simplification of diesel emission control system packaging
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14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008
Bukky
Oladipo, Owen Bailey, Ken Price, Noel Balzan
& Sumit
KaulAugust 5, 2008
Simplification of Diesel Emission Control System Packaging Using SCR Coated on DPF
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 2
Overview
Engine and Catalyst System
Two Development Phases:•
Phase 1 –
Does it work?
•
Phase 2 –
Major characteristics and determinant factors
Conclusions and Next Steps
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 3
Engine & Catalyst System
Steady State Tests•
6.6L Duramax; ′04 emissions•
NH3 or Urea injection
Catalyst System•
10.5”
x 12”
(17L)
•
SCR Washcoat
•
Optimized washcoat
SCR-filter
DOC
Aging•
Oven (hydrothermal)
•
50H @ 750 deg C
DOC SDPF
FTIREO_Bench TP_Bench
2 CLD Benches & 1 FTIR
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 4
SCR Filter Loading and Coating Process Optimized to Minimize Back-Pressure
Washcoat optimization helps minimize ΔP from SCR filterIncrease in ΔP becomes more pronounced above 1400 kg/hr of flow
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
600 800 1000 1200 1400 1600 1800 2000 2200
Air Mass Flow (kg/hr)
Pres
sure
Dro
p (k
Pa)
Standard CDPF
CDPF Reference
SCR Filters
Cold-Flow Test Results
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 5
Phase 1 Results: Oven-Aged (48H @ 650 deg C) SCR Filter
Up to 95% NOx Conversion Achieved
DOC SDPF
DOC•
7.5”
x 7”
(5.1L); Pt-only
•
Oven-Aged 16H @ 700°C, 10% H2O
SDPF•
10.5”
x 12”
(17L)
•
Oven-aged 48H @ 650°C, 10% H2O
•
SV = 23 to 52 kh-1
0
10
20
30
40
50
60
70
80
90
100
250 300 350 400 450 500 550
SCR Temp (deg C)
NO
x C
onve
rsio
n, N
O2/
NO
x (%
)
0
100
200
300
400
500
600
700
800
900
1000
NO
x C
onc
(ppm
)
NO2/NOx
NOx Eff, %
Inlet NOx
Test conducted with NH3 injection
(NH3 quantity increased until no change in tailpipe NOx)
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 6
Setup for SDPF Soot Burnout
7 degrees included angle diffuser
21”
33/8
”φ
12”
10.5”
6”
Inlet TCTC1 TC2 TC3
TC5TC4
Outlet TC
SDPF Test Procedure•
Active regeneration following each test
•
HC dosing targeting 700°C SDPF bed T
•
Burnout duration isapprox. 20 minutes
•
Exhaust Mass: 455 kg/hr; Space Velocity: 20.7 khr-1
0
100
200
300
400
500
600
700
800
900
1000
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Time (sec)
Tem
p (d
eg C
) / T
orqu
e (N
m)
0
300
600
900
1200
1500
1800
2100
2400
2700
3000
Spee
d (R
PM)
Mid Bed Temp Front Bed Rear Bed
Engine-out DOC Inlet Bed Torque (Nm)
Speed
Torque
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 7
NH3 vs Urea test results confirmed that urea decomposition is not a
limiting factor
Test Protocol for NH3 versus Urea Comparison
Back-to-back NH3 and Urea injectionMinimizes variation due to soot loading
Set Alpha = 1 for the NH3 Injection TestCatalyst purged with NOx before initiating urea
Avoids impact of pre-filling with NH3
Urea setting adjusted to match tailpipe NOx from NH3 test
DOC
SDPF
NH3 Injection Position 2
Urea
MixerNH3 Injection
To Tailpipe SDPF
DOC
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 8
Back-to-back NH3 versus Urea tests show same level of NOx performance
SCR Temperature = 250 °C
0
50
100
150
200
250
300
350
400
450
500
17500 18000 18500 19000 19500 20000
Con
cent
ratio
n (P
PM)
FTIR ahead of SCR (Behind NH3 injection) FTIR behind SCR
Ammonia Injection Period
~25% NO2
ηNOx
=63%
20500 21000 21500 22000 22500 23000 235000
5
10
15
20
25
30
35
40
45
50
Ure
a Si
gnal
TP Nox w/ Urea at Nox target from NH3
Similar Slip with Ammonia or Urea at same NOx Efficiency
