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Effect of pressure on chemical

looping combustion of coal with an iron ore based oxygen carrierQilei

Song*,

Rui Xiao,

Shuai Zhang,

Wenguang Zheng,

Yichao Yang , Laihong ShenThermal Engineering Research Institute

School of Energy and EnvironmentSoutheast University, Nanjing 210096, China

qlsong@seu.edu.cn ; ruixiao@seu.edu.cn ; lhshen@seu.edu.cn* Presenter and Current address:

Department of Chemical Engineering & BiotechnologyUniversity of Cambridge

CB2 3RA UKqs209@cam.ac.uk

IFPLyon, France, 1719, March, 2010

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Contents CLC at Southeast University, Nanjing, China

Experiments design

Pressurized steam coal gasification

Effect of pressure on CLC with iron ore

Long cycle performance at typical pressures

Conclusion

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Roadmap (CLC)

Development of Oxygen carriers

Commercialization

Reactivity test with, TGA, FzD

Reactivity test with solid fuels

Performance in large reactor

Performance in pilot scale reactor

Technology Theory

Industrial demonstration

Science of Chemistry & Materials

Kinetics study, thermodynamics

Coal gasification,reaction kinetics

Reactor design and modelling

Scale up and optimization

Scale up

Concept

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Chemical looping at Southeast University

Nanjing, China Laboratory scale reactorTGA, PTGA, fixed bed, fluidized bed, Dual connected fluidized bed (gasifier + CLC), Pressurized fluidized/fixed bed,

Larger scale and pilot scale reactor1kWth CLC combustor10kWth CLC combustor10kWth Chemical looping Hydrogen100 kWth Pressurized CLC Combustor

Publications: 20

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Chemical looping at Southeast University,

Nanjing, China Oxygen carrier developmentNiO/NiAl 2O4, coprecipitation, coal, deactivation

Low cost materialsNonmetal oxide: CaSO4/CaS , powder, anhydrite particleIron oxide, sinteredIron ore, Calcined, from Australia, Brazil, China, etc,

IlmeniteIron oxide scale from steel industryIron Nickel ore

Publications: 14

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Low cost Calcium based CaSO4/CaS cycle

A. Abad et al. Fuel 86 (2007) 10211035

Effect of CaSO4/CH4 Ratio on Equilibrium Composition

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

10

20

30

40

50

60

70

80

90

100

0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.201E-4

1E-3

0.01

0.1

1

10

(b)

CO 2CO

H2

F r a c

t i o n

( m o

l , % )

CaSO 4/CH 4 molar ratio

(a)

CH 4

900o

C

CaSO 4/CH 4 molar ratio

H2O

F r a c

t i o n

( m o

l , % )

CO

H2

H2S

SO 2

COS

S 2

Sulphur release??Song et al, Energy Fuels 2008 , 22 (6), 3661-3672. http://dx.doi.org/10.1021/ef800275aSong et al, Ind. Eng. Chem. Res. 2008 , 47 (21), 8148-8159. http://dx.doi.org/10.1021/ie8007264Song et al, Korean. J. Chem. Eng. 2009 , 26 (2), 592-602. http://dx.doi.org/10.1007/s11814-009-0101-2Song et al, Energy Convers. Manage 2008 , 49 (11), 3178-3187. http://dx.doi.org/10.1016/j.enconman.2008.05.020

Song et al, Ind. Eng. Chem. Res. 2008 , 47 (13), 4349-4357. http://dx.doi.org/10.1021/ie800117aShen et al, Combust. Flame. 2008, 154(3), 489-506. http://dx.doi.org/10.1016/j.combustflame.2008.04.017

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Chemical looping at Southeast University,

Nanjing, China Numerical modelling and scale upSystem simulation: Aspen PlusMultiphase CFD modelling of Pressurized coal gasifierMultiphase CFD modelling of fuel reactor

Multiphase CFD

modelling of

air

reactor

Multiphase CFD modelling of interconnected fluidized beds

Shen, et al, Science in China Series E: Technological Sc, 2007 Xiang et al, Energy Fuels, 2008 Deng, et al, Energy Fuels, 2008

Deng et al, Int. J. Greenhouse Gas Control 2009

Publications: 8

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Major Challenges of coal fueled CLC Low operating temperature (~1000 oC)

Difficult to couple with advanced power generation system

Low efficiency

compared

with

traditional

combustion

Slow gasification rate, limiting stepPressurized Chemical Looping Combustion

Combined Cycle (PCLCCC) may be a solution. Higher coal combustion efficiency

Potential higher system efficiency for power generation, steam turbine + gas turbine

Lower cost of CO2 capture Wolf, J. et al, Fuel 2005

Garcia-Labiano et al, Energy Fuels 2006 Anthony, Ind. Eng. Chem. Res. 47 (6) (2008) 1747-1754.

