Modelling of an Entrained Flow CaL Carbonator for CO2 Capture in Cement Kilns
Maurizio Spinelli PhDIsabel Martinez PhDEdoardo De Lenaprof. Matteo Romanoprof. Stefano Campanariprof. Stefano Consonni
7th High Temperature Solid Looping Cycles Network MeetingLuleå, Sweden, 4-5th September 2017
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 2/20
Outline
Overview of CaL technology in cement plant:
Tail end
Integrated with EF carbonator
1D model of EF carbonator:
Results of first sensitivity analysis
Conclusion
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 3/20
Cement plant and related model
Clinker out
Raw meal* in
Gas out
Air in
Petcoke
65%
35%
CO2 80%
20%
Reference plant GS (POLIMI code)Cement plant is characterized by:
high fuel consumptions: ~ 3.2 MJLHV/kgck high CO2 emissions (~850gCO2/kgCK) from
fuel combustion and CaCO3 decomposition.
CaCO3 CaO+CO2
Calciner
* Mostly CaCO3 + additives like Fe2O3, Al2O3, SiO2, MgCO3
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 4/20
Tail-end CaL configuration
carbonatorcalciner
CaCO3 + correctives
decarbonated flue gasCO2 to
storage
heat for steam generation/raw meal preheating
heat for steam generation/raw meal preheating
High purity O2
fuel
filter
carbonator heat steam generation
CONVENTIONAL CEMENT KILN clinker
CO2-rich gas from the suspension preheater
limestone
CaO-rich CaL purge
ASU
CO2 compression and purification
unit
• Carbonator removes CO2 from cement plant flue gas highly suitable for retrofit• CaO-rich purge from CaL calciner used as feed for the cement kiln• CFB CaL reactors: d50=100-250 μm
Particle size for clinker production d50=10-20 μm CaL purge milled in the raw mill at low temperature
1) Spinelli et al., “Integration of Ca-Looping systems for CO2 capture in cement plants”GHGT13 conference paper, Energy Procedia 114 ( 2017 ) 6206 – 62142) De Lena et al., “Process integration study of tail-end Ca-Looping process for CO2 capture in cement plants ” Submitted to International Journal of Greenhouse Gas Control
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 5/20
Integrated CaL configuration
carbonator
calciner
CO2-rich gas from the kiln
hot clinker
fuel
decarbonated flue gas
heat recovery for steam generation
High purity O2
fuel
filter
clinker coolercooled clinker
cooling air
cooler exhaust airsecondary
airrotary kiln
carbonator heat steam generation
Raw meal preheater 1
Raw meal 1
Raw meal 2
Raw meal preheater 2heat recovery for
steam generation
CaCO3-rich material
precalcined raw meal
ASU
CO2 to storage
CO2 compression and purification
unit
CaL• carbonator highly integrated within the preheating tower, on rotary kiln gasCaL• calciner coincides with the cement kiln pre-calcinerCalcined raw meal as CO• 2 sorbent in the carbonatorSorbent has small particle size (d• 50=10-20 μm) entrained flow reactors
Spinelli et al., “Integration of Ca-Looping systems for CO2 capture in cement plants”GHGT13, Energy Procedia 114 ( 2017 ) 6206 – 6214
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 6/20
Fresh raw meal
Raw meal preheater
CO2-poor flue gas
Fuel
O2
Carb
onat
or
CO2-rich gas to CPU
Fuel
Calc
iner
Recarbonated sorbent + fresh preheated raw
meal to calciner
Calcined raw meal to rotary kiln
Calcined raw meal to carbonator
Rotary kiln
CO2 recycle
Integrated CaL concept: entrained flow (EF) reactors
CO2 from kiln
CO2 to storage
CO2 from calciner
O2 from ASU
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 7/20
Reference cement plant
w/o CO2 capture
Tail-end CaLconfiguration
Integrated CaL
configuration
Direct CO2 emissions [kgCO2/tclk] 863.1 143.2 71.4Indirect CO2 emissions [kgCO2/tclk] 105.2 -123.5 128.7Equivalent CO2 emissions [kgCO2/tclk] 968.3 19.7 200.1Equivalent CO2 avoided [%] -- 98.0 79.3SPECCA [MJLHV/kgCO2] -- 3.26 2.32
Integrated / Tail End CaL concepts: results
Spinelli et al., “Integration of Ca-Looping systems for CO2 capture in cement plants”GHGT13, Energy Procedia 114 ( 2017 ) 6206 – 6214
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 8/20
Entrained flowcarbonator model
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 9/20
CaL• kineticsGas• -solid drag velocitiesInterphase• heat transferExternal• heat transferPressure• lossesFluid• -dynamic checkInternal• sorbent recycle
NASA• polynomials for gas /solid TDN propertiesSteady• stateIncompressible• flowHomogeneous• mixturesMass• transfer effect neglected (low Da numbers)
Main Assumptions
Entrained flow CaL carbonator modelingDilute reactor is the most suitable option for the cement plant CaL application, becauseof the experience with entrained flow technologies and the low particle size.A simple, finite-difference model (axial discretization) has been developed to solve mass,momentum and energy equations and evaluate the potential CO2 capture rate.
