Concentration of HCl, HF and sulfur compounds in fuel gas from fluidized bed gasification of coals and wood by steam-oxygen mixtures

The presence of HCl, HF, tar, and sulfur compounds in fuel gas from the fluidized bed (FB) gasification of coals and wood was studied. The combined effects of coal char with special ash composition (higher Ca and Fe content) had beneficial effect on HCl, HF, and on S-compounds emissions (particularly thiophene). The less reactive bituminous coals (South African (SA)-coal) with high content of SiO₃ and Al₂O₃ in ash could exert elevation of HCl emission during time of gasification with accumulation of coal char in bed. However, the S-compounds concentrations in producer gas always decreased during time of FB gasification. The presence of calcined dolomite together with sand in FB gasification had prevailing positive effect on emission reduction of HCl, HF, sulfur compounds, and tar for reactive coals (German coal). Even emissions of organic sulfur compounds (thiophene and benzothiophene) were reduced. Heavier tar compounds concentrations in fuel gas from FB gasification of reactive subbituminous coal (German coal) were lower than corresponding tar compounds concentrations in FB gasification of wood or less reactive bituminous (SA) coal. Accumulation of coal-char in FB significantly reduced tar compounds concentration in producer gas from reactive coal gasification. Emissions in FB gasification of wood on sand particles could be reduced by the presence of calcined dolomite particles (dust). This is an abstract of a paper presented at the CHISA 2012 - 20th International Congress of Chemical and Process Engineering and PRES 2012 - 15th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (Prague, Czech Republic 8/25-29/2012).