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