32
High efficiency SCR system for most effective NOx reduction and best fuel economy for on- and off-road applications Dr. Ulrich Pfahl, Emitec Inc. Detroit, June 20 th , 2012
High efficiency SCR system for most effective NOx re ductionand best fuel economy for on- and off-road applicati ons
Dr. Ulrich Pfahl, Emitec Inc.Detroit, June 20 th, 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
PM
[mg/
kWh]
NOx [g/kWh]1
60
30
42 6
EU V EU IV
EU VI
03
Fue
l Con
sum
ptio
n
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
SLI
P
Hyd.
DOC
SCRS
LIP
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+NO 2
NOX Reduction
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400
Temperature [°C]
NO
x C
onve
rsio
n R
ate
[%]
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 temperatur e loss in the system
� Optimum hydrolysis of isocyanic acid – Preference for Hydrolysis Catalyst
� Good uniformity of NH3 – Optimized Mixing Tube Desig n
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
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60
Rel
ativ
e D
istr
ibut
ion
Den
sity
Droplet Size in Microns
0
20
40
60
80
100
0 10 20 30 40 50 60
Cum
ulat
ive
Mas
s %
Droplet Size in Microns
Droplet Mass Distribution
5 µm
70 µm
30 µm
< 5 mm
1110 mm
6100 mm
Evaporation distance requ. at 200 kg/h exhaust mass flow @ 430 °C Technical University Munich, tube-Ø 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 s teady state
0
100
200
300
400
500
600
0 200 400 600 800 1000 1200 1400 1600 1800
Tem
p. u
pstr
eam
SC
R C
at [°
C]
Time [s]
Oxi-Catalyst
UreaDosing
SCR
EU VI / US 2010 Engine
EU V Engine
Temperature Profile of a Commercial Vehicle with and wit houtElectrically Heated Catalyst (EHC): City Driving Cycle
150
175
200
225
250
275
300
0 250 500 750 1000 1250 1500 1750 2000
t [sec]
Tem
pera
ture
[°C
]
0
500
1000
1500
2000
2500
3000
Exh
aust
Mas
s F
low
[kg/
h]
Exhaust Temperature EHC Not Active
Ehxaust Temperature EHC Active
Exhaust 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 NO x-Reduction and NH 3 Slip as Function of NH3-Uniformity and DEF-Dosing Rate
0
10
20
30
40
50
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 poi nts
DEF Injector – Initial Layout
0102030405060708090
100
B50 A50 A25 B100 B25 C100 C25
NO
x E
ffici
ency
, %
ESC Load Point
DEF Injector – New Layout
0102030405060708090
100
B50 A50 A25 B100 B25 C100 C25
NO
x E
ffici
ency
, %
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
NO
x E
ffici
ency
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; NO 2/NOx = 0,27theoretical DEF demand for (alpha = 1) = 1100 ml / h
� setup with Fe-Zeolithe catalyst [Ø242 x (110 + 110)] ����10,1 ltr
� alpha = 0,87 – 1.04
NH3-distribution Example
Engine parameters With H-Cat Without H-Cat
NH3 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 Advantag e for NH3 formation
6th ICPC, Graz, 25. - 26.04.2011
Catalyst System – Validation of Mixing Pipe - Deposit s6th ICPC, Graz, 25. - 26.04.2011
Design w/o Hydrolysis-Cat
after 10 h Load point A 25
Design with Hydrolysis-Cat
after 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
40
50
60
70
80
90
100
200 250 300 350
Temperature [°C]
NO
x C
onve
rsio
n E
ffici
ency
[%]
200cpsi Standard
200/400cpsi LS
+ 4 %
+ 14%
200
cpsi
200/
400
LS
0
20
40
60
80
100
120
Std LS
WM
[%]
0
20
40
60
80
100
120
140
160
Std LS
ββ ββ [%
]
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; 30 0°C
LS/PE-Foil
79
88
0
10
20
30
40
50
60
70
80
90
100
Ceramic System Metallic System
NO
xC
onve
rsio
n E
ffici
ency
, %
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 i ncreased 20%
NO
xC
onve
rsio
n E
ffici
ency
, %
Comparison of Ceramic and Metallic Systems:NOx-Emission Reduction in ETC
7. FAD-Konferenz , November 2009
Euro VI Development
0
20
40
60
80
100
120
140
160
180
200
NH
3-S
lip, [
ppm
] (M
ax. V
alue
)
0
5
10
15
20
25
30
35
40
45
50
NH
3-S
lip, [
ppm
] (A
vera
ge V
alue
)
Maximum Value
Average Value
Ceramic-SCRWith NH 3-Slip
Catalyst
Metallic-SCRwithout NH 3-Slip
Catalyst
Metallic-SCRwithout NH 3-Slip
CatalystDEF incr. 20%
Metallic-SCRwith NH 3-Slip
CatalystDEF increased 20%
Comparison of Ceramic and Metallic Systems : NH 3 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 SLI
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/h
up to 1000 l/h
Capacity 7,5 l/h
Capacity 2 l/h
and 8 l/h
Capacity 2 l/h
and 8 l/h
Thank You
