comparison of ammonia continuous measurement techniques ...€¦ · practical requirements by...

Comparison of Ammonia Continuous Measurement Techniques from an SCR Vehicle

Eighth CLEERS WorkshopMay 19, 2005

Hajime Ishii, Hisakazu SuzukiEnvironment Research Department

National Traffic Safety and Environment Laboratory, JAPAN

Presentation overview

1. Background (Emission regulation)2. Feasibility study of SCR vehicles

3. Ammonia measurement test

4. Activated and de-activated catalyst test

5. Conclusion

History of emission regulation

0.00

0.05

0.10

0.15

0.20

0.0 1.0 2.0 3.0

NOx (g/kwh)

PM (g

/kw

h)

US 2010

JPN 2004

JPN 2005

US 2004(NMHC+NOx)

EURO5(ETC)2008

EURO4(ETC)2005

JPN 2009

(0.7,0.01)

Challenge target values

(0.23,0.01)

What is What is ““Challenge Target ValuesChallenge Target Values”” for HD vehicles?for HD vehicles?

• Higher target values have been established with the expectation of further technological progress.

(Subject) • Developments of NOx reduction performance at low-temp.• Future prospect of practical utility of HCCI or new technology.• ……e.t.c.

• After verifications have been made around 2008, final decision will be made on the necessity of new target values and the achievement year.

（Reference: Kubota H., JSAE 2005 Spring Meeting)





5. Conclusion

Test vehicles with SCR system

VehicleA

Vehicle DVehicle C

VehicleB

1999 Reguration + SCR system (no engine adjustment)

（Reference: JARI, “Research Development of Exhaust Gas Aftertreatment System, 2003）

Specification of The Urea SCR System

A B C D

5.1L － 8.5L 8.5L

Vanadium46.4L

Vanadium30.2L

Vanadium53.4L

Zeolite17.0L

－－ 7.0L 8.5L

Resin50L

Resin50L

Resin50L

Stainless steel15L

Urea water tank

System / VehicleNO oxidation catalystVolumeSCR catalystVolumeNH3 slip catalystVolume

SAE 2004-01-1944

optional element

Engine

Dosingcontrol

unit

NOoxidationcatalyst

SCRcatalyst

Exhaust

・NO→NO2

・CO,HC reduction･NOx reduction ・NH3 reduction

UreawaterUrea water

tank

NH3slip

catalyst

Urea→NH3

Dosing nozzle

Exhausttemperaturesensor

ECU

optional element

Engine

Dosingcontrol

unit

NOoxidationcatalyst

SCRcatalyst

Exhaust

・NO→NO2

・CO,HC reduction･NOx reduction ・NH3 reduction

UreawaterUrea water

tank

NH3slip

catalyst

Urea→NH3

Dosing nozzle

Exhausttemperaturesensor

ECU

D13 Emissions Performance

CO HC NOx PM CO2

System A Base 1.46 0.31 4.65 0.17 847w/SCR 0.03 0.01 1.76 0.17 844Conversion 98.1 95.8 62.1 -2.9 0.4

System B Base 1.07 0.42 4.29 0.21 783w/SCR 1.69 0.06 1.28 0.22 788Conversion -56.9 86.7 70.2 -7.2 -0.7

System C Base 1.18 0.30 5.34 0.03 781w/SCR 0.20 0.05 1.87 0.02 801Conversion 82.7 82.4 65.1 29.4 -2.5

System D Base 0.98 0.14 4.87 0.20 827w/SCR 0.00 0.01 2.11 0.23 839Conversion 99.9 94.3 56.7 -16.7 -1.5

Emission (g/kWh)

SAE 2004-01-1944

NOx Conversion Ratio and NH3 Slip

0

20

40

60

80

100

15.2 27.4 44.8 74.7Average vehicle speed km/h

NO

x co

nver

sion

ratio

%

System A System BSystem C System DSystemA' SystemD'

0

10

20

30

40

50

60

15.2 27.4 44.8 74.7

Average vehicle speed km/hN

H3

(ave

rage

) p

pm

SAE 2004-01-1944

Systems A’ and D’ : After adjustment of urea injection in transient test 2 and 4

JE05

Conclusion-1 of the feasibility study

• The maximum NOx conversion ratio of the urea SCR system developed was 70% under the steady-state test of D13 mode cycle, but decreased during the transient driving cycle. This must be significantly improved in order to apply for future emission regulation, especially under low-speed operating conditions.

