Compact ammonia storage systems for fuel-efficient NOX ... · PDF fileCompact ammonia storage systems for fuel-efficient NOX emissions reduction CTI conference on SCR Systems Stuttgart,

Compact ammonia storage systems for

fuel-efficient NOX emissions reduction

CTI conference on SCR Systems

Stuttgart, Germany

July 5th to 8th of July, 2010

© 2010 Amminex A/S 1CTI conference on SCR Systems

Ammonia enabling technologies

Dr. Tue JohannessenChief Technology Officer

Amminex A/S, Denmark

[email protected]

www.amminex.com

The environmental paradox: Low CO2 - but at the expense of NOX?

Annual mean nitrogen dioxide (ug/m3) in London

• NO2 is already today a problem in many European cities

• Focus on CO2 ⇒⇒⇒⇒ efficient engines:

• Efficient diesel engines ⇒⇒⇒⇒ Exhaust temperature often below 200°°°°C

⇒⇒⇒⇒ Significant challenge for off-cycle NOX control with AdBlue®

Improvements in future air quality?


http://www.dft.gov.uk/pgr/aviation/environmentalissues/heathrowsustain/chapter2monitoringandmeasure2911?page=6

Limit for 2010

0.6

0.8

1.0

NO

X c

on

ve

rsio

n r

ela

tiv

e t

o 2

00

°° °°C

NOX reduction potential at continuous low-temperature exhaust

• NOX conversion data with NH3

provided by Haldor Topsøe A/S

• Test conditions:– 250 ppm NOX

– Conversion measuredwith 20 ppm NH3 slip

– Space velocity: 63000 hr-1.

– Catalyst: Fe-zeolite; aged for 50hr at 750C

– NO2 content: NO2/NOX= 0.3

Urban NOx control

with ammonia gas

© 2010 Amminex A/S

0.0

0.2

0.4

150 160 170 180 190 200

NO

X c

on

ve

rsio

n r

ela

tiv

e t

o 2

00

SCR catalyst temperature (°°°°C)

NH3-dosing: Normalized

conversion (NO2/NOx=0.3)

AdBlue (inj. at Tscr >190 °C)

• Curve for AdBlue® is based on the assumption that:

– AdBlue® gives as high conversion as pure ammonia gas as long as injection is possible (urea hydrolysis complete)

– Steady-state AdBlue® injection requires an exhaust temperature of 190-200°C(e.g. Dr. Rusch: “Urea SCR – Interaction of spray

generation and exhaust system”,CTI Forum: SCR systems, Stuttgart, Oct. 08)

3CTI conference on SCR Systems

Illustration of urban NOX

control potential with

liquid injection (AdBlue®)

Fundamentally: NOX control by SCR

a) Reductant + 4NO + O2 → 4N2 + 6H2O

b) Reductant + 2NO + 2NO2 → 4N2 + 6H2O

Optimal reductant: Direct ammonia dosing

4NH3

4NH3


Optimal reductant: Direct ammonia dosing

However, liquid anhydrous ammonia is not safe

(approx. 8 bar at RT) as on-board storage

Safe but indirect ammonia storage: AdBlue®

AdBlue® as indirect ammonia storage

HNCO + H2O→ NH3 + CO2 (catalyst; T ≥ 200°C)

Urea → NH3 + HNCO (T > 160°C)

e.g. Dr Oliver Kröcher (CTI-meeting, SCR Systems)

Piazzesi et al., Catal. Com., 7, 600–603 (2006)


AdBlue® as indirect ammonia storage

implicate some challenges:- corrosive liquid; corrosive decomposition products in the exhaust line

- uncertainty in the degree of conversion to ammonia – urea chemistry

- risk of solid deposits (by-products)

- freezing issues (thawing strategy, heated lines, …)

- undesired urea decomposition in storage tank at T > 30-50°C

- dosing limitation at low exhaust temperature, e.g. urban driving

- exhaust design is complicated by need for well-defined spray patterns and mixers

- AdBlue® quality (“home-made”, impurities, etc.)

Core technology of Amminex:

Safe ammonia storage – controlled release on demand

• Amminex technology allows ammonia to be chemically stored with volume metric capacity similar to pressurized liquid ammonia.

• Volumetric ammonia capacity: ∼∼∼∼ 2.5 times higher than AdBlue®

• Molecular ammonia storage in AdAmmine is completely reversible

• Ammonia can be released on-demand by controlled thermal desorption

7⋅⋅⋅⋅NH3 1⋅⋅⋅⋅NH3

20°C 80°C 150°C

© 2010 Amminex A/S

• Non-pressurized at room temperature.

