Charring: Difference between revisions

Content deleted Content added

Inline

Latest revision as of 23:53, 9 November 2024

Charring is a chemical process of incomplete combustion of certain solids when subjected to high heat. Heat distillation removes water vapour and volatile organic compounds (syngas) from the matrix. The residual black carbon material is char, as distinguished from the lighter colored ash. By the action of heat, charring removes hydrogen and oxygen from the solid, so that the remaining char is composed primarily of carbon.^[1] Polymers like thermoset, or most solid organic compounds like wood or biological tissue, exhibit charring behaviour. In non-scientific terms, charring means partially burning so as to blacken the surface.^[1]

Charring can result from naturally occurring processes like fire; it is also a deliberate and controlled reaction used in the manufacturing of certain products. The mechanism of charring is part of the normal burning of certain solid fuels like wood. During normal combustion, the volatile compounds created by charring are consumed at the flames within the fire or released to the atmosphere, while combustion of char can be seen as glowing red coals or embers which burn without the presence of flames.

Production of char

An aerial view of a bearded man in a coat, with a handmade rake, standing on a low, ~10m wide, rounded mound of black earth. The mound is emitting many slender streamers of smoke from all of its surface except the bottommost meter. The steamers merge and stream diagonally away from the viewer on a gentle but chill morning breeze, making an opaques white cloud. The visible background is dark coniferous forest; in the foreground, a glimps of another pile, this one tightly packed wood not yet covered with soil. — A charcoal burner tending his charcoal clamp, in which he is producing charcoal. The process takes days, and the clamp has to be monitored to stop the fire from breaking out (technically, the oxygen from breaking in).

Coke and charcoal are both produced by charring, whether on an industrial scale or through normal combustion of coal or wood. Normal combustion consumes the char as well as the gases produced in its creation, while industrial processes seek to recover the purified char with minimal loss to combustion. This is accomplished by either burning the parent fuel (wood or coal) in a low-oxygen environment or by heating it to a high temperature without allowing combustion to occur. In industrial production of coke and charcoal, the volatile compounds driven off during charring are often captured for use in other chemical processes.

A "coal burning" blacksmith's forge actually produces the heat necessary for high-temperature metalworking by the continuous production and consumption of coke within a carefully managed fire. An inner ring of burning coke provides heat which converts the encircling coal into coke, which is then itself fed into the center of the fire to provide the required heat and to create more coke; coal itself is incapable of producing the heat required for some blacksmithing operations.

Charring and fire protection

Charring is an important process in the combustion ignition of solid fuels and in smouldering. In construction of heavy-timbered wood buildings the predictable formation of char is used to determine the fire rating of supporting timbers and is an important consideration in fire protection engineering. If a wood column is of large enough diameter, during a structure fire its exposed surface will be converted to char until the thickness of char provides sufficient insulation to prevent additional charring. This layer then serves to protect the remaining structurally sound core of wood, which can continue to carry the building loads if appropriately designed. ^{[citation needed]}

Traditional houses in Naoshima, Kagawa clad with *yakisugi* panels

Wood preservation

Charring is also a technique used for wood preservation. In Japan this traditional technique is called yakisugi or shō sugi ban.^[2]

Legal definitions

Charring had a special meaning under the common law of England. Under that system, the crime of arson required charring of a dwelling—actual damage to the fiber of the material from which the structure was built—and not mere "scorching" or damage to the surface, or to surface coverings such as carpets and wallpaper.

References

^ ^a ^b "charring". TheFreeDictionary.com. Retrieved 2019-01-11.
^ "The value in charring wood surfaces goes beyond visual effect". The Globe and Mail. 2017-06-19. Retrieved 2019-01-11.

[TheFreeDictionary.com-1] "charring". TheFreeDictionary.com. Retrieved 2019-01-11.

[The_Globe_and_Mail_2017-2] "The value in charring wood surfaces goes beyond visual effect". The Globe and Mail. 2017-06-19. Retrieved 2019-01-11.

