Study on the effect of drying conditions on the pyrolysis properties of rice husk

Abstract

Drying can remove the moisture and volatile fraction from biomass to achieve the purpose of improving the pyrolysis performance of biomass feedstock. In this project, three different drying treatments (blast, vacuum and microwave) were applied to rice husk in order to investigate the effect of drying conditions on the pyrolytic properties of rice husk. Thermogravimetric experiments were performed on the materials at different heating rates (10°C/min, 20 °C/min, 30 °C/min). Then the TG and DTG plots were analyzed, and the kinetic parameters were solved and compared using the FWO method. Experimental studies have shown that the pyrolysis process of rice husk can be divided into three stages, namely the water loss stage, the pyrolysis stage, and the carbonization stage. At the same heating rate, the highest weight loss rate of rice husk was achieved after microwave drying, with a maximum weight loss rate of 97.1% at 20°C/min. In addition, with the increase in temperature rise rate, the characteristic temperature of rice husk of both blast drying and vacuum drying showed a changing trend of increase, and the TG and DTG graphs showed a movement toward the high-temperature side, while the characteristic temperature of rice husk after microwave drying was basically unchanged. The activation energy of all three dried rice husks was calculated by the FWO method to reach the maximum at a conversion rate of 0.6. The average activation energy of rice husks after microwave drying was much greater than that of the other two drying methods, indicating that microwave drying made rice husks more difficult to pyrolyze.