Methanol Recovery from CO2/CH4 Co-Valorization: Process Simulation, Separation Performance and Techno-Economic Assessment of the Distillation Process

The efficient recovery of methanol is essential for improving the overall performance and economic viability of integrated carbon dioxide utilization processes. This work presents the simulation of the process, separation performance and techno-economic evaluation of the methanol recovery section of an integrated CO2/CH4 co-valorization process for dimethyl ether (DME) production using ChemCAD. In an attempt to assess the recovery of methanol (MeOH) from the methanol-rich stream obtained after dimethyl ether separation, a rigorous equilibrium-based distillation model was developed following a preliminary shortcut column design. The separation train was composed of flash separation and rigorous staged distillation. The operating conditions were centered on maximizing methanol recovery with stable column operation. The developed model achieved a MeOH recovery of 98.39% (overhead = 99.60 wt.% MeOH), specifically 420.73 kg/h in the distillate stream and efficient rejection of water to the bottom stream. Under the chosen operating conditions, the reboiler duty and condenser duty were 900.86 MJ/h and 1050.86 MJ/h, respectively. The specific energy consumption was 4.64 MJ/kg of recovered methanol. The equipment costing analysis calculated the total purchase cost of US$ 114,086 and installed cost of US$ 312,818 for the recovery column, condenser and reboiler. Screening calculations, performed one at a time, showed that a change in the price of steam has a bigger influence on annual utility spending than an equal proportional rise in the price of cooling water which correlates to solely the methanol recovery section.