Kerosene atmospheric distillation unit

Jet fuels are typically prepared from either straight-run kerosene or from wide-cut kerosene/naphtha blends off of the atmospheric distillation unit. TABLE 3-10 briefly describes the composition of some typical jet fuel grades. 

Jet fuel is kerosene-based aviation fuel. It is medium distillate used for aviation turbine power units and usually has the same distillation characteristics and flash point as kerosene. Jet fuels are manufactured predominately from straight-run kerosene or kerosene-naphtha blends in the case of wide cut fuels that are produced from the atmospheric distillation of crude oil. Jet fuels are similar in gross composition, with many of the differences in them attributable to additives designed to control some fuel parameters such as freeze and pour point characteristics. For example, the chromatogram (Figure 27.4) of a commercial jet fuel (Jet A) is dominated by GC-resolved n-alkanes in a narrow range of n-C-j to n-Cig with maximum being around n-Ci. The UCM is well dehned. 

Atmospheric distillation of the best crudes yields about 60% naphtha plus middle distillates (kerosene and gas oil), but the average is closer to 40%. In contrast. Table 9 shows that during 1991-2003, the United States consumed, on average, 70% of its petroleum as gasoline and middle distillates. This... 

Combustion. The primary reaction carried out in the gas turbine combustion chamber is oxidation of a fuel to release its heat content at constant pressure. Atomized fuel mixed with enough air to form a close-to-stoichiometric mixture is continuously fed into a primary zone. There its heat of formation is released at flame temperatures deterruined by the pressure. The heat content of the fuel is therefore a primary measure of the attainable efficiency of the overall system in terms of fuel consumed per unit of work output. Table 6 fists the net heat content of a number of typical gas turbine fuels. Net rather than gross heat content is a more significant measure because heat of vaporization of the water formed in combustion cannot be recovered in aircraft exhaust. The most desirable gas turbine fuels for use in aircraft, after hydrogen, are hydrocarbons. Fuels that are liquid at normal atmospheric pressure and temperature are the most practical and widely used aircraft fuels kerosene, with a distillation range from 150 to 300 °C, is the best compromise to combine maximum mass —heat content with other desirable properties. For ground turbines, a wide variety of gaseous and heavy fuels are acceptable. 

Consideration of the nature of the petrochemical refinery itself gives some clues as to another source of its profit problem. In the simple, basic unit depicted in Figure 2 thermal cracking dominates the operation. Over 90% of the crude input is consumed without regard to relative values. Thus, it is an indiscriminate cracker of butanes, light naphtha, heavy naphtha, kerosene, distillate, atmospheric gas oil, and vacuum gas oil. Since acceptably similar product slates can be obtained from many of these fractions, it is obvious that the economics suffer when the high valued naphtha and kerosene fractions are thermally cracked. 

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