DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Challenges in methanation for biomass based SNG-production

Dipl.-Ing. Thilo Henrich DVGW-Research Station at Engler-Bunte-Institut Gas Technology

GERG Workshop, Session 5, „Other R&D“ Brussels, 5th June 2009

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Structure

•

Motivation

•

Theoretical considerations

•

Monolithic reactors

•

Summary

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Motivation Problems: Finiteness of fossil fuel resources

High anthropogenic greenhouse gas emissions

Possibilities for the gas industry?

Solutions: Improvement and optimisation of energy efficient technologies

Methane from renewables

Biogas

SNG

State of the art

To be developed 3

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Motivation Biogas/ „Biomethane“ Manure Biodegradable waste Energy plants Straw Wood Thermochemical CH4

Fermentation

Upgrading

Low lignin and high water content

High lignin and low water content

Gasification

Gas conditioning

Methanation

Upgrading

Advantages of the thermo-chemical way: • Decoupling of production and consumption • Utilisation of non-fermentable biomass • SNG directly usable as biogenic fuel (CNG) • Adaptation of known coal technology possible • High energetic efficiency

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Motivation

Power generation by steam turbine

Efficiencies: Electricity (25 %)

Biomass (100 %)

Combustion (ηKW = 85 %)

Available heat (85 %)

Steam turbine (ηel = 29 %)

Waste Heat (60 %)

SNGproduction

Power generation by gasification

Waste heat (15 %)

Electricity (25 %)

Biomass (100 %)

Gasification (ηKG = 72 %)

Clean synthesis gas (72 %)

Gasengine (ηel = 35 %)

Waste Heat (47 %)

Waste heat (28 %)

Biomass (100 %)

Gasification (ηKG = 72 %)

Clean synthesis gas (72 %)

Conditioning (η = 83 %)

SNG (60 %)

Waste Heat (12 %) Waste heat (28 %)

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The total efficiency depends on the recovery of the waste heat

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

SNG-production from coal

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Motivation Great Plains Gasification Plant Coal mine Power plant

Synfuel Plant 7

Motivation

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

• Up to now the only commercially operated plant for SNG-production • Byproducts: Carbon dioxide, ammonia, ammonia sulphate, phenol, cresylic acid

2 GWth

Source: J.M. Panek, J. Grasser, Report, US DOE, (2006)

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Theoretical considerations for methanation

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Theroretical considerations

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

From the new feedstock wood new boundary conditions arise:

• Coal is produced centrally ◄► Wood is produced decentrally • Limited wood availability demands highly efficient technologies • For wood as a natural product a sustainable wood economy has to be established • Wood gasification plants have to be smaller than coal gasification plants

A process development for the feedstock wood for plants up to 100 MW (thermal) is necessary

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Theroretical considerations Process based on the gasification of wood:

Raw gas

Dust removal

Synthesis gas cleaning

CO-Shift

Methanation

• Alkali metals • Tars • Adjustment of • CH4production • Halogens • Sour gases the H2/COratio • Heavy metals

Gas pipeline

Compression to injection pressure

SNG conditioning

• CO2-removal • Drying • (Adjustment of the heating value)

Catalytic process steps 11

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Theroretical considerations Reactions involved in methanation: • CO-Methanation:

CO + 3 H2

CH4 + H2O

• CO2-Methanation:

CO2 + 4 H2

CH4 + 2 H2O

• WGS-Shift:

H2O + CO

CO2 + H2

• Boudouard-reaction:

2 CO

CO2 + C (s)

Properties of the methanation reaction: • Highly exothermic: Formation of methane favoured at low temperatures • Decrease in mole-number: An increase in pressure results in a higher methane-yield • A slight excess in hydrogen and addition of water prevents carbon deposition from the gas phase • Methanation of carbon dioxide only takes place at low CO-partial pressures 12

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Theroretical considerations Thermodynamics of methanation:

Methanation of synthesis gas (allothermic fluidised bed gasification with water): 1.2

Educt gas (dry): CO: 14 vol.-% CO2: 27 vol.-% H 2: 45 vol.-% CH4: 9 vol.-% C3H8: 4 vol.-% N2: 1 vol.-%

CO-conversion XCO

1

0.8

0.6 p = 1 bar 0.4

p = 10 bar p = 50 bar

0.2

p = 100 bar

Aspired temperature range 0 200

300

400

500

600

700

800

Temperature T in °C

Temperature range is restricted! Only small support of methane yield at elevated pressure!

