Philippe Girard-Gasification Principles

BIOMASS GASIFICATION

Philippe GIRARD, Patrick ROUSSET, Laurent VAN DE STEENE

Biomass Energy Reaserch Unit

25-29 DE JUNHO 2007 FLORIANOPOLIS-SC- BRAZIL

A long historyEarly XIXeme : In Europe coal gasification provide gas to cities.

1860 : First gas engine

1900 : First gas engine operating with producer gas.

1910-1920 : Georges Imbert develop a wood gasifier.

1945 : 500 000 vehicles are equipped with gasifiers.

Early 70 : the first oil crisis reactivate the interests for biomass gasification

XXIeme century : Environment

Introduction

Introduction

Définitions

• Obtain gaseous fuel through biomass heating at high temperature (900°C)

• Different medium

Air : the most common

- adapted for gasifier up to 50 MWth

- gives gas of poor heating value (4-6 MJ/Nm3 ) due to dilution in N2

Oxygen : expensive dedicated to large plant

- heating value 10 -15 MJ/ Nm3

Steam : heating value of 13 - 20 MJ / Nm3

- need of additional heat supply, due to endothermic reactions involved

Définitions

2 2C H O CO H+ → +

2 2C CO CO+ →

2 2 2CO H O CO H+ → +

2 4 23CO H CH H O+ → +

2 4C H CH+ →

Steam gasification (primary reaction)

Boudouard reaction

Steam reforming

Water – gas shift reaction

Hydrogenating gasification (methanisation)

MV + O2 → CO2 + H2O

C + O2 → CO2 (+ CO)

Pyrolyse

First step of air gasification

Gasification

H2O

H2O

CO2

H2

H2

CO

∆ Η

∆ Η

~14,3 MJ/kg

~10,9 MJ/kgC + H2O CO + H2

C + CO2 2 CO

Gazéification

pyrolyseOxidations

homogeneous et heterogeneous

EnergyGasification media H2O ; CO2Char

Combustion

Définitions

Définitions

Schematic gasification

Mainly 2 heterogeneous reactions (C-H2O et C-CO2 )

The reaction is endothermic

kinetics : slower than O2 oxidation (combustion)

Around 50 times slower for H2O

around 150 times slower for CO2

Mechanisms concerned

The same as combustion

+ heterogeneous reactions typical from gasification

These reaction are often limiting

Définitions

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0 2000 4000 6000

tim e (s)

deg

ree

of

con

vers

ion

X

900°C (1)

900°C (2)

900°C (3)

900°C (4)

900°C (5)

900°C (6)

1000°C (1)

1000°C (2)

800°C (1)

800°C (2)

Time (s)

800 °C900 °C1000 °C

20 % H2O30 mm

TDéfinitions

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0 1000 2000 3000

time (s)

deg

ree

of

con

vers

ion

X

0,2 (1)

0,2 (2)

0,2 (3)

0,4 (1)

0,4 (2)

0,1 (1)

0,2 (4)

0,2 (5)

0,2 (6)

0,1 (2)

0,1 (3)

rate

X

10 % 20 %40 %

900 °C30 mm

H2ODéfinitions

The products

Combustible gas

CO, H2, CH4, CnHm, H2O, CO2, tars, N2

Particles in the gas (fines unconverted carbon and ashes)

Bottom ashes (C content very often important – Yield affected)

NCV

Air gasification : ~ 3-7 MJ/Nm3

Oxygen gasification:

Steam gasification :~ 9-15 MJ/Nm3

Energy ( hot gas and losses)

Air gasification Fixed bed Down draft

Fixed bed Up draft

Circulating fluidized bed

Biomass moisture %mh 6-20 n.d. 13 – 20

Particles mg/Nm3100 – 8 000 100 - 3 000 8 000 - 100 000

Tars mg/Nm3 500 - 6 000 10 000 - 150 000 2 000 - 30 000

Gas NCV MJ/Nm3 4.0 - 5.6 3.7 - 5.1 3.6 - 5.9

H2% vol. 15 – 21 10 – 14 15 – 22

CO % vol. 10 – 22 15 – 20 13 – 15

CO2% vol. 11 – 13 8 – 10 13 – 15

CH4% vol. 1 – 5 2 – 3 2 – 4

CnHm% vol. 0.5 – 2 n.d. 0.1 - 1.2

N2% vol. difference difference difference

The products

Tars

More than 100 compounds :

- Acids (acetic, formic)

- Alcohols (methanol, ethanol)

- Phenols (phenol, cresol)

- Guaïcols (guaïcol, creosol)

- Furans

- Aldehyds et ketons (formaldéhyde)

- Aromatic compounds (benzene, toluene, PaH, Nitrous aromatic)

