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Petroleum refining

A petroleum refining plant is an industrial complex where the crude oil is processed and developed into various more helpful petroleum products such as liquefied petroleum gas, kerosene, heating oil, asphalt base, diesel fuel and gasoline.

A major component of the petroleum refining process is the fractional distillation of the crude oil. This distillation process works because the different hydrocarbon compounds have different boiling points, depending upon the length and size of the compounds. By heating the crude oil, to 400 degrees C, paraffin wax, asphalt and lubricating oil are boiled off and that fraction is removed via pipes to another part of the petroleum refining plant. Next to go is fuel oil. As the product cools to about 370 degrees C and condenses, it is also drawn off. With still more cooling to approximately 300 degrees C diesel is removed from the mix. At 200 degrees C kerosene is recoverable. Gasoline condenses at approximately 150 degrees C and the most volatile gases at 20C are drawn out of the process.

Each of the products of the initial distillation process is important and is used for other of the many petroleum-refining products available. Hydrocarbons can be remodeled in so many different ways because the hydrocarbons form in many strengths, weights and lengths of molecules. Once the hydrocarbons are split apart and purified of impurities, they can be sold as is without further processing. The small hydrocarbons can be recombined and added back to gasoline and other fuel products in order to make them function better. By mixing and matching smaller molecules which may also have been processed through combining, cracking or stripping hydrogen from the hydrocarbon molecules, a specific octane can be prepared to meet specific requirements for the fuel.

Because petroleum refining plants are such large scale operations, they are typically operated constantly rather than in batches and may be in operation for months or even years. The investment to construct and operate such a plant makes it imperative that it will be operational for a very long period of time.

At least ten products are routinely produced in a petroleum refining plant, where they may be shipped in tanker trucks or ships, or via pipeline to the end site or to yet another manufacturing process. These products include asphalt, diesel fuel, naphtha, fuel oils, gasoline, kerosene, liquid petroleum gas (LPG), lubricating oils, paraffin wax and tar. Each of these products comes from different levels of the fractional tower

In addition, specialty end products recover even more profit from the process of refining. The sulphur which is removed from the gasoline is sold as sulfur or sulfuric acid. Paraffin wax becomes the coating on frozen food product packages. Asphalt tar is sold in bulk for tar and gravel roof coating.

Health and safety issues have been brought to the forefront in the petroleum refining industry to the point where no new plants have been built in the United States since 1976, although many plants have been expanded during the period.