Torrefaction technology by ECN

1

Torrefaction for biomass upgrading into commodity fuels

Jaap Kiel

IEA Bioenergy Task 32 workshop “Fuel storage, handling and preparation and system analysis for

biomass combustion technologies”, Berlin, 7 May 2007

Meeting Cargill, 15 May 20062 Torrefaction for biomass upgrading into commodity fuels – Jaap Kiel

Presentation overview

• ECN

• Torrefaction principles

• ECN TOP technology

• Economics

• Development status and market implementation

2


Energy research Centre of the Netherlands

• Independent energy research institute

• 650 staff

• Annual turnover:80 million EURO

• Activities:- Biomass, Solar, Wind

- Fuel Cell Technology- Clean Fossil Fuels

- Energy Efficiency

- Policy Studies

in the dunes of North Holland

ECN develops high-quality knowledge and technology

for the transition to a sustainable energy supply and brings it to the market


Torrefaction for biomass upgrading

general process description

Torrefaction

mass energy

Gas

Biomass

Torrified

biomass

1 0.7

0.3

1 0.9

0.1

0.7

0.9= 1.31Energy densification (E/kg)

Temperature: 200-300 °C

Pressure: near atmospheric

Heating rate: <50 °C/min

Absence of oxygen

Product: solid fuel

Residence time 10-30 min

Particle size < 4 cm thickness

3


Friable and less fibrous

19 - 22 MJ/kg (LHV, ar)

Hydrophobic

Preserved

Reduced contaminant level

Homogeneous

Torrefaction and pulverisation

Fuel powder

From biomass/waste to commodity fuels

Tenacious and fibrous

10 - 17 MJ/kg (LHV, ar)

Hydrophilic

Vulnerable to biodegradation

Contaminated

Heterogeneous

Agricultural residues

Mixed

waste

Woody biomass

Pelletisation

Fuel pellets

Bulk density 750-850 kg/m3

Bulk energy density 15-20 GJ/m3

Superior fuel properties:

• Transport, handling, feeding

• Milling

• Combustion/gasification

• Feedstock bandwith

• Standardisation


Decomposition regimes

D

drying (A)

Extensive

Devolatilisation

and

carbonisation

(E)

Limited

devolatilisation

and

carbonisation (D)

depolymerisation

and

recondensation

(C)

A

E

D

C

E

A

D

C

glass transition/

softening (B)

Hemicellulose Lignin Cellulose

100

150

200

250

300

Tem

perature (°

C)

Hemicellulose Lignin Cellulose

100

150

200

250

300

Tem

perature (°

C)

TORREFACTIO

N

4


Starting points ECN TOP technology development (1)

• Torrefaction (combined with pelletisation) has the potential of becoming

a key unit operation in biomass upgrading schemes for a wide range of

applications, including:

− Biomass storage and (long-distance) transport – biomass import

− Co-firing in pf boilers

− (Co-)firing in entrained-flow gasifiers for producing power (IGCC) or

transportation fuels (e.g., Fischer-Tropsch diesel)

− Small-scale pellet boilers and stoves

⇒ Torrefied biomass pellets may become a biomass commodity fuel


Starting points ECN TOP technology development (2)

• Torrefaction principle not new, but many aspects relevant to application

for upgrading biomass into biomass fuel for thermal conversion

processes were not addressed, including:

− Scale of operation in relation to reactor technology and process

layout

− Characterisation and quantification of product quality and how this

relates to process conditions

− Nature and quantity of emissions

− Prospects of heat integration including utilisation of the energy

containing torrefaction gases

− The economic viability of torrefaction as a biomass upgrading

technique for bulk applications

⇒ 2002 start ECN TOP technology development

5


Proof-of-concept approach

Continuous screw

reactor (pyromaat)

Batch reactor

TGA analysis

Pellet press (batch)

Torrefied

biomassBiomassCutting mill

Lab-scale combustion

Simulator (LCS)Torrefaction

gas

Sampling methods

Analysis methods

Product distribution (M & E yields)

Pellet quality

Grindability

Combustibility

Torrefaction

database

Process

simulation

&

design tools

20 l batch reactor

5 kg/h screw

reactor


TorrefactionTypical experimental results

Torrefaction

32 min, 260 ºCFeed: Willow

Size: 10 - 30 mm

LHV = 14.8 MJ/kg (ar)

