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High efficiency SCR system for most effective NOx reductionand best fuel economy for on- and off-road applications
Dr. Ulrich Pfahl, Emitec Inc.Detroit, June 20th, 2012
Agenda
Exhaust Emission Legislation & Strategies SCR System Layout & Development Requirements of Urea Dosing System Air Assisted / Airless Conclusion
Agenda
Exhaust Emission Legislation & Strategies SCR System Layout & Development Requirements of Urea Dosing System Air Assisted / Airless Conclusion
Exhaust Emission Legislations & Technologies Example : Commerical Vehicle - ETC
Engine Technology Euro VI
P
M
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m
g
/
k
W
h
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NOx [g/kWh]1
60
30
42 6
EU V EU IV
EU VI
0 3
F
u
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l
C
o
n
s
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m
p
t
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High Efficient SCR: > 95%
Engine Technology Euro IV
Agenda
Exhaust Emission Legislation & Strategies SCR System Layout & Development Requirements of Urea Dosing System Air Assisted / Airless Conclusion
SCR System Layout & Development
Euro IV : > 70% NOx efficiency
Euro V : > 85% NOx efficiency
Euro VI : > 95% NOx efficiency DPF/SCR
S
L
I
P
Hyd.
DOC
SCRS
L
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DOC
SCR SilencerSilencer
SilencerSilencer
SilencerSilencer
SCR Processes
{(NH2)2CO 7H2O}fl {(NH2)2CO}fl + 7 H2O water evaporation
{(NH2)2CO}fl HNCO + NH3 thermolysis of urea
HNCO + H2O CO2 + NH3 hydrolysis of isocyanic acid
NH3 Formation
4 NO + O2 + 4 NH3 4 N2 + 6 H2O standard reaction with NO
2 NO2 + 2 NO + 4 NH3 4 N2 + 6 H2O fast reaction with NO+NO2
NOX Reduction
0102030405060708090
100
0 100 200 300 400
Temperature [C]
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NO2 / NO50%
NO2 / NO0%
SCR Processes
{(NH2)2CO 7H2O}fl {(NH2)2CO}fl + 7 H2O water evaporation
{(NH2)2CO}fl HNCO + NH3 thermolysis of urea
HNCO + H2O CO2 + NH3 hydrolysis of isocyanic acid
NH3 Formation
Develop System according to Critical SCR Processes : Good evaporation of DEF optimized amount of DEF injected per time per unit
targeted area , in order to minimize the temperature loss in the system Optimum hydrolysis of isocyanic acid Preference for Hydrolysis Catalyst Good uniformity of NH3 Optimized Mixing Tube Design
Adblue Droplet Hitting the Target Surface Evaporation
Agenda
Exhaust Emission Legislation & Strategies SCR System Layout & Development Requirements of Urea Dosing System Air Assisted / Airless Conclusion
Key Considerations of Urea Dosing System Design
Air Assisted / Airless Mass Per Droplet Size
Air assisted SCR System: Measured Droplet Size - and Droplet Mass Distribution at 20 l/min Airflow
Droplet Size Distribution
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0.2
0.4
0.6
0.8
1
1.2
0 20 40 60
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Droplet Size in Microns0
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0 10 20 30 40 50 60
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Droplet Size in Microns
Droplet Mass Distribution
5 m
70 m
30 m
< 5 mm
1110 mm
6100 mm
Evaporation distance requ. at 200 kg/h exhaust mass flow @ 430 C Technical University Munich, tube- 55 mm
Key Considerations of Urea Dosing System Design
Air Assisted / Airless Mass Per Droplet Size
Temperature Layout Exhaust Gas Temperature ( injector
location, insulation), Injection Strategy
New Conditions for HD Truck Catalyst Systems;Exhaust Gas Temp. EU V / US 2010 (EU VI); 13mode steady state
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0 200 400 600 800 1000 1200 1400 1600 1800
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Time [s]
Oxi-Catalyst
UreaDosing
SCR
EU VI / US 2010 Engine
EU V Engine
Temperature Profile of a Commercial Vehicle with and withoutElectrically Heated Catalyst (EHC): City Driving Cycle
150
175
200
225
250
275
300
0 250 500 750 1000 1250 1500 1750 2000t [sec]
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Exhaust Temperature EHC Not ActiveEhxaust Temperature EHC ActiveExhaust Mass Flow
Benefit in Temperature with
EHC
Key Considerations of Urea Dosing System Design
Air Assisted / Airless Mass Per Droplet Size
Temperature Layout Exhaust Gas Temperature ( injector
location, insulation), Injection Strategy Mixing Pipe Design - Tasks
Avoid Deposit formation Good Uniformity Creation of NH3
Calculated NOx-Reduction and NH3 Slip as Function of NH3-Uniformity and DEF-Dosing Rate
0
10
20
30
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60
0.88 0.9 0.92 0.94 0.96 0.98 170
75
80
85
90
95
100
0.88 0.9 0.92 0.94 0.96 0.98 1
NH3- Slip [ppm]
NH3-Uniformity
NOx-Reduction [%]
NH3-Uniformity
Alpha = 1.00
NOx Reduction @ selected US EPA 13mode / ESC load points
DEF Injector Initial Layout
0102030405060708090
