Co-combustion of coal and waste in pulverized coal boiler

A novel reactor reproducing PCB (pulverized coal boiler) environment was used to evaluate the potential of sorbent co-firing and waste co-combustion as cheap retrofitting techniques to reduce SO2 emissions of existing boiler. Several co-feeding tests of coal and CaCO3 and coal and Ca(OH)(2) have been performed for a gas residence time around 0.5 s (4 times shorter than PCB). Results show sulfur emission reduction up to 18% with Ca(OH)(2) injection, and up to 20% with limestone for a Ca/S ratio of 2. Co-firing of a 20% thermal share of a waste derived fuel called ReEF (TM), led to SO2 emissions reduction of around 20%. Co firing of this ReEF (TM) led also to HCI emissions of more than 20 ppm due to the PVC content of the ReEF (TM). In order to describe the gas and particles evolution along the reactor height, a model combining almost 30 kinetic reactions from the literature and without any fitting parameters was developed. The model shows that the ReEF (TM) particles had higher residence time in the furnace than coal and sorbent particles. For the temperature and air injection pattern tested, the model accurately predicted the emissions measured at the exit of the reactor for all the feed compositions. (C) 2015 Elsevier Ltd. All rights reserved.