The purification of crude oil, also known as petroleum refining, involves several steps to separate and convert the crude oil into useful products such as gasoline, diesel, and jet fuel. The process can be divided into the following steps:1. Desalting: Crude oil often contains water, inorganic salts, and suspended solids. The first step in the purification process is to remove these impurities. This is done using a desalter, which is a vessel where crude oil is mixed with water and heated. The salts and solids dissolve in the water, which then separates from the oil due to the difference in density. The desalted crude oil is then sent to the next step.2. Distillation: The desalted crude oil is heated and fed into a distillation column, where it is separated into different components based on their boiling points. The column is designed with a series of trays or packing materials that allow the vapor to rise and the liquid to fall. As the vapor rises, its temperature decreases, and the different components condense at different heights in the column. The condensed liquids are collected as side streams, and the remaining vapor is condensed at the top of the column. The products obtained from this step include light gases, naphtha, kerosene, diesel, and heavy residue.3. Conversion: Some of the heavier fractions obtained from distillation are not suitable for direct use and need to be converted into lighter, more valuable products. This is done using various conversion processes, such as cracking, reforming, and isomerization. Cracking involves breaking down large hydrocarbon molecules into smaller ones using heat, pressure, and catalysts. Fluid catalytic cracking FCC and hydrocracking are common cracking processes. Reforming involves rearranging the molecular structure of hydrocarbons to produce high-octane gasoline components. Isomerization involves converting straight-chain hydrocarbons into branched-chain isomers, which have better combustion properties.4. Treating: The products obtained from distillation and conversion steps may contain impurities such as sulfur, nitrogen, and oxygen compounds. These impurities need to be removed to meet product specifications and environmental regulations. Treating processes include hydrotreating, which uses hydrogen and catalysts to remove sulfur and nitrogen compounds, and sweetening, which removes acidic components using alkaline solutions or solid adsorbents.5. Blending: The final step in the purification process is blending the various product streams to obtain the desired properties and specifications for the final products, such as gasoline, diesel, and jet fuel. This involves mixing different components in the right proportions to achieve the required octane rating, viscosity, and other properties.In summary, the purification of crude oil involves desalting, distillation, conversion, treating, and blending steps. The equipment needed for this process includes desalters, distillation columns, reactors for conversion processes, separators, and storage tanks. Each step is based on principles such as density differences, boiling point differences, catalytic reactions, and chemical treatments to separate and convert the crude oil into useful products.