Showing papers by "Jyeshtharaj B. Joshi published in 1981"

Invited review hydrodynamic and mixing models for bubble column reactors

Abstract: The knowledge of the flow patterns of each phase of bubble column reactors is of considerable importance for the rational design and scale-up The hydrodynamic models for the liquid phase have been reviewed The models have been based on some form of pressure balance or energy balance These two approaches have been compared and recommendations have been made regarding the range of applicability of the individual models A comparison between the predicted and the experimental liquid velocities has been presented whenever possible The range of variables has been pointed out for which further investigations are needed The empirical and theoretical models for the mixing behavior of the different phases of bubble column reactors have also been reviewed

Modeling of three phase reactors: A case of oxydesulfurization of coal

Abstract: Mathematical models have been developed for the design of bubble column slurry reactors, wherein the solids take part in the reaction and follow the shrinking core model. The cases of liquid film control, ash diffusion control, and chemical reaction control have been analyzed. Experiments were performed in a 22.2 mm i.d. continuous cocurrent bubble column slurry reactor for the removal of pyritic sulfur by oxidation from aqueous slurries of Upper Freeport, Lower Freeport, Kentucky No. 9, and Pittsburgh seam coals, in the temperature range of 430-480°K at 6.8 MPa total pressure. The theoretical predictions are found to be in good agreement with experimental results.

Kinetics of oxydesulfurization of minshall, indiana coal

Abstract: The kinetics of the oxidation of pyritic sulfur, organic sulfur and carbon for the Minshall, Indiana coal was investigated. Experiments were conducted in a semi-batch manner. The experimental data were taken in the temperature range of 19O–23O°C, oxygen partial pressure range of 0.86-3.44 MPa and for the batch times up to 3600 s. The rate of organic sulfur removal was observed to be second order with respect to sulfur and first order with respect to the partial pressure of oxygen, and this reaction was found to have an activation energy of 75,000 kJ/kg-mole. The pyritic sulfur removal was observed to be much more rapid, and the experimental data fitted the continuous reaction model with second order dependence on pyritic sulfur. However, the coal combustion loss in the case of this coal was relatively high, probably because of the presence of larger amounts of oxygen containing compounds, and this coal did not meet the EPA standards for the heating value losses.