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Diesel Emissions and Exhaust After-Treatment for Modern Diesel Technology National Biodiesel Board Technician Outreach Program Rachel Burton & David Stehouwer 2009
18

Biodiesel and Exhaust AfterTreatment

Sep 11, 2014

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Page 1: Biodiesel and Exhaust AfterTreatment

Diesel Emissions and Exhaust After-Treatment for Modern Diesel Technology

National Biodiesel Board Technician Outreach Program

Rachel Burton & David Stehouwer 2009

Page 2: Biodiesel and Exhaust AfterTreatment

Today’s Topics

Changes in diesel engine emissions regulations

Basics of diesel engine emissions Changes in hardware required by emissions

regulations Interactions of fuels and fuel systems

Methods of exhaust aftertreatment Exhaust aftertreatment & biodiesel Resources

Page 3: Biodiesel and Exhaust AfterTreatment

US On Highway Emissions Standards

19881990

19911994

19982000

2002

20100.80

0.330.134

0

2

4

6

8

10

12

NO

x, g

/kW

-Hr

Particulate, g/kW-Hr

8.058.056.76.76.76.7

5.45.4

3.33.3

1.51.5

0.0130.013

14

1614.414.4

2007

0.270.27

Page 4: Biodiesel and Exhaust AfterTreatment

Fuel technology

Combustion technology

Aftertreatment technology

Fuel system technology

Better understanding of combustion

Alternate Fuels (Biodiesel)Low sulfur De-NOx

DOC

PM trap

Rate controlHigh pressure Multi-injection

EGR technology

Others

Control technology

Emission Reduction in Diesel Engines

Page 5: Biodiesel and Exhaust AfterTreatment

Injection performance

Higher injection pressure 1600-2000+

bar

Multiple injection

• NOx, PM control

• Noise control

• Aftertreatment dosing, trap regen

Injection Rate Control

Soft SOI Better BSFC/NOx tradeoff

Sharp EOI Better PM/smoke control

Precise injection control – minimum

variation

Minimum emission variation

Tamper resistant

Stable over useful life (>8000 hours)

Summary of Requirements for High Pressure Common Rail Fuel System

Time

Nee

dle

lif

tP

ress

ure

at

nee

dle

sea

t

Noise

NOX

Aftertreatment

Soot

Increased injection pressure

Page 6: Biodiesel and Exhaust AfterTreatment

Injection performance Higher injection pressure

1600-2000+ bar Significant increases in fuel

economy• At equivalent emissions

Summary of Requirements for High Pressure Common Rail Fuel System (cont’d)

Increasing Injection Pressure

200 bar

2

4

6

8

Fu

el E

con

om

y Im

pro

vem

ent

(%)

Increasing Injection Pressure

200 bar

2

4

6

8

Fu

el E

con

om

y Im

pro

vem

ent

(%)

Time

Page 7: Biodiesel and Exhaust AfterTreatment

Fuel properties effects on Common Rail FIE

• Startability• Accurate SOI• Controlled HR

• Leakage control• Pressure control• Durability/Fatigue• Filter plugging

• Gumming, sticking• Deposits • Filter plugging • Corrosion / Wear

Specified Fuel properties: chemical, contamination, physical

Cetane # Density Aromatics & Volatility

Sulfur Flash Pt

Hard Particle and ashcontamination

Watercontamination

OxidationStability

Lubricity

Viscosity

Fatty Acid Methyl Esters

• Pressure control

• Quantity control

• Elastomeric compatibility

• Cavitation damage

• Corrosion• Acid oxidation• Catalyst poisoning• Smoke & Particulates

• Fire Hazard• Spill

Hazard• Spark

Hazard

• Wear• Scuffing• Seizure

• Gumming, sticking• Deposits • Filter plugging • Corrosion & Wear

• Rough running (misfire)

• Corrosion • Wear

• Abrasive Wear • Filter plugging

OTC and Refiner Additives• Anticorrosion• Cetane improvers• Cold flow improvers• Lubricity improvers• Conductivity improvers

Refining process contaminants• Catalysts• Desulfurization agents• Cross contamination

Distribution and storage process contaminants• tank bottoms * pumps, pipes• microbial * corrosion• algae *varnish/sludge

Page 8: Biodiesel and Exhaust AfterTreatment

Biodiesel Specifications Minimize Concerns

Oxidation Stability Gumming and sticking Fuel system deposits Corrosion and wear

Total and Free Glycerin Corrosion & Wear Filter plugging

Water Content Shortened injector life

Page 9: Biodiesel and Exhaust AfterTreatment

Water in Fuel is a Problem

All non-dissolved water can cause problems:

