Distribution of sulfur species in gaseous and condensed phase during downdraft gasification of corn straw

This study concerns the distribution of sulfur species during the gasification of non-woody biomass. Experiments were carried out in a downdraft fixed bed gasifier using air and steam as oxidizing agents. Based on RSM (response surface methodology), the study investigated three operating parameters, including the ER (equivalence ratio), steam to biomass mass ratio (S:B) and biomass particle size. The independent factors were tested in the range of 0.2-0.4, 0.8-1.2 and 2.5-8.5 mm for the equivalence ratio, steam to biomass mass ratio and biomass particle size. The response variables investigated were gaseous sulfides, including H2S (hydrogen sulfide), COS (carbonyl sulfide), CH3SH (methyl mercaptan) and SO2 (sulfur dioxide), as well as the condensed phase of sulfur that retained in the fly ash and the bottom ash. The results indicate that the three operating conditions significantly affect the distribution of sulfur compounds, and the equivalence ratio is found to be the most important factor.