Combustion and pollutant emission characteristics of argan nut shell (ANS) biomass

International audience; This paper presents an experimental study of argan nut shell (ANS) combustion in a lab-scale furnace. Biomass composition, properties and microstructures were determined. Combustion behaviour, fuel burn rate (FBR), pollutants (CO and NOx), modified combustion efficiency (MCE) and ash analysis were investigated. A comparison with wood pellets (WP) complying with the ENplus Standard was performed. The impacts of air flow rate and particle sizes on the combustion characteristics were analysed and discussed using three average ANS particle lengths: 5-8 mm, 10-18 mm and 25-30 mm. The results show that the smallest length of ANS particles induced a higher FBR and a regular distribution of the flame shapes compared to the other sizes and to wood pellets. Furthermore, the combustion temperatures, CO emission and MCE values were improved with the highest air flow rate used. CO emission was strongly affected by the operating conditions while NOx was very low for all selected cases. Elemental ash composition reveals that no ash agglomeration was observed during experiments in terms of alkali index. Moreover, the obtained ash was in the form of powder instead of agglomerated particles. This experimental investigation improves the understanding of the operational characteristics and the combustion effect of ANS biomass.