Prof. Dr. techn. G. Scheffknecht

Institute of Combustion and Power Plant Technology

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

Flue

Gas

The Calcium Looping (CaL) Process

Air

Coal

ASU

O2

N2

CO2-lean Flue Gas

CO2-rich

Flue Gas

CO2 to Storage

CaO (+CO2)

CaORegenerator

T = 900 CCaCO3 + Heat CO2 + CaO

CoalAir

CO2

Conditioning

Make-up Limestone

Purge

CarbonatorT = 650 C

CO2 + CaO CaCO3 + Heat

Coal-fired

Powerplant

G 1

SteamGenerator

CaL Steam Generator

G 2

3

The Calcium Looping (CaL) Process

CO2 Capture Costs1: Over 90% CO2 Capture efficiency

demonstrated

CO2 Avoidance Cost ~ 20 €/t CO2

Cost of Electricity ~ 40 €/MWh

Purged material can be efficiently utilized in cement or FGD processes

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., 20072 Hawthorne et al., Energy Procedia, 2009 4

Flue

Gas

Air

Coal

ASU

O2

N2

CO2-lean Flue Gas

CO2-rich

Flue Gas

CO2 to Storage

CaO (+CO2)

CaORegenerator

T = 900°CCaCO3 + Heat CO2 + CaO

CoalAir

CO2

Conditioning

Make-up Limestone

Purge

CarbonatorT = 650°C

CO2 + CaO CaCO3 + Heat

Coal-fired

Powerplant

G 1

SteamGenerator

CaL Steam Generator

G 2

Process CharacterisationElectr. heated10 kWth facility

Charitos et al., Abanadeset al.

TGA SorbentCharacterisationGrasa et al.

R&D Calcium Looping Process Roadmap

5Process Idea

CommericalPlant

Labscale

ProcessSimulation

10 kWth –DFB Facility

200 kWth -Pilot PlantProcessDemonstration

Demo PlantShimizu

et al. 1999

Process Demonstration: Realistic ProcessConditions• No external heating• Real Flue Gas• Oxyfuel Calcination• Coal influence (S, ash)

Process Simulation & Cost Calculations

Hawthorne et al., Poboss et al., Abanades et al.

CarbonatorRegenerator

CO2-lean Flue Gas

CO2-richGas

L-valve

FBHX

TertiaryO2/CO2

SecondaryO2/CO2

Loop seal

Flue Gas

Fuel + O2/CO2

CaCO3

CaO

200 kWth DFB Calcium Looping Plant

BottomLoop seal

Carbonator:

Turbulent CFB Reactor

Good gas-solid contact

Lower entrainment than fast fluidized CFB

Looping Rate controlled by L-valve

Bottom loop seal regulates bed inventory

Temperature controlled by Looping Rate and Fluidized Bed Heat Exchanger

Regenerator:

Fast fluidized CFB calciner

Temperature controlled by oxy-combustion

6

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

Overview of Pilot Plant Operation

7

500

600

700

800

900

1000

Tem

pera

ture

[°C]

T Regenerator

T Carbonator

0

5

10

15

20

08:05 08:51 09:37 10:23 11:09 11:55 12:41 13:27 14:13CO2

Conc

. [vo

l-%

] YCO2, in

YCO2,out

60

70

80

90

100

CO2

Cap

ture

[%]

ECO2

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

Overview of Pilot Plant Operation

8

500

600

700

800

900

1000

Tem

pera

ture

[°C]

T Regenerator

T Carbonator

0

5

10

15

20

08:05 08:51 09:37 10:23 11:09 11:55 12:41 13:27 14:13CO2

Conc

. [vo

l-%

] YCO2, in

YCO2,out

60

70

80

90

100

CO2

Cap

ture

[%]

ECO2

0

5

10

15

20

18:44 18:48 18:52 18:57 19:01 19:05

CO2

Conc

. [vo

l-%]

yCO2,in

yCO2,out

70

75

80

85

90

95

100

CO2

Capt

ure

[%]

ECO2

ECO2,eq

600

650

700

Tem

pera

ture

[°C]

Tcarbonator

Pilot plant operates as designed:

Facility responds quickly to set

point changes, e.g. inlet CO2

vol.-% concentration

Capture efficiencies are

constant over time once system

stabilized

CO2 capture close to equilibrium

System Response: Change in Inlet CO2 Conc.

2. Temp increase from carbonation

1. CO2 Conc. increase

3. Capture increases due to higher CO2partial pressure

4. Capture decreases because of temperature increase

9

Results Summary: Effect of Temperature

50

60

70

80

90

100

620 630 640 650 660 670 680 690 700 710

CO2

Capt

ure

Effic

ienc

y [%

]

Carbonator Temperature [°C]

CO2 inlet concentration 10%

CO2 inlet concentration 15%

Equilibrium

10% 15%

Every data point is a steady state where

Solid samples taken & analyzed

Circulation rate measured

CO2 capture measured

All capture efficiencies are close to maximum equilibrium value

Highest CO2 capture achieved between 635-660°C for inlet concentrations of 10-15 Vol.-% CO2

Over 90% capture efficiency in steady state pilot operation

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.

10

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

Conclusions and Outlook

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