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Thermodynamics of Phase Change Solvents

Waseem Arshad, Muhammad; Thomsen, Kaj; von Solms, Nicolas; Svendsen, Hallvard Fjøsne

Publication date:2013

Document VersionPublisher's PDF, also known as Version of record

Link back to DTU Orbit

Citation (APA):Waseem Arshad, M. (Author), Thomsen, K. (Author), von Solms, N. (Author), & Svendsen, H. F. (Author).(2013). Thermodynamics of Phase Change Solvents. Sound/Visual production (digital)

CCS Conference 2013: 28‐29 May, 2013Antwerp, Belgium

Muhammad Waseem Arshad

Supervisors: Assoc. Prof. Kaj Thomsen (DTU) Assoc. Prof. Nicolas von Solms (DTU)Prof. Hallvard Fjøsne Svendsen (NTNU)

Thermodynamics of Phase Change Solvents

Outline

2

• Introduction• Experimental Work Freezing Point Depression  Heat of Absorption  Vapor liquid equillibrium

• Thermodynamic Modeling DEEA‐CO2‐H2O 

• Main Conclusions• Future work

Introduction

2‐(diethylamino)ethanol   (DEEA)

• Low heat of reaction (bicarbonate)• Low heat requirement for reversion • High loading capacity• Low reaction rate

3‐(methylamino)propylamine  (MAPA)

• Fast reaction rate• High heat of reaction (carbamate)• High heat requirement for reversion

3

Introduction

CO2 lean phase

4

CO2 rich phase

Phase change solventDEEA‐MAPA‐CO2‐H2O system give liquid‐liquid split with lower phase rich in CO2 and upper phase lean in CO2

‐ Phase change solvents has potetial for:• Low ciculation rate in the desorber

• Smaller size of desorber (low capital cost)

• Improved energy efficiency

Introduction

5

Lean Phase

Rich Phase

Decanter

Mixer

6

Freezing Point Depression 

• Measurement of freezing point is considered the most accurate method to determine water activity

– Water activity is a key parameter for the amount of water evaporated in the desorber

– Low water activity means less evaporation of water in the desorber and low energy consumption during solvent regeneration

– Water activity is only a weak function of temperature– Water activity measured at low temperature is not very different from water activity at absorber and stripper temperatures

– Water activity is very useful for thermodynamic modelling

Experimental: Freezing Point Depression 

7

A, Thermostatic bath with ethanol  B, Cooling jacket C, Sample glass with magnetic

stirrer D, Rubber stopper with sample

glass lid E, Device for manual stirring F, Controlled temperature ethanolbath with magnetic stirrer 

G, Pt100 Thermometer H, Data acquisition unit 

Fosbøl, P. L.; Pedersen, M. G.; Thomsen, K. J. Chem. Eng. Data 2011, 56, 995‐1000.

Experimental: Freezing Point Depression 

8

Measured Freezing Point

Heat of Crystallisation

Crystallisation

Fosbøl, P. L.; Pedersen, M. G.; Thomsen, K. J. Chem. Eng. Data 2011, 56, 995‐1000.

9

DEEA‐MAPA‐H2ODEEA‐H2O and MAPA‐H2O

Results: Freezing Point Depression 

Arshad, M. W.; Fosbøl, P. L.; von Solms, N.; Thomsen, K. J. Chem. Eng. Data 2013, published online.

10

DEEA‐CO2‐H2O MAPA‐CO2‐H2O

Results: Freezing Point Depression 

Arshad, M. W.; Fosbøl, P. L.; von Solms, N.; Thomsen, K. J. Chem. Eng. Data 2013, published online.

1, 2L jacketed reactor2a & 2b, CO2 storage cylinders3, CO2 mass flow controller4, Amine solution feed bottle5, Vaccuum pump

Calorimeter Model CPA‐122Chemisens AB, Sweden

11Kim, I.; Svendsen. H. F. Ind. Eng. Chem. Res. 2007, 46, 5803‐5809

4

2b

1

CO2

2a

Control DeviceVRC200

FCO2

PP

P

P

P

5

T

Control Device

Thermostat

WP TN

T TP

n

3

To air

Vacuum

Experimental: Heat of Absorption and VLE of CO2

• Moles of CO2 (Peng‐Robinson  EOS)• Power curve (Integration)• Amine concentration (known)

12

Experimental: Heat of Absorption and VLE of CO2

Tested Concentrations

• 5M DEEA

• 2M MAPA

• 1M MAPA

• 5M DEEA + 2M MAPA  (phase split)

• 5M DEEA + 1M MAPA  (phase split)

Temperature = 40 oC (absorption), 80 oC and 120 oC (desorption)Total Pressure = ~6 bar

