Syngas production strategies from biomass gasification: Numerical studies for operational conditions and quality indexes

Gasification is an enhanced thermal technique, as it affords a versatile synthetic gas (syngas) from which it is possible to obtain various commodity assets such as electricity, fuels and chemicals while conveniently disposing of biomass or waste residues.To the best of the authors’ knowledge, there are no publications thoroughly relating syngas quality features with its possible applications. The report of quality indexes for syngas is quite scarce once they depend on quality indicators which are difficult to reconcile and simultaneously adjust to meet the expected syngas characteristics. Therefore, in an attempt to fill this gap, this work reports the gasification modelling for miscanthus (M), peach stone (PS) and a mixture of polyethylene terephthalate and vine pruning (PET-VP) in order to determine syngas quality indicators and potential applications. The operational conditions were optimized through a parametric study for the achievement of high-quality syngas, varying temperature (T), equivalence ratio (ER) and steam to biomass ratio (SBR) and assessing the lower heating value (LHV), cold gas efficiency (CGE) and tar content.The main trends for the assessed parameters show improved calorific content for higher temperatures (800 °C – 850 °C), lower ER (0.2–0.25) and moderate SBR values (around 2.0). PET-VP displayed the higher LHV (around 9 MJ/Nm³) except when SBR was varied. In this case, M afforded enhanced calorific content (6.5 MJ/Nm³) which rapidly decreased for higher ratios. Conversion efficiencies of 70–80% were seen for the studied feedstocks and tar content was seen to decrease for higher temperatures, higher ER and higher SBR. PET-VP enabled the manufacture of chemicals and fuel gas, while M and PS originated syngas capable of producing synthetic fuels.