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Pressurized CLCCC Existing established technologies

Pressurized Fluidized Bed Combustion Combined CycleR&D at Southeast University ~30 years

1MWt PFBC test facility (SEU-PFBC)15 MWe PFBC-CC pilot power plant

2MWt pressurized spout-fluid bed coal gasifier for2G PFBC-CC

References:

CFB technologySasol Gasification technologyFCC unit

M. Y. Zhang, in: Proceedings of the 12th International Conference on Fluidized Bed Combustion, 1993 Xiao, et al, Fuel 86 (10 11) (2007) 1631-1640.

J. C. van Dyk; et al, Int. J. Coal Geol. 65 (3-4) (2006) 243-253. Minchener, Fuel 84 (17) (2005) 2222-2235.

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Pressurized CLCCCDeveloping Chemical looping Technology

R&D at Southeast University, ~7 years

1 kWth Chemical-looping combustor 10 kWth Chemical-looping combustor 0.1 MWth PCLC combustor

References:10 kWth coal fueled CLC reactor in Chalmers, Sweden

50 kWth pressurized CLC combustor, KIER10 kWth CLC combustor, ICB/CSIC150 kWth CLC, VUTAlstom, TOTAL, IFP, etc.

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10 kWth Coal fueled CLC Combustor

Lyngfelt, et al., 2008 Shen, et al., 2009

Chalmers, Sweden Southeast, China

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Pressurized CLCCombined Cycle

Xiao et al, Energy Fuels, 2010, 24 (2), 14491463. http://dx.doi.org/10.1021/ef901070cMajor issue: Circulation of materials between two reactors, ref FCC

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Development of Oxygen Carrier Cost of Oxygen carrier

Deactivation by sulfur containing gases Thermal sintering

Inevitable Loss with coal ash, Environmental problem

Solutions 1: Reasonable cost, high stability materials

Synthetic high reactivity particles, NiO/NiAl2O4

Solutions 2: Low cost materials

Natural metal oxide, i.e. ilmenite (FeTiO3Fe2TiO5) Calcium based sulfate sulfide (CaSO4/CaS) cycle. Sulfur? Oxide scales (residual materials) from steel industry.

Leion, H. et al. Int. J. Greenhouse Gas Control 2008Chuang et al. Combust. Flame 2008

Song et al. Energy Fuels 2008

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Purpose Coal fueled PCLCCC system (Concept) Effect of Pressure on steam coal gasification Effect of Pressure on CLC of coal with iron ore Long term performance of oxygen carrier under

typical pressures

Application of Lowcost iron ore based oxygen carrier in Pressurized CLC

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Reactions StepsNormal coal fueled CLC concept (In situ gasification in the presence of oxygen carrier)(1) Coal pyrolysis and gasification:

Coal > Char + Pyrolysis gases and volatilesChar+H 2O+CO2 CO + H2 + CO2

(2) Oxidation of gases with oxygen carrier3Fe 2O3+H2=2Fe 3O4+H2O

3Fe 2O3+CO=2Fe3O4+CO2

(3) Regeneration of oxygen carrier: Air reactor4 Fe3O4 + O2= 6 Fe2O3

Fuelreactor

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Experimental setup

coal feeding unit, water/gas feeding and steam generator units, reactor, temperature control unit, back pressure regulator, steam cooler, filters, and gas analysis system.

