Shahriar Osfouri

The purpose of exergy analysis in processes is to assess and improve the efficiency of energy conversion systems by identifying and quantifying thermodynamic inefficiencies. By calculating exergy efficiency and exergy destruction rates, this analysis provides benchmarks for evaluating the performance of different system components and optimizing energy systems. This leads to designs that minimize energy losses and enhance operational efficiency. In this study, the exergy analysis of the Damavand Petrochemical air separation unit (oxygen production) was conducted. The air separation unit was simulated using HYSYS software. Exergy studies revealed that the highest exergy losses were associated with the distillation columns, accounting for 36% of the total process exergy destruction. After validating the simulation and studying the exergy performance of the unit, the feasibility of by-product production was investigated. Along with oxygen production, significant amounts of pure nitrogen are generated, making ammonia production a viable option in this study. The amount of ammonia produced was estimated at 2,337.6 tons per day, utilizing hydrogen obtained from a water electrolysis unit. Additionally, the feasibility of helium production from air was examined. Although the helium content in air is minimal (about 5 ppm), the large volume of processed air in the unit enables the production of approximately four 50-liter helium cylinders per day per unit. The selection of an optimal helium extraction method is crucial to ensure high purity while minimizing energy consumption and costs. In this study, three major processes for helium extraction were reviewed and compared: cryogenic processes, pressure swing adsorption (PSA), and membrane separation.