ECN’s torrefaction-based BO technology – from pilot to demo · 7 ECN’s torrefaction-based BO 2-technology from pilot to demo – Jaap Kiel Biomass torrefaction for energy applications
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ECN’s torrefaction-based BO2-technology – from pilot to demo
Jaap Kiel
Presented at IEA Bioenergy workshop Torrefaction, Graz Austria, 28 January 2011
ECN-M—11-024 FEBRUARY 2011
2 ECN-M—11-024
ECN’s torrefaction-based BO2-technology – from pilot to demo
Jaap Kiel
IEA Bioenergy workshop Torrefaction, Graz Austria, 28 January 2011
2 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Presentation overview
• ECN – Energy research Centre of the Netherlands
• Torrefaction design challenges
• Initial small-scale R&D
• ECN’s torrefaction-based BO2-technology
• Pilot-scale testing
• Demonstration and market introduction
• Conclusions
BO2-technology = “the alternative to CO2”
3 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Energy research Centre of the Netherlands
• Independent research institute
• 650 employees • Annual turn-over:
80 million Euro • Main activities:
- Biomass, Solar, Wind
- Energy efficiency
- Policy studies
In the dunes of Petten, North Holland
ECN develops and brings to market high-level knowledge and technology for a sustainable energy system
4 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Biomass – a difficult energy source ….
• … in view of:
Logistics (handling, transport and feeding)
End-use (combustion, gasification, chemical processing)
• Difficult properties are:
Low energy density (LHVar = 10-17 MJ/kg)
Hydrophilic
Vulnerable to biodegradation
Tenacious and fibrous (grinding difficult)
Poor “flowability”
Heterogeneous
5 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Torrefaction for upgrading biomass
Gas
Torrefaction
200-300°C
mass energy
Dry
biomass
Torrefied
biomass
1 0.7
0.3
1 0.9
0.1
0.7
0.9 = 1.3 1Energy densification (MJ/kg)
Process parameters Temperature: 200-300°C
Residence time: 10-30 minutes
Particle size: < 4 cm
Absence of oxygen
Pressure: near atmospheric
6 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Torrefaction ….. how difficult can it be?
Small-scale coffee roasting machine in
Bourg St. Maurice, France
7 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Biomass torrefaction for energy applications
• Not straightforward !
• Absence of oxygen requires air-tight system
• Torrefaction should be considered as a separate thermal regime, distinctly different from drying, slow pyrolysis or charcoal production
• Characteristic features: Modestly exothermal reaction Condensables composition and behaviour Nature and behaviour of the solid product
• Optimum energy efficiency is crucial in view of overall cost and sustainability
• Reactor and process should allow large-scale production with minimal environmental impact
8 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Design challenges
• Torrefaction process control – condensables, exothermicity, product quality control (in view of subsequent densification and end-use)
• Cost – CAPEX, OPEX, availability
• Energy efficiency (also in view of CO2 footprint) heat integration use energy content torrefaction gas
• Feedstock flexibility
• Environmental impact (avoid waste streams)
• Plant capacity (at least 5-15 tonne/h dry input)
• Energy densification: torrefaction + pelletisation
Torrefaction reactor and process design should be chosen carefully
Dedicated pelletisation procedures should be developed
9 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Initial small-scale torrefaction R&D at ECN
• ECN was one of the first to recognise the potential of torrefaction for biomass-to-energy purposes
• Initial small-scale research started in 2002-2003, revealing: Quantitative relation between torrefaction conditions (residence time, temperature) and product properties (solid + gas) for a broad range of biomass feedstocks
Underlying mechanisms (structural changes in the biomass)
Pelletisation behaviour of torrefied biomass
• Based on the small-scale research, dedicated reactor and process concepts were developed, aiming at: good process control, low investment cost, high capacity, high feedstock flexibility, high energy efficiency and minimum environmental impact
• To achieve high energy efficiency, heat integration using the energy content of the torrefaction gas is crucial
10 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Bench-scale testing 20 l batch reactor
5 kg/h Auger reactor
(screw reactor)
Torrefaction of willow (280 oC, 17.5 min)
Main product
groups (dry basis)
Permanent gases
Organics
11 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
10
20
30
40
50
60
70
80
90
0.5 1.0 1.5 Average particle size (mm, volume based)
Pow
er c
onsu
mpt
ion
( )
C(270,21) C(280,18) C(290,12) W(290,24) W(260,24) Willow (MC=10 - 13%) Willow (dried) Cutter wood AU bituminous coal Borssele run demolition wood D(300,11)
10
20
30
40
50
60
70
80
90
0.5 1.0 1.5
Pow
er c
onsu
mpt
ion
( kW
e/M
Wth
)
C(270,21) C(280,18) C(290,12) W(290,24) W(260,24) Willow (MC=10 - 13%) Willow (dried) Cutter wood AU bituminous coal Borssele run demolition wood D(300,11)
C(270,21) C(280,18) C(290,12) W(290,24) W(260,24) Willow (MC=10 - 13%) Willow (dried) Cutter wood AU bituminous coal Borssele run demolition wood D(300,11)
