technical evaluation of co compression and purification in ... · systems analysis and technology...

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Technical evaluation of CO2

compression and purification in CCS power plants

R. Castillo

Institute of Energy Research –

Systems Analysis and Technology Evaluation (IEF-STE)

Forschungszentrum

Jülich

4th

International Conference on Clean Coal Technologies CCT2009

Dresden, 20.05.2009

Institute of Energy Research

Systems Analysis and Technology Evaluation (IEF-STE) Slide 2 R. Castillo

1.

Introduction

2.

Methodological Approach

3.

Simple CO2

Compression

4.

CO2

Compression and Cryogenic Purification

5.

Conclusions

Presentation

Distribution



Carbon capture and storage (CCS) is a promising technology to reduce the contribution of CO2 emissions to global warming.

The energy required by the CO2 compression system represents an important burden to the total plant efficiency and is directly related to the level of CO2 impurities.

Objective:

To determine the effect of impurities on the CO2

compression process, as well as to identify the best operation conditions when a cryogenic purification is used.

1. Introduction



1.

Introduction

2.


3.

Simple CO2

Compression

4.

CO2


5.

Conclusions

Presentation

Distribution



Impure CO2

Captured Composition:•

Oxy-fuel: Lignite fired Lippendorf

power plant with ASU (No

air in-filtrations)•

IGCC: Solvent absorption process with Selexol•

Post-Combustion: Amine-based chemical absorption (99.9% purity)

2. Methodological Approach

Flue Gas Composition [% vol] Oxy-fuel Pre-combustion (IGCC) Component

Molar Mass

[kg/kmol] LP LP MP HP_1 HP_2

CO2 44 35.40 99.52 97.63 87.42 81.87 Ar 40 2.20 0.00 0.05 0.08 0.29 N2 28 0.20 0.00 0.00 7.75 0.02 H2 2 - 0.05 1.68 4.05 15.73

CH4 16 - 0.04 0.47 0.53 1.75 CO 28 - 0.00 0.05 0.07 0.25 SO2 64 0.60 - - - - O2 32 1.20 - - - -

H2O 18 60.40 0.39 0.12 0.10 0.09 Mass flow (kg/s) 371.1 44.5 21.2 47.7 16.9

Temperature (°C) 190.0 10.6 20.0 32.2 23.9 Pressure (bar) 1.0 1.5 11.0 14.1 20.6

Sources:

Oxy-fuel: Birkestad, H. 2002IGCC: Moore, J., 2007



CO2

Compression System:

•

Compressors: intercooled centrifugal compressors•

Pressure ratio: 5 (Max. per step)•

Polytrophic efficiency: 80%•

Cooling temperature: 20°C•

Pumps efficiency: 85%, mechanical: 98%•

Final compression pressure: 100 bar -120 bar•

Impure CO2

mixture: Dry composition•

Simulation software: Aspen Plus•

Thermodynamic properties: Peng-Robinson property method

2. Methodological Approach



1.

Introduction

2.


3.

Simple CO2

Compression

4.

CO2


5.

Conclusions

Presentation

Distribution



3. Simple CO2

Compression

T [°C] P [bar]

20

1

1

20

30

2

COMP1 COMP2PUMP1

20

58

3

32

120

4

20

1

30

BP

P [bar]

T [°C]

120P [bar]

1

30

58

120

20

liquid [bar] Vapor

liquid [bar]

Vapor

Pure CO2 Impure

CO2

1

2

3

4

1

2

3

4

T [°C]

Critical

Point

Critical

Point

The higher the BP pressure , the higher the compression work!!!

1 2 3

4



Impure CO2 (10% contaminant): Molar Mass and Bubbling Point Pressure at 20°C

41.2

42.4 42.442.8

44.0

46.0

39.8

43.6

75

94 9184 83

58

143

50

39

41

43

45

47

M_m

ix BP

M_m

ix BP

M_m

ix BP

M_m

ix BP

M_m

ix BP

M_m

ix BP

M_m

ix BP

M_m

ix BP

H2 CH4 N2 CO O2 Ar CO2 SO2

40

60

80

100

120

140

M [kg/kmol] BP@20°C [bar]

3. Simple CO2

Compression:Impure two-component mixtures

•

Evaluate the influence each individual gas contaminant: H2

, CH4

, N2

, CO, O2

, Ar

and SO2•

Mixtures with 5% and 10% of impurity

BP Pressure

[bar]Molar Mass

[kg/kmol]



