Chemical Looping Combustion withliquid fuels in a 1 kWth unit using a
Fe- based oxygen carrier
6th High Temperature Solid Looping Cycles Network Meeting1 – 2 September 2015
A. Serrano, F. García-Labiano L. F. de Diego, Pilar Gayán Alberto Abad,
Juan AdánezInstituto de Carboquímica, CSIC-ICBCombustion and Gasification group
1. Introduction
2. Experimental
3. Results
4. Conclusions
1. Introduction
3
Introduction
Ed Dlugokencky and Pieter Tans, NOAA/ESRL (www.esrl.noaa.gov/gmd/ccgg/trends/)
Recent global monthly mean CO2, Mauna Loa Observatory
4
Our society is at a turningmoment to develop an effectivestrategy to adress climate change
400 ppm CO2
IPCC warned that it is imperative to take urgentand effective actions to reduce global emissions
Introduction
5
CCS technologies play an important role as they are capable of achieve 14% of the reductions needeed to keep the rise in global temperature below 2 ºC [1].
2%
Powergeneration
Efficiency and fuel switching
7%
Nuclear End use fuel switching
9%
CCS
30%
Renewables End use energyefficiency
38%
14%cumulative CO2
emission reductions
[1] Global CCS Institute 2014, The Global Status of CCS: 2014,Melbourne, Australia.
Introduction
6
CLC is based on the transfer of oxygen from air to fuel by means of an OC which is continuouslyreduced and oxidized. Doing so, direct contact between air and fuel is avoided and a pure streamof CO2 is produced.
Fuel
Condenser
H2O
Cyclone
CO2
Unreacted N2 + O2
Air
FUEL REACTOR
AIRREACTOR
Me
MeO
Introduction
7
Renewable fuels Fossil fuels
[2] RFA, Renewable Fuels Association: 2015 Ethanol Industry Outlook http://www.ethanolrfa.org/[3] van Straelen, J., Geuzebroek, F., Goodchild, N., Protopapas, G., Mahony, L. CO2 capture for refineries, a practical approach (2010) International Journal of Greenhouse Gas Control, 4 (2), pp. 316-320
They have the advantage of achieving negativeCO2 emissions
EtOH
Its production and use have increased dramaticallysince early 2000. In 2014, ≈93.7 billion litres ofethanol were produced and this trend is expectedto continue [2]
In the transition to a low-carbon ecnonomy, theimplementation of CLC technology with liquid fuelsfrom refineries could reduce 1 billion metric tonsCO2/year [3]
Diesel – Engine oil
They were selected as representatives fuels obtained inrefieneries, but the ultimate goal in future works willinvolve the use of heavy residual oils
Liquid fuels
8
AIM
This work intended to analyze the employability of
ethanol, diesel and engine oil as fuels in a
continuous CLC unit with a Fe- based OC
2. Experimental
9
Experimental
10
AIM
Given the relevance of theimpurities in the performance of CLC, these compounds weredetermined
Elementaryanalysis
Distillationcurves
FUELS
Three different behaviours wereobserved according to theirdifferent molecular structure
* Ash content <0,01 %m/m
Temperature (ºC)
0 100 200 300 400 500
Dis
tilled
fra
cti
on
(vo
l.%
)
0
20
40
60
80
100
EtOH
Diesel
Engine oil
Experimental
11
AIM
OC developed by ICB-CSIC [4]
Prepared by incipient wetness impregnation
To ensure that OC mantained its propertiesafter operation, the fresh OC was characterized
Fe20-γAl2O3
OXYGEN CARRIER
[4] Gayán, P., Pans, M.A., Ortiz, M., Abad, A., De Diego, L.F., García-Labiano, F., Adánez, J. Testing of a highly reactive impregnated Fe 2O 3/Al 2O 3 oxygen carrier for a SR-CLC system in a continuous CLC unit (2012) Fuel Processing Technology, 96, pp. 37-47.
Experimental
12
1 kWth CLC FACILITY
1.- Fuel reactor
2.- Loop seal
3.- Air reactor
4.- Riser
5.- Cyclone
6.- Solids valve
7.- Solids valve
8.- Filters
9.- Pumps
10.- Evaporator
Components2 interconnected fluidized bedreactors, a riser, a cyclone, avalve to manage solid circulationflow and a loop seal to preventgas mixing between reactors
DimensionsFR 0,026-0,085 m. i. d.AR 0,052 m. i. d.
Fuel supplyIt was controlled by peristalticpumps.The fuel flow was completelyevaporated in a furnace beforeit reached the FR.
Gas Chromatograph quantifiedHCs.
Fuel
Experimental
13
DATA ANALYSIS
Oxygen carrier reductionEthanol
C2H5OH + 6 Fe2O3 + 12 Al2O3↔ 12 FeAl2O4 + 2 CO2 + 3 H2O
Diesel
C15H29 + 44,5 Fe2O3 + 89 Al2O3↔ 89 FeAl2O4 + 15 CO2 + 14,5 H2O
Engine oil
C18H34 + 53 Fe2O3 + 106 Al2O3↔ 106 FeAl2O4 + 18 CO2 + 17 H2O
Oxygen carrier oxidation
4FeAl2O4 + O2 2Fe2O3 + 4 Al2O3
𝜼𝒄 =2xCO2
+xCO+z∙xCxHyOz out ∙Fout− z∙(xCxHyOz)in∙Fin
b∙(xCxHyOz)in∙Fin
Ф =FFe2O3b∙Ffuel
Combustion efficiency
Oxygen carrier to fuel ratio
CO2 capture efficiency
𝜼𝒄𝒄 =xCO2
+xCO+X∙xCxHyOz out ∙Fout
(xCxHyOz)in∙Fin
3. Results
14
Results
15
ETHANOL
• In the range 800-900ºC, an increase in T produced an increase in ηc as OC reactivity isimproved with T
• Regarding gas product distribution, light hydrocarbons were never measured.
