Petroleum coke (often abbreviated petcoke) is a carbonaceous solid derived from oil refinery coker units or other cracking processes. Other coke has traditionally been derived from coal. Petroleum coke is a heavy fuel source produced when oil refiners split crude oil into different commercial products. Like coal, pet coke can be burned to generate power, and can be gasified in order to provide cleaner-burning "substitute natural gas," along with other commercial byproducts.
Marketable coke is coke that is relatively pure carbon and can be sold for use as fuel (i.e. fuel grade coke), or for the manufacture of dry cells, electrodes (ie anode grade coke). Needle coke, also called acicular coke, is a highly crystalline petroleum coke used in the production of electrodes for the steel and aluminum industries. Catalyst coke is coke that has deposited on the catalysts used in oil refining, such as those in a fluid catalytic cracker. This coke is impure and is only used for fuel.
Its high heat and low ash content make it a good fuel for power generation in coal fired boilers, but petroleum coke is high in sulfur and low in volatile content which pose some environmental and technical problems with its combustion. In order to meet current North American emissions standards some form of sulfur capture is required. Fluidized bed combustion is commonly used to burn petroleum coke. Gasification is increasingly used with this feedstock (often using gasifiers placed in the refineries themselves).
Calcined petroleum coke (CPC) is the product from calcining petroleum coke. This coke is the product of the coker unit in a crude oil refinery. The calcined petroleum coke is used to make anodes for the aluminium, steel and titanium smelting industry. The green coke must have sufficiently low metals content in order to be used as anode material. Green coke with this low metals content is referred to as anode grade coke. The green coke with too high metals content will not be calcined and is used for burning. This green coke is called fuel grade coke.
At the Brayton Point power station in Massachusetts, petroleum coke is being tested as fuel in combination with coal and biomass (such as wood chips, corn stover, switch grass, and wood waste) in a new coal gasification pilot facility. The gasification facility is operated by GreatPoint Energy of Cambridge, MA.
Leucadia's Mississippi Gasification SNG project has Department of Energy loan coverage of $1.689 billion to produce syngas from petroleum coke feedstock, for sale to electric utilities in the region, with proposed carbon capture for enhanced oil recovery.
- International Union of Pure and Applied Chemistry, "Petroleum coke", "Compendium of Chemical Terminology" Internet edition.
- Toby Shute,[http://www.fool.com/investing/value/2008/05/12/leucadias-unnatural-gas.aspx "Leucadia's Unnatural Gas" The Motley Fool, May 12, 2008.
- "Phasing Out Federal Subsidies for Coal" Synapse Energy Economics Report, April 2010.
- IUPAC definition of various forms of solid carbon.
- Table of contents of an annual calcined petroleum coke report
- BP info on how calcined petroleum coke is produced