Retrofitting an isopropanol process based on reactive distillation and propylene-propane separation

•Reactive distillation (RD) based Isopropanol (IPA) process is designed.•RD-based IPA process is analyzed to identify its limitations & contributing units.•Two retrofit designs for the RD-based IPA process are developed and analyzed.•One retrofit design with two RDs reduces cost of manufacture by 14.1%.

In this study, an isopropanol (IPA) process based on reactive distillation (RD) using excess propylene and propylene-propane separation column (splitter) is analyzed for retrofitting. This analysis led to identifying two limitations of this process, namely, excess propylene feed to RD and requirement of high purity IPA product from RD. To overcome these limitations, two retrofit designs are proposed. One modified process introduces a new RD with excess water to replace the propylene-propane splitter; simulation results show 14.1% reduction in manufacturing cost per unit product (MCU, decreases from 0.092 $/kg to 0.079 $/kg) for this retrofit design. In the other retrofit design, RD produces an azeotropic mixture of IPA and water, thus requiring extractive distillation and solvent recovery columns. This modified process leads to a slight increase in MCU (from 0.092 $/kg to 0.095 $/kg). Hence, the design involving a new RD with excess water is recommended for retrofitting the original process.

Graphical abstractLinks between process limitations and the factors causing them.Figure optionsDownload full-size imageDownload as PowerPoint slide