Optimal strategy for clean and efficient biomass combustion based on ash deposition tendency and kinetic analysis

摘要

Realizing low ash deposition tendency while simultaneously ensuring good combustion performance are dual objectives for clean and efficient biomass utilization. To reach this goal, this study proposes a strategy that involves blending corn straw (CS) with water-leached CS (H2O-CS) and HCl-leached CS (HCl-CS) for co-combustion. Deposition-predictive indexes and kinetic studies were adopted to evaluate the ash deposition tendency and combustion performance, respectively. Moreover, a potential synergy between the high-quality pores of leached CS and the catalytic effect of alkali and alkaline earth metals (AAEMs) presented in raw CS was proven and clarified. It was concluded that leaching could create a more porous structure, thus facilitating better contact and reaction of reactants during combustion. It could also reduce the ash deposition tendency. To be specific, raw CS had a high deposition risk, H2O-CS had a medium or low risk, while HCl-CS had a low risk. However, raw CS presented the highest combustion reactivity compared to H2O-CS and HCl-CS due to its high AAEMs content. Interestingly, the co combustion strategy proposed here showed that blending raw CS with leached CS could not only enhance the combustion performance but also reduce the ash deposition risk as a result of the synergy mentioned above. In addition, the optimal synergy between the loose structure (leached CS) and AAEMs (raw CS) can be obtained under certain conditions. It was the highest in the co-combustion of H2O-CS or HCl-CS with raw CS with at blending ratios of 50 wt% and 20 wt%, respectively. These findings could offer a strategy with dual functions (coupling the pore structure and AAEMs catalysis), and provide methods for the clean and efficient utilization of biomass. (C) 2020 Elsevier Ltd. All rights reserved.