gasification · a. nordin, et al. (2005). initial review and evaluation of process technologies and...
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Gasification
Prof.dr.ir. Wiebren de Jong (TU Delft, NL; RUG, NL)
Biofuels Summer School
2018
Thursday 21 June 2018
My background
Faculty 3mE, Department of Process & Energy
6 sections:
Energy Technology (prof. Boersma, chair)
Large-Scale Energy storage
Engineering Thermodynamics (prof. Vlugt)
Intensified Reaction and Separation Technology (prof. Stankiewicz)
Aero- and hydrodynamics (prof. Westerweel)
Multi-Phase Systems (prof. Poelma)
https://www.tudelft.nl/en/3me/organisation/organisation/departments/process-energy/
Biomass – what is it?
Definition (EU e.g.) (EU Directive 2009/28/EC):
The biodegradable fraction of products, waste and residues from biological origin from agriculture
(including vegetal and animal substances), forestry, and related industries including fisheries and
aquaculture, as well as the biodegradable fraction of industrial and municipal waste
Oil crops Sugar &starch crops
Lignocellulosic biomass
Biodegradable MSW, Sludges, manures
PhotosyntheticMicroorganisms
So…Biomass is?
Very diverse
Abundantly available
Linked with food/feed/fibre production
Non conventional (comp. to fossil), not an easy ‘plug-in’ energy vector
Requiring:
taylored harvesting/handling (transportation/storage)
widely differing processing technologies to arrive at suitable end products
Biomass utilisation strategy
Sustainability criteria to be met
Direct conversion of local/domestic biomass
(residues) in distributed plants into materials / heat & power
Upgrading of biomass into high-density fuels with favourable
logistic properties (solid: pelletisation,torrefaction;
liquid: pyrolysis; gas: gasification)
Utilizing these biomass fuels targeting triangle of
biomass based economy
Heat utilisation optimisation to achieve maximum
energy efficiency
Pharma &Fine Chemicals
Food & Feed
Chemicals & Materials
Transportation Fuels
Power & Heat
Market Volume
Van Krevelen Diagram depicting Coalification
book ‘Biomass as a sustainable energy source for the future’,Wiley, de Jong and van Ommen, 2015
Molecular Architecture of Wood Tissue
book ‘Biomass as a sustainable energy source for the future’,Wiley, de Jong and van Ommen, 2015
Cellulose
O
O O
OH
HO
OH
O
O
OH
HO
OH
O
OHO
OH
OH
HO
O
OH
OH nCellobiose unit
4 4
4
1
1
1
O
O
O
OH
O
O
O OH
H
O H
H
OHO
Cellulose is a linear
polymer of glucose,
crystalline structure
(some part in biomass
amorphous)
Degree of polymerization
~5000-15000
book ‘Biomass as a sustainable energy source for the future’,Wiley, de Jong and van Ommen, 2015
Hemicellulose(s)
book ‘Biomass as a sustainable energy source for the future’,Wiley, de Jong and van Ommen, 2015
Xylan is the dominant
hemicellulose in hardwood and
non-woody biomass. Amorphous
structure.
Degree of polymerization ~500-
1000
Other Polysaccharide Structures
compared to cellulose
O
OHO
OH
NH2O
OHO
OH
NH2
O
O
OHO
OH
NHOAcO
OHO
OH
NHOAc
O
O
OHO
OH
OH
O
O
OH
HO
OH
O
n
n
n
Chitin
Chitosan
Cellulose
book ‘Biomass as a sustainable energy source for the future’,Wiley, de Jong and van Ommen, 2015
Lignin
(C40H44O6)
• Aromatic
structure
• Binding
agent
book ‘Biomass as a sustainable energy source for the future’,Wiley, de Jong and van Ommen, 2015
Inorganic Matter in High-T Ashes
Vassilev et al. (2010) Fuel 89, pp. 913-33
Biomass conversion technologies
book ‘Biomass as a sustainable energy source for the future’,Wiley, de Jong and van Ommen, 2015
Gasification technologies
A division related to the way of heat input:
Indirect (allothermal)
Heat is introduced by heat exchange (e.g. heatpipes, external reactor wall)
Relatively expensive, limited in temperature
Product gas is not diluted
Direct (autothermal)
Steam/Oxygen/air (in different combinations) added, part of the biomass is combusted to generate heat.