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Theroretical considerations

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Reactor types that have already been successfully used in methanation: Fluidised bed reactors • Offer the advantage of a very intensive heat- and mass transfer; therefore an almost isothermal mode of operation is possible • Disadvantageous is the abrasion of the fluidised bed material, which has an adverse effect on the performance of the fluidised bed • Currently the PSI focuses on methanation in fluidised beds (PSI: PaulScherrer-Institut, Villigen, CH) Fixed bed reactors: • Offer the advantage of established construction technology (but expensive) • Of adverse effect are the poor heat transfer properties  formation of hot spots  thermal stress  degradation of the catalyst • Currently the ZSW focuses on the Fixed-bed-methanation („Zentrum für Sonnenenergie und Wasserstoff-Forschung“, Stuttgart, FRG) 14

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Monolithic reactors

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Monolithic reactors General design: • A system of parallel, catalyst-coated channels

Application-areas for monoliths: • Exhaust emission control • Automotive flue gas cleaning

Further application-areas: • Strongly endo- or exothermic reactions • Flue gas conditioning in the decentralised energy supply by fuel cells • Reforming

200 cpsi1)

400 cpsi

16 1) Channels

per square inch

Monolithic reactors

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Special case: Metallic monoliths Advantages: • High radial heat conductivity  An homogeneous temperature profile  Less hot spots  Longer catalyst lifetime • Low abrasion of the catalyst • Low pressure drop • Adjustable geometric parameters • Numerous reactor concepts can be realised

Challenges: • Development of a efficient reactor cooling concept • Coating of the monolith with the catalyst • Reactor design and industrial production • Choice of the monolith material 17

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Monolithic reactors

Influence of the material on the maximum reactor diameter: 360 Requirements: Tmax(r = 0) = 350 °C (623 K) Taussen (r = R) = 200 °C (473 K)

340

Temperature T in °C

320

300

280

260

Al2O3-Fixed Bed λeff,rad = 8 W/(m K) ► rmax = 26 mm

240

Stainless Steel λeff,rad = 10 W/(m K) ► rmax = 29 mm

Aluminium λeff,rad = 96 W/(m K) ► rmax = 89 mm

220

200 0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Radius r in m

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Monolithic reactors

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Estimation of the reactor size Initial point for calculations: • Gasification of wood with steam in a fluidised bed • Power of the gasifier: 10 MW (thermal) • Methanation reactor: Metallic monolith coated with a Ni- Educt catalyst (Materials: Steel, Aluminium) Mass- & Heat streams: • Educts stream: ≅ 9650 m3/h (1 bar, 300 °C) • Thermal power of the reactor: ≅ 1.5 MW

Hot cooling medium

Product

Cold cooling medium

Monolith: • Residence time in the reactor: ≅ 0.5 s • Number of channels: 1.2 x 106 • Radial heat conductivity: kSt = 2 W/(m K) kAl = 16 W/(m K) • Maximum reactor diameter: dSt = 48 mm dAl = 144 mm Methanation reactor: • Reaction volume: ≅ 1.35 m3 • Number of parallel monoliths: Steel ~ 3420, Aluminium ~ 380

source.: www.olaer.cz

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Summary

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

• SNG-production is an interesting way for the gas industry to produce gaseous fuels • Wood/lignin-rich biomass is a promising feedstock, which is not used for SNG-production up to now • The methanation of a clean synthesis gas is an established process for the feedstock coal • The methanation can be carried out at low temperatures with a high CO-conversion • The monolith material can enhance the heat transfer properties significantly, which simplifies the reactor design

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Thank you for your attention! Do you have questions?

Dipl.-Ing. Thilo Henrich Phone: +49721/608-2693; Email: [email protected]

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Gesamtprozess Vergasertypen Festbett Partikelgröße: < 400 mm Betriebstemperatur: < 1000 °C Betriebsdruck: beliebig Anlagengröße: < 10 MWth

Syntheserohgas Vergasungsmedium

Vergasungsmedium

Syntheserohgas Syntheserohgas

Syntheserohgas

Zyklon

Brennstoff

Brennstoff

Vergasungs-/ Fluidisierungsmedium

Brennstoff

Brennstoff

Wirbelschicht Partikelgröße: < 50 mm Betriebstemperatur: < 800 °C Betriebsdruck: beliebig Anlagengröße: 10 - 100 MWth Hoher Methananteil im Synthesegas möglich!

