Also known as: reformable naphtha, heavy straight run naphtha
Heavy naphtha is a distillation cut primarily made up of material roughly the same density as finished gasoline. Heavy naphtha molecules typically have from 7-9 carbon atoms. Its boiling range can be from 180F to 330F.
Most of the heavy naphtha in a refinery comes directly from the atmospheric distillation unit. However, additional volumes may come from the hydrocracker (as heavy hydrocrackate) or from the coker (as coker naphtha).
The heavy naphtha distillation cut is typically sent to the reformer to upgrade its quality to make it suitable as a gasoline blendstock. Heavy naphtha can also be blended directly into gasoline, but its low octane makes this undesirable.
Most of th naphtha sent to the reformer must first be hydrotreated to remove impurities that are harmful to the reformer catalyst. The exception is naphtha from a hydrocracker, which is essentially already hydroteated.
Refiners can adjust the cut points of heavy naphtha to shift volume into light naphtha and/or kerosene, and to reduce the volume going to the reformer. Shifting the heavier end of the heavy naphtha into kerosene allows a refiner to increase kerosene and diesel yield, but at the cost of lowering the flash point of the kerosene.