A charcoal pile or charcoal clamp is a carefully arranged pile of wood, covered by turf or other layer, inside which a fire is lit in order to produce charcoal. The pile is tended by a charcoal burner. It is similar to a charcoal kiln, but the latter is usually a permanent structure made of materials such as stone.
Since antiquity, charcoal piles have been used to make charcoal. Charcoal is much lighter than natural timber and therefore easier to transport. In addition, charcoal generates much more heat. Charcoal production was therefore an important part of the economy in early modern times. At that time, charcoal was the only fuel that could generate the heat necessary for iron smelting. In the late 18th century, it is recorded that the duties of a master coalman at an ironworks were not only to ensure the supply of charcoal and to supervise charcoal burners and their assistants, but also to visit frequently the charcoal clearings (Kohlhäue) i.e. those parts of the forest used to produce charcoal. [1]
In 1713, a process was invented for producing coke suitable for blast furnaces from hard coal (stone coal). From then on, the consumption of the more expensive charcoal decreased steadily despite increasing iron production. From the 17th century onwards, pitch furnaces were increasingly used and in the 19th century retorts were also employed. As a result, fewer and fewer charcoal piles were used. The gradual decline of charcoal began in the 19th century, when hard coal practically replaced charcoal and later also town gas and electricity became more important. The Second World War triggered a strong demand for charcoal again. At that time, motor vehicles were also powered by wood or charcoal.
Today it is of no particular economic importance, in particular due to the loss of wood gases during charcoal production, the calorific value yield from wood is extremely low. Charcoal burning is still used only for traditional reasons and for some special applications of charcoal.
In order to produce charcoal, water and the volatile components of the wood have to evaporate. At the charcoal burning site, which is located where possible near a body of water so that it can be extinguished later, the wood pile is built in approximately hemispherical or conical piles, using short logs, mostly one-metre long, in even fashion (standing or lying down), around the central chimney (Quandel). A bank of ash and earth (Stübbewall) can be built all round the pile.
On top of this an airtight roof is constructed of dry fir branches, leaves, hay or straw, or alternatively of grass, vegetation and moss. Finally the pile is sealed airtight with a mix of ash and charcoal pieces (possibly known as 'culm' or 'brusque'; German: Lösche, Stübbe, Stibbe or Gestübe) and earth, with the exception of the central chimney. A support made of logs and planks is then built round the base of the pile. Then the pile is ignited via the chimney which is then also sealed.
A sure sign that the charring has started is the so-called 'knocking' of the pile; the intense heat causes deflagration of wood gas which, if the covering of the pile is too strong, can lead to an explosion. At the top as well as at the foot of the pile, individual holes are made in the surface, by means of which the fire in the pile is regulated. Under this blanket, incineration is conducted with carefully regulated air access in such a way that, if possible, no more wood burns than is absolutely necessary to heat the entire wood mass to the charring temperature. The wood must char, not burn, inside the pile; air being let in through the small holes so that no fire can start. But it creates a lot of heat and the water evaporates, tar condenses on the green roof, the smoke is yellowish-white and odourless. [2] The heat of the smouldering wood inside the pile drives all liquid and organic components out of the wood as smoke.
The job of the charcoal burner at this stage is to neither let the pile go out nor to let it burn down as a result of too much air over the following days or weeks (depending on the size of the pile and the weather). To do this, he drills and closes the air holes. Essentially, only the gases and vapours that develop from the heated wood should burn. By observing the smoke and its colour, the charcoal burner knows whether there is too much or too little air. The colour of the smoke that escapes indicates whether charring is complete. If the smoke is white and dense, the wood is not yet charred. If it is light, almost transparent and slightly bluish, the wood is charred. The air holes are now moved further down in order to also draw the fire into the lower areas of the kiln. Each time the draft holes are moved, the smoke colour changes, the kiln charred from top to bottom. As the charring progresses, the kiln slowly sinks in.
Once charring is complete, the fire in the pile is quickly extinguished by the clogging of the air holes. [2] and the pile slowly begins to cool down. For better sealing the pile is often sprinkled with water and compacted with a wooden hammer. The pile has now shrunk to about half its original volume. Now the cover is opened and then the coal is pulled out with a rake, fork or shovel and spread out to cool down. Embers are extinguished with water or smothered with ash. If this is not done properly, the charcoal that has been produced burns within a very short time under great heat (exothermic reaction). The heat generated in this process is so great that it is impossible to approach the pile. The coal must now cool down for at least 12 hours. If the charcoal is too small it remains in the pile and is mixed with the ash. Only the carbon skeleton of the wood cells remains but this is still 98% of the wood. From 100 kg of hardwood, approximately 30 kg of charcoal can be obtained.
During charcoal production, by-products are generated such as wood tar, wood vinegar, wood spirit and wood gas. These cannot be fully utilised in the pile. If tar extraction was to be combined with the charring of the pile, small pits were made in the ground or the ground was lined with clay and the tar led out of the pile by means of a channel, and the wood vinegar was treated with iron or copper. Pipes led into a reservoir [3] [4] or wall-supported piles were built on sloping ground.
