Application of triply periodic minimal surface (TPMS) structures for bioenergy with carbon capture and storage processes

Sammanfattning

As carbon removal technologies become essential for meeting global climate targets, Bioenergy with Carbon Capture and Storage (BECCS) has emerged as an important pathway for achieving net-negative emissions. This thesis investigates the performance of Triply Periodic Minimal Surface (TPMS) Gyroid structures as a novel packing material for post-combustion CO₂ capture. Using a lab-scale absorption column with a 1.5 m packed height, the study experimentally evaluates the CO₂ absorption efficiency of 85% porosity Gyroid structures using an unpromoted aqueous K₂CO₃ solvent. The influence of five operating parameters was systematically investigated: liquid flow rate, gas flow rate, solvent concentration, liquid temperature, and inlet CO₂ concentration. Increasing the liquid flow rate increased absorption efficiency from 8.98% to 37.64%, which was attributed to improved wetting and enhanced liquid-side mass transfer. Increasing the gas flow rate reduced absorption efficiency from 68.90% to 31.75% due to shorter gas residence time in the column. Solvent concentration showed a non-linear trend, where efficiency increased from 29.89% at 10 wt% to a maximum of 39.36% at 25 wt%, before decreasing at 30 wt% as increased viscosity and reduced diffusivity limited mass transfer. Increasing the liquid temperature from 30 to 50 °C improved absorption efficiency from 37.64% to 54.76%, due to enhanced reaction kinetics and increased diffusivity. In contrast, inlet CO₂ concentration had only a minor influence on absorption efficiency, which remained relatively constant across the tested range. Compared with previous smaller-scale studies using a shorter packed column, the present system demonstrated substantially higher absorption efficiencies for all investigated parameters, confirming the importance of residence time and gas–liquid contact in kinetically limited carbonate absorption systems