Distillation operating diagrams

A more complex unit is shown in Fig. 13-24, which is a schematic diagram of a distillation column with one feed, a total condenser, and a partial reboiler. Dotted hnes encircle the six connected elements (or units) that constitute the distillation operation. The variables N, that must be considered in the analysis of the entire process are just the sum of the Nfs for these six elements since here Nr = 0. Using Table 13-5,... 

Residue cui ve maps and distillation region diagrams are very power-Ril tools for understanding all types of catch and continuous distillation operations, particularly when combined with other information such as hquid-liqiiid binod cui ves. Applications include ... 

The transformed variables describe the system composition with or without reaction and sum to unity as do Xi and yi. The condition for azeotropy becomes X, = Y,. Barbosa and Doherty have shown that phase and distillation diagrams constructed using the transformed composition coordinates have the same properties as phase and distillation region diagrams for nonreactive systems and similarly can be used to assist in design feasibility and operability studies [Chem Eng Sci, 43, 529, 1523, and 2377 (1988a,b,c)]. A residue curve map in transformed coordinates for the reactive system methanol-acetic acid-methyl acetate-water is shown in Fig. 13-76. Note that the nonreactive azeotrope between water and methyl acetate has disappeared, while the methyl acetate-methanol azeotrope remains intact. Only... 

Composition and temperature profiles are shown in Figures 14.13 and 14.14. In this example we see that the vapor and liquid temperatures are rather different. This result is quite typical of absorption columns indeed, it is possible for temperature differences to be over the order of 20 K. The McCabe-Thiele diagram is shown in Figure 14.15 and the component efficiencies in Figure 14.16. The efficiencies tend to be lower than in the distillation operations considered above. 

Figure 14.19. Schematic diagram of extractive distillation operation.

Describe what is represented in an operating diagram. What is the meaning of an operating line or curve How many operating lines are required in crosscurrent cascades, and how many in a counter-current operation What are the requirements for fractional distillation ... 

Complete graphical representation of the equilibria requires a three-dimensional diagram [29, 47], as in Fig. 9.1. The curve marked is the vapor-pressure curve of A, lying entirely in the nearest composition plane at x = 1.0. The curve extends from its critical point to its triple point 7 a. but the complications of the solid phase which do not enter into distillation operations will not be considered. Similarly curve is the vapor pressure of pure B, in the far plane at X = 0. The liquid and vapor regions at compositions between x = 0 and 1,0 are separated by a double surface which extends smoothly from p to pg. The shape of this double surface is most readily studied by considering sections at constant pressure and constant temperature, examples of which are shown in the figure. 

Processes involving oxygen and nitrogen oxides as catalysts have been operated commercially using either vapor- or Hquid-phase reactors. The vapor-phase reactors require particularly close control because of the wide explosive limit of dimethyl sulfide in oxygen (1—83.5 vol %) plants in operation use Hquid-phase reactions. Figure 2 is a schematic diagram for the Hquid-phase process. The product stream from the reactor is neutralized with aqueous caustic and is vacuum-evaporated, and the DMSO is dried in a distillation column to obtain the product. 

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