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Numerical modelling of MILD combustion for coal

2007; Inderscience Publishers; Volume: 7; Issue: 6 Linguagem: Inglês

10.1504/pcfd.2007.014683

1741-5233

Ju Pyo Kim, Uwe Schnell, Günter Scheffknecht, Ali Cemal Benim,

Fire dynamics and safety research

Emissions of nitrogen oxides from coal combustion are a major environmental problem because they have been shown to contribute to the formation of acid rain and photochemical smog. Moderate and Intensive Low oxygen Dilution (MILD) combustion is a promising technology for decreasing pollutant emissions and improving combustion efficiency. A combination of air preheating and fuel dilution with combustion products of low oxygen concentration are the main features of this technique. In the MILD combustion mode, preheated air and fuel are gradually mixed with large amounts of recirculated exhaust gas. The objective of the present work is to investigate the capability of present fuel NO mechanisms for pulverised coal combustion to predict the observed nitrogen oxide levels in MILD combustion mode. For this purpose, knowledge of the fate of coal nitrogen during the combustion process is vital. The interaction between turbulence and chemistry is modelled by an advanced Eddy Dissipation Concept (EDC). The NOx model is used to predict NO profiles that are compared to measurements obtained from semi-industrial scale experiments.