Experimental study on partial oxy-combustion technology in a bench-scale CO2 capture unit

The reduction of CO2 emissions from anthropogenic sources in this century will require a higher reliance on carbon capture and storage (CCS) technologies. Post-combustion based on a regenerative chemical absorption is considered a mature and close-to-market option in near and mid-term. However, the high energy penalty related to solvent regeneration and solvent degradation are two of the main drawbacks hindering the deployment of this technology. Partial oxy-combustion is considered a promising CCS technology that can substantially decrease the reboiler duty due to the increase on the CO2 partial pressure in the flue gas and hence the driving force in the absorber compared to conventional post-combustion approaches. This work explores the potentialities of partial oxy-combustion in a bench-scale CO2 capture unit to evaluate the benefits on the CO2 separation stage. The experimental facility consists of a regenerative CO2 chemical absorption process with a CO2 removal capacity of 0.48 kg/h. The most relevant operating parameters such as temperature, CO2 loading and L/G ratios were evaluated under variations of the CO2 concentration of the flue gas, ranging between 15% v/v and 60% v/v CO2, in order to obtain the optimal reboiler duty associated to the solvent regeneration. Results showed that the use of four packing bed improved the CO2 absorption performance. Although the optimal L/G ratios were moved to higher values, they also achieved CO2 removal efficiencies over 95% and lower energy consumptions compared with the baseline case (post-combustion). Experiments carried out using a 60% v/v CO2 in the flue gas provided 95.7% of CO2 removal efficiency and the lowest reboiler duty (4.74 GJ/t CO2) which resulted in a 57% reduction of the specific energy consumption compared with the post-combustion run.