Middle distillates are used primarily as fuel for heating, lighting and transportation globally. When crude oil is refined, middle distillates make up between 25% and 40% of the oil products yield. Physically they are clear, colourless to light yellow, flammable liquids with shorter carbon chains than lighter distillates but longer than residual products.
Jet Fuel - or Aviation turbine Fuel (ATF) – is a refined, unleaded kerosene-based (at times naphtha-kerosene blend) colourless to straw-coloured aviation fuel used in turbine engines (jet engines & turboprops).
Types of Jet Fuel:
Jet Fuels are mainly characterized into two types:
Jet A-1 is a kerosene grade of fuel suitable for most turbine engine aircraft. It has a flash point minimum of 38°C and a freeze point maximum of -47°C. Jet A1 is the standard specification fuel commonly used across most of the world. It meets stringent international requirements, particularly those of the latest versions of the AFQRJOS (Aviation Fuel Quality Requirements for Jointly Operated Systems), the British DEF STAN 91-91 standard, the ASTM D1655 standard, and the NATO F-35 specification.
Jet A is a kerosene-based fuel, mainly used domestically in the U.S.A. It has the same flash point as Jet A-1 but a higher freeze point maximum (-40°C). It is supplied against the ASTM D1655 (Jet A) specification. Jet A1 has a lower freezing point (-47°C) than Jet A (-40°C), making it suitable for long-haul international flights, particularly those overflying polar routes. Similarly, unlike Jet A, Jet A1 has static dissipater additives, which decreases any static charges that can form during the movement of the fuel.
Jet B is a naphtha-kerosene fuel containing a light mixture of 70% gasoline and 30% kerosene. Jet B has a low freezing point of -60˚C, making it suitable for countries with extremely low temperatures such as Alaska and Canada (CAN/CGSB 3.23).
TS-1 is the main jet fuel grade available in Russian and CIS states made to Russian standard GOST-10227. Compared to Jet A1, it has slightly higher volatility (flash point of 28˚C minimum) and a lower freeze point (<-50˚C) for enhanced cold weather performance.
BBP currently supplies solely commercial-grade, kerosene-based Jet A1.
Aviation Gasoline (AVGAS/aviation spirit) is used to power traditional propeller aircraft and small piston-engine airplanes. This includes aircraft operated by private pilots, flight training jets, and flying clubs.
There are two main types of, which are AVGAS 100 and AVGAS 100LL. The 100 in both types refers to the octane rating. AVGAS contains small amounts of tetraethyl lead, a substance that prevents harm to the engine detonation or knocks. AVGAS 100LL (low-lead) has a lower amount of tetraethyl lead additive (TEL).
However, it is a toxic substance for humans in case of inhalation or absorption into the bloodstream. For this reason, the Federal Aviation Authority (FAA) is cooperating with the US Environmental Protection Agency (EPA) to eliminate this substance from AVGAS.
At the time of writing, BBP does not deliver AVGAS due to its TEL content. The intent is to supply an Avgas grade currently under research in parts of the world, which will be a complete unleaded replacement for the current leaded grades. At the time of writing, this fuel is not commercially available.
LIGHT CYCLE OIL
Light Cycle Oil (LCO) is the diesel boiling range material, which is produced in addition to gas and petrol in the Fluid Catalytic Cracking Unit (FCCU).
LCO is treated in the diesel hydro-treater (DHT) unit to produce low sulphur environment friendly diesel. However, LCO is a poor diesel fuel-blending component without further processing. Upgrading LCO can be achieved in a number of ways, including: hydro-treating, high pressure hydro-cracking for full conversion of LCO into naphtha and a more optimized partial conversion hydro-cracking process.
The optimised partial conversion hydro-cracking process provides an effective and flexible process to process LCO into desired products such as very-low sulphur diesel and high-octane high-aromatics naphtha.
Diesel fuel is one of the valued middle distillate products that is used as fuel for motor vehicles (cars, trucks, buses) that use the compression ignition engine.
The diesel fuel produced by a refinery is a blend of all the appropriate available streams: straight-run product, FCC light cycle oil, and hydro-cracked gas oil. The straight-run diesel may be acceptable as is, or may need minor upgrading for use in diesel fuel prepared for off-road use.
To meet the 10 ppm (ULSD sulphur limit), all the streams used to prepare diesel fuel need hydro-treating to raise its Cetane number and lower the sulphur concentration and stabilize it before blending into diesel fuel.
The principal measure of diesel fuel quality is its cetane number. A cetane number is a measure of the delay of ignition of a diesel fuel. A higher cetane number indicates that the fuel ignites more readily. European (EN 590 standard) road diesel has a minimum cetane number of 51.
Octane additives increase the compression combustion resistance of gasoline. Cetane additives reduce the compression combustion resistance of a fuel. Both cetane and octane are measures of how much pressure a fuel can withstand before auto-ignition. Straight-run gasoline — gasoline without octane additives — is often weak to pressure and requires greater resistance.
Straight-run diesel, on the other hand, is often too resistant. That means a diesel engine with straight-run diesel will not start in cold weather, low-temperature conditions. Increasing the octane rating and weakening diesel’s pressure resistance allows engines to fire in the cold more easily.
Diesel is categorized by its uses:
Automotive Gas Oil (AGO) - also known as Automotive Diesel Oil (ADO) - is a straw-coloured fuel intended for on-road heavy-duty vehicles (trucks, buses) and light-duty vehicles (vans & cars) powered by diesel compression ignition engines.
Industrial Gas Oils (IGO) are used for off-road diesel engines such as agricultural tractors, road construction machinery. It is dyed red for easier identification (red diesel).
Typically, a standard defines certain properties of the fuel, such as cetane number, density, flash point, sulphur content, or biodiesel content.
Cetane - Measure of the tendency of diesel fuel to auto-ignite when injected into the combustion chamber of a diesel engine
Sulphur content - Measure of the sulphur remaining in the fuel. Lower sulphur is more desirable. Sulfur content is measured as ppm/wt%
Cloud point - Indicator of the tendency of a fuel to form wax crystals when cold. Lower cloud point is more desirable
Pour point - Measure of the tendency of a fuel to become more viscous and resist flowing when cold. Lower pour point is more desirable
Flash point - Temperature at which a fuel emits enough vapour to form a combustible mixture of hydrocarbon and air. Higher flash point is more desirable
Diesel fuel standards include:
EN 590 (European Union)
ASTM D975 (United States)
GOST R 52368 (Russia; equivalent to EN 590)
NATO F 54 (NATO; equivalent to EN 590)