Study On The Co-pyrolysis Characteristics Of Biomass And Coal

Two commonly available kinds of biomass(rice husk and wood chips) and coal were selected in present study. The pyrolysis and co-pyrolysis performance of biomass and coal were studied by thermogravimetric(TG), and the influence of heating rate and terminal temperature on co-pyrolysis process were analyzed. In addition, using TG-FTIR to study the characteristics of main gaseous product(CO、 CH4、CO2) that released from the co-pyrolysis of corn stalks and coals which at different mixing ratio and discuss the synergetic effects during co-pyrolysis process. The kinetic model of co-pyrolysis was erected and the kinetic parameters were obtained. The structural characteristics of char ware studied by nitrogen isothermal absorption-desorption method.Co-pyrolysis mass lost was large and the main pyrolysis temperature range was increased with the increase of the heating rate. Terminal temperature has little effect on the co-pyrolysis and with the increase of terminal temperature, weight loss rate of mixed sample was increased, but the main co-pyrolysis temperature range unchanged.In a final co-pyrolysis temperature(900℃) and heating rate (25k/min), the DTG2max was increased but the DTG3max and T3max were decreased with increased of mixing ratio. It could be indicated that the main pyrolysis temperature range of biomass and coal can be overlapped partly, and synergetic effects might be existed during co-pyrolysis of biomass and coal.Compared with the theoretical and measured values of CO、CH4、CO2, it can be found that types and mixing ratios of biomass differently effect these gas products, at the same time, the difference between theoretical and measured values, may indicated that the synergetic effects might be existed during co-pyrolysis of biomass and coal.Coats-Redfern integral method was used to analysis the kinetics on the co-pyrolysis process. The study found that this method was not applicable to the entire co-pyrolysis process, the entire process needs to be divided into two main pyrolysis stage, which was I kinetics reaction. From the kinetic results can be seen, with the increased of mixing ratio, the first stage activation energy was decreased, but always lower than the activation energy of pyrolysis of biomass, and the second stage activation energy was gradually reduced, so as can be seen from the view of kinetic, synergetic effects existed during co-pyrolysis.The char were characterized by nitrogen isothermal absorption-desorption method. The specific surface area was increased first and then decreased. Microporous also have similar changes.