Effects of heating rate and gas atmosphere on the pyrolysis and combustion characteristics of different crop residues and the kinetics analysis

Abstract

Abstract Efficient utilization of crop residues can help to solve the problem of global resource scarcity. The pyrolysis and combustion characteristics of 40 crop residues and 3 lignocellulosic components in different atmospheres by thermogravimetric analysis were analyzed. The results showed that with the increase of heating rate, the pyrolysis and combustion of cellulose, hemicelluloses, lignin and crop residues shifted to higher temperature zones. Meanwhile, the comprehensive combustibility index increased significantly, indicating that a higher heating rate could intensify and improve the pyrolysis and combustion performances. At the heating rate of 20 °C/min, the variation ranges of ignition temperatures of crop residues in N2, air and O2 were 253–295 °C, 247–275 °C and 245–268 °C, and the variation ranges of burnout temperatures were 555–682 °C, 466–596 °C and 323–357 °C, respectively. The comprehensive combustibility index in O2 was 144.24 × 10−7, which were much higher than those in air and N2. The variation ranges of activation energies of crop residues were 25.52–36.84, 27.96–43.35 and 41.07–69.35 kJ/mol in N2, air and O2 at 20 °C/min, respectively, and the combustion of crop residues in O2 is the most intense. Overall, rape stalk showed the best comprehensive pyrolysis and combustion performance, and rice straw was the poorest.