Ionic Liquids for Post Combustion CO 2 -Absorption

Transcription

1 Ionic Liquids for Post Combustion CO 2 -Absorption 12th MEETING of the INTERNATIONAL POST-COMBUSTION CO 2 CAPTURE NETWORK David Wappel 1), Guenter Gronald 2), Roland Kalb 3) and Josef Draxler 1) 1) University of Leoben, Institute of Process Technology and Industrial Environmental Protection, Austria 2) AE&E Austria GmbH & Co KG 3) proionic Production of Ionic Substances GmbH 29th September - 1st October 2009 Regina, Canada

2 Target of the Work To investigate the ability of various task specific ionic liquids (ILs) as potential CO 2 capture solvents for PCC Comparison of one selected task specific ionic liquid to the reference solvent MEA Slide 2

3 Laboratory Work: Content t of the Work Screening of ionic liquids for a quick evaluation of the CO 2 absorption performance Vapor-liquid equilibrium measurements Calculation of the enthalpy of absorption Calculation l of the energy demand d for stripping i Pilot Plant Testing: Direct comparison of MEA and IL under real flue gas conditions Slide 3

4 Why Ionic Liquids? Chemical Looping Biological Processes Advanced Amine Solvents Solid Sorbents Membranes Systems MOFs Enzymatic Membranes Amine Solvents Physical Solvents Cryogenic Oxygen Advanced Physical Solvents Post Combustion Pre-Combustion Oxy Combustion (Figueroa et al. 2008) Slide 4

5 Ionic Liquidsid Ionic liquids are salts with a melting temperature below the boiling point of water. Most ionic liquids ids have an organic cation and an inorganic anion. (Wasserscheid und Welton, 2008) Advantages: Application without any solvent possible Myriad different structures and variation possibilities of anion and cation Non measurable vapor pressure Disadvantages: High Viscosity Currently high costs Little Experience Slide 5

6 Screening Experiments Fast investigation of CO 2 absorption 2 performance with a small amount of liquid. Reference solvents 30w% Monoethanolamine (MEA) 30w% Potassium Carbonate (K 2 CO 3 ) Test of CO 2 absorption at 25 C and 80 C Qualitatively determination of the absorption kinetics Slide 6

7 Screening Experiments 80 different ILs or IL-blends were tested Pure ILs (without additive) High viscosity Low CO 2 absorption performance Slow absorption kinetics Water as an additive Better absorption performance Slide 7

8 Screening Experiments Solvent 30w% MEA in water 48w% IL 8 in water 30w% K 2 CO 3 in water Δp 25 [mbar] Δp 80 [mbar] t 25 [sec] t 80 [sec] Slide 8

9 Viscosity of the ionic liquid water blend depending on the water content C 50 C 388,4 mpas] c Viscosity [ Dynami ,6 7,6 20,8 58,8 54,6 0 50% 55% 60% 65% 70% w% Ionic Liquid Slide 9

10 Vapor-Liquid id Equilibrium i (VLE) Measurements Basis for energy demand calculation Validation with MEA and comparison with the literature VLE Measurements of IL between 40 C und 110 C Austgen et al. (1991) and Ma mum et al. (2005; 2007) Slide 10

11 Vapor-Liquid id Equilibrium i Curves Slide 11

12 Enthalpy of Absorption ΔH abs Changing g of equilibrium with temperature expressed with van t Hoff equation dln k dt ΔH ln Abs pco 2 = Δ H = 2 Abs R R T 1 T For the analyzed ionic liquid kj Δ H Abs = 41.1 ± 3.2 mol α Slide 12

13 Energy Demand for the CO 2 Stripping i Calculation for 30w% MEA and 60w% IL Validation ld of model with MEA literature Different process parameters: Mean deviation only 1,3% Standard process parameters CO 2 -Concentration Flue Gas 13,3 vol% CO 2 Capture Rate 90 % IL Concentration 60 w% MEA Concentration 30 w% Temperature Absorber 40 C Desorption Temperature 110 C Slide 13

14 Energy Demand for the CO 2 Stripping i Simplifications No temperature dependency of enthalpy of absorption Comparison of standard PCC process with obtained VLE data not very detailed optimization of the CO 2 absorption process Calculations are based on equilibrium conditions no kinetic effects Slide 14

15 Energy Demand for the CO 2 Stripping i 60w% Ionic Liquid in water Equilibrium data from experiment 30w% MEA in water Calculation Stages absorption Stages desorption Solvent loading inlet absorber [mol CO2 /mol Solvent ] 0,65 0,68 0,242 0,242 Heat of absorption Dh abs [kj/mol CO2 ] 41,1 41, Solvent flow rate required [m³/ton CO2 ] ,5 14,5 Thermal heat requirement [GJ/ton CO2 ] 4,18 3,43 4,78 4,12 Slide 15

16 Laboratory Work Summery Ionic Liquids have a potential for post-combustion CO 2 capture Energy demand is slightly better than MEA Solvent Flow rate is higher h than for MEA solution Drawbacks of ILs High viscosity of pure ionic liquids Slower kinetics No operational experience for PCC High price (production of small amounts) Slide 16

17 Pilot Plant Testing Maintain operational experience Long term stability (Degradation) Corrosion Absorption kinetics Pilot plant performance Small pilot plant for post combustion CO 2 capture Direct comparison of MEA and IL Slide 17

18 Hard coal fired power plant CO 2 Pilot Plant Characteristics ti V Gas = 20 Nm³/h d Abs =15cm d Des = 12 cm Fully instrumented Fully balanceable Slide 18

19 CO 2 Pilot Plant Testing Experiments with 30w% MEA solution Stable conditions Demonstrate the functionality of the pilot plant Average capture rate of 85-90% Energy demand ~ 4.2 GJ/t CO2 Ionic liquid tests are scheduled in October 2009 Direct comparison of MEA and IL considering energy demand and capture performance at real conditions Slide 19

20 Acknowledgement The authors thank the Federal Ministry for Transport, Innovation and Technology (BMVIT), the Federal Ministry of Economy, Family and Youth (BMWA) and the Austrian Research Promotion Agency (FFG) for their financial support. Slide 20

21 Thanks for your attention!! David Wappel David Wappel