A fuel nitrogen conversion model has been superimposed onto the computational fluid dynamics (CFD) model Furnace, The combined model has been applied to seven pulverised coal-fired boilers serving the Australian power industry in order to predict the emission levels of nitric oxide NO in the flue gases. The nitrogen model is comprised of a gas phase reaction system and a char nitrogen gasification step. Two approaches to char N-to-NO conversion were trialled; one taking experimentally measured conversion percentages and the other assuming that NO is the primary nitrogen product from char nitrogen. The furnaces modelled include units with outputs from 120 to 660 MWe having front-wall, opposed and tangential firing systems burning a range of coals. The predictions were good for some configurations but poor for other configurations under the same firing conditions. The CFD model used cannot be regarded as reliable in its current stage of development. The areas of concern exposed in the application of the model for predictive purposes are simulating the flame structure of swirl burners, and establishing the gasification mechanism of char nitrogen. The latter represents the highest area of uncertainty in the simulation. To get good fits with measured values it was necessary to adjust the degree to which NO penetrates the char particles and is reduced to N-2. Further experimental information and an improved char model should rectify this situation within a few years. (C) 2000 Elsevier Science B.V, All rights reserved.