Density modelling NH 3 -CO 2 -H 2 O liquid mixtures. Technology for a better society

Size: px

Start display at page:

Download "Density modelling NH 3 -CO 2 -H 2 O liquid mixtures. Technology for a better society"

Kelley Eaton
5 years ago
Views:

1 1 Density modelling NH 3 -CO 2 -H 2 O liquid mixtures

2 2 Liquid density model in Aspen Plus Clarke model (for aqueous electrolyte molar volume) Molar volume for electrolyte solutions (V m l ), applicable to mixed solvents Based on apparent components V l m (298.15K) = x w V,l w + x am V,l am + 2x w x am K w,am V,l,l 0.5 w V am + 2xw x c K w,c V,l,l w V 0.5 c + 2x am x c K am,c V,l,l am V 0.5 c + x BC V BC + x CM V CM + x CB V CB V m l (T) = V m l (298.15K) V l s liquid molar volume for solvent mixtures based V l on liquid volume quadratic mixing rule s (T) V s l (298.15K) Non-electrolyte apparent components (molecular solvents): V e l liquid molar volume for electrolytes H 2 O (w) NH 3 (am) CO 2 (c) Electrolyte apparent components (ca): DIPPR equation for the computation of the pure component liquid molar volume: V W,l, V am,l and V c,l NH 4 HCO 3 (BC) NH 4 NH 2 COO (CM) (NH 4 ) 2 CO 3 (CB) x BC +x CM +x BC V ca = V ca + A ca, with x 1+ x BC +x CM +x w + x am + x c + x BC + x CM + x CB = 1 BC and where x i is computed from the true ionic concentrations 9 parameters to be estimated: K w,am, K w,c, K am,c, V BC, A BC, V CM, A CM, V CB, A CB

3 3 Default (Aspen Plus) liquid density model validation Default value of parameters: K w,am = 0 K w,c = 0; K am,c = 0 V BC = m3 A BC = m3 V CM = m3 A CM = m3 V CB = m3 A CB = m3 If experimental data obtained at P vap > P atm and T < 0 C are not considered, the density is underestimated up to 20% Perkin (1889) -20% 3.9 T( C) 15.0 Perry s chemical engineers handbook 0 T( C) 25.0 Liu et al. (2012) 10.0 T( C) 50.0 Lichtfers (2000) 39.9 T( C) 80.1 This work (Lab samples) T C = 27.0 This work (Pilot plant samples) m NH3 0.6 m NH3 1.5 m NH3 1.9 m NH3 m NH T( C) m NH3 mol NH3 = = 17.7 CO 2 loading CO 2 loading CO 2 loading mol CO2 mol CO2 mol CO2 = 0 = 0 = 0 0 CO 2 loading mol CO2 mol NH CO 2 loading mol CO 2 mol NH3 = CO 2 loading mol CO 2 mol NH Perkin. J Chem Soc 55 (1889) 680 Perry et al. Perry s chemical engineers handbook, 8th ed.; McGraw-Hill: New York, 2008 Liu et al. J Chem Eng Data 57 (2012) Technology Lichtfers (2000) for a better society

4 4 Liquid density modelling NH 3 -H 2 O mixtures Regressed parameter: K w,am = ± K w,c = 0; K am,c = 0 Average absolute relative deviation: AARD % = 100 Absolute average deviation: AAD kg m 3 = 1 N N N i=1 N i=1 ρ exp,i ρ calc,i ρ exp,i ρ exp,i ρ calc,i Density regression of unloaded aqueous NH 3 solutions from the literature [1,2,3,4] using experimental data obtained at T 0 C and with P vap < P atm Perkin (1889) 3.9 T( C) 15.0 m NH3 = 26.5 CO 2 loading mol CO2 = 0 Perry s chemical engineers handbook 0 T( C) m NH CO 2 loading mol CO2 = 0 Liu et al. (2012) 10.0 T( C) m NH CO 2 loading mol CO2 = 0 Lichtfers (2000) 40.0 T( C) m NH CO 2 loading mol CO2 = 0 AARD = 0. 4% max ARD = 1. 5% AAD = 3. 6 kg m3 max AD kg = m 3 [1] Perkin. J Chem Soc 55 (1889) 680 [2] Perry et al. Perry s chemical engineers handbook, 8th ed.; McGraw-Hill: New York, 2008 [3] Liu et al. J Chem Eng Data 57 (2012) Technology [4] Lichtfers (2000) for a better society