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 10/20
Mass
Carbonation kinetics
1 − 𝐺𝐺𝐺𝐺𝐺𝐺:𝑑𝑑�̇�𝑚𝑔𝑔
𝑑𝑑𝑑𝑑= −
�̇�𝑀𝑠𝑠,𝑎𝑎
𝑢𝑢𝑠𝑠�
𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
� 𝑀𝑀𝐶𝐶𝐶𝐶2 2 − 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑑𝑑:𝑑𝑑�̇�𝑚𝑠𝑠
𝑑𝑑𝑑𝑑= −
𝑑𝑑�̇�𝑚𝑔𝑔
𝑑𝑑𝑑𝑑
Temperature influence Xmax influence𝐶𝐶𝐺𝐺𝐶𝐶 𝑠𝑠 + 𝐶𝐶𝐶𝐶 )2(𝑔𝑔
∆ℎ+𝐶𝐶𝐺𝐺𝐶𝐶𝐶𝐶 )3(𝑠𝑠
𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 =
𝑘𝑘𝑠𝑠 � 𝑆𝑆𝑁𝑁
1 − 𝜀𝜀𝑃𝑃� 1 − 𝑑𝑑 � 𝐶𝐶𝐶𝐶𝐶𝐶2 − 𝐶𝐶𝐶𝐶𝐶𝐶2,𝑒𝑒𝑒𝑒 � 1 − Ψ 𝑆𝑆𝑙𝑙 1 − 𝑑𝑑
𝑘𝑘𝑠𝑠 = 𝑘𝑘𝑠𝑠,0 � exp−20300𝑇𝑇𝑅𝑅 � 𝑅𝑅𝑢𝑢
𝑆𝑆𝑁𝑁 = 𝑆𝑆0 � 𝑑𝑑𝑚𝑚𝑎𝑎𝑚𝑚
𝑅𝑅𝐺𝐺𝑙𝑙𝑑𝑑𝑆𝑆𝑚𝑚 𝑃𝑃𝑆𝑆𝑃𝑃𝑃𝑃 𝑚𝑚𝑆𝑆𝑑𝑑𝑃𝑃𝑆𝑆 𝑤𝑤𝑆𝑆𝑑𝑑ℎ 𝑑𝑑𝑚𝑚𝑎𝑎𝑚𝑚 𝒊𝒊𝒊𝒊𝒊𝒊𝒊𝒊𝒊𝒊𝒊𝒊𝒊𝒊
EF carbonator modeling – EquationsDilute reactor is the most suitable option for the cement plant CaL application, becauseof the experience with entrained flow technologies and the low particle size.A simple, finite-difference model (axial discretization) has been developed to solve mass,momentum and energy equations and evaluate the potential CO2 capture rate.
G. Grasa et al., “Application of the random pore model to the carbonation cyclic reaction”, AIChE J. 55 (2009)
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 11/20
Dilute reactor is the most suitable option for the cement plant CaL application, becauseof the experience with entrained flow technologies and the low particle size.A simple, finite-difference model (axial discretization) has been developed to solve mass,
momentum and energy equations and evaluate the potential CO2 capture rate.
