Experimental study of CO 2 absorption dynamics in an aqueous amine solution using Mach-Zehnder interferometry

Transcription

1 Experimental study of CO 2 absorption dynamics in an aqueous amine solution using Mach-Zehnder interferometry C. Wylock, S. Dehaeck, D. Alonso, P. Colinet and B. Haut GLS - 11 Coex, Seoul, Korea August, the 21 st, 2013

2 Framework CO 2 capture by aqueous amine solution 2

3 Framework Screening of amines wanted: Fast reactivity with CO 2 High absorption capacity Low energy (heating) regeneration cost High stability This work : Experimental tool and modeling of the CO 2 absorption Applied on a new generation amine: N-(2- hydroxyethyl)piperazine (HEP) as a test case 3

4 Outline Framework Experimental setup Calibration Phenomenological modeling Results and discussion Conclusion and perspectives 4

5 Experimental setup Gas-liquid contactor: Hele-Shaw cell Pure CO 2 flowing at the interface Amine-CO 2 reactions in the liquid Gas openings CO 2 Cover Hele-Shaw cell Cell mount HEP aqueous solution CO CO 2 2 CO 2 CO 2 CO CO CO 2 CO 2 2 CO 2 2 CO 2 5

6 Experimental setup Gas-liquid contactor: Hele-Shaw cell Pure CO 2 flowing at the interface Amine-CO 2 reactions in the liquid Refractive index variations Gas openings CO 2 Cover Hele-Shaw cell Cell mount HEP aqueous solution CO CO 2 2 CO 2 CO 2 CO CO CO 2 CO 2 2 CO 2 2 CO 2 5

7 Experimental setup Absorption visualization by Mach-Zehnder interferometer CCD Camera Mirror 1 Gas Interface Liquid 6

8 Experimental setup Absorption visualization by Mach-Zehnder interferometer 7

9 Experimental setup Absorption visualization by Mach-Zehnder interferometer 7

10 Experimental setup Image post-processing to get time evolution of refractive index variation fields 8

11 Experimental setup Image post-processing to get time evolution of refractive index variation fields 8

12 Experimental setup Time evolution of refractive index variation profiles Horizontal averaging in a window Refractive index variation profiles Gas phase Liquid phase 9

13 Experimental setup Time evolution of refractive index variation profiles Horizontal averaging in a window Refractive index variation profiles Gas phase Absorbed CO 2 Liquid phase 9

14 Outline Framework Experimental setup Calibration Phenomenological modeling Results and discussion Conclusion and perspectives 10

15 Calibration Refractometry Measure of refractive index of solutions with various: Initial HEP concentration : [HEP] 0 Absorbed CO 2 amount : [HEP] 0 q 0 11

16 Calibration Refractometry Measure of refractive index of solutions with various: Initial HEP concentration : [HEP] 0 Absorbed CO 2 amount : [HEP] 0 q 0 Proposed relation: n = n w + μ HEP HEP 0 + μ θ HEP 0 θ 0 Conversion: Δθ x, t = Δn x, t μ θ HEP 0 m mol m3 mol 11

17 Outline Framework Experimental setup Calibration Phenomenological modeling Results and discussion Conclusion and perspectives 12

18 Phenomenological modelling Experimental behaviour [HEP] 0 = 1000 mol/m 3 No initial loading Δθ x, t = Δθ 0, t erfc x 2 D t Δθ 0, t = Δθmax 1 exp k t Δθ x, t = Δθmax 1 exp k t erfc x 2 D t 13

19 Phenomenological modelling Parameter fitting Δθ x, t = Δθmax 1 exp k t erfc x 2 D t 14

20 Outline Framework Experimental setup Calibration Phenomenological modeling Results and discussion Conclusion and perspectives 15

21 Results and discussion Time evolution of absorbed CO 2 amount T CO2 t = HEP 0 θ x, t dx 0 T CO2 t = 2 HEP 0 Δθmax D t π 1 exp k t Fastest absorption rate is not reached for the highest [HEP] 0! The absorption rate increases with a decrease of the initial loading 16

22 Results and discussion Parameter fitting Fitting results k = 0.27! θmax= 87.6 HEP θ Probably decrease of CO 2 solubility? D = HEP θ ! Limitation by amine mobility because viscosity increases 17

23 Results and discussion Simulated evolution of absorbed CO 2 amount T CO2 t = 2 HEP 0 Δθmax D t π 1 exp k t 18

24 Outline Framework Experimental setup Calibration Phenomenological modeling Results and discussion Conclusion and perspectives 19

25 Conclusion Gas-liquid CO 2 absorption in aqueous HEP solution in Hele-Shaw cell using a MZI enables absorption visualization at interface scale Phenomenological model emulating the loading profiles analytical expression for CO 2 absorption dynamic Estimation of model parameters for various concentrations and analysis of trends Absorption rate controlled by molecules mobility in the solution focus not only on the reaction kinetic but also on the diffusivity 20

26 Perspectives Determination of the actual chemical reaction scheme for the CO 2 -HEP system (ongoing) Determination of the link between the phenomenological model parameters Δθmax, k and with the actual physico-chemical parameters (diffusivities, solubility, equilibrium and kinetic constants) D 21

27 Thanks for your kind attention 22