Distillation nomograph

The resulting nomograph, relating component recovery and component relative volatility, is given in Figure 8-51. This may be used to estimate component recovery in distillate and bottoms, as follows ... 

You ve found all the leaks and the pressure in your vacuum distillation setup is, say, 25 torr. Now you need to know the boiling point of your compound, 1-octanol, this time at 25 torr and not 760 torr. You realize it ll boil at a lower temperature, but just how low The handy nomographs in (Figs. 76 and 77) can help you estimate the new boiling point. 

Many compounds decompose when heated to their boiling points so they cannot be distilled at atmospheric pressure. In this situation it may be possible to avoid thermal decomposition by carrying out the distillation at reduced pressure. The reduction in the boiling point will depend on the eduction in pressure and it can be estimated from a pressure-temperature nomograph (Fig. 11.11). 

A linear equation method and a nomograph method can be used for estimating vapor-liquid equilibria of gasoline from vapor pressure and distillation test results (ASTM D-4814). However, these estimation methods are not applicable to gasoline-oxygenate blends. 

One of the most widely used methods is based on the calculated cetane index formula. This formula represents a method for estimating the cetane number of distillate fuels from API gravity and mid-boiling point. The index value as computed from the formula is designated as a calculated cetane index (ASTM D-976, IP 218). Because the formula is complicated in its manipulation, a nomograph based on the equation has been developed for its solution. 

Table 6-1, p. 58, shows the m-nitrotoluene has boiling points of 231.9 "C at 760 torr and 130.7 C at 40 torr (5.3 kPa). At what temperature does your nomograph say it should boil when it is distilled at 40 torr ... 

Figure 7-2. Nomograph to determine the rate of molecular distillation.

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