Download - Thesis Defense Presentation 05/02/2016
High Pressure Steam Reactivation of Calcium Oxide (CaO) Sorbents For Carbon Dioxide (CO2) Capture
Using Calcium Looping ProcessMasters’ Thesis Defense
By
Amoolya Dattatraya LalsareAdvisor: Prof. Liang-Shih Fan
2
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
• Introduction
• Experimental Methodology
• Results and Discussions
• Conclusions
• Future Work
3
Energy Outlook and Carbon Emissions in the US
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
Current CO2 levels in the atmosphere1:405 ppm
In 2013, CO2 accounted for 82% of greenhouse
gas emissions in the US2
Electricity production accounts for 37% of all
CO2 emissions and 31% of all greenhouse gas
emissions2
Coal and natural gas used as fuel for atleast
66% of total electricity generated in the US in
20153.
Figure: United States Electricity Generation by Fuel TypeTr
illio
n K
W-h
our
1. Trends in Atmospheric CO2-NOAA2. Electricity in the United States - U.S. EIA
4
Latest U.S. EPA regulation for CO2 capture3:
1400 pounds CO2/MW-hour gross for new coal fired power plants
1000 pounds CO2/MW-hour gross for new natural gas power plants
Minimum 20% CO2 capture
EPA’s best system for emission reduction3:
Supercritical pulverized coal unit with partial carbon capture and storage
Need for 400-1000 pounds CO2 capture from existing and new coal fired power
plants in the US3
A viable post-combustion carbon capture technology needed to meet U.S. emission
goals
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
Energy Outlook and Carbon Emissions in the US
3. U.S. Environmental Protection Agency, Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units, Part III, 80, (2015)
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Existing Carbon Capture Technologies
Prof. L.–S. Fan’s Chemical Looping and Particle Technology Laboratory
Carbon capture efficiency: ~85%80-100% more than COE without capture4
Amine based carbon capture technology
Pre-combustion capture using oxy-combustion
Post-combustion capture using oxy-combustionCarbon capture capacity: up to 95%Cost of electricity (COE): 60% more
than COE without capture5 4. Dutcher, B., Fan, M. & Russell, ACS Appl. Mater. Interfaces 7, 2137–2148 (2015)5. Oxy-combustion pre-/post-combustion CO2 capture
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Pre-combustion CO2 capture using calcium looping process
Pre-combustion CO2, H2S, HX capture6
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
Post-combustion CO2 capture using calcium looping process
6. Wang, W. et al. Ind. Eng. Chem. Res. 49, 5094–5101 (2010)
120 KWth subpilot demonsration of CCR process>90% CO2 and ~100% SO2 captureWith Ca(OH)2 based sorbent, Ca:C : 1.43
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Limitations of two-step calcium looping process
Wt.
capt
ure
% (g
CO
2/g C
aO)
Time (min)
Maintaining sorbent reactivity and recyclability
Minimizing solid circulation rates
Loss of reactivity due to ‘sintering’ effect
on the sorbents
Sorbent regeneration is essential to
maintain CO2 capture capacity at 50-60
wt. %.
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
Fig.: Loss of reactivity during multiple CCR cycles for PG Graymont limestone tested in Pyris1 TGA at 700oC calcination 30 min and carbonation under 10% CO2
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60 wt.%
22 wt.%
7. Fu-Chen Yu, Nihar Phalak, Zhenchao Sun, and Liang-Shih Fan, Industrial Chemical Engineering Resources, 2012, 2133-2142
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Reactivation of calcium oxide(CaO) Sorbents
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
•Derived from calcium acetate, calcium propioniate, calcium D-gluconate•PCC sorbent used in OSCAR process8
Synthesis of calcium based sorbents from different precursors
•Zr, Si, Ti, Cr, Co, Ce doped9
•Natural dolomitic limestone (CaO-MgO)
Doped or supported
calcium oxides
•High temperature steam reactivation7
•Water hydration
Steam hydration reactivation of calcium oxide
sorbents
8. Fan, L.-S. & Jadhav, R. A. AIChE J. 48, 2115–2123 (2002)
9. Li, Z., Cai, N., Huang, Y. & Han, H. Energy & Fuels 19, 1447–1452 (2005)
7. Yu F.-C., Phalak N., Sun, Z., and Fan, L.-S., Ind Chem Eng Res, 2012, 2133-2142
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Steam hydration reactivation
HyPr-RING Process10
CaO + H2O Ca(OH)2 ∆Ho= -
109 KJ/mol
Steam hydration was first in proposed for flue gas
desulfurization (FGD) process
Used in H2 Production-RING process for hydrogen
production
Steam hydration was also used in CO2 acceptor
process11
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
10. Lin, S. Y., Suzuki, Y., Hatano, H. & Harada, M. Energy Conversion
Management 43, 1283–1290 (2002) 11. Curran, G. P., Rice, C. H. & Gorin, E. Carbon Dioxide Acceptor Gasification Process
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What operating conditions should be used for steam
hydration reactivation of sorbents?
