Post on 21-Dec-2016
Diesel Particulate Filter Technology for Low-Temperature and Low-NOx/PM
ApplicationsDEER Conference, 2004
Sougato Chatterjee, Ray Conway, Satish Viswanathan, Todd Jacobs
Johnson Matthey CatalystsEnvironmental Catalysts & Technologies
Outline
• Introduction• CRT Filter System
– Operational fundamentals– Application issues
• Active Regeneration Technologies for DPF– Low Temperature– Low NOx/PM
• Advanced CRT with Passive Regeneration – Low Temperature– Low NOx/PM
• Conclusions
Diesel Particulate Filter
• Johnson Matthey Continuously Regenerating Technology (CRT®) Diesel Particulate Filter
InletHead
CatalystSection
Filter Section
OutletHead
OxidationCatalyst
Wall-flowFilter
CRT System – Operating Principle
CRT System - Operational Guidelines
• CRT system operating requirements– Exhaust temp > 260°C for 40% of the
operating time– Engine out NOx/PM ratio to be > 25.
0
10
20
30
40
50
60
200 300 400 500 600Temperature (°C)
NO
x/PM
ratio
Temperaturelimit
chemical limit
Operating Area
CRT System - Application Issues
• Low operating temperature– In retrofit, low
exhaust temperature can restrict the applications of CRT
– viz. Large engines with low hp – MACK E7 300 hp, CAT 3126 175 hp
CRT System - Application Issues
• Engine out low NOx/PM ratio emissions
– 2.5 g/bhp-hr NOx engines can have NOx/PM ratios that are < 20
– Older engines
Possible Solutions
• Active regeneration of DPF system – Actively increase engine out exhaust temperature
to allow NO2 based regeneration– Actively increase temperature to combust soot
with O2
• Enhanced passive regeneration of DPF system– Catalytically promote combustion of soot with NO2
at lower temperatures– Promote the reuse NO/NO2 to combust soot in the
DPF
Active Regeneration of Filter System
Potential Active Regeneration Strategies
• (a) Moderate Temperature Regeneration (300-350oC) with NO2
• Air Restriction• Fuel Injection• Takes relatively long time (lower soot burn rate)• More frequent on-set or longer operation• Safe strategy
• (b) High Temperature Regeneration (550-600oC) with O2
• Fuel injection• Burner• Rapid regeneration • Less frequent on-set• Potential risk of filter damage from exotherm
Active Regeneration: Cold Temperature Applications
Active Regeneration Methods Using Air Restriction
Wastegate
Compressor
Intercooler
Turbine
Air Filter
Pre-Turbo Throttle Exhaust brake
VGT
Intake Throttle
CRT
Method SelectedMethod Selected
Increase in Turbo Out Exhaust Temperature with Intake Throttle FTP Testing on MACK E7 Engine
50
75
100
125
150
175
200
225
250
275
300
325
350
375
400
425
450
475
0 200 400 600 800 1000 1200
Cycle Time (Sec)
Exha
ust t
emp
(C)
No ThrottleMack MaxIdle Only Throttle Mack Max with Clamping
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
100 125 150 175 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 375 400 425 450 475 500Temp (C)
Tim
e O
ver t
emp
(%)
No Restriction
Max RestrictionMax Restriction with Clamping
Idle Only Restriction
Effect of Intake Throttle on Engine Emissions FTP Testing on MACK E7 Engine
Final FTP Results with ThrottleMACK E7 Engine
0
1
2
3
4
5
6
7
Emis
sion
s (g
/bhp
-hr)
No Restricition 4.265 0.107 0.903 5.61 5.86Max Restriction 4.39 0.131 1.82 5.83 5.78Max w/ Clamp 4.37 0.119 1.78 5.79 5.77
NOx PM Fuel (/100) CO CO2 (/100) Power (x10 bhp)
