ID by 3 m tall bubble columns with different types of molten waxes as the liquid medium and nitrogen as the gas, under processing conditions typical or Fischer-Tropsch synthesis over iron catalysts (i.e. gas velocities up to 0.15 m s, and temperatures between 200 and 270/sup 0/C) to estimate gas liquid interfacial area from measured values of average gas hold-up and Sauter mean bubble diameter. The gas hold-up was estimated from visual observations of the expanded and static liquid heights, and the Sauter was estimated from bubble size measurements obtained by photography and dynamic gas disengagement. The paraffin wax (FT-300) used in the authors' studies is non-coalescing and has a tendency to foam. The amount of foam is greater for runs conducted in the order of increasing gas velocities, than in runs with decreasing velocities. Thus, two values of hold-up are possible and the start-up procedure determines which one will be attained. At higher gas velocities (> 0.05 m/s) the foam disappears and a transition to the slug flow, churn-turbulent regime takes place. Reactor waxes are coalescing in nature and do not produce foam. Despite similar hold-ups for the different waxes at higher gas velocities, the Sauters are significantly different and this is reflected in the specific gas-liquid interfacial areas, with larger values obtained with the paraffin wax compared to values with reactor waxes.
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    Hydrodynamics of Fischer-Tropsch Synthesis in Slurry Bubble Column Reactors
    (1987) Bukur, Dragomir B.; Daly, James G.; Patel, Snehal A.; Raphael, Matheo L.; Tatterson, Garry B.
    An improved photographic technique was employed to obtain pictures, for bubble size analysis, in experiments conducted in the Unit AMk2G (511 cm ID, 305 cm tall glass column)] During these experiments measurements of the average gas hold-up were made at 200 and 265oc using FTk300 paraffin wax as the liquid medium and nitrogen as the gas. Additional experiments were performed adding oxygenates, stearyl alcohol and stearic acid, (5 - 10 % by weight) to the wax at a temperature of 265°C. The addition of oxygenates did not have a significant effect on the average gas hold'up.