Petroleum. Distillation

Petroleum is an oily, thick flammable liquid, a mixture of various solid, liquid and gaseous hydrocarbons. Hydrocarbons are molecules that comprise of Hydrogen and Carbon. Petroleum is the general term for “unprocessed” crude oil. It is present beneath the Earth’s surface (Lithosphere) and forms when trapped, decomposed dead organisms buried in the sedimentary rock, and are heated under the immense pressure of new sedimentary layers over time (fossil fuel). The heat and pressure distilled the organic material into crude oil and natural gas.

Separation Processes

In order for Petroleum to be extracted for it’s functional consumer products, it must first be drilled. Once a site has been selected and the legal issues have been settled. A crew will go about to prepare the land. If the oil is located in shallow water, the rig will be built on ships or barges.

Oil Drilling Preparation1. The land must be cleared and levelled, roads may be built to optimise access. 2. Drilling is very water intensive, so there must be a source of water nearby. 3. A reserve pit must be dug, to dispose of the rock cuttings and mud.

After the oil has been recovered, It will be taken to an petroleum refinery to finalise the separation processes remaining. A petroleum refinery is an industrial process plant, they are typically large in size, employing hundreds of workers, with extensive piping running throughout and operate 24/7.

In chemistry, a separation process transforms a mixture of substances into two or more distinct products. The oil refining process begins with treating the fractions into mixtures by various methods such as reforming, cracking, alkylation, isomerisation and polymerisation. These new substances are then separated using fractional distillation or solvent extraction. Fractional distillation of petroleum is the process of separating the oil into different materials. Separation by distillation occurs when a liquid reaches it’s boiling point, the particles overcome the forces of attraction that hold molecules in their liquid state, they break away and transform into a gas state.

Hydrocarbons can be separated by distillation because they all have progressively higher boiling points and condensate at different temperatures. Longer chain molecules have higher boiling points because more energy is needed to separate contrary to short chain which have only weak forces of attraction. Each different chain length has a different property that makes it have beneficial functions. The final step in gasoline production is the blending of fuels with different vapour pressures, octane ratings and other properties to meet product specifications.

There is a diverse potential contained in crude oil because of the many invaluable uses it can hold. Petroleum products are often grouped into three categories: light distillates (Liquified petroleum gas, gasoline, Naphtha/Ligroin), middle distillates (kerosene, diesel) and residuum (heavy fuel oil, wax, asphalt, lubricating oils). Based on the way crude oil is distilled and separated into fractions they have been categorised in this fashion.

Liquified petroleum gas has endless capabilities and uses wherever light, heat or power is needed e.g. in the home, commercial business, industry, farms and transportation. It is commonly known as butane, ethane, methane, and propane.

Naphtha is a very flammable liquid used as a solvent for chemical industries. It can be found in washing detergents, shoe polishes. Gasoline is a volatile flammable liquid used to power vehicles, lawn mowers and is also used as a solvent. It’s ability to vaporise at low temperatures made it a useful fuel for many machines.

Kerosene is a combustible liquid, it is widely used to power jet engines of aircrafts, although it is commonly used as a cooking and lighting tool. At one point in time, kerosene was used in lamps and lanterns. Kerosene was a major fire risk.

Diesel fuel is an important liquid fuel because it offers a greater power density than other fuels, offering a more efficient performance. It is used in transportation e.g. buses, trains, boats, in construction and agriculture. Diesel fuel is also used to generate electricity by diesel engine-generators. Many buildings, facilities and hospitals utilise the diesel engine-generators for back-up and emergency supply. In Australia, diesel fuel is referred to as distillate.

Lubricating oil have the functions to reduce friction between moving surfaces, transfer heat, carry away debris, transmit power, prevent corrosion, sealant against gases, prevention of rust and is used as motor oil, grease and other lubricants.

Heavy fuel oil is a residue from crude oil, containing a lot of impurities. Due to it’s cheapness it is used in furnaces, boilers, large engines on ships and fired heaters. It is very viscous and requires to be kept at a high temperature in bunkers and storage tanks to ensure efficient transfer and combustion.

Asphalt is a sticky, black viscous liquid. The primary use of asphalt is constructing and maintaining roads, where asphalt concrete is created and used. The versatility of asphalt is extensive as it is a widely used material in recreation, agriculture, industrial and floorings. There is a large variety of asphalt mixes in order to provide the best suited performance for different sectors of it’s use.

Paraffin wax is a by-product of petroleum, it is a colourless, soft solid that is insoluble to water. It’s two primary properties are that it lacks reactivity and can burn at a slow, steady rate. The most common use of paraffin wax is in candle making. It is also used for coating to preserve foods, reduces the surface friction of surfboards, skis and snowboards. It is also the principle component in crayons because it is non-toxic.

Waste and Environmental concernsThere is no great deal of waste products from petroleum, many valuable products can be chemically converted into more saleable compounds. However, the atmosphere, hydrosphere and biosphere can be affected by the refinery operations.