MC = 14.4%

Fixed carbon: 16.8 %

Torrefied Willow

Size: 10 - 30 mm

LHV = 18.5 MJ/kg (ar)

MC = 1.9%

Fixed carbon: 22.1%Mass yield: 75.3% (ar)

Energy yield: 94.3% (ar)

Gas phase composition

CO 0.1 %

CO2 3.3 %

H2O 89.3 %

acetic acid 4.8 %

furfural 0.2 %

methanol 1.2 %

formic acid 0.1 %

remainder 1.0 %

Tad = 1045 ºC

6


Grindability of (torrefied) biomass

-

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)

chipper capac

ity (kW

th)

-

10

20

30

40

50

60

70

80

90

- 0.5 1.0 1.5


Po

wer

consum

ption (

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)

-

10

20

30

40

50

60

70

80

90

- 0.5 1.0 1.5


Po

wer

consum

ption (

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)

Torrefaction leads to a dramatic decrease in required milling power

and increase in milling capacity


Torrefaction of willow (280 oC, 17.5 min)Product distribution

87.5

1.4 1.7 1.48.0

94.9

0.1 1.6 3.4

0

10

20

30

40

50

60

70

80

90

100

Solid Permanent

Gas

Organics Lipids Reaction

Water

Mass y ield

Energy y ield

0%

25%

50%

75%

100%

CO CO2 Other

mass

composition

energy

composition

0%

10%

20%

30%

40%

50%

60%

70%

Acetic Acid

Methanol

2-Furaldehyde

Hydroxyaceton

1-Hydroxy-2-butanon

Phenol

Propionic acid

Furan-2-methanol

5-Methyl-2-furaldehyde

Acetaldehyde

Methylacetate

Other

mass composition

energy composition

Main product groups (dry basis)

Permanent gases

Organics

7


Combustion reactivity of torrefied woodLab-scale Combustion Simulator

experiments

0

10

20

30

40

50

60

70

80

90

0 500 1000 1500 2000 2500time [ms]

co

nve

rsio

n [

%]

or

LO

I [%

d.b

.]

100

high-volatile coal low-volatile coal torr. (300°C) demolition wood HVC (LOI) LVC (LOI) torr. (300°C) demolition wood (LOI)torr. (280°C) prune wood torr. (280°C) prune wood (LOI) torr. (280°C) demolition woodtorr. (280°C) demolition wood (LOI) prune wood (fresh) prune wood (fresh, LOI)

High reactivity for

torrefied wood


Semi-industrial pelletisation tests

Features:

• 10 kg/h

• No automatic moisture supply

• Preliminary findings:

− Easy pelletisation

− Low energy input required

− Pellet quality strongly dependent on pelletisation conditions

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TOP pellets vs. wood pellets

Properties unit Wood Torrefied biomass

low high low high

Moisture content % wt. 35 3 7 10 1 5

Calorific value (LHV)

dry MJ/kg 17.7 20.4 17.7 17.7 20.4 22.7

as received MJ/kg 10.5 19.9 15.6 16.2 19.9 21.6

Mass density (bulk) kg/m3 550 230 500 650 750 850

Energy density (bulk) GJ/m3 5.8 4.6 7.8 10.5 14.9 18.4

Pellet strength - -

Dust formation Moderate High Limited Limited

Hygroscopic nature Water uptake Hydrophobic

Biological degradation Possible Impossible

Seasonal influences

(noticable for end-user)High Poor

Handling properties Normal Normal

Wood pellets TOP pellets

Good

Swelling / Water

uptake

Very good

Limited swelling /

Hydrophobic

Possible

Moderate

Good Good

Impossible

Poor


ECN directly heated torrefaction technology

Drying Torrefaction Cooling

Heat exchange

Biomass TOP pellets

Air

Utillity fuel

Flue gas

Combustion

∆P

Torrefactiongas

Flue gas

Flue gas

Gasrecycle

Pelletisation

Features:

• High energy efficiency (> 90%)

• Heat integration

• Conventional drying and

pelletisation

• Compact moving bed

technology

• Cost effective

15-20%

moisture

9


ECN torrefaction technology Innovative moving bed reactor

• Compact reactor

• Small footprint

• High heat transfer rates

• Accurate T-control

• Uniform product quality

• Feedstock flexibility

• Low capital investment

Pilot-scale torrefaction reactor at ECN


Total capital investment – study estimate (TOP pellets vs. wood pellets)

