Experimental Investigation of the Onset of Convection During CO2- N2 Mixture Dissolution in Brine

High cost of CO2 purification from the flue gas is an essential barrier to CO2 sequestration projects, especially for conventional power plants. However, N2 is the most dominant impurity in the flue gas of power plants, but there is no experimental work to examine the effect of N2 impurity on the dissolution behavior of CO2 in brine. Since N2 impurity reduces the solubility of CO2 in brine, therefore the available theoretical works concluded the later onset of convection for CO2- N2 mixture in comparison of pure CO2. For the first time, a high pressure Hele- Shaw cell is designed and constructed in this study to examine the dissolution of CO2- N2 mixture through the qualitative (image) and quantitative (pressure decay) measurements which helps to obtain the whole understanding from process progressing. With analyzing the experimental data, effective diffusion coefficient of CO2 is introduced as a missing concept in previous theoretical studies. In the examined condition, it has been shown that 90%CO2-10%N2 mixture represents earlier onset of convection with higher critical wave number than pure CO2 experiments. It is an interesting finding which can help to tackle the possible barriers about impure CO2 sequestration and reduce the cost of projects.