A multi-criteria optimization and decision-making framework of green DME reactor configurations with a focus on high productivity and low CO2 emission rate

Abstract

The combination of a conventional Dimethyl Ether (DME) reactor with hydrogen perm-selective membrane and effluent recycling creates innovative membrane reactor (MR) configurations that can efficiently improve thermodynamic limits plus low kinetic rates. In the present article, two eco-friendly configurations were applied to the DME conventional reactor (CR) to boost the DME production rate, yield, and selectivity. These configurations comprise two concentric pipes in which in the 1st configuration the fresh synthesis gas is fed to the inner tube side, hydrogen permeates through the reaction zone, and finally the effluent is recycled back to the outer tube, while in the 2nd one, the effluent of outer tube recycled to the inner pipe. The comprehensive 1-D heterogeneous model has an excellent agreement with industrial data. Also, the simulation results reveal that the higher temperature profile in the 2nd configuration is the consequence of more intensification in the reaction zone by H2 injection and proper heat removal which leads to around 9.5 %, 8.22 %, and 10 % increases in the DME production rate, selectivity, and yield compared to CR, respectively. Enjoying reaction output recycling and H2 permeation, the reaction rate of CO and CO2 hydrogenation plus methanol dehydration enhances significantly in the 2nd scheme.According to Euclidean Distance, the optimization results show that the MODE algorithm has a better performance compared to NSGA-II to obtain optimal Pareto Front and also more rapid respect to lower computational time. The LINMAP approach provides a minimum deviation index among all three decision-making algorithms. Employing optimal operation conditions leads to an enhancement of 17 %, 47 %, and 36 % in DME production rate, selectivity, and yield compared to CR. This eco-friendly configuration prevents the emission of 22000 tons of per year CO2 to the atmosphere.