How can the exothermic hydration reaction be
integrated into the existing two step carbonation
calcination process?
What residence times should be used for hydration?
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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490 500 510 520 530 540 5500.30.60.91.21.51.82.12.42.7
Temperature (oC)
PH2O
(atm
)
CaO + H2O Ca(OH)2
P*H2O = 0.88
P*H2O = 1.064
P*H2O = 1.28
P*H2O = 1.53
High temperature high pressure steam hydrationReaction Properties Steam hydration of CaO is
thermodynamically limited reaction
Rate α (PH2O – P*H2O)n
Easily reversible at T>350oC with no
steam contact
Thus Ca(OH)2 is directly sent to the
carbonator
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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Steam hydration for PH2O < 1 atm, rate of hydration is slow if operated too close
to equilibrium steam partial pressure Wang et al investigated effect of Japanese limestones for steam partial
pressures between 13-23 atm 12. Wang, Y., Lin, S. & Suzuki, Y. Fuel Process. Technol. 89, 220–226 (2008)
Lin et al13 performed steam hydration at high temperatures 500-650oC and steam
partial pressures 6.7-21 atm
Rate of hydration α (PH2O – P*H2O)2
Second order reaction at high temperature and steam pressure
Activation energy: 8.4 KJ/mol of CaO
High temperature high pressure steam hydration
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
13. Lin, S., Harada, M., Suzuki, Y. & Hatano, H. Energy and Fuels 20, 903–908 (2006)
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Steam hydration reactivation studies at OSU Three step CCR process includes steam hydration at atmospheric steam
pressure and temperature 475-512oC
ASPEN process simulations of the CCR process retrofit to a 500 MWe unit with
subcritical PC boiler recommends high temperature-moderate pressure steam
reactivation12 12. Wang, W., Ramkumar, S., Wong, D. & Fan, L.-S. Fuel 92, 94–106 (2012)
This study investigates reaction kinetics using Intermediate reaction temperatures: 500-550oC
Elevated steam pressures: 1 to 4.5 atm
Effect of origin of the sorbent on reactivity towards steam
Effect of sorbent morphology on steam hydration reactivation
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
Investigation of high temperature – high
pressure steam hydration was performed
using following type of experimental
methods and design
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Limestone Precursors and Sorbent Properties
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
PG FL EA AA0
10
20
30
40
50
60
70
80
90
100
%CaCO3
%CaCO3 %Ca(OH)2
Calcination performed in Fisher Scientific Muffle Furnace
Calcination performed at 900oC for 2 hours
Preliminary analysis of limestone sorbents performed on Pyris 1
TGA
Weight loss during isothermal decomposition to calculate extent
of calcination and hydration
%CaCO3 =
%Ca(OH)2 =
20
Nitrogen physisorption studies Braunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH)
method used to obtain surface area and pore volume of the sorbents
Sorbents were used in four conditions: original (mostly CaCO3),
calcined sorbent (c-CaO), hydrated sorbent (mostly Ca(OH)2),
hydrated sorbents degassed at 400oC (h-CaO)
Degassing was performed at 200-400oC under vacuum for atleast 8
hours to obtain a clean and moisture free surface for analysis
Analysis was performed using N2 adsorption-desorption in liquid
nitrogen bath (-196oC)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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Experimental design and type of reactor Parametric steam hydration studies performed
using high pressure in the TGA
Rubotherm Magnetic Suspension Balance
(MSB) was used for this purpose
System pressurized using back pressure
regulator under elevated pressures (1-4.5 atm)
Steam injection using a preheater section before
the reactor
Water delivered to the preheater using a high
