canadian diesel fuel
DESCRIPTION
TRANSCRIPT
1
CANADIAN
DIESEL FUEL
CURRENT TOPICS
Dr. Andy Pickard
Senior Advisor, Fuels
Petro-Canada
North American
Council of
Automotive Teachers
2001
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DIESEL FUEL TOPICS
• Fuel Standards and Specifications;Canadian & American; OEM
• Emissions Issues
• Fuel Qualities <=> operations / problems
• Miscellaneous Diesel Fuel Issues
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CAN/CGSB-3.6 & -3.517
• National Standards of Canada for Regular Sulphur Diesel Fuel and Automotive Low Sulphur Diesel Fuel.
• Consensus standards
• Provinces must legislate for legal standing
• Minimum standard in practice.
• [www.pwgsc.gc.ca/cgsb]
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U.S. Diesel Fuel Standard
• ASTM D 975 - consensus standard– RSD & LSD
• State Responsibility
• California Diesel Fuel: “CARB Diesel”
• [www.astm.org]
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OEM FUEL SPECIFICATIONS
• Individual OEM companies may spell out fuel requirements
or recommendations.
• World Wide Fuel Charter
– EMA, AAM; JAMA; ACEA
– 4 categories of diesel fuel
– www.engine-manufacturers.org
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EMISSIONSEMISSIONS
EMISSIONS
• Driver: Air quality in urban areas.
• Particulates & Nitrogen Oxides (NOx)
• Forcing most engine and fuel changes.
• On-highway versus off-highway.
• Fuel: low sulphur & ultra low sulphur
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EMISSIONSEMISSIONS
EMISSIONS
• Major engine changes
– electronics
– higher fuel injection pressures
– timing changes / more soot
– EGR
– NOx catalysts and particulate traps
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IMPACTS on FUELS
• Electronics: hotter fuel; thermal stability;
fire safety issue.
• Injection pressure: lubricity / wear.
• Soot: lighter fuel / lower aromatics.
• EGR: --
• NOx catalysts: “no” sulphur.
• Particulate traps: lighter fuel / lower aromatics.
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FUEL QUALITIES:
OPERATIONS & PROBLEMS
Individual specification requirements
will be discussed, with implications
for diesel engine operations or
problems.
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FUEL QUALITIES:
OPERATIONS & PROBLEMS • CLEANLINESS !!!!
• Clean & Dry is critical, and is the most important single quality requirement!!
• Dirt / particles will plug filters, restrict fuel flow / power, and lead to wear in pumps and injectors.
• Water can cause rusting, corrosion, erosion, wear & catastrophic failure.
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CETANE NUMBER
• Diesel fuel combustion quality
• Higher cetane = quicker combustion
( shorter ignition delay )
• Cetane number = engine test result.
• Cetane index = calculation to predict cetane number.
• No correlation to fuel density.
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CETANE NUMBER
• 40 cetane number is minimum standard in North America ( typically 41 - 46 ).
• Higher cetane is desirable, but expensive.
• Cetane quality effects cold starting:– white smoke– warm-up (smooth or rough)– noise level
• Cetane requirement drops when engine hot.
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SYNCRUDE: OIL SANDS
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SULPHURin Diesel Fuel
• Organic sulphur compounds in crude oil.
• Regular (high) sulphur diesel = < 0.5 % S
( RSD, <5,000 ppm sulphur )
• Low sulphur diesel fuel = < 0.05 % S
( LSD; < 500 ppm sulphur )
• Ultra low sulphur diesel fuel = < 15 ppm S
( ULSD, June, 2006 )
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SULPHURin Diesel Fuel
• Sulphur in diesel fuel: burns to form SOx
• Corrosive to engine and exhaust system
SOx + H2O ---> H2SO3, H2SO4
• Air pollutant
• increases particulates
• degrades engine oil
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LOW SULPHURin Diesel Fuel
• Lower particulate emissions
• Lower SOx emissions
• Less engine / exhaust corrosion
• Less engine oil degradation(longer oil drain or better quality oil)
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LUBRICITY
• The ability of fuel to lubricate parts of fuel systems (pumps and injectors).
• Most fuels have good lubricity.
• Low lubricity fuels require lubricity additive in Canada (but not in U.S.).
• Laboratory lubricity tests are poor, and may not show the presence of additives.
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LUBRICITY
• Rotary and distributor pumps are most vulnerable.
• Unit or in-line units (which are oil-lubricated) are less effected by fuel lubricity, and more likely to be ‘gummed’ by excessive lubricity additive or reaction of additive with engine oil.
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VISCOSITY
• The “flow” property of diesel fuel;
• Minimum and maximum limits;
• Effects:nozzle spray pattern & droplet size;
“slippage” past pump;
possible filter restriction;
lubricity / wear.
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DENSITY: ENERGY CONTENT
• kg / L @ 15 ºC; typically 0.855 kg / L
• Energy content is related to density:
• Higher density = higher energy content
• Better fuel economy or higher power
• Total range only about 7 % in energy(0.800 to 0.875 kg / L)
• Typically < 2 % variation winter to summer.
