Comparison of the exergetic performance and CO2 emissions of tetrahydrofuran-water separation processes

There are different purification technologies aimed at separating azeotropic mixtures, among which extractive and pressure-swing distillation stand out. While the former is characterized by the use of a solvent, the latter is employed when the composition of mixtures is significantly affected by the operating pressure. In this article, said separation technologies are applied to a tetrahydrofuran-water mixture and further compared to one another in terms of their exergetic performance and CO2 emission rate. Two configurations were used as case studies and further improved in order to propose new fully-integrated designs. The exergy analysis was performed by determining both the total exergy destruction rate and exergetic efficiency, whereas the CO2 emissions were evaluated by estimating the indirect releases due to electricity and thermal energy consumption. Although the results showed that the proposed schemes have a higher exergetic performance and lower CO2 emission rate than their original designs, the extractive processes proved to be better than both pressure-swing technologies. More specifically, the proposed fully heat-integrated extractive configuration was deemed to be the best alternative since it has approximately 7.4 % lower exergy destruction rate and 7.2 % lower carbon emission rate than the fully heat-integrated pressure-swing scheme.