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    Experimental Studies of a Petlyuk Column and Validation of a Non-Equilibrium Stage Model
    (2018-04)
    Egger, Torben
    ;
    Hiller, Christoph
    ;
    Fieg, Georg
    Integrated distillation equipment like the Petlyuk column offers enormous energy-saving potential. However, high complexity and few available experimental data lead to high uncertainty. An integrated approach to reduce this risk is proposed. The first study on the influence of relative volatilities on the process behavior is presented. Comprehensive pilot-plant experiments are displayed for three different component systems of linear alcohols. The experiments are carried out for a wide range of operating conditions. Results show a stable operation and high product purities. Based on the experimental data, a predictive non-equilibrium stage model for column design is validated. Experiment and simulation indicate good agreement.
    Publicationtype: Journal Article
      146
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    Modeling and in-depth analysis of the start-up of dividing-wall columns
    (Elsevier, 2011-07-23)
    Niggemann, Gerit
    ;
    Hiller, Christoph
    ;
    Fieg, Georg
    Saving potentials of up to 30% in capital and operating costs are the driving forces behind the increase in the application of dividing-wall columns in industry. However, a lack of knowledge still exists when dealing with the start-up of dividing-wall columns, which is inherently a strongly nonlinear process. Here, for the first time the start-up of dividing-wall columns is explored, where the starting point is an empty column at ambient conditions. A model is presented which is capable of predicting the dynamic discrete-continuous changes which are characteristic of dividing-wall columns. The proposed process model takes into account the heat transfer across the dividing wall as well as the vapor distribution below the dividing wall. The degree of accuracy of the model is clearly determined by comparing different simplifications, e.g. a constant vapor distribution ratio equal to the steady-state value. The detailed studies were carried out with strict product specifications so that the influence of process parameters could be quantified. The rigorous process model and the obtained simulation results presented in this study provide a promising basis for developing and applying optimal start-up policies for dividing-wall columns.
    Publicationtype: Journal Article
      27
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    Decentralized temperature control of a pilot dividing wall column
    (Elsevier, 2011-02-01)
    Buck, Christina
    ;
    Hiller, Christoph
    ;
    Fieg, Georg
    The technology of dividing wall columns offers to save high amounts of operating and investment cost compared to conventional distillation columns and their configurations. The practical application is still limited due to a lack of experience and high interactions among the process variables. The present work deals with the development and test of a control system for a pilot dividing wall column. Within this, decentralized temperature control systems are designed by a systematic approach. Furthermore, these systems are evaluated concerning the process stability, the providing of defined product purities and the respective requirement of energy in case of disturbances. The focus is on simulative and experimental investigations in order to assure the practicability of the developments. The presented results show the effectiveness of the applied methods.
    Publicationtype: Journal Article
      14
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    Applying model predictive control to dividing wall columns
    (Wiley-VCH, 2011)
    Buck, Christina
    ;
    Hiller, Christoph
    ;
    Fieg, Georg
    The technology of dividing wall columns can offer enormous energy savings compared to common distillation columns and configurations. The technology of model predictive control is also advantageous since such a controller minimizes the future deviation of the predicted controlled variable from the reference point. The practical application of model predictive controllers for dividing wall columns is still limited due to limited experience with high interactions among the process variables. The scope of this work is the development and analysis of a method for the design of model predictive controllers for dividing wall columns. An experimental investigation verifies the practicability of the applied approach. The methods generated are transferable to other applications. Thus, the industrial acceptance of model predictive controllers for dividing wall columns is enhanced. The systematic development and evaluation of a model predictive controller for a dividing wall column is presented. The work is based on both simulative and experimental investigations. The resulting, outstanding controller performance verifies the applied approaches. The methods are transferable to other dividing wall columns. This helps to overcome obstacles associated with the use and control of dividing wall columns. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Publicationtype: Journal Article
      28