10 th Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering Braga, Portugal

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

10th Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering Braga, Portugal June, 26-29, 2011

Transfers, Interfaces and ProcessesApplied 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


Experimental setup

Gas-liquid absorption performed in a Hele-Shaw cell and observed using a Mach-Zehnder interferometer

Test case: CO2 absorption in NaHCO3/Na2CO3 solution


coupled with chemical reactions in the liquid phase

Experimental setup

Mach-Zehnder interferometer


Experimental setup

Interferograms processing (see Chem. Eng. Sc. 66, pp.3400)• Refractive index variations field• Horizontal averaging profiles


n

Mathematical modelling

Schematic view of the gas-liquid absorption

Interface

Gaseous phase

NaHCO3/Na2CO3 aqueous solution

x=0 Gas - liquidequilibrium

Diffusion

Chemical reactions

XDepth in the liquid phase

CO2 + CO3= + H2O ⇄ 2 HCO3-

Mathematical modelling

Mass transfer coupled with chemical reaction

Physico-chemical parameters literature correlations

Numerical solving concentration profiles


with

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 variationsCalibration to find correlations

Procedure overview





Calibration(refractometry)

Experimental density variations

profiles

Simulated density variations profiles

Procedure overview







profiles


Comparison

They match ?

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


Procedure overview







profiles


Comparison

They match ? Physico-chemical parameter fitting

Procedure overview







profiles


Comparison

They match Physico-chemical parameter fitted

Experiments – model comparison

Parameters fitted least-square fitting

Parameters :• Correlations OK for h, k11, K2• New values for and ,corrections for

and Matched results


Conclusions

Interferometry and procedure OK for the study of gas-liquid 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: CO2 in amines (scrubbing)


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: CO2 absorption in NaHCO3/Na2CO3 solution


coupled with chemical reactions in the liquid phase

Experimental setup

Mach-Zehnder interferometer


Calibration

Link between refractive index and density• Proposed correlation:


,

↳

Calibration

Link between species concentrations and density• Proposed correlation:


↳↳

10 th Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering Braga, Portugal

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