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Research ArticleExperimental Investigation of CaMnO

3Based Oxygen CarriersUsed in Continuous Chemical-Looping Combustion

Peter Hallberg,1 Malin Klln,1 Dazheng Jing,2 Frans Snijkers,3

Jasper van Noyen,3 Magnus Rydn,1 and Anders Lyngfelt1

Department of Energy and Environment, Chalmers University of echnology, Gothenburg, Sweden Department of Inorganic Environmental Chemistry, Chalmers University of echnology, Gothenburg, Sweden

Flemish Institute for echnological Research (VIO), Mol, Belgium

Correspondence should be addressed to Peter Hallberg; [email protected]

Received December ; Revised March ; Accepted April ; Published June

Academic Editor: Jerzy Badyga

Copyright Peter Hallberg et al. Tis is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Tree materials o perovskite structure, CaMn1MO3 (M = Mg or Mg and i), have been examined as oxygen carriers incontinuous operation o chemical-looping combustion (CLC) in a circulating uidized bed system with the designed uel power W. Natural gas was used as uel. All three materials were capable o completely converting the uel to carbon dioxide and wateratC. All materials also showed the ability to release gas phase oxygen when uidized by inert gasat elevated temperature (

C); that is, they were suitable or chemical looping with oxygen uncoupling (CLOU). Both uel conversion and oxygen releaseimproved with temperature. All three materials also showed good mechanical integrity, as the raction o nes collected duringexperiments was small. Tese results indicate that the materials are promising oxygen carriers or chemical-looping combustion.

1. Introduction

Combustion o ossil uels results in increased concentrationo the greenhouse gas CO2in the atmosphere. As the globalconsumption o ossil uels continues to increase, limitingglobal warming to the internationally agreed upon target C

[] will be difficult. All possible tools will likely be neededi this effort is to be successul. One such mitigation tool iscarbon capture and storage (CCS) []. Te basic idea withCCS is to capture the CO2 rom large emission sources, orexample, ossil ueled power plants and industrial processes.Te captured CO2can then be compressed and transportedto a storage site, which can be, or example, a deep salineaquier or a depleted natural gas eld. With CCS ossil uelscan be utilized without contributing to anthropogenic climatechange. Tere are various ways to separate CO2 rom otherue gases and they typically come with a signicant energypenalty [].

2. Background

.. Chemical-Looping Combustion. Chemical-looping com-bustion (CLC) is a uel oxidation process with inherent CO2separation. In CLC oxygen is provided to the uel with a solidoxygen carrier, which is usually a metal oxide (MeO). A

system where the oxygen carrier is continuously circulatedbetween two reactors has been successully tested in differentscales []. Several reviews o chemical-looping combustionresearch and development have been made in the last years[]. A schematic image o the general principle is shown inFigure.

In the uel reactor (FR) the uel is oxidized by the oxygencarrier, according to reaction (). Te ue gases consist omainly CO2 and steam. Steam is easily condensed so thatalmost pure CO2 remains. So by preventing dilution o theue gases with nitrogen rom the air no energy consuminggas separation is needed to obtain CO2 o sufficiently high

Hindawi Publishing CorporationInternational Journal of Chemical EngineeringVolume 2014, Article ID 412517, 9 pageshttp://dx.doi.org/10.1155/2014/412517
http://dx.doi.org/10.1155/2014/412517http://dx.doi.org/10.1155/2014/412517

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International Journal o Chemical Engineering

FRAR

FuelAir

N2 H2O+CO2MexOy

MexOy1

F : A schematic picture o the CLC process.

purity or transport and storage. Tis makes CLC an almostideal technology or CCS. Another important advantage overconventional combustion is that dueto the relatively low tem-perature used, typically around C, thermal NOx or-mation is avoided []. Afer the uel oxidation, the oxygen

depleted oxygen carrier is circulated to the air reactor (AR)to be reoxidized with air, according to reaction (). Consider

CH2+(2 + ) MeO CO2+ H2O+(2 + ) MeO1

()

O2+ 2MeO1 2MeO ()

