11

An Application of Dynamic Classifiers An Application of Dynamic Classifiers in Pulverized Coalin Pulverized Coal--Fired Boilers to Fired Boilers to Enhance Combustion Performance Enhance Combustion Performance

and reduce and reduce NONOxx, CO, and , CO, and Unburned Carbon Unburned Carbon

EmissionsEmissions

Electric Electric PowerPowerGeorgia World Congress CenterGeorgia World Congress CenterAtlanta, GAAtlanta, GAMay 3, 2006May 3, 2006

22

AuthorsAuthors

Kevin L. Dugdale, Loesche Energy Kevin L. Dugdale, Loesche Energy Systems, Ltd., UKSystems, Ltd., UK

David Miller, Power Technology, E.ONDavid Miller, Power Technology, E.ON--UK PLCUK PLC

Robert E. Sommerlad, Loesche Robert E. Sommerlad, Loesche America, Inc.America, Inc.

33

Preview of PresentationPreview of Presentation•• EC Large Combustion Plants DirectiveEC Large Combustion Plants Directive

-- NONOxx, SO, SO22, and Particulates by 2008, and Particulates by 2008•• Proposed Solution at RatcliffeProposed Solution at Ratcliffe--onon--Soar Power Soar Power

Station, E.ONStation, E.ON--UK PLCUK PLC-- Combustion Mods Combustion Mods –– Overfire Air and Overfire Air and Dynamic Classifiers Dynamic Classifiers

•• Four 500Four 500--MW Front Wall Fired BoilersMW Front Wall Fired Boilers•• Initial resultsInitial results

-- Dynamic Classifiers and impacts on Dynamic Classifiers and impacts on Unburned Carbon, NOUnburned Carbon, NOxx, and CO, and CO

•• Future PlansFuture Plans

44

Compliance Compliance ConsiderationsConsiderations

•• SOSO22 –– Wet scrubbers already in operationWet scrubbers already in operation•• Particulate Particulate –– Electrostatic precipitators Electrostatic precipitators

already in operation and fly ash soldalready in operation and fly ash sold•• NONOxx and LOI Considerations for 2008and LOI Considerations for 2008

–– ~35% Reduction required for ~35% Reduction required for compliance of 0.42 lb/MMBtucompliance of 0.42 lb/MMBtu

–– SCR and new LNBs considered and SCR and new LNBs considered and rejectedrejected

–– OFA selected for NOOFA selected for NOxx and DCs selected and DCs selected for LOIfor LOI

55

Installation ProgramInstallation Program

•• Dynamic classifiersDynamic classifiers-- Single DC installed in July 2003 and Single DC installed in July 2003 and testedtested-- Additional 6 DCs installed in Additional 6 DCs installed in Summer 2004 and testedSummer 2004 and tested-- Overfire Air System installed in and Overfire Air System installed in and commissioning in progresscommissioning in progress

66

Ratcliffe BoilersRatcliffe Boilers

•• Four 500Four 500--MW Babcock single MW Babcock single furnace, dry bottom, natural furnace, dry bottom, natural circulation boilercirculation boiler

•• Eight B&W 10E10 ring and ball mills Eight B&W 10E10 ring and ball mills normally using six mills for full loadnormally using six mills for full load

•• Two coal outlet pipes per mill with Two coal outlet pipes per mill with each split into 3 smaller pipes each each split into 3 smaller pipes each feeding a Babcock Mark 3 LNB for a feeding a Babcock Mark 3 LNB for a total of 48 burners in 4 rows of 12.total of 48 burners in 4 rows of 12.

