Pelletization Property Analysis of Raw and Torrefied Corn Stalks for Industrial Application to Achieve Agricultural Waste Conversion

Agricultural waste conversion is of great concern to achieve modernization and industrial development and thus leads to a greener route for a sustainable and circular economy. The treatment of corn stalk for pellet production to realize industrial application is implemented, which is conducive to upgrading fuel properties with better storage and transportation characteristics. The obtained results indicate that torrefaction operation is helpful for pellet density enhancement, with a value of up to larger than 0.74 g cm−3. However, the wear strength and hardness are not good enough compared to raw corn stalk, with values of 4.5–7.5 % and 88 kN–92 kN, respectively. A longer compression duration contributes to a greater work condition and higher relative HHV, which is conducive to energy efficiency improvement. To further evaluate the hygroscopicity and moisture resistance capacity of pelletized corn stalk for fuel properties evaluation, the equilibrium moisture content and contact angle reflect that the enhancement of pressure and compression duration are beneficial for moisture resistance capacity improvement, with the values of less than 3.5 % and higher than 130°. When considering the fuel properties and pelletization cost, compromising on operation conditions should be adopted for optimal operation.