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


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

http://www.esrl.noaa.gov/gmd/ccgg/trends/



http://www.eia.gov/energyexplained/index.cfm?page=electricity_in_the_united_states

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


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)

7

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

http://www.ccsassociation.org/what-is-ccs/capture/oxy-fuel-combustion-systems



8

Pre-combustion CO2 capture using calcium looping process

Pre-combustion CO2, H2S, HX capture6


9


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

10

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. %.


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

7

60 wt.%

22 wt.%

7. Fu-Chen Yu, Nihar Phalak, Zhenchao Sun, and Liang-Shih Fan, Industrial Chemical Engineering Resources, 2012, 2133-2142

11

Reactivation of calcium oxide(CaO) Sorbents


•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

12

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


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

13

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?


14

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


15

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


13. Lin, S., Harada, M., Suzuki, Y. & Hatano, H. Energy and Fuels 20, 903–908 (2006)

16

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


17


Investigation of high temperature – high

pressure steam hydration was performed

using following type of experimental

methods and design

18

Limestone Precursors and Sorbent Properties


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)


21

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


22

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


23

Results and Discussions


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)


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


26

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


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

(%)


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

)


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


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


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 (%

)


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


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 (%

)


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


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)


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

)


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


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


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


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.