A comparative study on characteristics of sulfur and nitrogen transformation and gaseous emission for combustion of bituminous coal and char

The characteristics of sulfur and nitrogen transformation and the emissions' comparison of sulfurous and nitrogenous gas were investigated using SEM, XPS, TG-FTIR and TG-gas analyzer during the combustion process of Shenmu bituminous coal (SM coal) and its char. SEM indicated that porosity and specific surface area of char were enlarged after coal pyrolysis and a large amount of space could be provided for the oxidation reaction of various sulfur species with oxide during the combustion process. The sulfur and nitrogen species of the two samples analyzed by XPS showed that, pyritic sulfur, organic sulfide sulfur, sulfone and sulfoxide sulfur in coal were partly transformed to thiophenic sulfur and sulfate sulfur in the pyrolysis of coal, and the total sulfur content in char was reduced. Besides, the sulfur and nitrogen species' changes in SM coal, char and the ashes determined by XPS showed that sulfur fixation effect was enhanced in the presence of calcium oxide during combustion. The component analysis of the gas during combustion via TG-FTIR indicated that SO2 and NO2 began to escape at 300 degrees C and reached maximum at about 1100 degrees C, by contrast, the emissions of SO2 and NO2 of char were below that of SM coal throughout the whole combustion process. The wide range of TG-gas analyzer analysis revealed that the SO2 and NOx emissions of SM coal were 2.51 and 1.71 times as much as char burning, respectively. (C) 2018 The Authors. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.