Bench-Scale Development of a Hot Carbonate

Absorption Process with Crystallization-Enabled High

Pressure Stripping for Post-Combustion CO2 Capture

(DOE/NETL Agreement No. DE-FE0004360)

2013 NETL CO2 Capture Technology Meeting

Pittsburgh, PA July 8-11, 2013

Presenter: Yongqi Lu

Illinois State Geological Survey

Prairie Research Institute

University of Illinois at Urbana-Champaign

Prime Contractor

2

Illinois State Geological Survey (ISGS)

One of five scientific surveys at Prairie Research Institute, University

of Illinois

200 scientists and technical support staff

Lead organization of Midwest Geological Sequestration Consortium

(MGSC) Partnership

ISGS’s Applied Research Laboratory conducts carbon capture and

other energy & environmental technology researches

Project Overview

3

Project Team

Illinois State Geological Survey-University of Illinois

Bench- and lab-scale experimental studies

Nick Devries, Yongqi Lu (PI), David Ruther,

Manoranjan Sahu, Qing Ye, Xinhuai Ye, Shihan Zhang

Carbon Capture Scientific, LLC Risk analysis and techno-economic studies

Scott Chen, Zhiwei Li, Kevin O’Brien (Sub-PI)

DOE/NETL (Funder) Project manager - Andrew Jones

Illinois Clean Coal Institute (Co-Funder) Project manager – Joseph Hirschi

4

Project Performance Dates and Budget

Project duration: 39 months

BP1: 1/1/11- 12/31/11

BP2: 1/1/12 - 3/31/13

BP3: 4/1/13 - 3/31/14

Budget

5

Budget, $

DOE/NETL 1,291,638

ICCI (cash) 201,000

UIUC (in kind) 134,357

CCS, LLC (in kind) 47,713

Total 1,674,708

(Cost share: ~23%)

$0

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

BP1 BP2 BP3

Bud

ge

t, $

DOE

ICCI

UIUC

CCS,LLC

Project Objectives

Perform a proof-of-concept study aimed at generating

process engineering and scale-up data to help advance the

proposed CO2 capture process to a pilot-scale demonstration

level upon completion of the project

ISGS/UIUC team: Lab- and bench-scale tests to generate

thermodynamics and reaction engineering data for major

unit operations

CCS, LLC team: Technical risk mitigation analysis and

techno-economic studies

6

7

Technology Fundamentals/Background

8 8

Hot Carbonate Absorption Process with High Pressure Stripping

Enabled by Crystallization (Hot-CAP)

Absorption into 30-40wt% potassium carbonate (PC) solution at 60−80 C

Working capacity of PC: 15/20% to 40/50% carbonate-to-bicarbonate (CTB) conv.

Crystallization at near room temperature (~30 C)

Stripping of bicarbonate slurry at ≥10 atm

Steam from

IP Turbine

Hydro

cyclone

Flue gas

Cleaned

flue gas

Absorption

column

(60-80 C)

K2CO3/KHCO3

rich Solution

(40-50% CTB)

High

Pressure

Stripper

( 140 C)

Reboiler

High Pressure

CO2 ( 10 atm)

Crystallization

Tank

(30-35 C)

SO42-

Removal

Slurry pump

Cross heat

exchanger

Cross heat

exchanger

K2CO3/KHCO3

lean Solution

(40%wt PC-eqv.,

15-20% CTB)

KHCO3 slurry

( 50%wt)

K2CO3/KHCO3

semi-lean Solution

( 70% CTB)

9 9

Major Reactions

33222

2

2

:8060

KHCOCOKOHCO

CatabsorptionCO

)(

:30

33 sKHCOKHCO

CatationCrystalliz

32223

2

)(

:130

COKOHgCOKHCO

CatdesorptionCO

CO2

Absorption

Bicarbonate

crystallization High

pressure

strippingCO2-rich

K2CO3/KHCO3

CO2-lean

K2CO3/KHCO3

KHCO3

slurry

Regenerated

K2CO3/KHCO3

Flue

gas

Clean

gas

CO2/H2O

Liquid-solid

separation

Advantages of Hot-CAP over Conventional MEA

10

High stripping pressure

low compression work

low stripping heat (high CO2/H2O ratio)

Low sensible heat

Comparable stripping working capacity to MEA

Lower Cp (60% of MEA)

Low heat of absorption

18 kcal/mol CO2 (crystallization heat included) vs. 21 kcal/mol for MEA

Items MEA Hot-CAP

Solvent 30wt% MEA 30-40wt% K2CO3

Solvent degradation Y N

Corrosion Y Less significant

Absorption temperature 40-50 C 60-80 C

Stripping temperature 120 C 130-200 C

Stripping pressure 1.5-2 atm ≥10 atm

Phase change bw absorb. and stripping N Crystallization

FGD required Y N

Technical Risks/Challenges to Be Addressed

A. Is overall rate of CO2 absorption into PC comparable to 5M MEA?

B. Can CO2 stripping operate at high pressure (e.g. 10 bar)?

C. Can fouling risk due to bicarbonate precipitation on surfaces of heat exchangers

and crystallizer coolers be prevented?

