Syngas from Biomass Problems and Solutions en route to ... · Forschungszentrum Karlsruhe in der...
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Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Syngas from BiomassProblems and Solutions en route to
technical Realisation
International Conference
„Synthesis Gas Chemistry“
Dresden, 4.-6. October 2006
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Motivation
Biomass is the only renewable carbon source!
Biomass should be used favourably for organic chemicals and fuel production instead of electrical power and heat generation!
Syngas and its main constituent, Hydrogen, are key intermediates for synthetic chemistry!
Synthetic fuels are most promising products!
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Main uses of syngas and hydrogen
CO + H2 Methanol
Hydrogen
HydrocarbonsWaxes
AldehydesAlcohols
AmmoniaBiologicaldirect and via intermediates
Thermochemicalvia intermediates
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Fuel options of syngas and hydrogen
CO + H2Methanol
DME
Hydrogen
Medium BTU gas
GasolineDiesel
Fuel Cells
Gasoline
MTBE
CH4 (SNG)
I. Wender, Fuel Proc. Techn. 48 (1996) 189
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Thermochemical gas formation from biomass
Dry Biomass
WetBiomass
H2, CH4
CO, H2
C6H12O6 → 6 CO + 6 H2
6 CO + 6 H2O → 6 CO2 + 6 H2
C6H12O6 + 6 H2O → 6 CO2 + 12 H2
Fuell cells
Gas engines
......
Fischer-Tropsch
Methanol
DME .....
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Gasification of dry biomass
DryBiomass
CO, H2
C6H12O6 → 6 CO + 6 H2
6 CO + 6 H2O → 6 CO2 + 6 H2
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Hurdles in biomass utilization
Usually low volumetric energy density
Widely distributed occurrence
Heterogeneous solid fuels
High ash and salt contents
Direct gasification is problematic (tar and methane formation)
Unfavourable H2:CO ratio after gasification
Downstream syntheses require high pressures (Fischer-Tropsch ≈ 30 bar, Methanol, DME ≈ 80 bar)
Use of catalysts sensitive to impurities
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
The slurry gasification concept
regionale Pyrolyse- Anlagen
ZentralerCentral syngas and fuel
production
25 km
Regional intermediate fuel production
250 km
Transport radiusEnergy density [GJ/m3]
Straw 1,5
Slurry 20
Diesel 36
Distributed biomass
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
The process chainbasing on a review an
technologies suitable to be adapted to biomass
feedstocks
Stroh
Synfuel
Fast pyrolysis
Gas conditioning
High pressure entrainedflow gasification
Fuel synthesis
Slurry preparation
Straw De-central
central
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Fast pyrolysis using a twin screw mixer reactor
M
HeizerSandkreislauf
M
Stroh, Heu u.a.
Häcksler
Kühler
Doppelschnecken-Reaktor
kalte
s St
rohh
äcks
el
heis
serS
and
ca. 5
00 °C
Pyrolysekoks
Pyroly segas
Pyrolyseöl
Slurry
M
HeizerSandkreislauf
M
Stroh, Heu u.a.
Häcksler
Kühler
Doppelschnecken-Reaktor
kalte
s St
rohh
äcks
el
heis
serS
and
ca. 5
00 °C
Pyrolysekoks
Pyroly segas
Pyrolyseöl
Slurry
Pyrolysis oil
Pyrolysis char
Straw, wood, ....
Pyrolysis gas
Twin screw mixer reactor
Heater,Heat carrier loop
CoolerSlurry
Chopper
Cold chopped straw
Hot sand 550°C
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Reactor principle
Gases, vapors and pulverised
hotsandhotsand Sand loop
Straw-cutratio 5-15
Sand
Char
Mechanically fluidised sand at 500°C (no dilution by gas),
fast transport with good radial mixing (2 s gas retention time)
fast heat transfer, „ball milling“ effect
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Straw retention in the mixing reactor
0
0,05
0,1
0,15
0,2
0,25
0 20 40 60 80 100
t (s)
Mass distribution
5
4
3
21 Hertz
90 kg Sand pro hplus 3 g Stohhäcksel
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Variation of heat transfer carriers
Steel SiC SiO2 cp,WT (at 600°C) [kJ/(kg·K)] 0,6 1,2 1,25
(Taus-Tein)WT [K] 50 100 50 100 50 100 mWT/mBio (wet) [ - ] 50 25 25 12,5 24 12 mWT/mBio (dry) [ - ] 43 22 22 11 21 10
Optimisation of the heat transfer medium for:
- spherical particles → reduced abrasion of the medium- higher heat capacity → low heat carrier / biomass ratio- coarse-grained particles → better milling of the char and its separation from the heat carrier medium
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Representative results
Focus on more „difficult“ biomass like straw
less condensates, more ash (solids)Lab scale plant (10 kg/h)
1 2 3 4 5 6 7 80
200
400
600
800
1000
Pro
dukt
ausb
eute
g/k
g
Material Nr.
