ECN’s torrefaction-based BO technology – from pilot to demo · 7 ECN’s torrefaction-based BO...

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”


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


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


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


Torrefaction ….. how difficult can it be?

Small-scale coffee roasting machine in

Bourg St. Maurice, France


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


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


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


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


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

)



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


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)


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


Torrefaction pilot-plant (50-100 kg/h)

Pre-drying Feeding


• 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


Production of 1-10 tonne test batches


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


• 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


• 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


• 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


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


Thank you for your attention………

For more information, please contact:

Jaap Kiel

phone +31 224 56 4590 e-mail [email protected] internet www.ecn.nl

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ECN’s torrefaction-based BO technology – from pilot to demo · 7 ECN’s torrefaction-based BO...

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