• AdAmmine is not hazardous goods for on-road, sea and air transportation.


Sr(NH3)8Cl2Sr(NH3)Cl2

7⋅⋅⋅⋅NH3

SrCl2

1⋅⋅⋅⋅NH3

1⋅⋅⋅⋅NH37⋅⋅⋅⋅NH3

(reversible) Material sample:

75 liter NH3-gas stored in a block

Amminex ASDS technology: Ammonia Storage and Delivery Systems

Amminex has developed three system variants:

• ASDS-1: Electrical system for small/medium cars

– Two smaller main cartridges pr. system

– Control strategy for low fuel economy impact

• ASDS-2/LD: Engine coolant system for medium/large cars

Main cartridge size is approx. ∼ 9 liters

© 2010 Amminex A/S

– Main cartridge size is approx. ∼ 9 liters

• ASDS-2/HD: Engine coolant system for MD/HD

– Main cartridge(s) is approx. 16 liters

– Modular system concept


ASDS TECHNOLOGY FOR PASSENGER CARS


Ammonia Storage and Delivery System – introductionCartridge heating by engine coolant

ASDS for passenger cars

Flow range: 0 – 4.5 g NH3/min (6 SLPM)

Average power consumption NEDC: 25W

Dosing time at from -27°C : 180 sec.

Ultra-pure ammonia gas delivered to exhaust lineStart-up

unit

Engine coolant

Main

AdAmmine

cartridge

System parts from automotive suppliers


SCR Catalyst

Ammonia Flow Manifold (AFM)

w. control electronics,

flow censor, P-sensor, valve Direct ammonia

gas dosing

ECU signal

Main cartridge is disconnected

and replaced at service

Engine coolant

circulation

(∼2 liter/min.

bypass)

- No injector needed;

-Steel-tube “penetrating” the pipe

- Simple exhaust geometry & short mixing length

- Low pressure drop

Dynamic NH3-dosing capability

• Proportional dosing of ammonia gas

– SCR reductant is not “pulsed”

• High turn-down ratio: 1:100

– Flow rate is either zero or [0.01-1] of max. demand

• Real-time “copy” of ammonia demand signal from

OEM (ECU)

• After cold start, system is ready for dosing well within

catalyst time-to-reach SCR light-off temperature

– also during freezing conditions.

AFM with gas

and com.

connectors

© 2010 Amminex A/S

– also during freezing conditions.


Controller: ASDS software and OBD

• Software development in Matlab-Simulink environment

– Overall system control strategy – state machine

– Control strategy & algorithms for AdAmmine cartridge heating

– Control of AFM (sensors & dosing valve)

– OBD functions of ASDS

• Overall responsibility for NOX control: The OEM

– OEM is responsible for SCR dosing strategy and overall OBD

– Link to engine map for engine-out NOX emission

© 2010 Amminex A/S

– Link to engine map for engine-out NOX emission

– Real-time ammonia dosing demand computed by OEM

• ASDS software can be located

– as layered object code in the engine control unit (ECU)

– as layered object code in a dosing control unit (DCU)

– on separate ASDS controller (e.g. integrated in the Ammonia Flow Manifold)


ASDS TECHNOLOGY FOR MD/HD


ASDS-2/HD for commercial vehicle or truck

• Max. peak flow of ammonia: 11 g NH3/minute.

• Max. steady state flow: 9 g NH3/minute

• AdAmmine cartridge with ∼7kg available NH3.

• Modular system configuration possible

Start-up

unit (electrical)Ammonia Flow Manifold

(AFM)Engine coolant

circulation


Main

AdAmmine

cartridge

circulation

(∼2-4 liter/min.

bypass)

Ammonia gas line

(to exhaust line interface)

EXAMPLES OF VALIDATION ACTIVITEIS


Status on ASDS validation activities

• Dynamic dosing according to NH3-demand profiles (engine dyno and vehicles)

• ∼ 200,000km combined on-road system tests– 10+ passenger cars

– One complete oil service interval has been demonstrated with an AdAmmine cartridge.

– Several trucks

• Fire test of fully saturated cartridge (20 minute duration “car fire” test)

• Climate (temperature)

© 2010 Amminex A/S

• Climate (temperature)

– Dosing from -27°C cold soak temperature

– Exposure to hot climate conditions (“Arizona”)

• Vibration tests– focusing on AdAmmine cartridge

– Still on-going with different OEM specs.