Gas Schwelteer Schwelwasser Koks
Wood Straw
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
porosity50 - 80 %
charparticle
volumefraction
~ 50 %porosity
50 - 80 %
charparticle
volumefraction
~ 50 %
Slurry preparation
Highly porous char from straw, soaked with 78 wt.% tar Is liquefied by milling and heating
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Better milling with increasing viscosity and particle content
Influence of milling on slurry preparation
Original char particles suspended in alcohol
Char particles after colloidal milling
Slurry 1: 21 wt.% weat straw charSlurry 4: 40 wt.% weat straw char
Suitable for entrained flow gasification
Particle size / μm
Mas
s di
strib
utio
n
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2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7
-3
-2
-1
0
1
2
3
460 50 40 30 20 -- -- --
0,1
10
1,0
temperature [ o C ]
33 % char
30 % char26 % char
23 % char visc
osity
[ Pas
]
loga
rithm
of v
isco
sity
[ ln
( η) ]
reciprocal temperature [ 1000/Kelvin ]2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7
-3
-2
-1
0
1
2
3
4 60 50 40 30 20 -- -- --
0,1
10
1,0
Temperature[ o C ]
33 % char
30 % char26 % Koks
23 % char Visc
osity
[ Pas
]
Visc
osity
ln(η)
Reciprocal temperature [ 1000/Kelvin ]
Viscosity of slurrys
with high particle load near the sedimentation limit: a few Pasgood atomization below 0.3 Pas
Pre-condition: Enough liquid phase to cover all particles with a liquid film
Short storage: rearrangement of the organic molecules after mixing:→ increase of viscosity.
Long time storage: char particles improve their arrangement, less liquid is contained in the space between the particles, → decrease of viscosity.
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Continuous slurry preparation
Continuously operated slurry mixer (1 t/h) at FZK
Supply of pyrolysis oil (8 t) and char (4 t) at Future Energy
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Tar free synthesis gas
Suitable for feeds rich of ash
Gasification with pure O2
High pressures, 30 to 100 bar
Temperatures around 1200°C
Residence time of seconds,complete C-conversion
4 gasification campaigns withdifferent feed materials, process parameters,500 kg/h (2-3 MWth)
High pressure entrained flow (GSP) – gasifier
pilot flameoxygenfuel
steel pressure shell
raw syngasmolten slag
~ 1200 °C ~ 50 bar
water cooledradiation screen
pilot flameoxygenfuel
pressure shell
raw syngasmolten slag
~ 1200 °C ~ 50 bar
water cooledradiation screen
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Results of slurry-gasification
H2
CO
CO2
N2
Gas composition
• no tar, < 0.1 vol.% methane• C-conversion ≥ 99 %• operation without problems
• Equilibrium:(CO2 • H2) / (CO • H2O) = K(T)
• Slag melting point < 1200 °C
Feeds:Solids: 0 – 39 wt.%Ash: 3 %Heating value: 10 – 25 MJ/kgDensity: 1250 kg/m3
Operation conditions:Throughput: 0.35 – 0.5 t/hPressure: 26 barTemperature: 1200 – 1600 °CFeed-Temperature: 40, 80 °C
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Influence of the water content
79-1
78-1
62-1/2
0 20 40 60 80 100
H2 CO CO2 N2
Vers
uch
Nr.
Gasausbeute / Vol.%
50.6
27.8
5.8
H20 %
441359090,5
571686092
702450095
ηHHV kJ/kg
Conver-sion %
No tar, < 0,05 Vol.% Methane, 0.5 t/h1200 – 1300°C, 24 MPa, 25 – 33 % char
* Gasifcation campaigns 2003 and 2005Gas yield / vol.%
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Energy- and mass balance
7.5 t Wood or Straw with 15 wt.% H2O
5.4 t Condensate/char - slurry plus ~ 1,8 t O2
1.2 t FTS-raw products
1 t Synthetic fuel
~ 40 % C 5+ FTS - ProdukteSynfuel ...
