Energy, exergy, economic and environmental analysis of a novel steam-driven vapor recompression and organic Rankine cycle intensified dividing wall column

Abstract

The dividing wall column (DWC) is a typical thermal coupled distillation column to separate the ternary mixture instead of the conventional two-column sequence. However, the energy utilization of DWC is the same as the conventional distillation column with large energy consumption. The current energy intensification measures for DWC is to use the vapor recompression (VRC) technology for retrofitting the stream cycle and use organic Rankine cycle (ORC) for waste heat recovery. The large top and bottom temperature difference of DWC limits the energy and economic benefit of VRC and also the production of ORC is not high. In this paper, unlike the general electric-driven VRC and waste heat recovery to save the energy consumption of the DWC (VRC-WHRS-DWC), a novel steam-driven VRC and waste heat recovery assisted DWC (SD-VRC-WHRS-DWC) is proposed to form a new energy utilization mode of DWC. As comparison, DWC and VRC-DWC are also developed. The single- and multi-objective genetic algorithms are used to optimize the different processes. All the processes are evaluated by energy, exergy, economic and environmental (4E) analysis. The result shows the cascade utilization of the steam in steam-driven system can effectively increase the economic benefit and decrease the energy consumption of DWC with the large temperature difference between top and bottom.