Petroleum coke
Petroleum coke is a made of petroleum -derived solid, similar to the of coal produced coke mainly of carbon is. Another common name is oil pellets .
Manufacturing
The starting material for the production of petroleum coke are very heavy oils, which z. B. incurred as a residue in vacuum distillation . The bitumen is implemented in a coker . A common method is delayed coking . In addition to volatile hydrocarbons (gases and petrol), which are separated off, the coke is formed as a solid during cracking . The raw form is called green coke and can be further processed for refinement by calcining at high temperatures (1200 ° C). The remaining oil components are burned, the remaining calcine consists of almost pure carbon.
use
Green coke still contains hydrocarbons and is used as fuel in industrial heat generation, among other things. Calcined petroleum coke is used as electrode coke in the aluminum industry ( Söderberg electrode ) and in the heat treatment of steel . In steel production in the blast furnace process , high vanadium or nickel contents are even desirable. For the manufacture of electrodes for aluminum fused-salt electrolysis, the calcine should have the lowest possible metal content (contamination of the aluminum).
Risks
Its use as a fuel is problematic because of the heavy metals it contains (e.g. nickel , cadmium or vanadium ) or other elements such as sulfur and requires complex exhaust gas cleaning. Sulphurized petroleum coke thus indirectly promotes the emission of dioxins , which get into the environment together with the heavy metals emitted directly from the petroleum coke. Examples are the Scholven power plant in Gelsenkirchen in 2018 and the successor to the Oker lead smelter in the Oker - Harlingerode industrial area in the Goslar district of Lower Saxony in the period from 2017 to 2019. The district government of Münster classifies oil pellets as goods subject to mandatory disposal: In addition to hydrocarbons, the oil pellets also contain heavy metals such as nickel and vanadium. Therefore, they must be safely disposed of in approved facilities.
Web links
- Louis Hagel Mineralöl Handels-GmbH, Lexicon, entry petroleum coke
- Louis Hagel Mineralöl Handels-GmbH, Lexicon, entry Coker
- ExxonMobil, Mineralölverarbeitung , p. 10, Coker (production of petroleum coke) (PDF file; 2.79 MB)
Individual evidence
- ^ West German Broadcasting : Gelsenkirchen: Carcinogenic oil pellets in a coal power plant . As of September 27, 2018.
- ^ The daily newspaper : Zinkhütten in Lower Saxony: Poison in the blood? . August 6, 2019, accessed August 12, 2019.
- ^ Münster district government : [1] . January 24, 2020, accessed June 20, 2020.