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API GRAVITY(Obsolete term)
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TYPICAL TRUCK TERMINAL
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LOW TEMPERATURE PROPERTIES
• Cloud point normally used.
• Obsolete term: pour point.
• “2.5 % low end design temperature”(2.5 % of hourly temperature readings are lower than the design temperature.)
• Not required in U.S. D 975.
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DIESEL FUEL NAMES
• Names related to temperature:• Seasonal diesel fuel - seasonally adjusted.• Identified by Celsius cloud point.• Obsolete names: Diesel 40 or P-40
negative Fahrenheit pour point: -40 ºF.• Other names: Arctic Diesel / No. 1 Diesel /
Diesel 50 / “Diesel Light”,
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LOW TEMPERATURE PROBLEMS
• Icing: most common winter problem;ice crystals or layer of ice
plug fuel filter.
Note: engine may run for a while before stalling.
• Actions: change filter / drain water when warm; change fuel for winter fuel.
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WATER & ICE
• No free water, however• No limit on dissolved water.• Solubility of water in diesel fuel
decreases as the temperature drops.• Excess water separates as a haze or as
ice crystals, which cause fuel filter plugging.
• Action: drain any water while fuel is hot.
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LOW TEMPERATURE PROBLEMS
• Waxing or gelling: rare problem.
Wax crystals separate below cloud point and plug filter; eventually fuel ‘gels’ and goes solid.
Action: Warm up & change fuel; replace fuel filter.
(It takes a lot of kerosene to ‘cut’ waxy fuel!)
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LOW TEMPERATURE PROBLEMS
• Fuel flow restriction:
Symptom: engine runs but does not develop full power.
Causes: fine filtration; partly plugged filter; high viscosity fuel.
Actions: replace filter / use higher porosity filter; change fuel.
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DISTILLATION
• Boiling range of diesel fuel.
• Higher boiling (heavier) components increase soot and deposits.
• Only real “choice” is between Type B (No. 2 - heavier fuel;
seasonal diesel fuel) and Type A (No. 1 - lighter fuel).
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FLASH POINT
• The temperature of the fuel at which the vapours will burn when ignited with a spark or flame.
• Minimum +40 ºC; typically +50 to +70 ºC.
• Safety issue; not a diesel engine issue.
• Auto-ignition: 225 ºC
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HIBERNIA
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ELECTRICAL CONDUCTIVITY
• Safety issue: Canadian diesel fuels must have suitable conductivity to dissipate static electrical charges that may develop during pumping.
• Minimum 25 pS/m; typically > 100 pS/m
• Not a requirement in the U.S.
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OTHER REQUIREMENTS
These specification requirements are usually “non-issues”:
• Copper corrosion
• Acidity (total acid number)
• Carbon residue
• Ash
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MISCELLANEOUS
• “Bad Fuel”: usually the sign of a mechanic who does not know what’s wrong!
• Identify the real issue: e.g. dirt, water.
• Differentiate between symptoms and causes.
• Talk to local fuel suppliers!
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MISCELLANEOUS
“Bad Fuel” continued:
• When there is a genuine fuel quality problem, there are usually many vehicles effected.
• When a single vehicle is effected, it may be due to dirty or contaminated fuel in that vehicle, but not to ‘all fuel’.
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HARMONIZATION
• Harmonization of fuels:
Canada will follow U.S. fuel developments in order to benefit from lower emissions from new engine designs.
e.g. 15 ppm ULSD “at point of sale” for on-highway diesel fuel.
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QUALITY
• Quality Control / Quality Assurance
• Many refineries and laboratories are now following ISO 9000 practices to ensure quality products.
• Still work to be done on quality practices in distribution and at point-of-sale.
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QUALITY
PROBLEMS
• # 1 issue is cleanliness: clean & dry!!
• # 2 issue is water / ice at low temperatures.
• All other fuel-related problems are minor by comparison.
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INVESTIGATION of COMPLAINTS
• What is the problem? What was really observed, not possible causes.
• When did it start?
• Where is the problem?
• Where is the problem not occurring?
• Test possible causes for consistency.
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HEALTH & SAFETY
• Use normal ‘good hygiene’ practices in handling diesel fuel:
• Minimize skin contact.
• Remove any fuel-soaked clothing.
• Wash with soap and water before eating or smoking.
• See MSDS
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FUTURE DIESEL FUEL
• All changes driven by lower emissions.
• June 1, 2006: ULSD = 15 ppm sulphurfor on-road diesel fuel.
Harmonized with U.S.
• 2007?: off-road diesel fuel: 500 ppm S ?
• 2010?: possible limits on cetane / density / aromatics / < 10 ppm sulphur?
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QUESTIONS ??
• Are there any questions on fuel topics?
There are no silly questions…
There are only people who make
silly mistakes because they didn’t ask simple questions!
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HIGH QUALITY
DIESEL FUEL
Dr. Andy Pickard
Senior Advisor, Fuels
Petro-Canada
(403) 296-8019
North American
Council of
Automotive Teachers
2001