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Materials

Proximate and Ultimate Analyses of Coal Samples

26.990.911.161.744.1664.7625.8742.8629.871.4XuzhouQ HSadNadO ad aH adC adAshFCadVadMad

Heatvalue

(MJ/kg)ultimate analysis (ad, wt%)

proximate analysis (ad,wt%)

sample

Chemical Analysis of the Natural Iron Ore Samples (CVRD, Brazil)

2.010.040.010.88004.1890.75Received

0000.910.000.004.3194.79Calcined

IgPSAl2O3MgOCaOSiO2Fe2O3Iron ore

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Operating Condition

1000 mL/min (S.D.)Oxidation gas flow rate

5% O2/N 2Oxidation1000 mL/mininert gas flow rateN2Inert gas1000 mL/min (S.D.)Total gas flow rate

87% H2O/N 2Gasification gas0.4 gFuel mass0.125 0.180 mmCoal particle sizeXuzhou Bituminous Coal, ChinaFuel

30 mmheight40 gMass0.09 0.125 mmOxygen carrier particle size 970

C

Reaction temperature0.1MPa 0.6MPaPressureCalcined CVRD iron ore, BrazilOxygen carrierOperation ParametersSpecies

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Characterization analysis

Received

Calcined1100 oC 6h, air

Phase:Hematite(Fe2O3)

Quartz (SiO2)

0 10 20 30 40 50 60 70 80 900

1000

20003000

4000

50000

2000

4000

6000

8000

Fresh, as received

B

B A

A

A

A A A A

A A

A

A A A

CD

C

2 (degree)

Calcined at 1100 oC, 6h

B AB B

B

A A A A A A

A

A A

A A

I n t e n s i

t y ( c o u n

t s )

A: Hematite, Fe2O

3

B: Quartz,. SiO2

C: Dolomite, CaMg(CO3)

2

D: Goethite, FeO(OH)

A

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Steam Coal Gasification Over Quartz

0.1 MPa 0.5 MPa

CO2 and H2 (Excess steam)Unsteady flow: pulse pump & pressure fluctuationPeaks emerge later at higher pressure 1>5 min

0 10 20 30 40 50 60 70 80 900

2

4

6

8

10

12

14

16

18

20

22

24

0 2 4 6 8 100

4

812

16

20

C o n c e n

t r a

t i o n

( % )

Time (min)

CO CO 2

CH 4 H2

C o n c e n

t r a t i o n

( % )

Time (min)

0 10 20 30 40 50 60 70 80 900

2

4

68

10

12

14

1618

20

22

0 2 4 6 8 100

4

812

16

20

C o n c e n

t r a

t i o n

( % )

Time (min)

CO CO 2 CH

4 H2

C o n c e n

t r a t i o n

( % )

Time (min)

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Gas Composition (dry basis)

Coal: Chinese Xuzhou coalMass: 0.4 g, 0.125 0.180 mmGasification agent: 87% H2O/N 2Flow rate:1000 mL/minT: 970 degrees

1.Thermodynamics

2. Kinetics:Higher [H

2O]

Diffusion within micropore

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Chemical looping combustion with iron ore

0.1 MPa reduction Oxidation

High CO2 obtained Volatiles: residence time short, not completely burnedCO release at later reduction period

Some CO2 release during oxidation

0 10 20 30 40 50 60 70 80 900

2

46

8

10

12

14

16

18

20

22

24

26

C o n c e n

t r a

t i o n

( % )

Time (min)

CO CO

2

CH4

H2

0 5 10 15 20 25 30 35 400

1

2

3

4

5

C o n c e n

t r a

t i o n

( % )

Time (min)

CO

CO 2 O

2

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0.5 MPa reduction and oxidation

Lower CH 4 and CO, higher CO 2 in later periodMore CO 2 release during oxidation

Pressure enhance unburned char combustion

0 10 20 30 40 50 60 70 80 90

02468

1012141618202224

26283032

C o n c e n

t r a

t i o n

( % )

Time (min)

CO CO

2

CH 4 H2

0 5 10 15 20 25 30 35 400

1

2

3

4

5

C o

n c e n

t r a

t i o n

( % )

Time (min)

CO CO 2 O

2

Chemical looping combustion with iron ore

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Gas composition and CO2 yield

CO2 increases from ~80% to ~92%CO decreases from 15% to ~5%CH4 fairly change but decrease at higher pressureH2 negligible and not detected at higher pressures

CO2 yield

0.1 0.2 0.3 0.4 0.5 0.60

10

20

30

40

5060

70

80

90

100

G a s c o m p o s i

t i o n (

V o

l . % )

Pressure (MPa)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

10

20

30

40

5060

70

80

90

100

Gasification over Quartz sand

C O

2 C a p

t u r e y i e

l d ( % )

Pressure (MPa)

