Wood briquette
Wood briquettes are a form of wood fuel that is made by mechanically pressing dry, untreated wood particles, such as wood shavings or sawdust . The resulting briquettes have a diameter of at least 25 millimeters; smaller pellets are known as wood pellets . The briquettes have a uniformly high density and a uniform cross-section, often also a uniform length.
General
Wood briquettes produce less ash (100 kg of wood briquettes produce less than 1 kg of ash) and have a lower sulfur content than lignite. The CO 2 balance is neutral - if you do not take into account the energy requirements for transporting and manufacturing the wood briquettes, because the wood briquettes only release as much CO 2 into the atmosphere when they are burned as a growing tree absorbs through photosynthesis .
For wood briquettes, ISO 17225 "Biogenic solid fuels - fuel specifications and classes" will apply worldwide from September 2014. Part 3: Classification of wood briquettes and Part 1: General requirements are used. Until then, EN 14961 “Solid biofuels - fuel specifications and classes” applied. Part 1 “General requirements” and Part 3 “Wood briquettes for non-industrial use” were used. Until September 2011, requirements and tests for untreated wood briquettes and pellets in Germany were standardized in DIN 51731.
Wood briquettes can be certified according to DIN EN ISO 17225-3. The DINplus quality mark, awarded by DIN CERTCO mbH, shows consumers that the wood briquettes meet all the requirements of DIN EN ISO 17225-3. In addition to the requirements of the standard, the abrasion behavior is tested. The tests of the chemical analysis and the abrasion behavior must be proven annually in order to be able to extend the DINplus certificate.
According to ISO 17225-3, the following requirements apply to wood briquettes:
Water content ≤ 12% (in delivery condition)
Ash content (550 ° C) ≤ 1.0% (anhydrous)
Density ≥ 1.0 g / cm³ (in delivery condition)
Additives ≤ 2% ( anhydrous) The type and quantity must be specified. Calorific
value ≥ 15.5 MJ / kg, ≥ 4.3 kWh / kg
Calorific value and burning time
The low water content of less than 10% is one reason for the high energy content of 4.8 kWh to 5.5 kWh per kg.
For comparison:
- Forest fresh wood with a water content of 50% has approx. 2.5 kWh / kg,
- 1000 kg of wood briquettes correspond to the energy content of approx. 2.25 cubic meters of dry firewood (humidity 20%).
When it comes to briquettes, hardwood also has advantages over softwood. The briquettes are pressed to the same specific weight (1 to 1.2 t / m³). The greatest disadvantage of resinous softwoods is that they burn too quickly and that the resin is unstable in shape. The briquette disintegrates faster and the escaping resin vapor cannot be completely burned in normal wood-burning stoves, which is also shown by the black panes of the stove. Good hardwood briquettes burn much cleaner and also produce less fine dust.
The smoother and firmer a surface, the longer it takes the flames to "eat through". Hardwood briquettes are often produced from fine grinding chips (for example parquet production); they therefore have a more homogeneous and firmer surface. Softwood briquettes, on the other hand, are often pressed from wood shavings. Their surface is coarser and therefore quicker to ignite. They are therefore suitable for lighting a fire and for generating heat quickly, while hardwood briquettes are more suitable for holding embers and for generating heat a little longer. The flame duration of hardwood briquettes can last from half an hour (for example bark briquettes) to two hours (for example softwood briquettes).
Round Pini & Kay wood briquette
Pini & Kay wood briquette
Bark briquette
See also
- Wood heating
- Wood pellet
- Splitting pliers
- Energy wood - wood which is to be used exclusively for generating energy through combustion
Individual evidence
- ↑ Which is the best wood briquette? Wood types & shapes in comparison! In: Wood Harry. May 7, 2019, accessed March 10, 2020 .