Estudo de caso da integração energética em uma planta industrial de hidrodealquilação (HDA) do tolueno

Abstract

Hydrodealkylation (HDA) of toluene is the process in which toluene is taken to benzene through thermal and catalytic routes, but due the high energy cost used, several studies have been conducted to optimize the conversion of reactor reaction and energy recovery in the plant. Part of recent studies has as main idea the integration of unit operations aiming to reduce the number of equipment, the material and energy reuse of industries transforming the structure of chemical plants, making more compact, safe, more energy efficient, making the process more sustainable. One of the methods to make such analysis is the Pinch methodology that comprises in an analysis performed in plants involving thermal exchange processes in order to obtain better processing with greater energy efficiency. The HDA plant simulation was performed using the UniSim® Design software, where 92% pure benzene production was obtained, totaling 103.73 kgmol/h, which was quite satisfactory compared to the result of the literature simulation 135 kgmol/h. The energy integration proved to be quite effective, with the PINCH temperatures found being 335.8 K and 325.8 K for hot and cold currents respectively, the value of the amount of hot utility found was 30,723.3321 kW, while for the cold utility the value is 297.2625 kW, values found with a ΔTmin = 10 K. The integration by the HINT software was satisfactory, since it corroborated with the values previously calculated by the PINCH method, being the quantities of hot utilities and cold 30,716.15 kW and 330.38 kW respectively. The minimum number of heat exchangers for integration was 10 exchangers, both in the PINCH method and in the HINT software. The values obtained for the Total Annual Cost with the non-integrated and integrated economic analysis of the situations were R$ 51,761,843.07 and R$ 33,442,242.35 respectively, showing a savings of 35.40% in the costs with the integration energy. Thus, with the economic analysis, it is possible to ratify the importance of the study of energy integration, both in the financial and environmental spheres, because in addition to reducing costs it also decreases the demand for utilities and the emission of possible pollutants in the environment.