Highly integrated system for ammonia and electricity production from biomass employing direct chemical looping: Exergy and exergoeconomic analyses

An integrated system was developed to simultaneously produce ammonia and power using biomass as feedstock. The proposed system has the following subsystems: (i) self-heat recuperation-based drying to significantly reduce energy consumption, (ii) direct chemical looping hydrogen production with two-stage combustion to obtain highly purified hydrogen and nitrogen, (iii) Haber-Bosch (H-B) process to produce ammonia, and (iv) BraytonRankine combined cycle to exploit the thermal energy of purged gas from the H-B process. In-depth exergy and exergoeconomic analyses were performed. Self-heat recuperation-based drying achieved an energy-saving ratio of up to 93.4% compared to traditional drying. Exergy analysis showed that the exergetic efficiencies of ammonia and net power production were 44.36% and 1.73%, respectively. The largest exergy destruction occurred in the fuel reactor, accounting for approximately 28% of the total exergy destruction. Exergoeconomic analysis revealed that refrigerator and some pressure-changing components (MComp1, Comp, MComp2, and EXP1) have higher cost reduction potential; a decrease in cost rates (ZK s) (as well as purchasing costs) of these components is necessary for system cost reduction. The final product cost allocation demonstrated that the unit costs of ammonia and electricity were 29 USD/GJ and 140 USD/GJ, respectively, under the initial input parameters.

Automated summary

An integrated system was developed to produce ammonia and power simultaneously using biomass as feedstock. By utilizing self-heat recuperation-based drying, the system achieved a high energy-saving ratio of up to 93.4% compared to traditional drying methods. Exergy and exergoeconomic analyses revealed the energy efficiency and cost reduction potential of the system, emphasizing the importance of reducing costs for specific components like refrigerators and pressure-changing components. The unit costs of ammonia and electricity were determined to be 29 USD/GJ and 140 USD/GJ, respectively, under the initial input parameters.