Techno-Economic Study of CO2 Capture from a Cement Plant

Dursun Can Ozcan, Hyungwoong Ahn, Stefano Brandanis.brandani@ed.ac.uk

University of Edinburgh, Institute for Materials and Processes

Górazdze Cement SA (HeidelbergCement)

Outline

2

1. Background2. Detailed Base Cement Plant Simulation3. Integration of Selected CO2 Capture Technologies with the Base

Cement Plant:• Ca-looping Process • Ca-Cu Looping Process • Indirect Calcination • Amine Process • Membrane Process

4. The Economic Evaluation of the CO2 Capture Processes5. Conclusions

Ozcan D.C., Ahn H. and Brandani S. Process Integration of a Ca-Looping Carbon Capture Processin a Cement Plant. International Journal of Greenhouse Gas Control, 2013, 19, 530–540. DOI: 10.1016/j.ijggc.2013.10.009

1. Background1. Background

3

• Global CO2 emissions hit a new record of 34.5 Gt in 2012 → 40.2 Gt by 2030.1,2

• CO2 concentration has reached 400 ppm in 2013, representing an increase of 24% from 1958.3

• Fossil fuels will remain as dominant energy provider for combustion systems unless clearer alternative energy systems are developed.4

• The UK aims for at least 80% reduction in its CO2 emissions relative to 1990 levels by 2050.5

1 Olivier et al., PBL 2013 Report. 2 IEA, World Energy Outlook 2009.3 Dlugokencky and Tans, NOAA/ESRL, 2014. 4 IEA, World Energy Outlook 2012. 5 Climate Change Act, 2008.

Carbon Capture and Storage (CCS)Carbon Capture and Storage (CCS)

4

A promising and an emerging way of reducing CO2 emissions from the main contributors: fossil-fuelled power stations and industrial processes Up to 19% reductions in CO2 emissions by 2050 can be achieved 1

CO2 capture accounts for 65-85% of the overall cost associated with CCS 2

It is important to develop efficient and cost-effective carbon capture technologies

1 IEA, Energy Technology Perspectives, 2010. 2 Rao and Rubin, Environ. Sci. Technol., 4467, 2002.

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Motivation and ObjectivesMotivation and Objectives

• The demand of cement has reached 3.78 billion tons in 2012.1

• The cement industry is the second largest anthropogenic greenhouse source.2

• It is important to extend CO2 capture to cover cement industry to reach the CO2

capture target stated in the Climate Change Act.3

• In this study, the primary aims are:o Evaluate the techno-economic performance of the Ca-looping process for

CO2 capture from cement plantso Investigate an advanced configuration of the Ca-looping process where the

energy intensive ASU is replaced with a CLCo Assess various alternative carbon capture technologies including oxy-

combustion, amine process, indirect calcination and membrane processes

1 CW Group, Global Cement Volume Forecast Report, 2012. 2 IEA, Carbon Emission Reductions up to 2050, 2009.3 Climate change act, 2008.

2. CO2 Emissions from Cement Industry2. CO2 Emissions from Cement Industry

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• 60% of the total emission accounts for calcination of limestone in raw meal• A more efficient thermal management has potentially reduced CO2 emissions1

• Carbon capture technology is essential to reduce CO2 emission up to 90%

1 Hasanbeigi et al., Renewable and Sustainable Energy Reviews, 6220, 2012.

Schematic diagram of a cement plant

o The enthalpy of formation of 1kg of a Portland cement clinker is around +1757 kJ/kg1,2

Chemical ReactionsChemical Reactions

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1 Cement Chemistry, H F W Taylor, 2nd ed. 1997. 2 Mojumdar et. al. Ceramics – Silikaty, 110, 2002.

