Modélisation de la combustion du gaz naturel par réseaux de réacteurs avec cinétique chimique détaillée

Abstract : In a conscious environmental context, the European legislation forces natural gas power plants to respect emission limits equal to 25 ppmvd for carbon monoxide (CO) and nitrous oxides (NOx). Financial penalties compel the owner to fine tune his machines. A numerical tool is developed as support for operators to find optimal tunings. This tool aims at predicting pollutant emissions accurately (few ppmvd), with a short response time (use on site) and for all configurations (geometry, operating conditions). However, modelling and simulating the formation of minor species in a turbulent reacting flow remains a scientific and numerical challenge due to the large spatial and temporal spectra involved. The solution proposed in this PhD relies on performing CFD computations (Computational Fluid Dynamics) based on simple chemical mechanisms in order to build up a network of 0D reactors which include detailed chemical kinetics. A general methodology is presented for splitting the flow into statistically homogenous zones, which, once connected, form a reactor network. Two reactor network models are defined and include or not turbulent fluctuations (probability density function) as well as residence time distribution in each reactor. Sensitivity studies of NOx emissions to air humidity, fuel flexibility or gas turbine load changes have been performed. Comparison with on-site measurements shows that the models are representative. Finally, a new modelling of the mean chemical source term is provided (lookup table method for the chemical source term and new probability density function) to enable an accurate prediction of NOx emissions directly from CFD computations.
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Submitted on : Wednesday, December 22, 2010 - 4:09:09 PM
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  • HAL Id : tel-00549790, version 1

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Vincent Fichet. Modélisation de la combustion du gaz naturel par réseaux de réacteurs avec cinétique chimique détaillée. Modélisation et simulation. Ecole Centrale Paris, 2008. Français. ⟨tel-00549790⟩

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