Pyrolysis reaction mechanism of typical Chinese agriculture and forest waste pellets at high heating rates based on the photo-thermal TGA

• Published in: Energy (Oxford) Vol. 244; p. 123164
• Main Authors: Song, Gongxiang, Huang, Dexin, Li, Hanjian, Wang, Xuepeng, Ren, Qiangqiang, Jiang, Long, Wang, Yi, Su, Sheng, Hu, Song, Xiang, Jun
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-04-2022; Elsevier BV
• Subjects: Agricultural wastes; Agriculture; Biomass; Cellulose; Forestry wastes; Heating rate; Kinetics; Mass transfer; Photo-thermal; Production characteristics; Pyrolysis; Reaction mechanisms; Reactors; Three dimensional models; Volatiles; Pyrolysis; Photo-thermal; Biomass; Production characteristics; Kinetics
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2022.123164

To investigate gas generation characteristics and the kinetics mechanism of biomass pyrolysis process at fast heating rates, a concentrated Photo-thermal TGA reactor (Pt-TGA) was set up. The reactor was reliable for the study of thermochemical kinetics because the average difference between the commercial TGA and Pt-TGA curves for the cellulose pyrolysis process was only 2.1%. Four kinds of typical Chinese forest and agriculture wastes were selected to study the pyrolysis process in Pt-TGA. At higher heating rates, the volatiles from pyrolysis eventually formed more non-condensable gases because of inner-particle secondary reactions. In the range of 450–850 °C, with the temperature rising, the production of H2 increased, and the highest H2 yield reached 279 mL/g. Combined with kinetic analysis, with the increase of heating rate, heat and mass transfer had a more prominent effect on the pyrolysis of biomass particles, and the reactions were controlled by three-dimensional diffusion model.
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•Established a reliable photo-thermal TGA with a heating rate of up to 500 °C/min.•The main gas yields were strongly correlated with the pore structure of char.•The H2 yield of rice straw can reach 279 mL/g with a heating rate of 500 °C/min.•The kinetic model changed to a three-dimensional diffusion model at 200 °C/min.•Inner-particle secondary reactions significantly affected the conversion of tar.