Experimental and modelling study of CO 2 sorbent for Ca-Cu chemical looping process

Transcription

1 Experimental and modelling study of CO 2 sorbent for Ca-Cu chemical looping process M. Martini, F. Gallucci, M. van Sint Annaland Chemical Process Intensification, Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands

2 Outline Introduction: Ca-Cu process Experimental setup Experimental results Kinetic model Preliminary modeling results Conclusions 2

3 Ca Cu looping process Introduction SER based process. Heat required for CaCO 3 calcination supplied through CuO reduction SER stage Produced at high pressure Carried out at high pressure to limit calcination CaCO 3 Calcination/ Reduction of CuO Cu oxidation Carried out at low pressure to avoid high calcination temperature

4 Introduction Sorption Enhanced Reforming: H 2 + H 2 O N 2 CO 2 + H 2 O CH H O CO 3H CO H2O CO2 H2 CaO CO CaCO 2 3 A Cu CaO N 2 B Cu CaCO 3 B CuO CaCO 3 C CuO CaCO 3 Operating conditions: Reaction front P = 2-3 bar T = 6-7 ⁰C Cu CaCO 3 CuO CaCO 3 Cu CaO CH 4 + H 2 O A N 2 CO, H 2 or CH 4 B Air Study the carbonation reaction at high pressure 4

5 Experimental setup Rubotherm magnetic suspension balance Operating conditions: - T = up to 12 o C - P = up to 3 bar Quartz porous basket Gas Dosing System (max flow rate: 5 ml/min) 5

6 Conversion calculation from TGA results Experimental setup 1 MWCaO Carbonation conversion, X % % weight increase (t) w MW CaO CO 2 6

7 Experimental results Experimental conditions Material used: - CaO-based solid: 41% wt of CaO on Ca 12 Al 12 O 33 - Particle size 1 μm What has been measured: - Stability test at high and low pressure - Effect of carbonation temperature - Effect of total pressure at constant partial pressure of CO 2 - Effect of partial pressure of CO 2 at constant total pressure 7

8 Final conversion Experimental results Final conversion Cyclic stability Cycle number Cycle number P = 1 bar T carb = 7 ⁰C T calc = 85 ⁰C p CO2 =.15 bar (carbonation) P = 1 bar T carb = 7 ⁰C T calc = 85 ⁰C p CO2 =.4 bar (carbonation) 8

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10 CaO conversion (-) CaO conversion (-) Effect of partial pressure Experimental results bar.4 bar.3 Pt=6 bar Pt=1 bar.4 Pt=1 bar.3 Pt=1 bar Time (s) Time (s) P = 6 bar T carb = 7 ⁰C T calc = 85 ⁰C P = 1 bar T carb = 7 ⁰C T calc = 85 ⁰C 1

11 CaO conversion (-) Kinetic model Chemical reaction control Time (s) Random pore model (Bathia and Perlmutter) dx dt eq 1 1 ln 1 kss C C X X P Z P ln 1 X 1 2ka s 1 n Structural parameter Pressure term M CaO bd S p Diffusion through the product layer Chemical reaction control: dx dt eq 1 X 1 ln 1 X kss C C P 1 P n S. K. Bathia, D. D. Perlmutter, A Random Pore model for Fluid-Solid Reactions, 198, AlChE Journal 11

12 Relative pore volume (mm 3 g -1 ) Structural parameter 4L 1 S 2 Kinetic model Porosity: Pore length: Surface area: () r dr L 2 r S () r dr () r 2 dr r Pore volume distribution.65 L m m 14 3 S m m Pore volume distribution from Hg-porosimetry pore diameter (nm) 12

13 Effect of temperature Preliminary modeling results - - model experiments P = 2 bar p CO2 =.4 bar T calc = 85 ⁰C 13

14 Effect of total pressure Preliminary modeling results - - model experiments p CO2 =.4 bar T carb = 7 ⁰C T calc = 85 ⁰C n 1 14

15 Conclusions Conclusions From experimental study: Material stable after several cycles both at low and high pressure Final conversion increases increasing the carbonation temperature Kinetic slower at higher total pressure Kinetic faster at higher partial pressure of CO 2 From modeling study: Random pore model can be used to describe the carbonation reaction and the pressure effect Deeper investigation required to better understand the material behavior 15

16 Acknowledgements The ASCENT project as part of the European Union s Seventh Framework Programme (FP7/27-213) under grant agreement nº Note: "The present publication reflects only the authors views and the European Union is not liable for any use that may be made of the information contained therein. Thank you for your attention Michela Martini: M.Martini@tue.nl 16