Black carbon

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flaky soot deposits on a cleaning flap

Shiny soot or hard soot is the result of incomplete combustion, especially of solid fuels such as wood. This soot is deposited and can lead to a chimney fire. In painting, gloss black is used to make brown ink, a form of ink. A distinction must be made between the gloss black and the “flaky soot”, which is also created and deposited when using dry fuel, but which can be easily removed (for example by a chimney sweep ).

Emergence

The causes of incomplete combustion can be too high a moisture content in the fuel, for example wood with more than 20% residual moisture, furthermore a defect in the furnace, for example a fault in the return increase (if available), as well as insufficient combustion air supply or ash deposits in and in front of the stove pipe. A chimney cross-section that is too large for the fireplace can also lead to incomplete combustion. At low combustion temperatures, "soot" can condense in the chimney and later turn into shiny soot at higher exhaust gas temperatures.

consequences

In a wood heater (. E.g., pellet ) can be prepared by the deposition of shining soot in the coatings of the heat exchanger, the efficiency will be seriously affected the plant.

If the flue gases are cooled down too little before they are fed into the chimney (if too large a quantity of fuel burns after the furnace is overfilled and there is little excess air and / or if the return water is too hot), soot deposited in the flue can ignite ( chimney fire ). Temperatures of up to 1000 ° C can arise. A chimney fire must not be extinguished with water, as the sudden cooling with extinguishing water causes thermal stresses, which can cause the chimney to burst. Since one liter of water would suddenly be converted into 1700 liters of water vapor, the chimney can be severely damaged and, in the worst case, explode.

distance

In earlier times the leafy branches of the holly were tied to a rope and used to clean the chimney.

Since deposited hard soot cannot be removed by conventional chimney cleaning, this is done by setting the soot covering on fire under the supervision of the fire brigade or the chimney sweep. Special precautionary measures are taken to prevent furniture, wooden beams and other endangered material from catching on fire or the flames from the chimney from spreading to neighboring buildings. It is important to create a way to prevent the fire, for example by interrupting the air supply or powder extinguishing agent. Due to the high combustion temperatures, the gloss soot can swell to a multiple of its volume in the cold state and clog the chimney and thus the exhaust gas path.

If the exhaust gas path is blocked, the supervisory staff counteracts the blockage mechanically (a steel ball with or without a chimney broom is drained and pulled up again while the glossy soot is burning).

Another way to remove the glossy soot mechanically is with a chain removal device. This work is much faster than burning out the chimney. The chimney is also usually not damaged by this method. Hard and shiny soot in the chimney can be effectively removed with a flexible shaft. The flexible shaft is driven by a drill. The rotation spreads the chains of the chain head and knocks off the soot. With the flexible shaft, clockwise / counterclockwise rotation is possible, which gives a particularly high cleaning effect.

Individual evidence

  1. ^ Gloss black. kaminholz-experte.de, accessed on March 18, 2020 .
  2. ^ Franz-Josef Sehr : The fire extinguishing system in Obertiefenbach from earlier times . In: Yearbook for the Limburg-Weilburg district 1994 . The district committee of the district of Limburg-Weilburg, Limburg 1993, p. 151-153 .
  3. ^ Roy Bergdoll, Sebastian Breitenbach: Die Roten Hefte, Heft 1 - Burning and Extinguishing . 18th edition. Kohlhammer, Stuttgart 2019, ISBN 978-3-17-026968-2 .
  4. ↑ John Seymour: The Great Book of Life in the Country. A practical guide for realists and dreamers. Urania, Berlin 1999, ISBN 3-332-01060-3 .

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