Crude oil vacuum distillation

A modern refinery is a complicated collection of conversion processes, each tailored to the properties of the feed it has to convert. The scheme shown in Fig. 9.1 summarizes the most important operations some reasons for these processes are given in Tab. 9.2, along with relevant catalysts. First the crude oil is distilled to separate it into fractions, varying from gases, liquids (naphtha, kerosene and gas oil), to the heavy residue (the so-called bottom of the barrel ) that remains after vacuum distillation. 

Figure 3.13. Crude oil vacuum tower. Pumparound reflux is provided at three lower positions as well as at the top, with the object of optimizing the diameter of the tower. Cooling of the side streams is part of the heat recovery system of the entire crude oil distillation plant. The cooling water and the steam for stripping and to the vacuum ejector are on hand control.

Crude oil is distilled in a distillation column operating near to atmospheric pressure to produce naphtha (b.p. 30°C - 180°C) and gas oil (b.p. 25°C - 360°C). The bottoms of the column, known as atmospheric residua, are passed to a vacuum distillation column which produces vacuum gas oil (b.p. 350°C - 550 C). Any of these distilled liquid feeds can be used to produce petrochemicals. 

Pyrolysis of Shale Oil Crude and Vacuum Distillate Fractions... 

Birgenheier, D.B. and Wetzel, L. (1988) Design of Vacuum Systems for Crude Oil Vacuum Tower Distillation, Hydrocarbon Processing Symposium. Available at http //www.graham-mfg.com/usr/pdf/TechLibVacuum/22.PDF. 

The fitting capability of the 25 selected functions was done using two distillation data sources those previously reported in the literature (Sanchez et al., 2007, and references therein) and data obtained in laboratories at the Mexican Institute of Petroleum and University of Alberta. The selected samples include whole crude oils, vacuum gas oils, atmospheric and vacuum residua, atmospheric gas oils, light cycle oils (LCO),... 

Vacuum distillation of the atmospheric residue complements primary distillation, enabli r.ecoyery of heavy distillate cuts from atmospheric residue that will un r o further conversion or will serve as lube oil bases. The vacuum residue containing most of the crude contaminants (metals, salts, sediments, sulfur, nitrogen, asphaltenes, Conradson carbon, etc.) is used in asphalt manufacture, for heavy fuel-oil, or for feed for others conversion processes. 

Properly speaking, steam cracking is not a refining process. A key petrochemical process, it has the purpose of producing ethylene, propylene, butadiene, butenes and aromatics (BTX) mainly from light fractions of crude oil (LPG, naphthas), but also from heavy fractions hydrotreated or not (paraffinic vacuum distillates, residue from hydrocracking HOC). 

Feedstocks are light vacuum distillates and/or heavy ends from crude distillation or heavy vacuum distillates from other conversion processes visbreaking, coking, hydroconversion of atmospheric and vacuum residues, as well as deasphalted oils. 

The suspension of phenylacetamide may be further hydrolysed to phenylacetic acid by refluxing with stirring until the solid dissolves. The mixture becomes turbid after 30 minutes and the product begins to separate as an oil refluxing is continued for 6 hours, the mixture is cooled first with tap water and then by an ice-water bath for about 4 hours. The crude phenylacetic acid is filtered at the pump, washed with two 50 ml. portions of cold water, and dried in a desiccator. The resulting crude acid melts at 69- 70° it may be purified by recrystallisation from light p>etroleum (b.p. 40-60°) or, better, by vacuum distillation. 

You know how just a couple of paragraphs ago where the chemist first filtered the crude crystals from the chilled reaction mixture, then washed them with water or acetic acid Well, all that liquid filtrate has a lot of valuable, unreacted piperonal or benzaldehyde in it. To rescue the stuff the chemist dilutes the mixture with 500ml dHaO and extracts it with DCM. The DCM is washed with 100ml 5% NaOH solution then vacuum distilled to give a dark oil which is unreacted aldehyde. Hey That s a lot of good material that can be put through the process again. 

After dilution with 200 ml. of benzene, the solution is transferred to a 2-1. separatory funnel containing 800 ml. of ice water and shaken thoroughly. The aqueous layer is separated, acidified to pH 3-4 with 2-3 ml. of concentrated hydrochloric acid, and extracted with three 100-ml. portions of benzene. All the organic layers are then combined and dried over anhydrous sodium sulfate. Filtration and concentration of the solution with a rotary evaporator, followed by exposure to high vacuum for 2-3 hours, affords 17.3-19.3 g. of the crude product (Note 3). Low-boiling impurities are removed by vacuum distillation (Note 4), the residual oil (14-15 g.) is transferred to a 50-ml. flask equipped with a short-path distillation apparatus, and vacuum distillation is continued. A forerun is taken until no rise in boiling point is observed, and then 7.2-8.6 g. (23-27%) of dimethyl nitrosuccinate is collected as a colorless oil, b.p. 85° (0.07 mm.), 1.4441 (Note 5). 

One of the most important operations in a refinery is the initial distillation of the crude oil into its various boiling point fractions. Distillation involves the heating, vaporization, fractionation, condensation, and cooling of feedstocks. This subsection discusses the atmospheric and vacuum distillation processes which when used in sequence result in lower costs and higher efficiencies. This subsection also discusses the important first step of desalting the crude oil prior to distillation. 

The atmospheric reduced crude is the feedstock for the vacuum distillation unit. To prevent thermal decomposition (cracking) of the higher boiling point hydrocarbons in the crude oil, the pressure in the vacuum distillation fractionation column is reduced to about one-twentieth of an atmosphere absolute (one atmosphere pressure is 14.7 psia or 760 mm Fig). This effectively reduces the boiling points of the hydrocarbons several hundred degrees Fahrenheit. The components boiling below about 1050°F (565°C) are vaporized and removed as vacuum gas... 

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