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ISBN 9783843906289

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978-3-8439-0628-9, Reihe Verfahrenstechnik

Bojana Borren
Studies on hydrodynamic strategies for intensification of mass transfer in trickle-bed reactors

161 Seiten, Dissertation Technische Universität Dortmund (2012), Softcover, A5

Zusammenfassung / Abstract

Three-phase trickle-bed reactors are inevitable constituents of large scale industrial processes based on gas-liquid reactions on solid catalysts. Due to the large production volumes and their widespread use in various industrial sectors, ranging from petrochemical and chemical plants to wastewater treatment and biochemical manufacturing processes, there is a considerable economic incentive to improve and intensify existing processes. A comprehensive understanding of the interactions between hydrodynamics, mass and heat transfer as well as chemical reactions and finally, the effects on the overall reactor performance is necessary for the evaluation of the promising process intensification techniques. Complex interactions during steady-state and dynamic operation together with numerous parameters that influence the reactor performance imply that the development of a mathematical model represents a suitable approach for thorough analysis.

This work focuses on the investigation of the effects of trickle-bed prewetting strategies on hydrodynamics and mass transfer and the development of a mathematical model capable of predicting steady-state and dynamic reactor behaviour as well as the examination of the reactor performance during hydrogenation of dicyclopentadiene and 2-butyne-1,4-diol.

The prewetting procedures affect reactor hydrodynamics as well as gas-liquid and liquid-solid mass transfer coefficients. In the most favourable case when trickle-to-pulse transition occurs, a large difference in reactor hydrodynamics causes significantly enhanced gas-liquid mass transfer coefficients that are obtained through two prewetting modes. The prewetting modes affect reactor conversion, but the improvement is strongly dependent on the applied operating conditions. Periodic modulation of the liquid flow-rate leads to modest conversion enhancements.

The knowledge regarding the interactions between prewetting, hydrodynamics and mass transfer coefficients is used for the development of a model that is successfully validated against steady-state and dynamic experimental data. The model-based studies have shown that the liquid flow-rate modulation and thus utilisation of mass transfer multiplicities represents a promising strategy for reactor performance enhancement.