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Solid biofuels from torrefied biomass
Production of Solid Sustainable Energy Carriers from Biomass by Means of Torrefaction – The SECTOR project
Wolfgang Stelte, Ph.D.
Center for Biomass and Biorefinery
Danish Technological Institute – DTI
Danish Technological Institute -DTI
Private, self-owned and not-for-profit institution
Development and dissemination of research- and technologically-based knowledge for the Danish and international business sectors
Center for Biomass & Biorefinery
Biomass logistics and storage : Safety, cost reduction, supply chain modeling and optimization
Characterization: Chemical analysis, heating value, combustion properties, ash content, impurities
Pre-treatment: Mechanical, thermal, enzymatic pre-treatment of biomass
High value side streams: Materials, nutrients, food, feed, fertilizer
Liquid, solid, gaseous biofuels
Industry consulting
R&D Projects with industry and universities
Pellet related activities at DTI
Pelletizing process: Laboratory and pilot scale facilities
Lab scale: Single pellet press - Parameter screening and optimization, friction and quality test (100 g material) Bench scale: Kahl press, flat die (50 kg/h) Pilot and production scale facilities: Andritz presses (250-2000 kg/h)
Pellet related activities at DTI
Storage and handling and safety of pellets
Research activities and consulting in the following areas:
Monitoring of critical parameters: Risk evaluation, hazard reduction and fire prevention
Self heating, oxygen depletion and off-gassing during transport & storage
Safety in silos and during shipping, ATEX, dust Prevention
Pellet related activities at DTI
Standardization and quality analysis
Biomass Analysis: Ash, heavy metals, sulfur, chlorine, C, H, N, Ash melting and slagging, etc. Pellet quality: Mechanical durability, heating value, density, etc. Consulting pellet producers: Standardization and certification
Offering commercial analysis Wide range of standard methods (EN/ISO) Development of new test methods
Production of Solid Sustainable Energy Carriers from Biomass by Means of Torrefaction – SECTOR
Collaborative project financed by European Commission
Project start: 01.01.2012
Duration: 42 months
Total budget: 10 Mio. Euro
Participants: 21 from 9 EU-countries
Coordinator: DBFZ
SECTOR Project
SECTOR Project SECTOR Project
Pellets from torrefied biomass
Advantages of torrefaction and pelletization
Torrefaction is a mild roasting of biomass in an inert atmosphere
Removal of water and volatiles from biomass Increased heating value
Increased C/O ratio: better combustion / fuel properties
Fibers are converted into a brittle material Easy to grind (coal mill)
Dry product with hydrophobic characteristics
Biomass with coal like properties
Pelletization
Increase density and reduce dust formation
Lowering transportation and handling costs
Standardized size and automated feeding
Pellets from torrefied biomass
Possible problems when pelletizing torrefied biomass
High friction in press channel
High energy uptake of pellet mill up to 150 kWh/t (usually 50-60 kWh/t for wood pellets)
Heat generation in pellet mill (risk of fire / dust explosion)
Lower capacity
More wear on the pellet mill parts
Pellet quality
Durability
Self heating
Density
Hydrophobicity
Storage of torrefied pellets
Dust
Issues are closely linked to
- Biomass feedstock
- Torrefaction parameters
- Pelletization parameters
- Can be different case by case
Requires knowledge and further studies
Pellets from torrefied biomass
Single pellet press tool: Fast and only few grams of material needed
Set-up allows variation of: Temperature, pressure, particle size, moisture, and additive addition
Determination of: Compression energy, friction and quality analysis of pellets Earlier tests have shown correlation between friction and energy consumption of industrial scale pellet press
Pellets from torrefied biomass
Example: Pelletization of torrefied pine tree
Friction increase when pelletizing torrefied pine tree
Increase of friction for torrefied biomass Pellet mill: Energy requirements increase Capacity gets lower More heat development in press
Pellets from torrefied biomass
What can we do to improve the pelletizing properties?