precision syringe pump
All tests performed on PG sorbent Calcination temperature: 700oC Inert atmosphere for calcination 50% steam – 50% N2 for hydration Sample size: 120-150 mg
Thermogravimetric analysis
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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Fixed Bed Experimental SetupExperimental design and type of reactor Ceramic tube reactor system with quartz
container
Heated using tubular electric furnace MTI
Corporation GLX 1000
Air-CO2 mixture was used for calcination of
sorbents to simulate equilibrium conditions for
calcination
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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Results and Discussions
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
Results and Discussions
24
BET Surface area and pore volume studies using liquid nitrogen
0
0.05
0.1
0.15
0.2
0.25
PG FL EA AA
POR
E V
OLU
ME
(cc
g-1)
Original – CaCO3 rich limestone samplec-CaO – Sorbent obtained from calcination in muffle furnace (CaCO3 = CaO + CO2)Hydrated – Ca(OH)2 from water hydration of c-CaOh-CaO – Sorbent derived by dehydration
Original c-CaO Hydrated Degassed
150C
h-CaO (Degassed
400C)
0
10
20
30
40
50
60
70
80
90
100
FL PG AA EA
Surfa
ce A
rea
(m2
g-1)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
25
Reaction Kinetics Studies in the TGA
Temperature(oC)
Steam pressure (PH2O) (atm)
500 1.5, 2.0, 2.25, 2.5
510 2.25
520 2.0, 2.25, 2.5, 3.0, 3.5
530 2.0, 2.2, 2.4, 2.6, 2.8, 3.0
Experimental design and reaction conditions Rubotherm Magnetic Suspension Balance
(MSB) was used for this purpose
Reactions conditions based on the process
simulations of the CCR process
Reaction temperature comparable to carbonator
With moderate steam partial pressures, higher
hydration conversion observed at each operating
condition
Reaction time 2 – 12 minutes
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
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Effect of temperature
0 1 2 3 4 5 6 7 8 9 100%
10%20%30%40%50%60%70%80%90%
100%PH2O = 2.0 atm
500 degC 520 degC 530 degC
Time (minute)
Conv
ersi
on (X
)
PG sorbent
Steam partial pressure: 2.0 atm
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
495 500 505 510 515 520 525 530 5350
0.2
0.4
0.6
0.8
1
1.2
1.4 1.22
0.72
0.47
TRxn(oC)
(PH
2O –
P*H
2O) (
atm
)
27
Effect of temperature PG sorbent
Steam partial pressure: 2.2 – 2.4 atm
0 1 2 3 4 5 6 7 80%
10%20%30%40%50%60%70%80%90%
100% PH2O = 2.2-2.4 atm
500 degC 520 degC530 degC 2.2 atm 510 degC
Time (minute)X
(%)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
495 500 505 510 515 520 525 530 5350
0.20.40.60.8
11.21.41.6
1.371.19
0.97
0.67
TRxn (oC)
(PH
2O –
P*H
2O) (
atm
)
28
Effect of temperature PG sorbent
Steam partial pressure: 2.5 atm
0 1 2 3 4 5 6 7 80.00%
10.00%20.00%30.00%40.00%50.00%60.00%70.00%80.00%90.00%
100.00%PH2O = 2.5 atm
500 degC 520 degC 530 degC
time (minute)
Conv
ersi
on (X
)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
495 500 505 510 515 520 525 530 5350
0.20.40.60.8
11.21.41.61.8 1.62
1.22
0.97
TRxn (oC)
(PH
2O –
P*H
2O) (
atm
)
29
Effect of Steam Partial Pressure
0 1 2 3 4 5 6 7 8 90.00%
10.00%20.00%30.00%40.00%50.00%60.00%70.00%80.00%90.00%
100.00%Trxn = 500oC
1.5 atm 2.0 atm 2.5 atm
time (minute)X
(%)
PG sorbent
Reaction temperature: 500oC
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.60
0.20.40.60.8
11.21.41.61.8
0.62
1.12
1.62
PH2O (atm)
(PH
2O –
P*H
2O) (
atm
)
30
Effect of Steam Partial Pressure PG sorbent
Reaction temperature: 520oC
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00% Trxn = 520oC
2.5 atm 2.25 atm 2.0 atm 3.5 atm 3.0 atmTime (minute)
X (%
)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
1.5 2 2.5 3 3.5 40
0.5
1
1.5
2
2.5
0.720.97
1.22
1.721.97
PH2O (atm)
(PH
2O –
P*H
2O) (
atm
)
31
Effect of Steam Partial Pressure PG sorbent
Reaction temperature: 530oC
0 1 2 3 4 5 6 7 8 90.00%
