Brine
As salt coal is coal , usually brown coal , referred to an increased content of over 4% of alkali metal salts , especially sodium chloride and sodium sulfate comprising.
Origin and occurrence
Lignite is often found in close proximity to rock salt deposits . This results from the way in which the two sediments were formed . The coal was created from dying biomass as a result of the flooding of forests and moors. If the water is salty sea or brackish water or strongly mineral water from saline rock and this water evaporates again shortly after the flooding, the salts contained in the water are concentrated and are partially deposited between or in the biomass layers from which The coal seams later formed through coalification .
The best-known salt coal deposits in the German-speaking region are in the Helmstedt and Central German lignite districts near Helmstedt , Halle / Merseburg , here in particular in the Ammendorfer district , and Egeln . Significant salt coal deposits outside Germany are in Australia and the Donets Basin .
Combustion behavior
When combustion is salt coal is problematic. This results from two effects of the chemical elements contained in the salts:
- The contained alkali metals, such as sodium and potassium, act as fluxes and significantly lower the softening point of the coal ash , so that the furnace and the mostly downstream steam boiler tend to form slag . Only special combustion chambers such as fluidized bed combustion or melting chamber combustion are therefore suitable for combustion .
- The contained non-metals sulfur and chlorine are converted into sulfur dioxide and hydrogen chloride during combustion . In combination with water in the form of sulphurous and hydrochloric acid, these are on the one hand corrosive and attack the materials of the combustion system, on the other hand they are air pollutants that have to be removed from the flue gas by a complex cleaning process to comply with the emission limit values and to avoid acid precipitation .
The largest coal-fired German coal-fired power plant is the Buschhaus power plant in the Helmstedt district.
literature
- Helmut Effenberger: Steam generation . Springer, 1999, ISBN 3-540-64175-0 ( limited preview in Google book search).
- Helmut Stapf: Mining Chemistry . Fachbuchverlag Leipzig, Leipzig 1954, p. 318 .
- H. Lehmann: Origin and distribution of the salt coal . In: Mining and Energy Industry . tape 2 , no. 2 , 1949, p. 55-58 .
Individual evidence
- ↑ a b c Effenberger (see literature), pp. 24–27.
- ↑ Lexicon of polluting air pollution and climate change: Salt coal. Federal Research and Training Center for Forests, Natural Hazards and Landscape , accessed on October 31, 2012 .
- ^ Leonhard Müller: Handbook of the electricity industry: Technical, economic and legal foundations . 2nd Edition. Springer, 2001, ISBN 3-540-67637-6 , pp. 203 ( limited preview in Google Book search).
- ↑ a b Bernd Hartmann: The genesis of the material inventory of the lignite seam Bruckdorf (Obereocene) between Halle and Bitterfeld, Saxony-Anhalt . Dissertation. Martin Luther University Halle-Wittenberg, 2005 ( full text as PDF ).
- ↑ Werner Boie : The use of salt coal . In: Energy technology . Vol. 6 (1956), No. 2 , p. 64-66 .
- ↑ a b Effenberger (see literature), p. 319f.