development of scr on diesel particulate filter system for heavy
TRANSCRIPT
10/17/2012
Development of SCR on Diesel Particulate Filter System for Heavy Duty Applications
Mojghan Naseri, Daniel Kucheruck, Hai-Ying Chen , Sougato Chatterjee
DEER Conference 2012
Outlines
Introduction
Objectives
Experimental
Results NOx Conversion Backpressure Passive Regeneration
Summary
Introduction
Most 2010 heavy duty systems include: DOC + CSF + SCRs + ASC NOx reduction with emission control has been introduced
With proposed future regulations for GHG control and more emphasis on improved fuel economy, future engines will be designed with higher engine out NOx
Therefore, these future engines will require emission control systems with much higher NOx conversion capability
Additional NOx control across the DPF is being considered as one means of improving overall system NOx reduction capability
Objectives
Evaluate SCR coated DPFs in US 2010 configuration to understand NOx conversion capabilities of such systems
Test under Steady state Test under Transient cycles
Determine how SCR-DPF system can support higher NOx reduction for higher engine out NOx
Evaluate how filter regeneration is affected by introducing SCR coating on the DPF
Experimental - Systems for Testing
SCR-DPF System
Urea Injection
Engine out Exhaust
DOC)SCR-DPF
Urea Injection
Engine out Exhaust
DOC)SCR-DPF SCR
Urea Injection
Engine out Exhaust
DOC)SCR-DPF SCR
SCR-DPF + SCR System
SCR-DPF + 2 SCR System
Experimental Procedure
• Engine: 6 Cylinder US 07 engine • EGR off, NOx= 4-5 g
• Units: DOC: Degreened, aged at 700ºC for 100hrs with 10% water
SCR-DPF/SCR: Aged at 650ºC for 100hrs with 10% water • Steady State:
• Temp from 200°C to 440°C, ANR=1.2
• FTP Runs • Cold FTP • Hot FTP • ANR ~ 1.3
NOx Conversion
SCR-DPF Provides Significant NOx Conversion Advantages Equivalent system volume
0
10
20
30
40
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60
70
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90
100
Cold Warm Hot 1 Hot 2 Hot 3
NO
x C
onve
rsio
n %
CSF-(EGR Off)
SCR-DPF-Two SCR (EGR Off)
SCR-DPF + 2 SCR system
SCR-DPF Provides NOx Conversion Advantages at Low temperature Equivalent system volume, ANR=1.2
0
10
20
30
40
50
60
70
80
90
100
180 200 220 240 260 280 300 320 340 360 380 400 420 440 460
NO
x C
onve
rsio
n %
SCR/SCRF Inlet Temperature (C)
CSF System
SCR-DPF System-Two SCRs
SCR-DPF + 2 SCR system
SCR-DPF Optimization Optimization include; high NO2, improved SCR-DPF coating, improved SCR formulation
Urea Injection
Engine out Exhaust
DOC)SCR-DPF SCR
Urea Injection
Engine out Exhaust
DOC)SCR-DPF SCR
SCR-DPF + SCR System
SCR-DPF + 2 SCR system
0
10
20
30
40
50
60
70
80
90
100
Cold FTP Hot FTP
NO
x C
onve
rsio
n %
CSF SystemSCR-DPF-Two SCR SystemSCR-DPF+SCR System
SCR-DPF Optimization Optimization include; high NO2, improved SCR-DPF coating, improved SCR formulation
Urea Injection
Engine out Exhaust
DOC)SCR-DPF SCR
Urea Injection
Engine out Exhaust
DOC)SCR-DPF SCR
SCR-DPF + SCR System
SCR-DPF + 2 SCR system
0
10
20
30
40
50
60
70
80
90
100
Cold FTP Hot FTP
NO
x C
onve
rsio
n %
CSF SystemSCR-DPF-Two SCR SystemSCR-DPF+SCR System
Optimized SCR-DPF system can provide high NOx conversion even with single SCR substrate
Backpressure
SCR-DPF Backpressure Improvement Optimized coating helped to reduce backpressure while maintaining NOx conversion
0
10
20
30
40
50
60
70
80
90
100
0
1
2
3
4
5
6
7
8
9
10
SCR-DPF-B SCR-DPF-A
NO
x C
onve
rsio
n %
Bac
kpre
ssur
e ("
Hg)
Max BP "Hg/Warm FTPMax BP "Hg/Hot FTPNOx Conv
Passive Regeneration
Test Protocol
SCR-DPF loaded up to 3g/l of soot
Speed A and DOC inlet temperature 400°C was chosen to evaluate passive regeneration. Filters were regenerated for 30 min.
