Prof. Dr. techn. G. Scheffknecht

Institute of Combustion and Power Plant Technology

Steam gasification with in-situ CO2 capture

for the production of synthetic fuels

Daniel Schweitzer,

Max Schmid, Marcel Beirow,

Reinhold Spörl, Günter Scheffknecht

8th International Freiberg Conference on IGCC and XtL Technologies, June 12-16, 2016

Institute of Combustion and Power Plant

Technology

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Processes: CFB solid fuel combustion

Flameless combustion

Gasification

CCS

Process technologies: Fluidized bed systems at

different scales

Entrained flow reactors

Measurement technologies: Tar (online)

Standard flue gas

components

Fuels: Solid fossil

Solid and liquid biogenic

Residual

Process Modelling: Process and Reactor

models

CFD simulations

Aspen Plus®

3

Fluidised bed gasification infrastructure

Fluidised Bed Gasification

Air gasification

Steam/Oxygen gasification

Steam gasification

Sorption enhanced reforming (SER)

Two stage SER gasification

Fuels

Biomass

Waste

Lignite

Measurement techniques

Tar: wet chemical acc. tar protocol

Non-condensable gases: online

Non-condensable HC: GC

H2S, NH3, HCl: wet chemical

Online Tar analysis

200 kWth. DFB Pilot

Facility 20 kWth electrically heated

DFB System

5 kWth electrically heated

FB batch System

• Steam gasification is an atmospheric allothermal gasification process

where the necessary heat for the endothermic gasification is provided by

circulating bed material

Bed material (e.g. silica sand) acts as heat carrier

Steam Gasification

Steam Gasification Process

4

• SER (Sorption Enhanced Reforming) is an atmospheric steam gasification

process with in-situ CO2 capture

• Limestone shifts the CO2 from the gasifier to the regenerator

Limestone as a bed material leads to a CO2 lean product gas

Steam Gasification SER Gasification

SER Gasification Process

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• In Oxy-SER process the regeneration is operated under Oxy-fuel

conditions:

• High CO2 output concentrations of >90 vol-%dry in the Regenerator can be

achieved

Possible pre-combustion CCS technology

Steam Gasification Oxy-SER Gasification

Oxy-SER steam gasification

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SER steam gasification

• Due to the chemical equilibrium, the CO2-capture decreases with

increasing gasification temperature

• Limestone bed material acts as

• heat carrier

• CO2 carrier

• catalyser for increasing the gas yield

• catalyser for tar reforming

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0.1%

1.0%

10.0%

100.0%

600 700 800 900

CO

2 c

on

ce

ntr

atio

n in

vo

l-%

Temperature in °C

carbonation CaO+CO2⇀CaCO3

calcination CaCO3⇀CaO+CO2

Regenerator

SER- gasifier

p=1bar

Synthesis

SER gasification: Application

H2-rich

syngas

Purge

CaO (+CaSO4)

Hydrogen

Fuels

Chemicals

Cement

production

Limestone (CaCO3)

CO2 /

flue gas

Heat

Gas

Conditioning

Gas

Conditioning (CO2 storage) O2 / Air

biomass lignite waste

G 2 steam / ORC

process CaCO3

Char CaO

Oxy-SER

Gasifier T=600 - 720°C

Regenerator T=850-950°C

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Oxy-SER gasification:

• Flexibility (feedstock, syngas composition,

air/oxy operation mode)

• In-situ CO2 capture possible

Steam

• Gasifier: bubbling bed reactor

diameter: 0.33 m

height: 6 m

• Regenerator: circulating fluidized bed

diameter: 0.21 m

height: 10 m

• Gas analyses:

Gasifier:

H2, O2, CO, CO2, CH4, C2-C4, tar

Regenerator:

CO, O2, CO2, SO2, NOx

• No electrical heating

• 4 gravimetric feeders for different solid

fuels and additives

200 kWth experimental DFB test facility

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Gasifier H2 rich syngas

Tertiary

+ O2

Secondary

+ O2

Fuel

Steam

Primary

+ O2

CaCO3 & Char

CaO

Regenerator CO2 rich fluegas

• Stable plant operation over several hours

• After ~5h the Regenerator was switched to Oxy-SER mode

Smooth switch of the regenerator to oxy-mode

Demonstration (200 kWth) of the Oxy-SER process

10

0

20

40

60

80

100

0

200

400

600

800

1000

0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00

ga

s c

om

po

sit

ion

in

vo

l-%

dry

Te

mp

era

ture

in

°C

time in h

Temperature Regenerator Temperature Gasifier H2 Gasifier CO2 Regenerator

SER gasification Oxy-SER gasification

Regenerator: - Oxy-SER increases CO2 concentrations (up to > 80 vol.-%dry)

- Oxy-SER has minimal impact on regenerator temperature

Gasifier: - Gasifier operation not affected by regenerator operation mode

- Temperature and gas composition in gasifier constant

Demonstration (200 kWth) of the Oxy-SER process

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0

20

40

60

80

100

0

200

400

600

800

1000

0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00

ga

s c

om

po

sit

ion

in

vo

l-%

dry

Te

mp

era

ture

in

°C

time in h

Temperature Regenerator Temperature Gasifier H2 Gasifier CO2 Regenerator

SER gasification Oxy-SER gasification

• In steam gasification the fuel-C is distributed between:

• C in Syngas (CO, CO2, CH4, C2-C4)

• C in Tars

• C in Char

• C in Carbonate (only for SER process)

