CO2 absorption in aqueous solutions of N-(2-hydroxyethyl)piperazine: Experimental characterization using interferometry and modeling

Abstract

This work deals with the experimental characterization of carbon dioxide (CO 2 ) absorption in an aqueous solution of N-(2-hydroxyethyl)piperazine, by using of digital holographic interferometry. This method enables visualizing the phenomena taking place in the vicinity of the gas-liquid interface.Thanks to a calibration, the obtained results yield the time evolution of the CO 2 loading field in the aqueous solution and the gas-liquid absorption rate for various operating conditions. The processing method and the obtained results are detailed. A phenomenological model, highlighting the limiting steps of the gas-liquid CO 2 absorption, is proposed. A set of experiments is realized and the parameters of this model are estimated for various initial amine concentrations and initial loadings. The results are discussed and correlations are proposed for the model parameters.

Chemical control of dissolution-driven convection in partially miscible systems: theoretical classification

“…Even if the density stratification is initially buoyantly stable, a hydrodynamic instability can develop in the gravity field if the dissolution modifies the density of the host phase. This situation can happen in solutions separated by a semi-permeable membrane 1,2 or in biphasic systems, with the dissolving phase being for instance liquid 3,4 , solid 5 , or gaseous [6][7][8][9][10][11][12][13] . Dissolution-driven convection has recently gained much interest in the context of carbon dioxide (CO 2 ) capture or sequestration [14][15][16] .…”

Experimental study of CO 2 convective dissolution: The effect of color indicators

“…The experiments are carried out in a Hele-Shaw cell, widely used in the study of CO 2 convective dissolution (Mojtaba et 2013; Wylock et al, 2011Wylock et al, , 2013Wylock et al, , 2014Thomas et al, 2014;Faisal et al, 2013;Backhaus et al, 2011;MacMinn and Juanes, 2013;Cardoso and Andres, 2014;Outeda et al, 2014;Kirk et al, 2014;Kilpatrick et al, 2011). In this confined environment, provided the gap width a between the plates is smaller than the characteristic wavelength of the pattern studied, the dynamics is analogous to that of a two-dimensional flow within a porous medium (Darcy's law), with a permeability Ä governed by the separation between the plates (Ä = a 2 /12).…”

“…This latter apparatus is made of two transparent glass or Plexiglas plates (typically a few tens of cm wide) separated by a narrow gap, generally less than 2 mm. CO 2 under subcritical (Okhotsimskii and Hozawa, 1998;Arendt et al, 2004;Song et al, 2005;Pruess, 2010, 2011;Kilpatrick et al, 2011;Wylock et al, 2011Wylock et al, , 2013Wylock et al, , 2014Faisal et al, 2013;Mojtaba et al, 2014;Thomas et al, 2014;Outeda et al, 2014;Kirk et al, 2014) or supercritical (Khosrokhavar et al, 2014) conditions is brought in contact with aqueous solutions, reactive or not, in the quasi two-dimensional space between the glass plates, in order to study the characteristics of the buoyancy-driven instability setting up in the aqueous solution upon CO 2 dissolution. Similar convective dissolution in partially miscible systems have been well characterized experimentally in other two-layer systems (Budroni et al, 2014).…”

“…The development of the convective dynamics in CO 2 -water two-layer systems can be visualized with the help of an optical technique sensitive to changes in refractive index generated by density gradients such as a Schlieren technique (Okhotsimskii and Hozawa, 1998;Arendt et al, 2004;Thomas et al, 2014;Khosrokhavar et al, 2014) or interferometry (Wylock et al, 2011(Wylock et al, , 2013(Wylock et al, , 2014Song et al, 2005). In some cases however, the presence of acidic dissolved CO 2 is detected with a color indicator sensitive to pH changes which allows to visualize the pattern with a simple camera thanks to a change in color of the fingers Pruess, 2010, 2011;Outeda et al, 2014;Kilpatrick et al, 2011;Faisal et al, 2013;Kirk et al, 2014;Mojtaba et al, 2014).…”

Experimental and numerical analysis of buoyancy-induced instability during CO2 absorption in NaHCO3–Na2CO3 aqueous solutions

“…Recently, the carbon dioxide (CO 2 ) absorption in aqueous alkaline solutions inside a Hele-Shaw cell became more and more studied in the framework of the CO 2 sequestration in deep saline aquifers (Loodts et al, 2014a,b;Javaheri et al, 2010;Kim and Choi, 2012;Kim, 2015;Riaz et al, 2006;Rongy et al, 2012;Wylock et al, 2008Wylock et al, , 2011Wylock et al, , 2013Wylock et al, , 2014. Using these HeleShaw cells, many of these studies have indeed highlighted the occurrence of a Rayleigh-Taylor (RT) instability when CO 2 is absorbed in alkaline solutions, resulting from an unstable liquid density stratification during the absorption.…”