ABSTRACT
C7+ fractions: It is common to see some defined C7 −C10 components quantitatively analyzed for, but a complete component analysis of the C7+ fraction will not be doable. The number of components is simply too high. Instead the C7+ fraction is split into carbon number fractions, each of which contains hydrocarbons with boiling points within a given temperature interval. The temperature intervals may be seen from Table 2.1 and are determined by the boiling points of the n-paraffins. If a true boiling point (TBP) analysis as presented in Chapter 2 has been carried out, measured densities at standard conditions (atmospheric pressure and 15°C) and measured molecular weights will also be available for each C7+ fraction. When characterizing a C7+ fraction, it is essential to take into consideration the diversity of hydrocarbon components contained in the fraction. Figure 5.2 shows four different components belonging to the C9 fraction. The importance of structural differences for the phase behavior is illustrated in Figure 5.3. The dew point of a binary mixture of C1 and C9 is seen to depend heavily on the chemical structure of the C9 component. The maximum dew point temperature is around 20°C higher when C9 is nC9 than when it is dimethylcyclohexane.