Note that the sum o reactions () and () is identical toconventional combustion and thus the heat output romCLC is the same as conventional combustion. Reaction () istypically considered as a gas-solid reaction. So when the uelis a solid, such as coal or biomass char, an intermediate step is

needed where the char is gasied. Tis can be done accordingto reaction () or reaction () using steam or CO2as reagent.However, i the oxygen carrier is chosen so that oxygen ingas phase is released spontaneously at FR conditions (hightemperature, low oxygen partial pressure) this intermediatestep is not needed. Tis concept with gas phase oxygenrelease rom the oxygen carrier is called chemical loopingwith oxygen uncoupling (CLOU) [] and is described byreaction (). Consider

C+CO2 2CO ()

C+H2OH2+CO ()

MeOMeO1+12 O2 ()

Oxygen released via reaction () will react with char in anordinary combustion reaction without diluting the ue gaswith nitrogen and the reduced oxygen carrier can be reoxi-dized in the air reactor via reaction (). Te sum o reactionsis the same as orCLC butthe slow gasication steps reactions()-() can be avoided. Tis makes CLOU an attractiveconcept mainly or oxidation o solid uels.

CLOU is also highly interesting or gaseous uels applica-tion as well since it has the potential to improve uel conver-sion by providing oxygen or gas-gas reaction, in addition tothe gas-solid reaction between uel and oxygen carrier.

.. Oxygen Carriers of Perovskite Structure. Te ability o anoxygen carrier to release gas phase oxygen in the chemicallooping uel reactor is dictated by its thermodynamic proper-ties. Metal oxides which are suitable or CLOU include CuO,Mn2O3, andvarious combined oxidessuch as (Mn, Fe)2O3[,]. Another option which has been examined is CaMnO3which is a material o perovskite structure. A material operovskite structure has the general ormula ABC3, whereA and B are a large cation and a small cation, respectively, C isusually oxygen, and in that caseexpresses the oxygen de-ciency in the structure.A orB doesnot haveto be a singleionbut combinations o ions o similar size and oxidation stateare possible. For the use as oxygen carrier other alternativesthan manganese or the B site are iron, titanium, and possiblycopper, nickel, or cobalt. For the A site calcium seems to bethe best candidate although lanthanum and strontium areother possibilities. Te ormability o materials o perovskitestructure has been extensively investigated by Li et al. [ ]What makes perovskites interesting or chemical-loopingcombustion is that the oxygen deciency is a unction

o the surroundings; that is, it changes depending on actorssuchas temperature,pressure, and ambient partial pressureooxygen. In the uel reactor with low oxygen partial pressure would increase, thus releasing oxygen, whereas it woulddecrease in the air reactor with comparatively high oxygenpartial pressure. Tese changes do not necessarily occurat conditions relevant or chemical-looping combustion orall perovskite materials, but in CaMnO3 they do. Alas,Bakken et al. have shown that CaMnO3 decomposes toCa2MnO4 and CaMn2O4 under CLC conditions []. Instudies by Leion et al. [] and Ryden et al. [] a CaMnO3particle doped with titanium has shown high oxygen releaseto inert atmosphere as well as high methane conversion. Tetitanium was incorporated in the crystal structure and is

believed to stabilize the perovskite, to some extent preventingdecomposition to Ca2MnO4 and CaMn2O4. Fossdal et al.[] showed that these kinds o materials can be made usingcheap Mn-ore and calcium hydroxide as raw materials.

In the materials used in the current study some o themanganese hasbeen exchanged to magnesium or magnesiumand titanium. Te magnesium ion is however not o the rightsize to t into the perovskite structure. In X-ray diffractionpatterns the magnesium appeared as periclase (MgO) sep-arate rom the perovskite structure in the three materials.Tis phenomenon is more extensively discussed elsewhere[,,].

.. Te Aim of Tis Study. Te oxygen carriers used in thisstudy have previously been successully examined in a batchreactor [,,] with very positive results. Te goal o thepresent studyis to show that these ormulationso CaMnO3can be used as oxygen carriers also in continuous chemical-looping combustion/oxygen uncoupling. Tis means that thematerials would need to be stableover many hours o uidiza-tion and or hundreds or thousands o redox cycles.

3. Experimental

.. Manufacturing of Oxygen-Carrier Particles. All oxygen-carrier particles examined in this study were manuacturedby VIO in Belgium by spray drying. Te general procedure

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: Material data.