~ 5 % valuableC5-products
Lignocellulose 100 %
Schnellpyrolyse ~ 3 %
Kondensat/Koks – Slurry ~ 90 %
Flugstrom -Druckvergasung ~ 3 %
~ 13 %
ReaktionswärmeSynthese -Rohgas Synthese -Reingas
~ 76 %
FT- Synthese
FTS - Reaktionswärme
~ 18 %
~ 6 %
~ 5 %
nicht umgesetztes SyngasSyntheseprodukte
~ 51 %
~ 1 %
~ 1 %
~ 1 %
C5- - ProdukteTrennung
Lignocellulose 100 %
Fast pyrolysis~ 7 %
~ 3 %
Condensate/char – Slurry~ 90 %
Entrained -flow gasification ~ 3 %
~ 13 %
Heat of reactionSynthesis-raw gasSynthesis-clean gas
~ 76 %
FT- Synthesis
Heat of reaction
~ 18 %
~ 6 %
~ 5 %
Not converted SyngasSynthesis products
~ 51 %
~ 40 % C 5+ FTS - ProdukteSynfuel, waxes, olefines...
El. Power and HT steam:
~ 42 %Heat losses:Sum ~ 6 %
~ 1 %
~ 1 %
~ 1 %
C5 - Products
C5
Separation
By-products:Chemicals, Steam, Electricity
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Fundamental studies in lab scale equipment, parameter determination for various feed materials and conditions, selection of appropriate process technologies
Demonstration of the principal technical feasibility in technical relevant plants, process variants in bench scale plants
Construction and operation of a pilot plant proving practicability, allowing for scale-up and reliable cost estimates
State of development
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Stepwise construction :
1. Biomass conditioningFast pyrolysis, slurry preparation 2006
2. Gasifier 2007
3. Gas conditioning Fuel synthesis 2008
Pilot plant (500 kg/h)
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
State of construction
Conditioning Slurry mixing
Pyrolysis plant
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Gasification of wet biomass
WetBiomass
H2, CH4
C6H12O6 + 6 H2O → 6 CO2 + 12 H2
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Hydrothermal gasification of biomass
is an option to generate hydrogen directly from wet biomass and organic residues using a renewable resource
could fill the lack in hydrogen as present in the dry biomass conversion process, because for methanol production a CO/H2of 2 is required
is favourable, when “zero” costresidual biomass or waste are used
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Syngas composition after gasification 2 CO + H2 → H2-deficit
Hydrogen from single gasification process:CO + H2O → H2 + CO2 Shift-reactionCO + 2 H2 → H2O + -CH2- Synthesis2 CO + H2 → CO2 + -CH2-1t product -CH2- from 4.2 t product gas⇒ bad carbon efficiency
External hydrogen, e.g. by hydrothermal gasification of e.g. bio-ethanolC2H5OH + 3 H2O → 6 H2 + 2 CO2C2H5OH + H2O → CH4 + CO2 + 2 H2 (H2:CH4 = 4:1)1 t Hydrogen from 7.5 t ethanol
C2H5OH + 2 (2 CO +H2) → 2 CO2 + H2O + 4-CH2-1 t Product from 2.1 t product gas and 3.2 ethanol⇒ higher carbon yield in the fuel⇒ no need for CO2-separation
Hydrogen for synfuel production
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Hydrothermal gasification of biomass
ΔrHo = 158 kJ/mol (Glucose)
C6H12O6 → 6 CO + 6 H2
6 CO + 6 H2O → 6 CO2 + 6 H2
C6H12O6 + 6 H2O → 6 CO2 + 12 H2
Classical gasificationWater-gas-shift-reactionHydrothermal gasification
• No drying prior to the process
• High H2-yield obtained under pressure, nearly no COintegrated water gas shift reaction, catalysts included
• Short reaction times, high space/time-yields
• No tar and char under optimal conditions due to solvation of the reaction intermediates, solvent like environment
• Easy CO2-separation under pressure
• Inorganic components are not volatile
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What thermodynamics predict?
