Uncertainty quantification of fuel variability effects on high hydrogen content syngas combustion

Abstract

Fuel variability effects on high hydrogen content syngas combustion physicochemical properties and NOx emission characteristics are investigated invoking polynomial chaos expansion based uncertainty quantification. The focus is put on providing an in-depth understanding of fuel variability effect under very lean conditions, i.e., near lean blowout limit. It is found that leaner combustion of syngas leads to higher flame speed fluctuation. Under 1.5% small fluctuations in species concentration of syngas fuels, a maximum of 5% fluctuation of flame speed is observed at equivalence ratio of 0.45 for H60CO30 (60%H2 + 30%CO), while the lowest fluctuation is observed near equivalence ratio of 0.8 for the cases considered. Meanwhile, maximum NO concentration fluctuation of 8.3% and NO2 concentration fluctuation of 6.5% are observed at very lean conditions. Uncertainty analyses show that on one hand, hydrogen always has the highest contribution to flame speed variation followed by carbon monoxide, carbon dioxide, and methane. On the other hand, carbon monoxide is found to have the highest contribution to variation of flame temperature, followed by hydrogen, carbon dioxide, and methane. The quantified sensitivity information reported in present study can be used to guide targeted uncertainty reduction from syngas upstream gasification process.