Serves as growth medium for organisms that plug filters

Concentrates acids and ionic species that cause corrosion and deposits

Freezes at cold temperatures and reduces fuel flow

Reacts with some additives to form precipitates and deposits

Plugs injector nozzles at extreme conditions

Reduces fuel lubricity when in emulsified form

0

50

100

150

200

250

300

Inje

ctor

Life

(%

)

25 100

200

400

500

750

1000

5000

10000

Amount of Water in Fuel (ppm)

Effect of Water on Injector Life

Page 10: Biodiesel and Exhaust AfterTreatment

Fuel-Water Removal More Difficult in Future

ULSD additive package lowers interfacial tension making removal more difficult

Biodiesels have lower interfacial tension and hold more water, again adversely impacting removal FWS more challenging as

biodiesel percentage in blends increase

Solvency of biodiesel blends makes coated cellulose media option less effective

0

20

40

60

80

100

120

0 10 20 30 40

interfacial surface tension, dynes/cm

tim

e w

eig

hte

d e

ffic

ien

cy,

%

original or clay treated fueladditized

more additized

ULSD

BiodieselB20 50

Page 11: Biodiesel and Exhaust AfterTreatment

Exhaust Aftertreatment for Emissions Control Diesel Particulate Filters (DPF)

Non-Catalyzed Traps Catalyzed DPF

NOx Adsorber Technology Solvent Catalyzed Reduction (SCR)

Page 12: Biodiesel and Exhaust AfterTreatment

Diesel Particulate Filter (DPF) Maintenance

Carbon particulates are burned off with on-board regeneration

Ash remains in the DPF and must be removed periodically This requires removal from vehicle

Page 13: Biodiesel and Exhaust AfterTreatment

Catalyzed Diesel Particulate Filter (CDPFs)

Uses chemicals in exhaust to continuously burn carbon in Soot Filter

Must still be removed to clean ash

NONO2 2 Oxidizes Soot in FilterOxidizes Soot in Filter

2NO2NO22 + C + C CO CO22 + 2NO + 2NONONO2 2 Oxidizes Soot in FilterOxidizes Soot in Filter

2NO2NO22 + C + C CO CO22 + 2NO + 2NO

ConvertsConvertsNO NO 2NO 2NO22

ConvertsConvertsNO NO 2NO 2NO22

Soot FilterSoot FilterSoot FilterSoot FilterPlatinum Catalyst Platinum Catalyst

Exhaust Gas Exhaust Gas

Page 14: Biodiesel and Exhaust AfterTreatment

NOx Adsorber Technology

Filter removes particles LNA absorbs NOx on lean operation Controls switch to rich operation to NOx to harmless Nitrogen Filter regeneration and LNA regeneration are separate Complex; costly; & fuel economy loss

Filter

Diesel Injector

NOx Sensor

DOCValves

DOC

Diesel Oxidation Catalyst

LNA

BypassReference: Volvo

Page 15: Biodiesel and Exhaust AfterTreatment

Selective-Catalysts Reduction (SCR)Aqueous UreaSolution Tank

AmmoniaSlip

Catalyst Engine

12

34

56

T

Air Induction

Pump and Injector

Atomized Urea

Solution

Catalyzed Particulate

Filter

SCR Catalyst

Air to Air CoolerC

Reference: DDC

Turbo-Charge

NO EGR

Page 16: Biodiesel and Exhaust AfterTreatment

Selective-Catalysts Reduction (SCR)

Uses aqueous Urea instead of fuel to convert NOx to Nitrogen Requires extra tank etc. Must add Urea distribution system to supply chain

Reduced EGR or no EGR Fuel economy gains compared to NOx

Adsorber Proven durability for European applications Favored by some for large truck and

stationary applications

Page 17: Biodiesel and Exhaust AfterTreatment

What Will Be in the Marketplace?

All of the above! Particulate Traps (or Soot Filters)

were across the board in 2007 NOx Adsorbers are on some pick-up

truck applications SCR is favored for many HD truck and

stationary applications

Page 18: Biodiesel and Exhaust AfterTreatment

How Does Biodiesel Effect Emissions & Aftertreatment ?

Fuel System Concern over deposits and corrosion Addressed by ASTM specifications

Engine Emissions Lower HC and Particulate NOx emissions depend on duty cycle

Aftertreatment hardware / durability Easier DPF regeneration Studies at NREL / ORNL show no adverse

effects on hardware durability