takes place at low temperatures is an indication that these
materials would be instantaneously ignited, when they are
exposed to the high furnace temperatures. A deciding factor
here is the moisture content, which, although it is low for
most residues, can be high for some residues, e.g. bagasse.
High moisture contents have been found to increase the
devolatilization time [12–14]. For dry residues, in addition
to the expected immediate ignition and the high volatile
matter contents, the volatiles consist mainly of the combustibles—
CO, H2, CxHy. These factors together indicate that
the combustion of the volatiles would be the dominant step
during the combustion of agricultural residues and related
biomass. Kaeferstein et al. [31] followed the combustion
process of biomass during batch experiments in a bubbling
fluidized bed using oxygen concentration profiles measured
directly over the bed with solid electrolyte sensor probes.
They observed that for the combustion of the biomass there
was a rapid consumption of oxygen, which took place in one
phase, whereas, for coal, the oxygen consumption profile
exhibited two regions characterizing a short phase for volatile
combustion and a long char combustion phase. The
combustion of the biomass was almost complete after the
completion of volatile combustion. Analysis of heat distribution
during the combustion of wood chips and straw
showed that over 67% of their calorific values were released
through the combustion of the volatiles [11]. Consequently,
it may therefore be expected that during biomass combustion
significant combustion and heat release would take
place near the point where the particles devolatilize.