Modelling of Cyclic Combustion of Coal

The cyclic combustion of coal results from the mevement of a granular material in a flow contour of the furnace with a circulating fluidised bed (CFB): combustion chamber, cyclone, loop system [1]. It can be stated, on the basis of observation of combustion in CFB, that the coal particles, after introducing into a loop system, break the combustion process due to the deficiency of oxygen. Continuation of the combustion takes place after re-input of the coal into the combustion chamber. In such a way the combustion of the coal particles becomes a cyclic process in CFB conditions. The above process relies on multiple heating, ignition, combustion and extinguishing. The results of theoretical and experimental investigations, related to the circular combustion of char particles, are presented in this paper. Elaborated mathematical model allows the wide analysis of combustion in CFB. It enables the prognosis of the combustion course during cyclic interruptions of process and repeated firing up of fuel particles at different intervals of time. It was stated that the cyclic character of the process leads to significant extension of real time combustion of the coal particle.