techno-economic study of co capture from a … capture and storage (ccs) 4 a promising and an...
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Techno-Economic Study of CO2 Capture from a Cement Plant
Dursun Can Ozcan, Hyungwoong Ahn, Stefano [email protected]
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
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• 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