Syngas from Biomass Problems and Solutions en route to ... · Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Syngas from Biomass Problems and Solutions en route to technical

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


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!


Main uses of syngas and hydrogen

CO + H2 Methanol

Hydrogen

HydrocarbonsWaxes

AldehydesAlcohols

AmmoniaBiologicaldirect and via intermediates

Thermochemicalvia intermediates


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


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 .....


Gasification of dry biomass

DryBiomass

CO, H2

C6H12O6 → 6 CO + 6 H2

6 CO + 6 H2O → 6 CO2 + 6 H2


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


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


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


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


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


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


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



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


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


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


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.


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


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



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


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.%


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


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


Stepwise construction :

1. Biomass conditioningFast pyrolysis, slurry preparation 2006

2. Gasifier 2007

3. Gas conditioning Fuel synthesis 2008

Pilot plant (500 kg/h)


State of construction

Conditioning Slurry mixing

Pyrolysis plant


Gasification of wet biomass

WetBiomass

H2, CH4

C6H12O6 + 6 H2O → 6 CO2 + 12 H2


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


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


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


What thermodynamics predict?

Wood, CH1,44O0,66, 25 MPa, 10 wt.%

300 400 500 6000

1020304050

H2

CO

CO2

CH4

T / °C


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


Reactor35 L Volume

0,11 m i.D., 3,7 m lengthInconel Ni-Alloy

External HeatingFeeding100 kg / h 5-20 % dmc


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


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%


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


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


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


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


Concluding remarks

Both, dry and wet biomass can be utilized for syngas and hydrogen production by technical feasible and economical ways


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


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


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


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


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


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

Documents

Syngas from Biomass Problems and Solutions en route to ... · Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft Syngas from Biomass Problems and Solutions en route to technical