Chemical Engineering & Technology

Pulsation of fluids within channels equipped with obstacles allows for intensifying of transverse transport and of heat and mass transfer, independent on the residence time. Special arrangements are even able to induce directional flow despite of harmonic flow drive. It can be assumed that pulsating of fluids opens new fields of still only partly examined effects.

A wide number of correlations exist for effective diffusivity in the modeling of packed-bed reactors in a one-dimensional pseudo-homogeneous manner. These correlations are described in detail and a model is defined that should be used prior to experimentation in order to ensure chemical kinetic results are not significantly influenced by diffusion phenomena.

Micronized genipin with a mean particle size of 1.8 μm was prepared by the antisolvent precipitation process. The chemical structure of micronized genipin remained unchanged, but the crystallinity was reduced. The dissolution rate and solubility of the micronized genipin were 2.08 and 1.64 times that of the raw drug, and the amounts of residual n-hexane and ethanol were lower than the International Conference on Harmonization limit for solvents.

Hydrodynamics of a gas-liquid flow through trickle beds and the influence of tortuosity and fluid volume fractions on trickle-flow bed performance were investigated experimentally and numerically. The effects of catalyst loading methods, liquid and gas flow rates on pressure drop and liquid holdup through a trickle-bed reactor with sharp corners are discussed.

A method for pilot-scale production of carbon molecular sieve hollow fiber membranes is presented which was proved to reproducibly generate high product yields. These materials have been receiving significant attention as robust alternatives to traditional polymeric membrane materials and as a cost-effective surrogate for inorganic sieving membranes.

Performance of various non-uniform catalysts are investigated with the aim of maximizing the C₅⁺ yield of the Fischer-Tropsch process. The effects of the active com-ponent distribution along the bed as well as the feed and cooling temperature are studied.

In gas-phase hydrogenolysis of glycerol, Cu/Al₂O₃ catalysts with high acid strength of weak and strong acid sites and small-sized metallic copper favored the formation of propanediols, ethylene glycol and monohydric alcohols. Cu/TiO₂ and Cu/ZnO catalysts with low acid strength of weak acid sites and large-sized metallic copper favored the rapid dehydration of glycerol to hydroxyacetone.

The traditional C3 chain is profoundly changed by diverse factors like the increasing on-purpose propylene production technologies and biotechnological processes. Alternative processes for the production of propylene and its derivatives have been aggressively pursued. The status of the game-changing technologies related to the C3 value chain and the relevant factors and implications are discussed.

The conversion of carbon dioxide to microalgal biomass was investigated as a feasible option for carbon capture and storage. The new approach consists in the application of an air-lift reactor to flue gas treatment using a Spirulina platensis culture for the absorption of carbon dioxide, with the simultaneous abatement of nitrogen oxides.

The performance of a new class of liquid-liquid hydrocyclones designed for the separation of dilute aqueous emulsions of oil is presented. The influence of different parameters was studied experimentally and numeri-cal simulations were carried out by CFD techniques. The improvement of this separation technology can contribute to the reduction of environmental impact in the discharge of the produced water.

A simple correlation is developed to estimate the mixing ratio for saturated air over water as a function of pressure and temperature using an Arrhenius-type asymptotic exponential function. To show the simplicity of the model and the usefulness of the novel predictive tool, the formulation is discussed in a systematic manner.

An ellipse gate impeller was designed for fermentation processes with varying fluid viscosities in order to cover turbulent to transient or even laminar flow regimes in a reactor. Hydrodynamics characteristics were investigated by experimental and numerical methods, indicating excellent mixing properties of this impeller in a wide range of Reynolds numbers.

Degradation of toxic dyes in colored wastewaters poses a major problem in the textile industry. In this study electrochemical incineration of such dyes is investigated, using Pt electrodes coated with a mixed metal oxide film of IrO₂-SnO₂-Sb₂O₅. The films were prepared using the Pechini method and used in an electrochemical flow cell reactor to oxidize organic material under different conditions in order to evaluate their application.

An innovative catalytic method for the synthesis of a water-soluble poly(3,4-ethylenedioxithio-phene) in the presence of poly(styrene sulfonate) with Fe^IIITSPP, Co^IIITSPP, Mn^IIITSPP, and Cu^IITSPP as effective catalysts is described. This one-step approach is particularly attractive in that it is simple and requires minimal separation and purification.

Ozonation bubbly flow was investigated through volume-of-fluid (VOF) simulations and electrical capacitance tomography (ECT) data. The VOF framework accurately predicted the effect of several physicochemical variables. Gas-liquid velocity distribu-tions were positively correlated with pollutant removal efficiencies. The interstitial flow maps identified by ECT and computed by the VOF model gave rise to unsteady flow patterns.

The feasibility of hexavalent chromium elimination from synthetic effluents using red onion skin as adsorbent via a combined synergistic electrocoagulation sorption process is examined. The effects of the operating conditions to perform the adsorption process, the electrocoagulation process, and finally the hybrid process were evaluated and compared.

A simplified computational model is presented for the semi-dry desulfurization process based on the Euler-Lagrange particle tracking method. The model simulates spraying of the lime slurry into the absorber with a twin-fluid nozzle and solves for the heat and mass transfer between the flue gases and the slurry droplets and a basic chemical reaction. The resulting desulfurization efficiency is compared with data from the literature.

Accident contributors in the chemical process industry were studied based on the Failure Knowledge Database. The accident contributors were ranked in accordance with their frequency and importance in accident prevention. An interconnection matrix to study the relationships between the contributors revealed three functional groups of accident contributors.

A 3D computational fluid dynamics simulation is carried out to predict the dehydration of aqueous solutions by means of a membrane evaporation process. A combined finite element and UFPACK method is applied for simulations. The results indicate good agreement between experimental and simulation results. The proposed model proved to be suitable for predicting the performance of a membrane evaporator.

Using the results from the nonlinear analysis of pinch maps and the feed angle method as an efficient shortcut approach, a systematic procedure is proposed for the concep-tual design of double-feed reactive distillation columns. The feasibility and the practicable range of operating parameters are assessed and discussed. The method is automated and computa-tionally efficient.