Flame stability and OH and CH radical emissions from mixtures of natural gas with biomass gasification gas

In this work, a study about laminar premixed flames derived from the combustion of natural gas and producer gas (25 and 50% by volume) mixtures in an atmospheric burner was carried out. The producer gas was obtained from steam gasification process of dealcoholised marc of grape in a small-scale drop-tube gasification pilot plant, this solid fuel being an abundant biomass waste in Spain. These mixtures have different advantages such as replacing fossil fuels with renewable fuels, reducing NOx emissions and other advantages associated with the biomass consumption. The main objectives of this work are to delimitate the stability diagram of the different mixtures, to evaluate the potential of these mixtures to reduce NOx emission and to study the interchangeability of the gas mixtures used. The results obtained show that an increase in the producer gas amount (and therefore in the hydrogen content) makes possible a stable burner operation at leaner conditions, thus leading to lower combustion temperature and NOx emissions. OH and CH radical concentrations were measured by chemiluminescence to confirm the potential to reduce NOx emissions. The Wobbe index results show a possible interchangeability between natural gas and natural gas/producer gas mixtures below 37% vol. of producer gas.