evaluation of oxyevaluation of oxy-coal combustioncoal

Evaluation Of Oxy coal CombustionEvaluation Of Oxy-coal Combustion at a 30MWth Pilot

1st International Oxyfuel Combustion Conference7th- 11th September 2009, Cottbus, Germany

D.K. McDonald Technical Fellow

Co-Authors:

H Farzan, DK McDonald, Babcock & WilcoxR. Varagani, N. Docquier, N. Perrin, Air Liquide

© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.

Commercialization PathwayPlant size (MWe)

500Integration

Study

Engrg.Study

ASU Effi i

30 MWth

150

Eng Studies

100 MWe DemonstrationASU EfficiencyOptimization

30 MWth CEDF demo

10Lacq Oxy-gas burners & CPU Test, BWRC

Component Test

SBS – I Pilot tests

1

SBS- II Callide CPU

Component Test

2003 2005 2007 20132009 2011 2015

© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .2

Commercialization Pathway

Black Hills Oxy-coal Demonstration Project


30 MWth Oxy-Coal Testing

• Built in 1994 with support from DOE and OCDO

• 100 Million Btu/hr

30 MWth Test Facility located in Alliance, Ohio

(30 MWth) input with coal

CEDF OxygenSupply System

Main Control Room

© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .4© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .4

30 MWth Oxy-Coal TestingSec O2

Gray = Existing Blue = New

Total Sec OxidantInfiltrated AirDry

Sta

ck

Sec Air

CESPO2 Mixer

CEMS SO

m

ss

ck

m

Trim Heater

Infiltrated AiryScrubber

OF OxidantHeater

ID Fan

CEMS SO2, O2, NOx (Dry)

CO, CO2, SO2, O2, TWB,

SO2, CO2

(Dry)

m

Sec Oxidant to Burner C

onve

ctio

n Pa

s

Furn

ace

O2

(Wet) lue

Gas

to S

tac

Sec Air Fan WFGD C l

Wind Box

NOx (Dry) TDB, P

T, PO2

(Wet) O2

(Wet)m

mm

Lance O2

Primary Oxidant

C

PA

F

RFG

to Boil

Sec RFG

Sec Air

Pulv Air

Raw Coal PCPCO2 Mixer

Prim Air Fan CoolerRaw Coal

Raw Coal FeederPri RFG

O

m

mm

mTWB,

TDB, P

Heater

lerWaste

Prim AirBH

m

Qualitative flow indicationQuantitative flow measurementAlternate flow measurementClosed for indirect feed operationClosed for direct feed operation

Pulverizer Air FanMill

PC Feeder

Pri O2

O2

(Wet) m

Mill Air Heater Pulv Air

m

m

T, P

mm


Combustion Performance

As-Received Coal Analyses

Coals Tested

Bituminous Sub-Bituminous LigniteMahoning #7 Black Thunder SaskPower

Air Dry Loss Moisture (%) 0 2.56 3.85Proximate Analysis (%)

3 34 28 03 32 92Moisture 3.34 28.03 32.92Ash 7.48 4.17 8.09Volatile Matter 37.02 31.83 28.31Fixed Carbon 52.16 35.96 30.69Ulti t A l i (%)Ultimate Analysis (%)Carbon 76.28 49.97 41.85Hydrogen 5.16 3.69 2.86Nitrogen 1.58 0.55 0.3

1 52 0 25 0 34Sulfur 1.52 0.25 0.34Oxygen 4.64 13.33 13.65Calorific Value, Btu/lb 13261 8815 7142


Pulverizer Performance

• At same parameters, maintained similar performance with oxy or air firing (operated below full capacity)

• Some reduction in PF/PC may be possible

3.00

2.002.252.502.75 Air Blown Combustion

Oxy Combustion

Coa

l Flo

w

0 751.001.251.501.75

PA/P

C

ary

Flow

/C

0.000.250.500.75

PRB at 5 T/hr Lignite at 6 T/hr

Prim

a


Combustion PerformanceAdjustableSecondary AdjustableSecondary

3 Burners TestedAdjustable Swirl Vanes

Secondary OxidantExtraction

Oxidant to Furnace

O2 Lance

Adjustable Swirl Vanes

Secondary OxidantExtraction

Oxidant to Furnace

O2 Lance

Outer ZoneAdjustable

Vane

Stationary Vane

Sliding Air Damper

Air MeasuringPitot Grid

PC and Primary OxidantPC and Primary Oxidant

ConicalDiffuser

Inner ZoneAdjustable

Vane

PAX-XCL PRB and lignite

Pulverized CoalandPrimary Air Inlet

DRB-XCL

Enhanced Ignition PRB

DRB XCL Bituminous


Combustion Performance

70

80

% NOx Reduction Air vs. Oxy Firing• Significant NOx reduction verified

• CO ll li htl l ith

50

60

70

duct

ion,

• CO normally slightly lower with oxycombustion

• LOI similar for air or oxy

20

30

40

NO

x R

ed%

• Attached stable flames with all fuels (sensitive to moisture)

0

10

Bituminous PRB LigniteDRB-XCL Burner EI Burner PAX-XCL Burner


Heat Transfer Performance

EI BurnerAir Firing

Sub-bituminousSteam injection in secondary initiated

Oxy FiringAir Firing

Oxy FiringWarm recycleCold recycle

Oxy Firing

Effects on Heat Transfer

• FEGT was lower• H t fl l ith b ti• Heat fluxes were lower with oxy-combustion

• Density and emissivity impact of high CO2• Moisture impact on flame temperature