100
B50 A50 A25 B100 B25 C100 C25
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f
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%
ESC Load Point
DEF Injector New Layout
0102030405060708090
100
B50 A50 A25 B100 B25 C100 C25
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f
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%
ESC Load Point
High Load Points
NOx Efficiency with Optimized Airless Dosing Layout & StrategySummary of Sweep Test
86
88
90
92
94
96
98
100
0.85 0.9 0.95 1 1.05
N
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Alpha (-)
Test conditions: constant speed / torque
constant temperature and massflow and exhaust gas condition
exhaust gas 714 kg/h, T = 420 C, NO x = 543 ppm; NO2/NOx = 0,27theoretical DEF demand for (alpha = 1) = 1100 ml / h
setup with Fe-Zeolithe catalyst [242 x (110 + 110)] 10,1 ltr
alpha = 0,87 1.04
NH3-distribution Example
Engine parameters With H-Cat Without H-CatNH3 HNCO NH3 HNCO
A 25 Load Point:Exh Gas Temp: 310 CExh Gas Massf.: 850 kg/h
54,7 32,5 17,3 17,9
Average Concentration
Hydrolysis Cat ( H-Cat) gives significant Advantage for NH3 formation
6th ICPC, Graz, 25. - 26.04.2011
Catalyst System Validation of Mixing Pipe - Deposits6th ICPC, Graz, 25. - 26.04.2011
Design w/o Hydrolysis-Catafter 10 h Load point A 25
Design with Hydrolysis-Catafter 10 h Load point A 25
Hydr.-Cat outletHydr.-Cat Inlet
Liebherr SCR Production System
watercooledinjector
hydrolysiscatalyst
SCR catalyst
LS Technology
6th ICPC, Graz, 25. - 26.04.2011
Key Considerations of Urea Dosing System Design
Air Assisted / Airless Mass Per Droplet Size
Temperature Layout Exhaust Gas Temperature ( injector
location, insulation), Injection Strategy Mixing Pipe Design - Tasks
Avoid Deposit formation Good Uniformity Creation of NH3
SCR Catalyst Structure Conversion Efficiency Ammonia Slip
Influence of Cell Structure on NOx Conversion Efficiency
0
10
20
30
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50
60
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80
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200 250 300 350
Temperature [C]
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v
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f
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[
%
]
200cpsi Standard200/400cpsi LS
+ 4 %
+ 14%
2
0
0
c
p
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2
0
0
/
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0
L
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20
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60
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100
120
Std LS
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M
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%
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0
20
40
60
80
100
120
140
160
Std LS
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%
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Washcoat Mass Transfer
100
80
60
40
0
20
ConcentrationTracer gas [%]
Position A Position H
18 [mm]
Flow
Radial Mixing after a substrate length of 18 mm LSPETracer Gas injected into a single Channel; 200kg/h; 300C
LS/PE-Foil
79
88
0
10
20
30
40
50
60
70
80
90
100
Ceramic System Metallic System
N
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%
Comparison of Ceramic and Metallic Systems:NOx-Emission Reduction in ETC
7. FAD-Konferenz , November 2009
79
88
97
0
10
20
30
40
50
60
70
80
90
100
Ceramic System Metallic System Metallic System, DEF increased 20%
N
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%
Comparison of Ceramic and Metallic Systems:NOx-Emission Reduction in ETC
7. FAD-Konferenz , November 2009
Euro VI Development
020
40
60
80
100
120
140
160
180
200
N
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0
5
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(
A
v
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)Maximum ValueAverage Value
Ceramic-SCRWith NH3-Slip
Catalyst
Metallic-SCRwithout NH3-Slip
Catalyst
Metallic-SCRwithout NH3-Slip
CatalystDEF incr. 20%
Metallic-SCRwith NH3-Slip
CatalystDEF increased 20%
Comparison of Ceramic and Metallic Systems : NH3 Slip in ETC7. FAD-Konferenz , November 2009
Agenda
Exhaust Emission Legislation & Strategies SCR System Layout & Development Requirements of Urea Dosing System Air Assisted / Airless Conclusion
High Efficient SCR System Development
LS
LS/PE
LS
SCR
S
L
I
P
EHCHydr. Silencer
DOC
LS
Emicat
Mixer
PM Metalit
SilencerSilencer
Vertraulich / ConfidentialCopying of this document and giving it to others is strictly forbidden without express authority of Emitec!
Airless Urea Injection
Emitec NoNOx SCR Platforms
Airless Urea Injection
Digital Dosing Pump Urea Injection
Air-Assisted Urea Injection
Capacity 60 l/hup to 1000 l/h
Capacity 7,5 l/h
Capacity 2 l/hand 8 l/h
Capacity 2 l/hand 8 l/h
Thank You