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An airlift reactor with inverse internal loop (annulus sparged) is investigated with regard to liquid velocity and dispersion coefficient for the purpose of reactor design. To distinguish between the influence of the individual parts of the reactor (downcomer, riser, bottom) on the liquid velocity and mixing, several draft tubes with different geometries and draft tube bottom clearances are successively installed.

lo] Kida, K.; Morimura, S.; Sonoda, Y ; Obe, M.; Kondo, Z: J. Ferm. Bioeng. 69 (1990) S. 354/359. [ll] Borja, R.; Martin, A.; Luque, M.; Durdn, M . M.: Technologia del agua 95 (1992) S. 27/37. [12] Borja, R.; Martin, A.; Luque, M.; Durcin, M . M.: Process Herrn Professor DK Horst Langemann zum 65. Geburtstag Die Bestimmung lokaler Gas-und Feststoffgehalte in turbulenten Dreiphasengemischen ist ein vielfach auftretendes verfahrenstechnisches Problem. In dieser Arbeit wird ein Verfahren beschrieben, diese MeBgroBen on-line und ohne die Entnahme einer Probe zu ermitteln. Hierzu wurde ein handelsiibliches Time-Domain-Reflectometry-(,,TDR-) MeBgerat eingesetzt, mit dem in Kombination mit einer DifferenzdruckmeBmethode die lokalen Gasund Feststoffgehalte in einem Airlift-Schlaufenreaktor gemessen werden konnten. Die Ergebnisse werden mit den Resultaten einer

Airlift loop reactors are useful in many chemical and biotechnological processes where three phase reaction systems are required. One example is biological waste water treatment. In order to enhance biological reaction rates it is often useful to immobilize the bacteria on carrier particles. Knowledge of solid distribution and local gas holdup in those systems is important for calculation of mass and energy transfer or reaction kinetics. For this reason a method has been developed which enables to measure such local phase holdups. The measuring system consists of a time-domain-reflectometry (TDR)-instrument in combination with a pressure difference meter. The method has successfully been applied to determine local axial gas and solid distribution in internal airlift loop reactors, filled with a three phase system consisting of water, air, and polymer particles.