D. Is crystallization rate fast enough (e.g., residence time of <1 hr)?

E. Can the stripper be designed to handle slurry while operating at high pressure?

F. Can SO2 removal be combined in Hot-CAP?

11

Steam from

IP Turbine

Hydro

cyclone

Flue gas

Cleaned

flue gas

Absorption

column

(70-80 C)

K2CO3/KHCO3

rich Solution

(40-50% CTB)

High

Pressure

Stripper

( 140 C)

Reboiler

High Pressure

CO2 ( 10 atm)

Crystallization

Tank

(30-35 C)

SO42-

Removal

Slurry pump

Cross heat

exchanger

Cross heat

exchanger

K2CO3/KHCO3

lean Solution

(40%wt PC-eqv.,

15-20% CTB)

KHCO3 slurry

( 50%wt)

K2CO3/KHCO3

semi-lean Solution

( 70% CTB)

Steam from

IP Turbine

Hydro

cyclone

Flue gas

Cleaned

flue gas

Absorption

column

(70-80 C)

K2CO3/KHCO3

rich Solution

(40-50% CTB)

High

Pressure

Stripper

( 140 C)

Reboiler

High Pressure

CO2 ( 10 atm)

Crystallization

Tank

(30-35 C)

SO42-

Removal

Slurry pump

Cross heat

exchanger

Cross heat

exchanger

K2CO3/KHCO3

lean Solution

(40%wt PC-eqv.,

15-20% CTB)

KHCO3 slurry

( 50%wt)

K2CO3/KHCO3

semi-lean Solution

( 70% CTB)

A

B, E

C

C

D

F

12

Progress and Current Status of Project

Project Major Tasks, Progress and Millstones Achieved

13

Project Tasks Progress to date

Task 0. Project planning & management In progress

Task 1. Kinetics of CO2 absorption

• Absorption with and w/o promoters

• Absorption column tests

Completed

(Supplementary tests (with Na2CO3) in progress)

Task 2. Crystallization kinetics & solubility of

bicarbonate

• KHCO3 crystallization tests

• NaHCO3 crystallization tests

Completed

Task 3. Phase equilibrium & kinetics of high

pressure CO2 stripping

• VLE measurements

• Stripping column tests

VLE completed;

Column tests in progress

Task 4. Reclamation of sulfate from SO2 removal

• Semi-continuous reclamation tests

• Process modification/improvement

Proof-of-concept tests completed;

Tests on process improvement in progress

Task 5. Techno-economic evaluation

• Risk mitigation analysis

• Process simulation

• Economic evaluation

Risk analysis completed;

Economic evaluation in progress

Currently in 1st quarter of BP3

17 milestones in BP1 and BP2

16 milestones completed on schedule

1 milestone extended for 3 months

CO

2part

ial p

ress

ure

Time

CO

2part

ial p

ress

ure

Time

(1) Studies of CO2 Absorption:

Promoter Screening Tests Using a Stirred Tank Reactor (STR)

Instant rate of CO2 absorption:

(PrC: pressure controller; TC: thermal couple;

PG: pressure gauge; DAQ: data acquisition)

GL

gCOCO

ATR

V

dt

dPJ 2

2

14

TC

Screening tests using STR:

3 inorganic and 8 organic promoters

3 promoters selected for packed bed

column testing

CO2 Absorption Column Tests: Experimental Setup

15

Specification

Column height, m 10 ft

Packed bed height 7 ft

Absorber diameter, cm 4 in

Height of packing element 4 in

Diameter of packing element 4 in

Specific surface area 800 m2/m3

Void fraction (ε) 0.66

CO2

analyzer

Vent

CO2

cylinder

Air

compressor Solution

discharge

Column

Humidity

meter

Steam

generator

s

s

s

s

TC

s

s

s

s

TC

s

s

s

s

TC

s

s

s

s

TC

s

s

s

s

TC

s

s

s

s

FM s

s

s

s

FM

s

s

s

s

FM

s

s

s

s

Pr

s

s

s

s

Pr

Structured

packing

TC: Thermal couple

Pr: Pressure measure

FM: Flow meter

TCtr: Temperature

controller

Stock

Solution

discharge

Peristaltic

pump

s

s

s

s

TCtr

Heater

Dryer

Column Tests Revealed More Favorable Rate of CO2

Absorption into 40wt% PC + Promoter than 5M MEA

CO2 removal by PC40+1M DEA or 0.5M PZ at 70 C > 5M MEA at 50 C

W/o promoter, CO2 removal efficiency by 40wt% PC was insignificant

16

(70ºC absorption in 40wt% PC and 50 C in 5M MEA; inlet CO2 =14 vol%, L/G=4.7 lb/lb)

