An oil refinery is a complex of industrial units that work together to convert crude oil into valuable products such as gasoline, diesel, kerosene, jet fuel, liquefied petroleum gas (LPG), and bitumen. Each unit performs a specific function, and the product generated in one unit is typically used as the feedstock for the next. Understanding these units provides a clearer insight into the refining process and how various petroleum products are produced.
Atmospheric Distillation Unit: The Heart of the Refinery
The Atmospheric Distillation Unit (ADU) is the first and most important section of every oil refinery. In this unit, crude oil is heated before entering the distillation column, where its components are separated according to their different boiling points.
In this process, products such as liquefied petroleum gas (LPG), naphtha, kerosene, diesel, and fuel oil are produced. In fact, all downstream refinery units receive their feedstock from this section, which is why it is commonly referred to as the heart of the refinery.
Vacuum Distillation Unit
The heavy residue from the atmospheric distillation column still contains valuable hydrocarbon components that cannot be separated under normal atmospheric pressure. These materials are sent to the Vacuum Distillation Unit (VDU), where they are separated under reduced pressure without undergoing thermal decomposition.
The products of this unit include Vacuum Gas Oil (VGO), base oils, and vacuum residue (vacuum bottom), which are used in the production of bitumen, industrial lubricants, and as feedstock for conversion units.
Cracking Unit
One of the most important sections of a refinery is the Cracking Unit. In this unit, heavy hydrocarbon molecules are converted into lighter and more valuable compounds.
The main goal of this process is to increase the production of gasoline, diesel, and other light petroleum products. Today, most refineries use Fluid Catalytic Cracking (FCC) units, which provide higher conversion efficiency and better product quality compared to traditional methods.
The products of this unit include Vacuum Gas Oil (VGO), base oils, and vacuum residue (vacuum bottom), which are used in the production of bitumen, industrial lubricants, and as feedstock for conversion units.
Hydrotreating Unit
Petroleum products usually contain sulfur, nitrogen, and other impurities that can cause environmental pollution or damage equipment. In the Hydrotreating Unit, these impurities are removed using hydrogen and catalysts.
The products obtained from this unit have higher quality and are more compatible with modern environmental standards.
The products of this unit include Vacuum Gas Oil (VGO), base oils, and vacuum residue (vacuum bottom), which are used in the production of bitumen, industrial lubricants, and as feedstock for conversion units.
Catalytic Reforming Unit
The Catalytic Reforming Unit is responsible for improving the quality of naphtha and producing high-octane gasoline. In this process, the structure of hydrocarbon molecules is modified, producing compounds that enhance fuel performance in gasoline engines.
Another advantage of this unit is the production of hydrogen, which is used in other refinery units, particularly in hydrotreating processes.
محصولات خروجی این واحد کیفیت بالاتری دارند و با استانداردهای زیستمحیطی روز دنیا سازگارتر هستند.
The products of this unit include Vacuum Gas Oil (VGO), base oils, and vacuum residue (vacuum bottom), which are used in the production of bitumen, industrial lubricants, and as feedstock for conversion units.
Isomerization Unit
In this unit, hydrocarbon molecules undergo structural rearrangement without changing the number of atoms. This structural modification increases the octane number of gasoline and improves fuel quality.
The Isomerization Unit is considered one of the key sections of modern refineries, as it enables the production of high-quality gasoline without increasing pollutant emissions.
Sulfur Recovery Unit
During the refining process, a significant amount of sulfur is removed from crude oil and natural gas. If this sulfur is released into the environment, it can cause severe pollution.
During the refining process, a significant amount of sulfur is removed from crude oil and natural gas. If this sulfur is released into the environment, it can cause severe pollution.
واحد تولید قیر و روغن پایه
Some refineries have dedicated units for the production of bitumen and base oils. In the bitumen production unit, vacuum residue (vacuum bottom) is converted into various types of paving and industrial bitumen. Additionally, in the base oil production unit, refined oil fractions are processed and converted into raw materials used for manufacturing various lubricants and engine oils.
The presence of these units increases the added value of the refinery and enhances the diversity of its manufactured products.
Conclusion
An oil refinery consists of a set of specialized units, each of which plays an important role in converting crude oil into usable products. Units such as atmospheric distillation, vacuum distillation, cracking, hydrotreating, reforming, sulfur recovery, and bitumen production form an integrated chain that results in the production of fuels and products required by various industries. Understanding the function of these units shows that oil refining is not a simple process, but rather a combination of advanced and interconnected technologies that play a significant role in energy supply and industrial development.
The presence of these units increases the refinery’s added value and diversifies its range of produced products.