[1]

[2]

@@ Line 1: / Line 1: @@
+{{Short description|Chemical process}}
-'''Charring''' is a chemical process of incomplete [[combustion]] of certain solids when subjected to high [[heat]].  The resulting residue matter is called [[char]].  By the action of heat, charring removes [[hydrogen]] and [[oxygen]] from the solid, so that the remaining char is composed primarily of [[carbon]].<ref name="TheFreeDictionary.com"/> Polymers like [[thermoset]], or most solid organic compounds like wood or [[biological tissue]], exhibit charring behaviour.<ref name="ScienceDirect">{{cite web | title=ScienceDirect | website=ScienceDirect | url=https://www.sciencedirect.com/topics/earth-and-planetary-sciences/charring | access-date=2019-01-11}}</ref>
+'''Charring''' is a chemical process of incomplete [[combustion]] of certain solids when subjected to high [[heat]]. Heat distillation removes [[water vapour]] and [[volatile organic compound]]s ([[syngas]]) from the matrix. The residual [[black carbon]] material is [[Char (chemistry)|char]], as distinguished from the lighter colored [[ash]]. By the action of heat, charring removes [[hydrogen]] and [[oxygen]] from the solid, so that the remaining char is composed primarily of [[carbon]].<ref name="TheFreeDictionary.com"/> Polymers like [[thermoset]], or most solid organic compounds like wood or [[biological tissue]], exhibit charring behaviour. In non-scientific terms, charring means partially burning so as to blacken the surface.<ref name="TheFreeDictionary.com">{{cite web | title=charring | website=TheFreeDictionary.com | url=https://www.thefreedictionary.com/charring | access-date=2019-01-11}}</ref>
+Charring can result from naturally occurring processes like fire; it is also a deliberate and controlled reaction used in the manufacturing of certain products. The mechanism of charring is part of the normal burning of certain solid fuels like wood. During normal combustion, the volatile compounds created by charring are consumed at the flames within the fire or released to the atmosphere, while combustion of char can be seen as glowing red coals or embers which burn without the presence of flames.
-Charring means partially burning so as to blacken the surface.<ref name="TheFreeDictionary.com">{{cite web | title=charring | website=TheFreeDictionary.com | url=https://www.thefreedictionary.com/charring | access-date=2019-01-11}}</ref>
+==Production of char==
-Charring can result from naturally occurring processes like fire; it is also a deliberate and controlled reaction used in the manufacturing of certain products. The mechanism of charring is part of the normal burning of certain solid fuels like wood. During normal combustion, the volatile compounds created by charring are consumed at the flames within the fire or released to the atmosphere, while combustion of char can be seen as glowing red coals or embers which burn without the presence of flames.<ref name="ScienceDirect"/>
+[[File:Adam_ne_yap%C4%B1yor(k%C3%B6m%C3%BCr_yap%C4%B1yor)_-_panoramio.jpg|thumb|left|alt=An aerial view of a bearded man in a coat, with a handmade rake, standing on a low, ~10m wide, rounded mound of black earth. The mound is emitting many slender streamers of smoke from all of its surface except the bottommost meter. The steamers merge and stream diagonally away from the viewer on a gentle but chill morning breeze, making an opaques white cloud. The visible background is dark coniferous forest; in the foreground, a glimps of another pile, this one tightly packed wood not yet covered with soil.|A [[charcoal burner]] tending his charcoal clamp, in which he is producing [[charcoal]]. The process takes days, and the clamp has to be monitored to stop the fire from breaking out (technically, the oxygen from breaking in).]]
+[[Coke (fuel)|Coke]] and [[charcoal]] are both produced by charring, whether on an industrial scale or through normal combustion of coal or wood. Normal combustion consumes the char as well as the gases produced in its creation, while industrial processes seek to recover the purified char with minimal loss to combustion. This is accomplished by either burning the parent fuel (wood or coal) in a low-oxygen environment or by heating it to a high temperature without allowing combustion to occur. In industrial production of coke and charcoal, the volatile compounds driven off during charring are often captured for use in other chemical processes.
+A "coal burning" [[blacksmith|blacksmith's]] [[forge]] actually produces the heat necessary for high-temperature [[metalworking]] by the continuous production and consumption of coke within a carefully managed fire. An inner ring of burning coke provides heat which converts the encircling coal into coke, which is then itself fed into the center of the fire to provide the required heat and to create more coke; coal itself is incapable of producing the heat required for some blacksmithing operations.
-== Production of char ==