Total Capital Investment TOP and Pelletisation

(Feedstock: 180 kton/a woodchips @ 50%mc)

0

1

2

3

4

5

6

7

8

TOP Process Conventional Pelletisation

TC

I (M

Euro

)

Drying

Torrefaction

Size Reduction and Pelletisation

Storage

Indirect Cost

Working Capital

10


Total production cost (TOP pellets vs. wood pellets)

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

Green Wood

Pellets

Saw Dust

Pellets

47 MW /

75 kton/a

MC = 50%

47 MW /

75 kton/a

MC = 35%

BASE CASE

47 MW /

75 kton/a

MC = 25%

47 MW /

36 kton/a

MC = 35%

47 MW /

112 kton/a

MC = 35%

Pro

du

ctio

n C

ost In

dic

ation

(E

uro

/GJ p

rodu

ct)

Total Cost Other Power

Support Fuel Personnel Maintenance

Depreciation and Financing Feedstock (=0 Euro/tonne)


Chain study (TOP pellets vs. wood pellets)

TOP process

(South Africa)Logistics

Conventional

Pelletisation

(South Africa)Logistics

(Co-)firing

coal-fired power stations

or entrained-flow gasifiers

North-West Europe

Sawdust

Sawdust

2.0 EUR/GJ0.7 EUR/GJ <2.0 EUR/GJ

<4.7 EUR/GJ

2.3 EUR/GJ0.7 EUR/GJ 2.9 EUR/GJ

5.9 EUR/GJ

Higher co-firing capacity

Lower capital investment

Higher co-firing flexibility

and availability

Favourable

economics!

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Road map ECN TOP technology development

2002 2003 2004 2005 2006 2007 2008 2009 2010

Waste

Green

biomass

Time

capacity 5-10 kg/h 100 kg/h 60-100 kton/a20 kton/a

Proof-of-concept

•Experimentally based process design

•Technology identification

•Knowledge base torrefaction

•Experimental infrastructure torrefaction

•Economic evaluation full-scale

(study estimate 30%)

•Set-up pilot phase of development

Prototype (pilot-scale evaluation)

•Pilot plant / prototype technology

•Demonstration technical feasibility

•Process and product characterisation (design data)


(preliminary estimate 20%)

•Business plan(s)

(technical demo, semi-commercial)

Technical demonstration

•Demonstration plant (semi-commercial)

•Technical feasibility (refined design)

•Product applications (large scale)


(definite estimate <10%)

•Business plan(s)

(commercial operation)

Proof-of-

principle

Prototype

(pilot-scale)

Commercial

demonstration

Technical

demonstrationProof-of-concept

Proof-of-

principleProof-of-concept

Prototype

(pilot-scale)

Technical

demonstration


ECN TOP technology development – 2007 activities

• Pilot-scale testing

− Validation of reactor and process concept

− Optimisation of process conditions for a broad feedstock range

− Industrial pelletisation tests

− Extensive quality evaluation TOP pellets

(e.g., hygroscopic nature, biodegradation, strength, milling

characteristics, combustion/gasification reactivity)

• Demonstration plant basic design

• Business plan for technical demonstration(s) through BO2 Energy Concepts

• Continued basic R&D (co-operation with TU Eindhoven)

− Contaminated biomass (residues) and waste

40-100 kg/h torrefaction

pilot-plant at ECN

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In conclusion

• ECN TOP technology allows cost effective production of commodity fuels from a wide range of biomass/waste feedstocks with a high energy efficiency (>90%)

• ECN TOP fuels show:

− High energy density

− High water resistance

− No/Limited biological degradation

− Excellent grindability

− Good combustion properties

• Fields of application:

− Long distance biomass transport

− Co-firing in pf boilers

− (Co-)firing in entrained-flow gasifiers

− Small-scale pellet boilers/stoves

• In 2007 pilot-plant testing and initiation of demo-projects


For further information please contact:

Dr.ir. Jaap Kiel

e: [email protected]

t: +31 224 56 4590

w: www.ecn.nl

ECN

P.O. Box 1

NL 1755 ZG Petten

the Netherlands

Documents

Torrefaction technology by ECN