Influence of temperature and time upon pyrolysis of untreated and fire retardant treated wood

Knudson, Robert; Williamson, R. B.

doi:10.1007/bf00353680

Cited by 11 publications

(5 citation statements)

References 2 publications

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“…The tabled 5 percent F value is 3.26. Because calculated F values are less than the tabulatedFvalues, this reduced model is clearly acceptable for five slabs (20,22,32,35,39), not acceptable for one slab (43), and marginal for two slabs (3,33). We concluded that overall the reduced model was acceptable for Equation (2).…”

Section: Time-location Modelsmentioning

confidence: 76%

Charring rate of wood for ASTM E 119 exposure

1992

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Analytical methods that predict the endurance of structural wood members in a fire are based on the reduction of the cross section of the member caused by wood being charred. To define the charring rate in terms of more fundamental properties, empirical models were established. Eight species were tested for charring rates and material properties. Regression analysis was used to develop the models. The predictor variables for the initial factorial design included density, moisture content, treatability, and hardwood-softwood classification. The addition of char contraction simplified the model and reduced the predictor variables to the char contraction factor, density, and moisture content. Our results show the importance of surface recession and moisture content to wood charring.

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Section: Time-location Modelsmentioning

confidence: 76%

Charring rate of wood for ASTM E 119 exposure

1992

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“…11); however, the middle lamella and primary cell walls are the first cell wall components to form, and are the first to become lignified, therefore the middle lamella has a substantially higher concentration of lignin than the secondary wall (Christiernin ). The pyrolysis of lignin begins at lower temperatures than cellulose, and at a slower rate, and continues to much higher temperatures (Tang ; Knudson & Williamson ; Yang et al . ) meaning that the lignin‐rich components of the cell wall pyrolyse at different rates.…”

Section: Discussionmentioning

confidence: 99%

Observations of the structural changes that occur during charcoalification: implications for identifying charcoal in the fossil record

Hudspith

Belcher

2017

Palaeontology

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All of our current understanding of fossil charcoal structure comes from observations of modern wood charcoal produced in furnaces. These charcoals consistently show cell wall homogenization after prolonged heating (>325°C) and this is therefore considered to be a key identifying feature of fossil charcoal. Yet furnaces are unable to replicate the full combustion processes that occur during a wildfire. Here, for the first time, we have studied the microscopic structural evolution of charcoal produced using calorimetry, wherein the wood is ignited under controlled conditions and the heat release rate and other parameters measured, and the resulting charcoal studied using reflected light microscopy. We show that homogenization of cell walls is actually only a short-lived phase of charcoal formation that occurs during the early heating stages as the pyrolysis front traverses through the wood. Cell wall homogenization is then rapidly overprinted by the thinning, distortion and breakdown of cell walls, and a notable visual increase in reflectance. Our preliminary study therefore suggests that we need to first improve our understanding of charcoal formation in order to better understand the fossil record of wildfires.

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“…No morphological studies have been found for the hemicelluloses and holocelluloses or lignin during pyrolysis. Knudson and Williamson (1971) observed morphological changes in wood heated in air.…”

Section: Morphology Of Biomass During Pyrolysismentioning

confidence: 96%

Survey of Biomass Gasification, Volume II: Principles of Gasification

Reed

1979

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Air gasification, while requiring a pyrolytic step, uses a minimal quantity •of air and steam to convert the char to gas in a single unit. Air gasification of biomass is particularly simple, and about a million air gasifiers were built during World War n.to operate cars and trucks or generate power. The gas produced is called "low energy gas" (LEG) because it is diluted by the nitrogen of the air. While not suitable for pipeline distribution, it can be used in retrofitting existing boilers now using oil or natural gus, as well as to drive engines for transportation or power generation.

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Influence of temperature and time upon pyrolysis of untreated and fire retardant treated wood

Cited by 11 publications

References 2 publications

Charring rate of wood for ASTM E 119 exposure

Charring rate of wood for ASTM E 119 exposure

Observations of the structural changes that occur during charcoalification: implications for identifying charcoal in the fossil record

Survey of Biomass Gasification, Volume II: Principles of Gasification

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