-[[File:Adam_ne_yap%C4%B1yor(k%C3%B6m%C3%BCr_yap%C4%B1yor)_-_panoramio.jpg|thumb|left|alt=An aerial view of a bearded man in a coat, with a handmade rake, standing on a low, ~10m wide, rounded mound of black earth. The mound is emitting many slender streamers of smoke from all of its surface except the bottommost meter. The steamers merge and stream diagonally away from the viewer on a gentle but chill morning breeze, making an opaques white cloud. The visible background is dark coniferous forest; in the foregroud, a glimps of another pile, this one tightly-packed wood not yet covered with soil.|A [[charcoal burning|charcoal-burner]] tending his charcoal clamp, in which he is producing [[charcoal]]. The process takes days, and the clamp has to be monitored to stop the fire from breaking out (technically, the oxygen from breaking in).]]
-[[Coke (fuel)|Coke]] and [[charcoal]] are both produced by charring, whether on an industrial scale or through normal combustion of coal or wood. Normal combustion consumes the char as well as the gases produced in its creation, while industrial processes seek to recover the purified char with minimal loss to combustion. This is accomplished by either burning the parent fuel (wood or coal) in a low-oxygen environment or by heating it to a high temperature without allowing combustion to occur. In industrial production of coke and charcoal the volatile compounds driven off during charring are often captured for use in other chemical processes.
+==Charring and fire protection==
-A "coal burning" [[blacksmith|blacksmith's]] [[forge]] actually produces the heat necessary for high-temperature [[metalworking]] by the continuous production and consumption of coke within a carefully managed fire.  An inner ring of burning coke provides heat which converts the encircling coal into coke, which is then itself fed into the center of the fire to provide the required heat and to create more coke; coal itself is incapable of producing the heat required for some blacksmithing operations.
+Charring is an important process in the combustion ignition of solid [[fuels]] and in [[smouldering]]. In construction of heavy-timbered wood buildings the predictable formation of char is used to determine the [[fire rating]] of supporting timbers and is an important consideration in [[fire protection]] engineering. If a wood column is of large enough diameter, during a structure fire its exposed surface will be converted to char until the thickness of char provides sufficient insulation to prevent additional charring. This layer then serves to protect the remaining structurally sound core of wood, which can continue to carry the building loads if appropriately designed. {{Citation needed|reason=There appears to be some contradictory evidence in peer reviewed scientific publications regarding whether (1) char formation is predictable, (2) in some cases char has been shown to fall off, exposing fresh timber which then becomes involved in the fire. Perhaphs this section should be expanded to show the complexity of the topic.|date=April 2020}}
-== Charring and fire protection ==
-Charring is an important process in the combustion ignition of solid [[fuels]] and in [[smouldering]].  In construction of heavy-timbered wood buildings the predictable formation of char is used to determine the [[fire rating]] of supporting timbers and is an important consideration in [[fire protection]] engineering.  If a wood column is of large enough diameter, during a structure fire its exposed surface will be converted to char until the thickness of char provides sufficient insulation to prevent additional charring.  This layer then serves to protect the remaining structurally sound core of wood, which can continue to carry the building loads if appropriately designed.
 [[File:Art House Project03s3872.jpg|thumb|Traditional houses in [[Naoshima, Kagawa]] clad with ''yakisugi'' panels]]
-== Wood preservation ==
-Charring is also a technique used for [[wood preservation]]. In Japan this traditional technique is called ''[[yakisugi]]'' or ''shō sugi ban''.<ref name="The Globe and Mail 2017">{{cite web | title=The value in charring wood surfaces goes beyond visual effect | website=The Globe and Mail | date=2017-06-19 | url=https://www.theglobeandmail.com/life/home-and-garden/decor/the-value-in-charring-wood-surfaces-goes-beyond-visual-effect/article16235588/ | access-date=2019-01-11}}</ref>
+==Wood preservation==
-== Legal definitions ==
+Charring is also a technique used for [[wood preservation]]. In Japan this traditional technique is called ''[[yakisugi]]'' or ''shō sugi ban''.<ref name="The Globe and Mail 2017">{{cite news | title=The value in charring wood surfaces goes beyond visual effect | website=The Globe and Mail | date=2017-06-19 | url=https://www.theglobeandmail.com/life/home-and-garden/decor/the-value-in-charring-wood-surfaces-goes-beyond-visual-effect/article16235588/ | access-date=2019-01-11}}</ref>
+==Legal definitions==
 Charring had a special meaning under the [[common law]] of [[England]]. Under that system, the crime of [[arson]] required charring of a dwelling—actual damage to the fiber of the material from which the structure was built—and not mere "scorching" or damage to the surface, or to surface coverings such as carpets and wallpaper.
-== See also ==
+==See also==
-*[[Charcoal]]
+*[[Gasification]]
 *[[Pyrolysis]]
 ==References==
-{{reflist}}
+{{Reflist}}
 [[Category:Chemical processes]]