Reaction ΔH (kJ) For 1kg of

CaCO3 (Calcite) CaO + CO2(g) +1782 CaCO3

AS4H (pyrophyllite) α-Al2O3 + 4SiO2(quartz) + H2O(g) +224 AS4H

AS2H2 (kaolinite) α-Al2O3 + 2SiO2(quartz) + 2H2O(g) +538 AS2H2

2FeO⋅OH (goethite) α-Fe2O3 + H2O(g) +254 FeO⋅OH

2CaO + SiO2 (quartz) ß-C2S -734 C2S

3CaO + SiO2 (quartz) C3S -495 C3S

3CaO + α-Al2O3 C3A -27 C3A

6CaO + 2 α-Al2O3 + α-Fe2O3 C6A2F -157 C6A2F

4CaO + α-Al2O3 + α-Fe2O3 C4AF -105 C4AF

Phase Change in Cement PlantPhase Change in Cement Plant

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Pre-heaters • 30% sulphur reacts with oxygen• Partial CaCO3 calcination• Partial clay minerals

decomposition

Pre-calciner• CaCO3 calcination (>90%) and

clay mineral decomposition completed.

• Partial conversion of CaO to C2S.

Kiln• C2S to C3S conversion. C3A and

C4AF formed. • Aluminate and Ferrite melting.

Preheaters out

Pre-Calciner Kiln

Cement Chemistry, H F W Taylor, 2nd ed. 1997.

Mass and Energy BalancesMass and Energy Balances

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• The simulated clinker compositions are in good agreement with those estimated by the Bogue equation

• The CO2 generation intensity is around 0.8 ton CO2/ton clinker that is within the range of 0.65 – 0.92 ton CO2/ton cement1

• The required thermal energy for unit clinker production is estimated to be 3.13 MJth/kg clinker in an agreement with reported values2 (2.9 – 3.4 MJth/ton clinker)

Composition of raw meal feed Clinker composition

1 IEA, Tracking Industrial Energy Efficiency and CO2 emissions, 2007.2 WBCSD, Cement Industry and CO2 Performance, 2009.

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• Ca-looping agent (CaO) circulates between two reactors: CaO + CO2 ↔ CaCO3 (ΔH923 K = − 171 kJ/mol)* Carbonator: CO2 from the exothermic carbonation reaction at 600°C - 750°C * Calciner: CaCO3 is regenerated to CaO by endothermic calcination above 870°C

• Advantages: cheap CaO sorbent; relatively small energy penalty; mature CFB systems, smaller ASU; purge for cement manufacture

• Challenges: Sintering (loss of reactive surface area), sulphation and attrition

Charitos et al., Powder Technology, 117, 2010.

La Perada, Spain (1.7 MW pilot plant, www.caoling.eu)

3. Calcium Looping Process3. Calcium Looping Process

Carbonator ModelCarbonator Model

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Two mathematical models for carbonator have been compared in the study;• The simple model (all active fraction of CaO reacts with CO2)• The rigorous model1:

* CFB model operates in the fast fluidization regime* Particle distribution part has been applied from K-L model; lower dense region and upper lean region* The CO2 concentration at the exit has been estimated from the gaseous material balance by considering the first order kinetic law of carbonation degree

The carbonator model was implemented fully into UniSim via a component object model (COM) interface

The effect of sulfidation was considered by adjusting the k and Xr constants corresponding to sulfidation level of Piaseck limestone2 (valid up to 1% sulfidation)

1 Romano, M.C. Chem. Eng. Sci. 257, 2012. 2 Grasa et al. Ind. Eng. Chem. Res., 1630, 2008.

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Selection of an Optimal Feed StreamSelection of an Optimal Feed Stream

0

10

20

30

40

CO

2co

ncen

trat

ion

(m

ole%

)1st Preheater 2nd Preheater 3rd Preheater 4th Preheater Precalciner KilnRaw mill

0

200400

600

800

10001200

1400

1600

Tem

pera

ture

[C]

Raw Mill 1st Preheater 2nd Preheater 3rd Preheater 4th Preheater Pre-Calciner Kiln Cooler

Gas Flow

Solid Flow

Relatively low (~22 vol%)

Higher CO2concentration(~35 vol%)

Flue gas needs to be heated up to 650°C.

Flue gas temperature is around 650°C no preheating is required.

• The flue gas temperature and CO2 mole fraction varies over the cement process

Process IntegrationProcess Integration

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1) The flue gas from 3rd Preheater is diverted to the carbonator.2) CO2 depleted flue gas from the carbonator is routed to the 2nd Preheater for the

raw material preheating. 3) Part of excess air from the cooler is used for additional raw material heating.4) Purge from the carbon capture calciner is sent to the kiln.

