Automotive Diesel Oil and Heating Oil Flashcards
In France, what is the sulfur spec for HHO ?
1000 ppm
What is the problem with n-paraffins in Diesel ?
Very good combustion properties but low resistance to low temperatures
In N-paraffins, what is the link between carbon chain lenght and cristallization temperature ?
The longer the chain, the higher the cristallization temperature = the worst the resistance to low temperatures
What are the three measurements used to characterize a diesel cold flow properties ?
- Cloud point
- Cold Filter Plugging Point (CFPP)
- Pour point (not for ADO anymore)
What is the cloud point ?
The temperature at which a cloud appears in the test tube
What is the pour point ?
The temperature at which the product can no longer flow if the test tube is tilted for 5s
What are the cloud point specs for ADO ?
From October to March : -5°C
From April to September : +5°C
What are the specification for cloud and pour point of HHO ?
- Cloud Point : +2°C
- Pour Point : -9°C
What are the specs for CFPP for ADO?
From October to March : -15°C
From Qpril to September : 0°C
How can we improve cold flow properties of ADO ?
- change formulation (incorporate lighter HC like kerosene cut, nahthenes or aromatics) but negative effect on comubstion quality
- Additives like anti-settling additives (WASA)
What is the cetane number ?
The cetane number measure the ability of ADO or HHO to auto-ignite. The higher the cetane number, the shorter the ignition delay
Which family of components has the best cetane number ?
N-paraffins have a good cetane number
How is the cetane number measured ?
Cetane number is measure with a Diesel CFR engine and comparison with 2 references
What are the two references to measure cetane number ?
Good reference : nC16
Bad reference : hepta-methylnonane
How is the calculated cetane number estimated ?
Volatility (ASTM distillation) and chemical composition (density) are taken into account
What are the specifications for cetane number ?
- ADO : measured = 51 and calculated = 46
- HHO : measured = 40
Why are measured and calculated cetane number sometimes very different?
Because of the additives added in small quantities : measured effect on the CFR engine but too small quantities to impact calculated value
What are the ASTM distillation specs for ADO ?
- max 65% distilled at 250°C
- max 85% distilled at 350°C
- max 360 °C at 95% distilled
What is the spec for density of ADO ?
820 < d < 845 kg/m3 at 15°C
What is the spec for viscosity of ADO ?
2 < viscosity < 4.5 cSt at 40°C
Why are nitrogen impurities a problem for ADO ?
Some nitrogen compounds are gum precursors
Why is water a problem in ADO ?
It can damage the injection pump and the injectors and to reduce the risk of bacterial contamination
What is the spec for water content in ADO ?
200 mg/kg
What new problem arrived with low sulfur content in ADO ?
Low sulfur content means poor lubricating power of ADO
Which component is added to improve lubricating power lost by deep desulfurization ?
1-2% of vegetal oil ester
What is the flash point ?
The flash point is the minimum temperature at which fuel emits enough vapor to inflame in presence of an ignition source
What are the flash point specs for ADO and HHO ?
55 < flash point < 120 °C
Why do we have to control electrical conductivity of ADO ?
Because it facilitates the elimination of electrostatic charges created during transfer and enable to avoid any risk of inflammation
What is the spec for electrical conductivity in ADO ?
Min 150 pS/m at 20°C
What is the spec regarding sulfur content in ADO ?
Max 10 ppm
Why was a spec on sulfur content added and why so low ?
To protect catalytic converters used in modern vehicles
What are the pollutents contained in exhaust gas ?
CO2, SO2, CO, NOx, unburnt HC and particles
Why is polyaromatic content monitored in ADO ?
Because PAH are precursors for particles
What is the spec for PAH content in ADO ?
PAH content is now limited to max 8%
What are the two technologies which enable to meet the new specs for low NOx emissions ?
- Selective Catalytic Reduction (Adblue)
- Exhaust Gas Recycling (cheaper)
What are the biofuels used in ADO ?
Fatty Acid Methyl Ester (FAME)
What is the best oleaginous plant for FAME in ADO ?
Rape seed
What are the two problems with FAME ?
- Poor chemical stability
- Poor low temperature performance
What are the possibles bases for ADO and HHO ?
- LGO / HGO from atmospheric distillation
- LVGO from vacuum distillation
- Kerosene cut (cold flow properties)
- Distillate hydrocracking (high cetane + good stability)
- LCO from FCC
- Gas oil from visbreaking
- Oxygenated compounds