10.00%20.00%30.00%40.00%50.00%60.00%70.00%80.00%90.00%
100.00% TRXN = 530oC
3.0 atm 2.8 atm 2.6 atm 2.4 atm 2.2 atm 2.0 atmtime (minute)
X (%
)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.10
0.20.40.60.8
11.21.41.6
0.470.67
0.871.07
1.271.47
PH2O (atm)
(PH
2O –
P*H
2O) (
atm
)
32
0.4 0.6 0.8 1 1.2 1.4 1.60
0.00050.001
0.00150.002
0.00250.003
0.00350.004
0.0045
Rate V/s Delta P @500degC Rate V/s Delta P @520degCRate V/s deltaP @ 530 degC
PH2O - P*H2ORa
te (s
-1)
Kinetics of Steam Hydration Rate of reaction is proportional to
(PH2O – P*H2O)n
n=
Thus rate α (PH2O – P*H2O)2
Order of reaction ~ 2 k = ….Rate constant
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
33
Rate constants and Activation Energy k =
Arrhenius plot for rate constants
for steam hydration
Rate constant (k) calculated for
reaction performed at different
steam pressures at different
temperatures
Ea = 5.19 KJ/mol
1.88E-03 1.92E-03 1.96E-03 2.00E-03
-2.00E-05
3.05E-20
2.00E-05
4.00E-05
6.00E-05
8.00E-05
1.00E-04
rate constant V/s 1/T
A = 0.0002 s-1 MPa-1
Ea = 5.19 kJ/mol
Rate constant (k)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
34
Comparative TGA studies of sorbents Steam hydration of sorbents at PH2O =
1.5 atm and Temperature: 500oC
PG sorbent shows better reactivity
compared to FL, EA, and AA
PG has the highest surface area in
calcined form (c-CaO)
Rate of hydration:
PG > FL > EA > AA0 1 2 3 4 5 6 7 8 9 10 11 12 13
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
PG FL EA AATime (minute)
Conv
ersi
on (X
)
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
35
PG Fixed
bed
calcination
Air (ml/min) CO2
(ml/min)
Extent of
calcination
700oC 300 0 67.7%
800oC 240 60 76.5%
900oC 0 300 84.3%
FB 700 degC FB 800 degC FB 900 degC0
2
4
6
8
10
12
14
0.00E+001.00E-022.00E-023.00E-024.00E-025.00E-026.00E-027.00E-028.00E-029.00E-021.00E-01
Surfa
ce a
rea
(m2
g-1)
Pore
Vol
ume
(cc
g-1)
Effect of upstream calcination on sorbent morphologyCalcination performed in fixed bed
reactor using Air-CO2 mixture to
simulate equilibrium conditions
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
36
Rate of steam hydration increases with
increasing steam partial pressure
Higher conversions can be obtained using
relatively high reaction temperature (500 -
530oC) and moderate steam partial
pressures (1.5-3.5 atm)
Residence time for hydration in the TGA is
2 to 10 minutes for PG limestone
Second order reaction w.r.t steam partial
pressure (PH2O – P*H2O)
Temperature could be increased further to
550-570oC and higher steam pressure 4.5-
5.0 atm for operation in the pre-combustion
CO2 capture process
Activation energy for the reaction is 5.19
KJ/mol Better hydrator design with the available
kinetics data, Ca:C mole ratio could be
minimized with minimization of solids
circulation rate and requirement of make-up
solids
Concluding Remarks
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
37
Continuous multi-cyclic fixed bed reactor
studies using steam hydration at high
temperature and elevated steam pressure
Steam conversion and sorbent
performance can be analyzed
CO2 capture capacity will be obtained for
during carbonation in each cycle in the 15-20
cycle fixed bed studies
Heat recovery and utility from the exothermic
hydration reaction at high temperature will
be studied using ASPEN simulations of the
CCR process
Ca:C mole ratio will be obtained for current
U.S EPA regulations for minimum 20% CO2
capture
Shrinking core model prediction for steam
hydration of CaO could be investigated using
characterization techniques like depth
profiling using XPS or SIMS techniques
Future Work
Prof. L.–S. Fan’s Clean Energy Conversion Laboratory
38
Prof. L.–S. Fan’s Chemical Looping and Particle Technology Laboratory
Acknowledgements
We are grateful to Ohio Coal Research Consortium (OCRC) for their continuing financial support for clean coal conversion research projects including this.