Composition Solids inventory [g] Calcination temperature [C] Bulk density [kg m3]

CaMn.Mg.O3

CaMn.Mg.O3

CaMn.Mg.i.O3

Reactor system

F : Te reactor. Arrows are showing the ow direction o theparticles. Te air reactor is in blue, the uel reactor is in red, and thedowncomer andslot loop seals are shown in green. Te pipes are thevarious gas inlets. In the slot and downcomer the bottom gas inletsconsist o two separate pipes in order to distribute the gas evenlybetween the uel reactor and air reactor side. In the downcomer oneadditional gas inlet sits at about hal height and can be used in case

o uidization difficulties. Not shown in the image is the widenedsettling zone where the gas velocity is reduced so that particles allback down into the reactor. Image courtesy o Patrick Moldenhauer.

was as ollows. Powder mixtures o the raw materials weredispersed in deionized water containing organic additives,organic binder, and dispersants. Te water-based suspensionwas continuously stirred with a propeller blade mixer whilebeing pumped to a -uid nozzle, positioned in the lowercone part o the spray-drier. Obtained particles were sievedand the raction within the desired size range (diameter m) was separated rom the rest o the spray-dried products. Sieved particles were then calcined in air at

or

C or h. Afer calcination, the particles weresieved once more so that all particles used or experimentalevaluation would be o well-dened size.

Te compositions, calcination temperature, bulk density,and the solids inventory used during the experiments areshown in able.

.. Reactor System. Te reactor used or continuous testinghas previously been used by Moldenhauer et al. [,,]with a different uel injection system and by Hallberg et al.[]. A schematic picture o the reactor is shown in Figure .Te reactor is designed to use a rather small amount ooxygen carriers with gaseous uel. Te amount o oxygencarrier required to operate the reactor depends on the density

o the oxygen carrier and is in the range g. Teinner dimensions o the AR are mm mm in the baseand decrease to mm mm in the riser section. Teinner dimension o the FR is mm mm. Te innerdimensions o the downcomer are mm mm. Tegas to the AR and FR enters wind boxes and is evenlydistributed over the cross section by porous quartz plates.In the downcomer and bottom loop-seal (slot) gas entersthrough the pipes seen in Figure. Tese inlets are dividedin two so that one inlet is on the FR side and the other is onthe AR side. Te gas is distributed through small holes drilledin the pipes directed downwards. Te air ow in the AR issufficiently high to throw the particles upwards to a wider

settling zone (not shown in Figure) where they all down.A raction o the alling particles enters the downcomer loopseal. Via the return orice they all into the bubbling uelreactor where they are reduced according to reaction () or(). Te height rom the bottom o the FR to the return oriceis mm. From the bottom o the FR the particles enter theslot loop seal and return to the AR where they are reoxidizedaccording to reaction () and the loop is completed. o beable to operate the reactor at target temperature it is placedinside an electrically heated urnace since the scale is toosmall or autothermal operation. Te oxygen depleted airrom the AR passes through particle lter while the ue gasesrom the FR pass through a particle lter and water seal,

beore leaving the reactor system. Slip streams are extractedafer both the air reactor and the uel reactor and are takento gas conditioning systems, in which each slip stream isurther ltrated and water is condensed. Following the gasconditioning systems the concentrations o O2, CO2, CO,and CH4 are measured continuously using a combinationo inrared and paramagnetic sensors. N2 and H2 rom theFR are measured periodically by gas chromatography (GC).Te gases in the AR and FR are somewhat diluted by the gasthat uidizes the slot. Te gases are urthermore diluted withthe gas rom the downcomer when it leaves the AR/FR anddry gas concentrations measured are thus slightly lower thanwhen leaving the reactor. For the experiments perormed the

ows used are AR= LNmin1

air or nitrogen diluted air,FFR= .. LNmin

1 CO2or natural gas,DOWNCOMER=.LNmin

1 each,SLO = .LNmin1 each; downcomer

and slot were both uidized with argon.

.. Oxygen Uncoupling Experiments. During the startup oexperiments air was used to uidize the reactor during heat-up to the desired temperature. Afer that the uel reactorwas uidized with inert gas in order to study the particlesability to release oxygen. During the oxygen uncouplingexperiments the AR was uidized either with air or withair diluted with nitrogen to an oxygen concentration o %.Te FR was uidized with CO2and the slot and downcomer

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: List o experiments with natural gas.

Experiment Operation (min) FR(LNmin) AR(LNmin

) FR(C)

CaMn.Mg.O3CLCI .

CLCII . -

CLCIII . -

CLCIV . CaMn.Mg.O3

CLCV ..

CLCVI . -

CLCVII .

CLCVIII .

