Petcoke yield is mainly dependent on the carbon content of the feedstock, while the structural quality of the Petcoke is influenced chiefly by the type of feed, i.e., virgin crude or cracked products. The chemical and physical characteristics of Petcoke are a function of the crude oil and refining technology used by the refinery. Chemically, Petcoke contains a variety of elements mainly Carbon, Hydrogen, Nitrogen, Oxygen and metals in a wide range of concentrations depending on the feedstock. Physical appearance of Petcoke resembles to spheres of different sizes known as Shots, hence called as Shot Coke. It may resemble a sponge with pores called as “Sponge Coke”. The physical appearance is a property of the crude, the temperature at which coker is operated and the coker process cycle time.The hardness of coke is defined in HGI (Hard Grove index), which indicates difficulty of grinding ability of the product.
Depending on these physical and chemical characteristics, Petcoke is typically used in either an energy application, as a source of Calories or in an industrial application, as a source of carbon.
Fuel grade Petcoke generally replaces furnace oil, lignite and coal. It has high calorific value of 8200 kcal/kg(DB) and produces practically negligible ash when burned. It is commonly used in applications like boilers, cement kilns, glass furnaces, lime kilns, reducing agents, carbon enhancers etc.
Generally, Fuel grade Petcoke is produced from vacuum residues that have high sulfur contents. High sulphur Petcoke is used as fuel whereas low sulphur Petcoke is used in producing anodes.