Abstract:
Distillation is the most widely used fluid separation and purification process, and accounts for a major share of the total energy consumption of the process industry. However, because of its relatively low thermodynamic efficiency, it is a prime target for process intensification studies. Numerous alternative designs have been explored with the aim to reduce thermodynamic losses in distillation columns and to improve the overall process efficiency. Among non-conventional distillation technologies, heat-integrated distillation processes have received particular attention due to potentially substantial energy savings.
The objective of this research project is to study exergy losses in various heat-integrated distillation columns. A conventional industrial-scale i-butane/n-butane fractionator has been selected as a case study for comparison of the performances of various heat-integrated designs. Aspen Plus® process simulator is used to perform steady-state simulations and exergy analyses of the conventional distillation column (CDC), internally heat-integrated distillation column (iHIDiC), externally heat-integrated double distillation columns (EHIDDiC), and vapor recompression (VRC) system. The results of these exergy analyses show that a modified VRC system ()E10.69%η= is the most efficient design for this separation. Exergy efficiency of the conventional VRC system is same as that of the CDC ()E9.27%η=. EHIDDiC system ()E9.77%η= is somewhat better than the CDC, whereas iHIDiC shows poor exergy efficiency ()E8.09%η=, even lower than the CDC.
