progress in ca-based co 2 capture research at cranfield university ondřej mašek, adina bosoaga,...
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Progress in Ca-based Progress in Ca-based COCO22 capture research capture research at Cranfield at Cranfield UniversityUniversity Ondřej MašekOndřej Mašek, Adina Bosoaga, , Adina Bosoaga,
John OakeyJohn Oakey
Outline of our activities
1) flash calcination of limestone
2) entrained flow carbonation
3) entrained flow CO2 capture in a pilot-scale combustion facility
4) effects of operating pressure and contaminants on performance
of Ca-based sorbents
5) Calcium looping
1) Flash calcination
- effects of temperature on flash calcination
- effects of sorbent particle size
- effects of CO2 partial pressure
OBJECTIVES:
Flash calcinationCH4
N2
CaCO3
Nozzle Solids, gas
mixture
Calcination zone,~ 0.5 m length
Cooling zone
Cyclone
O2/ArO2/Ar +CO2
- limestone with 95.5 % CaCO3
- feeding rate 10 g min-1
- temperature: 750 – 1000 °C
- <100, 300-350 and 500-600 m
- CaO/CO2 : 0.06 – 0.37
solids collection
Operating parameters
Flash calcination
- at 850 °C larger particles do not decompose
- flash calcination efficiency reached over 90 % for fine particles
Effects of temperature and particle size on calcination efficiency
Flash calcination
- decreasing CO2 partial pressure lowers the calcination temperature
- with increasing temperature, the effect of CO2 partial pressure decreases
CO2 partial pressure
Effect of CO2 partial pressure on calcination efficiency of <100 m fraction
0
10
20
30
40
50
750 800 850 900 950 1000 1050
Temperature [C]
Cal
cin
atio
n e
ffic
ien
cy [
%]
0.3
0.06
Effect of CO2 partial pressure on calcination efficiency of 500-600 m fraction
CO2 partial pressure
Flash calcination
- decreasing CO2 partial pressure lowers the calcination temperature
- with increasing temperature, the effect of CO2 partial pressure decreases
Flash calcination
a b
fresh limestone <100 m calcined limestone <100 m
- Insignificant sintering under the conditions employed
2) Entrained flow carbonation
- effects of temperature on entrained flow carbonation
- effects of particle residence time on conversion
- effects of CaO/CO2 ratio
OBJECTIVES:
Entrained flow carbonation
reaction zone
particle feeding system
air inlet
rotameter
needle
CO2 inlet
to CO2 analyser
fluidised bath
rotameter
filters
vent
cooling coil
filter
Operating parameters
- starting material: natural limestone (99.95 % CaCO3)
- calcination in an oven (30 min. at 850 °C)
- mean particle diameter: 60 m
- particle residence time :1-3 s
- temperature: 550 – 670 °C
- CaO/CO2 ratio: 0.85-2.15
Entrained flow carbonation
Entrained flow carbonation
CaCO3
CaO
CaCO3
CaO
SEM image of the solids carbonated at 587 ° C with residence time of 2.59 s.
3) CO2 capture in pilot scale combustion facility
- lime performance in a real combustion atmosphere
- effects of temperature on carbonation
OBJECTIVES:
Nat. gas preheater
CO2 capture in pilot scale combustion facility
The FBCThe FBC
Screw feeder
Optional PC burner
Material testing zone
Heat exchanger
Cyclone
Lime injection
FBC
Particle removal system
Total combined thermal output of 150 kW
The CarbonatorThe Carbonator
Ca
rbo
na
tor
Temperature Coal feed rate CaO feed rate CO2 in CO2 out CaO/CO2
[°C] [kg/h] [kg/h] [vol. %] [vol. %] [-]550 3.2 3.6 12.1 10.03 0.2625 3.2 3.6 12.53 11.01 0.2730 3.2 3.6 12.28 11.67 0.2750 3.2 3.6 12.6 11.7 0.2
- commercial lime with 96% CaO (< 75 m)
- feeding at 3.6 kg/h (limited by the feeding system)
- residence time within the carbonator was about 2 s
CO2 capture in pilot scale combustion facility
Operating parameters
Temperature CO2 reduction Particle conversion Min. possible CO2 conc. CO2 captured / max. CO2 capture
[°C] [%] [%] [vol. %] [vol. %]
550 17.1 99.5 9.68 85.5
625 11.7 66 10.02 58.6
730 4.9 19.2 9.82 24.6
750 7.1 29.7 10.08 35.7
0
5
10
15
550 625 730 750
carbonation temperature [°C]
CO
2 c
onc.
[vol
.%]
without capture with capture max. capture
0.00
0.10
0.200.30
0.40
0.50
0.60
0.700.80
0.90
1.00
550 625 730 750
carbonation temperature [°C]
CO
2 c
aptu
red
/ max
. CO 2
cap
ture
CO2 capture in pilot scale combustion facility
Results
4) Effects of op. pressure and contaminants on performance of Ca-based sorbents
- effects of operating pressure
- effects of steam
- effects of SO2 partial pressure
- effects of CO2 partial pressure
OBJECTIVES:
el. furnace
sample feedflue gas
pressure vessel
- operating pressure: 0.1 – 1.5 MPa.
- operating temperature: 950 °C
- SO2 partial pressure: 250 – 5000 ppmv
gas inlet
Operating parameters
Effects of op. pressure and contaminants on performance of Ca-based sorbents
- transport of solids between carbonator and calciner
- effects of steam
- effects of SO2 partial pressure
- effects of CO2 partial pressure
- cycle optimisation
OBJECTIVES:
5) Calcium looping
Flue gas
gas burner
CO2 rich flue gas
solids extraction
cyclone
loop seal
loop seal
CA
RB
ON
AT
OR
650
°C
CA
LC
INE
R95
0 °
C
flue gas
Calcium looping
CALCINER
- bubbling fluidised bed
- temperature 950 °C
- CH4/O2 burner
CARBONATOR
- entrained flow reactor
- temperature 650 °C
- CH4/air burner
