Simulação de uma absorvedora com recheio na recuperação da propanona do ar

Abstract

The process of separating certain components is one of the most important operations in the chemical industry. Absorption columns are used in various unit operations to separate compounds to specify and market them, thus playing a fundamental role in the purification and concentration of chemical substances. The problem related to this equipment is associated with erroneous handling and unfamiliarity with computer modeling, especially from an industrial point of view, which leads to high operating, energy, and raw material costs, as well as affecting product quality, emitting pollutants into the atmosphere, and compromising the plant's operational safety. Therefore, this study focuses on a gas absorption column 1 m high and 0.07 m in diameter, with a glass Raschig ring filling, where water was used as a solvent to remove the volatile organic compound (acetone or propanone) present in the air. That said, to achieve more economical and efficient separations, this work aimed to simulate this column in particular, using the Aspen Plus® software as a tool, evaluating not only the influence of operational variables on transport phenomena but also on hydrodynamic behavior. The simulation was validated with experimental data obtained in the laboratory by Barbosa and Góis (2024), for the pressure drop, the fraction of acetone absorbed, and the volumetric mass transfer coefficient (KL.a). In conclusion, from the simulated results obtained by the hydrodynamic study together with the mass transfer, it was possible to validate the empirical data already collected in the column, regarding the pressure drop, for the air-acetone-water system with Raschig rings, using the Sherwood-Leva-Eckert (SLE) modeling, which showed an average deviation of 20%. In addition, the volumetric mass transfer coefficient (KL.a) was validated for a gas flow rate of 0.85 g/min, based on Bravo-Fair rate based modeling. For the other phenomena, the Bravo-Fair rate-based model proved to be the most suitable for the study, showing that an increase in gas flow is associated with a greater pressure drop, an increase in the probability of flooding, an increase in the fraction of acetone absorbed, in the interfacial mass transfer area and a better fit of the model about the experimental KL.a. Thus, the study provided reliability in analyzing the phenomena, as well as proposing improvements and substantiating topics that have not yet been studied experimentally in the column, thus facilitating future studies.