Petroleumcoke

Petroleum coke is a black solid, obtained mainly by cracking and carbonizing residue feed stocks and from the distillation of heavier petroleum oils. The main commercial applications of petroleum cokes depend on their properties and they are typically used as energy sources for solid fuel applications such as lime and cement kilns and sometimes as fuel for boilers and power generation. Some calcined cokes are used in the manufacture of electrodes for aluminium and steel electro smelting.

Composition of Petroleum coke

The compositions of all petroleum cokes are highly feedstock dependent and also vary from
location to location depending on the types of processes used. Generally speaking, petroleum
cokes contain some proportion of all the elements which exist in the crude oil/feedstock used
in the process. Therefore, each form of petroleum coke has its own distinctive qualities. 
The compositions of calcined cokes are directly related to the green cokes from which they are
produced, except for the effects of the lower volatiles content noted above.

Because of the dependence of a petroleum coke's properties on the crude oil source of the
feedstock and the specific process used, the analyses can have a wider or smaller spread
than those indicated.

 

The compositions of the petroleum cokes typically lie in the following ranges:

  • Carbon 84 - 97%
    Sulphur 0.2 - 6%
    Volatile matter 2 - 15%
    Hydrogen Up to 5%
    Iron 50 - 2000 mg/kg
    Vanadium 5 - 5000 mg/kg
    Boron 0.1 - 0.5 mg/kg
    Nickel 10 - 3000 mg/kg

Manufacturing of Petcoke

Green coke (delayed coke) has a distinctive hydrocarbon smell. It can contain up to 15% volatile material, mostly hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs).

Calcined coke purity is largely feedstock dependent. Needle coke and regular coke are calcined cokes of different purities, 1 the needle coke being the purer form which is used for electrodes production.

Calcined coke, as a consequence of the calcining process, has a virtually zero volatile content. It is inherently a much dustier material than green coke and depending on its use it is usual to add a small amount (0.3% wt or less) of high viscosity oil or a very small amount of surfactant usually in a water solution to act as a dust suppressant.

Fluid coke has spherical grains and contains less volatile material than green coke.

The normal grain size of fluid coke is less than 6 mm.

Flexicoke is similar to fluid coke but contains even less volatile material and has much finer grains and thus is more dusty.