• Verification of on-board recharging of start-up unit– Consistent start-up times during extended stress testing of start-up unit


Cold climate: No issues of freezing/thawing liquid reductant

• Both LD and MD/HD systems show

fast start-up time (time-to-dose)

• ASDS is ready within the time frame

of the SCR catalyst reaching light-off

temperature.

Min

ute

s

LD application


Start-up unit

Main

HD cold start conditions: -10 °C

Start-up unit: Endurance test

• PTC-heated SrCl2 -STU with ammonia

capacity of 82g.

• Cycles:

- startup to 3bar

- dosing of NEDC cycle

- dosing constant flow (20mg/s) until

50% filling level

• Re-saturation

• Unit is weighed to check that capacity is

unchanged


Results

• The startup time was very stable over the

whole testing period

• Resaturation up to almost 99% was

possible over the whole testing period

Post mortem analysis

• No changes in the salt, as an effect off the

endurance test, were observed

Short-distance driving: Start-up unit recharging

• One OEM has demonstrated positive ammonia mass balance of the start-up unit in a

∼ 6km driving cycle from (cold start). Start-up unit was 75% saturated.

• Room temperature:

– 10 minute driving

– 0.6g NH3 consumed from start-up unit and 1.5g NH3 resaturated from main unit.

• Low-temperature (-15 °C)

– Engine start, ice-scraping and subsequently 6km driving was performed

– 2.8 g NH3 consumed from start-up unit and 5g NH3 resaturated from main unit.

© 2010 Amminex A/S

– 2.8 g NH3 consumed from start-up unit and 5g NH3 resaturated from main unit.


Integrated flow sensor signal: Cartridge “filling level”

• Several experiments of degassing of both passenger car cartridges (∼4kg NH3) and HD

systems demonstrated accurate level monitoring based on integrated signal from flow

sensor.

1. ASDS-2/LD : 4 kg dosed: ∼ 0.3% error

2. ASDS-2/LD : 3.9kg dosed: ∼ 1% error

3. ASDS-2/HD system: 17.8kg dosed (∼ 2.2% error)

This accuracy is mainly dependant on the calibration of the sensor.

© 2010 Amminex A/S

This accuracy is mainly dependant on the calibration of the sensor.


NOX REDUCTION PERFORMANCE


ASDS-1: Example of NOX control on OEM vehicle

• High SCR NOX performance on light vehicle with small diesel engine

• SCR positioned under-floor

• Dosing strategy for Amminex system fine-tuned for ammonia gas

• Options for significant improvement on tailpipe NOX emissions possible compared with

AdBlue

OEM data: Light vehicle


Euro 6 NOx levelEuro 6 NOx level

OEM data: Light vehicle

ASDS-2/LD: Performance on OEM test vehicle during FTP

Start-up unit:

Ready to dose after ∼∼∼∼ 30-40 sec.

Dosing from main unit “takes over”.

Start-up unit resaturation initiated

Coolant temperature for the main

cartridge heating (by-pass loop)


Low power consumption in the electrically heated start-up unit;

15-25 watt on average in 20-30 minute driving cycle.

ASDS-2/LD: NOX control on OEM test vehicle: NEDC fulfilled

NH3-dosing initiated at much lower catalyst temperature (early in

the NEDC cycle) compared to what is possible with AdBlue

No ammonia slip

High conversion

around SCR temperature

of 200°°°°C


ASDS-2/LD: NOX control on OEM test vehicle: FTP75 fulfilled

NH3-dosing initiated at low TSCR

Almost 100% NOx conversion at 225-250°°°°C Immediately high

conversion in 2nd

part of FTP

Little or no ammonia slip


ASDS-2/HD: Extending the SCR application range !

150

200

250u

re [

°C],

Sp

eed

[k

mp

h]

SCR_avg_T [°C]

NOx_conversion [%]

Vehicle_speed [kmph]

Ammonia_dosed [mg/s]

Catalyst

temperature

NO

x co

nve

rsio

n /

Ca

taly

st t

em

pe

ratu

re (

°C

) /

Sp

ee

d (

km/h

r) /

Am

mo

nia

do

sin

gRequired catalyst temperature

for operating AdBlue:

> 200°C

Urban driving pattern

for more than one hour

with reliable NOX

performance.

Performance enabled

by gaseous ammonia

dosing.


