A predictive scheme based on CCSEM fly ash data and computational fluid dynamics has been developed to predict the ash deposition and its effects on the walls of pulverized fuel―fired combustion systems. During combustion, the inorganic constituents of coal are transformed into products which may transfer to combustor walls and form deposits which restrict heat transfer. Traditional approaches to the prediction of the deposition behavior of a coal usually involve the use of empirical indices and American Society for Testing and Materials ash fusion temperatures based on coal and ash chemistry and the particle size distribution. These approaches normally give misleading results and are hence accepted as being valid only in qualitative terms. The improved accuracy of the present treatment is based on the inclusion of the effects of both ash chemistry and operating conditions on ash deposits and also takes into account the effect of the association of minerals within the coal matrix. The model also predicts the consequential effect of these deposits on the heat transfer characteristics of the boiler. The predicted results display conformity with the experimental results taken from a large 0.5 MW laboratory pulverized fuel―fired combustor.
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