Modeling of Agave Salmiana bagasse conversion by hydrothermal carbonization (HTC) for solid fuel combustion using surface response methodology
Abstract
Hydrothermal carbonization (HTC) of Agave Salmiana bagasse was investigate to assess
the potential of hydrochar as an energy resource. The effect of operating conditions on the mass yield
and the energy quality of hydrochar was examined by varying the temperature and the holding time
over the ranges of 180–250 ℃ (T) and 0–60 min (t), respectively. These parameters were screened
using the response surface methodology through a Doehlert design. Performances of HTC were
assessed on the basis of the hydrochar mass yield higher heating value ultimate and proximate analyses.
In the studied domain, the modeling results indicated that the hydrochar mass yield varies between 45%
and 86% and higher heating valuesfrom18 and 23 MJ.kg-1, which is similar to that of peat. In addition,
the volatile matter and fixed carbon fractions of hydrochars ranged from 54 to 80% and between 12
and 36%, respectively. Energy yield modeling indicated that the mass yield is the most influent
parameter. The maximal energy yield value was obtained at 180 ℃ with time equal to 0 min. Globally,
the evolution of H/C ratio is amplified for temperatures greater than 215 ℃ by increasing the holding
time from 30 to 60 min. For O/C ratio the maximal variation is below these conditions. It is concluded
that increased hydrothermal carbonization conditions favor dehydration reactions, while
decarboxylation reactions are favored in mild HTC conditions. The combustion characteristics such as
ignition peak and burnout temperatures were significantly modified for hydrochars. The model results indicated that lowest ignition and peak temperature values are obtained at both low-temperature and
low-holding time, and high-temperature and high-holding time zones. An increase in the burnout
temperature was correlated with the increase of the fixed carbon content in hydrochars.