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Refining. Industrial processes of separating, purifying, and altering raw materials. Coal, crude oil, oil sands, heavy oil and natural gas are non-renewable sources of fuels. They are also the primary sources of hydrocarbons.
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Refining Industrial processes of separating, purifying, and altering raw materials.
Coal, crude oil, oil sands, heavy oil and natural gas are non-renewable sources of fuels. • They are also the primary sources of hydrocarbons. • Refining is the technology that involves separating complex mixtures into purified components. • Some components of natural gas boil at temperatures as low as 20oC, and as high as 500oC. • The differences in temperature enable the separation of these compounds in a process called fractional distillation.
Fractional Distillation • The original is a mixture of liquids. • Each boils off at its boiling point and is cooled to form a fraction of the original mixture. • Crude oil, a mixture of many substances including a number of liquids, is refined in this way. • When crude oil is heated in the absence of air at 500oC, most of the constituent compounds vaporize. (The leftovers are asphalts and tars.) • Substances with higher boiling points condense at the bottom of the tower; substances with lower boiling points condense at the top of the tower.
Cracking More gasoline is needed than can be produced by fractionation. More gasoline hydrocarbons can be produced by cracking the available fractions.