Co-firing Coal and Oat HullsCo-firing Coal and Oat Hullsat theat the

University of MinnesotaUniversity of MinnesotaVIII International Oat Conference

June 28 – July 2, 2008

Minneapolis, MN

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VIII International Oat Conference June 28 – July 2, 2008

Foster Wheeler Twin Cities, Inc. Foster Wheeler Twin Cities, Inc. University of Minnesota University of Minnesota

• Management, Operation and Maintenance Agreement (MOMA) - July 1992

• Construction Agreement - July 1992

• New Package Boilers, FW CCFB and Turbine Generator at UM SE Plant Completed - 2000

• Cost Reimbursable Contract (MOMA II) - May 2004• Fixed Fee• Performance Fee

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota - SE Heating PlantUniversity of Minnesota - SE Heating PlantSteam Source for Minneapolis CampusSteam Source for Minneapolis Campus

(On Mississippi River at St. Anthony Falls)(On Mississippi River at St. Anthony Falls)

VIII International Oat Conference June 28 – July 2, 2008

National Register of Historic PlacesNational Register of Historic PlacesTwin City Rapid Transit Company Steam Power Plant -1903Twin City Rapid Transit Company Steam Power Plant -1903

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota University of Minnesota Foster Wheeler Compact Circulating Fluidized BedFoster Wheeler Compact Circulating Fluidized Bed

FW CCFB

• 200,000 lbs/hr

• 930 psig, 900 oF

• 15 tons/hr, 8,750 Btu/lb subbituminous coal

• Boiler and baghouse inside building

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota University of Minnesota Reasons for Biomass UtilizationReasons for Biomass Utilization

• Minnesota Pollution Control Agency Permit limits annual coal and oil use to 30% of fuel mix on a Btu basis.

• Balance of permitted fuel mix is natural gas, wood and oat hulls.

• Wood and oat hulls are less expensive than natural gas.

• University is a member of the Chicago Climate Exchange and is committed to reduction in net CO2 emissions.

VIII International Oat Conference June 28 – July 2, 2008

Limitations on Biomass UtilizationLimitations on Biomass Utilization

• University biomass limited by permit to wood and oat hulls.

• New types of biomass require a permit amendment which may take years to obtain.

• Contractual commitments from biomass suppliers difficult to obtain due to competition for materials.

• Biomass utilization has major material handling issues.

• University solid fuel systems not designed to handle wood and oat hulls.

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota Biomass Utilization IssuesUniversity of Minnesota Biomass Utilization Issues

• Acquisition and Accounting

• Material properties affecting transporting, flow and combustion

• Dust control

• Spontaneous combustion

• Odor issues

VIII International Oat Conference June 28 – July 2, 2008

Acquisition and Accounting IssuesAcquisition and Accounting Issues

• Scheduling coordination with coal deliveries.• Coal delivered by rail (20 – 30 railcars)• Oat hulls by truck, 50 - 60 trucks for each coal delivery

• Limited storage for coal and oat hulls

• Accurate fuel inventory is difficult.

• Large numbers of trucks due to low bulk density (100’s of weigh tickets)

VIII International Oat Conference June 28 – July 2, 2008

Biomass and Mixed Fuel Bulk DensitiesBiomass and Mixed Fuel Bulk Densities(UM solid fuel systems designed for volumetric flow)(UM solid fuel systems designed for volumetric flow)

Material Properties

Product Bulk Density (lbs/cu. ft.)

Oat Hulls (compaction varies) 11 – 21

Oat Hull Pellets 36

Wood 12

Coal/Oat Hull Mix 20 – 40

Subbituminous Coal 54

VIII International Oat Conference June 28 – July 2, 2008

Coal and Oat Hull Fuel AnalysisCoal and Oat Hull Fuel Analysis(Concern is Chlorine due to HAP’s Emission Limits)(Concern is Chlorine due to HAP’s Emission Limits)

