Defined distillation fractions

Define recrystallization, distillation, fractional distillation, extraction, liquid-liquid extraction, solvent extraction, countercurrent distribution, liquid-solid extraction, and chromatography. 

We fractionated CCB by a high vacuum distillation into several distillate fractions and undistlllable residue. The distillate fractions were subjected to a two-stage high temperature thermal process to convert them to aromatic pitches. The composition of the pitches produced was determined by a solvent analysis to define their suitability for synthetic carbon production. 

A typical record obtained for the separation of a mixture of alcohols by this method is shown in Fig. 4-10, and an idealized portion of the curve is shown in Fig. 4-11. The first curve indicates the remarkable efficiency of this method for separating compounds. A quantity equivalent to the theoretical plate previously defined for fractional distillation may be determined with these columns. A triangle is drawn whose sides are tangents to the sides of the peak corresponding to the... 

The test method details procedures for the production of a liquified gas, distillate fractions and residuum of standardized quality on which analytical data can be obtained, and the determination of yields of the above fractions by both mass and volume. From the above information a graph of temperature versus mass-percent distilled can be produced. This distillation curve corresponds to a laboratory technique which is defined at 15/5 (15 theoretical plate column, 5 1 reflux ratio) or TBP (true boiling point). 

Next the crude is distilled into well defined fractions according to their end uses. 

Reflux ratio. This is defined as the ratio between the number of moles of vapour returned as refluxed liquid to the fractionating column and the number of moles of final product (collected as distillate), both per unit time. The reflux ratio should be varied according to the difficulty of fractionation, rather than be maintained constant a high efficiency of separation requires a liigh reflux ratio. ... 

For distillations, it is often of more interest to ascertain the effect of entrainment on efficiency than to predic t the quantitative amount of liquid entrained. For this purpose, the correlation shown in Fig. 14-26 is useful. The parametric curves in the figure represent approach to the entrainment flood point as measured or as predicted by Fig. 14-25 or some other flood correlation. The abscissa values are those of the flow parameter discussed earher. The ordinate values y are fractions of gross hquid downflow, defined as follows ... 

The identification of geraniol can be confirmed by its conversion into citral, Cj Hj O, its aldehyde, which has a very characteristic odour and yields well-defined crystalline derivatives. Five parts of the alcohol fraction are shaken with 2-5 parts of chromic acid and four parts of concentrated sulphuric acid dissolved in 100 parts of water. The mixture is warmed in the water-bath for a few minutes, when crude citral separates on the surface of the liquid. This is purified by steam distillation and conversion into its sulphonic acid compound in the... 

The teed to the cat cracker in a typical refinery is a blend of gas oils from such operating units as the crude, vacuum, solvent deasphalting, and coker. Some refiners purchase outside FCC feedstocks to keep the FCC feed rate maximized. Other refiners process atmospheric or vacuum residue in their cat crackers. In recent years, the trend has been toward heavier gas oils and residue. Residue is most commonly defined as the fraction of feed that boils above 1,050°F (565 C). Each FCC feed stream has different distillation characteristics. 

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