0 500 1000 1500 2000 2500 3000 3500 4000 4500

Time [s]

0

50

100

Flo

w [

mg

/s],

Te

mp

era

tu

High NOX conversion

possible with continuous

cold exhaust temperature

using AdAmmine-SCR

NO

x co

nve

rsio

n /

Ca

taly

st t

em

pe

ratu

re (

Sp

ee

d (

km/h

r) /

Am

mo

nia

do

sin

g

Solid reductant cartridge for Tier 4 ?

OEM

• Typically, a large variation in exhaust line configurations challenges the inlet zone of the

reductant (injection/spray)

• Gaseous ammonia inlet zones can be done with no risk of deposits

– Both straight or bended tubes

• Potentially move SCR catalyst closer to the heat

– Shorter mixing zone

User/Owner

© 2010 Amminex A/S

User/Owner

• Reductant does not require establishment of liquid handling/storage on e.g. the -

sometimes temporary - point of use.


INDUSTRIALIZATON


AdAmmine processing


First facility for series production

• First commercial contract landed

• Amminex has developed production methods for full-scale cartridge production

• Basic design for full-size plant with two production lines is established

• Full-scale production trial run to take place in 2011 in a Danish facility


Raw Materials

Ammonia

• Worlds most produced chemical 146.5 million t/year

• Extensive production and distribution

Anhydrous strontium chloride

• Occurrence– Celestite SrSO4 , annual production in excess of 300.000 t/year

– (Strontianate SrCO3)

– Mining in Spain, Turkey, China, Mexico

© 2010 Amminex A/S

• Low toxicity: Strontium chloride ‘behaves’ like calcium chloride with LD50 ~2000mg/kg body weight

• Other uses of strontium chloride– Additive to toothpaste for sensitive teeth

– Medical against osteoporosis

– Intermediate for production of other strontium compounds


Servicing strategy and aftermarket

• Standard production method: First-fit cartridges on new vehicles

• Cartridge replacement:

Depleted cartridge exchanged with a full unit (e.g. at OEM service station or fleet)

• Depleted cartridges can be:

– Resaturated at a decentralized facility (however not directly at OEM dealer or Fleet)

– Once “exhausted”, a cartridge can be recycled completely with full utilization of raw materials.

© 2010 Amminex A/S

• The AdAmmine “aerosol can”

– For certain applications, the cartridge strategy may be complete recycle because the value of the

“housing” is low compared to the additional efforts of quality assuring a cartridge in a resaturation

scenario.


Aftermarket: AdAmmine cartridges – similarities with propane distribution

Propane canister

(one-time use)

0.5-1kg propane

Price in retail: $2.5-3 EUR

(Including VAT)

Propane bottle

(refill)

11kg propane

Price in retail: 11-13 EUR

Propane transported in bottles:

hazardous goods (logistics “risk fee”)

Solid AdAmmine cartridges:

not hazardous goods


Numerous application examples exist with fast bottle replacement


Illustration of infrastructure and responsibilities

• High-capacity cartridges allows SCR reductant to be “maintained” only during serving or via limited infrastructure.

• AdAmmine cartridges are OEM spare parts; can be distributed via normal dealer/OEM infrastructure or networks similar to propane bottles

• AdAmmine technology allows OEMs to strengthening the the relationship

© 2010 Amminex A/SCTI conference on SCR Systems

Refill facility

First fit/Recycle facility

(e.g. 1:10 is “new”)

strengthening the the relationship between themselves and the customers

– No additional burden on driver

– AdAmmine replacement at certified dealers/workshops with strong links to OEM.

• Emissions responsibility is moved from the driver to the OEM/Fleet

– Important for authorities

– Potential for tampering with emissions reduction system is very low

Summary

• On-board storage of NH3 is enabled by AdAmmine technology.

• Approx. 2.5 times lower installed system volume compared with AdBlue®.

• Dynamic and accurate NH3 dosing. No injector needed at exhaust interface.

• Reliable SCR performance at low-temperature exhaust during urban driving

– No limitations due to urea hydrolysis or risk of deposits

• AdAmmine does not degrade during long-term storage

• AdAmmine replacement cartridge is an OEM/service spare part

• Vehicle integration: Clear split of responsibilities




• Fuel-efficient NOx control technology

Thank you for your attention


Ammonia enabling technologies

Documents

Compact ammonia storage systems for fuel-efficient NOX ... · PDF fileCompact ammonia storage systems for fuel-efficient NOX emissions reduction CTI conference on SCR Systems Stuttgart,