• CO2 was the major compound together with a mixture of CO+H2+CH4 to a lesser extent
1 2 3 4 5
Co
nc
en
tra
tio
n (
vo
l. %
, d
ry b
as
is)
0
20
40
60
80
100
CO2
CO
H2
CH4
Temperature 900ºC
1 2 3 4 5
Co
mb
usti
on
eff
icie
nc
y,
c (
%)
50
60
70
80
90
100
EtOH 800ºC
EtOH 900ºC
Results
16
DIESEL
• Regarding gas product distribution, againmixture CO+H2+CH4 were the only compoundsdecreasing ηc .
• As in the previous case, CH4 was measuredwhich suggests that CH4 could be anintermediate on HCs conversion to CO2.
• In the range 800-900ºC, temperature had a slight effect on ηc
1 2 3 4 5
Co
nc
en
tra
tio
n (
vo
l. %
, d
ry b
as
is)
0
20
40
60
80
100
CO2
CO
H2
CH4
Temperature 900ºC
0 1 2 3 4 5
Co
mb
us
tio
n e
ffic
ien
cy,
c (
%)
50
60
70
80
90
100
Diesel 800ºC
Diesel 900ºC
Results
17
ENGINE OIL
• Only the mixture CO+H2+CH4 decreaed ηc and CH4 remained constant suggesting again that itcould be a stable intermediate.
• In the range 800-900ºC, temperature played animportant role for Ф<1,8
1 2 3 4 5
Co
nc
en
tra
tio
n (
vo
l. %
, d
ry b
as
is)
0
20
40
60
80
100
CO2
CO
H2
CH4
Temperature 900ºC
1 2 3 4 5
Co
mb
us
tio
n e
ffic
ien
cy,
c (
%)
50
60
70
80
90
100
Engine oil 800ºC
Engine oil 900ºC
Results
18
In accordance with the results obtained, engine oil performed better
despite its greater difficulties to be handled.
Thus, long term tests and a comprehensive OC characterization were
done to analyze deeper the influence of impurities
Results
19
LONG TERM TESTS - ENGINE OIL
• 50 h burning fuelCarefull assessment of thecombustion process
• Combustion efficiency wasunaffected by operationhours/impuritiesFor a given φ value, almost same ηc
was achieved at different operationhours
• Effect of SThe OC did not show any sign ofdeactivation or poisoning
1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
Co
mb
us
tio
n e
ffic
ien
cy,
c
(%
)
70
75
80
85
90
95
100
Engine oil
Long term tests
Temperature 900ºC
24 h
20 h30 h7 h
3 h50 h
40 h
Results
20
• Reactivity tests in TGA
Fresh and used OC particles weresubjected to succesive redox cyclesto study its evolution duringoperation
• Conversion VS time curves
As shown, OC reactivity was hardlyaffected by operation hours or thepresence of impurities
LONG TERM TESTS - ENGINE OIL
Time (seconds)
0 20 40 60 80 100 120
So
lid c
on
vers
ion
0,0
0,2
0,4
0,6
0,8
1,0
Fresh
Used
Temperature 950ºC Patm 15% vol. CH4 as reducing gas
Results
21
• SEM-EDX analyses
Particles were rounded due tooperation hours in ICB-CSIC-liq1.
Fe distribution was homogeneousalong the cross section, both onfresh and used.
Regarding possible deposition of impurities on the particles, no significant amount of none of themwere detected.
Fresh particles After 50 h
LONG TERM TESTS - ENGINE OIL
dp ( m)
0 50 100 150 200
a.u
.
Fe
dp ( m)
0 50 100 150 200
a.u
.
Mg
Ca
Ba
Zn
Pb
S
P
Fe
Results
22
Ф =FFe2O3b∙Ffuel
• 200 h successful operation
During the experimental campaign200 h were achieved with the samebatch of particles
• Results summary
ηc obtained values provide a quick overview of the mainfindings. EtOH and diesel followed thesame trend but engine oilbehaved contrary to expectationsbetter than the others at low φvalues likely due to the differentthermal decompositionmechanism
SUMMARY
1 2 3 4 5
Co
mb
us
tio
n e
ffic
ien
cy,
c
(%
)
50
60
70
80
90
100
EtOH
Diesel
Engine oil
Temperature 900ºC
23
4. Conclusions
Conclusions
24
• Three different liquid fuels, ethanol, diesel and engine oil, were evaluated in a 1kwth CLC continuous unit using a Fe- based oxygen carrier prepared byimpregnation method.
• A total of 200 hours of operation were successfully accomplished with the samebatch of Fe20-γAl2O3 particles
• The three liquid fuels behaved properly under CLC conditions working with Fe20-γAl2O3 oxygen carrier
• The behavior of engine oil was especially noteworthy as it was able to achieveeven better combustion efficiencies at low φ values despite its greater molecularcomplexity
Thanks for attending this presentation
Anabel Serrano
Instituto de Carboquímica, CSIC-ICB
Combustion and Gasification group
Zaragoza, Spain
Acknowledgements
This work partially supported by the Spanish Ministry for Science and Innovation (MICINN project ENE2011-26354) and the EuropeanRegional Development Fund (ERDF) and by the Government of Aragón (Spain, DGA Ref. T06). A. Serrano also thanks the Spanish Ministry of Economy and Competitiveness for the F.P.I fellowship.
Chemical Looping Combustion with liquid fuels in a 1 kWth unit using Fe- based oxygen carriers