True boiling-point distillation

It has also been proposed to classify heavy oils according to characterization gravity. This is defined as the arithmetic average of the instantaneous specific gravity of the distillates boiling at 177°C (350°F), 232°C (450°F), and 288°C (550°F) vapor line temperature at 25 mm pressure in a true boiling-point distillation. 

Fifteen/Five (15/5) Distillation A laboratory distillation which is also referred to as the true boiling point distillation. It is performed on a column containing 15 theoretical plates at a reflux ratio of 5 1. 

Figure 1. True boiling point distillations for Illinois H-coal, Wyodak H-coal, and SRC-II syncrudes...

Figure 1. Simulated true boiling point distillations for SRC-II, Illinois H-coal, and Wyodak H-coal whole process products...

When complex multicomponent mixtures are distilled, particularly those associated with oil refining, it is difficult to characterize them in terms of their components. Instead, they are characterized in terms of their boiling range, which gives some indication of the quantities of the components present. The true boiling point distillation (TBP) is probably the most useful, in which the percent distilled is recorded as a function of the boiling temperature of the mixture. For the TPB distillation, a 5 1 reflux ratio is often used with 15 theoretical stages in a laboratory characterization column (see Section III). 

FIG. 13-83 Variation of boiling temperature with percent distilled in true-boiling-point distillation of light hydrocarbons. 

FIG. 13-85 Average true-boiling-point distillation curves of crude oils. From W. E. Edmister, Applied Hydrocarbon Thermodynamics, vol. 1, 1st ed., 1961 Gulf Publishing Company, Houston, Texas, Used with permission. All rights reserved.)... 

Geddes, R.L. Computation of petroleum fractionation—estimation of A.S.T.M. distillation curves from true boiling-point distillation analyses. Ind. Eng. Chem. 1941, 33, 795-801. 

In many cases distribution functions are determined experimentally the characterization of petroleum fractions by true-boiling-point distillation or gas-chromatographically simulated distillation, and the characterization of polymers by gel-permeation chromatography. In principle, the integrals of continuous thermodynamics may be directly solved based on these experimentally determined distribution functions. However, this approach delicate numerical analyses and the assumption the complete distribution function has been obtained by experiment clearly this is no the case, for example, for some polymers only molar-mass averages are determined. Thus, there are numerous cases where smoothed or analytical distribution function provides more reliable phase equilibrium calculation than those obtained by use of the experimentally determined distribution function. When the integrals of continuous thermodynamics possess analytical solutions considerably numerical simplification is afforded and this is one motive for the desire to have analytical expressions for the distribution function. 

Eggersfon el al. (69) in 1960 firsl reported that low-resolution, temperature-programmed, gas chromatographic data could be used to simulate the more time-consuming true-boiling-point distillation. Retention times were correlated... 

If the distillate during a true-boiling-point distillation were to be divided into two fractions at some convenient point. A, corresponding to the temperature h, and rimple distillation and true-boiling-point curves obtained for the two fractions, the results would resemble the... 

Relative Bias—There exists a bias between the empirical results of distillation properties obtained by this test method and the true boiling point distillation curve obtained by Test Method D 2892. The amount of relative bias between the two test methods has not been determined. 

Fio. 4-3. Average true-boiling-point distillation curves of crude oils. 

Tnie-boiling-point Apparatus. This equipment is used to obtain a so-called true-boiling-point distillation curve (see Figs. 4-3 and 4-9). An equipment that accomplishes a good degree of fractionation is termi d true-boiling-point equipment. 

Boiling points taken from a true-boiling-point distillation are additive, and vapor pressures when based on molal percentages are additive (Raoult s law). Common additive properties are specific gravity, aniline point, per cent sulfur, hydrogen-carbon ratio, etc. However, since any... 

The evaluation of a paraffin-base crude oil is particularly simple because the oil contains no asphalt. Only a true-boiling-point distillation, con-... 

Fio. 16-21. True-boiling-point distillation curves of gasolines produced in a four-plate tower using various reflux ratios. Note the curve for infinite reflux and infinite plates. Oil Gas J.)... 

The approximate condensation and true-boiling>point distillation curves of the products are shown in Fig. 17-16, and a diagram of the system is shown in Fig. 17-17. nce this example is aimed at an illustration of principles, the molecular weights, specific heats, and latent heats have not been corrected to the latest values shown in this edition. 

The gasification model was applied to four vacuum residua with boiling range higher than 538°C+ (1000°F+), obtained by TBP (true boiling point) distillation of various crude oils ... 

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