Corn-straw-processed fuels in residential use: Combustion characteristics, kinetics, and pollutant formation mechanisms

This study explored the combustion characteristics, kinetics, pollutant formation, and reduction mechanisms of corn straw (CS)-processed fuels in residential applications. CS was collected to prepare CS briquettes (CSB) and CS charcoal (CSC). Derivative thermogravimetric (DTG) peaks implied that the combustion of CS, CSB, and CSC was dominated by pyrolysis, pyrolysis and char combustion, char combustion, respectively. Briquetting considerably decreased the devolatilization index (D) (66.4 %) and the maximum weight loss rate (DTG_max) (55.0 %); therefore, the CSB exhibited controlled pyrolysis and lower pollutant emissions than CS. Moreover, carbonization led to a considerable reduction in volatile matter (VM) content; thus, CSC exhibited lower pollutant emissions than CS. Both CSB and CSC successfully achieved significant emission reductions compared to CS for SO₂, NO_x, PM_2.5 and its sub-factions include organic carbon (OC), element carbon (EC), polycyclic aromatic hydrocarbons (PAHs), inorganic ions and metals. CSC is a little more effective in most pollutants' reduction, and much more effective in EC reduction, yet less effective in ions reduction compared to CSB. EC emissions positively correlate with VM content (R² = 0.989), which lead to the more remarkable EC reduction in CSC for CSC's much lowered VM content. Overall, A well-designed briquette factory location as well as encouragement of other users besides residents would make it sustainable for the large-scale utilization of corn straw processed fuels.