Plant-wide modeling and analysis of the shale gas to dimethyl ether (DME) process via direct and indirect synthesis routes

A plant-wide model of the shale gas to dimethyl ether (DME) process with integrated CO2 capture via direct and indirect synthesis routes has been developed in Aspen Plus V8.4®. In this study, models of the pre-reforming reactor, autothermal reforming (ATR) reactor and DME synthesis reactors using kinetic data have been developed. For CO2 capture, Rectisol and methyl diethanolamine (MDEA)/piperazine (PZ) technologies have been evaluated and results have been compared with the experimental data. A novel DME separation process has been developed and evaluated for efficient separation of DME, syngas, and CO2. Binary interaction parameters for the vapor-liquid equilibrium (VLE) model of the methanol-DME-CO-CO2-H2O-H2 system are regressed using the experimental data. Effects of the key parameters like CO2 recycle ratio and H2/CO ratio on the utility consumption in the syngas synthesis unit, acid gas removal (AGR) unit, DME synthesis unit and DME separation unit are studied. It is observed that the direct shale gas to DME production process operated with an optimal H2/CO ratio of 1 has a higher DME yield and overall equivalent electrical efficiency than the indirect shale gas to DME production process.