Modellierung und Simulation von Strömungen und biologischen Reaktionen innerhalb eines Belebtschlammbeckens

With the aim to increase the efficiency of the aeration tanks of municipal wastewater treatment plants, the implementation of a biological model system (ASM1) into the CFD code ANSYS CFX® is presented for modeling a full‐scale aeration tank and verified with experimental data. Taking into account the biological processes, hydrodynamics and gas‐liquid mass transfer, simulations were performed and compared to experimental concentration profiles for ammonium and nitrate. The assumptions made are explained in detail. While the simulated ammonium concentration profile is in good agreement with the measured values, deviations occur for the nitrate profile. However, the CFD simulations exceed the prediction accuracy of conventional 0D simulation software.     

Eindimensionale Modellierung und Simulation von Blasensäulenreaktoren

Reactor models that feature a practical way to design bubble columns on the (semi‐)industrial scale have been published only rarely in the scientific literature. Creating a one‐dimensional model in the equation‐oriented simulation software ASPEN Custom Modeler^TM, a compromise between model precision and modeling can be reached. The model quantitatively describes the processes in a bubble column reactor with sufficient accuracy.     

Die Modellierung von Stofftransportprozessen in Mehrphasenströmungen – am Beispiel des Strahlzonen‐Schlaufenreaktors

The efficiency and selectivity of chemical reactions are influenced by the mixing characteristics of the reactor. Existing models often assume homogeneous mixing on micro scale to calculate the reaction yield. However, neglecting the local hydrodynamic phenomena causes a discrepancy between model calculation and experimental data especially considering mass transfer limited reactions. In two‐phase flows different mass transfer phenomena have to be considered: the diffusion in the gas‐liquid boundary layer and diffusion in the Batchelor layer. The aim of the paper is to describe the mass transfer affecting mechanisms in multi‐phase flows and to discuss the first results of the investigation of local mass transfer phenomena in a two phase flow driven jet‐zone loop reactor.     

Gasphasensynthese von Kern/Mantel‐Partikeln am Beispiel von TiO2‐Nanopartikeln mit elektrisch leitendem Mantel

An advanced process enables synthesis and coating of individual TiO₂‐core particles with a shell of transparent conducting oxide (TCO) from the gas phase in one reactor. TiO₂ particles were coated with fluorine‐doped tin oxide (SnO₂:F) or antimony‐doped tin oxide (SnO₂:Sb). Specific electrical conductivity of the core/shell particles was up to 8 · 10^–3 S cm^–1. Variation of process parameters allows modifying dopant level and conductivity in an easy way.     

Scale‐up und detaillierte Prozessanalyse eines Membranreaktors am Beispiel einer heterogen katalysierten Veresterung

The combination between reaction and pervaporation has been investigated using the example of a heterogeneous catalysed esterification reaction. The process model parameters have been determined based on experimental investigations and a scale‐up has been performed to the pilot scale. A detailed process analysis leads to optimal operating as well as structural variables and two separation sequences have been suggested.