Simulation study on the design of a 3D-printed vapor-liquid separator with integrated heat recovery for CO2-based methanol synthesis

For methanol synthesis from carbon dioxide, efficient product removal and further conversion of unreacted feedstock are crucial due to low single-pass equilibrium conversions. Condensing the reactor outlet effectively separates liquid products from the gaseous feedstock. Since reactor temperatures typically exceed 200 °C, cooling is required for condensation to occur, making efficient heat recovery essential for viable process economics. Instead of using separate heat exchangers and flash drums, integrating their functionalities into multipurpose equipment can reduce process units. Additive Manufacturing offers a solution for creating such highly integrated devices, but the high level of integration complicates the design, as altering one geometric parameter affects the entire unit. To streamline the design process, we developed a computational fluid dynamics model addressing fluid flow, heat exchange, phase transfer, and species balances concurrently. By focusing on an easily adjustable, simplified representation of a repetitive core element of a 3D-printable unit, we achieved reasonably fast solution times, allowing for sufficient simulation variations for the unit design. Sensitivity analyses of nine geometric parameters for a lab-scale device demonstrated that separation of an equilibrium product mixture at 250 °C and 50 bara, close to the thermodynamic phase composition at 15 °C, is possible while reheating the remaining gas above 245 °C. A real unit, informed by these data, was 3D-printed using metal laser powder bed fusion. Furthermore, the simulations facilitated rapid design adaptations for an upscaled device compatible with state-of-the-art industrial 3D printers, capable of processing a 50 kg h −1 reactor outlet and suitable for decentralized plant operations. • Combination of heat transfer and phase separation in CFD • CFD-model for a parameterized, 3D-printable, highly integrated process unit • Influence of nine different geometry parameters on separation and heat exchange