Entwicklungsstand und Perspektiven der Modellierung von Transportvorgängen in durchströmten Festbetten

New model equations enable the consistent and accurate calculation of heat transport, mass transport and chemical reactions in packed beds with fluid flow. The main features of this approach are reviewed and summarized, and selected aspects are discussed. The modelling approach may be a good starting point for the development of, for instance, membrane reactors and separation processes such as chromatography or freeze drying for thermally sensitive products.     

Geschwindigkeitsverteilung und Gasdruckschwankungen in querdurchströmten Behältern

In the process engineering industry tanks with large volumes from 250 to 1000 m³ are often required, which are flowed through by large gas volume flows up to 150 000 m³h^–1. The flow leads to a mean flow velocity from 0.347 – 1.0 m s^–1. The inflow and outflow of the gas have to be done by one or two inlet and outlet pipes with diameter sizes of 1.20 to 2.0 m. Nevertheless, with respect to the chemical or catalytic reaction, a constant flow velocity is required in the tank. This paper shows how gas distribution plates for crosswise flow tanks or catalysts with a differential cross section distribution can be calculated and designed for the flow‐through area, which nearly ensure a constant flow velocity without an increase of the flow resistance.     

Entwurf und Betrieb eines Rohrreaktors mit enger Verweilzeitverteilung

In process engineering the residence time is an important design parameter, and a narrow residence time distribution is advantageous to avoid possible by-products in complex chemical reactions. A good radial mixing with low axial dispersion provides a narrow residence time distribution in a tube reactor. The axial dispersion of laminar flow in a straight tube is very high and generates a wide residence time distribution. However, secondary flows improve the radial mixing, which are investigated in this paper for curved tube reactors. Design notes for good radial mixing and geometric designs of tube reactors with baffles are presented.