CRUDE OIL REFINING

Crude oil, also called petroleum, is a complex mixture of carbon and hydrogen (hydrocarbons), which exist as a liquid in the earth’s crust. Crude oil has many compositions, some is black, thick and tar like, while other crude oils are lighter in color and thinner. The carbon and hydrogen in crude oil are through to have originated from the remains of microscopic marine organisms that were deposited at the bottom of seas and oceans and was transformed at high temperature and pressure into crude oil and natural gas.

This oil and gas migrates upward through the porous rock, as it is less dense than the water which fills the pores. The oil and gas is trapped by a layer of impermeable rock through which they can’t flow. Several different types of oil and gas “traps” exist; a common dome formed by folded sedimentary rocks. Crude oil is obtained by drilling a hole into the reservoir rock (sandstone, limestone etc.) and pumping it out.

Although all fractions of petroleum find uses, the greatest demand is for gasoline. One barrel of crude petroleum contains only 25-35% gasoline. Transportation demands require that over 50% of the crude oil be converted into gasoline. To meet this demand some petroleum fractions must be converted to gasoline. This may be done by “cracking” – breaking down large molecules of heavy heating oil; “reforming”- changing molecular structures of low quality gasoline, molecules; or “polymerization” – forming longer molecules from smaller ones. Conversion oil Refining.

Petroleum products are usually grouped into three categories; light distillate (LPG, gasoline, Naphtha), middle distillate (kerosene, diesel), heavy Distillate and residium (heavy fuel oil, lubricating oil, wax, asphalt).

This classification is based on the way crude oil is distilled and separated into fraction (called distillate and residuum).