Effect of Operational and Structural Parameters in Dividing Wall Column Distillation Energy Efficiency for Separation of Methanol, Isopropanol, and N-Butanol

Although distillation is considered a mature process, it is associated with high energy consumption. Distillation is reported to consume 40 percent of the energy used in the chemical industries worldwide. In this paper, the steady-state simulation of two processes, including two conventional distillation columns and DWCD, is conducted. The influence of operational and structural parameters in the DWCD energy efficiency for separation methanol, isopropanol, and n-butanol is performed. In the conventional method, there are two distillation columns with two reboilers and two condensers, while in DWCD, there are one reboiler and one condenser. A model consisting of four columns including two absorbers, a rectifier, a stripper, and two vapor and liquid splitters are used to simulate the DWCD. The number of stages in the absorbers columns is indicating the wall height in DWCD. The various parameters have been optimized using sensitivity analysis to minimize heat duties of the reboilers and condensers with considering the limitations for the concentrations of methanol, isopropanol, and n-butanol in the products. The studied parameters can be divided into two categories of structural and process parameters. The structural parameters include the number of stages in each column, the feed stage number, and the side product stage number. The process parameters include the reflux ratio, the vapor split ratio, and the liquid split ratio. According to the results, the DWCD, in compared with the conventional distillation columns, saves energy 19.95% for the reboiler heat duty and 20.64% for the condenser heat duty for the investigated process.