Interfacial Area Distribution Research Articles

Optimization of gas–liquid reactor using computational fluid dynamics

The relationship between the geometry and the operating conditions, hydrodynamics and performance of an industrial gas–liquid stirred reactor has been studied with the help of CFD modeling and gamma ray tomography. It is seen that the interfacial area distribution is very wide. This in some areas leads to mass transfer limitations. Strategies for retrofitting the reactor were then developed (e.g. change in the operating speed, change of impeller type, change in the feed introduction, etc.) and tested by CFD for improving the reactor performance. The benefits of the implementation were in terms of the improvement in the product quality, reduction in the by-product formation, increase in the reactor throughput.

Polymer Adsorption/Retention in Porous Media: Effects of Core Wettability and Residual Oil

ABSTRACT Low polymer retention in the reservoir is essential to the success of a polymer EOR operation. It is usually estimated from laboratory core flood experiments conducted under conditions as close as possible to those prevailing in the field. This paper addresses the effects of core wettability and oil saturation on polymer adsorption/retention. Adsorption of EOR water-soluble polymers onto oil or, more generally, hydrophobic substrates was estimated from a series of core flood experiments on alkane-coated (silane-treated) substrates and compared to adsorption on the bare siliceous substrates. A significant adsorption onto hydrophobic surfaces was found, the effect being stronger for nonionic Polyacrylamide and polysaccharides (scleroglucan and xanthan) than for anionic (hydrolyzed) Polyacrylamides. In a second series of core flood experiments, Polyacrylamide adsorption/retention in cores under residual oil saturation was measured and compared to the adsorption/retention in similar oil-free, 100% brine saturated, cores. In oil-wet cores, retention decreased considerably in the presence of oil, while it increased slightly in water-wet systems. These effects may be explained in terms of water/rock and water/oil interfacial area distribution within the pore space, which is governed by wettability. In water-wet cores, droplets of residual oil offer an additional adsorbing surface to the polymer, whereas in oil-wet cores the oil wetting film offers the polymer an adsorbing surface much smaller than the (no longer accessible) rock surface.

TRANSIENT MASS AND HEAT TRANSFER FROM A CLOUD OF VAPORIZING DROPLETS OF VARIOUS SIZE DISTRIBUTIONS: A SECTIONAL APPROACH

A population of vaporizing liquid droplets of a wide range of sizes suspended in a stagnant heated atmosphere is considered. Interaction between neighboring droplets is taken into account through the ‘cooling effect’ due to latent heat absorption. To avoid the dimensionality problem associated with the discrete form of droplet population balance equations, “sectional-conservation-equations” are used. Since droplets of various sizes differ in their vaporization rates, “sectional-vaporization-coefficients” are presented. New solutions for the coupled energy and sectional size distribution equations arc presented and the transient changes in droplet size distribution are analyzed. The analysis takes into account the density of the spray, the distribution of interfacial area between the phases, rates of droplet vaporization, and the properties of the surrounding vapor-gas mixture. All the above-mentioned properties of the spray and surrounding gas are combined here to form a new nondimensional group-vaporizat...