13

Sample Results: Heat of Absorption

Overall comparison of all systems at Absorption & Desorption  conditions

14

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

∆H

abs

(kJ/

mol

CO

2)

Loading (mol CO2/ mol amine)

40oC

5M DEEA2M MAPA1M MAPA5M DEEA + 2M MAPA5M DEEA + 1M MAPA30% MEA (0.5 CO2 Loading)

0

50

100

150

200

250

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Loading (mol CO2/ mol amine)

120oC5M DEEA2M MAPA1M MAPA5M DEEA + 2M MAPA5M DEEA + 1M MAPA30% MEA (0.5 CO2 Loading)

Arshad, M. W.; Fosbøl, P. L.; von Solms, N.; Svendsen, H. F.; Thomsen, K. Submitted to J. Chem. Eng. Data.

VLE of CO2 in 5M DEEA 

15

0

200

400

600

800

1000

1200

0 0.2 0.4 0.6 0.8 1 1.2

Ptot

al(k

Pa)

CO2 Loading (mol CO2/ mol DEEA)

5M DEEA 40 oC - This work

80 oC - This work

120 oC - This work

80 oC - iCap D1.3.2

100 oC - iCap D1.3.2

120 oC - iCap D1.3.2

Blue Data from Calorimeter  ‐ This workRed Data from Equilibrium Cell – iCap D1.3.2

Sample Results: Vapor‐Liquid Equilibrium of CO2

Thermodynamic Modeling

16

• Amine‐CO2‐H2O systems are electrolyte systems

• Extended UNIQUAC, an electrolyte thermodynamic model will be used to model the phase change solvents system

• The systems to be modeled are: DEEA‐CO2‐H2O MAPA‐CO2‐H2O DEEA‐MAPA‐CO2‐H2O (phase split)

Extended UNIQUAC

17

• Extended UNIQUAC = Original UNIQUAC + Extended Debye‐Hückle

• Liquid phase activity coefficients are calculated with the UNIQAC equation

• Vapor phase fugacity coefficients are calculated with SRK EoS

Combinatorail Residual Extended Debye-Hückle

E E E EG G G G

RT RT RT RT

UNIQUAC entropic termr = volume parameterq = surface area parameter

Electrostatic interaction

UNIQUAC enthalpic termBinary interaction energy parameter

0 298.15Tij ij iju u u T

Modeling: DEEA‐CO2‐H2O

18

Physical equilibria:

Chemical equilibria:

Vapor Pressure of DEEA

19

0

0.5

1

1.5

2

2.5

0 50 100 150 200 250

Vapo

r Pressure/ bar

T/ oC

Extended UNIQUAC

Kapteina et al., 2005

iCap D1.3.2, 2011

Klepacova et al., 2011

Steele et al., 2002

20

‐30

‐25

‐20

‐15

‐10

‐5

0

0 2 4 6 8 10 12

Freezing

 Point/ o C

DEEA/ mol per kg water

Extended UNIQUAC

This work

Freezing Point Depression of DEEA

21

Excess Molar Enthalpy of DEEA

‐3000

‐2500

‐2000

‐1500

‐1000

‐500

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

HE(J/ mol)

XDEEA (mol fraction)

Mathonat et al., 1997

Extended UNIQUAC

22

VLE of CO2 in 5M DEEA

0

1

2

3

4

5

6

7

8

0 2 4 6 8 10 12 14 16

PCO2/ ba

r

CO2 / mol per kg water

Extended UNIQUAC

5M DEEA ‐ 40oC, This work

5M DEEA ‐ 120oC, This work

23

Heat of Absorption of CO2 in 5M DEEA

‐70

‐60

‐50

‐40

‐30

‐20

‐10

00 2 4 6 8 10 12 14 16

∆Hab

s(kJ/ m

ol CO

2)

CO2 / mol per kg water

Extended UNIQUAC

5M DEEA ‐ 40oC, This Work

Main Conclusions• Freezing point depressions were measured in CO2 loaded and unloaded systems Unloaded systems: DEEA‐H2O, MAPA‐H2O and DEEA‐MAPA‐H2O Loaded systems: DEEA‐CO2‐H2O and MAPA‐CO2‐H2O

• Heat of absorption and VLE of CO2 data were measured at 40, 80 and 120oC for the systems: 5M DEEA  and  2M & 1M MAPA 5M DEEA + 2M MAPA  (phase split) 5M DEEA + 1M MAPA  (phase split)

• Model parameters were determined for the DEEA‐CO2‐H2Osystem

24

Future Work

• Improving the model parameters for DEEA‐CO2‐H2Osystem

• Modeling the MAPA‐CO2‐H2O and DEEA‐MAPA‐CO2‐H2O systems

25

Acknowledgement

• This project is fully funded by European Commissionunder the 7th Framework Program (Grant no.241393) through iCap project

26

Thank You!