Jet Fuels Flashcards
What is the average fuel consumption of an average plane at crusing speed ?
15 000 L/h or 12 t/h for a boeing 747
How is the fuel burnt in a plane ?
Auto-ignition at high T and P
In jet fuel, what are the measures taken to prevent water contamination ?
- Floatinf arms in the tanks
- 2 micron water separator micro-filter
What are the three most importants specifications for jet fuels ?
- Volatility
- Resistance to low temperature
- Combustion quality
What are the ASTM specs for jet fuel ?
- 10% distilled : max 205°C
- FBP : 300°C
- Losses < 1.5%
What are the two specs used to monitor the distillation column ?
- Flash point of the kerosene cut (separation between gasoline and kerosene)
- Freezing point of the kerosene cut (separation btween kerosene and LGO)
What is the spec of jet fuel regarding flash point ?
Flash point > 38°C
Why is flash point important ?
It’s a safety spec to improve safety during storage and transport
What are the specs for smoke point in jet fuel
- smoke point > 25 mm or >18 mm if naphthalene under 3%
- aromatic content < 25%
What is the specification for the calorific value of jet fuel ?
LCV > 42 800 kJ/kg
Why is there a calorific spec on jet fuel ?
To enable the pilote to calculate the amount of fuel he will need and not take too much (it makes the plane heavier and we then increase fuel consumption)
What is the density spec of jet fuel ?
Density at 15°C between 0.775 and 0.840 kg/m3
What is the viscosity spec of jet fuel ?
Viscosity at -20°C < 8 cSt
What is the freezing point spec of jet fuel ?
Freezing point < -47°C
What affects the freezing point of jet fuel ?
The higher the n-paraffin content the higher the freezing point :(
What is the maximum sulfur content tolerated in jet fuel (S and mercaptants) ?
- Sulfur < 0.3% = 3000 ppm (close to natural sulfur content of the kerosene cut)
- RHS < 30 ppm
What is the maximum acidity tolerated in jet fuel ?
0.015 mg KOH/g max
What is the unit that enables us to remove corrosivity problem of the jet fuel ?
Sweetening unit
What are the pollutants emitted from the consumption of jet fuel ?
CO, HC, particles and NOx
What is the spec on gum content of jet fuel ?
Actual gum content < 7 mg/100 mL
Why is water a problem in jet fuel ?
- It turns to ice at low temperatures
- it allows the development of micro-organisms that eat HC
What are the specs regarding thermal stability of the jet fuel ?
JFTOT (Jet Fuel Thermal Oxidation Test)
- deltaP max 25 mmHg
- visual control of deposits in heating tube
What is the only additive which is common in jet fuel ?
anti-static additive : STADIS 450
What is the maximum qtyof anti-static additive allowed ?
Max 3 mg/L
What is the usual yield of the kerosen cut ?
8 to 12 %
What other use can we have of the kerosene cut ?
It can be use in A.D.O
What is the family of components we don’t want in jet fuel and why ?
We don’t want aromatics to avoid deposits on the plane turbines
