Evaluation of the energy generation potential by an experimental characterization of residual biomass blends from Córdoba, Colombia in a downdraft gasifier

An experimental characterization of crop residue biomass blends to evaluate their energy potential was conducted using an experimental approach in a commercial scale downdraft gasifier. Corncobs, rice husks, sesame stalks and cotton gin refuse were used to study the effect of mixture proportions on equivalence ratio, gasification temperature, syngas lower heating value (LHV), and cold gas efficiency (CGE). Using an experimental mixture design, thirty-two sample blends were evaluated in an Ankur WBG-30 downdraft gasifier with 30 kg/h feed supply coupled with a syngas purification system, temperature sensors and a gas chromatograph. Syngas composition CO, H₂, CH₄, N₂ and CO₂ are presented for each blend. It was found that temperature, syngas composition, syngas lower heating value and cold gas efficiency were negatively affected as the proportion of rice husks in the mixture was increased. It was possible to reach CGE values up to 57.91% and LHV up to 4460 kJ/kg under certain blending conditions. A higher percentages of rice husks caused a considerable increase in the variability of the equivalence ratio resulting in suboptimal gasification conditions.