Biodiesel and 2010 Engine After Treatment Technology Steve Howell Technical Director National Biodiesel Board Presented at Alternative Fuels & Vehicles National Conference and Expo Tuesday, April 21, 2009
Biodiesel and 2010 Engine After Treatment Technology
Steve Howell Technical Director
National Biodiesel Board
Presented at Alternative Fuels & Vehicles National Conference and Expo
Tuesday, April 21, 2009
Biodiesel and Advanced Emission Controls
2010
• Thanks to Bob McCormick and Aaron Williams of NREL for much of the content of these slides
How will the 2010 standards be met? • Introduction of ultralow sulfur diesel fuel in October 2006 • October 2008 ASTM approves up to 5% biodiesel as D975 fuel
•B6 to B20 ASTM standard also approved by ASTM: D7467 • Intermediate EPA emissions standard for 2007:
•0.01 g/bhph for PM, 1.2 g/bhph for NOx •Diesel particle filters (DPF), unburned diesel fuel for regeneration • Increased levels of exhaust gas recirculation (EGR) and higher fuel injection pressures
• Full EPA emissions standard in 2010: •0.01 g/bhph for PM, 0.20 g/bhph for NOx •DPF, EGR, high pressure fuel injection •Exhaust catalysts for NOx reduction
•NOx adsorber catalysts, unburned diesel fuel for operation •Selective catalytic reduction (SCR)
•Diesel Exhaust Fluid (DEF) needed for SCR operation
Diesel Particle Filters • Exhaust flows through porous wallflow elements
– PM is trapped on the walls of the filter • When exhaust temperature is high enough, PM is burned off
– In most cases, unburned diesel fuel is injected to accomplish this • Precious metal is loaded onto filter walls to lower the
temperature required for regeneration • Issues:
– Regeneration at low temperatures/duty cycles – Plugging with incombustible materials like lube oil ash
Catalytic Control of NO x Emissions •NO x Adsorber Catalyst (or lean NO x trap –LNT) –Catalyst converts all NO x to NO 2 , adsorbent bed “traps” NO 2
–When bed is saturated, exhaust is forced “rich”
–NO 2 is released and converted to N2 –Bed also traps SO 2 , but doesn’t release it
• Near sulfur free exhaust is needed • Higher temps, longer time needed to release sulfur
–90%+ conversion is possible
•Selective Catalytic Reduction (SCR) –Used for industrial NO x control for many years
–Requires a supplemental “reductant” –Typically ammonia, derived from urea
• “Diesel Exhaust Fluid” –8090% reduction efficiency –Generally sulfur tolerant
NO x adsorber catalyst (NAC) is also known as a leanNO x trap (LNT)
SCR
NOx + NH3
Sensor
Urea
Injection
NBB 2007/2010 OEM Program
• Major NBB/DOE Collaboration via CRADA • Ongoing program areas:
– Lightduty diesel vehicle testing with DPF and NO x control
– Mediumduty engine testing with DPF and NO x control – Heavyduty vehicle testing with active regen DPF
• Ongoing and future program areas include additional MD and HD testing with DPF and NOx control systems, offhighway systems
Objective: Investigate the impact of B20 and lower biodiesel blends on 2007 and later fuel system, engine, and emission control technology
Biodiesel Testing with DPF – MD Engine • Cummins ISB 300
– 2002 Engine, 2004 Certification – Cooled EGR, VGT
• Johnson Matthey CCRT – 12 Liter DPF – Passively Regenerated System – Pre Catalyst (NO 2 Production)
• Fuels: ULSD, B100, B20, B5
• ReFUEL Test Facility – 400 HP Dynamometer – Transient & Steady State Testing
• Cummins – Soot Characterization – Significant financial support for
testing
B20 results in substantial PM reduction even with DPF (data for 2003 Cummins ISB with Johnson Matthey CCRT on HD FTP)
B20 Testing with DPF – HD FTP
Reduction with DPF ranges from 20% to 70%, depending on basefuel, test cycle, and other factors • Reduction in sulfate emissions • Increased PM reactivity