Results – Carbonator ModelResults – Carbonator Model

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1

2

3

4

5

6

0 1 2 3 4 5 6

F R/F

CO

2

F0/FCO2

Rigorous model (w/ S)Rigorous model (w/o S)Simple model

• F0 = flow of make-up CaCO3 ; FCO2 = flow of CO2 in the carbonator gas inlet• Range of F0/FCO2 ratios have been examined

Lower limit is set as 0.20 → The heat demand in raw mill cannot be metUpper limit is determined as 5.80 → No calcite in the raw materials

0

10

20

30

40

50

60

70

80

90

100

0

2

4

6

8

10

12

0 1 2 3 4 5

CO

2 recovery in the carbonator [%]

Incr

emen

tal e

nerg

y con

sum

ptio

n pe

r CO

2av

oide

d [G

J th/t

on C

O2 a

void

ed]

F0/FCO2

Energy Consumption without Heat Recovery

Energy Consumption with Heat Recovery

CO₂ recovery in the carbonator

Results – EfficienciesResults – Efficiencies

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• Either 90% CO2 recovery in the carbonator or 90% overall avoidance rate.• The net energy consumption per unit clinker production is in the range of 5.0 to 5.5 GJth/ton clinker.• The incremental energy consumption estimates are similar and give a minimum at 5.1 F0/FCO2 with a value of 2.5 GJth/ton CO2 avoided.

88

90

92

94

96

98

100

0

2

4

6

8

10

12

0 1 2 3 4 5

CO

2 avoidance rate [%]

Incr

emen

tal e

nerg

y co

nsum

ptio

n pe

r CO

2av

oide

d [G

J th/t

on C

O2 a

void

ed]

F0/FCO2

Energy Consumption without Heat RecoveryAt oxy-calcinerEnergy Consumption with Heat RecoveryAt oxy-calcinerCarbon Dioxide Avoidance RateAt oxy-calciner

90% CO2 recovery in the carbonator 90% CO2 avoidance

Alternative CO2 Capture OptionsAlternative CO2 Capture Options

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• Indirect calcination: Tackles CO2 emission resulting from limestone calcination1

• Hybrid configuration: An additional CO2 capture unit (amine) combined with the indirect calcination process to improve CO2 avoidance rate

• Standalone amine process: A retrofit integration including a CHP plant for steam generation

Rodriguez et al., I&ECR, 2126, 2011.

Process Integration – Indirect CalcinationProcess Integration – Indirect Calcination

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• Limestone and clay minerals are fed into two separate raw mills• 10% calcination in the preheater • Potential air leakages have been neglected

(negative impact on CO2 purity)

Process Integration – Hybrid and AmineProcess Integration – Hybrid and Amine

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• Solvent: 30 wt% MEA• Steam source: CHP Plant• SCR and FGD units for NOx and SOx emissions• CO2 avoidance rate is set to 90% by adjusting capture efficiency in the absorber

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• A vacuum pressure of 0.22 bar and feed pressure of 1.1 bar to give a pressure ratio of 5, which was reported as economically affordable1

• Commercial membrane, PolarisTM with a CO2 permeance of 1000 GPU and CO2/N2, CO2/O2 and CO2/H2O selectivities of 50, 10 and 0.2, respectively2

• Two feed gas locations: Option 1, preheater exit gas stream (32 mol%); Option 2, end-of-pipe gas stream (22 mol%)• Four dual stage configurations: different combinations using counter-current and cross flow modules

Process Integration – Membrane ProcessProcess Integration – Membrane Process

1 Merkel et al., Journal of Membrane Science, 126, 2010. 2 Merkel et al., Journal of Membrane Science, 441, 2012 .

Results - ComparisonResults - Comparison

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CO2 capture technology Indirect

calcination Hybrid process

Amine process

Membrane process

Type of integrationOnly hot solid

circulation Flue gases from the kiln and combustor

Flue gases from the CHP and cement plants

Retrofit or 1st

preheaterCO2 capture efficiencies (%)

CO2 capture rate

CO2 avoidance rate (%)

Net power generation (MWe)

Energy Consumption (GJth/ton CO2 avoided)

-

56

– 19

0.9

85

90

– 20

3.3

95

90

+ 8

8.2

90

90

– 31

2.0 – 2.1

4. Economic Analysis4. Economic Analysis

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• The final conclusion of the comparison of various different system integrations should take economic feasibility into consideration

• Levelised cost of cement production (LCOC) has been estimated for the base cement plant and the capture cases

• The cost of CO2 avoided can be calculated from the increase in LCOC

• Levelised cost of cement production – ratio of the net present value of total capital, variable and operating costs of a cement plant to the net present value of cement production over its operating life

IEA, CO2 Capture in the Cement Industry, July 2008/3, 2008.