Energy5 − 𝐺𝐺𝐺𝐺𝐺𝐺:
𝑑𝑑 �̇�𝑚𝑔𝑔 � ℎ𝑔𝑔 + 0.5 � �̇�𝑚𝑔𝑔 � 𝑢𝑢𝑔𝑔2 + 𝐼𝐼𝐺𝐺 � �̇�𝑚𝑔𝑔 � 𝑔𝑔 � 𝑑𝑑
𝑑𝑑𝑑𝑑= −�̇�𝑤𝑔𝑔𝑠𝑠 − �̇�𝑞𝑔𝑔𝑔𝑔 − �̇�𝑞𝑔𝑔𝑠𝑠 − �̇�𝑞𝐶𝐶𝐶𝐶2,𝑐𝑐𝑎𝑎𝑐𝑐𝑐𝑐
6 − 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑑𝑑:𝑑𝑑 �̇�𝑚𝑠𝑠 � ℎ𝑠𝑠 + 0.5 � �̇�𝑚𝑠𝑠 � 𝑢𝑢𝑠𝑠
2 + 𝐼𝐼𝐺𝐺 � �̇�𝑚𝑠𝑠 � 𝑔𝑔 � 𝑑𝑑𝑑𝑑𝑑𝑑
= �̇�𝑤𝑔𝑔𝑠𝑠 − �̇�𝑞𝑠𝑠𝑔𝑔 + �̇�𝑞𝑔𝑔𝑠𝑠 + �̇�𝑞𝑐𝑐,𝑐𝑐𝑎𝑎𝑐𝑐𝑐𝑐 + �̇�𝑞𝐶𝐶𝐶𝐶2,𝑐𝑐𝑎𝑎𝑐𝑐𝑐𝑐
3-Gas: 𝑑𝑑 �̇�𝑚𝑔𝑔�𝑢𝑢𝑔𝑔
𝑑𝑑𝑚𝑚+ 𝐴𝐴 � 𝑑𝑑𝑑𝑑
𝑑𝑑𝑚𝑚= −𝐼𝐼𝐺𝐺 � 𝐴𝐴𝑔𝑔 � 𝜌𝜌𝑔𝑔 � 𝑔𝑔 − 𝐹𝐹𝑓𝑓𝑔𝑔 − 𝐹𝐹𝑔𝑔𝑠𝑠
4 − 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑑𝑑: 𝑑𝑑 �̇�𝑚𝑠𝑠�𝑢𝑢𝑠𝑠𝑑𝑑𝑚𝑚
= −𝐼𝐼𝐺𝐺 � 𝐴𝐴𝑠𝑠 � 𝜌𝜌𝑠𝑠 � 𝑔𝑔 − 𝐹𝐹𝑓𝑓𝑠𝑠 + 𝐹𝐹𝑔𝑔𝑠𝑠
Momentum
Mass 1 − 𝐺𝐺𝐺𝐺𝐺𝐺:𝑑𝑑�̇�𝑚𝑔𝑔
𝑑𝑑𝑑𝑑= −
�̇�𝑀𝑠𝑠,𝑎𝑎
𝑢𝑢𝑠𝑠�
𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
� 𝑀𝑀𝐶𝐶𝐶𝐶2 2 − 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑑𝑑:𝑑𝑑�̇�𝑚𝑠𝑠
𝑑𝑑𝑑𝑑= −
𝑑𝑑�̇�𝑚𝑔𝑔
𝑑𝑑𝑑𝑑
EF carbonator modeling – Equations
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 12/20
Complementary correlations
Dilute reactor is the most suitable option for the cement plant CaL application, becauseof the experience with entrained flow technologies and the low particle size.A simple, finite-difference model (axial discretization) has been developed to solve mass,momentum and energy equations and evaluate the potential CO2 capture rate.
Energy5 − 𝐺𝐺𝐺𝐺𝐺𝐺:
𝑑𝑑 �̇�𝑚𝑔𝑔 � ℎ𝑔𝑔 + 0.5 � �̇�𝑚𝑔𝑔 � 𝑢𝑢𝑔𝑔2 + 𝐼𝐼𝐺𝐺 � �̇�𝑚𝑔𝑔 � 𝑔𝑔 � 𝑑𝑑
𝑑𝑑𝑑𝑑= −�̇�𝑤𝑔𝑔𝑠𝑠 − �̇�𝑞𝑔𝑔𝑔𝑔 − �̇�𝑞𝑔𝑔𝑠𝑠 − �̇�𝑞𝐶𝐶𝐶𝐶2,𝑐𝑐𝑎𝑎𝑐𝑐𝑐𝑐
6 − 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑑𝑑:𝑑𝑑 �̇�𝑚𝑠𝑠 � ℎ𝑠𝑠 + 0.5 � �̇�𝑚𝑠𝑠 � 𝑢𝑢𝑠𝑠
2 + 𝐼𝐼𝐺𝐺 � �̇�𝑚𝑠𝑠 � 𝑔𝑔 � 𝑑𝑑𝑑𝑑𝑑𝑑
= �̇�𝑤𝑔𝑔𝑠𝑠 − �̇�𝑞𝑠𝑠𝑔𝑔 + �̇�𝑞𝑔𝑔𝑠𝑠 + �̇�𝑞𝑐𝑐,𝑐𝑐𝑎𝑎𝑐𝑐𝑐𝑐 + �̇�𝑞𝐶𝐶𝐶𝐶2,𝑐𝑐𝑎𝑎𝑐𝑐𝑐𝑐
4 − 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑑𝑑: 𝑑𝑑 �̇�𝑚𝑠𝑠�𝑢𝑢𝑠𝑠𝑑𝑑𝑚𝑚
= −𝐼𝐼𝐺𝐺 � 𝐴𝐴𝑠𝑠 � 𝜌𝜌𝑠𝑠 � 𝑔𝑔 − 𝐹𝐹𝑓𝑓𝑠𝑠 + 𝐹𝐹𝑔𝑔𝑠𝑠
Momentum
Mass 1 − 𝐺𝐺𝐺𝐺𝐺𝐺:𝑑𝑑�̇�𝑚𝑔𝑔
𝑑𝑑𝑑𝑑= −
�̇�𝑀𝑠𝑠,𝑎𝑎
𝑢𝑢𝑠𝑠�
𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑
� 𝑀𝑀𝐶𝐶𝐶𝐶2 2 − 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑑𝑑:𝑑𝑑�̇�𝑚𝑠𝑠
𝑑𝑑𝑑𝑑= −
𝑑𝑑�̇�𝑚𝑔𝑔
𝑑𝑑𝑑𝑑
3-Gas: 𝑑𝑑 �̇�𝑚𝑔𝑔�𝑢𝑢𝑔𝑔
𝑑𝑑𝑚𝑚+ 𝐴𝐴 � 𝑑𝑑𝑑𝑑
𝑑𝑑𝑚𝑚= −𝐼𝐼𝐺𝐺 � 𝐴𝐴𝑔𝑔 � 𝜌𝜌𝑔𝑔 � 𝑔𝑔 − 𝐹𝐹𝑓𝑓𝑔𝑔 − 𝐹𝐹𝑔𝑔𝑠𝑠
EF carbonator modeling – Equations
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 13/20
Methodology and scope
Simulation assumptions:Reactor length: • 150 mSorbent nature: calcined raw meal ●(66.1% CaO, 4%CaCO3, 21% SIO2, 3.1% Al2O3, 1.1% Fe2O3, 3.6% MgO, 1.1%CaSO4)
Inlet solid/gas velocities: ● 0/15 m/sInlet solid/gas temperatures: ● 600/600°CIsothermal reactor walls.●