Reduction of Iron ore

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Effect of Pressure on Carbon Conversion

Carbon Conversion is low: need long residence timeLower than gasification: Thermodynamics

Pressure suppresses pyrolysisbut enhance char gasification

dXc/dt~XcXc

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

10

2030

40

50

60

70

80

90

100

C a r b o n

C o n v e r s

i o n ( %

)

Pressure (MPa)

Gasification over Quartz Reduction period Oxidation period Total

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.00

0.05

0.10

0.15

0.20

0.25

0.1 MPa

0.3 MPa 0.4 MPa 0.6 MPa

C a r b o n

c o n v e r s

i o n r a

t e r C

( 1 / m i n )

Carbon conversion XC

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Char Gasification over oxygen carrier:

apparent kinetics

OH2

OH1

C

C

2

2

1

1

1

pk

pk dt

dX

X r C

+=

=

0.0 0.1 0.2 0.3 0.4 0.5 0.60.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

A p p a r e n

t g a s i

f i c a

t i o n r a

t e r

C ( 1 / m i n )

Partial pressure of steam pH2O (MPa)

Experimental Model prediction

A simple Langmuir Hinshelwood model excluding the effect of product inhibition provided a reasonable illustration of the effect of pressure on carbon conversion rate.However, excessive steam partial pressure results in negative effect.

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Effect of pressure on oxygen carrier Conversion

Oxidation reflects the extent of previous reductionIncreasing pressure, reduction conversion higher!Higher pressure has negative detrimental effect,

Thermodynamics: pressure of products (CO 2, H 2O) increase

0 10 20 30 40

0.980

0.982

0.984

0.986

0.988

0.990

0.992

0.994

0.996

0.998

1.000

1.002N2

M a s s - b a s e

d c o n v e r s

i o n

Time (min)

0.1 MPa 0.2 MPa 0.3 MPa 0.4 MPa 0.5 MPa 0.6 MPa

5% O 2/N2, 1000 mL/min

(a) 0.1 0.2 0.3 0.4 0.5 0.60.000.050.100.15

0.200.250.300.350.400.450.500.550.600.650.700.750.80

X

( - )

Pressure (MPa)

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0.1 MPa 0.5 MPaPurer CO 2 after 10 cycles

Activation during the redox cyclesNo appreciable deactivation

Effect of pressure on gas composition

long cycles

0 2 4 6 8 10 12 14 16 18 200

10

20

30

40

50

60

70

80

90

100

A c u m u l a

t i v e g a s c o m p o s i

t i o n

( v o

l . % )

Number of cycles

CO

CO 2 CH 4 H2

(a)0 2 4 6 8 10 12 14 16 18 20

0

20

40

60

80

100

A c u m u

l a t i v e g a s c o m p o s

i t i o n

( v o

l . % )

Number of cycles

CO CO

2

CH 4 H

2

(b)

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Effect of pressure on oxygen carrier Conversion:

Cyclic performance

0 2 4 6 8 10 12 14 16 18 200.0

0.2

0.4

0.6

0.8

1.0

OC conversion at 0.1 MPa OC conversion at 0.5 MPa

V a r i a t i o n o

f O C c o n v e r s

i o n

X ( -

)

Number of Cycles

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XRD analysis

0.1 MPa 0.5 MPa

H: hematite, M: magnetite, Q: Quartz, C: CaSi, possible

Activation with cyclesNo evident formation between iron and coal ash

0 10 20 30 40 50 60 70 80 90

Q HHH

H

HQHH

H Q

H

H H H

H

HH

H

M

2 de ree

(a) Calcined

MH

Q Q

HM

M

H

HM

Q

H

H

M

M H

M

(b) 0.1MPa-5red

C

HMHM MHMQ

H

Q

Q

H MH

QM

(c) 0.1MPa-10red

Q

QC

HMH

MHM

H

HM

H

M

M

(e) 0.1MPa-20red

(d) 0.1MPa-15red

H MQM C H

Q

Q H

H HQ

Q MM

H

MMH

Q

0 10 20 30 40 50 60 70 80 90

Q

Q HHH

H

HQHH

H Q

H

H H H

H

H H

H

M

2 (degree)