HAP’s = Hazardous Air PollutantsHAP’s = Hazardous Air Pollutants

Fuel Analysis: Subbituminous Coal and Oat Hulls

Property (as received) Subbituminous Coal Oat Hulls

Moisture % 27.49 8.78

Carbon % 51.35 42.49

Hydrogen % 2.9 4.66

Nitrogen % 0.68 0.83

Sulfur % 0.23 0.12

Ash % 4.79 5.19

Oxygen % 12.56 37.93

Chlorine % <0.01 0.1

HHV (Btu/lb) 8,748 7,091

VIII International Oat Conference June 28 – July 2, 2008

Primary Form of Oat Hulls Delivered to UniversityPrimary Form of Oat Hulls Delivered to University

VIII International Oat Conference June 28 – July 2, 2008

Alternate Form of Oat Hulls Delivered to UMAlternate Form of Oat Hulls Delivered to UM

VIII International Oat Conference June 28 – July 2, 2008

Oat Hull PelletsOat Hull Pellets(Delivered by Rail from Canada)(Delivered by Rail from Canada)

VIII International Oat Conference June 28 – July 2, 2008

Oat Hull Pellets After Outside StorageOat Hull Pellets After Outside Storage

VIII International Oat Conference June 28 – July 2, 2008

University Coal Unloading and Storage BuildingUniversity Coal Unloading and Storage Building(All solid fuel delivered to this site)(All solid fuel delivered to this site)

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota Coal Storage BuildingUniversity of Minnesota Coal Storage Building(Coal depth 12 feet where person is standing)(Coal depth 12 feet where person is standing)

VIII International Oat Conference June 28 – July 2, 2008

Unloading Oat HullsUnloading Oat Hulls(All deliveries using walking floor trucks)(All deliveries using walking floor trucks)

VIII International Oat Conference June 28 – July 2, 2008

Mixing Coal and Oat HullsMixing Coal and Oat Hulls(Mixing two volumes of oat hulls to one of coal)(Mixing two volumes of oat hulls to one of coal)

VIII International Oat Conference June 28 – July 2, 2008

Mixing Coal and Oat HullsMixing Coal and Oat Hulls(note oat hull dust) (note oat hull dust)

VIII International Oat Conference June 28 – July 2, 2008

Mixing Coal and Oat HullsMixing Coal and Oat Hulls

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota Tunnel ConveyingUniversity of Minnesota Tunnel Conveying(Note dust hood near top of picture and sprinkler heads) (Note dust hood near top of picture and sprinkler heads)

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota SE Plant Storage BunkerUniversity of Minnesota SE Plant Storage Bunker(Telescoping chute for dust control)(Telescoping chute for dust control)

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota SE Plant Coal Storage BunkerUniversity of Minnesota SE Plant Coal Storage Bunker(30% Oat Hull, 70% Coal Mix)(30% Oat Hull, 70% Coal Mix)

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota SE Plant Bunker University of Minnesota SE Plant Bunker Temperature 6 Inches Below SurfaceTemperature 6 Inches Below Surface

(white material is snow, odor of material present)(white material is snow, odor of material present)

VIII International Oat Conference June 28 – July 2, 2008

University of Minnesota SE Plant Bunker after Heavy Snowfall University of Minnesota SE Plant Bunker after Heavy Snowfall (snow melted off surface from heat in bunker)(snow melted off surface from heat in bunker)

(odor of decomposing oat hulls present)(odor of decomposing oat hulls present)

VIII International Oat Conference June 28 – July 2, 2008

Modes of University CCFB Boiler OperationModes of University CCFB Boiler Operation

• Boiler base loaded with mix of coal/oat hulls/wood

• Boiler load following on gas with fixed amount of coal/oat hulls/wood

• Boiler load following on gas with fixed amount of oat hull pellets

Daily Campus Steam Load 4/23/07

80000

90000

100000

110000

120000

130000

1

lbs/hr

VIII International Oat Conference June 28 – July 2, 2008

Fuel Mixture Effect on University CCFB Boiler OperationFuel Mixture Effect on University CCFB Boiler Operation

• Rat-holing constant problem in CCFB silos

• Spontaneous combustion in silo wall buildup

• Reduction in NOx Emissions (> 15%)

• Flyash reinjection problems reduced due to a lower density flyash

VIII International Oat Conference June 28 – July 2, 2008

Effect on University of Minnesota CCFB Boiler OperationEffect on University of Minnesota CCFB Boiler Operation(boiler slag formations due to coal/oat/wood mixture)(boiler slag formations due to coal/oat/wood mixture)