using fundamental advanced thermodynamics to model co ... cap/4-4 dtu 09-09-30 sec.pdf · using...

Using fundamental advanced thermodynamics to model CO2 capture using aqueous ammonia30/09/200930/09/2009

Victor Darde Kaj Thomsen Willy van Well Erling HVictor Darde, Kaj Thomsen, Willy van Well, Erling H Stenby

12th ti f th i t ti l t b ti t t k12th meeting of the international post-combustion capture network

Regina, Canada

1

OutlineOutline

Description of the processDescription of the thermodynamic model

SpeciationSpeciationVLESLEEnthalpy change

Description of the resultsEquilibriumEquilibriumHeat requirement

Future work

2

CO2 capture using aqueous Process Model Results Future work

ammonia: introductionPost combustion process: use of MEAPost combustion process: use of MEA

Degradation of solvent and corrosionHigh energy consumption

Search for new alternativesSearch for new alternativesPost combustion processProcess can be found in 2 variants:

Absorption at ambient temperaturep pAbsorption at low temperature (chilled ammonia process), patented process (2006), developped by Alstom

Few publications and resultsSimilarities with MEA process but:Similarities with MEA process but:

Low temperature of absorption to prevent ammonia vaporizationNo degradation or corrosion issuesHigh pressure of the pure CO2 streamDecrease of the heat consumptionDecrease of the heat consumption

3

The thermodynamic model

Process Model Results Future work

The thermodynamic model

Need for a fundamental thermodynamic model to evaluateNeed for a fundamental thermodynamic model to evaluate the process

Original model: Thomsen and Rasmussen (1999) ( “ModelingOriginal model: Thomsen and Rasmussen (1999) ( Modeling of Vapor-liquid-solid equilibrium in gas-aqueous electrolyte systems”, Chemical Engineering Science 54(1999)1787-1802)

Valid for CO2-NH3-H2O mixtures2 3 2

Use of extended UNIQUACUp to 110°CAbout 2000 experimental data points on this system (Binary VLE, Ternary bout 000 e pe e ta data po ts o t s syste ( a y , e a yVLE, SLE, enthalpy…)

4

SpeciationSpeciation VLE SLE Enthalpy


The following reactions are considered:

Vapor-liquid equilibriumg

NH3 (aq)+ H+ ⇔ NH4+

CO2 (aq) + H2O (l) ⇔ HCO3- + H+

HCO3- ⇔ CO3

2- + H+

NH3 (aq) + HCO3- ⇔ NH2COO- + H2O (l)

The distribution of species in the liquid phase (speciation) is calculated with Extended UNIQUAC Gas phase components:

CO2 (g) ⇔ CO2 (aq)NH3 (g) ⇔ NH3 (aq)

O ( ) O ( )H2O (g) ⇔ H2O (l)

Chemical potentials calculated:SRK for the gas phase

Extended UNIQUAC for the liquid phase

5

Solid-liquid equilibrium Speciation VLE SLE Enthalpy


The following solids are considered

Enthalpy changeThe following solids are considered

NH2COONH4 Ammonium carbamateNH4HCO3 Ammonium bicarbonate(NH4)2CO3·H2O Ammonium carbonate(NH4)2CO3·2NH4HCO3 SesquicarbonateIce Solid water

SLE is handled by Extended UNIQUAC

A large amount of heat is developed when CO2 is dissolved in aqueous ammonia

Heat of reaction from speciation reactionsHeat of reaction from speciation reactionsExcess enthalpy of the ionic solution

Both terms are calculated with the Extended UNIQUAC model

6

Upgrading of the thermodynamic


model: Description of the workUpgrading of the model:pg g

Temperature correlation for the Henry constants for NH3 and CO2Calculation of the residual enthalpy of the gas phase with SRK

New data added: VLE at higher temperatureVLE at higher temperatureEnthalpy data from Rumpf B and Maurer G: partial evaporation of CO2-NH3-H2O mixturesSpeciation data from Lichtfers et al. (2000)Heat capacity dataHeat capacity data

All together: 4500 data points to refit the parameters, but some should not be trusted

3800 data selectedParameters

Refitting of 60 parametersSeveral optimization routinesCh i f th i ht f th d tChoice of the weight of the data

New set of parameters7

Binary NH3-H2O at high temperature and m(NH )


and m(NH3)Original Parameters New Parameters

Guillevic et al. (1985)70

80T=129.95T=179.95

Guillevic et al. (1985)70

80T=129.95T=179.95

30

40

50

60

Pres

sure

(Bar

)

30

40

50

60

Pres

sure

(Bar

)

0

10

20

0 20 40 60 80 100 120 140

P

0

10

20

0 20 40 60 80 100 120 140

P

Rizvi et al. (1985)

140

160

180T=126°CT=139°C

T=149°CT=179°C

0 20 40 60 80 100 120 140

m(NH3)m(NH3)Rizvi et al. (1985)

