Energy-Efficient Design of an Ethyl Levulinate Reactive Distillation Process via a Thermally Coupled Distillation with External Heat Integration Arrangement

In this paper we describe an energy-efficient process design using a reactive distillation (RD) of the esterification reaction for the synthesis of ethyl levulinate I (LAEE). Two designs, a neat design and an excess design, were examined to find the best configuration for the process. In the neat design, there are two columns with equal molar feeds to produce LAEE. An additional column is required in the excess design to separate LAEE from the unreacted reactant (levulinic acid, LA). Later in the process, this unreacted LA is recycled back into the RD column. Compared to the neat design, the excess design showed superiority for the esterification process in terms of the total annual cost (TAC) and energy requirement. Therefore, three energy integration configurations, external heat integration (HI), thermally coupled distillation (TCD), and a combination of TCD and HI, were investigated in this excess design. A side reboiler was implemented in the water removal column to overcome the limitation of the temperature difference for heat transfer. The simulation results showed that the configuration of TCD with HI was the best one, which saved 32.9% and 10.5% of the energy and TAC, respectively, compared to the conventional RD with three columns without HI.