The aim of this project is to optimize energy consumption in a gas sweetening unit. For this purpose, the Aspen HYSYS and HTRI software were used to simulate the process and analyze the performance of shell and tube heat exchangers. Initially, the process was simulated and compared with the design data (PFD) for validation and verification to ensure the accuracy of the results. In the next stage, the simulation was conducted using the unit’s real operational data for two amine flow rates of 260 and 360 cubic meters per hour. The objective of these simulations was to perform sensitivity analysis of the process and assess the impact of various changes on process performance. In this section, the effects of fouling and tube plugging up to 25% were simulated both individually and in combination. The results indicated that fouling has the most significant impact on reducing heat exchanger efficiency and increasing energy consumption, while tube plugging alone does not considerably affect efficiency. Subsequently, a plate heat exchanger was designed as an alternative to the shell and tube heat exchanger. This plate heat exchanger was designed to operate under the process flow conditions to achieve higher efficiency and reduce energy consumption. In the economic analyses, based on the prices provided by the client on October 4, 2024, a comparison was made between the performance of the shell and tube heat exchanger in clean and fouled conditions, as well as the replacement of the shell and tube heat exchanger with a plate heat exchanger. This comparison was carried out for two amine loading conditions: one with a capacity of 260 cubic meters per hour (Condition A) and the other with 360 cubic meters per hour (Condition B). The results showed that the energy cost difference between the clean and fouled conditions for Condition A was approximately €776,000 per year, of which €493,000 was attributed to low-pressure steam costs (accounting for 63.6% of the total cost differenc