الوصف

Diesel fuels are complex compounds of hydrocarbon molecules, which generally boil within the temperature range of **0 °C to **0 °C. They are normally blended from several refinery streams, mostly coming from the primary distillation unit. However, in a conversion refinery, components from other units, like cracking processes, are often used to increase diesel fuel production. In the primary refining unit, distillation takes place at atmospheric pressure, the furnace temperature being set to give maximum distillation without cracking. The quality and quantity of the streams drawn off will be determined both by their boiling range and by the crude boiling used.

Diesel fuels are complex hydrocarbon mixtures, containing all the classes of hydrocarbons: paraffins, naphthenes, aromatics, and in small concentrations, olefins. They are manufactured to meet the property limits of the specifications and regulations, and not to achieve a specific hydrocarbon distribution by class and size. But, to varying degrees, the property limits define the chemical composition of the fuel. The volatility of a diesel fuel is expressed by its distillation curve. Each individual hydrocarbon boils at a specific temperature called its boiling point and, in general, the boiling point increases with molecular size. Consequently, defining a distillation curve is equivalent to defining a certain distribution of hydrocarbons with a range of sizes. The temperature limits of the distillation curve exclude smaller hydrocarbons with lower boiling points and larger hydrocarbons with higher boiling points.