Evaluation of Carbon Dioxide Capture From Existing Coal Fired Plants by Hybrid Sorption Using Solid Sorbents (CACHYSTM)
NETL CO2 Capture Technology Meeting
Pittsburgh, Pennsylvania July 29-Aug 1, 2014
Steve Benson, Dan Laudal, Harry Feilen, Kirtipal Barse, Scott Johnson
University of North Dakota – Institute for Energy Studies
Srivats Srinivasachar Envergex LLC
Presentation Overview
2
Project Overview
Technology Fundamentals
Progress and Current Status
Future Plans
Funding
3
Initial Funding – STTR project – Envergex and UND
Project Funding U.S. Department of Energy Carbon Dioxide Capture RD&D program
Bench-scale testing
October 2011 to September 2014 (No-cost extension through Dec. 2014)
Total Project Funding: $3,690,000 DOE Share: $2,952,000
Cost Share: $738,000
• US Department of Energy - NETL
• UND Institute for Energy Studies
• Envergex LLC
• Lignite Energy Council/NDIC
• ALLETE Group
• Minnesota Power
• BNI Coal
• SaskPower
• Barr Engineering
• Solex Thermal Science
4
Project Participants
Project Objectives
Overall Project Objectives Improve current state-of-the-art (amine scrubbing) by developing a novel
sorbent-based, post-combustion CO2 capture technology Achieve at least 90% CO2 removal from coal combustion flue gas Demonstrate progress toward DOE target of less that 35% increase in
levelized cost of electricity (LCOE) for plant with CO2 capture Demonstrate at bench-scale level a sorbent-based technology for capture
of CO2 by hybrid sorption (CACHYS™) from coal combustion flue gas Develop key information on sorbent and technology effectiveness
5
Technology Background and Fundamentals
CACHYS™ Hybrid Sorption Process
7
• Key component – metal carbonate salt
• Reacts with CO2 to form adduct. Reversible with heat addition
• Additive/process conditions - enhance adsorption kinetics + reduce adsorption/regeneration energy
Coal-fired PlantSorbent
Treatment
CO2
Adso
rber
Rege
nera
tor
Filter Flue Gas: Low CO2
Flue Gas: High CO2
Compressed CO2
Cond
ense
r
Extraction Steam (~150oC)
HX -Heat
Regenerated Sorbent
CO2-loaded Sorbent
E-CACHYS™
Fresh Sorbent
CACHYSTM Process Advantages
Advantages Low reaction heat ~ 40-80 kJ/mol
CO2 (novel chemistry and process conditions)
High sorbent capacity (> 7 g CO2/100 gm sorbent)
Increased sorption kinetics (smaller–sized equipment)
Use of low cost, abundantly available materials for sorbent
Use of commercially-demonstrated equipment design/configuration
Reduced capital and operating costs
8
020406080
100120140160180200
Heat
of r
eact
ion
(kJ/
mol
CO
2)
CACHYSTM Process Testing Objectives
9
• Confirmation of energetics
• Confirmation of sorbent capacity
• Confirmation of reaction kinetics
• Sorbent integrity
• Sorbent handling
Progress and Current Status
Technical Approach and Project Scope
Scope of work includes eight main tasks Task 1: Project Management and Planning
Task 2: Initial Technology and Economic Feasibility Study
Task 3: Determination of Hybrid Sorbent Performance Metrics
Task 4: Bench-Scale Process Design
Task 5: Bench-Scale Process Procurement and Construction
Task 6: Initial Operation of the Bench-Scale Unit
Task 7: Bench-Scale Process Testing
Task 8: Final Process Assessment
11
Significant Accomplishments
TGA/DSC Desorption Energy Data
0
20
40
60
80
100
120
140
A B C D
Des
orpt
ion
Ener
gy
(kJ/
mol
CO
2)
Hybrid Standard
13
• Desorption energy ~ 30-80 kJ/mol CO2 • Below target of 80kJ/mol CO2 and significantly lower
than standard carbonate process (130 kJ/mol CO2)
Fixed/Bubbling Bed Reactor: Multi-cycle Sorbent Testing
14
HCK-4 HCK-7
• Both sorbents exceeded goal of 7.0 g CO2/100g of sorbent and maintained capacity over the 100 cycle tests
Technical and Economic Feasibility Study
• Initial Technical and Economic Feasibility (550MWe) – Total O&M $28,290,000 – Capital Charge $102,504,000 – Total Cost $130,794,000 – CO2 Captured 3,614,000 Tons – Cost of CO2 Capture $36.19/ton – Cost of Electricity Increase 40%
15
16
Bench-Scale Facility
Sorbent manufacturing Sorbent drying system – rotary tube dryer
SEM Image – CO2 Loaded
17
SEM Image – Regenerated
18
19
Bench-Scale System Design – Block Flow Diagram
Separator 1(Fabric Filter 1)
Separator 2(SO2 Scrubber)
Reactor 1 (Circulating
Fluidized Bed)
Separator 3(Cyclone)
Separator 4(Fabric Filter 2)
Heat Exchanger 1(Solex Heater)
Reactor 2(Solex
Regenerator)
Heat Exchanger 2(Solex Cooler)
Separator 5(Particulate
Filter)
Separator 6 (Condenser)
30 acfm Flue Gas
<0.001 lb/hr Ash
Ash-FreeFlue Gas
5.2 lb/hr Fresh NaOH Solution
4.9 lb/hr Recirculated
Scrubbing Solution
Moist,Ash-and-SO2-Free
Flue Gas
RecirculatedSorbent
Sorbent Fines
CO2 Lean Flue Gas
0.2 lb/hr Purge Solution
220 lb/hrUtilized Sorbent
220 lb/hrRegenerated Sorbent
Sorbent Fines
Steam and CO2
Steam and CO2
13 lb/hr CO2
Steam and CO2
Condensate
Gas Conditioning
Adsorber
Regenerator
Regenerator Off-gas System
20
Bench-Scale Facility