CaMn.Mg.i.O3CLCIX .

CLCX . -

CLCXI . -

CLCXII . -

CLCXIII . -

were uidized with argon. Te reason or examining twodifferent oxidation cases is that the actor in perovskitematerials is known to be a unction o oxygen partialpressure.Hence oxidation with air may provide an overestimation othe capability o the particles during practicable conditions.Oxidation with % oxygen was used to mimic the expectedconditions at the top o the riser in a real-world unit operatingwith % excess air and constitutes a more realistic case.

Tere was some leakage o gas rom the AR to the FRwhich affected the measured raw data slightly. Te leakagewas quantied with the GC by N2measurement. Te leakagewas located to the top o the reactor, that is, over the uidizedbed. Hence the minor amounts o the oxygen that leaked

rom the AR are unlikely to have affected the oxygen releasebehavior. Te measured oxygen concentration was thereorecorrected with the ollowing equation to disregard the leakedoxygen:

O2,corrected FR= O2,FR N2,FR

1 O2,AR /O2 ,AR, ()

where , is the measured molar raction o species exitingthe reactor. Since the N2: O2ratio o the leaked gas is knownthe N2 in the uel reactor is used to quantiy how much O2accompanied it. Basically, ormula () just corrects oxygenrelease data or the small amounts o air leaking rom the topo the air reactor to the top o the uel reactor.

.. Experiments with Natural Gas. During the experimentswith natural gasthe AR wasuidizedwith air, thedowncomerand slot with argon and the uel reactor with natural gas(% methane), or natural gas diluted with nitrogen. Tetemperature in the air reactor was K higher than in theuel reactor during uel operation. Te temperature difference

varied with uel ow and uel conversion. A higher airreactor temperature will reduce the oxygen carrier degreeo oxidation and consequently the uel conversion. Tatproblem would not occur in a commercial scale unit whereheat extraction probably would be in the air reactor. In thisstudy most ocus is put on the relatively slow oxygen carrierreduction rather than oxidation. A consequence o this is that

when temperature is used it is the uel reactor temperature,where the oxygen carrier reduction occurs. As a measure orcombustion efficiency CO2yield,, is used. Te CO2yield isdened as CO2exiting the uel reactor divided by all carboncontaining species as

= CO2

CO2 + CO+ CH4, ()

where is the measured molar raction o species . Tis givesa value close to the combustion efficiency since the heating

value o methane is similar to that o CO and correspondingamount o H2. Possible leakage o carbon containing speciesrom the FR to the AR is not taken into account.

4. Results

.. Oxygen Uncoupling Experiments. Te temperaturedependence o oxygen uncoupling is shown in Figures(a)(c). Te gures show the oxygen concentration calculatedaccording to () o the gas leaving the FR as a unction otemperature in FR or two different oxygen partial pressuresin the AR. As expected the oxygen release increased withtemperature. Tis is most noticeable between and C.Te partial pressureo oxygen in the AR also had aneffect onoxygen release. Te was obviously greater in the case withair or oxidation compared to the % oxygen case. When airwas used or oxidation the measured oxygen concentrationor gas leaving the air reactor was above %. Oxidation wasthereore done with a large excess o oxygen. For the casewhen % oxygen was used to uidize the air reactor themeasured outgoing oxygen concentration was about %.CaMn0.8Mg0.2O3gave the highest oxygen concentration inthe uel reactor. However, all three materials tested provedto be potent oxygen uncouplers. It can also be noted that theamount o leakage differed or the different particles but thatis unlikely to have had any inuence on the results.

.. Experiments with Natural Gas. Te experimental con-ditions that were used are listed in able . Operationalparameters were adjusted in order to operate at ull uel

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O2

concentrationFR

(%)

Fuel reactor temperature(C)

21% O2

5% O2

8

6

4

2

0

700 800 900 1000

(a)

O2

concentrationFR

(%)


21% O2

5% O2

8

6

4

2

0

700 800 900 1000

(b)

O2

concentrationFR(%)


21% O2

5% O2

8

6

4

2

0

700 800 900 1000

(c)

F : Effect o temperature and AR O2 concentration on oxygen uncoupling or CaMn0.8Mg0.2O3 (a), CaMn0.9Mg0.1O3 (b), andCaMn0.775Mg0.1i0.125O3(c). Te oxygen concentration is corrected through ().

