Influence of CO2 partial pressure on mass transfer

“Increasing the CO2 partial pressure in the gas feed to the absorber column has two effects on KGCO2aV. First, increasing the CO2 partial pressure can lead to an increase of the partial pressure gradient83 because of the consummation of more actively free-amine molecules and, as a result, a decrease of KGCO2aV can occur (according to eqn (2)). Second, increasing the CO2 partial pressure can intensify the gas flow turbulence in the absorber column and, as a result, increase KGCO2aV.84 In the above-mentioned reviewed works, researchers showed that by increasing the CO2 partial pressure in the gas feed, KGCO2aV decreased. This effect shows that amine solutions, especially those which have higher reaction kinetic constant values (such as MEA or PZ), have good performance under lower partial pressure than under higher partial pressure.85,86 This effect indicates that amine solutions have a high CO2 removal efficiency in a lower partial pressure of CO2 in the gas feed. This occurrence shows that the liquid phase resistance dominates the mass transfer performance of absorption into amine solutions.87

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