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Black Pellets: A Fuel for Power
Choosing Pellet Fuel to Cut Costs and Improve Operations
Nordic Baltic BioenergyBjörn Forsberg
RigaApril 14-15, 2015
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Nordic Baltic Bioenergy
How Black pellets are made
Selma: construction status, conversion scope, pellet transport & storage at port
Safety in Operations: Advantages of Black vs. white
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Zilkha Black® Pellets—A Real Option for Power ProducersAdvanced wood pellet that is:• Grindable• Low-dust• Water-resistant• Stored outside• High bulk density• Can be burned direct in
existing coal power plants • Co-fired up to 100%• Reduced capital required
Certified sustainably harvested
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Zilkha Black® PelletTechnology
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What Is a Black Pellet?
Zilkha Black® pellets are thermally conditioned biomass pellets 100% wood with no natural or artificial additives. NONE.
The thermal conditioning process is well known. NOT TORREFACTION
The pellet itself has mechanical and physical properties which are highly desirable for use in power plants to replace coal
Specifically, Black pellets are harder than white pellets because when pelletized, the abundant free lignin melts and acts as a water resistant glue
As a result Black pellets have reduced fines and very low dust compared to conventional white pellets. Not zero. But greatly reduced.
Black pellets can be shipped, received, stored, conveyed, and milled just like coal
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Zilkha Technology at a Glance
Manufacturing of Zilkha Black® Pellets is similar to the production of standard white pellets, with the addition of our patented thermal conditioning step.
IntakeSawdust, wood chips, and first
thinning
DryingReduce moisture content from
ambient (~50%)to 6-10%
Proprietary Patented Zilkha
Thermal Conditioning
Milling & Pelletizing
Feedstock is resized then passed through dies to create
Zilkha Black® pellets
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Making Black Pellets
Wood is chipped, sealed in a pressure vessel, and pressured with steam After “cooking” briefly (5-15 min) the pressure is quickly released and the steam
pressure “blows” the material into a receiving tank The conditioned material moves by conveyor to a standard pellet mill
Wood is composed of cellulose, hemicellulose, and lignin (~1/3-1/3-1/3) The thermal conditioning frees the lignin Lignin is a natural waterproof glue which melts at ~125+ °C, a temperature which is
reached inside the pellet die Results in a tight, hard pellet bonded together with a natural, waterproof glue No additives of any kind are used.
HOW:
KEY:
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Thermal Conditioning Before and After
Hammer-milled wood particles before thermal conditioning
The result AFTER thermal conditioning: the wood is more easily pelletized and is “glued” using abundant lignin
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End Result: A Direct Replacement for Coal
How do Black pellets stack up vs. white pellets ?
Harder and more brittle Fewer fines Less dust Water resistant
Just Like Coal
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Selma Alabama USA, 275 000 tpy
Selma Plant Startup
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Selma Plant Undergoing Commissioning & Startup
Zilkha Thermal Conditioning
Island
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First Black Pellets from Selma
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Selma Rebuild = General Improvements + Black Conversion
General improvements: New chip yard BRUKS (scale, truck dump, radial stacker, chip reclaim, scalper,
green chip resizing, new green feed delivery conveyors) Dryer island (MEC dryers reconditioned, new powder fired hot gas generation
system from WTS powder burners) Pelleting (reconditioned Andritz pellet machines, aspiration, pellet conveyors) Out loading (more storage, de-dusting, truck loading station)
White to Black conversion: Black pellet island (thermal conditioning and blow tank) Post conditioning (dry grinding, delivery conveyors)
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Conversion to Black—Reroute Through Conditioning
ChipyardDryers
Pelleting
Coolers
Outloading
Resizing
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Adding Black Unit Achieves Conversion from White
Chipyard
Reroute Through
Thermal Conditioning
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New Thermal Conditioning Island
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Pellets Are Trucked from Selma to Mobile, Alabama
280 km from
Selma to Mobile
25 Metric Tonnes per
Truck
36 Trucks per Day
216 Trucks per Week
936 Trucks per Month
11 Hours of Unloading per Day / 6 Days per
Week
End-Dump Wood Chip
Trailer
Truck Loading System
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Terminal Operations in Mobile
Pellets received using truck dump dedicated to
Black pellets
Pellets stored in hopper
barges
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Barges Fleeted Prior to Mid-Streaming Onto Ships
Barge Fleeting
Area
Barge Fleeting
Area
Mid-streamShip Loading
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Reduce White Pellet Safety Risk by using Black Pellets
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White Pellet Risk Factors
Key areas where Black pellets have a storage and handling advantage:
Self Heating Off-Gassing Dust
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Dust = very real explosion risk
Explosion mitigation takes capital beyond that required to handle coal
Off-gassing of CO, CO2, and CH4 require venting during storage and transport
Pellet pile self heating can lead to fires
White Pellets Taught Safety Lessons
Source: Staffan Melin. Safety in Handling Wood Pellets. 2008.
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University of Nottingham: Self Heating Not Present
University of Nottingham 2 thermally conditioned
piles and 2 wood chip piles 6 month storage test
Conclusion: Thermally conditioned
Black pellets, both indoor and outdoor, saw no distinct increase in temperature. No evidence of self-heating.
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UBC: Dangerous Gas Emissions Greatly Reduced
Less methane:
WHITE
BLACK
Less carbon monoxide:
WHITE
BLACK
More oxygen:
BLACK
WHITE
Zilkha Black® pellets tested at UBC were far less reactive than white pellets. Black pellets were found to have significantly reduced oxygen depletion
Oxygen depletion is a significant operational issue. Extra workers and other special safety restrictions are required for workers entering white pellet storage areas
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Minimal Dust from Conveyor Drop
Pellets drop several feet from final conveyor discharge at Zilkha’s Crockett plant
No visible dust
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Parking Lot Drop Test Shows Minimal Dust
Pellets stored outside in Europe
Urban location sensitive to dust
Pellets were exposed to a few days of rain
Operator test was looking for dust
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Black Pellets are Water-Resistant which Means …
Zilkha Black® Pellets
compared to conventional white pellets
after brief exposure to
water
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Black Pellets Load Like Coal and No Problem with Rain
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Black Pellets Can Use Established Dust Suppression Technology
Water is a very effective, widely used method of dust suppression for coal. The same methods can be used for Black pellets. Just like coal.
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Water Spray on Coal at Transfer Points & Hoppers
Transfer Points
Hoppers
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Zilkha Black Pellet Outdoor Storage Experience
Canada Sweden
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Zilkha Black Pellet Outdoor Storage Experience
Coal
Black Pellets
Denmark France
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Summary Zilkha’s Selma plant construction and commissioning complete—in startup Selma proves conversion of white pellet plants to make Black pellets is
straightforward White conversions to Black will accelerate Black pellet availability The combination of conversions and new build Black plants provide geographic
diversity as well as multiple suppliers Cooperative “backup” relationships and agreements will form a robust supply
system Zilkha has an active license program for new producers as well as conversion from
white to Black Zilkha Black pellets offer a low capital solution for power producers Black pellets handle, store, and can be managed just like coal Black pellets are a lower risk, cost effective option for power plant owners
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