13th China-Japan Symposium on Coal and C1 Chemistry
August 31～ Sept. 4, 2015, DunHuang, China
Development of Three-Tower Technology
for Chemical Looping Coal Combustion
Shiying Lin, Tomonao Saito
Keiichiro Hashimoto
Japan Coal Energy Center (JCOAL)
1
Background-1
Concept of Chemical Looping coal Combustion
(CLC)
To protect the environment changing, coal combustion must reduce its CO2 emission by capture and
storage. Chemical looping is a potentially high technology for coal combustion with CO2 capture
efficiently.
A chemical-looping coal combustion system, which is schematically presented in Fig, using
circulating fluidized bed witch consist two main reactors, a fuel reactor and an air reactor. An oxygen
carrier, typically a metal oxide, is employed to transfer oxygen from the air reactor to the fuel reactor,
and circulates between these two reactors.
ＭＯX-1 (Reduction state)
Iron oxide
Oxygen carrier
CO2
Fe2O3 + 1/6C(Coal)
→ 2/3Fe3O4+1/6CO2
Chemical Oxidation
Looping （Air reactor）
N2+Heat
2/3Fe3O4 + 1/6O2(Air)
→ Fe2O3 +Q
Reduction
（Fuel reactor）
Coal
（reducing agent）
ＭＯX (Oxidation state)
Air
（Oxidizing agent）
Concept of chemical looping coal combustion
2
Road Map of Coal CLC Technology Development in JAPAN
Under these situation, Japan decided to develop the CLC Coal utilization Technology into
commercialization
Phase I: A 6 years plan including 1 MW bench scale facility testing
（NEDO project）will be started in 2015.
Ye ars
CCS- EU
CCS- USA
CCS- JPN
2015
2016
2017
2018
2019
2 0 2 1 ～2 0 2 5
2020
2 0 2 6 ～2 0 3 0
CCS
FG-2
Tomakomai
ADM
Ohsaki
Stage gate
CLC
Ac tion
Plan
◇Carrier development
・Reaction perfomance
・Durability
・Fluidity (hot and cold)
Pilot (10MWth（30t/d）)
◇PDU （1MWth(2t/d)）study
Durability, Reactivity
Fluidity
Demonstration （40～70MWe)
Cost performance
Commercial
3
4
Target of CO2 capture cost for the CLC development
Other variable
cost
Coal
Target
CO2 capture
90%
Now
Depreciation
CO2 capture
cost
Now
Without CCS
Career
Other Fixed
cost
CO2 capture cost, Japanese Yen/ton-CO2
Power generating cost, Japanese Yen/kWh
A study of market shown that the cost of CO2 capture for the current technology is
similar to that of other CO2 capture techniques, and that the 2,500 yen/t-CO2 (included
CO2 compression and liquefaction) is a target for CLC development to achieve
commercial viability in around 2030.
4
Target of Oxygen Carrier Consumption Cost for the CLC Development
Oxygen carrier consumption cost shell be below 400 Japanese Yen/(MWeh) with
the scale of power generation is larger than 500MWe
Carrier cost [ Japanese Yen/kg ]
800
Target of Carrier
Development Area
Carrier Consumption Cost <
400 Japanese Yen/(MWehr)
700
600
500
400
500 MWe plant
300
（inventory 1000t）
200
（inventory 2000t）
（inventory 2900t）
100
0.4
0.8
1.2
1.6
2
2.4
Consumption ratio [ wt%/d ]
2.8
5
Three-Tower (reactors) CFB CLC system
A process that consists primarily of an air reactor (AR), coal reactor (CR), and
volatiles reactor (VR) was selected, and an conceptual design was produced for
the reactor configuration and technical parameters
Steam
(Power generation)
Heat Recovery
Cyclone
CR: Coal Reactor
AR
VR: Volatile Reactor
Coal
VR
CR
Water
Ash
Stem
Fuel reactor
Air Combustor
AR: Air Reactor
Stem
dust
precipitator Stack
Air
Stem
Compressor
Water
Ash
6
Concept of coal in CR, and char reaction with Fe2O3
In CR, coal is first decomposed into volatile and char. Volatile is
then sent in VR, and char in CR will react will steam further to
produce H2 and CO. Since H2 and CO will be reacted with Fe2O3
immediately, char-steam reaction
C + 2H2O → 2H2 + CO2
T: 1023 K; P: 3.0 MPa (N 2 0.5 l/min, steam 1 l/min]
Carbon conversion, X [-]
1
PH2 /PH2O =0
P
/PH2O =0.2
HH2
2 /Steam=0.2
PH2 /PH2O =1.0
PH2 /PH2O =0
PH2 /PH2O =0.2
PH2 /PH2O =1.0
Ca loaded coal
Char
0.8
0.6
0.4
CO2
Char
C
0.2
0
2H2 + 2Fe2O3 → 4FeO + 2H2O
0
10
20
30
40
Time [min]
50
60
H2 effect on char steam gasificaiton
2H2O
Q
2H2
2Fe2O3
4FeO
7
Concept of char reaction with Fe2O3
Concept of NH3 decomposition in VR
NH3 decomposition conversion (1-X) [-]
Fuel-N of coal may first form reductive nitrogen compounds as
NH3 in CR, and then be introduced into VR. In VR, NH3 will
decompose into N2 and H2, and the NH3 decomposition will be
improved by Fe2O3.
