Morphology-controlled biomass pyrolysis for enhanced tar and syngas yields: A lattice Boltzmann approach

Biomass pyrolysis serves as an effective approach to convert low-grade biomass into high-value energy carriers (tar and syngas), with particle morphology characteristics significantly influencing the thermochemical conversion process. This study employed the Lattice Boltzmann Method (LBM) to solve conservation equations coupled with a pyrolysis kinetic model incorporating three parallel primary pyrolysis and a set of secondary pyrolysis. The investigation comprised three systematic approaches: (1) analysis of elliptical cross-section cylindrical particles with fixed horizontal axis dimensions but varying particle aspect ratios(λ), followed by (2) comprehensive evaluation of pyrolysis yield of varying sizes with identical aspect ratios, (3) analyze the effects of aspect ratio variations under constant cross-sectional area. Key findings revealed that particles with λ = 0.250 exhibited maximized tar and syngas yields, while char production peaked at 20.84% for spherical particles (λ = 1.000) when the dimension of the horizontal axis remains unchanged. Particle size analysis demonstrated an inverse correlation between dimension scale and volatile production. Rreciprocal aspect ratio pairs (λ and 1/λ) exhibited thermal response asymmetry, where lower λ values accelerated pyrolysis process. The spherical configuration displayed prolonged conversion duration and minimized volatile release due to radial heat transfer limitations. When maintaining a constant cross-sectional area, altering the aspect ratio not only has a effect on tar and syngas yield but effectively reduces the conversion time. These findings demonstrate the critical role of particle morphology engineering in biomass pyrolysis optimization, proposing strategic control of aspect ratio and particle dimensions for targeted product distribution.