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Doctor's Theses (authored and supervised):

L. Benda:
"Advanced Chemical and Thermodynamic Simulation of Kraft Recovery Boilers";
Supervisor, Reviewer: M. Haider, A. Werner, E. Vakkilainen; Institut für Energietechnik und Thermodynamik, 2020; oral examination: 2020-08-27.



English abstract:
This doctoral thesis describes advanced chemical and thermodynamic modeling of modern Kraft Recovery Boilers in pulp industry. In his work a complete Boiler was validated and modeled using commercial engineering software such as AspenPlus, PPSD and FactSage. Purpose of the boiler model is visualization of non or difficultly measurable quantities to form a strong basis for optimization and monitoring. In total this thesis comprises three main parts. Firstly, one basic calculation chapter is dedicated to essential equations for Kraft Recovery Boilers. Special quantities such as effective heating value and combustion air demand are derived and defined based on international standards. In the second part the modeling of Black Liquor as pseudo component is explained. Since Black Liquor contains numerous chemical compounds, which can not all be handled by standard engineering software, an intermediate step called pseudo component is required. The pseudo component comprises same information about mass and energy content but has chemically defined compounds. In the third part, the hearth of the thesis, the simulation and its interfaces are explained. The first simulated element is a complete furnace model including chemical reactions and radiation phenomena. Radiation calculation is assumed to be one-dimensional and without back radiation. Results of the furnace models are heat flux density, temperature and composition profiles depending on furnace height. Further outcomes are ash melting temperatures. The second simulated element is the upper boiler including all heating surfaces and a natural calculation study. This element comprises simulation of all elements such as pipes in natural circulation, water and flue gas side. Chemical compositions of flue gas and ash in the upper boiler are also an outcome of this model. Furthermore, total mass, energy balance and efficiency analysis are executed linking all outputs from used simulation software tools. Part three concludes with validation of the developed model based on comparison of three realistic simulation cases. In total the obtained results are very convincing and the developed boiler model is able to perform live simulation.

Keywords:
Schwarzlaugenkessel, Zellstoffindustrie, chemische und thermodynamische Simulation

Created from the Publication Database of the Vienna University of Technology.