1
H2:NH3 = 1:1
H2:NH3 = 0.5:1
H2:NH3 = 0.2:1
H2/NH3 = 0.0:1
0.8
0.6
Improve
NH3 → N2 + H2
0.4
H2 + Fe2O3
→ 2FeO + H2O
0.2
0
50
100
150
200
Temperature [℃]
250
H2 effect on NH3 decomposition
(equilibrium calculation )
300
Concept of NH3 decomposition
8
improved by Fe2O3
Background-2
CLC Process Analysis
A basic model of the CLC process was produced using the AspenPlus software and used
to analyze the process under the conditions of a 250MWth plant. It found that the volume of
circulating CLC carrier is roughly the same as the circulation of CFBC, and that inner
desulfurization and very low NOX combustion are possible.
FR exhaust (107℃)
Analysis Conditions:
Boiler Size: 250MWth
Coal Supply: 36,655 kg/h
Inner De-Sulfur
Recycle gas
12600 kg/h
(H2O 61.5%,
CO2 37.8%)
(150℃)
46016 kg/h
(H2O 61.5%, CO2 37.8%)
634.7kmol/h(dry)
(CO2 98.1 dry% )
(SO2, 0.0577 kmol/h(27)
91 ppm (dry)
NOX, 0.00014kmol/h
0.22ppm(dry)
QVRexhust 8
QARexhust 31
Exhaust gas
composition
(Dry)
CO2
(%)
From VR
98.09
From AR
13
N2
(%)
CO
(ppm)
H2
(ppm)
SO2
(ppm)
NOX
(ppm)
1.88
43
44
90
0.22
86.2
0.09
0.01
2.1
25.4
ash
482 kg/h
ILMENITE 620 kg/h
CaSO4 29 kg/h (0.21 kmol/h(64)
CaO 0.9kg/h
VR
980℃
career circulation
1,780,000 kg/h
QvR 0.3
AR exhaust (60℃)
279151 kg/h
(N2 85%, O2 0.19%
CO213.5%, H2O 1.7%)
8255kmol/h(dry)
(N2 86dry%, CO213.8dry%
(SO2, 0.019 kmol/h(5)
2 ppm(dry)
NOX, 0.23 kmol/h
25 ppm(dry)
ratio against coal supply
50
CaO circulation
2753 kg/h (49 kmol/h)
CR
900℃
Coal 35,655kg/h(Q100)
(S, 0.33kmol/h(100))
limestone 23 kg/h
ILMENITE 620 kg/h
Air 290,000kg/h
QCR 2.3
AR
950℃
QAR 48
9
Organization chart of the project plan
NEDO
Environment
Department
Mitsubishi HitachiPower
Systems, Ltd.(MHPS)
(former Babcock-Hitachi,
Ltd.)
CLC plant design
Japan Coal
Energy Center(JCOAL)
Developments of oxygen
carriers, Process analysis
The Institute of
Applied Energy(IAE)
Estimate for CLC plant
market and
cost performance
National Institute of Advanced
Industrial Science and Technology
Osaka University
Simulation of the Fluidization
Chuo University
Mixture of Coal with
Carrier in Fluidized bed
Kanagawa Institute of
Technology (KAIT)
mechanism of the reaction
between coal and carriers
Advanced Industrial Science
And Technology (AIST)
Reactivity and abrasion
resistance of carriers
The University of TOKYO
production method for
high activity carriers
10
Summary
(1) Chemical looping coal combustion technology development haven been scheduled
in Japan. A first 6 years project (Phase I) will started in October this year.
(2) A three towers (reactors) CFB will be developed for the CLC process.
(3) The CLC market is coal-fired power plants for small and medium-sized electric
utilities.
(4) CO2 capture cost of 2,500 Japanese yen/t-CO2 or less (including CO2 compression
and liquefaction) in the 2030.
(5) Target of oxygen carrier consumption cost is below 400 Japanese yen/MWh.
11
Thank you for your attention
12