What is Petroleum coke?
Petroleum coke is a carbonaceous product obtained in the oil refining process. It is abbreviated as Coke or Petcoke, and is a carbon-rich solid material derived from final cracking process — a thermo-based chemical engineering process that splits long chain hydrocarbons of petroleum into shorter chains— that takes place in coker units. There are two distinctive grades of Petroleum Coke viz. calcined petroleum coke or Green Petcoke and Fuel Grade Petcoke.
Petcoke is a direct replacement of coal as a fuel but has higher calorific value (>7800Kcal/Kg as compared to 3500-4500 Kcal/Kg for coal). Global production of petroleum coke or petcoke, as it’s commonly known, has been steadily increasing since the late 80s. But innovations in bitumen extraction have allowed petcoke production to shoot up in recent years, and U.S. exports of petcoke have risen by the barrel load: 184 million barrels in 2012, to be precise. petroleum coke uses
Benefits of Fuel grade Pet coke over coal:
- Petcoke is a direct replacement of coal as a fuel but has higher calorific value (>7800Kcal/Kg as compared to 3500-4500 Kcal/Kg for coal).
- Petcoke is hydrophobic as compared to coal which is hydrophilic, thereby having edge during rainy season.
- Being solid fuel, Petcoke has low volatile matter thus no evaporation losses. Helps saving in transportation cost due to higher density compared to liquid fuels.
- Low ash content.
Industrial Uses of calcined petroleum coke
Petcoke can take two different forms: green petcoke which is used as a fuel and calcined petcoke which is used as a feedstock by manufacturer for a wide range of products such as aluminum, paints, coatings and colorings which are used by millions of people.
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1. Fuel |
About 80 percent of worldwide petcoke production is “fuel-grade” petcoke (green coke), used for electricity generation and in cement kilns. |
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2. Brick and Glass |
Calcined petcoke is used by brick and glass manufacturers because it has a significantly lower ash content compared to other fuels. |
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3. Aluminum |
Calcined petcoke is necessary to make anodes for smelting and is the only commercially viable method to do so. It boasts a superior combination of electrical conductivity and resistance to chemical and physical degradation in the smelting pot, which contains lower levels of contaminants (i.e. ash). |
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4. Fertilizer |
Calcined petcoke is gasified to produce ammonia and urea ammonium nitrate, which is then used in fertilizer production. |
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5. Steel |
Calcined petcoke is a partial replacement for metallurgical coal as a feedstock for coke oven batteries, and as a partial substitute for pulverized coal directly injected into blast furnaces. Petcoke that is specially produced to have a needle-like crystal structure is called needle coke. Needle coke is used to produce the electrodes used in electric arc furnace (EAF) steel production. No other material has needle coke’s combination of electrical conductivity and physical properties required for EAF electrodes. |
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6. Paper |
Calcined petcoke is gasified to produce ammonia and urea ammonium nitrate, which is then to produce pulp and paper. The TiO2 that is produced from calcined petcoke is also used as a mineral that is then used as a whitener for paper. |
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7. Brick and Glass |
Calcined petcoke is used by brick and glass manufacturers because it has a significantly lower ash content compared to other fuels. |
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8. Paint and Colorings: |
Calcined petcoke is used in the production of titanium dioxide (TiO2 ), a mineral that is used as a substitute for lead in paint. TiO2 is also used as a pigment in sunscreen, plastic and food coloring. |
Environmental implications of PetCoke mining
Petroleum coke (’petcoke’) is a bulk by-product of oil refining. Most petcoke (approximately 75%) is sold as a fuel for power generation and cement production, but the higher quality petcoke is sold for the calcining industry. It is commonly transported at sea in bulk carriers. As with most other bulk cargoes, after discharge there remain residues in the holds and on deck which must be cleaned before new cargoes can be loaded. The major implication of petcoke contamination from Petroleum coke bulk cargo are mainly
- Tank washing
- Cleaning products
- and discharge implications
Petcoke is an extremely stable fuel which means there is little risk of combustion during transportation, but due to its high carbon content when it does combust it releases up to 10% more CO2 per unit of energy that normal coal. That’s higher than almost any other energy source in existence and makes pet coke prices a huge contributor to the creation of greenhouse gases.
Petroleum coke uses and hazards
It’s not just carbon that makes petcoke an environmental concern. Increased pollution controls are required during petcoke combustion to capture the excess sulphur found in low grade petcoke. The heavy metal content of petcoke has also left many worried, both at the effects of releasing it into the air when petcoke is burned, and the implications it has for the local environment during storage. This is a particular concern for environmental campaigners in Chicago, where large amounts of dusty petcoke from nearby refineries are stored uncovered, although studies by North American petcoke producers indicate that the risk to the human respiratory systems is no different to regular coal.
Despite the environmental concerns connected to the manufacture and use of petcoke, it remains popular due its cost effectiveness. It’s inexpensive to manufacture yet easily exported, and provides an attractive source of cheap fuel for developing nations. As long as this win-win relationship between importer and exporter continues, it’s unlikely that we’ll see production slow any time soon.
Storage and Transportation
Petcoke is safely stored and handled by refineries, intermediaries and end-users. It is transported by ocean freight, barges, rail and truck.
- A majority of refineries that produce petcoke store and manage it in an uncovered venue.
- 87 percent of intermediaries store petcoke uncovered venue.
- 78 percent of customers and end-users store petcoke uncovered venue.
- All employ a variety of dust/control management practices to limit fugitive dust.
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