Institute of Combustion and Power Plant Technology
Prof. Dr. techn. G. Scheffknecht
Demonstration of the Calcium Looping Process:
High Temperature CO2 Capture with CaO in a
200 kWth Dual Fluidized Bed Pilot Facility
Presented by: Heiko Dieter
Authors: Heiko Dieter, Craig Hawthorne
Trondheim TCCS-6 Conference, June 14-16th, 2011
Contents

The Calcium Looping CO2 Capture Process

The 200 kWth Calcium Looping Pilot Plant

Pilot Plant Results

Conclusions and Outlook
2
The Calcium Looping (CaL) Process
CO2 to Storage
CO2-lean Flue Gas
G2
G1
CaL Steam
Generator
Steam
Generator
Coal-fired
Powerplant
Air
CO2
Conditioning
Coal
Flue
Gas
Carbonator
CaO
CO2-rich
Flue Gas
Regenerator
T = 650 C
T = 900 C
CO2 + CaO  CaCO3 + Heat
CaCO3 + Heat  CO2 + CaO
CaO (+CO2)
Purge
O2
Air
Make-up
Limestone
Coal
ASU
N2
3
The Calcium Looping (CaL) Process
G2
G1
Coal-fired
Powerplant
Air
CO2
Conditioning
CaL Steam
Generator
Steam
Generator
Coal
Flue
Gas
Carbonator
CaO
Regenerator
T = 900°C
CaO (+CO2)
Purge
CaCO3 + Heat  CO2 + CaO
O2
Air
 CO2 Avoidance Cost ~ 20 €/t CO2
CO2-rich
Flue Gas
T = 650°C
CO2 + CaO  CaCO3 + Heat
CO2 Capture Costs1:
 Over 90% CO2 Capture efficiency
demonstrated
CO2 to Storage
CO2-lean Flue Gas
 Cost of Electricity ~ 40 €/MWh
Make-up
Limestone
 Purged material can be efficiently
utilized in cement or FGD
processes
Coal
ASU
N2
Electricity Generation2:
 Plant electric efficiency including
CO2 capture and compression
calculated at 39.2%
 6.4% penalty
 Power output increases ~ 45%
1 Poboss
et al., Cooretec Final Report 2008; Abanades et al., Environ. Sci. Technol., 2007
2 Hawthorne et al., Energy Procedia, 2009
4
R&D Calcium Looping Process Roadmap
Process Simulation & Cost Calculations
Hawthorne et al., Poboss et al., Abanades et al.
TGA Sorbent
Characterisation
Grasa et al.
Process Characterisation
Electr. heated
10 kWth facility
Process Demonstration:
Realistic Process
Conditions
• No external heating
• Real Flue Gas
• Oxyfuel Calcination
• Coal influence (S, ash)
Charitos et al.,
Abanades
et al.
Shimizu
et al.
1999
Process Idea
Labscale
10 kWth –
DFB
Process
Simulation Facility
Commerical
Plant
Demo
200 kWth Plant
Pilot Plant
Process
Demonstration
5
200 kWth DFB Calcium Looping Plant
Regenerator
Carbonator
CO2-rich
Gas
 Turbulent CFB Reactor
CO2-lean
Flue Gas
L-valve
Loop seal
CaO
Fuel + O2/CO2
CaCO3
 Lower entrainment than fast fluidized CFB
 Bottom loop seal regulates bed inventory
Flue Gas
Tertiary
O2/CO2
 Good gas-solid contact
 Looping Rate controlled by L-valve
FBHX
Secondary
O2/CO2
Carbonator:
Bottom
Loop seal
 Temperature controlled by Looping Rate
and Fluidized Bed Heat Exchanger
Regenerator:
 Fast fluidized CFB calciner
 Temperature controlled by oxycombustion
6
Overview of Pilot Plant Operation
 3 measurement campaigns completed with over 300 h of successful operation
 Dual Fluidized Bed system proved flexible and robust
 Operated over a wide range of temperatures and looping rates
 L-valve & loop seal system delivers stable sorbent looping rate
CO2 Conc. [vol-% ]
CO2 Capture [%]
Temperature [°C]
1000
900
800
T Regenerator
700
600
500
100
90
80
T Carbonator
ECO2
70
60
20
15
YCO2, in
10
5
YCO2,out
0
08:05
08:51
09:37
10:23
11:09
11:55
12:41
13:27
14:13
7
Overview of Pilot Plant Operation
 Over 90% capture efficiency achieved over a wide range of operating conditions
 Oxyfuel Regenerator performed well as a combustor:
 High fuel burnout (low CO), good controlability and uniform temperature profiles
 Complete calcination of incoming carbonated sorbent and make-up CaCO3
CO2 Conc. [vol-% ]
CO2 Capture [%]
Temperature [°C]
1000
900
800
T Regenerator
700
600
500
100
90
80
T Carbonator
ECO2
70
60
20
15
YCO2, in
10
5
YCO2,out
0
08:05
08:51
09:37
10:23
11:09
11:55
12:41
13:27
14:13
8
System Response: Change in Inlet CO2 Conc.
Temperature [°C]
700
Pilot plant operates as designed:
Tcarbonator
2. Temp increase
from carbonation
650
CO2 Capture [%]
600
100
95
90
3. Capture increases
due to higher CO2
partial pressure
ECO2,eq
85
80
75
ECO2
CO2 Conc. [vol-%]
10
5
Facility responds quickly to set
point changes, e.g. inlet CO2
vol.-% concentration

Capture efficiencies are
constant over time once system
4. Capture decreases
because of temperature
increase
70
20
15

stabilized
1. CO2 Conc. increase
yCO2,in

yCO2,out
CO2 capture close to equilibrium
0
18:44
18:48
18:52
18:57
19:01
19:05
9
Results Summary: Effect of Temperature
Every data point is a steady state where
100
Equilibrium
10%
CO2 Capture Efficiency [%]
90
15%
80

Solid samples taken & analyzed

Circulation rate measured

CO2 capture measured
All capture efficiencies are close to
70
maximum equilibrium value
CO2 inlet concentration 10%
60
CO2 inlet concentration 15%
Highest CO2 capture achieved between
635-660°C for inlet concentrations of
50
620
630
640
650
660
670
680
690
700
710
10-15 Vol.-% CO2
Carbonator Temperature [°C]

Ref: Hawthorne and Dieter, High Temperature CO2 Capture with CaO in a
200 kWth Dual Fluidized Bed Pilot Facility. 2nd Efficient Carbon Capture for
Coal Power Plants, June 2011.
Over 90% capture efficiency in
steady state pilot operation
10
Conclusions and Outlook
Calcium Looping process successfully demonstrated on a 200 kWth pilot facility:
 CO2 capture efficiency over 90 % achieved
 Plant showed robust performance and flexibility over 300 h of operation
 Full sorbent calcination in oxy-fired regenerator achieved
 Low sorbent loss due to attrition, i.e. ~ 5 wt.% bed/h
Recently obtained results and upcoming R&D topics:
 Influence of Make-up and steam content in flue gas on CO2 capture efficiency
 Tests completed and will be published in the near future
 Influence of sulfur and coal ash on sorbent activity and pilot operation
11
Acknowledgements
The results from the 200 kWth Calcium Looping pilot plant were produced as part of a joint
university-industrial research & development project funded by EnBW Kraftwerke AG.
12