Wood, CH1,44O0,66, 25 MPa, 10 wt.%
300 400 500 6000
1020304050
H2
CO
CO2
CH4
T / °C
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Process technology• High pressure feeding and pre-treatment• Handling of solids precipitations• Adaptation to different feed stocks and products• Experience with real feed stocksby operation of the pilot plant VERENA and special test facilities
Process fundamentals for reaction engineering and optimization• Optimisation of H2-yield• Optimisation of H2 / CH4 ratio• Avoidance and reduction of tar formationby identification of main reaction pathways and their dependencies via key components
R&D demand
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Reactor35 L Volume
0,11 m i.D., 3,7 m lengthInconel Ni-Alloy
External HeatingFeeding100 kg / h 5-20 % dmc
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Biomass Water
Feed
Colloidal mill
HP-Pump
ReaktorPre-heater
Economizer
Cooler
Separator
CO2-Scrubber
Res. Water tank
Gas tank
Test facility VERENA
Feed section Reaction section Separation section
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Hydrothermal gasification of maize silageResults before and after CO2-separation
7.5 wt.% DS, 700 °C, 250 bar, 1.3 – 3.4 min, Avarage from 7 independent test runs
CO244%
H228%
CH422%
C2H65%
CO1%
H251%
CH439%
C2H68%
CO2%
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Hydrothermal gasification of maize silage
.5 wt.% DS 00 °C, 250 bar .3 – 3.4 min
CO244%
H228%
CH422%
C2H65%
CO1% H2
51%CH439%
C2H68%
CO2%
After CO2–separation
Before CO2–separation
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Tumbling reactor (Batch)
500°C, 50 MPa, 1 L
Tubular reactor
600°C, 30 MPa, ca. 20 ml
Cont. Stirred tank reactor
600°C, 100 MPa, 190 ml
Lab scale plantsexhibiting different reactor characteristics,
model compounds and biomass
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1 2 3 4 5 620
25
30
35
Gas
yie
ld /
(mol
/kg)
τ / min
CO2
CO
CH4
H2
0%
15%
47%
38%
CO2
CH4
H2
0.17%
15%
40%
45%
Gas yield and gas composition - Glucose vs. biomass
Ca. 5% DM, 500°C, 30 MPa;0.5 % (g/g) K2CO3
Phytomass
Glucose / K2CO3
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
020406080
Vol.-
%
CH4 CO2 H2 CO
Gas component
Mit KHCO3Ohne
dd
Influence of alkali salts
25 MPa, 400°C
1,5 % (g/g) Glucose; 0,2 % (g/g) KHCO3
0
50
100
150
200
250
300
350
Con
zent
ratio
n / (
mg/
l)
HMF FU MFFurfurals
Mit KHCO3ohne KHCO3with KHCO3
without
O CHOHOH2C O CHO O CHOH3C
with KHCO3without
O
CH2OH
OH
OH
OH
OH
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Concluding remarks
Both, dry and wet biomass can be utilized for syngas and hydrogen production by technical feasible and economical ways
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Product gas85 kW th:
H2 90 %CH4 6 % CO 4 %
(after CO2-separation)
El. Energy 2 kWe
Feed:15 % MeOH95 kg/h(79 kWth) Losses
(≈ 26 kW)
(Tmax 166 °C, 40 °C reflux )11 kWth
41 kWth
Energy balanceEnergy-
productionEnergy demand
Warm water
15 wt.% methanol, 95 kg/h, reaction temperature = 571 °C, yield 98.4 %, mass balance 98 %
El. power for CO2 scrubbing
3-6
kWe
44 kWth
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0
20
40
60
80
100
120
0 5 10 15 20 25c(CH3OH) / wt %
Ener
gy /
time
(kW
)
LHV/time (gas)
LHV / time (CH3OH)
Heat dissipation (flue gas)
consumption
educt
product
Energy consumption vs. production
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Feed materials for hydrothermal gasification
Use of complete plantWithout catalystWet / toxicWet
Suitable ground and aquatic fresh plantsCorn silageMash (bio-
ethanol)Sludge (biogas)
Bio-alcoholRape oilMeOH
Hydrocarbons
Pyrolysis oil
Paper & cellulosePharmaceutical & chemical industry Biotechnology Sewage sludge
Food &beverage
Wine trashAgricultural production
Liquid manure
Enduring energyDecentralized Energy
Disposal& energy
Disposal& energy
Energy plantsFuelsOrganic
wasteResidual biomass
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
State of development
Fundamental studies in lab scale devices (reaction mechanism, kinetics, catalytic effects by salts contained in the biomass), parameter studies (influence of composition, temperature, pressure, concentration, heating rate), investigation of reactor materials…
Pilot plant operation (100 kg/h) for further process development, e.g. in regard to solids handling (precipitating salts and minerals)and corrosion, optimization in regard to H2/CH4 ratio, operational reliability, and economics
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Concluding remarks
For syngas production from biomass to large extent, thermochemicalprocesses adapted from fossil fuel treatment are well suited,operational practicability and economics have to be proved
Biomass as the only carbon containing renewable energy preferentiallyshould be used for the production of fuels and organic chemicals (consuming ca. 10 % of the primary energy). Heat and electrical power can be produced from other renewable energy sources
Since C/H-ratio available from biomass is worse than that from fossil fuels, additional hydrogen should be produced from other renewable resources
Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft
Financing
R&D budget of Forschungszentrum Karlsruhe
Supplementary support by HGF
Ministerium für Ernährung und ländlichen RaumBaden-Württemberg MELR
Ministerium für Verbraucherschutz, Ernährung und Landwirtschaft BMVEL und FNR
EU-Commission
Federal Ministryof Educationand Research