Search

The present study is the first part of research into modeling flocculation processes in a tubular reactor with different width baffles. Computational fluid dynamics numerical simulation methods were used to identify intensive mixing zones and turbulent flow zones. The influence of geometry and baffle width on velocity components of the liquid flow and turbulence parameters was analyzed. The obtained results were represented as vector and contour distribution maps of the determined quantities. Flow visualization was performed to illustrate the structure and size of vortices formed behind baffles. The correctness of the numerical model was experimentally validated based on anemometric measurements using laser Doppler anemometry (LDA) method. [ABSTRACT FROM PUBLISHER]

Froth flotation is one of the most frequently used processes for separation of valuable from gangue minerals. Modeling and simulation of the flotation process is a difficult task because of nonlinear and dynamic nature of the process. In this contribution, the relationship between the process variables (i.e., gas flow rate, slurry solids%, frother/collector dosages, and pH) and the metallurgical parameters (i.e., copper/mass/water recoveries and concentrate grade) in the batch flotation of a copper sulfide ore is discussed and modeled. Statistical (i.e., nonlinear regression) and intelligent (i.e., neural network and adaptive neuro-fuzzy) techniques are applied to model the process behavior at different conditions. The results indicate that intelligent approaches are more efficient tools for modeling of the complicated process like flotation, which are of central importance for development of the model-based control systems. [ABSTRACT FROM PUBLISHER]

This paper deals with an analytical method to assess the maximum temperature value along a tubular chemical reactor at steady state. This reactor is provided with a jacket in which a counter current cooling liquid flows. The thermal behavior of the chemical reactor is calculated with the McCormack numerical method. Comparison of the exothermic reaction generated flux with the removed flux from the separating wall leads to a two-part reactor subdivision. In the first part, the reactor behaves as an adiabatic reactor followed by a zone in which the flux removed from the wall is not negligible and remains constant. In the second part, the reactor behaves like a simple heat exchanger without internal energy source. Analytical integration of mass and energy balance equations in each subsystem was used to determine the analytical expression of maximum temperature. [ABSTRACT FROM PUBLISHER]

Abstract: The knowledge of thermal properties of technical components or internals in chemical reactors is often a key characteristic for planning and designing chemical engineering processes. As an alternative to packed beds or packings, sponges turned out to be used in new application fields in chemical and process engineering. Therefore an experimental study was performed to investigate the two-phase thermal conductivity of solid ceramic sponges made of alumina, mullite and oxidic-bonded silicon carbide (OBSiC) at moderate temperatures. A two-dimensional model is used for analysing the measured temperature profiles and for calculating the thermal conductivity. It can be observed, that the thermal conductivity increases with decreasing porosity and is nearly constant when the pore size (ppi number) is varied. The thermal conductivity data are modelled by an approach similar to the well known Krischer model. Compared to a packed bed of spherical particles, the values of the thermal conductivity of sponges turn out to be about five times higher. [Copyright &y& Elsevier]