conversion or close to it. ypically parameters (air ow, uelow, and temperature) were changed one at a time. For CLCIand CLCVuels were cautiously introduced and or the uel

ow . LNmin1 uel was mixed with nitrogen. Afer the

initial uel introduction was successul uel ow and air owwere tested at other levels as well. Figure shows how the gasconcentrations vary in the transition rom CLCIIto CLCIII.By increasing uel ow the uel conversion goes rom com-plete to incomplete. Tis is seen as the excess oxygen goes tozero and methane and carbon monoxide are >. Te increasein oxygen at min is due to a leakage while controlling alter. At experiments CLCIVand CLCVIIa temperature stair

wastested. Te temperature wasgradually increasedrom to C.

Te effect o temperature on the combustion efficiencycan be seen in Figure. Here all three materials reach com-plete or almost complete uel conversion. For these exper-iments the ows used are AR = LNmin

1, FR = .,DOWNCOMER= . LNmin

1 each, andSLO= . LNmin1

each. In Figure the combustion efficiency is shown as aunction o uel reactor particle load per uel power. Teuel reactor inventory is estimated to be % o the totalinventory based on measured bed heights afer experimentstermination. While particle inventory was held constant

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0

1

2

3

4

5

O2FR

CO2FR

O2AR

CO2AR

CH4FR

CO FR

Time (min)

XCO2,FR

,XO2,AR(%)

0 40 80 120

40

20

0XCH4,FR,XCO,FR,XO2,FR,XCO2,AR(%)

F : Measured dry gas composition or the transition romCLCII to CLCIII. What can be seen is an instance when goingrom . LNmin

1 uel ow to ..AR is held at LNmin1. Teoperation goes rom complete uel conversion with excess oxygento incomplete uel conversion.

during experiments the parameter was changed by varying

the uel ow between . and . LNmin1.

In general, the experiments with natural gas pro-ceeded quite smoothly. Tere were some problems withCaMn0.8Mg0.2O3 and CaMn0.9Mg0.1O3 when the tem-perature was increased to C though. At these temper-atures the circulation o solids appears to have been nega-tively affected and the uel conversion decreased. However,once uel was switched to inert gas and the temperaturereduced stable operation could be resumed. CaMn0.775Mg0.1

i0.125O3 on the other hand could be operated withoutproblems at C.

.. Particle Integrity. Te tests with CaMn0.8Mg0.2O3andCaMn0.9Mg0.1O3 unortunately had to be aborted beoreschedule. Te premature termination o experiments was dueto signicant particle leakage rom the reactor system to thesurroundings due to mechanical ailure. Tus the attrition oCaMn0.8Mg0.2O3 and CaMn0.9Mg0.1O3 particles is esti-mated through what was ound in lters afer experiments.For CaMn0.8Mg0.2O3. g o nes was ound in lters andwater seal afer operation which would correspond to .%particles lost per hour o uel operation. Tat number would

be considerably smaller i operation at hot conditions withuidization was used as base rather than operation with uel.With CaMn0.9Mg0.1O3not all the particles ound in lterswere nes (

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212

Massfraction(%)

Particle diameter(m)

80

60

40

20

0

Fresh

Used

F : Particle size distribution or CaMn0.775Mg0.1i0.125O3,comparison between resh particles added to reactor and theretrieved used ones.

well. Using the same measure as above the loss o particleswas .% per hour o uel operation.

.. Effects of Operation. It was noticed during the operationwith CaMn0.775Mg0.1i0.125O3 that the reactivity seemedto decrease slightly as a unction o operation time. Tisphenomenon was examined by testing the reactivity o theused particles in a small batch reactor. Te experiments wereperormed using the same equipment and methodology asHallberg et al. [] did in a previous study. Tus the reactivityo resh particles and the particles that had been used in the W unit could be examined, isolating possible sources oerror such as rate o solids circulation. Te comparison ispresented in Figure, in which data or CaMn0.9Mg0.1O3also have been included. A reduced CO2 yield or used

oxygen carrier particles can be seen or both materials. Teeffect on CaMn0.775Mg0.1i0.125O3 is considerably largerthan or CaMn0.9Mg0.1O3 though. A possible explanationorthe larger impact o operation on this material is operatingtime. CaMn0.9Mg0.1O3 was tested or h with uel inthe continuous unit whereas CaMn0.775Mg0.1i0.125O3wastested ormore than h. Oxygen release to inert atmospherewasalso examined in batchreactor but the difference betweenused and resh particles was very small, as shown in Figure.In an attempt to explain the decrease in reactivity theparticles were examined by X-ray powder diffraction. ForCaMn0.9Mg0.1O3 an increase in the marokite (CaMn2O4)peaks was detected. A comparison o the resh and used

