Sensitivity Analysis on Absorber Column as Hydrogen Gas Purification Unit Using Aspen Plus

 The absorption process involves transferring molecules from the gas phase to the liquid phase. In this study, an absorption column was utilised to separate acid gas from the byproduct of hydrogen gas using NaOH solvent. However, an issue related to fluctuating pH in the bottom product was encountered, which affected the quality of absorption in the column. One of the objectives of this study was to determine the effects of NaOH mass fraction in the solvent on the pH and the amount of acid gas absorbed in the column's bottom product. The process was simulated using ASPEN PLUS, and the sensitivity analysis indicated that changes in pressure and solvent mass flow rate directly affect absorption quality. In contrast, changes in solvent temperature have an inverse effect on absorption quality. Additionally, the mass fraction of NaOH in the solvent is directly proportionate to the absorption quality and pH value of the bottom product, showing high sensitivity to the pH value. When adjusting the NaOH fraction in the solvent within the range of 2–5%, the pH of the bottom product fluctuates from pH 0.9 to 12.2. The study illustrated the effects of variables on process operation parameters.