Optimal Design of Heat Integrated Reduced Vapor Transfer Dividing Wall Columns

Abstract

Abstract A dividing wall column (DWC) is capable of saving capital costs and improving energy efficiency for ternary liquid separations. Alternative DWC structures have been proposed, termed Reduced Vapor Transfer DWC (RVT-DWC) in this work, which involves less difficult-to-control vapor transfer streams. The most interesting RVT-DWC structure, the LL structure, which has a dividing wall extending throughout the column and has no interconnected vapor transfer streams, is studied in this work. Three heat integrated designs of the LL structure, the LL structure with combined condenser and reboiler (LL-CCR), vapor recompression assisted LL structure (VR-LL), and vapor recompression assisted LL structure with combined condenser and reboiler (VR-LL-CCR), are introduced and compared to the standard DWC, standard LL structure, and vapor recompression assisted DWC (VR-DWC) designs, respectively. Although the LL-CCR structure shows only minor improvement in total annualized costs (TAC) when compared to the LL structure, its vapor recompression assisted design (VR-LL-CCR) has the lowest TAC among all the structures studied (17 % lower than LL-CCR, 4 % lower than VR-DWC, and 10 % lower than VR-LL). Moreover, the vapor recompression assisted structures have lower TAC than their corresponding base structures.