A method of retrieving char oxidation kinetic data from reacting particle trajectories in a novel test facility under oxy combustion conditions

摘要

In this paper, a new method of retrieving char combustion rates is presented. The method is based on an observation that trajectory of a freely falling and reacting char particle in a horizontal laminar flow changes due to change of its mass. Non-burning particles follow straight lines whilst burning particles bend due to mass loss. Since the deviation from the non-reactive particle trajectory depends on the rate of change of mass, it was postulated that recorded trajectories can be used to determine the rate constants of mass loss. An experimental facility was designed and built at the Institute of Thermal Technology, which allows recording reacting particles' trajectories and determining oxidation kinetics. In this procedure a model of a freely falling particle in a laminar horizontal flow was developed. The model comprises a set of ordinary differential equations that predict a particle trajectory for given rate constants. The trajectory predicted by the model is then fitted to the measured trajectories by changing the rate constants. The best fit corresponds to the mean rate constants. The inverse procedure was developed in the MATLAB software. The experimental facility and measurement procedure are briefly described. This is followed by a description of the applied inverse procedure. Measurement results for various O_2/CO_2 mixtures for two polish coal chars are then presented.