Effects of different operating parameters on the syngas composition in a two-stage gasification process

This research used a two-stage fluidized-bed gasifier to investigate the effects of the temperature, equivalence ratio, and steam/biomass ratio on the syngas composition. When the operating temperature in the first stage increased from 700 degrees C to 900 degrees C, the proportion of H-2 in the syngas increased significantly. After passing through the second stage (900 degrees C), the syngas produced from the first stage underwent the thermal reaction again, and the proportion of H-2 was further increased. When the ER value increased from 0.2 to 0.3, the proportion of H-2 in the syngas increased; whereas, when the ER value increased to 0.4, the amount of H-2 produced was reduced. For S/B ratio, an increase to 0.5 enhanced the steam content of the gasifier and accelerated the methane steam reforming reaction, thus producing more H-2 (up to 52 mol%). Furthermore, when the operating temperature of the fluidized bed reactor at the second stage was set at 900 degrees C, the proportion of H-2 in the syngas could still be effectively improved to more than 42 mol% although the operating temperature at the first stage was only 700 degrees C. The proportion of H-2 was enhanced to more than 52 mol% with a combination of appropriate ER and S/B ratio values. (C) 2017 Elsevier Ltd. All rights reserved.