Necessity and Feasibility of 3D Simulations of Steam Cracking Reactors

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• 作者：Pieter A. Reyniers ; Carl M. Schietekat ; David J. Van Cauwenberge ; Laurien A. Vandewalle ; Kevin M. Van Geem ; Guy B. Marin
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2015
• 出版时间：December 16, 2015
• 年：2015
• 卷：54
• 期：49
• 页码：12270-12282
• 全文大小：526K
• ISSN：1520-5045

文摘

Using detailed kinetic models in computational fluid dynamics (CFD) simulations is extremely challenging because of the large number of species that need to be considered and the stiffness of the associated set of differential equations. The high computational cost associated with using a detailed kinetic network in CFD simulations is why one-dimensional simulations are still used, although this leads to substantial differences compared to reference three-dimensional simulations. Therefore, a methodology was developed that allows one to use detailed single-event microkinetic models in CFD simulations by on the fly application of the pseudo-steady-state assumption to the radical reaction intermediates. Depending on the reaction model size, a speedup factor of more than 50 was obtained compared to the standard ANSYS Fluent routines without losing accuracy. As proof of concept, propane steam cracking in a conventional bare reactor and a helicoidally finned reactor was simulated using a reaction model containing 85 species: 41 radicals and 44 transported species. Next to a drastic speedup of the simulations due to the kinetic network reduction technique, significant differences were observed between the bare and the finned reactor in the three-dimensional simulations. In particular, the ethene selectivity is reduced by 0.20% by application of the helicoidally finned reactor. The one-dimensional simulations were not able to correctly predict the selectivity effect of the different reactor geometry.