There are usually two naphtha cuts produced from most crude. These are:
- Light naphtha (sometimes called light gasoline)
- Heavy naphtha.
Both these streams are the bottom product of the debutanizer unit. They are separated in a naphtha splitter fractionation tower. The light naphtha contains most of the crude’s C5’s and much of the paraffin portion of the crude’s C6’s. The purpose of making such a division is to produce a satisfactory heavy naphtha which will contain the heavier naphthenes and will be a suitable feed for a catalytic reformer.
The light naphtha has a TBP distillation range of C5 to around 190?F. The heavy naphtha as the feed to the catalytic reformer and is a cut on crude of about 190?–360?F. This cut point of 360?F can vary depending on the severity operation of the catalytic reformer, the volatility specification of the finished gasoline which the reformate will be a major precursor, and the refineries production requirements. In this latter case for example the refinery’s operating plan may call for maximizing kerosene in which case the atmospheric distillation unit would be operated to decrease the amount of overhead distillate in order to increase the kerosene (top side stream) fraction. Of course if the refinery plan is to maximize gasoline the atmospheric tower would be operated to increase the overhead distillate at the expense of the Kero fraction.