NOx/PM RatiosNo Restrict = 40Max Restrict = 34Max w/ Clamp = 37
Active Regeneration of CRT with IntakeThrottle System
• Mack trash truck with Heil body
– 2000 MY
– Engine E7
– 12 liter in-line 6 cylinder rated at 300 hp at 1950 rpm
Intake Throttle Valve
Throttle System Performance – Significant Increase in Temp Profile
NYDOS Truck (Mack Powered) Effect of Throttle
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
100 125 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 325 350 375 400Temp bins
Tim
e O
ver t
emp
BASELINE
With Trottle Only
With Throttle and CRT
Throttle System Performance – Stable Peak Backpressure with CRT
Active Regeneration: Low NOx/PM applications
Active Regeneration with Fuel Injection
Catalyst and DPF
Fuel supply
Engine information
and actuation
Injection system assembly Control system
Exhaust information
Air supply
System information and actuation
Courtesy:
•Soot combustion with O2
•Filter temp > 600 C
•Typical 400 – 600 sec. regeneration cycle
•Fuel injection optimized to avoid HC slip 0
100200300400500600700800
680 760 840 920 1000 1080 1160 1240
Time (sec)
Tem
pera
ture
(°C)
00.030.060.090.120.150.180.210.24
Pres
sure
Dro
p (b
ar)
T_DPF_InletP_DPFT_DPF_OutletT_DPF InletT_DPF OutletP_DPF
200
250
300
350
400
450
500
550
600
650
0 200 400 600 800 1000 1200Time (sec)
Tem
pera
ture
(°C
)
0.000
0.020
0.040
0.060
0.080
0.100
0.120
pres
sure
dro
p (B
ar)
Temp bef catalyst
Temp bef filter
dP filter CRT
dP filter CCRT
Active Regeneration of CRT Using Fuel Injection
Engine speed
Engine load
Temperatures
Air/fuel actuator
Flush actuator
Fuel pressure
Air pressure (x3)After catalyst
At DPF
Exhaust pipe
Before catalyst
600 °C
500 °C
350 °C
Courtesy:
Active Regeneration of CRT with Fuel Injection System
Exhaust back pressure
Temperatures
After catalystBefore catalyst
3 hours
140 mbar
Courtesy:
Active Regeneration of CRT with Fuel Injection System
CCRT™ Filter System with Passive Regeneration
CCRT™ – An Advanced CRT for Challenging Applications
• CCRT = DOC + Catalyzed Filter • Advantages of CCRT:
– Higher soot burn rate than CRT or CSF• Install in Challenging Applications
– Low temperature applications (200 – 250oC)– Low NOx/PM applications (NOx/PM>15)
• Even at low CSF loadings, we see improved performance with the CCRT
• Successfully demonstrated in field trials in the US, Europe and Asia
CCRT System – Operating Principle
CRT Versus CCRT Stabilization Comparison FTP Cycle, NOx/PM = 14
Soot Burn Rate Comparison for CRT and CCRT Transient Cycle Testing, NOx/PM = 15
Engine Out Soot = 20 g/h
05
10152025303540
200 220 240 260 280 300 320 340
Exhaust Temp (°C)
Soot
Bur
n R
ate
(g/h
)
Cat + DPFCat + CSF
CCRT Field Operation: Cold Temperature Applications
CCRT Experience on Low-Temperature School BusBoston School Bus with 175-hp 2000 MY CAT 3126 Engine
Daily Pressures on
-1
0
1
2
3
4
5
6
12/3
0
1/30
2/28
3/30
4/30
5/30
6/30
7/30
8/30
9/30
10/3
0
11/3
0
12/3
0
1/30
2/29
3/30
4/30
Date
BacK
Pre
ssur
e (in
Hg)
Max Pres Avg Max Pres Avg Pres
ToBoston School Bus 006
30-Dec-02 14-May-04
Temperature Distribution
0
250
500
750
1000
1250
1500
1750
2000
2250
2500
100
125
150
175
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
Exhaust Bins (C)
Freq
uenc
y (A
bsol
ute)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Tim
