Straight-run distillation

Selected Diesel Fuel Properties from Different German Co-LTFT-Derived Straight-Run Distillate Fractions and the German Sonder Diesel Kraftstoff (SDK) Specifications of the 1940s... 

The term white distillate is applied to all the refinery streams with a distillation range between approximately 80 and 360°C (175 to 680°F) at atmospheric pressure and with properties similar to the corresponding straight-run distillate from atmospheric crude distillation. Light distillate products (i.e., naphtha, kerosene, jet fuel, diesel fuel, and heating oil) are all manufactured by appropriate blending of white distillate streams. 

The distillate manufacturing processes of diesel fuel oils, such as fuel oil 1-D and fuel oil 2-D, are similar to those of fuel oil no. 1 and fuel oil no. 2, respectively (lARC 1989). Fuel oil no. 1-D is manufactured from a straight-run distillate process. Diesel fuel oil (1-D, 2-D) is defined as the fraction of petroleum that distills after kerosene (Air Force 1989). Fuel oil no. 2-D is also made from mixing of straight-run and catalytically cracked distillates (LARC 1989). 

Gas oils Utilized as straight-run distillate after desulfurization. Lighter atmospheric and vacuum gas oils are often hydrocracked or catalytically cracked to produce gasoline, jet, and diesel fuel fractions heavy vacuum gas oils can be used to produce lubestocks or as fluid catalytic cracking (FCC) feedstock... 

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. 

Today s diesel fuel grades are blends which may contain straight-run distillate, cycle oil, various gas oils, and heavy cracked distillates. Kerosene or jet fuel may be blended into the diesel to improve the low-temperature viscosity and handling characteristics of the fuel. 

Ignition-Quality Improvers. Diesel fuels have found greatly increased use in recent years—so much so that refiners have had to look to cracked distillates from catalytic cracking operations for their extra Diesel fuels. While these cracked distillates have the advantages of relatively high heat content and low pour point, they are inferior in ignition quality (cetane number) to straight-run distillates from the same crudes. 

NAPHTHENIC ACIDS. The term naphthenic acid, as commonly used in the petroleum industry, refers collectively to all of the carboxylic adds present m crude oil. Naphthenic adds are classified as monobasic carboxylic acids of the general formula RCOOH, where R represents the naphthene moiety consisting of cyclopentine and cyclohexane derivatives. Naphthenic adds are composed predominantly of alkyl-substituted cycloaliphatic carboxylic adds, with smaller amounts of acyclic aliphatic (paraffinic or fatty) acids. Aromatic, okfinic. hydroxy, and dibasic acids are considered to be minor components. Commercial naphthenic aads also contain varying amounts of unsaponifiable hydrocarbons, phenolic compounds, sulfur compounds, and water. The complex mixture of adds is derived from straight-run distillates of petroleum, mostly from kerosene and diesel fractions. See also Petroleum. 

Product yields (Table 8-1) indicate that there is no coke. The distillates produced by this process are generally lower in the content of olefin hydrocarbons than the other thermal cracking process, comparatively easy to desulfurize in hydrotreating units, and compatible with straight run distillates. 

The hot separator top product, together with recovered distillates and straight-run distillates enters the gas phase hydrogenation reactor. The gas phase hydrogenation reactor operates at the same pressure as the liquid phase hydrogenation reactor and contains a fixed bed of commercial hydrotreating catalyst. The operation temperature (340-420°C) is controlled by a hydrogen quench. The system operates in a trickle flow mode. The separation of the synthetic crude... 

Gulfining a catalytic hydrogen treating process for cracked and straight-run distillates and fuel oils, to reduce sulfur content improve carbon residue, color, and general stability and effect a slight increase in gravity. 

On the w hole. these analyses show that gas oil steam cracking produces fewer light produas than the treatment of naphtha, and more heavy products which display a higher aromatics content. Hence the Cj- 200 C cut boosts the BTX (Benzene, Toluene, Xylenes) (majority benzene concentration. Similarly, fuel oil (fraction above 200 C) displays a more pronounced aromatic character. This feature makes it incompatible with straight-run distillation fuel oils. The mixture causes the deposition of asphaltenes and other... 

Heavy distillate (straight-run distillate or SRD), containing compounds that boil in the range 205°C to 275°C (400°F to 530°F). This material is hydrotreated to remove sulfur compounds and can then be blended into heating oils and diesel fuels for trucks, railroad engines, and off-road applications such as tractors and mining equipment. 

The gases from straight-run distillation and storage are very rich in heavier hydrocarbons, as shown in Table V. 

Table V. Composition of Gases from Straight-Run Distillation...

Jet fuels consist entirely of hydrocarbons except for trace quantities of sulfur compounds and approved additives. Jet fuels are produced, for example, by blending straight-run distillate components, and olefins are limited by specification (ASTM D-1319, IP 156) or by the bromine number (ASTM D-1159, ASTM D-2710, IP 130). 

In atmospheric or straight-run distillation the crude oil is first pumped into the fractional distillation unit. This is the refinery s tallest unit and some of its columns are used for atmospheric distillation while others are for vacuum distillation. Heated to about 680°F in the gas furnaces, the petroleum reaches the first atmospheric column, which is divided into compartments for fractional distillation. The lighter and more volatile hydrocarbons rise to the upper part. Those that are heavier and less volatile collect in the lower part. While rising, a volatile mass tends to shed its less volatile elements. 

Table III also shows how propylene yield is reduced if ethylene production of a furnace is maximized by increasing severity for a given stock. Examples chosen are n-butane, straight run distillate, and gas oil.

Sulphur dioxide Straight run distillates Burning kerosenes Furfural and alcohols Lube oil feed Lube oil... 

The petroleum industry first obtained gasoline by straight-run distillation. Next the longer molecules were cracked. Now gasoline is being nthesized on a large scale. For this purpose, the most important reaction in all probability is an alkylation wherein olefins, by the aid of catalysts, are made to combine with other molecules such as isoparaffins and aromatics. ... 

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