The products

Results from the pyrolysis step : unconverted volatile maters and tertiary compounds formed at high temperature

Combustion

Main biomass applications

Electricity

Steam engine

Alternator

Heat Heat

Furnace and boiler

COMBUSTION

Heat

Global electric efficiency :Steam engine : 10-15 %Steam turbine : 20-30 %

Steam turbine

Heat (gas)

Producer gas (clean)

Electricity

Steamengine/turbine

Heat heat

Fuel cells

Diesel/ gasolineMethanol

Fischer Tropsch

Electricity

Hydrogen rich gas engine/ Gas turbine

Gasification applications


Gas cleaning (the gasification problem) objectives depend of the applications. For engines :

• tars elimination below 10 mg/Nm3 (ppm for BTL)

• for engine application gas cooling from 600 to 30°C

• sulphur content below 1 mg/Nm3 & alkali below 0.1 mg/Nm3 (gas

turbine)

COMPLEX PROBLEM

= create project drawbacks and failures

Several Alternatives - catalytic cracking (ageing)

- scrubber (waste water treatment)

- washer (idem)

- dry cleaning system

- electro-precipitator (60 - 80 °C)


engines Gas turbines methanol Synthesis

Calorific value MJ/Nm3 4-6 - Maximum temperature °C lowest 450-600 Particles mg/Nm3 < 50 < 30 < 0.02 Particles size µm < 10 < 5 Tars mg/Nm3 < 100 0 or vapour < 0.1 Alkali metals ppb na 20-1000 NH3 mg/Nm3 n.l. n.l. < 0.1 HCl mg/Nm3 <1 < 0.1 Sulphur compounds (H2S ; COS) mg/Nm3 <1 < 1 CO2 % vol. n.l. n.l. <12, (n.l.)

Gas specifications for different applications (indicative)

Gasification to electricity

Electricity (and heat)

Steamengine/turbine

Gas turbineGas engines(internal combustion)

15-20 % ~ 25-35 % 30-40 %

Steam turbine

Boiler

Gasificationcombined cycle (IGCC)

~ 50 %

15-20 %

Combustible gas

Biomass gasification applications

Gasification to transport fuels


Methanol

Gasificationair/ or oxygen

Pressurised or athm.Direct or indirect

Pre treatment• Drying• Grinding• Pelletisation• Pyrolysis

Indirect processes

Conditioning• Reforming• Shift• CO2 removal

Gas cleaning•Particles•Tars•inorganic

SynthesisGas or

liquid phase

CHP End use

Biodiesel

DME

LNG/CNG

Gasification included in the bio-refinery concept


BioethanolEsterification

Methanol

Herbaceousbiomass

Torefaction

Biomasspre treatment

Oil/sugarseparation

Flash pyrolysis

SyngasProduction

SynthesisBiodiesel

DME

Chemicals

Woodybiomass

Plantation

Plastics

Electricity

Gas cleaning

tars

SLURRY

Waste materials

Thermo-chemical processes

Fixed bed

Moving bed

Fluidized bed

Powder injection

Sol

id m

ovem

ent w

ithi

n th

e re

acto

r

Res

iden

ce ti

me

Tem

pera

ture

Up draft

Down draft…

Moving grate

Rotating furnace…

Bubbling fluidized bed

Circulating fluidized bed

Entrained flow…

burners…

Fixed bed

Fluidized bed

updraft

downdraft

Staged gasification

bubbling

circulating

Entrained flow

Gasification technologies

UP draft gasifieur

Capacity :

thermal : 1 à 5 MW

Feedstock :

capacity : 0.2 à 1 tonne dry/h

size : 5 à 100 mm

moisture content : 10 à 60 %

Gas quality :

NCV : 4000 à 5500 kJ/Nm3

Temperature : 150°C à 300°C

Tar content : 100 g/m3

Application :

- heat

State of art :

- commercial but limited application (Volund)


Down draft gasifier

Biomass

Capacity :

thermal : 20 kW à 2 MW

feedstock :

capacity : 5 à 400 kg db/h

size : 20 à 100 mm

moisture < 20 %

Gas :

Composition : • CO : 20-25 %, H2 : 11-17%, N2 : 48 - 54 %

NCV : 4500 à 5500 kJ/m3

Temperature : 400°C à 600°C

Tar content : 0.5 à 3 g/m3

Application :

- heat and electricity

State of the art :

- commercial but still R&D need


Up draft

S E C H A G E

O X Y D A T IO N

P Y R O LY S E

G A Z

A IR

B IO M A S S E

R E D U C T IO N

Down draft

GAZ

AIRAIR

SECHAGE

REDUCTION

PYROLYSE

OXYDATION

BIOMASSE

+ Allow moist biomass- Tar content of the gas- Risk of tar condensation- Limited to thermal applications

