A refinery is basically a system of high complexity with numerous interrelalted flows, processing units and operations. The basic aim of any refinery is to separate crude petroleum into its various components, and to sell these end products in the market for revenue. Any refinery process can be summed up as follows: 

The crude oil is heated in a furnace and charged to an atmospheric distillation tower, where it is separated into lighter components viz; butanes, lighter wet gas, unstabilized light naphtha, heavy naphtha, kerosene, atmospheric gas oil and topped (reduced) crude (ARC).

The topped crude is sent to the vacuum distillation unit and separated into vacuum gas oil stream and vacuum reduced crude bottoms (residua, resid or VRC).

These are then cracked thermally in a delayed coker to produce wet gas, coker gasoline, coker gas oil, and coke. Historically the heavy bottoms have sold for about 70% of the price of crude oil."- Petroleum refining (Gary & Handwerk)

A lot of the terms above, which may now seem unfamiliar will be discussed in detail as we go on. The largest consumer of petroleum products is the transportation sector. Hence all refineries ultimatley aim for conversion of the basic feed stock into transportation fuel through economically viable methods.

The crude oil obtained from every region of the world (including different regions within the same country)  are different in their physical and chemical composition.

 Thus the key to understanding any refinery and its related processes begins with learning to categorize and recognize the crudes that are fed into them, inorder to undersatnd what subsequent operations can be performed on them and what output they might yield. 

Click on a link below to continue