77

Ratcliffe BoilerRatcliffe Boiler

88

Burner & Windbox Burner & Windbox PositioningPositioning

Burner Elevation

Wing Center Center Wing

73’ 6”(top)

G1-3 E4-6 E7-9 G10-12

66’O” B13-15 C16-18 C19-21 B22-24

52’ 0” A25-27 F28-30 F31-33 A34-36

44’ 6”(bottom)

H37-39 D40-42 D43-45 H46-48

99

DefinitionsDefinitions

•• ClassifierClassifier is a device that separates is a device that separates coarse and fine coal, allowing fine coal to coarse and fine coal, allowing fine coal to pass, while rejecting the coarse coal for pass, while rejecting the coarse coal for regrindingregrinding

•• Dynamic ClassifierDynamic Classifier is a device with an is a device with an inner rotating cage and outer stationary inner rotating cage and outer stationary vanes, which provides centrifugal and vanes, which provides centrifugal and impinging classificationimpinging classification

1010

Dynamic Classifier Dynamic Classifier CapabilitiesCapabilities

•• Enhance grinding performanceEnhance grinding performance•• Improve boiler performance (Efficiency and Improve boiler performance (Efficiency and

Slagging/Fouling)Slagging/Fouling)•• Reduce Unburned Carbon and increase fly ash Reduce Unburned Carbon and increase fly ash

salabilitysalability•• Reduce LOI, NOReduce LOI, NOxx, and CO , and CO

1111

EnhancementEnhancement

Enhancement of grinding performance is Enhancement of grinding performance is achieved by one of three ways:achieved by one of three ways:

•• Increasing fineness and thus reduce Increasing fineness and thus reduce coarse particles,coarse particles,

•• Increasing pulverizer capacity, orIncreasing pulverizer capacity, or•• Increasing both fineness and capacityIncreasing both fineness and capacity

1212

ImprovementsImprovements

•• Steeper fineness distribution slope angle Steeper fineness distribution slope angle (Rosin(Rosin--Rammler Plot)Rammler Plot)

•• Reduced amount of superfine and of Reduced amount of superfine and of coarse materialcoarse material

•• Reduced internal product recirculationReduced internal product recirculation•• Reduced overReduced over--grinding and reduced wear, grinding and reduced wear,

power absorption and mill vibrationpower absorption and mill vibration•• Reduced differential pressure across the Reduced differential pressure across the

mill and classifier potential for reduced mill and classifier potential for reduced mill gas flowmill gas flow

1313

FinenessFineness

Dynamic Classifiers can increase fineness Dynamic Classifiers can increase fineness and decrease coarse particles leading toand decrease coarse particles leading to

•• Better burnout (lower Unburned Carbon)Better burnout (lower Unburned Carbon)•• Reduced Slagging and FoulingReduced Slagging and Fouling•• Reduced Excess Air operation resulting inReduced Excess Air operation resulting in

-- Increased boiler efficiencyIncreased boiler efficiency-- Decrease in emissions Decrease in emissions –– NONOxx, CO, CO

1414

CapacityCapacity

Dynamic Classifiers can increase capacity Dynamic Classifiers can increase capacity while while maintainingmaintaining fineness fineness

•• Applicable to high volatile coals such as Applicable to high volatile coals such as PRB coals where burnout is not a problem PRB coals where burnout is not a problem but where lower heating value, higher ash but where lower heating value, higher ash and moisture content limit the coal and moisture content limit the coal throughputthroughput

•• Increase the blend ratio of PRB where Increase the blend ratio of PRB where higher HHV coals are blended to maintain higher HHV coals are blended to maintain capacitycapacity

1515

Fineness & CapacityFineness & Capacity

Dynamic Classifiers can increase both Dynamic Classifiers can increase both fineness and capacity, each to a lesser fineness and capacity, each to a lesser degree when each requires incremental degree when each requires incremental increasesincreases

•• Benefits accrue from both fineness and Benefits accrue from both fineness and capacitycapacity

•• Flexibility of operation allows maximum Flexibility of operation allows maximum application of benefits across load rangeapplication of benefits across load range

1616

Brief History & DevelopmentBrief History & Development

Classification technology R&D Classification technology R&D

underway since 1906, when the underway since 1906, when the

initial Loesche coal mill was initial Loesche coal mill was

patented.patented.

The experiences in grinding coal, The experiences in grinding coal,

petcoke, minerals, cement clinker, petcoke, minerals, cement clinker,

limestone, etc., contributed to the limestone, etc., contributed to the

successful development of the successful development of the

LSKS Dynamic Classifier.LSKS Dynamic Classifier.

1717

How does it work?How does it work?

The newly developed Loesche The newly developed Loesche

LSKS High Efficiency Dynamic LSKS High Efficiency Dynamic

Classifier improves the Classifier improves the

performance of vertical roller performance of vertical roller

mills.mills.