5 5 Liquid density modelling CO 2 -NH 3 -H 2 O mixtures Fixed parameters: K w,am = ± K w,c = 0 K am,c = 0 Regressed parameters: V BC = ± m3 A BC = ± m3 V CM = ± m3 A CM = 0.09 ± 0.04 m3 V CB = 0.12 ± 0.05 m3 A CB = 0.2 ± 0.3 m3 Density regression of CO 2 -loaded aqueous NH 3 solutions from the literature [1] using experimental data obtained at T 0 C and with P vap < P atm Lichtfers (2000) 39.9 T( C) m NH3 mol NH CO 2 loading mol CO AARD = 0. 1% max ARD = 0. 6% AAD = 1. 0 kg m3 max AD kg = 5. 8 m 3 But highly correlated parameters with high standard deviation in some cases Additional experiments might be required for modelling [1] Lichtfers (2000) 5

6 6 Liquid density model validation Regressed parameters: K w,am = K w,c = 0; K am,c = 0 V BC = m3 A BC = m3 V CM = m3 A CM = 0.09 m3 V CB = 0.12 m3 A CB = 0.2 m3 Model validation with independent liquid density measurements of the samples taken during the pilot plant tests of the CO 2 absorber This work (Lab samples) T C = 27.0 m NH3 mol NH3 This work (Pilot plant samples) 11.9 T( C) m NH3 = 17.7 CO 2 loading mol CO 2 mol NH3 = CO 2 loading mol CO The model consistently underpredicts the experimental liquid density values, but always below 2% AARD = 0. 6% max ARD = 1. 8% AAD = 6. 9 kg m3 max AD kg = m 3

7 7 Density model for CO 2 -NH 3 -H 2 O liquid mixtures Perkin (1889) Perry s chemical engineers handbook Liu et al. (2012) Lichtfers (2000) This work (Lab samples) -20% This work (Pilot plant samples) Default Aspen (Thomsen) AARD, % (max) 7.3 (21.1) ARD, kg/m 3 (max) 77.2 (243.6) This work (Thomsen) 0.5 (1.8) 5.5 (18.5) Average absolute relative deviation: AARD % = 100 N Absolute average deviation: AAD kg m 3 = 1 N N i=1 N i=1 ρ exp,i ρ calc,i ρ exp,i ρ exp,i ρ calc,i Perkin. J Chem Soc 55 (1889) 680 Perry et al. Perry s chemical engineers handbook, 8th ed.; McGraw-Hill: New York, 2008 Liu et al. J Chem Eng Data 57 (2012) Lichtfers (2000)

8 8 CAP pilot testing CO 2 absorber tests

9 9 Test rig CO 2 absorber

10 10 Systematic treatment of raw data from pilot plant tests min F = y y σ y constrained to f x, y, u = u u σ u 2

11 11 Automatized steady state detection Experiment 14 Experiment 21 Sample 1 Sample 1 Sample 2 Sample 2

12 12 Mass balances before data reconciliation CO 2 capture test NH 3 removal test Composition and flowrate of liquid streams are critical for closing the mass balances

13 13 Reconciled data for analysis and modelling Inlet gas Failure in the in the inlet gas flowrate sensor during the tests CO 2 capture test NH 3 removal test

14 14 Reconciled data for analysis and modelling Outlet gas CO 2 capture test NH 3 removal test

15 15 Reconciled data for analysis and modelling Inlet liquid CO 2 capture test NH 3 removal test

16 16 Reconciled data for analysis and modelling Outlet liquid Most uncertainties are in the measurement of the flowrate and composition of the outlet liquid stream CO 2 capture test NH 3 removal test

Current status of R&D in post combustion CO 2 capture

Current status of R&D in post combustion CO 2 capture Kaj Thomsen, Ph.D. Center for Energy Resources Engineering, CERE DTU Chemical Engineering Technical University of Denmark Outline Choice of solvent