Modeling investigation on biomass gasification coupled with chemical looping oxygen uncoupling

In this study, the integrated dynamic model of biomass gasification and chemical looping oxygen uncoupling process was established. In view of the significant influence of carbon surface heterogeneous reaction kinetics on process performance, the RCstr module was used to simulate the gasification reaction, and the dynamics parameters were directly integrated into Aspen Plus by writing an external Fortran subroutine. This method overcame the limitation caused by the traditional RGibbs module only considering thermodynamic factors, realized the comprehensive coupling of dynamics and thermodynamic factors, significantly improved the accuracy and reliability of simulation results. The effects of steam biomass ratio (S/B), equivalent ratio (ER), pressure and temperature on syngas quality were further investigated. The results showed that the optimal reaction conditions included S/B = 0.036, ER = 0.3, P = 1 atm, T = 1000 K with a carbon conversion rate close to 100% and calorific value of 11772 kJ/Nm3, the cold gas efficiency reached 47.93%. Finally, energy analysis and exergy analysis were conducted, which revealed that low temperature along with appropriate ER and low S/B can effectively reduce overall energy consumption. Under optimal conditions, the energy consumption and exergy efficiency were 28.744 MJ and 52.33% respectively. Exergy loss was primarily caused by the irreversibility of pyrolysis and gasification processes.