140

160

180

200

T=126°C

T=139°C

T=149°CT=179°C

132°C

60

80

100

120Pr

essu

re (B

ar)

T 179 C132°C

60

80

100

120

Pres

sure

(Bar

) 132°C

0

20

40

0 50 100 150 200 250 300 350 400 450

m(NH3)

0

20

40

0 50 100 150 200 250 300 350 400 450

m(NH3)

8

Ternary data at 120°C


Ternary data at 120 C(NH ) 0 7 (NH ) 3 8 (NH ) 5 8 (NH ) 11 8

40

50

)

Göppert et al. (1988)Müller et al. (1988)Extended UNIQUAC

m(NH3)=0.7 m(NH3)=3.8 m(NH3)=5.8 m(NH3)=11.8

30

sure

(Bar

)

m(NH3)=12.4m(NH3)=20.4

m(NH )=25 7

10

20

Pres

s m(NH3)=25.7

m(NH3)=8.1

0

10

0 2 4 6 8 10 120 2 4 6 8 10 12CO2 mol kg-1

9

Ternary 180°C


Ternary 180 COriginal parameters New parametersOriginal parameters

Müller et al. (1988)

100

120UNIQUAC calculationT=180°C, m(NH3)=2.52T=180°C, m(NH3)=6.85

Müller et al. (1988)80

90

UNIQUAC calculationT=180°C, m(NH3)=2.52

New parameters

60

80

100

re (B

ar)

T=180°C, m(NH3)=12.6

50

60

70

ure

(Bar

)

T=180°C, m(NH3)=6.85T=180°C, m(NH3)=12.6

20

40

60

Pres

sur

20

30

40

Pres

su

0

20

0 0,5 1 1,5 2 2,5 3 3,5 4m(CO2)

0

10

0 0,5 1 1,5 2 2,5 3 3,5 4m(CO2)

10

0 6

0,7

0,8

ol N

H3)

Extended UNIQUACJänecke (1929)Terres & Weiser (1921)Terres & Behrens (1928)Guyer & Piechowicz (1944)SLE results


0,4

0,5

0,6

g (m

ol C

O2/m

o y ( )

(NH4)2CO3•H2O

NH4HCO3

(NH4)2CO3•2NH4HCO

SLE results

0,1

0,2

0,3

CO

2 loa

ding

NH2COONH4

(NH4)2CO3 2NH4HCOUse of Jänecke data only (1929)

for parameter estimationNew parameters

0-6 14 34 54 74

Temperature, °C

N 2COON 4

0 7

0,8Extended UNIQUACJänecke (1929)

0,5

0,6

0,7

adin

g

Terres & Weiser (1921)Terres & Behrens (1928)Guyer & Piechowicz (1944)

NH4HCO3

0,2

0,3

0,4

CO

2 loa (NH4)2CO3•H2O

(NH4)2CO3•2NH4HCO3

Original parameters

0

0,1

-4 6 16 26 36 46 56 66 76 86Temperature, °C

NH2COONH4

11

Speciation data (Lichtfers, 2000)T=80°C, m(NH3)=6.1

6

7NH3(aq), Extended UNIQUACNH4+, Extended UNIQUACNH2COO-, Extended UNIQUACNH3, Lichtfers, 2000NH4 Li htf 2000 3

3,5

4

HCO3-, Extended UNIQUACCO3--, Extended UNIQUACCO2(aq), Extended UNIQUACCO2, Lichtfers, 2000

3

4

5NH4+, Lichtfers, 2000NH2COO-, Lichtfers, 2000

2

2,5

3CO3--, Lichtfers, 2000HCO3-, Lichtfers, 2000

1

2

3

0,5

1

1,5

00 2 4

m CO2 mol/kg

0

,

0 2 4

m CO2 mol/kg

12

Modelling: Conclusion


Modelling: Conclusion

Upgrade of the modelExtension of the validity of the temperature rangeU f ki d f i t l d t f tUse of new kind of experimental data for parameter estimationModel can accurately describe the thermodynamicModel can accurately describe the thermodynamic properties of NH3-CO2-H2O

13

Absorption at 10°C for NH =10wt%

Equilibrium Heat requirementProcess Model Results Future work

NH4HCO3

5

6

7

NH4HCO3

0,080,090,1

NH3(aq)NH4+CO3--Absorption at 10 C for NH3=10wt%

3

4

5

umbe

r of m

ole

0,040,050,060,07

Mol

e fr

actio

n HCO3-NH2COO-

0

1

2nu

00,010,020,03M

0,25

0,

31

0,37

0,

43

0,49

0,

55

0,61

0,

67

0,73

0,

79

0,85

0,

91

0,97

CO2 loading (mol CO2/mol NH3)