–– Redesigned air and product Redesigned air and product

flow velocitiesflow velocities

–– New flow characteristics New flow characteristics

within the classifierwithin the classifier

1818

Arrangement of Dynamic Classifier for Ratcliffe

1919

Dynamic Classifiers as Dynamic Classifiers as Retrofits for Existing MillsRetrofits for Existing Mills

2020

Comparison of Fineness Comparison of Fineness Ratcliffe Rosin Rammler Size Distribution - 36 t/h

10 100 1000

Sieve Size - micron

% P

assi

ng S

ieve

GuaranteeGuarantee, Mean R-R Slope = 50.8°Preconversion - Loesche Sieve ResultsPreconversion - Loesche Sieve Results, Mean R-R Slope = 31.7°Postconversion - Loesche Sieve ResultsPostconversion - Loesche Sieve Results, Mean R-R Slope = 52.7°

60

90

99

70

80

99.9

99.98

2121

Test MatrixTest Matrix

•• Load Load –– 510 to 520 MW510 to 520 MW•• Three different OThree different O22 levelslevels•• Three different DC speeds (100 rpm would Three different DC speeds (100 rpm would

be normal speed)be normal speed)-- 65 rpm (Static classifier ~75 rpm)65 rpm (Static classifier ~75 rpm)-- 90 rpm90 rpm-- 110 rpm110 rpm

•• Six mills in service Six mills in service –– 5 with DCs & 1 with 5 with DCs & 1 with SCSC

2222

DC Speed vs LOIDC Speed vs LOI

R2 = 0.8894

R2 = 0.9944

R2 = 0.246

0.00

2.00

4.00

6.00

8.00

10.00

12.00

5.00 5.20 5.40 5.60 5.80 6.00 6.20 6.40 6.60 6.80

Oxygen % (Stack)

LOI (

%)

110 RPM - LOI (%)

90 RPM - LOI (%)

65 RPM - LOI (%)

Expon. (110 RPM - LOI (%))

Expon. (90 RPM - LOI (%))

Expon. (65 RPM - LOI (%))

2323

DC Speed vs NODC Speed vs NOxx

R2 = 0.9573

R2 = 0.9528

R2 = 0.9994

0.45

0.50

0.55

0.60

0.65

0.70

0.75

5.00 5.20 5.40 5.60 5.80 6.00 6.20 6.40 6.60

Oxygen % (Stack)

NO

x (lb

/106 B

tu) 110 RPM - NOx

90 RPM -NOx

65 RPM - NOx

Linear (65 RPM - NOx)

Linear (90 RPM -NOx)

Linear (110 RPM - NOx)

2424

DC Speed vs CODC Speed vs CO

R2 = 0.9986

R2 = 0.9999

R2 = 0.976

0.00

200.00

400.00

600.00

800.00

1000.00

1200.00

5.00 5.20 5.40 5.60 5.80 6.00 6.20 6.40 6.60

Oxygen % (Stack)

CO

(ppm

)

110 RPM - CO (ppm)

90 RPM - CO (ppm)

65 RPM - CO (ppm)

Expon. (110 RPM - CO (ppm))

Expon. (90 RPM - CO (ppm))

Expon. (65 RPM - CO (ppm))

2525

ResultsResults

•• LOI reduced by 61%LOI reduced by 61%•• NONOxx reduced by 15%reduced by 15%•• Window of operation before Window of operation before

excessive CO produced increasedexcessive CO produced increased•• Operation at lower OOperation at lower O22 level possible level possible

while holding CO and potential for while holding CO and potential for further NOfurther NOx x reduction of about 20%reduction of about 20%

2626

Future PlansFuture Plans

•• Overfire Air System with booster Overfire Air System with booster fansfans-- Installed and in commissioningInstalled and in commissioning-- Testing in Summer 2006Testing in Summer 2006-- Install DCs and OFA on other unitsInstall DCs and OFA on other units

•• Dynamic Classifiers installed on other Dynamic Classifiers installed on other similar boilers in the UK including similar boilers in the UK including ball mills and arch furnace boilersball mills and arch furnace boilers