Page 111 - Synthetic Fuels Handbook

FUELS FROM PETROLEUM AND HEAVY OIL 97

Kerosene and Related Fuels. Kerosene (kerosine), also called paraffin or paraffin oil, is a
flammable pale-yellow or colorless oily liquid with a characteristic odor. It is obtained from
petroleum and used for burning in lamps and domestic heaters or furnaces, as a fuel or fuel
component for jet engines, and as a solvent for greases and insecticides.
Kerosene is intermediate in volatility between gasoline and gas oil. It is a medium oil
distilling between 150 and 300°C (302 and 572°F). Kerosene has a flash point about 25°C
(77°F) and is suitable for use as an illuminant when burned in a wide lamp. The term kero-
sene is also too often incorrectly applied to various fuel oils, but a fuel oil is actually any
liquid or liquid petroleum product that produces heat when burned in a suitable container
or that produces power when burned in an engine.
Jet fuel is a light petroleum distillate that is available in several forms suitable for use
in various types of jet engines. The major jet fuels used by the military are JP-4, JP-5,
JP-6, JP-7, and JP-8. Briefly, JP-4 is a wide-cut fuel developed for broad availability.
JP-6 is a higher cut than JP-4 and is characterized by fewer impurities. JP-5 is specially
blended kerosene, and JP-7 is high flash point special kerosene used in advanced super-
sonic aircraft. JP-8 is kerosene modeled on Jet A-l fuel (used in civilian aircraft). From
what data are available, typical hydrocarbon chain lengths characterizing JP-4 range
from C to C . Aviation fuels consist primarily of straight and branched alkanes and
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cycloalkanes. Aromatic hydrocarbons are limited to 20 to 25 percent of the total mixture
because they produce smoke when burned. A maximum of 5 percent alkenes is speci-
fied for JP-4. The approximate distribution by chemical class is: straight chain alkanes
(32 percent), branched alkanes (31 percent), cycloalkanes (16 percent), and aromatic
hydrocarbons (21 percent).
Gasoline-type jet fuel includes all light hydrocarbon oils for use in aviation turbine
power units that distill between 100 and 250°C (212 and 482°F). It is obtained by blend-
ing kerosene and gasoline or naphtha in such a way that the aromatic content does
not exceed 25 percent in volume. Additives can be included to improve fuel stability and
combustibility. Kerosene-type jet fuel is a medium distillate product that is used for aviation
turbine power units. It has the same distillation characteristics and flash point as kerosene
[between 150 and 300°C (302 and 572°F)], but not generally above 250°C (482°F). In
addition, it has particular specifications (such as freezing point) which are established by
the International Air Transport Association (IATA).
Chemically, kerosene is a mixture of hydrocarbons; the chemical composition depends
on its source, but it usually consists of about 10 different hydrocarbons, each containing
from 10 to 16 carbon atoms per molecule; the constituents include n-dodecane (n-C H ),
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alkyl benzenes, and naphthalene and its derivatives. Kerosene is less volatile than gasoline;
it boils between about 140°C (284°F) and 320°C (608°F).
Although the kerosene constituents are predominantly saturated materials, there is evi-
dence for the presence of substituted tetrahydronaphthalene. Dicycloparaffins also occur
in substantial amounts in kerosene. Other hydrocarbons with both aromatic and cyclopar-
affin rings in the same molecule, such as substituted indan, also occur in kerosene. The
predominant structure of the dinuclear aromatics appears to be that in which the aromatic
rings are condensed, such as naphthalene whereas the isolated two-ring compounds, such
as biphenyl, are only present in traces, if at all.
Kerosene is now largely produced by cracking the less volatile portion of crude oil at
atmospheric pressure and elevated temperatures.
In the early days, the poorer quality kerosene was treated with large quantities of sul-
furic acid to convert them to marketable products. However, this treatment resulted in high
acid and kerosene losses, but the later development of the Edeleanu process overcame these
problems.
Kerosene is a very stable product, and additives are not required to improve the qual-
ity. Apart from the removal of excessive quantities of aromatics by the Edeleanu process,