Influence of coal ash on CO2 gasification reactivity of corn stalk char

The effect of added coal ash on the gasification behavior of corn stalk char by using the thermal-gravimetric analysis and a lab-scale horizontal fixed bed furnace was investigated. For comparison, synthetic ash with different chemical composition was used for studying the effect of difference ash composition on promoting/inhibiting the gasification reactivity. The results show that the slagging-control preferred coal ash additive has a negative impact on the gasification performance. Interestingly, a relatively less slagging-control preferred coal ash additive has a beneficial impact on promoting the gasification performance under low gasification temperature. This could be due to the difference composition between the two coal ash additives, where the former coal ash type has much lower content in the calcium and iron. In addition, the findings in the synthetic ash suggest that iron can have a better performance in promoting gasification than calcium/magnesium. Two types of coal ash show an inhibiting effect under higher temperature due to temperature might be the dominant factor and the restraining effect of additive. These observations are also supported by the evolution of char structure by using the Raman spectroscopy. Further, the modified random pore model can correlate well with the gasification kinetics data. (C) 2019 Elsevier Ltd. All rights reserved.