Williams, et al., “Effect of Biodiesel Blends on Diesel Particulate Filter Performance” SAE 2006013280
Balance Point Temperature/Regeneration Rate Results
BPT ULSD 360ºC B20 320ºC B100 250ºC
•BPT is 40ºC lower for B20 •Soot is more easily burned off of filter •B20 can be used for lower temperature duty cycle
• Regeneration rate increases with increasing biodiesel content
• Even at 5%, biodiesel PM measurably oxidizes more quickly
Biodiesel and DPF operation • Biodiesel is compatible with Diesel Particulate Filters, and has some distinct advantages: – Lowers regeneration temperatures – Less engine out particulate matter – May provide increased performance and decreased maintenance vs. ULSD alone
– May provide increased fuel economy • Regeneration mode is important
– Late incylinder injection may cause increased fuel dilution of engine oil and limit the level of biodiesel that can be used (i.e. B20 or B5)
– Most US heavy duty applications use exhaust stream fuel injection which is compatible with B20, perhaps higher blends
– NBB is working closely with OEM’s in this area
Biodiesel Testing with LD Emission Control Systems
• Includes two emission control systems and two fuel blends on a lightduty platform – NAC/DPF and SCR/DPF – 5% and 20 % biodiesel blends
• Performance, optimization and durability – Aging to represent 2100 hours of operation (approximately 120,00 miles or full useful life) for B20
– Emissions evaluations over UDDS, US06, and HFET –conducted by EPA
– Perform engine and fuel component teardown at end of aging
Engine: DCX OM646 Engine: DCX OM646 Vehicle: Mercedes C200 CDI Vehicle: Mercedes C200 CDI
PM [mg/mile]
0 1 2 3 4 5 6 7 8 9 10 11
NOx [g/mile] 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
Cold LA4 Hot LA4 Composite FTP75
120,000 mile Standard
50,000 mile Standard
Test Results – EPA Chassis Dynamometer NOx Adsorber Catalyst (NAC)
B20 PM
[mg/mile]
0 1 2 3 4 5 6 7 8 9 10 11
NOx [g/mile] 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
Cold LA4 Hot LA4 Composite FTP75
120,000 mile Standard
50,000 mile Standard
ULSD
Experimental Setup and Objectives: SCR
Urea Injection
Diesel Particulate
Filter DOC
Selective Catalytic Reduction
NH3 Slip Cat
Diesel Particulate Filter § JM CCRT (12 Liters) § Passively Regenerated § Pre Catalyst for NO 2 Production
Diesel Particulate Filter § JM CCRT (12 Liters) § Passively Regenerated § Pre Catalyst for NO 2 Production
§ Compare SCR catalyst performance with ULSD and Soy B20 through engine testing
§ Measure relative importance of catalyst temp, exhaust chemistry and catalyst space velocity
§ Measure B20’s impact on these system variables and overall NOx conversion
§ Focus on SteadyState Modal Testing
deNOx Aftertreatment § JM Zeolite SCR (15.5 Liters) § Urea Injection (air assisted) § NH3 Slip Catalyst
deNOx Aftertreatment § JM Zeolite SCR (15.5 Liters) § Urea Injection (air assisted) § NH3 Slip Catalyst
Diesel Engine § 2002 Cummins ISB (300 hp) § 2004 Emissions Cert § Cooled EGR, VGT, HPCR
Diesel Engine § 2002 Cummins ISB (300 hp) § 2004 Emissions Cert § Cooled EGR, VGT, HPCR
ULSD vs B20 – SCR Overall NOx Conversion
§ No statistical difference in NOx Conversion with B20
Conclusions: • NBB, the US Department of Energy, and the engine and vehicle manufacturers are expending significant resources to understand how biodiesel blends interact with new diesel emission controls
• Detailed testing thus far indicates B20 and lower blends are compatible with both diesel and NOx after treatment – Provides benefits in some cases
• B5 is now just part of normal D975 diesel fuel • Additional study is underway
– Quantify long term benefits of biodiesel blends – Late incylinder injection may cause fuel dilution – NBB is encouraging OEM’s to publicly support B20