0,25

0,

31

0,37

0,

43

0,49

0,

55

0,61

0,

67

0,73

0,

79

0,85

0,

91

0,97


0,120Formation of ammonium bicarbonate

0,080

0,100

,

e (B

ar)

TotalH2ONH3CO2

High pressure of NH3 at low

0,020

0,040

0,060

Pres

sure

High pressure of NH3 at low loading

0,000

0,25

0,

31

0,37

0,

43

0,49

0,

55

0,61

0,

67

0,73

0,

79

0,85

0,

91

0,97


14

Desorption at 110°C for Equilibrium Heat requirement

Process Model Results Future work100,0

TotalH2ONH3CO2

NH3=10wt%10,0

Pres

sure

(Bar

)

1,0

P

0,9

1,0H2ONH3

0,1

0,25

0,

28

0,31

0,

34

0,37

0,

40

0,43

0,

46

0,49

0,

52

0,55

0,

58

0,61

0,

64

0,67

0,

70

0,73

0,

76

CO2 loading

High CO2 pressure for high0,6

0,7

0,8

,

actio

n

NH3CO2

High CO2 pressure for high loading

0,2

0,3

0,4

0,5M

ole

fra

0,0

0,1

0,25

0,

28

0,31

0,

34

0,37

0,

40

0,43

0,

46

0,49

0,

52

0,55

0,

58

0,61

0,

64

0,67

0,

70

0,73

0,

76

CO2 loading

15

Heat requirement in the desorber


Heat requirement in the desorber• Reference Configuration

Ammonia initial mass

fraction

T CO2 Lean stream

T CO2 Rich stream

T Water and Ammonia

from condenser

Lean CO2loading

Rich CO2loading

12% 110°C 100°C 25°C 0 33 0 67

• Influence of 5 variables on the enthalpy balance

2400

2500

g

12% 110°C 100°C 25°C 0.33 0.67

2100

2200

2300

2400

uire

men

t (kJ

/kg

capt

ured

)

Heat requirement desorber MEA: 3700kJ/kg CO2captured (CASTOR project)

significant decrease of

1800

1900

2000

0,28

0,26

0,24

0,220,20,18

0,16

0,14

0,120,10,08

Ener

gy R

eqC

O2

c significant decrease of the heat consumption

0,0,0,0,0,0,0,0,0,Ammonia initial mass fraction

16

Heat requirement in the heat Equilibrium Heat requirement


CO2-rich stream CO2-rich stream90°C

exchangerEnthalpy necessary:650 kJ for 1kg H2O

Heat exchanger

10°C 90 C650 kJ for 1kg H2O

CO2-lean stream110°C

CO2-lean stream30°C Enthalpy transferred:

480 kJ for 1kg H2O

NH3=28wt%Reference configuration ΔTh t h = 20°CΔTheat exchanger 20 C

A maximum of 74% of the CO2-rich stream can be heated, because of the presence of solid psignificant need for extra heat (645kJ/kg CO2 captured)

17

Heat requirement in the heat Equilibrium Heat requirement


800

900

r (kJ

)

Enthalpy necessary to heat the CO2-rich stream for ammonia 28wt%Enthalpy transfered from the CO2-lean stream for ammonia 28wt%Enthalpy necessary to heat the CO2-rich stream for ammonia 10wt%Enthalpy transfered from the CO2-lean stream for ammonia 10wt%

exchanger600

700

er k

g w

ater

py

300

400

500

f sol

vent

pe

100

200

300

Enth

alpy

of

0

100

0 20 40 60 80 100 120T (°C)

E

• Need for additional energy to heat the CO2-rich stream and dissolve the solid phase for a high NH3 concentrationP ibilit t l lit h t il bl t th l t

T ( C)

• Possibility to use low quality heat available at the power plant• Limited in the case of a low NH3 concentration18

Heat requirement: Conclusion


Heat requirement: Conclusion

Heat requirement desorber chilled ammonia lower thanHeat requirement desorber chilled ammonia lower than 2000kJ/kg CO2 captured Significant reduction of the heat consumption in the desorberOptimization of the configuration of the process to minimizeOptimization of the configuration of the process to minimize the heat consumptionAdditional energy savings during compression But:But:

Additional heat requirement to heat the CO2-rich streamCooling duty for the chilling of the flue gas and solventHeat requirement to recover the vaporized ammonia

19

Future work


Future work

Thermodynamic model by itself is not sufficient to perform aThermodynamic model by itself is not sufficient to perform a thorough evaluation of the process:

Implementation on the thermodynamic model on ASPENTest of different configurationsTest of different configurationsOptimization of the capture process

Study of the integration of the process in the power plant technologytechnologyExperimental measurement of the kinetic rate of absorption of carbon dioxide by ammonia solvent:

D i d f t i f tt d ll lDesign and manufacturing of a wetted wall columnFirst tests performed

20

Thank you for your attention

[email protected]

21

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