Kerosene has been a vital liquid for centuries, used for lighting and powering machines. Today, it remains a significant fuel, especially in aviation and heating. Its production involves transforming crude oil into this useful substance.
Crude Oil: The Starting Point
Kerosene production starts with crude oil, a naturally occurring fossil fuel extracted from beneath the Earth’s surface. This complex mixture consists primarily of hydrocarbon molecules, formed over millions of years from ancient marine organisms. Crude oil serves as the raw material for producing many petroleum products, including kerosene. Its varied composition dictates the processes needed to separate its components.
Fractional Distillation: The Core Process
Fractional distillation is the primary method for separating crude oil into its components. This process heats crude oil to high temperatures, typically between 350°C and 400°C, causing most components to vaporize. The hot vapor then enters the bottom of a tall distillation column. This column contains multiple trays at different levels, creating a temperature gradient that is hottest at the bottom and progressively cooler towards the top.
As the crude oil vapors rise, they gradually cool. Different hydrocarbon fractions condense into liquid at specific temperatures corresponding to their boiling points, collecting on the trays at various heights. Lighter, lower-boiling point fractions, such as gasoline, rise higher before condensing. Heavier, higher-boiling point fractions, like fuel oils and asphalt, condense lower down or remain as liquid at the column’s base.
Kerosene, with a boiling point range between 150°C and 275°C, condenses in the middle sections of the column. This intermediate position reflects its molecular size and volatility. The collected kerosene still contains impurities and requires further processing.
Refining and Purification
Kerosene from distillation requires further processing to meet quality and safety standards. This refining stage removes undesirable compounds that can affect performance, cause corrosion, or produce harmful emissions. Desulfurization is a key purification step, often achieved through hydrotreating. In hydrotreating, kerosene reacts with hydrogen gas under high pressure and temperature with a catalyst, converting sulfur compounds into hydrogen sulfide gas.
Other impurities like nitrogen compounds, oxygenates, and aromatic hydrocarbons are also removed. These compounds can cause undesirable odors, reduce fuel stability, or increase soot formation during combustion. The refining steps ensure the final kerosene product has the necessary purity, color, and combustion characteristics for its applications.
Kerosene’s Properties and Uses
Refined kerosene is a clear, combustible liquid with a distinct odor and relatively low viscosity. It is less volatile than gasoline but more volatile than diesel fuel, making it suitable for applications requiring a controlled burn. Its most prominent use is as jet fuel, powering commercial aircraft. It also serves as heating oil in residential and industrial furnaces. Additionally, kerosene fuels lamps and stoves, and acts as a solvent in various industrial processes.