Ammonia is one of the most essential petrochemical products, and about 80% of its global production is utilized in fertilizer industries. Modification of ammonia synthesis reactors can impact the economics of ammonia plants. This research aims to develop and design new configurations for an industrial ammonia synthesis reactor. For this purpose, we developed a steady-state one-dimensional pseudo-homogeneous model for a horizontal Kellogg reactor. The reactor consists of four catalytic beds equipped with an inter-stage cooling system. Rung-Kutta’s 4^th-order method was used to solve ordinary differential equations (ODEs). The validity of the proposed model was verified by comparing the simulation results to existing industrial Kellogg reactor data. Two new configurations based on a modification of the Kellogg reactor were designed and simulated. The simulation results show that the percentages of production increase for the first and the second configurations are 2.29% (2902 Nm³/hr) and 4.52% (5278 Nm³/hr), respectively. Also, the operating temperatures of the newly designed reactors are 15-17 ℃ lower than the conventional Kellogg reactor. This advantage helps improve the stability and catalyst lifetime alongside the beds. Moreover, a high-pressure (HP) steam generator in the suggested configurations produces HP steam that can reduce the plant’s energy consumption.