• TCRt total capital requirement • Mt O&M cost • Vt variable cost, Ct cement production rate • Cc carbon capture process • t and r are the operating year and discount rate

Economic AnalysisEconomic Analysis

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• The main financial assumptions were taken from IEA1 and IEA GHG R&D programme Technical & Financial Assessment Criteria2

• The reference cost data were updated using the six-tenths rule and the M&S index• The fuel and raw material costs were taken from IEA1, DOE3, etc.• As a base approach, the same electricity cost was utilized as revenue for surplus power generation4

• The additional benefits from ETS is included5

(industries emitting CO2 pay a 14 €/ton CO2)• The following equation proposed by Abad et al6 was employed to estimate the cost of CuO/Al2O3 sorbent. Cm was given as 1 $/kg OC

1 IEA, CO2 Capture in the Cement Industry, July 2008/3, 2008. 2 IEA GHG, Technical & Financial Assessment Criteria. 2003. 3 DOE Greenhouse Gas Emissions Control by Oxygen-firing in CFB, 2003. 4 Rodriguez et al., ES&T, 2460, 2012.5 IEA GHG, Biomass CCS Study, 2009. 6 Abad et al., Chem. Eng. Sci., 533, 2007.

Results – Cost EstimatesResults – Cost Estimates

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0

40

80

120

160

200

Base Cement Plant

Ca-looping (0.6)

Ca-Cu looping (0.02)

Indirect Calcination

Amine Process

Hybrid Process

Membrane Process

LC

OC

[€/to

n ce

men

t]

ETS

Variable

O&M

TCR

0

30

60

90

120

150

180

Ca-looping (0.6)

Ca-Cu looping (0.02)

Indirect Calcination

Amine Process

Hybrid Process

Membrane Process

Cos

t of C

O2

avoi

ded

[€/to

n C

O2av

oide

d]

Important sensitivities: • Revenue of power

generation• Reuse of CLC sorbent• Grid emission factor• Emission regulations All results are for 90% CO2 avoidance

The values in the parentheses refer to F0/FCO2 ratio

5. Conclusions5. Conclusions

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• Different ways of capturing CO2 from cement plants by integrating it with Ca-looping, Ca-Cu looping, indirect calcination, amine and membrane processes have been investigated

• The base cement plant is in good agreement with those reported in the literature

• The gas stream leaving the 3rd preheater was selected to be a feed suitable for the carbonator sinceo it does not have to be preheatedo it has a higher CO2 partial pressure and lower total volumetric flow rateo a simpler design of steam cycle for heat recovery is possible

• The fuel consumption of 2.5 to 3.0 GJ/ton CO2 avoided which depends on the F0/FCO2 ratio with a heat recovery system is estimated for the Ca-looping process, while the cost is in the range of 41 – 45 €/ton CO2 avoided

ConclusionsConclusions

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• The energy consumption reduces to 1.7 GJth/ton CO2 avoided in the Ca-Cu looping process because of the absence of an ASU, but the cost of sorbent is the major concern for this system.

• It was presented that the indirect calcination process can provide partial CO2

reduction (56%) when it is properly integrated to a cement plant• The hybrid process provides improvements in energy consumption and cost

compared to the standalone amine process• Membrane process is competitive with the Ca-looping process in terms of

energy consumption and cost

• For more details on all the projects from our group please see http://www.eng.ed.ac.uk/carboncapture/

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Acknowledgements

• Carbon Capture Group Members • Financial Support: Turkish Ministry of Education• Honeywell for providing UniSim® R400 software

Part of this work was awarded the first prizeat the 2013 UniSim Design Challenge Student Competition for Europe, Middle East and Africa