A forge is a type of hearth used for heating metals, or the workplace (smithy) where such a hearth is located. The forge is used by the smith to heat a piece of metal to a temperature at which it becomes easier to shape by forging, or to the point at which work hardening no longer occurs. The metal is transported to and from the forge using tongs, which are also used to hold the workpiece on the smithy's anvil while the smith works it with a hammer. Sometimes, such as when hardening steel or cooling the work so that it may be handled with bare hands, the workpiece is transported to the slack tub, which rapidly cools the workpiece in a large body of water. However, depending on the metal type, it may require an oil quench or a salt brine instead; many metals require more than plain water hardening. The slack tub also provides water to control the fire in the forge.
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, tiles and bricks. Various industries use rotary kilns for pyroprocessing and to transform many other materials.
Coke is a grey, hard, and porous coal-based fuel with a high carbon content. It is made by heating coal or petroleum in the absence of air. Coke is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges.
A lime kiln is a kiln used for the calcination of limestone (calcium carbonate) to produce the form of lime called quicklime (calcium oxide). The chemical equation for this reaction is
A campfire is a fire at a campsite that provides light and warmth, and heat for cooking. It can also serve as a beacon, and an insect and predator deterrent. Established campgrounds often provide a stone or steel fire ring for safety. Campfires are a popular feature of camping. At summer camps, the word campfire often refers to an event at which there is a fire. Some camps refer to the fire itself as a campfire.
A barbecue grill or barbeque grill is a device that cooks food by applying heat from below. There are several varieties of grills, with most falling into one of three categories: gas-fueled, charcoal, or electric. There is debate over which method yields superior results.
A stove or range is a device that generates heat inside or on top of the device, for local heating or cooking. Stoves can be powered with many fuels, such as electricity, natural gas, gasoline, wood, and coal.
Wood fuel is a fuel such as firewood, charcoal, chips, sheets, pellets, and sawdust. The particular form used depends upon factors such as source, quantity, quality and application. In many areas, wood is the most easily available form of fuel, requiring no tools in the case of picking up dead wood, or few tools, although as in any industry, specialized tools, such as skidders and hydraulic wood splitters, have been developed to mechanize production. Sawmill waste and construction industry by-products also include various forms of lumber tailings.
A kitchen stove, often called simply a stove or a cooker, is a kitchen appliance designed for the purpose of cooking food. Kitchen stoves rely on the application of direct heat for the cooking process and may also contain an oven, used for baking. "Cookstoves" are heated by burning wood or charcoal; "gas stoves" are heated by gas; and "electric stoves" by electricity. A stove with a built-in cooktop is also called a range.
Dry distillation is the heating of solid materials to produce gaseous products. The method may involve pyrolysis or thermolysis, or it may not.
A briquette is a compressed block of coal dust or other combustible biomass material used for fuel and kindling to start a fire. The term is a diminutive derived from the French word brique, meaning brick.
A fireplace or hearth is a structure made of brick, stone or metal designed to contain a fire. Fireplaces are used for the relaxing ambiance they create and for heating a room. Modern fireplaces vary in heat efficiency, depending on the design.
In a steam engine, the firebox is the area where the fuel is burned, producing heat to boil the water in the boiler. Most are somewhat box-shaped, hence the name. The hot gases generated in the firebox are pulled through a rack of tubes running through the boiler.
A chimney starter or charcoal chimney is a device for igniting charcoal lumps or briquettes. It consists of a metal tube with a grate to hold charcoal. A lighting cone is a similar, conical, device placed over an existing grate. The tube is typically cylindrical, but may also have other cross-sections. The tube may also be made of combustible material designed to resist burning long enough for the coals to ignite.
A beehive oven is a type of oven in use since the Middle Ages in Europe. It gets its name from its domed shape, which resembles that of a skep, an old-fashioned type of beehive.
Smokeless fuel is a type of solid fuel which either does not emit visible smoke or emits minimal amounts during combustion. These types of fuel find use where the use of fuels which produce smoke, such as coal and unseasoned or wet wood, is prohibited.
A charcoal burner is someone whose occupation is to manufacture charcoal. Traditionally this is achieved by carbonising wood in a charcoal pile or kiln. Charcoal burning is one of the oldest human crafts.
The lò trấu is a type of versatile fuel burning cook stove used in Vietnam since the 1950s. Lò trấu comes from lò (stove) and trấu. A kitchen with this kind of stove is a bếp trấu, "husk kitchen."
A wood-burning stove is a heating or cooking appliance capable of burning wood fuel, often called solid fuel, and wood-derived biomass fuel, such as sawdust bricks. Generally the appliance consists of a solid metal closed firebox, often lined by fire brick, and one or more air controls. The first wood-burning stove was patented in Strasbourg in 1557. This was two centuries before the Industrial Revolution, so iron was still prohibitively expensive. The first wood-burning stoves were high-end consumer items and only gradually became used widely.
Charcoal is a lightweight black carbon residue produced by strongly heating wood in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern charcoal briquettes used for outdoor cooking may contain many other additives, e.g. coal.
{{cite web}}: CS1 maint: bot: original URL status unknown (link) (PDF; 1.25 MB), at 750jahrewolfwil.ch, retrieved 14 August 2016.
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