In jet fuel

Solubility of water in jet fuels as a function of temperature (Jet A is a variant] of Jet Al, used in the USA for domestic flights. Jet A has a freezing point higher than that of Jet Al). ... 

Finally, note that hydrocracking is ideal for obtaining middle distillate cuts that can be used in jet fuel formulation. 

Kerosene is heavier than gasoline and lighter than gas oil. The lighter portion of kerosene is most suitable as an illuminant for lamps. The heavier portions of kerosene traditionally have been used as stove oil. Since the 1950s, kerosene has been used as a major component in jet fuel. 

If chemicals and gasoline represent the high-growth areas for petroleum, the other petroleum products, for the most part, did not perform quite as well. The exception was kerosene. Output of kerosene rose from 100 million barrels in 1949 to over 200 million barrels in 1959, a result of increased demand in jet fuel. At the same time, demand for fuel oil declined as customers switched to natural gas. 

Methanol is also formed as a byproduct when charcoal is made by heating wood in the absence of air. For this reason, it is sometimes called wood alcohol. Methanol is used in jet fuels and as a solvent, gasoline additive, and starting material for several industrial syntheses. It is a deadly poison ingestion of as little as 25 mL can be fatal. The antidote in this case is a solution of sodium hydrogen carbonate, NaHC03. 

Aromatics, olefins and in general, unsaturated compounds undergo hydrogenation reactions, usually unwanted due to their detrimental effect on the operating costs, derived from an excessive consumption of hydrogen. Aromatic saturation, however, is used in jet fuel to improve the smoke point and in diesel for cetane enhancement. In the case of gasoline, extreme hydrogenation leads to a deterioration of the fuel performance parameters. 

Ramos, G., et al., Platelet activating factor receptor binding plays a critical role in jet fuel-induced immune suppression, Toxicol. Appl. Pharmacol., 195, 331, 2004. 

Low-resolution nuclear magnetic resonance spectroscopy can also be used to determine percent by weight hydrogen in jet fuel (ASTM D3701) and in light distillate, middle distillate, and gas-oil (ASTM D4808). As noted above, chromatographic methods are not applicable to naphtha, where losses can occur by evaporation. 

Jet fuels are blended primarily from straight-run distillate components and contain virtually no olefins. Aromatics in jet fuel are also limited. High aromatic content can cause smoke to form during combustion and can lead to carbon deposition in engines. A total aromatic content >30% can cause deterioration of aircraft fuel system elastomers and lead to fuel leakage. 

Oxygen-containing impurities such as phenols and naphthenic acids can adversely affect water separation properties and initiate gum formation. No limit presently exists to control the amount of oxidized organic compounds found in jet fuel. However, tests for existent gums, neutralization number, and water separation indirectly limit the presence of oxygenated materials in jet fuel. 

These determinations help to predict whether fuel viscosity, density and trace contaminants such as sulfonic and naphthenic acids work together to retain water and/or fine particulate matter in jet fuel. Veiy small traces of free water or particulates could result in ice formation and adversely affect jet engine operation. 

Anti-Static Additive - dissipates static charge in jet fuel. Static charge buildup can result in unwanted ignition of jet fuel/air mixtures. Use is normally not permitted in aviation gasoline except in Canada and Britain. Use is permitted in civil jet fuel and mandatory in military jet fuel. 

Microbiocides - used to prevent microbial growth in jet fuel. The only product approved for use in jet fuel is Biobor JF. However, its use is permitted only infrequently. The maximum treat rate is 270 mg/L. 

Fuel system corrosion inhibitors must have a low tendency toward emulsification with water and toward foam enhancement in turbulent systems. These properties are especially critical whenever inhibitors are used in jet fuel. The sensitivity of jet fuel pumping and injection systems requires that fuel be free of emulsions and foam. 

The ASTM D-3948 Water Separation Index, Modified (WSIM) Test is used to identify the emulsifying tendencies of additives in jet fuel. A high concentration of film-forming corrosion inhibitors has been shown to severely degrade the water separation tendencies of jet fuel. Treat rates as low as 20 ppm of some inhibitors can degrade the WSIM to a failing rating. 

Ethyleneglycol monomethylether (EGME) and diethyleneglycol mono-methylether (DEGME) are both approved as additives to help prevent ice crystal formation in jet fuel. At a maximum treat rate of 1500 ppm, these compounds have minimal effect on degrading the jet fuel MSEP rating. 

Another possible solution to the problem of high temperature stability is the use of additives. Not exactly a stranger to petroleum people (as evidenced by use in gasoline and lubricants) they generally fall into two classes metallic and non-metallic. The former, for the most part are metal salts of sulfonates or naphthenates, whereas the latter are either amines or amine derivatives (later other organics may prove more effective) Use of additives in jet fuels, however, must of necessity be approached with caution. As surface active materials, many have a variety of uses and properties. Hence, they must not introduce new problems such as foaming at high altitudes, emulsification, or interference with low temperature flow. These could easily be severe limitations, but additives are under serious consideration thruout the industry... 

The patent literature on jet fuels is very extensive. Some examples of patents granted on jet fuels are as follows Fox Britton (Ref 2) claim the incorporation of viscosity-index improvers in jet fuels to improve engine start-up combustion efficiency over a wide range of temps. Materials claimed to be effective are ethyl glycol, Acryloid Sanotex... 

Table 4.3- Changes in the number of hydrocarbon degraders with time in jet-fuel-contaminated loam soil ...

Chao KK, Child CA, Grens EA, Williams MC (1984) Antimisting action of polymeric additives in jet fuels AIChE J 30 111... 

MINOR NONHYDROCARBON COMPONENTS. Sulfur compounds and gum (insoluble or soluble) are present in jet fuels and can affect coke formation. The effects of sulfur are not always consistent, but, in general, sulfur is not considered to be a problem until 1% or more is present. However, no more than 0.4% of sulfur is permitted in current fuels specifications. Gum causes a small increase in coke deposits, but this effect is insignificant for fuels meeting gum specifications. 

Leonard, J.T., andBogardus, H.F., Pro-Static Agents in Jet Fuels, NRL Report 8021, Naval Research Laboratory, Washington DC, August 16, 1976. 

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