Increase moisture content
Increase die temperature
Add a lubricant to reduce friction
Additives
Change press channel dimensions
Torrefaction parameters
Temperature
Reaction time
…
We have looked on a few of them Some examples
Pellets from torrefied biomass
Example: Pelletization of torrefied pine tree
Increase of die temperature 125 - 190 °C
Friction is reduced by 50%
No effect on the untreated pine tree
Pellets from torrefied biomass
Friction is reduced by 50%
Example: Pelletization of torrefied pine tree
5 % water addition
Pellets from torrefied biomass
Friction is reduced by 70 % But… Negative impact on pellet strength
Example: Pelletization of torrefied pine tree
2% rape seed oil
Pellets from torrefied biomass
Parametric study – which parameters are the important ones
Design of experiments
- Torrefaction degree expressed as
mass yield (90.5% - 71.1%)
- Temperature 250 to 300 °C
- Moisture content (0 to 10%)
- Die temperature (125-180˚C)
- Particle size( small / big)
Pellets from torrefied biomass
Parametric study – which parameters are the important ones
Key results:
- Main parameters affecting friction and pellet durability are:
torrefaction degree, moisture content and die temperature
- High torrefaction degree increases friction and decreases pellet
strength
- Water addition and increasing temperature counteracts this
effect
Mathematical modeling of the interaction between the parameters
and their dependency is in progress and will be published soon
Pellets from torrefied biomass
Successful Pilot and production scale trials
- Partners in SECTOR project have successfully produced several tons of torrefied pellets
- Large scale production facilities in SECTOR project
- Energy center of The Netherlands (ECN)
- National Renewable Energy Center, Spain (CENER)
- Umeå University & Swedish Agricultural University (SLU), Sweden
- Topell, The Netherlands
- Feedstock: Pine, spruce, poplar, willow, forest residues, straw,…
- Material are used in logistics, storage and combustion trials right now
Successful demonstration of the technology
Briquetting of torrefied biomass
Spruce 240 °C 260 °C 280 °C
Briquetting of torrefied biomass Feeding tank
Conditioning of raw material : Water addition
Briquetting press: outlet Cooling conveyor
Production trials with Industry partner C.F. Nielsen Briquette press manufacturer
Briquetting of torrefied biomass
Results from production trials
Raw material
Spruce (fresh)
240 C
260 C
280 C
Density (raw material) kg/m3 153 181 157 162
Moisture % 13,4 5,2 4,3 4,8
Particle size min mm 1x1 0,1x0,1 0,1x0,1 0,1x0,1
Particle size max mm 10x5 5x2 5x2 5x2
Process
Power consumption A 70 85 85 80
Die Temperature C 160 165 200 205
Strokes per min 1/min 269 269 269 269
Strokes number n 13 9 16 17
Capacity (measured) kg/h 600 660 600 600
Product
Diameter mm 59 59 60 59,5
Length mm 155 115 162 159
Volume cm3 424 314 450 442
Weight g 446 318 456 444
Density (briquette) kg/m3 1053 1012 1013 1005
Briquetting of torrefied biomass Continuous briquetting of torrefied spruce without stoppages
Briquette quality is good but slightly decreasing for higher torrefaction temperatures
Water addition can improve the briquette strength, there is an optimum moisture content further tests required to confirm
Unit Density is around 1000 kg/m3 but can most likely be improved by adjusting die diameter and length and by adding additives. Latest developments shows densities up to 1300 kg/m3 for small tests.
Briquette surface is porous, flake like structures – Latest developments shows improvements
Process needs further optimization to obtain a sealed surface of the briquette
Best results when briquettes remain under heat and pressure for longer time
Baking of the briquette
Friction increases with degree of torrefaction (Temperature increase), however Capacity and Power consumption of press remains stable
Market situation for torrefied fuels
Barriers for commercialization of torrefied pellets
Technology is ready but, manufacturers and buyers are risk averse
to new technologies
Producers are willing to implement torrefaction technology and
produce torrefied biomass, but before investing in a full size
commercial plant they need long term off take contracts from
bankable customers
Buyers are not un-willing to buy, but first they need to prove that
promises concerning torrefied biomass use are met, including
quality and volume guarantees, and on operational issues.
Classic “Chicken and Egg” problem
One has to make the first move
Thank you for your attention!
For more information please contact:
Wolfgang Stelte
Consultant, Ph.D.
Biomass & Biorefinery
Danish Technological Institute
Energy and Climate
Mobile: +45 7220 1072
wst@teknologisk.dk
Gregersensvej 2
DK- 2630 Taastrup
Denmark
Tel. +45 7220 2000
Fax +45 7220 2019
www.teknologisk.dk
"The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 282826."
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