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Characteristics of Biomass Devolatilization and in Situ Char Gasification Tested by the Non-Isothermal Method
journal contribution
posted on 2019-09-19, 13:35 authored by Xi Zeng, Kaito Kahara, Yasuaki Ueki, Ryo Yoshiie, Guangwen Xu, Ichiro NaruseThis work examined
the reaction behavior and kinetics of in situ
char gasification and the corresponding biomass devolatilization by
TGA based on the non-isothermal method. Four kinds of devolatilization
atmosphere (N2, N2+CO2 (10%), N2+CO2 (50%), N2+steam (10%)), three kinds
of gasification atmosphere (N2+CO2 (10%), N2+CO2 (50%), N2+steam (10%)), and different
heating rates (5, 10, 20, 30, 40 K/min) were adopted. With the increase
of heating rate in each atmosphere for biomass devolatilization or
char gasification, the typical reaction temperatures, including TBD‑max, TCG‑i, and TCG‑max, increased obviously
due to the delayed effect. At a given heating rate, the adopted devolatilization
atmospheres displayed very weak influence on the volatiles release
behavior and kinetics, even for the CO2 content of 50%,
but had an obvious influence on the char property. The volume reaction
model and shrinking core reaction model were suitable to describe
the behaviors of biomass devolatilization and char gasification, respectively.
Compared to biomass devolatilization, the reaction atmosphere had
a remarkable effect on char gasification, especially in the curve
shape of reaction rate and kinetic parameters. For the in situ char
gasification, the calculated activation energy (E) in the steam atmosphere was much lower than that in the CO2 atmosphere. While for the char gasification in the steam
atmosphere, the E of ex situ char was higher than
that of in situ char, indicating the necessity of adopting the in
situ char for the char gasification research.