Optimisation of downdraft gasifier in biomass-fuelled power generation system: Experimental analysis and chemical kinetics modelling with tar cracking

The electricity supply challenges faced by remote areas and temporary facilities must be addressed. As such, a biomass-fuelled power-generation system was developed that harnesses the biosyngas produced via biomass gasification to fuel a Stirling generator. Experimental and numerical methods were employed to optimise the gasification performance of the downdraft gasifier in the system, focusing on the following key parameters: gasification equivalent ratio (GER), steam-to-biomass ratio (S/B), oxygen-to-biomass ratio (O/B), and moisture content. The key results revealed that a GER of 0.32 yielded the highest syngas low heating value (LHV) of 4.82 MJ/m3, whereas a GER of 0.36 maximised power generation at 1.19 W/s, achieving an effective thermal power of 7999.96 W. The results of a sensitivity analysis revealed the impact of these parameters. The optimal ranges for maximising the biosyngas LHV were a GER of 0.24–0.32, an S/B 0.0–0.2, an O/B 0.0–0.1, and a 5–10 % moisture content. A novel chemical kinetics model incorporating tar cracking increased the accuracy of gasification analysis and predicted tar content. This paper presents an innovative approach for optimising biomass gasification for power generation, offering practical guidelines and advancing ecofriendly energy technologies. •An equivalent ratio of 0.32 achieves a maximum low heating value of 4.82 MJ/m3.•Power generation rate peaks at 1.19 W/s at a gasification equivalent ratio of 0.36.•Sensitivity analysis reveals key operational impacts on syngas quality.•A novel chemical kinetics model with tar cracking analyses gasification performance.