Design and analysis of an ethyl benzene production process using conventional distillation columns and dividing-wall column for multiple objectives

Downstream separation in the ethyl benzene (EB) production is energy intensive due to the use of multiple distillation columns. One technology to achieve significant energy and capital cost savings for this separation, is the use of dividing-wall column (DWC) to replace conventional columns. In the present study, a typical industrial EB process including reaction, separation and heat exchangers, is first simulated rigorously and modified to improve the efficiency and performance of both individual units and the overall plant. DWC is integrated into the EB process, and its performance is compared with the base case of utilizing only conventional columns for downstream separation. All simulations are performed using Aspen HYSYS, and design data used is appropriately validated for realistic simulation. Subsequently, sensitivity analysis is performed on both EB designs for a number of design variables. Objectives selected for sensitivity analysis are net present value, total capital investment and benzene loss. Results show that integrating DWC is not only viable but also offers potential to reduce capital investment, decrease benzene loss and increase profit compared to a conventional column design for the EB process.