pyrolysis of biomass to produce bio-oil, biochar and combustible gas
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Pyrolysis of Biomass to Produce Bio-oil, Biochar and Combustible Gas
John EdwardsSchool of Engineering and Advanced Technology
Massey University
Energy Postgraduate Conference 2008
2
What is Pyrolysis?
“Pyrolysis is thermal cracking in the absence of oxygen.” Cedric Briens
“Pyrolysis is the thermal decomposition of organic material at elevated temperatures, in the absence of gases such as air or oxygen.” Greenpeace
Heat introduced, O2 excluded
An endothermic reaction
3
What is Biomass?
• “Biomass is all non-fossil organic materials that have an intrinsic chemical energy content.” Ralph Sims
• Distillers’ Grains, Coffee Grounds, Grape Seeds and Skins, Sugarcane Bagasse, Sawdust and Tobacco Leaves.
4
What Pyrolysis of Biomass Is Not
1. New
2. The Holy Grail of Renewable Energy.
Pyrolysis dates back to at least ancient Egyptian times.
5
Pyrolysis of Biomass
HEAT
Combusti
ble Gas
BiocharBiomass
Bio-OilVapour
Condensation
6
The Organic Chemistry
3C6H10O5 HEAT
Pyrolytic reaction using cellulose:
Liquid Bio-Oil
Combustible Gas
Biochar
C6H8O +8H2O +CH4+2CO+2CO2+ 7C
Water of Pyrolysis
7
Some Advantages of Pyrolysis of Biomass
• Carbon neutrality• Utilises otherwise waste biomass• Potential to be self-sustaining energy-wise• Increases bulk and energy density of
biomass• Source of valuable chemicals• Biomass source can be decoupled from the
energy utilisation
8
Fast Pyrolysis of BiomassObjective to maximize liquid yield
The three main variables in the pyrolysis process are:
• Reaction temperature.• Biomass heating rate.• Vapour residence time.
Moderate temperatures ≈ 500°C and short vapourresidence time are required to maximize liquid yield.
9
Fast Pyrolysis of BiomassProduct yields (dry feed basis) for pyrolysis of wood.
A.V.Bridgwater
Mode Conditions Liquid Char Gas
Fast pyrolysisModerate temperature,
short residence time 75% 12% 13%
Slow PyrolysisLow temperature, very long residence time
30% 35% 35%
GasificationHigh temperature, long residence time.
5% 10% 85%
10
Bubbling fluidised bed method
A.V. Bridgwater et al
Biomass feed
11
0
10
20
30
40
50
60
250 300 350 400 450 500 550 600 650
Reaction Temperature °C
Yie
lds
We
igh
t%
Yields vs Reaction Temperature for Grape Seeds and Skins 5 seconds residence time
Gas
Liquid
Char
Maximum liquid yield
0
5
10
15
20
25
30
35
40
Yie
ld %
2.5 secs 5 secs 20 secs
Vapour Residence Time
Liquid
Gas
Solid
Grape Skin Pyrolysis Yields vs Residence Time Reaction Temperature 500°C
13
Heat of pyrolysis vs heating value of product gas for grape skins
0.0
0.5
1.0
1.5
2.0
2.5
3.0
250 300 350 400 450 500 550 600 650
Reaction Temperature °C
Heat
kJ/g
Gra
pe S
kin
Feed
Heat of pyrolysis
Heating value of product gas
Self sustaining
14
Production of Ethanol from Corn
I nstitute for Chemicals and Fuels from Alternative ResourcesInstitute for Chemicals and Fuels from Alternative Resources
Mike Jacobson
1litre of ethanol = 800grams of distillers’ grains
Distillers’ grain has a heating value of 6 to 20 MJ/kgBulk density ≈ 400kg m-3
15
Options for Distillers’ Grains
PyrolysisDistillers’ Grains
Sequestration of Biochar
Heat of Pyrolysis provided by combustible gas
CO2
Ethanol Production
Pure Ethanol
16
Bulk and Energy Densities
Density Energy Density
Kg m-3 MJ kg-1 GJ m-3
Green whole wood chips 350 9.6 3.4
Pyrolysis Bio-Oil 1200 18.0 21.6
Ratio 1:3.4 1:1.9 1:6.4
Comparisons of Bulk and Energy Densities for Biomass and Bio-Oil
Phillip C. Badger, Peter Fransham
17
Mobile Pyrolysis Unit
400 kg/h Demo Unit
18
Comparison of Bio-oil with Heavy Fuel oilPhysical property Pyrolysis Bio-oil Heavy Fuel Oil
Water, wt% 15-30 0.1
Specific Gravity 1.2 0.94
Heating Value (MJ/kg) 13-19 40
Solids, wt% 0.2-0.1 0.2-1.0
Viscosity, (at 50°C) (cP) 40-100 180
pH 2.5
Oxygen, wt% 35-60 0.6-1.0
Dinesh Mohan et al
19
The Challenges For upgrading of bio-oil to transport fuels
• Low volatility
• Low heating value.
• High viscosity
• Corrosiveness
• Coking
Every biomass is different!
20
Alternatives to upgrading
• Gasification of bio-oil to syngas
• Combination of bio-oil with diesel
21
Opportunities
• New Zealand has a plethora of biomass from forest and agricultural waste, for example
• Bio-oil and biochar co-production can be economically, environmentally and climate friendly
22
ConclusionsPyrolysis of Biomass
• Rapidly developing technology
• Added Value Economy
• Carbon negative solution Environment
• Increased bulk and energy density EconomyEnvironment
• More work needs to be done for upgrading
to transport fuels
23
Distillers’ Grains Biomass
24
Distillers’ Grain Biochar
25
Distillers’ Grain Bio-oil
26
Acknowledgements
• Massey University
• Ann-Marie Jackson
• Professor Don Cleland
• Professor Clive Davies
• The University of Western Ontario• Professor Franco Berruti• Professor Cedric Briens• Dr. Lorenzo Ferrante• Mohammad Latifi• Ran Xu• Rohan Bedmutha• Mike Jacobson
Queen Elizabeth II Technicians’ Study Awards
Shirley and Lukey
27
Thank you
Questions?
John Edwards
School of Engineering and Advanced Technology
Massey University
Palmerston North
email: J.Edwards@massey.ac.nz
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