Enhancing ammonia reactor efficiency: Numerical modeling and optimization with internal cooling exchanger

Abstract

This study presents a comprehensive modeling and optimization framework for enhancing the performance of an industrial-scale ammonia synthesis reactor through the integration of internal intermediate cooling exchangers (IICE), which has not been previously modeled or optimized in a real industrial context. Focusing on the Shiraz Petrochemical Complex, both one-dimensional (radial) and two-dimensional (radial–axial) reactor models were developed using MATLAB and COMSOL, respectively, to solve the mass, energy, and momentum conservation equations under realistic operating conditions. Model validation against plant data demonstrated excellent agreement, confirming the accuracy of the proposed models. To improve reactor performance, a Differential Evolution (DE) algorithm was applied to optimize key operating parameters namely reactor inlet temperature, pressure, and feed flow rate. The optimized conditions (463.9 K, 169.99 bar, and 292,476 kg/h kg/h) led to a 16.2 % increase in ammonia molar fraction compared to current operation, achieving a maximum value of 0.21. The novelty of this work lies in the systematic integration and assessment of IICEs in a multi-bed configuration, previously unvalidated in literature. It also evaluates potential economic impacts, demonstrating that coupling internal heat recovery with numerical optimization can enhance ammonia synthesis and lower energy consumption in industrial reactors.