Statische Mischer und ihre Anwendung

Static mixers and their applications . Static mixers are generally made up of similar, fixed mixing units installed at right angles to each other in series along a tube or a channel. The energy of mixing is extracted from the flow. Twelve different units are presented. The mixing effect in static mixers under conditions of laminar flow is accomplished either by specially designed feed systems, by cutting and twisting, by displacement and distortion, or by separation and expansion. Depending upon the mixer, very different lengths are required to achieve the same degree of homogeneity. Compared with an empty tube, the pressure drop in static mixers is some 7-to 200-fold greater for laminar flow and 100- to 600-fold greater for turbulent flow. Static mixers are employed in all areas of chemical engineering for homogenization, for reduction of the resisdence-time spectrum, and for heat exchange. Since maintenance and wear are negligible, since incorporation frequently requires no extra space, and since they can be used over wide ranges of viscosity, static mixers are being increasingly employed in continuous processes.     

Einfluss mikrostrukturierter statischer Mischer auf den Gas/Flüssig‐Stofftransport in einem engen Rechteckkanal

Experimental results of the volumetric mass transfer coefficient k_La_Ph in a microstructured rectangular channel (Miprowa®) with static mixers are presented. The physical absorption of CO₂ in H₂O was identified as suitable measuring method. The results include a gas‐liquid flow map and the identification of different flow regimes as well as first systematic measurements of the k_La_Ph value as a function of various process settings like gas and liquid flow rate and gas holdup. A first comparison of Miprowa® with established gas‐liquid contact devices like stirred tank and bubble column is given.     

Auslegung von Granulierteller und Granuliertrommel

Disign of granulating plates and granulating drums. Equations relating mechanical and geometrical parameters have been derived for use in calculating the power requirements of granulating plates and granulating drums. An attempt is made to maintain the same product properties, especially the porosity and size of the agglomerates, on scale-up of the granulating equipment. This condition considerably limits the possible operational parameters. In order to define the operating conditions on scaling-up from model experiments, their influences are described in terms of theoretical models and empirical results. The utility of the expressions derived is illustrated using the design of a granulation plate as example.     

Auslegung und Optimierung von hybriden Trennverfahren

Design and Optimization of Hybrid Separation Processes Hybrid separation processes are defined as the combination of at least two different unit operations in different apparatus which contribute to the separation task. Hybrid processes are used for difficult separations, e.g., close‐boiling mixtures and azeotropes, if a single unit operation, e.g., distillation, membranes, extraction, crystallization or chromatography, is not efficient or even not feasible. Because of the structure of a hybrid process which implies two or more unit operations and recycle streams, the design is not straightforward and therefore subject of today's research. In this work general criteria for such a consistent design method are described and a design approach for hybrid separation processes is presented. It bases on rigorous modeling of the unit operations and simultaneous multivariable optimization. The approach feasibility is demonstrated by the separation of an isomer mixture.     

Richtlinien für Einsatz,Auslegung und Betrieb von Fallfilmrohrverdampfern zur Aufarbeitung thermisch- sowie oxidationsempfindlicher hochsiedender Flüssigkeitsgemische im Vakuum

Guidelines for Application, Lay-Out and Operation of Falling Film Tubular Evaporators for Processing under Vacuum high Boiling Liquid Mixtures which are Sensitive against Local Overheating and Oxidation For the beginning there are discussed the different application possibilities and their limitations for falling film tubular evaporators running with co- and counter-current direction of both stream line phases - the down flowing liquid filmstream on the heated inner pipe wall and out of the latter the by film-evaporation generated vapour stream - for handling mixtures sensitive against heat and oxidation at high evaporation temperatures and low working pressures. Today large quantities for heat have to be transferred for preheating, evaporation and because of hte always needed high working temperature for balancing the always not insignificant heat losses. The best economical way to do this is by using falling film tubular heaters because of hte thermal and oxidative sensitivity of such high boiling, high molecular weight and mostly also strongly unsaturated compounds the following points are of special importance during the evaporation in such installation: 1. Tightness against leakages, 2. Full covering of the evaporator heating surface over the length by the heated falling liquid film, 3. Temperature difference against heating medium. By means of examples out of the industries of vegetable oils and fatty acids it will be shown how to come the industries of vegetable oils and fatty acids it will be shown how ot come for the industrial practice by taking in mind all these aspects to optimum solutions. They have for the addressed problems of distilling high boiling thermal sensitive mixtures at low working pressures above the treated examples general importance. On this reason the for such cases restrained working conditions are intensive discussed for the liquid film to be formed as well as for the vapour stream to be ascended out of it by evaporation. To this belongs also its comparison with the results of new theoretical derivations for falling film tubular evaporators.     

Phasengleichgewichtsmodelle zur Synthese und Auslegung von Trennprozessen

Phase Equilibrium Models in the Synthesis and Design of Separation Processes. While approximately 20 years ago the design of separation processes required expensive and time consuming experiments, modern thermodynamic models nowadays allow a reliable prediction of the phase equilibrium behavior of multicomponent systems using binary data alone. If binary data are not available, group contribution methods can be applied to predict the real behavior. These methods have been developed for the prediction of vapor-liquid equilibria. The range of application and the reliability of these models were improved by modification of the model, definition of new main groups and introduction of temperature dependent parameters. Especially promising models arise on utilising g^E-mixing rules in cubic equations of state. These models can be applied for the calculation and prediction of phase equilibria of strongly polar systems, including supercritical compounds. At the same time these models allow the calculation of densities, thermodynamic properties, etc.