Simulation of the kinetics of iron-containing mineral phases during pulverized coal combustion

In the furnaces with pulverised coal combustion the danger of the slagging exists. In extreme situation the slagging leads to shut down of power plant for cleaning. For this reason the forecast of the slagging is very important. At the IWBT of the Technical university Brunswick the CFD-program-package FLOREAN exists which can simulate fluid flow and combustion process in the furnaces, i.e. the three dimensional velocity, temperature and concentration distributions and the particle-trajectories are calculated. Also the postprocessor TRAMIC (TRAnsformation of the Mineral Components) to the forecast of the slagging is developed. The program TRAMIC calculates the transformation type and unstationary transformation rate of coal minerals along each particle trajectory, i.e. the chemical and physical processes are not in the equilibrium state. A part of the program TRAMIC is the model of transformation of the mineral-phases with iron content, that are presented in this article. A number of real conversions was analysed and a general transformation scheme was established for about 20 mineral-phases with iron content, including chemical equations and equations for the transformation or reaction constants. Each transformation/reaction was described with one basic model, which corresponds to the respective kinetic of the process. The kinetic models were joined to chains. The temperature of gas and the gas composition in the furnace controls the conversion-process of the minerals over miscellaneous paths. The transformations process of the mineral-phases is calculated along the trajectories in the three dimensional velocity-, concentrations- and temperature-field of a furnace. As example the well documented A1-Flame in the IFRF furnace IJmuiden was simulated, to demonstrate the possibility of the forecast of slagging through the linkage of FLOREAN with TRAMIC.