Thermodynamic analysis and reaction kinetics of a flue gas recirculation-enhanced pyrolysis-gasification cycle for low-heating-value syngas combustion

A novel low-heating-value syngas combustion-biomass pyrolysis and gasification cycle system is introduced in this study, marking a significant advancement in renewable energy conversion. Unlike conventional approaches, the integrated system utilizes Phragmites communis, an aquatic plant as feedstock, and employs a unique coupling of Aspen Plus thermodynamic modeling with reaction kinetics. This integration enables a comprehensive simulation of the entire process, from pyrolysis and gasification to syngas combustion. By optimizing flue gas recirculation, the system’s closed-loop design significantly boosts energy efficiency and substantially reduces pollutant emissions.At a flue gas reflux ratio of 0.2, the system achieves a remarkable thermal efficiency of 69.22%, while maintaining stable combustion even at practical operating conditions with a slightly lower reflux ratio of 0.3, yielding a thermal efficiency of 61.27% and minimal CO and NO_X emissions. This research stands out by addressing the limitations of traditional biomass gasification, such as tar formation and low heating value gas combustion instability, through the synergistic integration of flue gas waste heat recovery and internal gasification agents. The proposed system offers a green and low-carbon solution for biomass conversion, providing a robust framework for optimizing energy structures and reducing greenhouse gas emissions.