Wet Scrubber/Cooler Performance

SO2

• R l ti f h d• Relative performance showed oxy-firing SO2 removal 5 % to 10 % better than air-firing removal (91.2% to 92 % SO removal)SO2 removal)

2.50

Bituminous Coal2

2.00

Bituminous Coal

1

2

mov

al (N

TU)

CEDF WFGD Tower Installation1.00

1.50

1SO2R

em


Wet Scrubber/Cooler Performance

SO3

• Measured SO3 (bituminous coal) across the wet scrubber doubled from air to oxy firing on a heat input basis (but data is not conclusive)basis (but data is not conclusive)

• SO3 formation may be higher with oxy-combustion Concentration inherently higher due to removal of N2 Concentration inherently higher due to removal of N2 Acid dew point is higher due to higher concentration SO3 removal is advisable Condensation should be preventedp


Wet Scrubber/Cooler PerformanceMoisture

• Moisture in the flue gas is high especially for high moisture

25

• Moisture in the flue gas is high, especially for high moisture coal (15-35% by volume depending on coal)

• Removal benefits

15

20

25

Moi

stur

e, %

Removal benefits Improved combustion

(increases flame temperature)

5

10

Rec

ycle

Gas

Mp ) Improved coal drying and

conveying Must be removed before

0100 110 120 130 140 150

WFGD Outlet Temprature, F

CPU outlet


ESP Performance

100

120

60

80

rent

(maD

C)

Air CombustionOxy-combustion

20

40Fiel

d C

urr

00 10 20 30 40 50 60 70

Field Voltage (KVDC)

ESP Field 1 Voltage‐Current OperatingESP Field 1 Voltage Current Operating Characteristic with the PRB Coal


Mercury

Speciation

• Hg measured by on-line analyzerHg measured by on-line analyzer• Hg data taken when firing lignite• Hg in flue gas (air firing) was ≈ 13.5µg/m3

• Hg concentration in flue gas increase in oxy modeHg concentration in flue gas increase in oxy mode corresponded to removal of N2. • Oxidized (ionic) Hg increased from 25% to 30% Increases removal (less elemental Hg)

• Oxidized Hg removed in WFGD

CONCLUSIONS:

1. Hg oxidation may improve with oxycombustion2. Hg removal is expected to be the same as for air firing


Air InfiltrationImpact of Air Infiltration

• Increased gas volume

• CEDF air infiltration ≈ 10% (vol) CEDF not designed to minimize CO2 concentration 60%-65% (vol)Increased gas volume

Increases ID fan CPU power

Decreases ID fan and CPU 100

• Commercial unit infiltration ≈ 5% (vol) CO2 concentration 80%-85% (vol)

capacity Could limit unit load Reduces fuel efficiency 80

90

ntra

tion

ASPEN Simulation of CEDFCEDF Data with Lignite

• Increased NOx60

70

CO

2C

once

n

500 2 4 6 8 10

Infiltrated Air (%)


Oxygen Mixing

• Oxygen was well mixed Higher concentrations were

kept at the center of flues

Floxinator TM

kept at the center of flues Variation between highest and

lowest concentrations was lowS

S

15% - 16%14% - 15%

13% - 14%

S

S

S

16% - 17%

S

S


1 2 3 4 5 6S

Process Controls50 00050 000

35,000

40,000

45,000

50,000

/hr)

Secondary RFG

Secondary Air

35,000

40,000

45,000

50,000

)

Secondary RFG

Secondary Air Air to Oxy Oxy to Air

15,000

20,000

25,000

30,000

Flow

Rat

e (lb

/

Primary RFG

15,000

20,000

25,000

30,000

Flow

(lb/

hr)

Primary RFGPrimary Air

0

5,000

10,000Total Oxygen

Primary Air0

5,000

10,000Total Oxygen

Convection Pass CO2


Conclusions1. The transition from air-firing to oxy-firing and back was smooth without major

flow or pressure upsets in the boiler.

2. Pulverizer performance was not negatively impacted by higher flue gas density and moisture content during oxy-firing operation.

3 Flames were attached with all three coals tested and the flame stability3. Flames were attached with all three coals tested and the flame stability depended on the recycle gas moisture and coal moisture. Moisture levels well in excess of 35% in the secondary recycle gas were tested.

4 E i i h t i ti f fi i f bl i fi i f ll th4. Emission characteristics of oxy-firing were favorable over air-firing for all three coals tested. NOx reduction ranged from 40% to 70% during oxy-firing and CO and UBC were similar.

5. Furnace exit gas temperature (FEGT), flame temperature and furnace heat fluxes slightly decreased with oxy-firing and was sensitive to moisture and recycle gas flow rate.


Conclusions

6. B&W’s patented moisture control concept worked well in reducing moisture.

7 Oxy SO removal was 5% 10% better than air firing removal7. Oxy SO2 removal was 5%-10% better than air-firing removal.

8. Higher SO3 concentration with oxy-firing requires careful consideration and/or removal.

9. ESP particulate emissions with oxy-firing are essentially the same as for air-firing but slightly higher power is required due to a lower volumetric flow and increased specific particle loadingand increased specific particle loading.

10.Mercury concentration significantly increased due to removal of nitrogen but oxidation also increased. Since the same mass of Hg must be removed

ith i fi i th hi h t ti d i i ti h ldwith air or oxy firing, the higher concentration and ionic portion should improve removal in the environmentalequipment.


Thank You!

© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.© 2009 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .21© 2008 The Babcock & Wilcox Company. All rights reserved. .21

evaluation of oxyevaluation of oxy-coal combustioncoal

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