Vergasungs-/ Fluidisierungsmedium

Flugstrom Partikelgröße: < 100 µm Betriebstemperatur: > 1000 °C Betriebsdruck: beliebig Anlagengröße: 100 - 1000 MWth

Brennstoff

Vergasungsmedium Syntheserohgas

Schlacke

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Methanisierung

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Katalysatoren Katalytisch aktiv sind: Elemente der VIII. Nebengruppe (sog. Eisen- und Platingruppe) sowie Silber und Molybdän Aktivitäts-Reihenfolge: Selektivität zu CH4: Preis pro kg (roh):

Ru > Fe > Ni > Co > Rh > Pd > Pt > Ir Pd > Pt > Ir > Ni > Rh > Co > Fe > Ru Rh > Pt > Pd > Ir > Ru > Co > Ni > Fe

Nickel ist der beste Kompromiss bezüglich Aktivität, Selektivität und Preis, stellt aber hohe Anforderungen an die Reinheit des Synthesegases (bezüglich Halogenund Schwefelverbindungen), Gefahr der Nickelcarbonyl-Bildung bei Temperaturen < 250 °C Stand: 13. März 2008

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DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Wärmeübertragung Berechung der radialen Wärmeleitfähigkeit Λr Λ r λ s Pe d = + λf λf K'

Ansatz Festbett1): Angaben:

λf = 0,176 W/(m K); Wärmeleitfähigkeit des Fluids λs = 8 W/(m K); Wärmeleitfähigkeit des Feststoffes (Al2O3) Ped = 0,8; Peclet-Zahl K´ = 7,12; Konstante

Ansatz Metallische Wabe2):   ε+ξ − ε + Λr = λ s  1− ε + ξ +  λw λw 1 1 − ε + ξ + ε + ξ − ε + ξ +  λs λs 

(

Angaben:

)

(

)

(

)

(

ε

)

ε+ξ − ε +

λf λs

    ε 

−1

λS = 25; 236; 401 W/(m K); Wärmeleitfähigkeit des Wabenmaterials (Edelstahl1), Aluminium1), Kupfer1)) ε = 0,473); Leerraumanteil der metallischen Wabe ζ = 0; Porosität des Katalysatorträgers (Anmerkung: kein Washcoat)

2) G. Groppi, E. Tronconi, Catalysis Today, 69, 63-73, (2001) VDI-Wärmeatlas 3) X. Huang, Studienarbeit, Engler-Bunte-Insititut, Universität Karlsruhe (TH), 2006 1)

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SNG-Erzeugung in der TBM

Holzvergasung

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Ziel: Selektive CO-Methanisierung bei nahezu atmosphärischem Druck zur SNG-Erzeugung in metallischen Wabenreaktoren

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SNG-Erzeugung in der TBM

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Förderung durch die Landesstiftung Baden-Württemberg Verbundpartner: • ZSW, Stuttgart • DVGW-Forschungsstelle, Gastechnologie Zielsetzung:

„Energetisch effiziente Bereitstellung eines einspeisefähigen Erdgassubstitutes auf Basis der Vergasung von Biomasse“

Förderzeitraum:

3 Jahre

EBI/DVGW:

• Katalysatorauswahl für Methanisierung • Laborversuche zur Methanisierung in metallischen Wabenreaktoren • Erstellung eines Verfahrenskonzeptes unter Einbindung der metallischen Wabenreaktoren • Methanisierungsversuche mit Gas aus der Holzvergasungsanlage der Technologieplattform Bioenergie und Methan 26

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Known processes

Due to the energy crises in the 1970s numerous processes for SNG-production on basis of the gasification of coal or refinery residues have been developed Name/ Develo per

ADAM & EVA

ConoMeth/ SuperMeth

CRG

Gassynthan

Hygas

Lurgi

TREMP

BiGas

Comflux

IRMA

Chem Systems

Reactor -type

FB

FB

FB

FB

FB

FB

FB

WS

WS

RBWÜ

Bubblecolumn

stages

3

2

2

2

2

2

3

1

1

1

1

Status of develop ment

Pilot

Demo/ Pilot

n.s.

n.s.

Pilot

Com m.

Pilot

Pilot

Pilot

Pilot

Technikum

pressur e (in bar)

30

≤ 80

~ 25

40 – 50

70

30

30

86

20 – 60

30

~ 70

Temperature (in °C)

250 – 300

n.s.

300

300

450

~ 450

300

k.A.

400 – 500

270

~ 340

FB: Fixed Bed, FLB: Fluidised Bed, RB-WÜ: Rohrbündelwärmeübertrager

In most instances adiabatic, multi-stage fixed bed-reactors have been used 27

DVGW-Research Station at Engler-Bunte-Institut, Universität Karlsruhe (TH) Gas Technology

Wärmeübertragung

Radiale Wärmeleitfähigkeit Λr

Einfluss des Materials und der Geometrie auf Λr

Wabe: ε = 0,47

Schüttung aus Al2O3 mit ε = 0,42

Hohlraumanteil ε

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