jet fuel(redirected from Naphtha-type jet fuel)
jet fuel[′jet ¦fyül]
the fuel used in jet aircraft engines. The most common jet fuels are kerosine fractions obtained by straight-run distillation of low-sulfur and high-sulfur crude oils; examples of these fuels are the domestic jet fuels T-l (from low-sulphur crude oil) and TS-1 (from high-sulphur crude oil). Fuels with high thermal stability, such as the domestic fuel RT and the foreign fuels A, A-l, and B, are manufactured by hydrofining fractions derived from straight-run distillation. Other components used in the production of jet fuels are obtained by hydrocracking and the removal or conversion of mercaptans.
The most important properties of a jet fuel are its density and heat of combustion (see Table 1), which determine the flight range. A jet fuel should have high thermal stability, particularly if it is to be used in supersonic aircraft, where the temperature of the fuel in the tanks may exceed 150°-200°C. High thermal stability is attained by removing nonhydrocarbon impurities, such as sulfur, nitrogen, and oxygen compounds, from the fuel, for instance, by hydrogenation. Such processing (seeREFINING OF PETROLEUM PRODUCTS) also ensures that the jet fuel will have low corrosiveness.
In order to improve the stability of refined fuels during storage, antioxidants (up to 24 mg/liter) and additives to deactivate metals (6 milliliters/liter) are used. Jet fuels contain dissolved water (up to 0.008–0.01 percent at normal temperatures), which can separate from the fuel as conditions change, causing electrochemical corrosion in the fuel system or the formation of ice crystals. For this reason, corrosion inhibitors (10–45 mg/liter) and deicing additives (0.1–0.3 percent by volume) are used. Other additives prevent the accumulation of static electricity and improve the wear-inhibiting qualities of the fuel.
|Table 1. Basic physical and chemical characteristics of jet fuels manufactured in the USSR|
|Characteristic||Grade of fuel|
|*10,250 kilocalories/kg †10,300 kilocalories/kg|
|Density at 20°C (kg/m3)||≥800||≥775||≥775||≥840|
|10% distilled at (°C)||≤175°||≤165°||≤175°||≤195°|
|98% distilled at (°C)||≤280°||≤250°||≤280°||≤315°|
|Minimum heat ofcombustion (kilojoules/kg) … .||≥43,050*||≥43,050*||≥43,260†||≥43,260†|
|Onset of crystallization (°C)||≤–60°||≤–60°||≤–60°||≤–60°|
|Total sulfur content (%) .||≤0.10||≤0.25||≤0.10||≤0.05|
|Mercaotan sulfur content (%)||–||≤0.005||≤0.001||–|
REFERENCESNefteprodukty. Edited by B. V. Losikov. Moscow, 1966. Zrelov, V. N., and V. A. Piskunov. Reaktivnye dvigateli i toplivo. Moscow, 1968.
Zarubezhnye topliva, masla iprisadki. Edited by I. V. Rozhkov and B. V. Losikov. Moscow, 1971.
I. V. ROZHKOV