CO2

yield,

()

CaMn0.9Mg0.1O3resh

CaMn0.9Mg0.1O3used

CaMn0.775Mg0.1Ti0.125O3used

CaMn0.775Mg0.1Ti0.125O3resh

Degree o reduction,()

1

0.8

0.6

0.4

0.2

1 0.995 0.99 0.985 0.98 0.975

F : CO2 yield as a unction o degree o reduction. Resultsrom reduction with methane in quartz batch reactor. Fresh particlesare compared with materials used in the W unit. Tese resultsare perormed at C.

O2

concentration(%)

Time (s)

6

4

2

0

0 100 200 300 400

CaMn0.9Mg0.1O3resh

CaMn0.9Mg0.1O3used

CaMn0.775Mg0.1Ti0.125O3used

CaMn0.775Mg0.1Ti0.125O3resh

F : Outgoing oxygen concentration during batch experi-ments. Te uidizing gas is changed rom % oxygen in nitrogen to% nitrogen at time . Te s delay is the time it takes or gas toreach gas analyzer. Fresh particles are compared to particles whichhave been used in the W unit.

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C14

Counts

C14resh.raw

C14used afer300 w.raw (Y-offset)

PDF04-012-5765CaMnO2.97calcium manganese oxide

PDF01-077-2906Mgo periclase, synPDF04-009-1090CaMn2O4marokite

1000

900

800

700

600

500

400

300

200

100

020 30 40 50 60 70 80 90 100

2WL= 1054060

F : X-ray diffraction pattern including resh and usedCaMn0.9Mg0.1O3. An increase in the CaMn2O4peaks (in magentaat , , , and ) can be seen in the used particles.

particles is shown in Figure. Te decomposition was notdetected or CaMn0.775Mg0.1i0.125O3.

5. Discussion and Conclusions

Te purpose o this work is to investigate materials otherthan nickel oxide materials, representing the state o art orchemical-looping combustion o gaseous uels. Te results are

highly encouraging as ollows:

(i) the materials studied are able to reach complete gasconversion in contrast to nickel oxide materials whichare limited to % conversion;

(ii) the materials studied are composed o raw materialsvery much cheaper than nickel oxide;

(iii) the materials studied are not associated with signi-cant risks or health and environment in contrast tonickel;

(iv) the materials seem to have low attrition rates.

Te experimental campaign was thus, despite a ew minorsetbacks, a success. In addition to the points made above:

(i) all three tested materials released oxygen to inertatmosphere;

(ii) or CaMn0.8Mg0.2O3 a FR particle inventory o kg/MWth was needed or complete natural gasconversion at C and or CaMn0.9Mg0.1O3 theFR particle inventory needed was kg/MWth.CaMn0.775Mg0.1i0.125O3reached complete conver-sion at a FR particle inventory o kg/MWth orC and kg/MWthor

C.

Notations

AR: Air reactorFR: Fuel reactor: Volume ow in inlet: emperature in reactor: Molar raction o species,: Molar raction o speciesin reactor: CO2-yield: Oxygen deciency in perovskite structure: Oxygen carrier degree o oxidation.

Conflict of Interests

Te authors declare that there is no conict o interestsregarding the publication o this paper.

Acknowledgment

Tis research has received unding rom the European UnionSeventh Framework Program (FP/) via Grantagreement no. .

References

[] Copenhagen Accord,U.N. Framework Convention on ClimateChange, .

[] M. E. Boot-Handord, J. C. Abanades, E. J. Anthony et al.,Carbon capture and storage update,Energy & EnvironmentalScience, vol. , pp. , .

[] P. Kolbitsch, J. Bolhar-Nordenkamp, . Proll, and H. Hoauer,Operating experience with chemical looping combustion in a

kW dual circulating uidized bed (DCFB) unit, Interna-tional Journal of Greenhouse Gas Control, vol. , no. , pp. , .

[] C. R. Forero, P. Gayan, L. F. de Diego, A. Abad, F. Garca-Labiano, and J. Adanez, Syngas combustion in a Wthchemical-looping combustion system using an impregnatedCu-based oxygen carrier, Fuel Processing echnology, vol. ,no. , pp. , .

