Pressurized gasification of lignite in a pilot scale bubbling fluidized bed reactor with air, oxygen, steam and CO2 agents

In this study, 80 h continuously operated gasification experiment was carried out with pilot scale pressurized bubbling fluidized bed gasifier which was operated with the coal feed capacity of 500-520 kWth (80-83 kg/h coal feed rate). The mixture of air, steam, oxygen and CO2 was used as gasification agent with different ratios. The operating pressure of gasifier in this experiment was between 2.4 and 2.7 barg. The effects of ER, steam/carbon ratios and CO2/carbon ratios on syngas composition, carbon conversion ratios and cold gas efficiencies were investigated. According to the results, using CO2 or H2O as gasification agent, may have both advantages and disadvantages for the operation. If CO2 was increased in gasification agent, shift reaction was effected negatively and H2 products were decreased. If steam was increased, cold gas efficiency was slightly decreased.