Process design and simulation of methyl isobutyl ketone (MIBK) dehydration by batch distillation: A study on unit configuration and operational policies

Resumen

Heteroazeotropic batch distillation of methyl isobutyl ketone-water binary mixture is investigated, seeking a reliable operation for dehydration of methyl isobutyl ketone (MIBK). The dynamic batch distillation module (BatchSep) of the commercial package Aspen Plus V.12.1 (R) is applied for simulations. An initially fed unit at atmospheric pressure is simulated from the heating-up step until it reaches the desired MIBK purity of 99.8 wt%. Three configurations, namely conventional batch distillation unit (Mode I), batch distillation unit with decanter (Mode II), and a simple distillation unit (Mode III), are compared in a wide range of operating conditions. The effects of condenser temperature and the number of theoretical stages are also examined. According to the results, applying a decanter (Mode II) with a return fraction of over 0.75 for the MIBK-rich phase and below 0.4 for the aqueous phase provides higher MIBK recovery than the maximum achievable value in a conventional unit (Mode I), with almost no increase in process time. A perfect decanter offers an almost complete MIBK recovery, which is about 5% over the maximum value by conventional units (Mode I). Moreover, cutting the reflux (Mode III) offers the fastest way to the desired product but provides the lowest MIBK recovery value. The aqueous phase return fraction does not significantly impact MIBK recovery, but if it exceeds 0.5, it remarkably affects the process time/energy cost. When maximum MIBK recovery rate/minimum energy cost is desired, applying a decanter (Mode II) with a return fraction above 0.5 for the MIBK-rich phase and below 0.55 for the aqueous phase yields a higher production rate and a lower energy cost per unit quantity of product compared to the best achievable values for a conventional unit (Mode I). A perfect decanter improves production rate and energy efficiency by 8 % over the best case in a conventional unit (Mode I). Also, operation without reflux (Mode III) is preferred over a conventional operation (Mode I) with a total return fraction over 0.7 due to its superior energy efficiency and production rate.