(30% CO2 removal efficiency equivalent to ~11% increase in CTB thru the column)

15 20 25 30 35 40 45 500

5

10

15

20

25

30

35

40

45

50

55 PC40+1M AMP

PC40+1M DEA

PC40+0.5M PZ

CO2 loading in MEA, mol/mol

CO

2 r

eo

mva

l e

ffic

ien

cy,

%

CTB conversion of PC40, %

0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50

5M MEA

Lean CTB conversion level in PC40, %

Lean CO2 loading in 5M MEA, mol/mol

Precipitates

occurred

(2) Studies of Bicarbonate Crystallization

A process configuration developed to address fouling risk and heat recovery:

Conventional single-crystallizer design requires a large T between inflow

and outflow, undesirable for heat recovery

Multiple crystallization tanks/modules developed with a vendor to reduce

T = ~ 5°C

17

Absorption

ColumnStripping

Column

Cross Heat

Exchanger

Filter

Cross Heat

Exchanger

70oC

175~180

oC

175~180 oC

Flue

Gas

Clean

Flue Gas

55 oC 30 oC

High

Pressure

CO2

35 oC

50~45 oC

Filter

Crystallizer

Cooling water

Cooling

water

Filter

30 oC

60 oC

60~55 oC

Filter

Crystallizer Crystallizer

55~50 oC

Crystallizer Crystallizer

35 oC

55 oC50 oC 45 oC

Filter

45 oC50 oC55 oC60 oC65 oC

50 oC 45 oC 40 oC

65~60 oC 45~35 oC

ss

Crystallization Tests in a Continuous Mixed Suspension-Mixed

Product Removal (MSMPR) Reactor

18

CO2-rich feed solution:

Temperature: 70°C

Composition: K2CO3/KHCO3

(PC40-40)

Test conditions selected to simulate

multiple-CSTR process

70-55°C

55-45°C

45-35°C

Crystallization rate constants

(nucleation and growth) determined

1-liter calorimetric CSTR (Syrris Atlas);

Crystal size distribution analysis (Horiba LA-950)

Morphology and Composition of Crystal Particles

High-purity kalicinite (KHCO3) prevailed in crystal phase

Prism-shaped (hexagonal) morphology

Yield of KHCO3 crystals consistent to its solubility at crystallization T

19

0

50

100

150

200

250

300

350

400

450

-2000

-1000

0

1000

2000

3000

4000

5000

6000

7000

10 20 30 40 50 60

Inte

nsit

y

2 theta ( )

Crystal sample from batch test 1

Standard pattern of KHCO3 # 04-013-

5503

XRD pattern of a typical kalicinite (KHCO3) sample SEM image of KHCO3 crystal (end T=45 C)

Parametric Tests Indicated Fast Crystallization of KHCO3

Crystal growth and nucleation rates measured at different agitation rates,

mean residence times (MRT, 15, 30, 45 min) and T-dependent super-

saturation levels (TSL, T=35, 45, 55 C)

Mean particle size of KHCO3 crystals under test conditions: 233-455 µm

Crystal size large enough for ~100% liquid-solid separation in

conventional hydrocyclone

Crystallization time 45 min is sufficient

20

0

50

100

150

200

250

300

350

400

450

0

1

2

3

4

5

6

7

0 10 20 30 40 50 M

ea

n c

rysta

l siz

e,

m

Gro

wth

rate

1

0-8

, m

/s,

or

nu

cle

atio

n r

ate

1

08, /m

3.s

Mean residence time, min

0

50

100

150

200

250

300

350

400

450

0

1

2

3

4

5

6

7

20 30 40 50 60

Me

an

cry

sta

l siz

e,

m

Gro

wth

rate

1

0-8

, m

/s,

or

nu

cle

atio

n r

ate

1

08, /m

3.s

Crystalization temperature, C

Growth rate

Nucleation rate

Particle size

Example 1: 70 C PC40-40 feed,

crystallization at 55 C, 350 rpm

Example 2: 70 C PC40-40 feed,

MRT=30min, 700 rpm

Growth rate

Nucleation rate

Particle size

(3) Studies of CO2 Stripping:

VLE measurement for K2CO3/KHCO3 Slurry

Gas analysis using GC and liquid analysis using a back-titration method

40-70wt% KHCO3/K2CO3 slurry at 120-200 C

21

N2

DAQParr reactor

To DAQ

TC

PrC

Temperature

controller

GC

PrT

CO2

1-liter Parr reactor

(rated at 1,900 psi and 275 C)

VLE Results Indicated that High Stripping Pressure is

Thermodynamically Feasible in Hot-CAP

22

High Ptotal and low PH2O/PCO2 ratio attained

Higher Ptotal and lower PH2O/PCO2 ratio at higher temperature, CTB

conversion, or PC concentration

40wt% PC

(K2CO3-equiv.) 50wt% PC 60wt% PC

CO2 Stripping Experimental System

Stripping column: 7 ft high x 1 in ID; 3 kW electrically heated reboiler

Slurry supply tank: 10 gallon vol., 5 kW electrical heater

Control panel and monitoring (T, P, rpm, flow rate, etc.)

System rated at 200 C and 500 psia

23

Stripping

column

Solution

supply tank

High-P/T

liquid meter

Reboiler

Vent

CO2

cylinder

Water

knockout

Stripping

Column

Humidity

meter

s

s

s

s

T

s

s

s

s

T

s

s

s

s

T

s

s

s

s

P

s

s

s

s

P

T: Thermal couple; P: Pressure transducer; FM: Flow meter

TCr: Temperature controller; PR: pressure rupture disk; PCr: pressure regulator;

BPCr: back pressure controller

Discharge

container

s

s

s

T

s

s

s

s

T

s

s

s

s

~

s

r

s

s

s

TCr s

s

s

s

PCr

s

s

s

s

P s

s

s

s

TCr s

s

s

s

FM ss

ss

BPCr

s

s

s

PR

Reboiler heater

with Amp and

Volt recorder

Liquid level

controller

Controller

s

s

s

s

FM

Reflux

condenser

Data

logger

T, P monitoring

& control;

Liquid level

control

High pressure

stirred tank

Packing

Control panel

Display meters

Initial Results Indicated Good Performance of CO2 Stripping

Even with Less Concentrated Feed Slurry

Initial results with relatively low concentration slurry (30-50 wt%) confirmed that high Ptotal and low PH2O/PCO2 were possible

Increasing feed CTB% conversion and reboiler temperature favored performance of CO2 stripping

Parametric tests in progress to investigate:

Effects of CTB% in feed, slurry concentration, stripping T, slurry flow rate, etc. 24

Temperature

in reboiler (oC) Rich solution* Lean solution

Feed flow rate

(LPM)

CO2 flow rate

(ml/min)

Ptotal in column

(psia)

140 PC40-40 PC40-33 0.1 660 39

160 PC40-40 PC40-20 0.1 2,022 81

160 PC30-60 PC30-54 0.1 270 89

140 PC32-80 PC32-55 0.1 1,900 69

170 PC32-80 PC32-48 0.1 2,435 97

180 PC50-60 PC50-48 0.1 1,700 108

* PC X-Y stands for X wt% K2CO3-equivalent concentration and Y% carbonate-to-

bicarbonate (CTB) conversion

(4) Reclamation of Sulfate for SO2 Removal in Hot-CAP:

Process Proof-of-Concept Tests

25

SO2 absorption into PC:

K2SO4 reclamation process:

Reaction with lime:

Competitive reaction:

Inhibition by high-P CO2:

2422232 2/1 COSOKOSOCOK

)(22 24322242 OHCaSOCOKCOOHCaOSOK

)(3

2

3

2 CaCOCOCa

)()()( 23223 aqHCOCaOHCOsCaCO

Semi-continuous experimental results :

Precipitates: gypsum (0-58wt%), syngenite (0-

91%), vaterite/calcite (0-100%)

Precipitates from most tests contained >30%

vaterite/calcite

Precipitation of CaSO4 favored over CaCO3 at

lower T or lower PC concentration Example: XRD of precipitates from three

PC-0.4M K2SO4-0.4M CaCl2 systems.