Sensitivity analysis on:Solid loading ● ( ��̇�𝒊𝒊𝒊
�̇�𝒊𝒈𝒈 = 1/3/6);Reactor wall temperature (T● W=260/320/500°C)Carbonators number (● 1/4)Sorbent maximum conversion (X● MAX=10/20/30%).
Definition of reactor boundary conditions and simplified design;1)Calculation of the CO2) 2 capture rate as a function of kinetic models;Identification of the most promising operating parameters.3)
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 14/20
Simulation results (i) – Effect of solid loading (�̇�𝒊𝒊𝒊/�̇�𝒊𝒈𝒈)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 20 40 60 80 100 120 140
CO2
capt
ure
effic
ienc
y
Reactor length [m]
XMax=20%TW=320°CRaw meal as sorbent
𝒊𝒊 ̇_𝒊𝒊/𝒊𝒊 ̇_𝒈𝒈= 3
𝒊𝒊 ̇_𝒊𝒊/𝒊𝒊 ̇_𝒈𝒈= 1
�̇�𝒊𝒊𝒊/�̇�𝒊𝒈𝒈= 6
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 15/20
L=150 m , v=15 m/s L=60 m , v=4 m/s
Alternative geometry: downdraft carbonator
DOWNDRAFTUPDRAFT
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 16/20
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 20 40 60 80 100 120 140
CO2
capt
ure
effic
ienc
y
Reactor length [m]
XMax=20%, TW=320°C- - - - Conventional (vGas=15 m/s)____ Downdraft (vGas=4 m/s)
𝒊𝒊 ̇_𝒊𝒊/𝒊𝒊 ̇_𝒈𝒈=1
Simulation results (ii) – Downdraft vs updraft
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 17/20
Simulation results (iii) : Natural raw meal as sorbent
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 18/20
Simulation results (iv) : Synthetic raw meal as sorbent
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 19/20
Conclusions
A relatively high solid loading (● ms/mg=6÷10) is required for obtaining high capture rates;
Sorbent capacity (● raw meal nature, calcination condition) has a significant impact on carbon capture rate;
Downdraft option allows for higher residence time and higher sorbent ●loadings improves capture rates;
Further research needs :
-properties of different raw meals and calcination conditions on CaO sorbent performance
-fluid dynamics of EF reactor at high solid/gas ratio -experimental validation of the concept under realistic conditions
Entrained flow CaL reactors for CO2 capture in cement plants, 7th HTSLC, Luleå, 4/5-9-2017 20/20
Thank you for your attention!
Activities related to Cemcap project have received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 641185.https://www.sintef.no/projectweb/cemcap/
http://www.leap.polimi.it/leap/http://www.gecos.polimi.it/
ACKNOWLEDGMENTS