Characteristic simulation and full dimensional performance analysis of ammonia production system by chemical chain gasification coupled with water gas shift

This study utilized Aspen Plus software to design a novel biomass chemical looping gasification ammonia production system. The system consists of subsystems such as chemical looping gasification, water-gas shift, and ammonia synthesis, utilizing hydrogen generated from the chemical looping gasification and water-gas shift processes along with nitrogen from the air reactor to synthesize ammonia, while simultaneously enriching and storing CO2 in the process flow. This paper investigated the effects of process parameters such as reaction temperature, H2O/C, and Fe2O3/C on the ammonia production process and employed a random forest model for parameter optimization prediction. The study found that near-optimal operating parameters could be achieved under moderate temperature, high steam flow rate, and low oxygen carrier flow rate conditions. Specifically, the optimal NH3 yield of 39.20 % was obtained at a gasification temperature of 724.14 °C, H2O/C of 2.03, and Fe2O3/C of 0.10, with the system's exergy efficiency at 34.50 % and energy efficiency at 40.37 %. Based on this, exergy analysis, energy analysis, environmental analysis, and economic analysis were conducted on the system. The global warming potential values for the Air Reaction, Fuel Reaction, WGS, and NH3 synthesis systems were found to be 0.25 kg CO2-eq/kg NH3, 1.34 kg CO2-eq/kg NH3, 0.04 kg CO2-eq/kg NH3, and 1.57 kg CO2-eq/kg NH3, respectively. The system's utility costs were the highest, accounting for 33.07 %. The system could begin recovering its initial investment costs after 7 years, with a net present value reaching 3.89M$ over a 20-year lifecycle.