Jet fuel production

From crude oil to fuel for flight: how jet fuel is produced

Paola Leibbrandt
12.10.2018
1 picture
4 minutes

Aviation fuel, aka Jet A-1, is used to power most civilian aircraft. But what goes into producing it? This article explains how jet fuel is produced from crude oil.

Where it All Starts: Crude Oil

Fuels like petrol, diesel and aviation fuel are produced from crude, or fossil, oil. This is untreated mineral oil which consists mainly of hydrocarbons and which is produced by the decomposition of organic materials, such as plankton and algae. The oil is extracted by drilling to allow further processing, which involves using a variety of separation and preservation processes to transform the crude oil into the raw materials for generating warmth and electricity. Crude oil is also used to create synthetic materials. Due to its many usage applications, crude oil is also known as “black gold”.

How Crude Oil is Extracted

Crude oil is extracted in three phases. First, the oil must be raised to the earth’s surface, either through the pressure of natural gas or by pumping. In the second phase, water or gas is injected into the oil reservoir. In the third phase, complex substances, such as steam, polymers and the like, are used to bring up more oil. If the oil deposits are beneath a lakebed or the ocean floor, drilling platforms are set up from where the oil can be brought to the surface. If the deposits are close to the earth’s surface, the oil can also be mined directly. The oil is then transported (via either sea or land) to the processing plant.

Conventional Jet Fuel Production – The Refining Process

Complex chemical processes are required to produce jet fuel from crude oil. This is where the different boiling points of hydrocarbons come in handy. In total, crude oil contains over 500 components.

In the refinery, crude oil is placed into what is known as a fractionating column, a kind of distillation tower, where it is separated into its major components. To do this, it is heated to 400 degrees Celsius. At this temperature, it vaporises and enters the fractionating column in gaseous form. The temperature inside the column decreases towards the top. As each of the crude oil’s components reaches its boiling point, it liquidises and flows into one of the bubble-cap trays.

At just under 400 degrees Celsius, lubricating oils, waxes, paraffins and bitumen condense. Lighter components liquidise higher up, with heating oil and diesel separating at around 360 degrees. The middle distillate, with a boiling point of 250 degrees Celsius, becomes kerosene and petroleum. At 80 degrees Celsius, we get light gasoline, while methane, propane, butane and ethane condense right at the top of the column. The liquid components are drained off at the side of the fractionating column.

This video from BP provides virtual insights into a crude oil refinery (German).

Aviation Fuel

Additives for All Seasons

In the next step, the intermediate products from the refining process are desulphurised and refined. In order to create usable jet fuel, additives are added. These include, for example, anti-static substances to prevent static charging and anti-corrosive agents to inhibit corrosion in the tanks. To prevent the formation of ice crystals at high altitudes and low temperatures, de-icing agents are added. A wide range of other additives are also used for certain environments, including biocides for environments in which bacteria could occur. Jet fuel is slow to ignite, remains liquid at low temperatures, and burns almost without residue: all that remains are water and carbon dioxide.

Civilian and Military Uses of Aviation Fuel

In today’s civil aviation, Jet A (used only in the US) and Jet A-1 are used. The difference between the two lies in their freezing points: Jet A freezes at –40 degrees Celsius, while Jet A-1 does not freeze until the temperature reaches –47 degrees Celsius. Various fuels with specific properties have been developed for military use. There are, for example, types of fuel with extremely low freezing points or high flash points, as well as fuels with extremely low flammability levels.

Producing Alternative Fuels

Nowadays, aviation fuel can also be manufactured in synthetic and CO2-neutral forms. These are, however, around twice to three times as expensive to produce as the conventional form. Alternative aviation fuels can also be blended with and used in place of conventional aviation fuels. These “drop-in” fuels are subject to the same high safety and quality requirements. This means that they are immediately ready for use and require no modification to either the aircraft or the refuelling process. Alternative jet fuels can, for example, be made from organic materials or from renewable energy sources.

Bilder Pixabay – reverent, catmoz

by Paola Leibbrandt

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