Evolution of the mass-loss rate during atmospheric and pressurized slow pyrolysis of wheat straw in a bench-scale reactor

Autores

Greco, G; Videgain, M; Di Stasi, C; Gonzalez, B; Manya, JJ

Revista

JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS

Año: 2018 Volumen: 136 Páginas: 18-26

Editor:

ELSEVIER SCIENCE BV

DOI:

10.1016/j.jaap.2018.11.007

Resumen

In the present study, the effects of the absolute pressure (0.1 or 0.5 MPa) and the reactor atmosphere (pure N-2 or a mixture of CO2/N-2) on the pyrolysis behavior of wheat straw pellets (at 500 degrees C) were investigated. The most interesting aspect of this work was the use of a weighing platform (with a maximum capacity of 100 kg and a resolution of 0.5 g) to monitor the real-time mass-loss data for the biomass sample (with an initial mass of 400 g). It was observed that an increased pressure considerably affects the mass-loss profiles during the pyrolysis process, leading to higher devolatilization rates in a shorter period of time. Regardless of the pyrolysis atmosphere, an increase in the absolute pressure led to higher yields of gas at the expense of produced water and condensable organic compounds. This finding could be due to the fact that an increased pressure favors the exothermic secondary reactions of the intermediate volatile organic compounds in both liquid and vapor phases. The switch from pure N-2 to a mixture of CO2 and N-2 at 0.1 MPa also led to a remarkable increase in the yield of produced gas at the expense of the total liquid. This could be mainly due to the promotion of the thermal cracking of the volatile organic compounds at a high partial pressure of CO2, which is also consistent with the measured higher yields of CH4 and CO. The increased yield of CO can also be seen as a direct result of the enhanced reverse Boudouard reaction, which can also explain the much higher specific surface area (and ultra-micropore volume) measured for the biochar produced under the same operating conditions (0.1 MPa and a mixture CO2/N-2 as pyrolysis medium).

Palabras clave

Wheat ; straw ; Pyrolysis ; Biochar ; CO2 ; atmosphere ; Pressure ; Devolatilization ; rate

Afiliación

Manya, JJ (Reprint Author), Univ Zaragoza, Aragon Inst Engn Res I3A, Crta Cuarte S-N, E-22071 Huesca, Spain.
Greco, Gianluca; Videgain, Maria; Di Stasi, Christian; Gonzalez, Belen; Manya, Joan J., Technol Coll Huesca, Huesca, Spain.
Manya, Joan J., Univ Zaragoza, Aragon Inst Engn Res I3A, Crta Cuarte S-N, E-22071 Huesca, Spain.