Srivats Srinivasachar and Teagan Nelson Envergex … Library/Events/2017/co2 capture...Background -...
Transcript of Srivats Srinivasachar and Teagan Nelson Envergex … Library/Events/2017/co2 capture...Background -...
Background - CO2 Capture
Attrition Evaluation of Oxygen-Carriers in Chemical Looping Systems Srivats Srinivasachar and Teagan Nelson
Envergex LLC
Johannes Van der Waat, Harry Feilen, Daniel Laudal, Michael Mann, and Steven Benson Institute for Energy Studies, University of North Dakota
Chemical-Looping-Combustion (CLC) is an innovative power generation technology for carbon capture at a lower cost and higher efficiency than state-of-the-art
• Near-pure CO2 stream produced without using oxygen from air separation • Solid oxygen-carrier (OC) used to provide oxygen to fuel • Oxygen-depleted solids regenerated separately in air • Solid oxygen carriers undergo attrition and loss of reactivity over time • Loss due to attrition and loss of reactivity creates significant operating cost burden
Project Objectives and Approach Methodology Objectives • Address critical element of CLC - loss of OC due to attrition/reactivity degradation • Evaluate attrition characteristics of oxygen carrier materials under high temperature,
reacting conditions to establish correlations between process parameters Methodology • Basis - existing standard, (ASTM D5757), used for determining attrition characteristics
of powdered catalysts by air jets • Incorporate modifications to attain test protocol more representative of chemical
looping process conditions
Experimental Setup
Temperature 800-1000°C Oxidation Composition 90% N2 , 10% O2 Oxidation Cycle Time 4 minutes Purge Composition 100% N2 Purge Cycle Time 2 minutes Reduction Composition 95% N2 , 5% H2 /CO/CO2
Reduction Cycle Time 4 minutes Test Duration (No. Cycles) 500 minutes (~50 cycles)
Evaluated multiple oxygen carriers at baseline conditions Ilmenite (2), Hematite, Red Mud, CaSO4-
based, MnOx-ore, Engineered iron oxide Cyclic operation between reduction and
oxidation conditions Measured reduction/oxidation gas
concentrations at reactor outlet
Measure attrition rate by collecting and weighing attrited material Examine the effects of varying jet velocities on the attrition of the oxygen-carriers Evaluate use of coal as fuel for reduction step on performance of selected oxygen carriers
Evaluation Strategy
Results - Evaluation Tests Ilmenite and Calcium-Based oxygen carriers had lowest attrition rates. Iron-Based-Engineered oxygen carrier had highest rate of attrition. Hematite displayed a significant breakage event during testing; thereafter attrition rate
decreased. Red Mud and Mn-Oxide-Based materials exhibited attrition rates that were slightly increasing or
relatively stable over entire test period.
Results – Effect of Gas Composition on OC Performance
Future Work Effect of operating parameters on attrition
and reactivity will be characterized to develop knowledge database and formulate strategies for commercial test service offerings. Expansion of work to study effect of
cyclonic/impaction conditions on attrition and reactivity characteristics of Oxygen Carriers. materials.
Conclusions Methodology: effective tool to down-
select oxygen carriers based on attrition propensity and reactivity Successful coal injection tests illustrate
application of attrition setup as a valuable tool for future CLC research.
Acknowledgements Contact Details Srivats Srinivasachar, Envergex LLC Phone: (508) 347-2933; Mobile: (508) 479-3784; E-mail: [email protected]
CLC reaction commenced quickly as CO and CO2 is formed immediately upon injection of lignite coal. Formation of CO2 confirms CLC reaction, as no oxygen was fed to the reactor. The oxygen carrier and steam were
sources of oxygen for reaction
↑Ilmenite- attrition, under differing reducing gas compositions
↑Ilmenite- reactivity performance
Project Manager: John M. Rockey, DOE STTR; DE-SC0011984
Results – Effect of Manufacturing Conditions
Results – OC Performance with Solid Fuel Combustion
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
698 703 708 713 718 723
Gas
Con
cent
ratio
n (%
Vol
ume)
Time (min.)