e ov
er te
mp
(%)
Frequency%Time Above Temp
ToBoston School Bus 006
30-Dec-02 14-May-04
•Cold Exhaust Temperature Profile
•Only 8% of time Temp > 260 C; 40% time @ 200 C
•CCRT operating with stable back pressure for over 17 months
•Cold Exhaust Temperature Profile
•13% of time Temp > 260 C
•CCRT operating with very stable back pressure since Jan 2003
0
900
1800
2700
3600
4500
5400
6300
7200
8100
9000
0 100 125 150 175 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 375 400 425 450 475 500
Temperature (C)
Freq
uenc
y (a
bsol
ute)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Tim
e at
Tem
p (%
)
CCRT Experience on Low-Temperature Delivery TruckYosemite Water Truck with 190-hp Intl DT466 Engine, FT Fuel
Chassis Dyno Emission Results2001 International DT466 190hp, CCRT with FT fuel
* below detection limit
Vehicle Number
201 202 203 204 205 206 204 205 206
/ 0.0
0.5
1.0
1.5
2.0
2.5
CO NOx/10NO/10HC PM
CSHVR Drive Cycle
CARB Fueled Vehicles,No Filter
FT Fueled Vehicles,No Filter
FT Fueled Vehicles,With CCRT Filter
** * * * * **
Vehicle Number
201 202 203 204 205 206 204 205 206
Ei
i/
i
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
CO/10NOx/100NO/100HCPM
CARB Fueled Vehicles,No Filter
FT Fueled Vehicles,No Filter
FT Fueled Vehicles,With CCRT Filter
* * * * * *
NYCB Cycle
* below detection limit
Emission Reductions CSHVR:
CO: 99.5%
HC: 100%
PM: 99.4%
Emission Reductions NYCB:
CO: 100%
HC: 100%
PM: 96%
CCRT Installed on NY City Trash Trucks with Mack E 7 Engine – Very Cold Operating Temp.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
100 125 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 325 350 375 400 425 450Exhaust Temp (°C)
Tim
e A
bove
Tem
p (%
)
CW 026 (CCRT) 12/26/03 to 8/5/04CW 316 (CCRT) 12/26/03 to 8/5/04
•Very cold Exhaust Temperature Profile
•8 - 10% of time, Temp > 260 C
Stable Operation of CCRT on NY City Trash Truck with MACK E7 Engine
CCRT Field Operation: Low NOx/PM Applications
•Exhaust Temperature 40% of time Temp > 320 C
•NOx/PM suspected << 20
•CCRT operating with very stable back pressure
CCRT Benefit over CRT on Low-NOx/PM Engine8-L Engine 10.5 x 12 CCRT
• Under FTP NOx/PM = 30
• Under some operating conditions NOx/PM dropsto < 10.
• CRT would plug with soot in months
• CCRT operating successfully for over 12 months.
CCRT Benefit over CRT on Old, High-PM EngineCalifornia School Bus with 2-Stroke Engine
Conclusions
• Low temperature and low NOx/PM ratio engine - challenging applications for DPF installation
• However, advanced DPF systems utilizing active and passive regeneration strategies can be successfully used in challenging applications
• Successful active regeneration systems include air restriction and fuel injection methods
• But, complexities with active regeneration systems; Fuel penalty, higher cost
• CCRT with advanced passive regeneration strategy has been demonstrated to be successful in such challenging applications
• CCRT can work:– T 40% @ 200 – 210 C– NOx/PM > 15
Acknowledgments
• STT Emtec• Caterpillar Inc.• Volvo/Mack• NY DOS• Environment Canada
Contacts
• Marty LassenLassem@JMUSA.com
• Doug EmigEmigd@JMUSA.com
• Sougato ChatterjeeChatterjee@JMUSA.com
• WWW.JMCSD.COM
• Johnson Matthey CatalystsDiesel Emission Control Systems380 Lapp RoadMalvern, PA 19355(800)RX-FOR-AIR