High temperature possible
Product gas is diluted (particularly when using air)
Hybrid concepts
Gasification: process chemistry
Picture gasifier: https://www.ankurscientific.com/technology.html
Schematic: http://www.gasifier.in/faq.html
Gasification: process chemistry
and thermodynamics
Table: Huber, G.W., Iborra, S. and Corma, A. (2006) Chem.Rev. 106, pp. 4044-98
Not only simple small molecules are formed…tars
Small-scale gasifiers: fixed-bed reactors
Olofsson, I., A. Nordin, et al. (2005). Initial Review and Evaluation of Process Technologies and Systems Suitable for Cost-Efficient Medium-Scale Gasification for Biomass to Liquid Fuels. Umeå, Technical Report for University of Umeå, Umeå (Sweden)
Biomass enters in top Air/oxygen in bottomHigh tar content: ca. 100 g/Nm3
Mature technology for heat productionCan be used for small scale applicationsNo carbon in the ash
Biomass enters in top Air/oxygen in toplow tar content: ca. 1 g/Nm3;Ideal when clean gas is requiredLower overall thermal efficiencyDifficulties handling higher moisture and ash contents
Updraft Downdraft Crossdraft
Medium/large-scale: Fluidized bed reactors
Small/medium biomass particles
Air/oxygen in bottom
Biomass in bottom (usually)
Bed contains sand/other bed
material
Good for large scale applications
Medium tar yield (order of magn.
g/Nm3)
High particle loading in gas
Olofsson, I., A. Nordin, et al. (2005). Initial Review and Evaluation of Process Technologies and Systems Suitable for Cost-Efficient Medium-Scale Gasification for Biomass to Liquid Fuels. Umeå, Technical Report for University of Umeå, Umeå (Sweden).
BFB CFB
Hybrid FB
Entrained flow gasifiers
Oxidizer: Oxygen
High T (up to 1700 oC)
Ashes are molten
Developed for coal/oil
Low tar formation
Very small particles needed: pretreatment
Gasification technologies for biomass
and their scales
0.1 MW
1 MW
10 MW
100 MW
1000 MW
Downdraft fixed bed
Updraft fixed bed
BFB (atm./pres.) CFB (atm.)
CFB (pressurized)
Entrained flow
Hybrid FB
Important parameters for gasifier design
2
2
externalO supply/fuelsupply=
stoichiometricO requirement/unit of fuelinput (daf basis) Stoichiometric
Oxygen ratio
steam mass flowSB =
fuel feed rate
Steam toBiomass Ratio
m,C,residue
m,C,feed
CC = 1
CarbonConversion
m,i
m,fuel fuel
LHVCGE =
LHV
i
ColdGasEfficiency
Thermodynamic Equilibrium - gasification
Wood, 20 bar, 850oC Oxidizer: air
Kinetic rates of different biochars
C+H2O=CO + H2 reaction
Di Blasi, C. (2009). "Combustion and gasification rates of lignocellulosic chars." Progress in energy and combustion science 35(2): 121-140.
1 m 1 X
m t 1 X t
Cr
0
0
m mX
m m
t
TGA
Char gasification kinetics
XT c X
t
Xk X c
t
i
i
( , ) ( )
. .
char s
n
dR R
d
de g f
d
Khawam and Flanagan (2006). J.Phys.Chem.B 110(35), pp. 17315-28.
Value chains towards different products
Industrial example: Enerkem (Rotterdam)
gasification of waste to produce methanol
https://enerkem.com/about-us/technology/
Gas cleaning and upgrading steps for biomass
gasification in an industrial BtL chain
UtilizationStorage?
Tar, what is it?
In the end of the nineties (last century) long discussions in scientific community
(a.o. IEA, EU-FP5) ‘ending’ in:
Generic (unspecific) term for entity
of all organic compounds present
in the gasification product gas
excluding gaseous hydrocarbons
(C1 through C6)
What are the issues with tars?
Relatively low temperature gasifiers (FixB, [C]FB) cause tar issues
(next to gasification product gas losses):
Pipe blocking Process Equipment Fouling
ECN, website http://www.thersites.nl/
Methods for reducing tar concentration
levels during biomass gasification
Gas cleaning, particles:- Wet (scrubbers, oil/water)- Dry (cyclones & filters)
Another class of gasification technology:
Supercritical water gasification (SCWG)
• Drastic change in physical
properties of water under near-
critical water conditions
-> opportunity for salt separation
and tar-free gasification
Kamler, J., Andres, J., 2012. in: Yun, Y. (Ed.), Gasification for Practical Applications. InTech.
• Mid 80ies to 90ies: autoclave studies
– Kinetic studies of pure compounds (Antal USA e.g.)
– Blending studies and their impact on carbon conversion,
gas yields etc.
– Impact of reactor wall material on the reactions
(catalysis)
Development of SCWG technology
• Later development of continuously operating reactor technology• Tubular (plug flow) reactors (NL: Sparqle; DE: KIT with salt separation)
• Novel: fluidized bed reactor (China/Japan, NL: Delft/Gensos)
Process Concept SCWG
Matsumura Y., et al. (2005) Biomass Bioenergy;29:269–92.
Reactor
FactSage & SimuSage based model
main components
Case study, work-out in small groups
Waste gasification system, Enerkem BFB gasification technology
Per year:360 kton waste processed,220 kton methanol produced
- How many households (est.)?- What to do with the product?- Which markets?- What are the implications?- Which issues to you foresee in the
process chain? How to tackle?- Better alternatives?