New Pilot Data and Aspen Plus Simulations for CO2 Capture with MDEA/PZ: A Biogas Upgrading Case

Abstract

This work introduces robust pilot-scale experimental campaigns to validate the predictive capabilities of the current rate-based ENRTL-RK Aspen Plus model for CO2 capture using MDEA/PZ solvent blends under biogas upgrading conditions. The experiments were conducted in a pilot absorber column (height: 10.5 m, diameter: 0.1 m) equipped with 8.2 m Mellapak 250Y packing with an 84 mm packing diameter to upgrade gas streams containing roughly 40 vol% CO2. Key operating parameters, including lean-to-gas flow rate, lean solvent temperature, and the PZ-to-MDEA ratio, were systematically varied to study their influence on CO2 slip and mass transfer performance. The campaigns provided the first pilot-scale dataset available for validating this model, addressing a critical gap identified in the Aspen Plus model description. The model demonstrated good agreement with steady-state data, accurately predicting CO2 absorption trends along the absorber column. However, sensitivity studies revealed opportunities to refine the mass transfer coefficient for improved prediction accuracy. These findings emphasize the value of validated simulations at the pilot scale in optimizing CO2 capture processes for biomethane production.

Keywords: CO2 capture, biogas upgrading, pilot scale, piperazine (PZ), methyldiethanolamine (MDEA), rate-based modelling