Study On The Kinetics And Devolatilization Of Coal Pyrolysis

Coal pyrolysis is an initial process of all major coal conversion, like gasification and combustion, carbonization, therefore, research on pyrolysis is very important for coal conversion process. Based on analysis of coal structure and TG/DTA, TG/MS, Py-FTIR investigation of coal pyrolysis, the kinetics of pyrolysis and the emission of pyrolysis gases were studied on 9 kinds of different rank coals and Huolinhe, Yima coals demineralized by HF/HC1 and extracted by respective and successive ways with five kinds of solvent: CS2, Benzene, CHC13, THF and Pyridine. The main conclusions are as following:(1) The structure and pyrolytic characteristics of different rank coals: The higher rank coals are , the more aromatic hydrogenand aromaticity have they. The higher rank coals lost lower weight and have higher initial pyrolysis temperature, higher temperature at the highest weight loss rate. With increasing of the heating rate, the weight loss unchanges, the characteristic temperatures increase, the highest weight loss rates linearly increase with the heating rate. The apparent activation energies and pre-exponential factors are calculated in the different pyrolysis temperature stages by the first-order raction model. The apparent activation energy reaches the maximum value about Cdaf81% of coal. In the different stages of the same heating rate, the apparent activation energy positively relates to the pre-exponential factor. The higher rank coals have lower heat effect and higher temperature of the endothermic and exothermic peaks, lower content of C2.3 light hydrocarbons, lower content oxides, higher content C6-8 aromatic hydrocarbons than the lower rank coals, and the temperatures of the maximum value of these components are higher than the lower rank coals.(2) The structure and pyrolytic characteristics after demineralization: The demineralization by HF/HC1 can remove 90% minerals, and do not change the main coal structure. Afterdemineralization, Huolinhe and Yima coals gain more weight losses, higher characteristic temperatures, higher highest weight loss rate, higher apparent activation energy in the main pyrolysis stage than raw coal. The content of different components studied are lower than raw coal after demineralization, and the temperatures of the maximum value are lower.(3) The structure and pyrolysis characteristics after extraction: With increasing of the solvent polarity, the extraction yields increase, the successive extraction yields are lower than the respective, and the Pyridine extraction can cause aromaticity higher. In 15 0-900 C, the weight loss amount after extraction are more than the raw coal, and the apparent activation energy of the main pyrolysis stage is close to the raw coal except Pyridine extraction. After extration, yields of the gases are lower than the raw coal but THF extraction.