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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
2
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
5
• 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
6
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
7
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
8
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
9
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
11
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
12
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
13
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
14
• 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
15
• 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
16
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
17
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.
18
Contact:
Daniel Schweitzer
Institute of Combustion and Power Plant Technology
University of Stuttgart
http://www.ifk.uni-stuttgart.de