Swati Mohanty

MODELING OF LIQUID-LIQUID EXTRACTION COLUMN: A REVIEW

Mathematical models are reviewed for different types of commonly used extraction columns, viz. pulsed sieve plate column, rotating disc contactor, Kuhni column, spray column, Scheibel extractor, packed column, Oldshue-Rushton contactor and reciprocating plate column. In addition, numerical techniques, process simulators and some estimation methods for model parameters have also been included. The review cites over 120 references.

Hydrocracking: a review

Abstract In this article the technology, kinetics, chemistry and reactor modelling of hydrocracking have been reviewed. While it is intended to provide a general overview of the recent advances in this process, greater emphasis has been given to technology and reactor modelling because of their industrial importance. Over ninety references have been cited.

Modeling of a hydrocracking reactor

Abstract A three parameter model has been developed for a two-stage vacuum gas oil hydrocracker unit. The feed and the products were lumped into 23 pseudocomponents, each characterized by its boiling range and specific gravity. The model assumes that each pseudocomponent can only form lighter products by a pseudohomogeneous first order reaction. The model parameters were determined using information from literature and plant data. Given the feed characterization and the inlet conditions, the concentration and temperature profiles throughout the reactors, the amount of recycle and hydrogen consumption can be calculated. The model was validated against plant data and the agreement was generally good. The effect of variation in the model parameters and operating conditions has also been discussed.

Dielectrophoretic separation of micron and submicron particles: a review.

This paper provides an overview on separation of micron and submicron sized biological (cells, yeast, virus, bacteria, etc.) and nonbiological particles (latex, polystyrene, CNTs, metals, etc.) by dielectrophoresis (DEP), which finds wide applications in the field of medical and environmental science. Mathematical models to predict the electric field, flow profile, and concentration profiles of the particles under the influence of DEP force have also been covered in this review. In addition, advancements made primarily in the last decade, in the area of electrode design (shape and arrangement), new materials for electrode (carbon, silicon, polymers), and geometry of the microdevice, for efficient DEP separation of particles have been highlighted.

Multiobjective optimization of synthesis gas production using non-dominated sorting genetic algorithm

Abstract Synthesis gas finds wide applications in various chemical industries. Various routes for manufacture of synthesis gas have been reported such as steam reforming of methane, carbon dioxide reforming of methane, partial oxidation of methane and combination of both carbon dioxide reforming and partial oxidation of methane. However, very few studies have been reported on optimization of process parameters for synthesis gas production. These processes have multiple objective functions that are conflicting in nature and hence use of single objective optimization technique is not suitable. In this study therefore real parameter non-dominated sorting genetic algorithm has been used to obtain a Pareto optimal set of process parameters for production of synthesis gas from combined carbon dioxide reforming and partial oxidation of natural gas over a Pt/γ-Al2O3 catalyst. The objectives are to maximize the conversion of methane, maximize the selectivity of carbon monoxide and maintain the hydrogen to carbon monoxide mole ratio at approximately 1. The variables that have been taken are temperature, gas hourly space velocity and the oxygen to methane mole ratio. The results have been compared with that reported by other authors.

Drag correlation for dilute and moderately dense fluid-particle systems using the lattice Boltzmann method

Abstract This paper presents a numerical study of flow through static random assemblies of monodisperse, spherical particles. A lattice Boltzmann approach based on a two relaxation time collision operator is used to obtain reliable predictions of the particle drag by direct numerical simulation. From these predictions a closure law F ( Re p , φ ) of the drag force relationship to the bed density φ and the particle Reynolds number Re p is derived. The present study includes densities φ ranging from 0.01 to 0.35 with Re p ranging up to 300, that is compiled into a single drag correlation valid for the whole range. The correlation has a more compact expression compared to others previously reported in literature. At low particle densities, the new correlation is close to the widely-used Wen & Yu – correlation. Recently, there has been reported a discrepancy between results obtained using different numerical methods, namely the comprehensive lattice Boltzmann study of Beetstra et al. (2007) and the predictions based on an immersed boundary – pseudo-spectral Navier–Stokes approach (Tenneti et al., 2011). The present study excludes significant finite resolution effects, which have been suspected to cause the reported deviations, but does not coincide exactly with either of the previous studies. This indicates the need for yet more accurate simulation methods in the future.

Polymers from renewable resources. Part 3. Thermal analysis of the interpenetrating polymer networks derived from castor oil, polyurethane—polyacrylates

Abstract A number of polyurethanes (PU) were synthesized by reacting castor oil with hexamethylene di-isocyanate and varying the NCO/OH ratio. All polyurethanes were reacted with acrylamide using EGDM cross-linker and benzoyl peroxide initiator. Thermogravimetric analyses of the polymers were followed, using a computer analysis method, the LOTUS package, for assigning the kinetic mechanism. Various kinetic equations have been used to evaluate the kinetic parameters. The suggested mechanism of degradation of the interpenetrating polymer networks (IPN) are based on the kinetic parameters.

A simplified hydrodynamic model for a pulsed sieve-plate extraction column

Abstract A simplified stage-wise hydrodynamic model for simulation of a pulsed sieve-plate extraction column has been presented. The model is based on a drop population balance which takes into account drop breakage and coalescence in each stage. Each stage is represented by the actual column compartment between two sieve plates. Although experimental break-up parameters have been used in the model, the coalescence coefficients have been taken as the fitting parameters and the values which gave the best fit with the experimental data have been used. The predicted values have been compared with data from two different diameter pilot plant columns and the agreement is found to be quite satisfactory for the system butylacetate-water. The model can be used for coalescence parameter estimation of different drop sizes, which will be taken up as part of the extension of the present work.

Prediction of saturated liquid volumes of organic compounds

A method based on a generalised form of the Rackett equation is proposed for predicting the volumes of organic liquids in the entire saturated liquid region. The method requires data on the normal boiling point, critical temperature and the chemical structure only as inputs. Liquid volumes predicted by the proposed method gave 1.7% average absolute deviation and a maximum absolute deviation of 8.3% from the literature values for the 144 organic liquids (836 points) tested over temperatures ranging from the freezing point to the critical point.

A new method for predicting critical volumes of organic compounds

Abstract A new method based on atomic and structural contributions is proposed for estimating the critical volumes of organic liquids. The proposed method gives more accurate values compared with the methods of Lydersen, Joback and Somayajulu, the average absolute deviations being 2.3%, 3.2%, 3.1.% and 2.7% respectively for these four methods when tested against the experimental data for 279 organic liquids. The methods of Ambrose and Fedors recommended by the API technical data book for hydrocarbons and the AIChE data prediction manual for non-hydrocarbons gave overall average deviations of the same order as those for the Lydersen et al. method. The proposed constants can also be used to calculate the volume of liquids at the normal boiling point, with accuracies better than or comparable to those of the existing methods.