The distribution of the nitrogen between the volatiles and
the remaining char is roughly proportional to the volatile
matter in the fuel. Arsenault et al. [27] pyrolysed straw
(0.4 wt% N) and stover (2.8 wt% N) at around 7508C and
found that the char formed was enriched with nitrogen (1.8
and 3.1 wt% N for straw and stoker, respectively). A
material balance for stover (77 wt% volatile), for example,
showed that 56% of the nitrogen was released with the
volatiles whereas 44% remained with the char. From the
pyrolysis of wood (90 wt% volatiles), it was reported that
80% of the nitrogen was released with volatiles and 20%
remained with the char [59]. For coffee (mbuni) husks, the
distribution of nitrogen between the volatiles and char
ranged from 50 to 68%, as the temperature was increased
from 500 to 9008C (Table 8).
Another point of consideration during the combustion of
the agricultural residues with respect to NOx and N2O
emissions, is the catalytic effect of the char and ash on the
formation and reduction of NOx and N2O. The net concentrations
of NO and N2O in the flue gas of a furnace are a
function of the homogenous gas phase reactions, the heterogeneously
catalysed reactions and the gas/solid phase reactions.
Char, for example, provides a catalytic surface for the
gas phase NO reduction by CO, which is estimated to
account for about 50% of the NO reduction formed at
primary stage during bituminous coal combustion [56].
Further, char is also very effective for the catalytic reduction
of N2O as well as for direct reduction of N2O [60]. In the
The distribution of the nitrogen between the volatiles andthe remaining char is roughly proportional to the volatilematter in the fuel. Arsenault et al. [27] pyrolysed straw(0.4 wt% N) and stover (2.8 wt% N) at around 7508C andfound that the char formed was enriched with nitrogen (1.8and 3.1 wt% N for straw and stoker, respectively). Amaterial balance for stover (77 wt% volatile), for example,showed that 56% of the nitrogen was released with thevolatiles whereas 44% remained with the char. From thepyrolysis of wood (90 wt% volatiles), it was reported that80% of the nitrogen was released with volatiles and 20%remained with the char [59]. For coffee (mbuni) husks, thedistribution of nitrogen between the volatiles and charranged from 50 to 68%, as the temperature was increasedfrom 500 to 9008C (Table 8).Another point of consideration during the combustion ofthe agricultural residues with respect to NOx and N2Oemissions, is the catalytic effect of the char and ash on theformation and reduction of NOx and N2O. The net concentrationsof NO and N2O in the flue gas of a furnace are afunction of the homogenous gas phase reactions, the heterogeneouslycatalysed reactions and the gas/solid phase reactions.Char, for example, provides a catalytic surface for thegas phase NO reduction by CO, which is estimated toaccount for about 50% of the NO reduction formed atprimary stage during bituminous coal combustion [56].Further, char is also very effective for the catalytic reduction
of N2O as well as for direct reduction of N2O [60]. In the
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