Generic Process Schematic - petro plant

This image get from http://www.processengr.com/ 

CDU Process:  Distill and separate valuable distillates (naphtha, kerosene, diesel) and atmospheric gas oil (AGO) from the crude feedstock.

The atmospheric residue (AR) with high boiling point  above 350oC (623K) was chosen can be subjected to several treatments, i.e., deasphalting, hydroprocessing and vacuum distillation.

Products of the vacuum distillation are vacuum residue (VR) and VGO.

VR can be deasphalted to produce DAO and asphalt or directly hydroprocessed.

The VGO is usually used as the feed for production of light and/or middle distillates either via hydroprocessing (hydrocracking) or via catalytic cracking.

The FCC and coking of heavy feeds form an integral part of many petroleum refineries. Virgin VGOs, as well as pretreated DAOs and HGOs have been typical feeds for the former process. However, after modifications of the conventional cracking units, RFCC process may also be able to handle the unpretreated DAO and ARs derived from sweet crudes. Hydroprocessing is the process of choice for heavier ARs and VRs, as well as topped heavy crudes.

The asphalt and coke, as the final refinery residues, have an impact on the overall performance of petroleum refineries.

(Reference from ebook: Catalysts for Upgrading Heavy Petroleum Feeds, chapter 2 )