Experimental study of gasliquid mass transfer coupled with

Experimental study of gas-liquid mass transfer coupled with chemical reactions by digital holographic interferometry C. Wylock, S. Dehaeck, T. Cartage, P. Colinet, B. Haut 10 th Conference on Gas-Liquid and Gas-Liquid. Solid Reactor Engineering Braga, Portugal June, 26 -29, 2011 Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles

Introduction § Gas-liquid absorbers • Importance of interfacial phenomena • Classical modelling approaches: two-films, penetration, surface renewal… • Well validated by numerous experimental works … at the reactor scale ! • Few works validating at the diffusion layer scale Development of experimental tool and procedure enabling the study of gas-liquid absorption coupled with reaction at the interface scale Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 2

Experimental setup § Gas-liquid absorption performed in a Hele-Shaw cell and observed using a Mach-Zehnder interferometer § Test case: CO 2 absorption in Na. HCO 3/Na 2 CO 3 solution coupled with chemical reactions in the liquid phase Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 3

Experimental setup § Mach-Zehnder interferometer Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 4

Experimental setup § Interferograms processing (see Chem. Eng. Sc. 66, pp. 3400) n • Refractive index variations field • Horizontal averaging profiles Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 5

Mathematical modelling Schematic view of the gas-liquid absorption Gaseous phase Gas - liquid equilibrium x=0 Interface Na. HCO 3/Na 2 CO 3 aqueous solution Diffusion CO 2 + CO 3= + H 2 O ⇄ 2 HCO 3 - Chemical reactions X Depth in the liquid phase Page 6

Mathematical modelling § Mass transfer coupled with chemical reaction with § Physico-chemical parameters literature correlations § Numerical solving concentration profiles Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 7

Procedure overview Experiments Mass transfer model Refractive index variations profiles Species concentration variations profiles How to compare ? They have to be converted into a comparable variable Density variations Calibration to find correlations Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 8

Procedure overview Experiments Mass transfer model Refractive index variations profiles Species concentration variations profiles Calibration (refractometry) Experimental density variations profiles Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Simulated density variations profiles Page 9

Procedure overview Experiments Mass transfer model Refractive index variations profiles Species concentration variations profiles Calibration (refractometry) Simulated density variations profiles Experimental density variations profiles Comparison They match ? Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 10

Experiments – model comparison § Experiments compared with simulated profiles • Simulated profiles computed with physico-chemical parameters estimated by literature correlations • No match some parameters are not well estimated, especially parameters towards which the model is very sensitive Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 11

Procedure overview Experiments Mass transfer model Refractive index variations profiles Species concentration variations profiles Calibration (refractometry) Simulated density variations profiles Experimental density variations profiles Comparison They match ? Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Physico-chemical parameter fitting Page 12

Procedure overview Experiments Mass transfer model Refractive index variations profiles Species concentration variations profiles Calibration (refractometry) Simulated density variations profiles Experimental density variations profiles Comparison They match ? Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Physico-chemical parameter fitting Page 13

Procedure overview Experiments Mass transfer model Refractive index variations profiles Species concentration variations profiles Calibration (refractometry) Simulated density variations profiles Experimental density variations profiles Comparison They match Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Physico-chemical parameter fitted Page 14

Experiments – model comparison § Parameters fitted least-square fitting § Parameters : • Correlations OK for h, k 11, K 2 • New values for and , corrections for and § Matched results Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 15

Conclusions § Interferometry and procedure OK for the study of gasliquid mass absorption coupled with reactions at interface scale § Results comparable to mass transfer model provided that some physico-chemical parameters are well estimated § Perspectives Study of other systems: CO 2 in amines (scrubbing) Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 16

Thanks for your kind attention.

Experimental setup § Gas-liquid absorption performed in a Hele-Shaw cell and observed using a Mach-Zehnder interferometer § Test case: CO 2 absorption in Na. HCO 3/Na 2 CO 3 solution coupled with chemical reactions in the liquid phase Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 18

Experimental setup § Mach-Zehnder interferometer Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 19

Calibration § Link between refractive index and density • Proposed correlation: , ↳ Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles Page 20

Calibration § Link between species concentrations and density • Proposed correlation: ↳ Transfers, Interfaces and Processes Applied Science Faculty, Université Libre de Bruxelles ↳ Page 21