(96b) Influence of Particles on Amine Losses during CO2 Capture: A Process Simulation Coupled Aerosol Dynamics Model

Efforts to reduce the concentration of atmospheric CO₂ have been initiated due to escalating concerns of global warming and climate change. Amine-based post-combustion CO₂ capture offers an economically viable retrofit for power-plants to help combat these emissions. However, solvent losses have been a major challenge to commercializing this technology. Recent experiments¹ show that vapor-based and aerosol-based solvent losses are the key mechanisms of amine solvent loss during CO₂ capture. While vapor-based amine losses can be abated by employing techniques like water-washing, there has been little work to curtail aerosol-based solvent losses. This is primarily because the underlying mechanisms governing these losses are still not well understood. Although there are a few numerical models proposed for this system, there are no models that consider aerosol phenomena such as coagulation or particle loss. Moreover, these models have not been fully validated through experiments.

In this work, a process simulation model for multi-component mass and heat transfer, hydrodynamics, thermodynamics, and electrolytic-solution chemistry was coupled with a multi-component aerosol dynamics model accounting for condensation, coagulation, and particle loss. The model’s outputs were validated using the experimental data of Khakharia et al., 2013². Based on the results, it was shown that neglecting particle losses inside the absorber resulted in over-prediction of amine-based solvent losses, while including coagulation resulted in reduced (~10%) emissions. Also, amine emissions increased with higher particle number concentration and lower initial mean particle size. Furthermore, it was shown that amine emissions decreased with lower solvent concentrations and temperatures, but CO₂ capture efficiency dropped for decreasing solvent concentration while remaining unchanged for lower temperatures. With this model, optimum operating conditions are suggested to reduce solvent losses during amine-based CO₂ capture.

References

1. International Journal of Greenhouse Gas Control, vol. 85, pp. 86-99, 2019.
2. International Journal of Greenhouse Gas Control, vol. 19, pp. 138-144, 2013.