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Large eddy simulation of thermal cracking in petroleum industry

Zhu, Manqi. Large eddy simulation of thermal cracking in petroleum industry. PhD, Institut National Polytechnique de Toulouse, 2015

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Official URL: http://ethesis.inp-toulouse.fr/archive/00003062/

Abstract

To improve the efficiency of thermal-cracking processes, and to reduce the coking phenomena due to high wall temperature, the use of ribbed tubes is an interesting technique as it allows better mixing and heat transfer. However it also induces significant increase in pressure loss. The complexity of the turbulent flow, the chemical system, and the chemistry-turbulence interaction makes it difficult to estimate a priori the real loss of ribbed tubes in terms of selectivity. Experiments combining turbulence, heat transfer and chemistry are very rare in laboratories and too costly at the industrial scale. In this work, Wall-Resolved Large Eddy Simulation (WRLES) is used to study non-reacting and reacting flows in both smooth and ribbed tubes, to show the impact of the ribs on turbulence and chemistry. Simulations were performed with the code AVBP, which solves the compressible Navier-Stokes equations for turbulent flows, using reduced chemistry scheme of ethane and butane cracking for reacting cases. Special effort was devoted to the wall flow, which is analyzed in detail and compared for both geometries, providing useful information for further development of roughness-type wall models. The impact of grid resolution and numerical scheme is also discussed, to find the best trade-off between computational cost and accuracy for industrial application. Results investigate and analyze the turbulent flow structures, as well as the effect of heat transfer efficiency and mixing on the chemical process in both smooth and ribbed tubes. Pressure loss, heat transfer and chemical conversion are finally compared.

Item Type:PhD Thesis
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Laboratory name:
Research Director:
Cuenot, Bénédicte and Riber, Eleonore
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Deposited By: admin admin
Deposited On:17 Jul 2015 21:58

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