• NH3 slip under the D13 and the transient cycle was eliminated by adjusting the urea injection, but the trade off between NOx conversion efficiency and NH3 slip has to be improved in order to put the urea SCR system to practical use.

SAE 2004-01-1944





5. Conclusion

Necessity of NH3 measurement

・to a human -TWA (Time Weighted Average) defined by ACGIH (American Conference of Governmental Industrial Hygienists) is 25ppm, which is the same as CO

・from a vehicle-NH3 formation reaction is taken place on catalyst, when NOx is reduced in rich condition-NH3 slips when urea solution is injected to much in urea SCR system

NH

H H

We need to understand accurate measurement method of NH3

Ammonia

・readily soluble in water

→ large error caused by water vapor condensation in exhaust gas

・reaction to other components in exhaust gas

→ easily stagnant in a sample line

Object: Quantification of temporal and total NH3 emission under transient condition

Characteristics of NH3

Therefore, it is difficult to measure NH3 by CVS system.

To fulfill above object, heated direct line sampling is necessary in measurement test.

NH3 measurement of SCR vehicle

NH3 measurement of SCR vehicle

Comparing and evaluating four continuous NH3 measurement systems

Understanding accuracy and characteristics of practical requirements by measuring heavy duty truck equipped with urea SCR system

Dual Chemiluminescence detector

（Dual CLD=DCLD）-Two CLD detectors-One has a converter which converts NH3 to NOx- (NH3+NOx)-(only NOx) =NH3

Advantage: reliability of NOxmeasurementDisadvantage：affected by NOxconcentration levelFull scale at the experiment：1,000ppm

Measurement system (1)

NH3→NO NO2→NO det.

NO2→NO det.


Soft Ionization Mass Analyzer

（MS）- Identifying components by mass information of electrical charge and molecular weight, after ionizing materials - Generally batch measurement type, focusing on accuracy rather than response

Advantage：High accuracy

Disadvantage：Cost

Full scale at the experiment：100ppm


Fourier Transform Infrared spectroscopy（FTIR）

Analyzing magnitude of each components absorption in infrared band by Fourier transform

Advantage：real time, continuous and simultaneous multi components measurement

Disadvantage：cross sensitivity



Diode Laser Spectrometry（LDS）

Measuring absorption of NH3

Advantage: Response

Disadvantage: Exhaust pipe modification

-Less cross sensitivity of other components NH3-exhaust pope itself works as test cell, improving response by avoiding adsorption

Exhaust gas


Exhaust gas

Sampling NH3

Sample probes of DCLD, MS, and, FTIR are located within 30cm (one foot) from the tail pipe.

Exhaust gas Catalyst

exhaust gas

chassis-dynamometer

NOx,COTHC

D-CLD

MS

FTIR

Micro tunnel

data strage

heated line

GVW 25t9.2L, TCI

w/ urea SCR system

LDS

Vehicle speed etc.

fan

Experiment system

About exhaust gas measures for in-use vehicles

“Some metals used for catalyst such as vanadium, chromium, mangan, cobalt, nickel and copper have possibility of secondary disaster. These metallic components should not be emitted in the atmosphere.”

（12 of October, 1972,Exhaust Gas Measures WG, Motor Vehicle Division, Transport Technology Council, Ministry of Transport）

Materials for Vehicle’s Catalyst

Comparison of NH3 concentration (constant speed)

40km/h 60km/h 80km/h0

5

10

15

20

DCLD MS FTIR LDS

Vehicle speed

NH

3pp

m

Average NH3 conc.at 80km/h

NH3 was not observed under 60km/h conditions

Deviations are within about 1％ of each system’s full scale

NH3 measurement accuracy and response

DCLD has lager error when NOx chages rapidly

0 100 200 300

0

5

10

15

20

25

DCLD MS FTIR LDS

Time s

NH

3pp

m

Constant speed(about 80km/h)