3. Simple CO2


•

Effect on the Compression work (120 bar)Pure CO2

: 0.089 [kWh/kg]

Compression Work (120 bar) Relative Difference [%]

29

1315 15

12 10

-9

79 8

6 5

0

22

-5H2 CH4 N2 CO O2 Ar CO2 SO2

Impurity: 10% 5%

SO2



3. Simple CO2


•

Effect on the storage density (40°C, 100 bar)Pure CO2

: 564 [kg/m3]

Storage Density Relative Difference [%]

-51

-35-44 -43 -39 -38

35

0

-35

20

-20-29 -29 -24 -23

H2 CH4 N2 CO O2 Ar CO2 SO2

Impurity: 10% 5%

With

H2

O, Corrosive!!!



3. Simple CO2

Compression:Particular Oxy-fuel and IGCC mixtures

•

Dry impure CO2

: Mixture A1 (Oxy-fuel), Mixture A2 (IGCC)•

Compression from 1 bar to 120 barComponent [%vol]

Mixture CO2 Ar N2 H2 CH4 CO SO2 O2

Molar Mass

[kg/kmol]

BP Pressure

[bar]

Pure CO2 100.0 - - - - - - - 44 58 Mixture A1 89.3 5.7 0.3 - - - 1.6 3.1 43.7 82 Mixture A2 92.3 0.1 2.9 4.1 0.5 0.1 - - 41.7 100

Oxy-fuelIGCC

Storage Density [kg/m3](100 bar, 40°C)

564

383330

CO2

Oxy-fuel

mixture

IGCC mixture

Compression Work[kWh/kg_Mix]

0.0900.087

0.096 0.098

0.1070.106

BP 120

Compression Pressure [bar]

Oxy-fuel IGCC



1.

Introduction

2.


3.

Simple CO2

Compression

4.

CO2


5.

Conclusions

Presentation

Distribution



4. CO2


Simple CO2

compression disadvantages:•

Low liquid CO2

purity•

Low CO2

storage density (≈40% less than pure CO2

)•

Normal oscillations of the BP pressure, pump problems

1 3 4

5

6 7Cryogenic

Liquefaction Unit

Compression Unit

Pumping Unit

Separation Unit

Impure CO2 mixture(s)

Impure CO2(gas)

Compressed & Liquefied

CO2

Performance parameters:•

Separation ratio (How much impure CO2

is liquefied) [%]•

Liquid carbon dioxide purity [%vol]•

Specific compression work [kWh/kgCO2

]•

CO2

separation ratio (How much pure CO2

is recovered)

[%]

P4

T4

1 3

6

4

Separation parameters 5



4. CO2


Purification devices:•

Flash drum (isothermal, SR≥90%)•

Distillation column (12 stages, SR=90%, reflux ratio=2)

Final compression pressure:100 bar

20

1

P [bar]

T [°C]

Vapor

1

2

3

4P4

liquid [bar]

BubblingPoint Line

Dew Point Line

T4

DP

BP

-50°C ≤

T4 ≤

10°C

avoid

CO2 ice

(triple

point temp: -56°C)



Specific Compression Work [kWh/kg_liqCO2]Oxy-fuel Mixture: Flash Separation Process

0.100

0.105

0.110

0.115

0.120

0.125

10 20 30 40 50 60 70

Separator Pressure (P4) [bar]

-40°C

-30°C

-50°C

-10°C

0°C 10°C-20°C

Liquefied CO2 Purity [%]Oxy-fuel Mixture: Flash Separation Process

89

90

91

92

93

94

95

10 20 30 40 50 60 70


-40°C-30°C

-10°C

0°C10°C

-20°C

-50°C

4. CO2

Compression and Cryogenic PurificationOxy-fuel mixture –

Flash separation

SR=90%

SR=100%

SR=90%

Best operating

point

Best operating

point



Specific Compression Work [kWh/kg_liqCO2]Oxy-fuel Mixture: Distillation Process

0.105

0.115

0.125

0.135

0.145

0.155

10 20 30 40 50 60 70


-40°C-30°C

-50°C

-10°C 0°C 10°C-20°C

Liquefied CO2 Purity [%]Oxy-fuel Mixture: Distillation Process

93

94

95

96

97

98

99

10 20 30 40 50 60 70


-40°C

-30°C

-50°C

-10°C

0°C10°C

98.2% (max.)