0.0 0
40
80
120
160
200
240
280
320
360
0.2 0.4 0.6 0.8 1.0
Average particle size (mm, volume based) M
ill c
apac
ity (
kWth
)
Grindability of (torrefied) woody biomass
Torrefaction leads to a dramatic decrease in required milling power and increase in
milling capacity
0.0 0
12 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Reactivity of torrefied wood Lab-scale experiments to mimic pulverised-fuel
combustion conditions
High reactivity for
torrefied wood
0
10
20
30
40
50
60
70
80
90
100
0 500 1000 1500 2000 2500
t [ms]
conv
ersi
on [%
]
high-volatile coal low-volatile coal torr. (300°C) demolition wood
torr. (280°C) prune wood torr. (280°C) demolition wood prune wood (fresh)
13 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
BO2-technology Features:
• Conventional drying and pelletisation
• Compact dedicated moving bed technology with direct heating (no moving parts)
• Heat integration
• High energy efficiency (> 90%)
• Cost effective
• IP is patent protected
Drying Torrefaction Cooling
Heat exchange
Biomass BO2pellets
Air Utillity fuel
Flue gas
Combustion
P
Torrefaction gas
Flue gas Flue gas
Gas recycle
Pelletisation
15-20%
moisture
14 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Torrefaction pilot-plant (50-100 kg/h)
Pre-drying Feeding
15 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
• Testing history: Start-up 2008 Over 1000 hours of operation (day runs + 50-100 hour runs); >30 tonnes of torrefied material produced Currently regular 50-100 hour runs Biomass feedstock: poplar, pine, forestry residues (softwood/hardwood mixtures), agricultural residues (POR) Conditions: 220-280 °C torgas inlet temp., throughput approx. 60 kg/h (input basis)
• Modifications after initial tests: New continuous discharge system Modifications to reactor design (better scale-up) Modifications to the gas loop (long-duration operation)
Pilot-scale torrefaction
16 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Production of 1-10 tonne test batches
17 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Pilot-scale torrefaction – results of typical run
0
50
100
150
200
250
300
15-03-10 0:00
15-03-10 12:00
16-03-10 0:00
16-03-10 12:00
17-03-10 0:00
17-03-10 12:00
18-03-10 0:00
18-03-10 12:00
19-03-10 0:00
19-03-10 12:00
20-03-10 0:00
TOR_TIA2001L TOR_TIA2001M TOR_TIA2001O TOR_TIA2252
Torrefaction reactor temperatures
Tem
pera
ture
(oC
)
Mixture: poplar, spruce, birch and ash wood
27.8% moisture
Poplar chips 13.6% moisture
18 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
• Smooth operation, easy start-stop
• High feedstock flexibility, limited pressure drop and no bridging given proper sizing of the feedstock
• Good control of condensables in the torgas
• Torrefaction modestly exothermic, reactor shows good active temperature control enabling good product quality control
• Torrefied product pyrophoric / self-igniting, passivation needed
Pilot-scale torrefaction – general findings
19 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
• Torrefied material from pilot-plant subjected to semi-industrial-scale pelletisation tests at CPM:
Good quality pellets can be produced without
additional binder But case-by-case tuning of the pelletisation conditions (e.g. die type) required Good control of torrefaction conditions essential for proper pelletisation performance
Pilot-scale pelletisation
20 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
• ECN teamed up with Vattenfall to prepare for demonstrating the technology
• Contract negotiations with a technology supplier with world-wide presence for scale-up and commercial market introduction in final stage
• Demonstration unit scheduled for start-up by end 2011
• Supporting R&D aimed at: Further process improvement and simplification Broadening of the feedstock range Further optimisation of torrefaction + densification Product quality optimisation based on extensive logistics and end-use performance testing with test batches produced at pilot/demo scale:
Co-firing in pf boilers (Co-)gasification in entrained-flow gasifiers (IGCC or biofuels production)
BO2-technology – demonstration and market introduction
21 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
In conclusion • Torrefaction potentially allows cost-effective production of 2nd generation biomass
pellets from a wide range of biomass/waste feedstock with a high energy efficiency (>90%)
• Torrefaction pellets show: High energy density Water resistance No/Limited biological degradation and heating Excellent grindability Good combustion and gasification properties
• Torrefaction is a separate thermal regime and requires dedicated reactor/process design
• Torrefaction development in pilot/demo-phase; strong market pull for torrefaction plants and torrefaction pellets
• For ECN’s BO2-technology, demo-plant in preparation and industrial partnership for world-wide market introduction nearly established
22 ECN’s torrefaction-based BO2-technology from pilot to demo – Jaap Kiel
Thank you for your attention………
For more information, please contact:
Jaap Kiel
phone +31 224 56 4590 e-mail kiel@ecn.nl internet www.ecn.nl
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