Model construction and application for rice husk pyrolysis

The process of biomass continuous pyrolysis is efficient and suitable for industrialization. In the paper, the rice husk pyrolysis model was built and kinetics parameters were obtained based on thermo analysis data of rice husk pyrolyzed at heating rate range from 20 to 40℃/min and final temperature of 800℃. Three stages were included in the process of rice husk pyrolysis: waterloss and pre-pyrolysis, main pyrolysis and carbonization. The stages of waterloss and pre-pyrolysis and main pyrolysis were calculated by the piecewise model. The result showed that the process of waterloss and pre-pyrolys accorded with N-step reaction, while main pyrolysis stage accorded with J-M-A equation. The pyrolysis model was tested in and out of the heating rate range which was used for model building. The verification result showed that the model calculated data was close to the experiment data, the error of the calcuated data was less than 2.35%. So it demonstrated that the pyrolysis model has a wide adaptability, which can provide a theoretical foundation for the design of pyrolysis reactor. A continuous biomass pyrolysis reactor with variable screw pitch had been designed and manufactured based on the model. The rice husk powder pyrolysis on the reactor was studied and it showed that the reactor could run continuously and stably. However, with different calefactive process, the char yields obtained in continuous pyrolysis experiment was lightly different from the calculated and thermo analysis result.