-20°C

4. CO2

Compression and Cryogenic PurificationOxy-fuel mixture –

Distillation column

Max. purity

Max. purity

Best operating point


Separation ratio

(SR): 90%



4. CO2

Compression and Cryogenic PurificationIGCC mixture

3 4

5

6 7Cryogenic

Liquefaction Unit

Pumping Unit

SeparationUnit

Impure CO2

(gas)

Compressed & Liquefied

CO2

1A (LP)

1B (MP)

1C (HP_1)

1D (HP_2)

2

1st Compression Unit

2nd CompressionUnit

1.5 bar

11 bar

14.1 bar

20.6 bar 100 bar

From

Selexolprocess



4. CO2

Compression and Cryogenic PurificationBest cases

>50 000 mg/Nm3

Limit: ≤

200 mg/Nm3 (*)

>96% ok!

Presence

of H2 and N2

High CO2

purity

High purity

and SO2

content

Important presence ofAr and O2 (Oxy-fuel)

and H2 and N2 (IGCC)

(*) Source: Anhenden, M. 2008



4. CO2

Compression and Cryogenic PurificationOxy-fuel Process: Effect of air in-filtrations

Combustion Coal type hard coal (Kleinkopje) LHV dry [kJ/kg] 24991 Coal stream [kg/s] 48.5 Sulfur content [%] 0.64 Tcoal [°C] 15 Recirculation ratio [%] 66 - 67 Tadiabat [°C] 2120 TCOMB [°C] 1200 Lambda 1.15 O2 stoichiometric [kg/s] 94.84

O2 combustion [kg/s] 109.07 Tfluegas [°C] 350 Toxygen [°C] 80 Ash separation Furnace (slag) 40% E-Filter (Fly ash) 60% E-filter efficiency 99.50% Oxygen Composition [%vol] 99.5 98 95 Oxygen 0.995 0.980 0.950 Argon 0.005 0.020 0.038 Nitrogen 0.000 0.000 0.012

Composition

before

compression:



4. CO2

Compression and Cryogenic PurificationOxy-fuel Process: Effect of air in-filtrations

Oxygen Purity: 99.5 %

Using Flash Drum Using Distillation Column Air infiltration Air infiltration

NO 1% 3% NO 1% 3% T4 [°C] -50 -50 -50 -30 -20 -10 P4 [bar] 13.6 22.5 52.2 22 42 68 Flue gas mass flow [kg/s] 122.2 126.4 134.8 122.2 126.4 134.8 CO2 purity before Compression [%] 93.27 88.70 80.79 93.27 88.70 80.79 Impure CO2 recovery mass flow [kg/s] 109.9 113.7 121.3 109.9 113.7 121.3 Liquid CO2 purity [%] 97.89 95.85 89.49 99.29 98.23 89.90 Separation ratio [%] 90 90 90 90 90 90 CO2 separation ratio [%] 93.27 95.08 96.71 94.24 96.73 97.06 Specific compression work [kWh/kgCO2] 0.1063 0.1191 0.1378 0.1107 0.1266 0.1317 Total compression work [MW] 42.06 48.75 60.20 43.8 51.8 57.5 Plant efficiency reduction [% points] -3.48 -4.03 -4.98 -3.62 -4.28 -4.75 Storage density [kg/m3] 509 449 330 546 517 333



1.

Introduction

2.


3.

Simple CO2

Compression

4.

CO2


5.

Conclusions

Presentation

Distribution



5. Conclusions

Light contaminants such as H2, N2, CO, O2 and Ar strongly increase the compression work, and reduce the density of CO2 at storage conditions.

Although the presence of SO2 (heavy impurity) benefits the storage density and reduce the energetic compression requirements, in the presence of water this component is highly corrosive and must be removed.

The distillation column has two advantages over the flash drum: higher amounts of CO2 are recovered, with higher purity, but more energy is required

Compared with the compression of pure CO2 the Oxy-fuel mixture requires less energy (≈+30% for Oxy-fuel and +50% for IGCC-Selexol)

The presence of air infiltrations (1-3%) in Oxy-fuel power plants strongly affects the performance of the compression system (from -0.5% to -1.5% plant efficiency)

The more favorable operating separation-purification conditions using a flash drum are at low temperatures (between -50°C and -30°C).



¡Muchas

gracias señoras,señoritas

y señores!

