Distillation benzene-toluene data

Figure 8-26. Equilibrium curve benzene-toluene for Example 8-10 (curve data only). Used by permission, Robinson, C. S. R. and Gilliland, E. R., Elements of Fractional Distillation, 4th Ed. McGraw-Hill Book Co. (1950), all rights reserved.

For application to distillation (a nearly isobaric process) binary-mixture data are frequently plotted, for a fixed pressure, as y versus x, with a line of 45° slope included for reference, and as T versus y and X, as shown in Figs. 13-3 to 13-8. In some binary systems, one of the components is more volatile than the other over the entire composition range. This is the case in Figs. 13-3 and 13-4 for the benzene-toluene system at pressures of both 101.3 and 202.6 kPa (1 and 2 atm), where benzene is more volatile than toluene. 

A feed stream made up of 40% mole benzene and 60% mole toluene is to be separated into benzene-rich and toluene-rich products using a distillation column. The column has ten equilibrium stages including a partial condenser and a partial reboiler and is operated at 172 kPa. The feed stream, with a flow rate of 100 kmol/h, is at its bubble point at 172 kPa and is placed in the fourth stage from the top. It is required to determine the compositions of the two products at different reflux ratios. Vapor-liquid equilibrium data for the benzene-toluene system are provided in Table 5.1 at 172 kPa. 

Although pure hydrocarbons such as pentane, hexane, heptane, benzene, toluene, and xylene, which are now largely of petroleum origin, may be characterized by a fixed boiling point, naphtha is a mixture of many hydrocarbons and cannot be so identified. The distillation test does, however, give a useful indication of their volatility. The data obtained should include the initial and final temperatures of distillation together with sufficient temperature and volume observations to permit a characteristic distillation curve to be drawn. 

The actual variations in the V and L streams in a distillation column depend on the enthalpies of the vapor and liquid mixtures. The limitations imposed by assuming constant molal overflow can be removed by enthalpy balances used in conjunction with material balances and phase equilibria. The enthalpy data may be available from an enthalpy-concentration diagram, such as the one in Fig. 18.24. Since benzene-toluene solutions are ideal, this diagram was constructed using molar average heat capacities and heats of vaporization. Some... 

Using Fig. 1.17 with data from Appendix I, plot logo (relative volatility) of C5 to C12 normal paraffins as referred to n-Cs against the carbon number (5 to 12) at a reasonable temperature and pressure. On the same plot show log a for Cs to Cio aromatics (benzene, toluene, ethylbenzene, etc.), also with reference to n-Cs. What separations are possible by ordinary distillation, assuming a mixture of normal paraffins and aromatic compounds (E. D. Oliver, Diffusional Separation Processes Theory, Design Evaluation, J. Wiley Sons, New York, 1966, Chapter 13. 

Properties Wh. needle-like crystals odorless sol. in alcohol, benzene, toluene, chloroform, DMF, most org. soivs. sparingly sol. in water m.w. 119.12 m.p. 98.5 C b.p. 204 (15 mm) flash pt. > HOC may explode during vacuum distillation Toxicoiogy LD50 (oral, rat) 600 mg/kg, (IP, mouse) 400 mg/kg, (IV, mouse) 238 mg/kg poison by IV route mod. toxic by ing., IP routes cyanosis questionable carcinogen experimental tumorigen mutagenic data TSCA listed... 

The numerical methods were tested by means of two examples delivered with the chemical process simulator SPEEDUP [1, 6]. The example DYNEVAP consisting of 87 equations within 13 subsystems represents a double effect evaporator. The second example BTX, a mathematical model of a Benzene-Toluene-Xylene distillation column, is made of 52 subsystems containing 1089 equations. It has been written a code which is able to create automatically an interface for our codes out of the data supplied by SPEEDUP when simulating a process. The interface contains the DAE system in a structured representation. It is used for subsystem-wise function and Jacobian matrix evaluation. 

On the other hand, distillation involves the interaction of a system where a number of temperatures are involved. Data for a binary system (benzene-toluene) is shown in Figure 12-3 in the form of a boiling point diagram. This form can be converted to a plot of mole fraction of the more volatile in the vapor versus mole fraction of die more volatile in the liquid (Figure 12-4). 

Fig. 111.—Experimental values of the interaction parameter %i plotted against the volume fraction of polymer. Data for polydi-methylsiloxane M =3850) in benzene, A (New-ingi6). polystyrene in methyl ethyl ketone, (Bawn et aV ) and polystyrene in toluene, O (Bawn et alP) are based on vapor pressure measurements. Those for rubber in benzene, T (Gee and Orr ) were obtained using vapor pressure measurements at higher concentrations and isothermal distillation equilibration with solutions of known activities in the dilute range.

An equimolar mixture of benzene and toluene is subjected to flash distillation at 100 kN/m2 in the separator. Using the equilibrium data given in Figure 11.9, determine the composition of the liquid... 

Many azeotropic combinations exist among hydrocarbons themselves. Aromatic hydrocarbons, for example, are almost always found in petroleum fractions distilling below the true boiling point of the aromatics. Marschner and Cropper (41) accurately delineated the limits of azeotropy for benzene and toluene with saturated hydrocarbons, and Denyer et al. (11) did the same for the thiols. Consideration of such data is desirable in the design and operation of equipment for the distillation of gasoline fractions to produce specialized products. 

Figure 13.29. Composition profiles and flowsketches of two azeotropic distillation processes (adapted by King, 1980). (a) Separation of ethanol and water with benzene as entrainer. Data of the composition profiles in the first column were calculated by Robinson and Gilliland, (1950) the flowsketch is after Zdonik and Woodfield (in Chemical Engineers Handbook, McGraw-Hill, New York, 1950, p. 652). (b) Separation of n-heptane and toluene with methylethylketone entrainer which is introduced in this case at two points in the column (data calculated by Smith, 1963).

Axial flow pumps, 134, 136, 140 applicafion range, 150 Azeotrope separation, 387,388,420-426 Azeotropic distillation, 420-426 acetonitrile/water separation, 422 commercial examples, 421-424 design method, 424 ethanol/water/benzene process, 424 n-heptane/toluene/MEK process, 424 vapor-liquid equilibrium data, 421, 423, 425,426... 

Solve Problem 6.8 graphically or analytically with the column having two feed streams Stream 1, 80 kmol/h, 50% mole benzene, and 50% mole toluene, saturated liquid, sent to stage 3 Stream 2, 20 kmol/h, 30% mole benzene, and 70% mole toluene, saturated vapor, sent to stage 5. Use any other necessary data as given in Problem 6.8, and find the product compositions at a reflux ratio of 2 and a distillate rate of 50 kmol/h. 

An equimolai mixture of benzene and toluene is to be distilled in a plate column at atmospheric pressure. The feed, saturated vapor, is to be fed to the optimum plate. The distillate is to contain 98mole% benzene, while the bottoms is to contain 2 mole% benzene. Using the Ponchon method and data below [Ind. Eng. Chem., 39, 752 (1947)], calculate ... 

We plan to study the distillation of the ideal system A = benzene, B = toluene, and C = cumene by generating total reflux distillation curves and residue curves. The equilibrium data for this system can... 

Benzene, styrene, toluene, and xylene are to be separated with the array of distillation columns shown in Figure 3.4. Experimental data show that the feed rate (stream A) is 100 mole/hr and that the composition of stream A is 10% benzene, 15% styrene, 35% toluene and 40% xylene (compositions are in mole %). 

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