Design and simulation of a new cascaded ammonia synthesis system driven by renewables

Abstract

This study proposes a new configuration for synthesizing clean ammonia using clean hydrogen produced by the renewables. The proposed system mainly consists of proton exchange membrane electrolyser, pressure swing adsorption unit, compressor, ammonia synthesis reactors and condenser. The designed configuration uses a cascaded approach for ammonia synthesis by employing two reactors in series to achieve high conversion ratios and to reduce the recycle loops. The proposed system is simulated using industrial software Aspen Plus V11 and Aspen adsorption V11 and the obtained results are discussed in detail. The designed system is investigated under different operating conditions. In the Aspen Plus simulation, both stoichiometric and Gibbs reactors are installed alternatively to investigate the ammonia synthesis process in depths and to establish the effect of temperature and pressure on the ammonia production capacities. The maximum exergy destruction rate of 65.43 kW is offered by the primary ammonia synthesis reactor. The energetic efficiency of the clean ammonia synthesis system is found to be 61.14% and exergetic efficiency is 65.5%. Furthermore, the outcomes and generated results are presented and discussed.