The present study is focused on the hydrogen production from natural gas (NG) as input in the large-scale industrial petrochemical unit located in Ilam province, west of Iran. The influence of flow rate, temperature, time, and pressure on the hydrogen production is discussed. This case study is based on accurate operating data from the actual plant in operation. In producing hydrogen, primary method SMR (Steam Methane Reforming) is used with different types of catalysts (CoMo, Zinc oxide, and Nickel-oxide). The optimum hydrogen is produced with 75.61% purity at the end of the system's cycle, and several factors are simultaneously responsible. However, temperature and flow rate have a considerable effect, but the necessity of pressure and the presence of other components are apparent. Additionally, exergy analysis results for the system indicate that the significant exergy destruction is related to the burner by 644.26 MW, and minimum exergy destruction belongs to Heater 1, which worked as a condenser, with 4.42 MW. Furthermore, the highest exergy efficiency was obtained for Drum with 66.53%, and the lowest exergy efficiency belongs to Desulphurization Reactor with 1.5%. The exergy efficiencies of gas products were calculated as well as hydrogen, methane, and nitrogen as the highest, middle, and the lowest achieved 68.06, 16.54, and 0.00064%, respectively. In the final part, the overall exergy efficiency of the system was calculated as 20.93%. Considering the components which the most exergy destruction occurred and controlling the input parameters such as pressure, flow rate, temperature, and catalysts leads to the exergy efficiency and hydrogen production improvement substantially.
