Design and control of economically attractive side-stream extractive distillation process

Abstract

The performance and effectiveness of the conventional and heat-integrated side-stream extractive distillation arrangements are explored with the simultaneous consideration of the steady-state economics, thermodynamics and dynamic controllability aspects of the process. The overall performance of simple stream-to-stream heat-integrated F-S-E configuration (serially preheating column inlet feeds by solvent stream) is superior to others because of the least total annual cost (TAC), CO2 emissions and highest second-law efficiency among these side-stream cases. It can further reduce 8.16% in TAC compared to the conventional extractive distillation configuration. Exergy and entropy generation analyses are employed in these heat-integrated side-stream extractive distillation arrangements to thorough evaluate the energy degeneration in each component. Furthermore, dynamic control analyses for conventional and heat-integrated side-stream extractive distillation processes are also explored. Two novel compromised tactics are proposed to make the economically optimal heat-integrated arrangement more stable at rejecting large feed disturbances according to the physical implemented issues of economizers. Both effective and robust dual-product quality controls are provided for tackling the large (20%) throughput and feed composition perturbations. Furthermore, a new developed control scheme with parallel arrangement works better than that with series exchangers’ arrangement by comprehensively weighing results of steady-state economic design and dynamic controllability.