+ high efficiency- Not up scalable (< 350 kWel)- Limited biomass moisture ct (< 15 %)

+ Robust and simple technologies


co-courant fixed bed

Martezo, FranceLimited to 150 KWe


Xylowatt, Belgique80-2000 KWth

Down draft



Grain processing400 KWth

Mukunda50 KWe

CICB350 KWe

Ankur250 KWe

INDIA

Stage gasification

Viking Gasifier, DTU, Dk250 KWth


Viking Gasifier, DTU, Dk250 KWth


Stage gasification

TKe Gasifier, Dk3 MWth

AIR

GAZ

CENDRE

BIOMASSE

GAZ

+ easy scale up+ easy temperature and residence time control+ good heat transfer (sand)- High gas particle content- Limited moisture content < 20 %- Minimum application size : ~10 MWe

Bubbling circulating entrained

+ cleaner gas+ ash slaging- Sizing of biomass - Short residence time

+ larger tolerance towards feedstock(nature, size)

+ use of catalyst in the bed (dolomite)-Required appropriate sizing

Fluidized bed


Fluidized bed

capacity :

5 à 100 MWth

Feedstock :

1 à 20 tonnes dry/h

Applications :

- Heat

ex : district heating Finland

- Power generation

- co-combustion

- IGCC

State of the art

- commercial for heat & co-combustion

(Foster Wheeler, Lurgi, TPS, …)

- demonstration R&D for IGCC (Varnamo, Burlington, Repotec)


CHP-plant Gussing, Austria


Fluidized bed

CHP-plant Gussing, Austria

4,5 MW thermiqueCapacité : 8 MW

2 MW électrique


Fluidized bed

BIOFLOWpar Sydkraft à VarnamoPressurized Circulating fluidized bed18 MW, 8 MWe the only unit who demonstrate a gas turbine with producer gas


Lit fluidisé sous pression

Lit fluidisé circulant

Lit fluidisé dense

Contre-courant

Co-courant

1 MW 10 MW 100 MW 1000 MW1 kW 10 kW 100 kW

0,2 kg/h 2 kg/h 20 kg/h 200 kg/h 2 t/h 20 t/h 200 t/h

Gasification economics

Economic viability of the different processes

Investment cost breakdown (wood)

Gasification

Atmospheric Pressurised

% of total plant cost Reception storage and handling

15.4 11.1

Size reduction and screening

7.7 5.6

Drying 19.2 13.9

Gasification 38.5 55.5

Gas scrubbing and waste water treatment

19.2 13.9

Total 100 100


Plant capacity Power + heat Mwel + MWth

Biomass Consump. Area required Power and heat

prod t/h t/d t/a ha

5t/ha ha

20t/ha TWh/a each

1 + 1 0.3 8 1 560 313 78 5

5 + 5 1.6 37 7 800 1 560 390 25

10 + 10

3 75 15 600 3 125 780 50

30 + 30 9 225 46 900 9 375 2 300 150

100 + 100 31 750 156 250 131 250 7 800 500

300 + 300 93 2500 486 750 93 750 23 500 1500

Large scale applications increase logistics and transportation costs


Gas treatment remain a problem : - particles- tars- alkali- Sulfur

Gasification advantages

Higher electric yield (engines and gas turbines) than conventional steam cycles

Better emission control and emission reduction

Large potential for medium size plant (1 to 5 MWe)

Conclusions

Feed material pre-treatment : requirements vary according to gasification technology

Drying below 10 to 15%

Particle size 20 to 80 mm down sizing, compaction

Leaching to reduce Nitrogen and Alkali content

Possibility for co-gasification with coal, diesel fuel, MSW

Technology to be use will depend on the gasification process (concentration and nature)

Particles Conventional filtration (cyclone, bag house filters, washer)

(100 mg à 100 g/Nm3)

Hot filtration (ceramic or metallic filters)

Tars Washer, scrubbers (1 mg à 150 g/Nm3)

Thermal cracking (>1000 °C)

Catalytic cracking (dolomite)

Pb condensation, energy efficiency

Waste water treatment

Energy efficiency

Poisoning, aging

Conclusions

Cost (operating and investment

Conclusions

Characteristics– main scope CHP, however only heat demonstrated

– Capacity : 1 to 50 MWe

– Complete automation

– investment cost : 3000 to 5000 EUR/kW installed

– biomass cost constitute one of the major constraint (wastes)

Suppliers– less than 10 suppliers with references

– increasing reliability (largely demonstrated with coal or petroleum wastes)

Niche market– green electricity

– Wastes

Biofuels market reactivate the research (large scale)

Situation in industrialized countries

Documents

Philippe Girard-Gasification Principles