Feasibility and Characteristics Study on Direct Ignition of High-Temperature Biomass Gasification Syngas with Ambient Air

To advance the engineering application of the fusion decoupling combustion technology previously proposed by our research group, this work focuses on its second stage—the high-temperature syngas combustion stage—and specifically addresses the critical issue of whether high-temperature gasified syngas can achieve direct and stable ignition when mixed with ambient air. For this purpose, a high-temperature syngas combustion experimental system was established, utilizing syngas that simulates the composition of biomass gasification products as the research subject. A systematic investigation was carried out to explore the influence patterns of syngas temperature and key components on the ignition limits, which are characterized by the lower and upper limits of the excess air coefficient (λmin and λmax). The results indicate that increasing the syngas temperature significantly broadens the ignition limits: λmin decreased from 0.73 to 0.59, while λmax increased simultaneously, primarily due to accelerated reaction kinetics and the contribution of high-temperature sensible heat. An increase in H2 content significantly expands the ignition range, whereas an increase in CO content narrows the limits, reflecting the opposing roles of these two components in terms of reactivity. Both diluent components, CO2 and N2, increase λmin; however, N2 exhibits a more pronounced inhibitory effect due to its higher volumetric heat capacity and greater thermal inertia. This study confirms the feasibility of direct ignition between high-temperature gasification syngas and ambient air, providing important experimental evidence for the engineering application of the fusion decoupling combustion process.