RDF pyrolysis by TG-FTIR and Py-GC/MS and combustion in a double furnaces reactor

With the increasing depletion of fossil energy, the refuse-derived fuel (RDF) as an unavoidable by-product of human activities has been used as an alternative fuel in the precalciner cement kilns. Since the RDF combustion also brings the problems of NOx pollution, it is quite important to find ways to lower the NOx emission during RDF combustion in the precalciner. The pyrolysis characteristics and products of RDF were studied by TG-FTIR and Py-GC/MS. From TG-FITR and Py-GC/MS tests, various carboxylic acids and alkenes formed with NOx released at the RDF pyrolysis process at 200–550 °C. By simulating the temperature (700 °C, 800 °C and 900 °C) and O₂ (12%, 14%, 16%, 18% and 21%) environment of the precalciner using a double furnaces reactor, the combustion processes and NOx formation characteristics of RDF combustion were studied. The results showed that the volatile-N was the dominant reactant source of fuel NOx during RDF combustion. The fuel-N conversion and NOx emission yield showed a continuous decreasing trend with temperature increasing from 700 to 900 °C. The fuel-N conversion and NOx emission yield showed a slight increasing trend with the oxygen concentration increase, and the optimum oxygen concentration for RDF combustion was 14%. In this study, the optimum temperature was 900 °C and oxygen concentration was 14% for de-NOx in the precalciner.