simplification of diesel emission control system packaging

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


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


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


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)


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


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


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


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


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


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


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


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


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


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


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)


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

14th Diesel Engine-Efficiency and Emissions Research (DEER) Conference , Aug. 4 – 7, 2008

Thank You for Your Attention

simplification of diesel emission control system packaging

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