The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Modelling and Simulation of Process Configurations Combining Distillation and Reaction

Kaj Jakobsson

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Auditorium KE2 at Helsinki University of Technology (Espoo, Finland) on the 21st of January, 2005, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7564-3)   [1074 KB]
Dissertation is also available in print (ISBN 951-22-7459-0)

Abstract

Process intensification refers to technologies and strategies that enable simpler and more efficient processes compared to conventional processes. Some features of such intensified processes are less recycle streams, reduced need for waste handling and lower investment and operating costs compared to conventional processes. One way of doing this is by making two or more process steps simultaneously and not one after another as it is traditionally done. In this work two such approaches, reactive distillation (RD) and the side reactor configuration (SRC), are studied. RD combines chemical reaction and distillation into a single process unit. In SRC a liquid stream rich in reagents is withdrawn from the distillation and fed into a side reactor. The reactor effluent is returned back into the same column. The final product is then obtained from the distillation column just as in RD processes.

Two models for simulation and design of processes combining reaction and distillation were developed. The first model is for the reactive distillation process. The modelling approach is based on a direct account of the diffusion with multi-component interaction effects, reaction kinetics, and heat transport. The model includes mass transfer in the film region, a catalyst efficiency determination based on the mass transfer inside the catalyst, and hydrodynamic models for reactive trays. This model was successfully tested against experiments from a pilot scale unit.

A new reactive distillation process for producing 2-methoxy-2,4,4-trimethyl pentane is discussed.

The other model is for the Side Reactor Concept (SRC). The model of the distillation column is derived from the mass and energy balances, equilibrium, and summation relations of a stage in a reactive distillation column. Rigorously calculated Murphree multi-component efficiencies are included to account for non-ideality of the stages. This model also includes a series of continuously stirred tank reactors (CSTR) representing the side reactor stage. Co-current flow and gas and liquid phases and heterogeneous catalyst are allowed in the reactor.

The use of SRC and RD is discussed in two case studies, in the production of TAME and isooctene. The study showed that SRC is a potential process option, especially because the reactor conditions can be optimised to improve the performance of the process.

This thesis consists of an overview and of the following 7 publications:

  1. Kenig, E. Y., Pyhälahti, A., Jakobsson, K., Górak, A., Aittamaa, J., and Sundmacher, K., 2004. Advanced rate-based simulation tool for reactive distillation. AIChE Journal 50, number 2, pages 322-342.
  2. Kenig, E., Jakobsson, K., Banik, P., Aittamaa, J., Górak, A., Koskinen, M., and Wettmann, P., 1999. An integrated tool for synthesis and design of reactive distillation. Chemical Engineering Science 54, pages 1347-1352.
  3. Jakobsson, K., Pyhälahti, A., Pakkanen, S., Keskinen, K., and Aittamaa, J., 2002. Modelling of a side reactor configuration combining reaction and distillation. Chemical Engineering Science 57, pages 1521-1524.
  4. Pyhälahti, A., and Jakobsson, K., 2003. Rate-based mixed-pool model of a reactive distillation column. Industrial & Engineering Chemistry Research 42, number 24, pages 6188-6195.
  5. Ouni, T., Jakobsson, K., Pyhälahti, A., and Aittamaa, J., 2004. Enhancing productivity of side reactor configuration through optimizing the reaction conditions. Chemical Engineering Research and Design 82, number A2, pages 167-174.
  6. Rihko-Struckmann, L. K., Karinen, R. S., Krause, A. O. I., Jakobsson, K., and Aittamaa, J. R., 2004. Process configurations for the production of the 2-methoxy-2,4,4-trimethylpentane – a novel gasoline oxygenate. Chemical Engineering and Processing 43, pages 57-65.
  7. Jakobsson, K., Hasanen, A., and Aittamaa, J., 2004. Modelling of a countercurrent hydrogenation process. Chemical Engineering Research and Design 82, number A2, pages 203-207.

Keywords: reactive distillation, rate-based approach, side reactor, methyl acetate, MTBE, TAME, diisobutylene, 2-methoxy-2,4,4-trimethyl pentane

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© 2005 Helsinki University of Technology

Last update 2011-05-26