Multiple transesterifications in a reactive dividing wall column integrated with a heat pump

Abstract

This study addresses a reactive dividing wall column (RDWC) integrated with a vapor recompression heat pump (VRHP). The reaction applied to the system contains two consecutive transesterifications of dimethyl carbonate (DMC) and ethanol, which yields methanol (MeOH) as a by-product, ethyl methyl carbonate as an intermediate product and diethyl carbonate (DEC) as the final desired product. DEC is the only stable node of the five component reacting mixture. The location of the reaction region and feed stages affects the purity of the top product because the unstable node product is not pure MeOH but DMC-MeOH azeotrope. The VRHP pressurizes the top gas product stream and the compressed gas provides heat to the bottom stream of the ethanol recovery section. The optimization procedure minimizes the power consumption of the compressor with respect to the gas flow rate. The energy consumption in the RDWC integrated with a VRHP is reduced by 32.1% and the total utility cost is also cut by 21.6% compared with the conventional RDWC.