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