% CO2% CO% H2% CH4% O2
Reduction (Coal Injection)
Oxidation
Degree of reduction affected attrition and reactivity performance • Increasing CO/H2 concentration resulted in better fuel utilization indicating higher reduced
state of OC • Increasing CO/H2 concentration caused agglomeration (20% - 30% concentration) • Degree of reduction critically important
Reactivity of different OC’s at same test conditions
0%10%20%30%40%50%60%70%80%90%
100%
0 1 2 3 4 5 6
Cum
ulat
ive
CO2 r
elea
se p
er to
tal
avai
labl
e ca
rbon
Time (min.)
Fe_3 @ 820 °C
102030
Stable reactivity
0.0
0.2
0.4
0.6
0.8
1.0
1.2
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2.0
0 100 200 300 400 500 600
Attr
ition
Rat
e (%
/hou
r-w
eigh
t/in
itial
w
eigh
t)
Time (min.)
OC sintered at 1300 °COC sintered at 1250 °C
0.00
0.05
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0.15
0.20
0.25
0.30
0.35
0 200 400 600 800
Attr
ition
Rat
e (%
/hou
r-w
eigh
t/in
itial
w
eigh
t)
Time (min.)
10% CO and 10% H220% CO and 20% H230% CO and 30% H2
↓ Ilmenite - PSD of pre- and post-run samples
Effect of sintering on OC performance • The attrition rate between the two samples exhibited similar trends • Manufacturing (Sintering) at higher temperature caused a decrease in reactivity
↑Sintered Samples-attrition ↑Sintered Samples-reactivity
↓ Attrition- different OC’s
↑ Fe-based carrier under coal injection ↕ Fe-based carrier under coal injection
0.0
0.2
0.4
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0.8
1.0
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10% CO and 10% H2 20% CO and 20% H2 30% CO and 30% H2
Post
/Pre
Run
Size
Rat
io
0
1
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6
0 100 200 300 400 500
Attr
ition
Rat
e (%
/hou
r-w
eigh
t/in
itial
wei
ght)
Time (min.)
Fe_5.2
Fe_4.2
Fe_3
0%10%20%30%40%50%60%70%80%90%
100%
0 1 2 3 4 5 6
Cum
ulat
ive
CO2 r
elea
se p
er to
tal
avai
labl
e ca
rbon
Time (min.)
Fe_5.2 @ 970 °C
104055Decreasing
reactivity
0%10%20%30%40%50%60%70%80%90%
100%
0 1 2 3 4 5 6
Cum
ulat
ive
CO2 r
elea
se p
er to
tal
avai
labl
e ca
rbon
Time (min.)
Fe_4.2 @ 970 °C
104051
Increasing reactivity
97% -> 89%
98% -> 46%
99% -> 30%
78% -> 32% 88% -> 16%
89% -> 5%
0102030405060708090
100
10% 20% 30%
Aver
age
Gas C
onve
rsio
n pe
r cyc
le
(%/c
ycle
)
Reducing Gas Composition
H2CO
Starting and end conversion per cycle
↓ Ilmenite - Average Gas Conversion per cycle
0%
10%
20%
30%
40%
50%
60%
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90%
100%
0 100 200 300 400 500 600
(Act
ual f
uel c
onsu
mpt
ion)
/(Th
eore
tical
fu
el c
onsu
mpt
ion)
Time (min.)
30% CO and 30% H220% CO and 20% H210% CO and 10% H2
0%
10%
20%
30%
40%
50%
60%
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80%
90%
100%
0 10 20 30 40 50
Fuel
con
vers
ion
(%)
Time (min.)
H2 (Sintered at 1250 °C)H2 (Sintered at 1300 °C)CO (Sintered at 1250 °C)CO (Sintered at 1300 °C)