ISBN 9783843906180

978-3-8439-0618-0, Reihe Verfahrenstechnik

Gerit Niggemann
Modellierung, Simulation und experimentelle Validierung des stationären und dynamischen Verhaltens von Trennwandkolonnen

216 Seiten, Dissertation Technische Universität Hamburg-Harburg (2012), Softcover, A5

Zusammenfassung / Abstract

Distillation is still the most frequently applied unit operation for separating multicomponent mixtures in industry. Dividing-wall columns are a promising separation device in terms of energy efficiency because they are suitable for the complete separation of ternary mixtures in one apparatus. This reduces investment and operating costs and increases the process efficiency significantly.

This study deals with the process dynamics of dividing-wall columns and is an innovative contribution based on extensive theoretical and experimental findings. Up to now, the industry hesitated to build these columns, due to concerns and a lack of knowledge in the field of process dynamics. Within the framework of this validation study fundamental examinations of the steady-state operation, the dynamics around the steady-state operating point and the start-up process are performed in detail.

The theoretical analysis is based on the developed process model, which is capable of describing the physical phenomena in a dividing-wall column. The main item for all experimental examinations is a pilot plant, which was designed, built and operated to separate a ternary mixture of fatty alcohols into high-purity products of ∼99 wt %. In addition, the study focussed on theoretical development and experimental implementation of time-optimal start-up strategies. To achieve this, a dynamic optimization study reveals the minimum required start-up time. Based on this trajectory start-up strategies were developed which track the optimal solution and can be properly implemented. The successful implementation at the pilot plant shows the potential for application in industrial practice. The model validation shows very good agreement between simulation results and experimental data. Furthermore, the process model was effectively compared with experimental data from a production-scale dividing-wall column, emphasizing the validity of the model. Thus, the validated process model serves as a virtual plant and allows for performing cost-efficient analysis. Finally a decentralized temperature control concept based on fundamental practical considerations was developed, implemented and experimentally tested.

To summarize, the experimental and theoretical examinations in this work help to bridge the existing gaps of knowledge in the area of dividing-wall columns. Moreover, the understanding gained from this study will help to increase the acceptance of dividing-wall columns in industry.