Green Petroleum Coke (GPC)
Petroleum coke (petcoke) is a blackcolored solid composed primarily of carbon, and may contain limited amounts of elemental forms of sulfur, metals and non-volatile inorganic compounds. Petcoke is the co-product of several processes used in petroleum refining to upgrade “residuum” into gasoline and middle distillate-range fuels. Although it is a refining co-product, petcoke has economic value as both a heating fuel and raw material in manufacturing.
Petcoke may be combusted as fuel in industrial and power generating plants. Cement plants and power plants are currently the two greatest consumers of petcoke. There is some limited use as space heating and in commercial brick kilns in Europe, and a small but emerging market as a metallurgical coal blending component for the steel industry.
Fuel grade petcoke can substitute for “steam coal” in power plant boilers, having the advantage of a higher heating value (discussed below). Conventional coal-fired boilers can blend petcoke with steam coal, and newer boiler designs have replaced steam coal with petcoke entirely. Cement plants consume fuel-grade petcoke in rotary kilns.
Petcoke is composed primarily of carbon. The specific chemical composition of petcoke depends on the composition of the petroleum feedstock used in refining.
Coking initially converts petroleum residuum into lighter range hydrocarbons; low-Btu gas that can serve as a fuel in refinery operations; and “green coke.” Green has the meaning of unprocessed.