LDS has less accuracy at low consentration

LDS has good response

FTIR has slow response

Periodical accelerator operation (arround 80km/h)

NH3 mass at D13 mode test

1 2 3 4 5 6 7 8 9 10 11 12 130

5

10

15

D-CLD MS FTIR LDS

NH

3g/

h145.9

total totalNOxmode # NH3

NH3 concentration at D13 mode test

1 2 3 4 5 6 7 8 9 10 11 12 130

5

10

15

20

D-CLD MS FTIR LDSN

H3

ppm

mode #

D-CLD MS FTIR LDS0

0.5

1[NH3]measured - [NH3]ave. >σ

[NH3]measured - [NH3]ave. >2σ

Pro

babi

lity

of O

ccur

renc

e

Sensitivity analysis of measurement systems

D13 mode

NH3 emission at various mode

JE05① JE05② JE05 JE05 D13 ETC0

0.01

0.02

0.03

0.04

DCLD MS FTIR LDS

NH

3g/

kWh

payload100%

payload0%

DCLD測定せず

Higher at steady mode

Note that Japanese 2005 NOx regulation is 2.0g/kWh !

did not measure with DCLD

Deference between same mode tests

NH3 concentration comparison (JE05 mode)

Catalyst temperatures and NOx emissions are about same but NH3 emissions are deferent.

Need some discussion about Pre-conditioning

DCLD indicates lager fluctuation when NOx changes rapidly.

MS and FTIR show about same trace and high total amount accuracy.

Only LDS indicates zero. Other are affected by previous NH3.

Only LDS indicates zero. Less sensitivity at low concentration.





5. Conclusion

Name MD92Type DI, TCICylinder #, valve type Inline 6, OHCDisplacement L 9.2Max. Power kW/rpm 272/2200Max. Torque Nm/rpm 1470/1400Injection system Common railAfter treatment device Urea SCR (w/ DOC)Vehicle Weight kg 16640 (half payload)

Engine specification

Engine

9.2L TCI272kW

DOC1 DOC2SCR

Direct/CVS

Powertrain system with urea SCRfor 2005 emission regulation

Exhaust gas

Equivelentexhaust pipe length to catalyst as real vehicle

Experiment system

Condition ID DOC1 SCR DOC2A ○ ○ ○B ○ dummy ○C ○ ○ dummyD dummy dummy dummy

DOC1 SCR DOC2Size L 8.5 8.5 5.7

Main Component Pt Fe (non Vanadium) Pt

dummy: Catalyst without metal componentsNH3 was measured by only LDS

Catalyst specification and setting conditions

NOx PM

2.29g/kWh

Japan 2005regulation

NOx, PMemission

0

High JE-05 cycle

!

NOx:2.0g/kWhPM:0.027g/kWh

A B C D

solid urea 98%


Emission test results (1)

0

20

40

60

80

100

0

200

400

600

800

1,000Average Maximum

NH

3 [a

ve.]

ppm

NH

3 [m

ax.]

ppm

JE-05 cycle

A B C D



A B C D

NOx PM

notmeasured*

Japan 2005regulation level

NOx, PMemission

0

High Japan D-13 mode

NOx:2.0g/kWhPM:0.027g/kWh







5. Conclusion

DCLD MS FTIR LDSAccuracy △～○ ◎ ○ ○

Response ○ △ × ◎

Price ○ × △ △

Peak during trasient mode × △ × ◎

Average concentration △～○ ○～◎ ○ ○

Total amount of emission △～○ ○～◎ ○ ○

-NH3 from vehicle with urea SCR system real time measurement was conducted using four types of exhaust gas analyzer-NH3 emission level was low, so it was difficult to evaluate absolute accuracy.-Characteristics of each measurement system were clarified-Overview of comparison is as follows。

Conclusion (1)

-When one of catalyst in urea SCR system stop function, not only NOx and NH3 but also PM may increase

-Most of PM is solid urea, when PM substantially increase in above case.

-If SCR catalyst is in deactivated condition, post oxidation catalyst (ammonia slip catalyst) can prevent NOx, PM, and NH3 from substantial increase.

Conclusion (2)

comparison of ammonia continuous measurement techniques ...€¦ · practical requirements by...

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