Influence of H2O on NO formation during char oxidation of biomass

Abstract

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Role of CO2 and H2O on NO Formation during Biomass Char Oxidation

“…One explanation for the initially high NO release in H 2 O/O 2 is that char-N is not initially forming NO in the reaction between char-N and H 2 O but instead forming a NO x precursor, such as NH 3 . 22 A result from this is that the heterogeneous NO reduction step is eliminated: the NO x precursor would be oxidized to NO in the boundary layer of the particle, and formed NO cannot be reduced by the char. As a result, the NO release rate is not increasing in H 2 O/O 2 as in CO 2 /O 2 .…”

“…In this study, the NO release only during the char oxidation stage (marked in Figure ) is considered. NH 3 and HCN are not measured during the char conversion stages in these experiments, because the nitrogen species are rapidly oxidized to NO (see, for example, ref ). The starting time of the char conversion have been estimated from the CO analyzer.…”

“…Recently, it was suggested on the basis of density functional theory computations that NO is a primary reaction product in the reaction between char-N and CO 2 . For spruce bark, it has been shown that H 2 O reacts with char-N, forming NH 3 . In many industrial combustion and gasification systems, CO 2 and H 2 O concentrations can be adjusted, for example, via flue gas recirculation.…”

“…21 For spruce bark, it has been shown that H 2 O reacts with char-N, forming NH 3 . 22 In many industrial combustion and gasification systems, CO 2 and H 2 O concentrations can be adjusted, for example, via flue gas recirculation. Consequently, it is crucial to clarify how these gaseous compounds influence the fate of char-N.…”

Investigation of Heterogeneous NO Reduction by Biomass Char and Coal Char Blends in a Microfluidized Bed Reaction Analyzer

“…Compared with a large number of investigations on the homogeneous reaction of NO with biomass/coal volatiles or gasification gases ,− and the investigations on the heterogeneous reaction of NO with biomass char or coal char, − research works on the interaction between NO with biomass char and coal char blends at high temperatures are still limited. Although many studies have focused on co-combustion between biomass and coal, the combustion characteristics and ash formation during this co-combustion − are often concerned and the research on NOx conversion kinetics in the co-combustion is still not deep enough, as it especially lacks important data.…”