Vortex combustion characteristics of mechanoactivated coal-biomass composite fuels

This experimental study investigates the combustion characteristics of mechanoactivated coal-biomass composite fuels (70% Kuznetsk bituminous coal / 30% sawdust) in a vortex combustion chamber. The setup employed a seven-section muffle combustion chamber with optical access, incorporating a two-stage burner with tangential and snail-type swirlers to ensure stable combustion initiation. Three distinct combustion phases were observed: chamber preheating (100 s), stable operation (reaching 1500°C), and natural cooling. Mechanochemical pretreatment significantly improved fuel performance, demonstrating complete O₂ consumption (minimum residual 1.9 vol%) and 70% burnout within the first meter of the chamber. Composite fuels outperformed raw mixtures, exhibiting higher steady-state temperatures (>1400°C across all regimes), reduced ignition delays, and a 30% reduction in activation energy (from 200 to 60 kJ/mol). The technology achieved stable oil-free ignition, with CO₂ peaking at full O₂ depletion while maintaining CO/H₂ emissions below 3%. These results validate mechanoactivation as an effective method for optimizing coal-biomass co-combustion in industrial boilers. Further research is required to refine temperature regimes, excess air ratios, and particle residence times. The study contributes essential data for advancing sustainable combustion systems utilizing renewable biomass resources.