Urea injection Period
ηNOx
=63%
Time (sec)
ENOX ppm TFTNH3 ppm TFTNO2 ppm
TFTNOX ppm TNOX ppm UREASP
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 9
Identical NOx Conversion supports matching of NH3 slip NH3 injection test to set identical
alpha ratio for the urea injection test
Hydrolysis and mixing not limiting factors
Aged: 50H @ 750 deg C hydrothermalAlpha = 1
0
10
20
30
40
50
60
70
80
90
100
150 200 250 300 350 400 450 500 550SDPF Bed Temp (degC)
NO
x Ef
ficie
ncy
(%)
0
25
50
75
100
125
150
175
200
225
250
NH
3 Sl
ip (p
pm)
NOx Eff - NH3 NOx eff - UREANH3 slip - NH3 NH3 slip - UREA
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 10
Phase 2 Test & Evaluation: Performance Xtics & Determinant Factors
SCR Filter Washcoat Optimization Effect of Soot Loading
Comparison to Equivalent Flow-Through SCR
Performance Over FTP and SET Cycles
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 11
Most important impact of washcoat optimization is on flow restriction,
not performanceAged: 50H @ 750 deg C hydrothermal
0
10
20
30
40
50
60
70
80
90
100
150 200 250 300 350 400 450 500 550
SDPF Bed Temp (degC)
NO
x Ef
ficie
ncy
(%)
0
60
120
180
240
300
360
420
480
540
600
NH
3 Sl
ip (p
pm)
Alpha = 1.0
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 12
Test at 250 °C; Soot level = 2.5g/l Higher soot load caused more
reduction in NOx conversion
0
10
20
30
40
50
60
70
80
90
100
0 2000 4000 6000 8000 10000 12000 14000
Time (s)
NO
x C
onve
rsio
n; N
O2/
NO
x (%
)
8
8.5
9
9.5
10
10.5
11
11.5
12
12.5
13
Bac
k Pr
essu
re (k
Pa)
NOx Eff %
ENO2/ENOx %Back Pressure
-12%NOx conversion
Back pressure
NO2 / NOx
4-Hour Steady State Test at SV = 21 khr-1; Alpha = 1
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 13
Comparison to Flow-Through Basis: Equivalency of total WC Mass
SCR Filter•
10.5”
x 12”
(17L)
Flow-Through•
Sized as appropriate to get equivalency
Oven-Aging:•
50H @ 750 deg C hydrothermal
Test Summary•
Both parts burnout at 700 °C to ensure•
No soot is present in SCR filter before test
•
Flow-through has same thermal history
•
Same DOC & Test Conditions(Inlet NOx; NO2/NOx; Space Velocity)
DOC SDPF
DOC SCR
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 14
SDPF versus Flow-Through (Alpha = 1)
0
10
20
30
40
50
60
70
80
90
100
150 200 250 300 350 400 450 500 550
SDPF Bed Temp (degC)
NO
x Ef
ficie
ncy
(%)
0
50
100
150
200
250
300
350
400
450
500
NH
3 Sl
ip (p
pm)
NOx Eff - SDPF NOx Eff - FlowThru
NH3 Slip - SDPF NH3 Slip - FlowThru
Comparison to Flow-Through SCR: Test Conducted with Urea Injection
•
Flow-through shows NOx conversion advantage over SDPF
•
Incorporation of flow-
through and SDPF may offer system configuration benefits
Oven-Aging: 50H @ 750 deg C hydrothermal
NH3Slip
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 15
NOx Performance Over Standardized Heavy-Duty Diesel Cycles
0
10
20
30
40
50
60
7080
90
100
NO
x C
onve
rsio
n (%
)
SET RMC(New SET)
FTP
Urea injection tests; Alpha = 1
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 16
Pressure Drop Across SDPF During Consecutive FTP’S
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
Pres
sure
Dro
p (k
Pa)
14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008 17
Conclusions and Next Steps
Results demonstrate possibility of high NOxperformance with SCR Filter
Using washcoat optimization, flow restriction was minimized without significant impact on NOxperformance
Under low temperature, some reduction in NOxconversion occurs with soot loading
DF characteristics is currently under study
Umicore’s advanced technology expected to further improve capability of the SCR filters
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