Influence of Coal Properties on Emissions of Nitrous Oxides and Nitric Oxides

Grey System Theory is applied to study the influence of the coal properties on the emissions of nitric oxides from fluidized bed coal combustion. Grey correlation coefficients for the emissions of nitrous oxides and nitric oxides in relation to the contents of nitrogen and carbon, fixed carbon, volatile matter, nitrogen fractions in char, and volatile, and the O/N ratio, fuel ratio, etc., are calculated. A large correlation coefficient of coal property means that the emission of nitrous oxides and nitric oxides is in close relation with the relevant property, in other words, the relevant coal property is the main affecting factor for nitrous oxides and nitric oxides formations. The calculation results show that the N2O emission is determined mainly by the nitrogen carbon content, fixed carbon, and the nitrogen fraction in char. While the carbon content, fixed carbon, nitrogen fraction in char mainly influence the NO x emission and nitrogen and hydrogen contents, it suggests that combustion of high rank coal with high nitrogen content in fluidized bed emits more nitrous oxides and nitric oxides. The O/N and fuel ratios are not important for emissions of nitrous oxides and nitric oxides compared with other factors. And the results are in agreement with experimental data.