A Modified Process Option for K2SO4 Reclamation

Tests of K2SO3 oxidation and

K2SO4 precipitation in progress

26

Major reactions:

Absorption: 2K2CO3 + SO2 +H2O K2SO3 + H2CO3;

2KHCO3 + SO2 +H2O K2SO3 + 2H2CO3

Oxidation: K2SO3 + ½ O2 K2SO4 (s)

Reclamation: K2SO4 + Ca(OH)2 2KOH + K2SO4 (s)

Solubility:

K2SO3, K2CO3, KHCO3 >> K2SO4

Solubility of K2SO4

Solubility of K2SO3

K2SO4 slurry

Lime

Hydration

Forced

oxidation

Liquid/solid

Separation

CO2

Absorption

CO2

Desorption

CO2 Drying/

Dehydration

Lime Gypsum Compressed

CO2

Heat

exchanger

Flue gas

Clean

flue gas

CO2 lean

solution CO2 rich

solution

CO2/H2O

stream

Compressor

Condenser &

Vacuum pump Steam

from LP

Water

condensate to

power plant

Re-dissolution

& Reclamation

SO2 Scrubbing

CO2 lean/SO2

lean solution

Liquid/solid

Separation

Air CO2 rich/SO2

lean solution

(5) Techno-Economic Analysis:

Process Simulation and Sizing of Columns Using ProTreat

773 MWe power plant (gross w/o CO2 capture) equipped with Hot-CAP

27

Absorption

Column

Stripping

Column

Cross Heat

Exchanger #1

Cross Heat

Exchanger #2

60 o

C 123.5 o

C

Flue Gas

665t CO2

356t H2O

2159t N2

Clean Flue Gas

66t CO2

637t H2O

2159t N2

69 o

C

118 oC

5144t K2CO3

1830t KHCO3

1378t PZ

8350t H2O

Total 16702t/hr

748t K2CO3

1043t KHCO3

316t PZ

1793t H2O

Total 3900t/hr

35 oC

46 o

C

Crystallizer

Crystallizer

2517t K2CO3

1159t KHCO3

1062t PZ

6031t H2O

Total 10769t/hr

Make-up water

551t H2O

748t K2CO3

4227t KHCO3

316t PZ

1793t H2O

Total 7084 t/hr

KHCO3 2351t/hr

P-3

P-15

2517t K2CO3

3510t KHCO3

1062t PZ

6031t H2O

Total 13120t/hr

KHCO3 833t/hr

2627t K2CO3

1504t KHCO3

316t PZ

1768t H2O

Total 6104 t/hr

2627t K2CO3

671t KHCO3

316t PZ

1768t H2O

Total 5271 t/hr

35 oC

65 o

C

65 o

C

70 o

C

141 o

C

55 o

C

115 o

C

Cross Heat

Exchanger #3

Cooling

water

CO2 product gas

599t CO2

276t H2O

Total 875t/hr

123.5 o

C

65 o

C

Reboiler

110 oC

314.6 MWth

(steam)

113.6 MWth

(steam)

72.8 MWth

355.4 MWth

-30.3 MWth

-287.9 MWth

229.9 MWth

Preliminary Results of Process Simulation and Sizing

Column sizing:

2 absorbers, each of 14.7-m ID x 25-m height

1 stripper, 7.3-m ID x 10-m height

Packed with Mellapak M250.Y

Energy performance:

28

CO2 Stripping (kWh/ kg CO2) 0.155

Compression work (kWh/ kg CO2) 0.075

Other loads (kWh/ kg CO2) 0.04

Total electricity use (kWh/kg CO2) 0.27

Current simulation based on a low stripping P (2 bar) due to lack of data at

T>140 C in ProTreat software

Higher stripping P and better energy performance expected at T>140 C

due to high adsorption + crystallization heat (~18 kcal/mol)

High stripping-P scenarios (>>2 bar) will be simulated by incorporating

measured VLE data into software

29

Plans for future testing/ development/

commercialization

Work Plan in BP3

High pressure CO2 stripping tests

Stripping performance tests

Stripping process optimization

Proof-of-concept testing of a modified process option for combined SO2

removal and CO2 capture

Techno-economic studies

Process optimization study

Equipment sizing and cost analysis

30

Technology Scale-up Development

Process optimization and improvement to reduce technical risks and

enhance performance

Detailed techno-economic analysis

If technically and economically viable,

Seek federal, state, and industrial support for a pilot-scale test (0.5-3

MWe)

Identify industrial partners (design, manufacturing and field testing) for

pilot-scale demonstration

31

Acknowledgements

U.S. Department of Energy/ National Energy Technology

Laboratory under Agreement No. DE-FE0004360

Illinois Department of Commerce and Economic Opportunity

through the Office of Coal Development and the Illinois Clean

Coal Institute under Project No. 11/US-6

32