Integration of bench-scale facility at UND’s steam plant
Control Room
Process Tower
Storage
Two 20 ft. shipping containers 30 ft. tall process tower fabricated by UND Flue gas sampled from either of two coal-fired boilers
21
Summary of Bench-scale Results to Date
• Parametric Testing: Short duration tests aimed at optimizing specific parameters
Tests to date have focused on operation of individual process components
Longer term, integrated tests are currently underway
• Adsorber: Demonstration of hybrid sorption benefits – large increases in capture and kinetics
Capture as high as 85% has been achieved to date
Working capacity of > 6 wt% (75% utilization after adsorption, 20% after regeneration)
Identified optimal process conditions and design basis
• Regenerator: Demonstration of hybrid sorption benefits – reduction of the regeneration energy
CO2 purity ~99%
Demonstrated positive impact of direct steam on desorption rate and energetics
Adsorber Testing – Data Summary
22
0
20
40
60
80
100
A B C D E F G H I
CO2 C
aptu
re %
Hybrid Sorption
Standard Sorption
A Zero Additive F Increased Fresh Feed B Sorbent Recirculation G Increased Gas Res. Time C Sorbent with Additive H Decreased Flue Gas CO2 D Sorbent Recirculation I Increased Gas Res. Time E Increased Additive Loading
23
Regenerator Testing
10
20
30
40
0
1
2
3
4
5
6
8:30 9:30 10:30 11:30 12:30 13:30
Sorbent Utilization, %
CO
2 Flo
w, l
b/hr
CO2 flow rateDesorbed CO2, lb/hrSorbent Utilization
Direct Steam On
Direct Steam Off
• Use of direct steam facilitates CO2 desorption
24
0
3
6
9
12
15
18
60
80
100
120
140
160
180
09:30 10:30 11:30 12:30 13:30 14:30
Regenerator Pressure (psig) Te
mpe
ratu
re (°
C)
Regenerator Indirect Steam Temp Regenerator - Sorbent Exit TempDirect Steam Temp Regenerator Pressure
Increasing Steam Flow
Steam Flow Stopped
• Use of direct steam increases sorbent temperature via exothermic reaction that reduces regeneration energy – confirms observations during lab-scale work
Regenerator Testing
25
Integrated Testing
• Achieved reasonable CO2 mass closures over an extended period
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
0
2
4
6
8
10
12
14
12:30 13:00 13:30 14:00 14:30 15:00 15:30 16:00 16:30 17:00
Closure, wt%
CO2 c
aptu
re/d
esor
ptio
n (lb
/hr)
CO2 Captured, lb/hrCO2 Desorbed, lb/hrCO2 Mass Closure, %
60
62
64
66
68
70
72
74
76
78
80
12:30 13:00 13:30 14:00 14:30 15:00 15:30 16:00 16:30 17:00Te
mpe
ratu
re (°
C)
FB1 1/4FB1 2/4FB1 3/4FB1 4/4
• Very good control of the exothermic heat of reaction in the adsorber
26
Operational Challenges/Mitigation Strategies
Challenges:
• Adsorber Capture efficiency
Reliable sorbent circulation
• Regenerator Condensation and flowability
Desorption rate
Mitigation Strategies: • Adsorber
Longer residence time/sorbent recirculation
Ensure sufficiently large surge volumes
• Regenerator Identification of stagnant zones Ensure heating of all contact surfaces Use of “soot blowers” and vibration Online cleaning Higher temperature operation
Scale up to larger diameter beds will alleviate many of the challenges experienced during bench scale operation
27
Remaining Work
• Complete Bench-scale Testing: Sorbent and process performance
Identify attrition rates and performance with SO2-containing flue gas
Adsorber and regenerator multi-cycle evaluation
Obtain data for scale-up and process economics
Determine environmental, health and safety (EH&S) concerns
• Final Process Assessment: EH&S
Final Technical and Economic Feasibility Study
28
Future Plans
• E-CACHYSTM
Developed as part of a DOE SBIR/STTR Phase I grant
Goal to increase sorbent capacity by 2x CACHYSTM sorbents
Capacity targets were achieved while maintaining other benefits of hybrid sorption
Phase II application was submitted to DOE - received notice of intent to award
• Phase II STTR Develop improved sorbent manufacturing methodologies
Modification of the existing bench-scale facility to accommodate improved sorbent
Demonstrate a new process configuration that greatly reduces the impact of sorbent attrition
Develop an improved hybrid sorption technology that will further reduce the cost of CO2 capture
Acknowledgements
Project Funding and Cost Share • U.S. Department of Energy (DOE-NETL) • Lignite Energy Council/NDIC • ALLETE (Minnesota Power and BNI Coal) • SaskPower • Solex Thermal • UND
DOE-NETL Project Manager – Andrew Jones
29
Contact Information Steven A. Benson
Institute for Energy Studies, University of North Dakota (701) 777-5177; Mobile: (701) 213-7070
Srivats Srinivasachar Envergex LLC
(508) 347-2933; Mobile: (508) 479-3784 [email protected]
Dan Laudal Institute for Energy Studies, University of North Dakota
(701) 777-3456; Mobile: (701) 330-3241 [email protected]
Harry Feilen Institute for Energy Studies, University of North Dakota
(701) 777-2730; Mobile: (701) 739-1199 [email protected]
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