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.
Aalto

Development of Vapour Liquid Equilibrium Calculation Methods for Chemical Engineering Design

Juha-Pekka Pokki

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 KE 2 at Helsinki University of Technology (Espoo, Finland) on the 26th of November, 2004, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7421-3)   [395 KB]
Dissertation is also available in print (ISBN 951-22-7377-2)

Abstract

This thesis deals with the development of computational methods for vapour liquid equilibrium (VLE) and volumetric properties. The VLE in this thesis can be divided into the low- and medium-pressure VLE with an experimental part and into the high-pressure VLE with a modelling and simulation part. The volumetric properties in this thesis deal with the extension of the model for compressed liquid densities.

At low-pressure VLE, the emphasis was on the optimisation of model parameters. Two apparatus were built, a circulation still and an automated total pressure apparatus for the vapour liquid equilibrium measurements. The measurements were correlated with activity coefficient models for the liquid phase and with equations of state for the vapour phase. A program for correlating the vapour liquid equilibrium was developed. The measurements and VLE models optimised were needed in developing gasoline additives to replace methyl tertiary-butyl ether (MTBE).

At near-critical VLE, the emphasis was on the robustness of the VLE and simulation routines. There was a need for a simulator to find out the dynamics of several vessels and buffer tanks when vessels were in a runaway condition, exposed to fire and imbalance of flows, or all of these events simultaneously. In addition, the operation point near the VLE critical point was of special interest. A dynamic simulator where the vapour and liquid phases were assumed to be in equilibrium was developed. The pressure relieving devices were assumed to be the only devices to control the flow of material. The effect of the pipe network was not included in the simulator.

The temperature range of the model for the compressed liquid density of mixture was extended. The rigorous bubble point pressure and the critical point computed from the cubic equation of state were more consistent with the experimental data than the pseudo-bubble point and pseudo critical point of the original model. The application range of the model was extended at the expense of accuracy, but the extended model was better than a cubic equation of state.

This thesis consists of an overview and of the following 11 publications:

  1. Uusi-Kyyny P., Pokki J.-P., Aittamaa J. and Liukkonen S., 2001. Vapor liquid equilibrium for the binary systems of 2-methyl-2-propanol + 2,4,4-trimethyl-1-pentene at 333 K and 348 K and 2-butanol + 2,4,4-trimethyl-1-pentene at 360 K. Journal of Chemical and Engineering Data 46, number 3, pages 686-691.
  2. Uusi-Kyyny P., Pokki J.-P., Aittamaa J. and Liukkonen S., 2001. Vapor-liquid equilibrium for the binary systems of methanol + 2,4,4-trimethyl-1-pentene at 331 K and 101 kPa and methanol + 2-methoxy-2,4,4-trimethylpentane at 333 K. Journal of Chemical and Engineering Data 46, number 5, pages 1244-1248.
  3. Pokki J.-P., Uusi-Kyyny P., Aittamaa J. and Liukkonen S., 2002. Vapor-liquid equilibrium for the 2-methylpentane + 2-methyl-2-propanol and + 2-butanol systems at 329 K. Journal of Chemical and Engineering Data 47, number 2, pages 371-375.
  4. Pokki J.-P., Řehák K., Kim Y., Matouš J. and Aittamaa J., 2003. Vapor-liquid equilibrium data at 343 K and excess molar enthalpy data at 298 K for the binary systems of ethanol + 2,4,4-trimethyl-1-pentene and 2-propanol + 2,4,4-trimethyl-1-pentene. Journal of Chemical and Engineering Data 48, number 1, pages 75-80.
  5. Uusi-Kyyny P., Pokki J.-P., Laakkonen M., Aittamaa J. and Liukkonen S., 2002. Vapor liquid equilibrium for the binary systems 2-methylpentane + 2-butanol at 329.2 K and n-hexane + 2-butanol at 329.2 and 363.2 K with a static apparatus. Fluid Phase Equilibria 201, number 2, pages 343-358.
  6. Pokki J.-P., Laakkonen M., Uusi-Kyyny P. and Aittamaa J., 2003. Vapour-liquid equilibrium for the cis-2-butene + methanol, + ethanol, + 2-propanol, + 2-butanol and + 2-methyl-2-propanol systems at 337 K. Fluid Phase Equilibria 212, numbers 1-2, pages 129-141.
  7. Uusi-Kyyny P., Pokki J.-P., Aittamaa J. and Multala R., 2003. Vapour-liquid measurements with an automated static total pressure apparatus. 20th European Symposium on Applied Thermodynamics (ESAT 2003). Lahnstein near Koblenz, Germany, 9-12 October 2003.
  8. Pokki J.-P., Aittamaa J. and Keskinen K. I., 2000. Accuracy of vapour-liquid critical points computed from cubic equations of state. High Temperatures – High Pressures 32, number 4, pages 449-459.
  9. Pokki J.-P., Aittamaa J., Keskinen K. I. and Hurme M., 1999. Modelling emergency relief for processes at near critical conditions. Computers and Chemical Engineering (Suppl.) 23, pages S399-S402.
  10. Pokki J.-P., Hurme M. and Aittamaa J., 2001. Dynamic simulation of the behaviour of pressure relief systems. Computers and Chemical Engineering 25, numbers 4-6, pages 793-798.
  11. Pokki J.-P., Aalto M. and Keskinen K. I., 2002. Remarks on computing the density of dense fluids by Aalto–Keskinen model. Fluid Phase Equilibria 194-197, pages 337-351.

Errata of publications 2, 3, 4, 5, 6, 10 and 11

Keywords: volumetric properties, activity coefficient models, equations of state, vessels, critical point

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© 2004 Helsinki University of Technology

Last update 2011-05-26