Products and bioenergy from the pyrolysis of rice straw via radio frequency plasma and its kinetics

The radio frequency plasma pyrolysis technology, which can overcome the disadvantages of common pyrolysis methods such as less gas products while significant tar formation, was used for pyrolyzing the biomass waste of rice straw. The experiments were performed at various plateau temperatures of 740, 813, 843 and 880 K with corresponding loading powers of 357, 482, 574 and 664 W, respectively. The corresponding yields of gas products (excluding nitrogen) from rice straw are 30.7, 56.6, 62.5 and 66.5 wt.% with respect to the original dried sample and the corresponding specific heating values gained from gas products are about 4548, 4284, 4469 and 4438 kcal kg^-1, respectively, for the said cases. The corresponding combustible portions remained in the solid residues are about 64.7, 35, 28.2 and 23.5 wt.% with specific heating values of 4106, 4438, 4328 and 4251 kcal kg^-1 with respective to solid residues, while that in the original dried sample is 87.2 wt.% with specific heating value of 4042 kcal kg^-1. The results indicated that the amount of combustibles converted into gas products increases with increasing plateau temperature. The kinetic model employed to describe the pyrolytic conversion of rice straw at constant temperatures agrees well with the experimental data. The best curve fittings render the frequency factor of 5759.5 s^-1, activation energy of 74.29 kJ mol^-1 and reaction order of 0.5. Data and information obtained are useful for the future design and operation of pyrolysis of rice straw via radio frequency plasma. © 2008.