Renzo Castillo:E-mail: [email protected]: +49 (0) 2461-6556

mailto:[email protected]



Renzo Castillo:E-mail: [email protected]: +49 (0) 2461-6556

mailto:[email protected]



4. CO2

Compression and Cryogenic PurificationIGCC mixture –

Flash drum

Liquefied CO2 Purity, X6_CO2 [%]IGCC-Mixture: Flash Separation Process

92

94

96

98

100

10 20 30 40 50 60 70 80 90 100 110

Separator Pressure P4 [bar]

-40°C

-30°C

-50°C

-10°C

0°C

10°C

-20°C

-40°C-30°C

-50°C

-10°C0°C

10°C

-20°C

SR=90%

-50°C ≤T4≤10°C

Specific Compression Work, WC_m6 [kWh/kg]IGCC-Mixture: Flash Separation Process

0.05

0.06

0.07

0.08

0.09

10 20 30 40 50 60 70 80 90 100 110


-40°C-30°C

-50°C

-10°C

0°C

10°C

-20°C -10°C0°C

10°C

-40°C

-30°C

-50°C

-20°CSR=90%

SR=90%





Liquefied CO2 Purity, X6_CO2 [%]IGCC-Mixture: Distillation Process

97.5

98.0

98.5

99.0

99.5

100.0

10 20 30 40 50 60 70


-40°C -30°C-50°C

-10°C

0°C

-20°C

10°C

X6_CO2, max

-50°C ≤T4≤10°C

Specific Compression Work, WC_m6 [kWh/kg]IGCC-Mixture: Distillation Process

0.055

0.065

0.075

0.085

0.095

10 20 30 40 50 60 70


-40°C

-30°C

-50°C

-10°C 0°C10°C

-20°C

-50°C =T4 =10°C

X6_CO2 , max

4. CO2

Compression and Cryogenic PurificationIGCC mixture –

Distillation column

Best operating pointBest operating point



4. CO2

Compression and Cryogenic PurificationOxy-fuel mixture: Effect of air infiltrations

Specific Compression Work [kWh/kg](No air-infiltrations)

0.11

0.12

0.13

0.14

0.15

-50 -40 -30 -20 -10 0

TSEP = T4 [°C]

99.5% 98% 95%

Specific Compression Work [kWh/kg](1% air-infiltrations)

0.11

0.12

0.13

0.14

0.15

-50 -40 -30 -20 -10 0

TSEP = T4 [°C]

99.5% 98% 95%

Specific Compression Work [kWh/kg](3% air-infiltrations)

0.11

0.12

0.13

0.14

0.15

-50 -40 -30 -20 -10 0TSEP = T4 [°C]

99.5% 98% 95%

Flash drum:Specific Compression work

Pure CO2

: 0.089 [kWh/kgCO2

]•

Oxygen purity:99.5%, 98% and 95%

•

Air infiltration: 1% and 3%•

SR = 90%



4. CO2

Compression and Cryogenic PurificationOxy-fuel process: Effect of air infiltrations

Flash drum:CO2

purity [%vol]•

Oxygen purity:99.5%, 98% and 95%

•

Air infiltration: 1% and 3%•

SR = 90%

CO2 Purity [% vol](No air-infiltrations)

0.80

0.850.90

0.95

1.00

-50 -40 -30 -20 -10 0

TSEP = T4 [°C]

99.5% 98% 95%

CO2 Purity [% vol](1% air-infiltrations)

0.80

0.85

0.90

0.95

1.00

-50 -40 -30 -20 -10 0

TSEP = T4 [°C]

99.5% 98% 95%

CO2 Purity [% vol](3% air-infiltrations)

0.80

0.85

0.90

0.95

1.00

-50 -40 -30 -20 -10 0

TSEP = T4 [°C]

99.5% 98% 95%



4. CO2

Compression and Cryogenic PurificationIGCC mixture

Source: Ciferno, NETL 2007

Captured CO2

streams



4. CO2

Compression and Cryogenic PurificationRefrigeration: Energy Consumption

But…

in the

presence

of NO2, SO2 will be

converted

to SO3 during

compression

(Air Products

Experiment)

Refrigeration - Energy Consumption1/COP [kWel/kWth]

y = 4E-05x2 - 0.0054x + 0.1507R2 = 0.9978

0.15

0.25

0.35

0.45

0.55

-50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0

Tsep [°C]

technical evaluation of co compression and purification in ... · systems analysis and technology...

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