[] H. R. Kim, D. Wang, L. Zeng et al., Coal direct chemical loop-ing combustion process: design and operation o a -kWthsub-pilot unit,Fuel, vol. , no. , pp. , .

[] C. Linderholm, . Mattisson, and A. Lyngelt, Long-termintegrity testing o spray-dried particles in a -kW chemical-looping combustor using natural gas as uel,Fuel, vol. , no.

, pp. , .[] L.-S. Fan, Chemical Looping Systems for Fossil Energy Conver-

sion, John Wiley & Sons, .

[] J. Adanez, A. Abad, F. Garcia-Labiano, P. Gayan, and L. F. DeDiego, Progress in chemical-looping combustion and reorm-ing technologies,Progress in Energy and Combustion Science,vol. , no. , pp. , .

[] A. Lyngelt, Chemical-looping combustion o solid uelsstatus o development,Applied Energy, vol. , pp. ,.

[] M. Ishida and H. Jin, A novel chemical-looping combustorwithout NOx ormation,Industrial and Engineering ChemistryResearch, vol. , no. , pp. , .

8/12/2019 412517

9/10


[] . Mattisson, A. Lyngelt, and H. Leion, Chemical-looping withoxygen uncoupling or combustion o solid uels, InternationalJournal of Greenhouse Gas Control, vol. , no. , pp. , .

[] M. Ryden, H. Leion, . Mattisson, and A. Lyngelt, Combinedoxides as oxygen-carrier material or chemical-looping withoxygen uncoupling, Applied Energy, vol. , pp. ,.

[] C. Li, K. C. K. Soh, and P. Wu, Formability o ABO per-ovskites,Journal of Alloys and Compounds, vol. , no. -, pp., .

[] E. Bakken, . Norby, and S. Stlen, Nonstoichiometry andreductive decomposition o CaMnO-,Solid State Ionics, vol., no. -, pp. , .

[] H. Leion, Y. Larring, E. Bakken, R. Bredesen, . Mattisson, andA. Lyngelt, Use o CaMn0.875i0.125O3 as oxygen carrier inchemical-looping with oxygen uncoupling,Energy and Fuels,vol. , no. , pp. , .

[] M. Ryden, A. Lyngelt, and . Mattisson, CaMn0.875i0.125O3asoxygen carrier or chemical-looping combustion with oxygenuncoupling (CLOU)experiments in a continuously operating

uidized-bed reactor system,International Journal of Green-house Gas Control, vol. , no. , pp. , .

[] A. Fossdal, E. Bakken, B. A. ye et al., Study o inexpensiveoxygen carriers or chemical looping combustion, Interna-tional Journal of Greenhouse Gas Control, vol. , no. , pp. , .

[] P. Hallberg, D. Jing, M. Ryden, . Mattisson, and A. Lyngelt,Chemical looping combustion and chemical looping withoxygen uncoupling experiments in a batch reactor using spray-dried CaMn-xMxO- (M = i, Fe, Mg) particles as oxygencarriers,Energy and Fuels, vol. , no. , pp. , .

[] M. Ryden and M. Arjmand, Continuous hydrogen productionvia the steam-iron reaction by chemical looping in a circu-lating uidized-bed reactor,International Journal of Hydrogen

Energy, vol. , no. , pp. , .[] D. Jing,. Mattisson, M. Ryden et al., Innovativeoxygen carrier

materials or chemical-looping combustion,Energy Procedia,vol. , pp. , .

[] D. Jing, . Mattisson, H. Leion, M. Ryden, and A. Lyngelt,Examination o perovskite structure CaMnO- with MgOaddition as oxygen carrier or chemical looping with oxygenuncoupling using methane and syngas, International Journalof Chemical Engineering, vol. , Article ID , pages,.

[] P. Moldenhauer, M. Ryden, . Mattisson, and A. Lyngelt,Chemical-looping combustion and chemical-looping reorm-ing o kerosene in a circulating uidized-bed W laboratoryreactor, International Journal of Greenhouse Gas Control, vol.,

pp. , .

[] P. Moldenhauer, M. Ryden, . Mattisson, M. Younes, and A.Lyngelt, Te use o ilmenite as oxygen carrier with kerosenein a W CLC laboratory reactor with continuouscirculation,Applied Energy, vol. , pp. , .

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