Release Behavior of Sulfur during Fluidized Bed Gasification

During fluidized bed gasification, sulfur in coal will be released, which will lead to environmental pollution. The release behavior of sulfur in fluidized bed gasification has not been fully studied, although fluidized bed gasification technology has a promising prospect. Thus the release behaviors of sulfur during fluidized bed gasification were investigated comprehensively through two aspects: temperature and reaction atmosphere. During air gasification, the main gaseous sulfur is H2S, followed by COS, and the yield of SO2 and CS2 is low. With the increase of temperature, both of the released sulfur and the percentage of inorganic sulfur in gas phase increase. Under the same working condition, the distributions of sulfur forms in gasification residues are analogous. Organic sulfur is the dominate sulfur forms in the gasification residues. Sulfate in residues increases while organic sulfur decreases with increasing temperature. Among three reaction atmospheres (CO2/steam/air) studied, the yield of H2S is the most among the above four kinds of gaseous sulfur. The percentage of H2S in gaseous sulfur (H2S/Sg) is the highest in the process of steam gasification, while most sulfur is released during air gasification. The sequencing of H2/CO is the same as that of H2S/Sg, while the trend of sulfur release rate is consistent with that of carbon conversion rate. The distributions of sulfur species in the fly ash of CO2 gasification and steam gasification are similar, while the sulfate content in the fly ash of air gasification is the highest.