• SER produces a CO2 lean product gas

C/H stoichiometry suitable for synthesis

• Oxy-SER regenerator produces almost pure CO2 for storage/utilization

0%

20%

40%

60%

80%

100%

Oxy-SER steam gasification

Syn

ga

s C

om

po

sit

ion

in

vo

l-%

dry

CO2

C2-C4

CH4

CO

H2

TGasifier: 660°C bed material: CaO

TGasifier: 800°C bed material: SiO2

Influence of SER process on Carbon Balance

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0%

20%

40%

60%

80%

100%

Oxy-SER steam gasification

Ga

sif

ier

Ca

rbo

n D

istr

ibu

tio

n

C in Syngas

C in tars

C in Char

C in Carbonate

Results of the Oxy-SER experiments

• High H2-concentrations in Syngas

• No significant difference in the syngas between the two regeneration

modes

• Higher H2O and CO2 concentration in the fluegas due to the gas

recirculation and lack of air-nitrogen

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0%

20%

40%

60%

80%

100%

SER Oxy-SER

Syn

ga

s c

om

po

sitio

n in v

ol-%

dry

H2 CO CH4 C2-C4 CO2

0%

20%

40%

60%

80%

100%

SER Oxy-SER

Flu

ega

s c

om

po

sitio

n in v

ol-

%

H2O CO2 O2 N2

Gasifier 660 °C Regenerator 920 °C

SER Characteristics and Modeling

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• Good agreement between model/simulation and experimental data

• C/H stoichiometry can be adjusted for synthesis or to compensate downstream

fluctuations (e.g. by Gasifier temperature)

0

0.5

1

1.5

2

0

10

20

30

40

50

60

70

80

600 650 700 750

Gas

Yie

ld in

m³t

r./k

g fu

el,d

af

Gas

Co

mp

osi

tio

n in

Vo

l.-%

Gasifier Temperature in °C

YGas H2 CO2 H2 CO Yield

Gas Composition

0.3

0.4

0.5

0.6

0.7

0

2

4

6

8

10

12

600 650 700 750

H2-y

ield

m³t

r./k

gfu

el,

da

f

mo

lar

rati

o

Vergaser-Temperatur in °C

H2/CO CO/CO2 Y[H2]

SER Characteristics and Modeling

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• Process model shows high cold gas efficiencies of >65%

• Break in efficiency trend at 680°C is caused by additional fuel in Regenerator

• Higher efficiencies can be achieved by optimised heat recovery and gas

preheating

0

0.5

1

1.5

2

0

10

20

30

40

50

60

70

80

600 650 700 750

Gas

Yie

ld in

m³t

r./k

g fu

el,d

af

Gas

Co

mp

osi

tio

n in

Vo

l.-%

Gasifier Temperature in °C

H2 CO CO2 CH4 C2H4 Yield

Gas Composition

0

0.6

1.2

1.8

2.4

0

20

40

60

80

100

600 650 700 750

Gas

Yie

ld in

m³t

r./k

g fu

el,d

af

Co

ld G

as E

ffic

ien

cy η

in %

Gasifier Temperature in °C

ηCGE ηCGE,ges YGas YGas,ges

𝜂𝐶𝐺𝐸,𝑔𝑒𝑠 =𝑚 𝑆𝑦𝑛𝑔𝑎𝑠 𝐻𝑢,𝑆𝑦𝑛𝑔𝑎𝑠

(𝑚 𝐵𝑆,𝑉𝑒𝑟𝑔𝑎𝑠𝑒𝑟 +𝑚 𝐵𝑆,𝑅𝑒𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑜𝑟) 𝐻𝑢,𝐵𝑆

𝑌𝐺𝑎𝑠,𝑔𝑒𝑠 =𝑌𝐺𝑎𝑠

(𝑚 𝐵𝑆,𝑉𝑒𝑟𝑔𝑎𝑠𝑒𝑟 +𝑚 𝐵𝑆,𝑅𝑒𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑜𝑟)

Gasification efficiency

Summary SER gasification

• (Oxy-)SER operation process was successfully demonstrated in pilot scale

• High H2 concentrations of ~70 vol.-%dry were achieved

• low tar concentrations due to CaO bed material

• high gas yields

promising production of syngas with a suitable stoichiometry for

methanation or liquefaction processes

• High CO2 concentrations of >90 vol-%dry in the Regenerator were achieved

when using oxy-fuel combustion in the Regenerator

promising technology for the creation of a hydrogen-rich syngas with a

pre-combustion CCS

• High cold gas efficiencies of >65% can be achieved

• higher efficiencies are possible when

• improving the heat integrating of the system

• using steam/ORC cycles to utilise the heat streams

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Summary SER gasification

• Co-Gasification of biomass and fossil fuels possible:

Use of (dried) lignite as fuel is possible if sufficient biomass is not

available

Use of seasonal biomass possible

• Due to the integration of a steam/ORC cycle, flexible co-production of el.

energy and syngas possible

• The SER gasification process is a promising and efficient process for

the production of storable energy out of solid fuels

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more results can be found in:

• Daniel Schweitzer: Pilot-Scale Demonstration of Oxy-SER steam Gasification: Production of syngas with Pre-Combustion CO2 capture; Energy Procedia 02 (2016)

• Max Schmid: Gasification of biomass with the Oxy-SER process for syngas production with in situ CO2capture in a 200 kWth pilot plant

In: The 6th High Temperature Solid Looping Cycles Network Meeting; Milan; 02.09.2015

Thank you for your attention

The work was carried out within the “Synthetic liquid hydrocarbons – Energy storage with highest

energy density” project.

The authors gratefully acknowledge the financial support from the Helmholtz Alliance e.V. under

their “Impuls- und Vernetzungsfonds” initiative.

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Contact:

Daniel Schweitzer

Institute of Combustion and Power Plant Technology

University of Stuttgart

daniel.schweitzer@ifk.uni-stuttgart.de

http://www.ifk.uni-stuttgart.de