(537b) 3E (Energy, Economic and Environmental) Analysis for Natural Gas Based Blue Ammonia Synthesis Process through Multi-Objective Optimization

Ammonia production as a hydrogen carrier is in the spotlight. However, the ammonia synthesis process accounts for 1.0% of global CO2 emissions. Therefore, in this paper, the blue NH3 synthesis process was simulated by adding Carbon Capture and Storage (CCS) to the natural gas-based ammonia synthesis process. After designing the ammonia synthesis process, heat integration was performed to show the Grand Composite Curve (GCC). Four case studies were conducted for the Haber Bosch reactor type. Case A: Adiabatic Quneching Cooling Reactor (AQCR), Case B: Adiabatic Indirect Cooling Reactor (AICR), Case C: AQCR w/ purifier, Case D: AICR w/ purifier. Case D, which consumes the least energy, was selected as the base case of Haber Bosch in this paper. Then, for the process, sensitivity analysis was performed on temperature, pressure, and yield in Haber Bosch section. The ammonia synthesis process was analyzed for three purposes: 1) Energy analysis (Energy consumption for NH3 synthesis, GJ/tNH3), 2) Economic analysis (Levelized Cost Of Ammonia, $/tNH3), 3) Environmental analysis (Global Warming Potential, tCO2eq/tNH3). As a result of 3E (Energy, Economic, Environmental) analysis of the ammonia synthesis process, variables showing a trade-off relationship between Economic and Environmental were selected and MOO (multi-objective optimization) was performed using genetic algorithm. Then, among MOO results, 3E results were analyzed by dividing them into three scenarios based on economic feasibility and environmental characteristics. As a result of the analysis, the LCOA of the scenario with the best economic feasibility is 320.79$/tNH3, and the GWP is 0.5000tCO2eq/tNH3. The LCOA of the scenario with the best environmental performance is 343.97$/tNH3, and the GWP is 0.4541. As such, when designing Blue NH3, it is possible to obtain an optimized result while considering economical and environmental characteristics at the same time.