(a) Calcined

MQQ

CMH

Q

MM M

H

HM

Q

H

H

M

M

H

M

(b) 0.5MPa-5red

M MQ

C

M

H

MHM MHM

Q

H

Q

Q

H MH

MM

(c) 0.5MPa-10red

Q

MMQ Q

C

QH

MH

MHM

H

H MH

M

M

(e) 0.5MPa-20red

(d) 0.5MPa-15red

M MQ

CM

QH

H H

Q

H M MH

M

MHQ

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SEM Atmospheric Pressure

5red 10red 15red 20red

Particles maintain structureMore small grains formed after 10 cyclesSlight cracking after 20 cycles

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SEM Elevated pressure of 0.5 MPa

5red 10red 15red 20red

Particles maintain structure Activation after 5 cyclesSlight sintering and cracking after 20 cycles

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Pore size distribution

Maintain mesopore structureMore porous with cyclesSlight sintering at elevated pressure

1 10 100 10000.0

1.0x10 -52.0x10 -53.0x10 -54.0x10 -55.0x10 -56.0x10 -57.0x10 -58.0x10 -59.0x10 -51.0x10 -41.1x10 -4

P o r e

V o

l u m e

d V / d D

( c m

3 / g n m

)

Pore Diameter dP (nm)

Calcined 0.1MPa-5red 0.1MPa-10red 0.1MPa-15red 0.1MPa-20red

(a)

1 10 100 10000.0

1.0x10-5

2.0x10 -53.0x10 -54.0x10 -55.0x10 -56.0x10 -5

7.0x10 -58.0x10 -59.0x10 -51.0x10 -41.1x10 -4

P o r e

V o

l u m e

d V / d D

( c m

3 / g n m

)

Pore Diameter d P (nm)

Calcined 0.5MPa-5red 0.5MPa-10red 0.5MPa-15red 0.5MPa-20red

(b)

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ConclusionHigh CO2 Concentration could be obtained at relative high pressures;

The elevated pressure suppresses the pyrolysis of volatiles while it interestingly

enhances coal char gasification and reduction with iron ore in steam;

Excessive steam partial pressure may have a detrimental effect on the coal

gasification and the reduction of oxygen carrier by gasification gases;

Oxygen carrier maintains mesoporous structure after cycles; Crystalline Phases

do not change, no appreciable interaction of iron ore and coal ash;

Reactivity increased with cycles and stabilized after 510 cycles; No significant

deactivation within 20 cycles; Iron ore based oxygen carriers is promising

Limited experiments shows High temperature, high pressure CLC is promising

Accepted by Combust ion & Flame, Energy & Fuels

Xiao et al, Combusti on Flame, in press, http://dx.doi.org/10.1016/j.combustflame.2010.01.007Xiao et al, Energy Fuels, 2010, 24 (2), 14491463. http://dx.doi.org/10.1021/ef901070c

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Further work at SoutheastHigher pressures (20 30 atm) in PTGA

Longterm cycles of reduction and oxidation (50 100 cycles)

Modification of iron ore to reactive particles with active additives and inert support

Test of other low cost oxygen carriers, e.g. ilmenite

Sulfur and ash interaction with oxygen carriers

Kinetics study at elevated pressures

Multiphase CFD modelling of CLC process

Design of Novel CLC Reactors , 100 kWth PCLC combustor under

construction.

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CLC at Combustion groupUniversity of Cambridge

Dr. John Dennis

Dr. Stuart ScottTypical research topics related to Chemical looping:

Chemical looping combustion of solid fuels

Chemical looping Hydrogen from coal with steam iron process

Zero Emission Coal Alliance (ZECA) for H2 production and CO2

capture, Calcium looping sorbents

Kinetics and modelling of Chemical looping process

Multiphase DEM

CFD

modelling

of

Chemical

looping

process

A k l dg t

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Acknowledgements

National Natural Science Foundation of China (Grant Nos. 50606006, 90610016)

HighTech Research and Development Program of China (2009AA05Z312 )

National Basic Research Development Program of China (2010CB732206) Prof. Laihong Shen, SEU

Prof. Rui Xiao, SEU

Dr. John Dennis, University of Cambridge Dr. Henrik Leion, Chalmers University of Technology

Dr. H. J. Ryu, KIER

Many other researchers who have helped and are helping us on CLC.

China Scholarship Council

Conference Grant from Queens College and Shell Fund

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Thank you for your attention! Questions?

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Welcome to Southeast University!

Photos from SEU