城市污泥热解–气化中气氛调控的关键作用

Pyrolysis-gasification process is a promising technology for the sustainable management of municipal sewage sludge. However, the elemental composition and structural properties of sludge biochar, which are significantly influenced by the pyrolysis atmosphere, play a crucial role in the subsequent gasification process. This study aims to uncover the impact of pyrolysis atmosphere on the reactivity of biochar gasification by evaluating the sludge biochar obtained under different pyrolysis atmospheres. The results revealed that a CO₂-enriched atmosphere notably increase the C content of the pyrolysis biochar. The C/H and C/O ratios of biochar under a 30%N₂ + 70%CO₂ are 1.27 and 1.88 times higher than those under 100% N₂, respectively. The CO₂ atmosphere promoted deoxygenation and aromatization, enhancing the graphitic structure of biochar. In gasification, biochar from a 100% CO₂, at low heating rates (10 and 20 ^◦C/min), shows 1.14 and 1.15 times higher overall and local gasification indices compared to that from 100% N₂. This research highlights the importance of the interplay between biochar preparation and gasification heating rates, which is key to optimizing gasification reaction parameters for efficient sludge management.