Combustion kinetics in the modeling of large, pulverized fuel furnaces: A numerical experiment in sensitivity

A mathematical model of combustion in a utility type of pulverized, coal fired furnace is developed by dividing the furnace into a number of isothermal zones. The method dovetails the combustion rate data available for single char particles with a gas flow pattern to predict local combustion heat release rates and local radiation absorption coefficients, which are used as input to a zoned heat transfer model. The furnace heat transfer is shown to be insensitive to combustion related parameters such as coal rank and coal fineness. For carbon in ash, local gas temperature, and to a lesser extent local heat flux, significant variations are predicted. It is concluded that for calculation of radiative heat transfer, combustion data are adequate. Further research activity on ignition and combustion stability, together with the radiative properties of fly ash, is recommended.