Passive Regeneration during FTP cycle with urea injection (30hrs).
Following regeneration, filters were weighed while still hot at around 180°C
SCR-DPF was regenerated with EGR off
SCR-DPF passive regeneration capability was studied with urea injection (ANR=1.0)
Test Condition During Steady State
Engine Out NOx (g/hp-hr) 5.5-5.8
NO2/NOx (%) DOC Out (Aged DOC)
400ºC=33-35%
NO2/NOx (%) DOC Out (Degreened DOC)
400ºC=45%
DOC SV (1/hr) 105,000
DPF SV (1/hr) 35,000
Combination of SCR-DPF Design and NO2/NOx Optimization Allows for Good Passive Regeneration with SCR-DPF SCR-DPF (EGR Off)-30min Regeneration-Urea dosing ANR=1.0
0
5
10
15
20
25
30
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
SCR-DPF A-Low NO2 SCR-DPF D-Low NO2 SCR-DPF A-High NO2 SCR-DPF D-High NO2
Soo
t Bur
n %
Soo
t Loa
d (g
/l)
Soot load (g/l)
Soot load after Regen (g/l)
Soot burn
Low NO2 High NO2
Combination of SCR-DPF Design and NO2/NOx Optimization Allows for Good Passive Regeneration with SCR-DPF SCR-DPF (EGR Off)-30min Regeneration-Urea dosing ANR=1.0
0
5
10
15
20
25
30
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
SCR-DPF A-Low NO2 SCR-DPF D-Low NO2 SCR-DPF A-High NO2 SCR-DPF D-High NO2
Soo
t Bur
n %
Soo
t Loa
d (g
/l)
Soot load (g/l)
Soot load after Regen (g/l)
Soot burn
Low NO2 High NO2
Promising Passive Regeneration was achieved
Test Protocol
SCR-DPF loaded up to 3g/l of soot
Speed A and DOC inlet temperature 400°C was chosen to evaluate passive regeneration. Filters were regenerated for 30 min.
Passive Regeneration during continuous FTP cycles with urea injection (30hrs).
Following regeneration, filters were weighed while still hot at around 180°C
SCR-DPF was regenerated with EGR off
SCR-DPF passive regeneration capability was studied with urea injection (ANR=1.3)
SCR-DPF Design Allows for Good Passive Regen under Transient Test Condition 30 hrs of FTP cycle, with urea injection, ANR~1.3, no urea injection during Soot loading, NO2/NOx ~40%
0
1
2
3
4
5
6
7
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9
10
0 10 20 30 40 50 60 70 80 90 100
Bac
kpre
ssur
e ("
Hg)
FTP Cycle
CSF
SCR-DPF B
SCR-DPF D
SCR-DPF Design Allows for Good Passive Regen under Transient Test Condition 30 hrs of FTP cycle, with urea injection, ANR~1.3, no urea injection during Soot loading, NO2/NOx ~40%
0
1
2
3
4
5
6
7
8
9
10
0 10 20 30 40 50 60 70 80 90 100
Bac
kpre
ssur
e ("
Hg)
FTP Cycle
CSF
SCR-DPF B
SCR-DPF D
Optimized SCR-DPF has similar passive regeneration as CSF
Summary
SCR coated DPF systems are being designed to provide improved NOx reduction in future emission control systems
Transient results indicate that optimized SCR-DPF system provides high NOx conversion using same or smaller package volume as compared to 2010 system
SCR-DPF shows promising passive regeneration with higher engine out NOx during steady state
Passive regeneration was achieved during transient cycle under the conditions chosen for this study
These results suggest that SCR coated DPF can significantly help in meeting emissions with future higher NOx engines and thus assist in meeting higher fuel economy targets