John A. Ruether

Dispersed solid dynamics in a slurry bubble column

Abstract New data and theory are presented for describing dispersed solids in slurry bubble columns. Axial solids concentration distributions were measured in a 0.108 m.i.d. slurry bubble column apparatus operated at steady-state conditions. Slurry and gas superficial velocities ranged from 0.0 to 0.02 m/s and 0.03 to 0.20 m/s, respectively. The liquid-phase was either water or ethanol, and the solid-phase consisted of narrow-sized fractions of glass spheres. With a one-dimensional sedimentation-dispersion model, the data have been used to develop a method for predicting average solids loading and axial distribution of solids in a bubble column. Correlations are given for the hindred settling velocity, the solids dispersion coefficient, and the solids concentration at the top and bottom of the column. A solids distribution function is derived using one parameter that contains the hindred settling velocity and the solids dispersion coefficient. The new method is applied to data from the literature for three slurry bubble columns with diameters in the range of 0.066–0.286 m. The new method predicts axial distribution of solids with improved accuracy over existing methods, especially for non-aqueous systems and for those with low slurry feed concentration or high settling velocity.

Coal liquefaction using ore catalysts

Abstract Ores and ore concentrates containing minerals of Co, Mo, Ni, Fe, and other potentially active metals have been investigated as slurry catalysts for liquefaction of Blacksville mine, Pittsburgh seam, bituminous coal. The tests were conducted batchwise in a stirred autoclave for 30 min at 425°C and 13.79 MPa (2000 psig) hydrogen pressure according to a two-cycle scheme. In the first cycle, the reaction charge consisted of ground coal, catalyst, hydrogen, and SRC-II heavy distillate. The product of the first cycle was hot-filtered, and the liquid product served as a vehicle for the second cycle, which was otherwise run identically to the first. Reaction products from each cycle were analysed to determine conversion of coal, yield of liquids, liquid product viscosity, and group type (preasphaltene, asphaltene, and oil). Mixtures of ores containing iron pyrites and minerals containing other catalytically active transition metals were compared to pyrites alone and to a pulverized supported Co-Mo-alumina catalyst. An ore catalyst containing both Fe and Ni was superior to another that contained an equivalent mass of iron alone. The best ore catalysts tested, in terms of high liquid yields and low product viscosities, were mixtures of pyrites and molybdenum- and cobalt-containing ores. The latter yielded results that approached those obtained with an equivalent mass of cobalt and molybdenum on an alumina support.

Fractional destraction of coal-derived materials

Abstract The use of supercritical fluids to fractionate coal-derived distillate and residuum in a manner analogous to conventional fractional distillation is reported. Fractionation based upon volatility is observed when a fluid density gradient is established in the unit to promote reflux.

Temperature dependence of liquid density: the choice of a reference state

Abstract Some reduced equations of state where the scaling parameters are different from the parameters for the liquid-vapor critical point were studied. The problem is pertinent for many compounds for which the critical point cannot be reached. First, calculations were made for the equation of Shelomentsev and Bolotin, both in its original form and in our modification where the scaling parameters pertain to both the normal melting point and the normal boiling point. Good results were obtained for saturated liquid densities of normal paraffins, but the inconvenience of dealing at the same time with two physical reference states remains. Second, a modified Guggenheim density equation was used, but with the parameters at the normal boiling point instead of at the critical point. Again for n-paraffins, good results were obtained both for density and for isobaric expansivity. Two characteristic parameters for each material are needed. Two ‘universal’ parameters, the same for all paraffins, can be used also, but the predictive accuracy is somewhat lower.

Explosive comminution of bituminous coal using steam

Etude parametrique de la comminution du charbon par explosion dans de la vapeur. Influence de la temperature (347-506 o ), pression (2400-5000 psig), concentration de la suspension de charbon, et vitesse de chauffe sur la communication et la desulfuration. Les donnees sur la taille des particules et les micrographies SEM demontrent le role des proprietes thermoplastiques dans le processus