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Densification of Biomass Feedstocks
Alan Doering, Agricultural Utilization Research Institute
Fueling the Future:
The Role of Woody and Agriculture Biomass for Energy Workshop
March 19, 2009
Morris
www.extension.umn.edu/agroforestry
Sponsored by:
University of Minnesota Extension, WesMin RC&D; Minnesota Department of
Natural Resources
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Densification of BiomassFeedstocks
Fueling the Future
Morris, MNMarch 19, 2009
Alan DoeringAgricultural Utilization Research Institute
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Goal
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Solid Fuel Focus Areas
Benefits
Market Potential
Densification Equipment Requirements
Fuel Characteristics
Pellet Quality Economics of Pellet Production
http://images.google.com/imgres?imgurl=http://www.comenalt.eu/prodotti/Light%2520pellets%5B1%5D.jpg&imgrefurl=http://www.comenalt.eu/prodotti/prodotti_eng.htm&h=520&w=650&sz=78&hl=en&start=20&um=1&usg=__lZPm3MQBC4-5I2tc0HRx_7sqens=&tbnid=npraxk0MVqte-M:&tbnh=110&tbnw=137&prev=/images?q=pellet&ndsp=20&um=1&hl=en&rls=SUNA,SUNA:2006-14,SUNA:en&sa=N8/8/2019 Dens if Ication
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Market Potential
Biomass Combined Heat & Power
BiomassMethanol
Biomass Ethanol (Cellulosic)
BiomassMethane
Biomass Pellet Fuels
Biomass Co-Firing
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Market Potentials
Pellet Fuel
Wood pellet stove/boiler
Corn stove/boiler
Multi-fuel stove/boiler
Outdoor furnace boiler
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Market Potential
CONCERNS:
Liability
Proper fuel for stove/furnace Ignition
Ash handling/storage
Emissions
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Why Biomass Densification?
Improved transportation
More efficient storage
Bales vs. loaves
Reduced biomass losses
Moisture reduction
Improvements in processingequipment
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Forms of Densification
Goal: To increase mass per unit ofvolume
- Grinding/particlereduction
- Compression
- Densification
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Equipment Requirements
Focus on particle size
Grinding capabilities
Industrial grinders
Hammer mills
Photos: Warren & Baerg Mfg.
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Processing Effect on Density
Effect of Grinding on Density Corn Stover:
Pre-grind on tub grinder (maximum 6 inch fiber lengths) 2.25 pounds/cubic foot
3/8 hole screen hammer mill grind 6.25 pounds/cubicfoot
Ryegrass: 38X18X16 bale 10.5 pounds/cubic foot
tub grinder (maximum 6 inch fiber lengths) 2.0
pounds/cubic foot 3/8 hole screen hammer mill grind 6.0 pounds/cubic foot
5/32 hole screen hammer mill grind 7.5 pounds/cubic foot
pellet using a 9:1 L/D pellet die 36.6 pounds/cubic foot
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Equipment Requirements
Pellet Mills
- Ring die - Flat die
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Equipment Requirements
Pellet Dies
- Ring die - Flat die
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Equipment Requirements
Pellet Dies
Compression Ratios (L/D ratio)
Diameter
Metals
Steel
Chrome
Alloy Abrasion resistant
Feed
Channel
Ring-die
PelletsKnife
Roll
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Equipment Requirements
Conditioning Capabilities
Most valuable resource
Steam vs. Water
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Sample Pellets &Characteristics
1
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Briquetting
1
AURI / University of Minnesota
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Pellet / BriquettingCharacteristics
1
AURI / University of Minnesota
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Pellet / BriquettingCharacteristics
1Form Product
Bulk Density
lbs/ft3Durability
%
PelletsCorn Stover 34 - 38 94 - 96
Switchgrass 33 - 36 73 - 87
BriquettesCorn Stover 26 - 30 67 - 90
Switchgrass 22 - 33 40 - 70
AURI / University of Minnesota
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Fuel Characteristics
Energy Content
Residual oil issues
Ash
Sulfur
Chlorides
Particulate Combustion Characteristics
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Fuel Characteristics
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Pellet Quality Density
40 pound per cubic foot
Dimension Length 1 max X or
5/16
Fines
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Pellet Quality
Pellet Durability PDI tumble tester Force gauge
Variables Fiber source Particle size Conditioning Feed rate
Die speed Die specifications
Glass transition of material (50 to 13oC)(Kaliyan and Morey, 2006a)
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Economics of PelletProduction
Material cost
Collection/transportation cost
Grinding/processing
Pelleting/cooling
Storage/bagging
Personnel/equipment
Fluctuating pellet fuel market
Debt service
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Economics of PelletProduction
Estimated pellet plant production cost/ton:
Assumption: corn stover cost $61/ton
2 ton/hr - $101.45/ton
4 ton/hr - $180.58/ton
8 ton/hr - $147.84/ton
Source: Feasibility Study Guide for an AgriculturalBiomass Pellet Company;www.auri.org
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Economics of PelletProduction
Fixed cost: $3 - $20 per ton based on throughput
Variable cost: $26.68 per ton
Raw Material cost: $46 per ton at 12% moisture
(including transportation into plant)
Cost per ton densified: $75.68 - $92.68 per ton
Model based on 3.3- 8 ton/hr switchgrass pelleting (King 1999)
*cost do not reflect mgmt., sales, billing, or final delivery
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Economics of PelletProduction
Drying Cost
Typically 1,400 2,000 Btu required perpound of moisture removed
63% moisture to 13% moisture = 50%
1,000 lbs water X 1,600 Btu= 1,600,000Btu
1.6 MMBtu X $9.00/MMBtu = $14.40
$28.80 / 2,000 pounds @13% moisture
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Pelleting Research
Pellet Mill Efficiencies
Economics of Pellet Production
Pellet Fuel Characterization
Pellet Quality
Combustion Characteristics
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Thank You!
Questions?