solid biofuels from torrefied biomass - sector: home · 2014-04-17 · process power consumption a...

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)


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


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


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


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


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


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



Increase of die temperature 125 - 190 °C

Friction is reduced by 50%

No effect on the untreated pine tree


Friction is reduced by 50%


5 % water addition


Friction is reduced by 70 % But… Negative impact on pellet strength


2% rape seed oil


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)


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


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

[email protected]

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."

solid biofuels from torrefied biomass - sector: home · 2014-04-17 · process power consumption a...

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