Activated carbon ignition

Activated carbon ignites immediately in the gas, mixtures with methane ignite, and those with carbon monoxide ignite on warming, while those with hydrogen explode on heating or sparking. 

Ignition Activated carbons ignite at lower temperature than oxide carriers. Activated carbons show an ignition temperature of about 200°C (chemical activated carbons) up to 500°C (steam activated carbons). This characteristics is used advantageously by burning the carrier to reclaim the precious metal. 

The low autoignition temperature of benzaldehyde (192°C) presents safety problems since benzaldehyde can be ignited by exposure to low pressure steam piping, for example. Benzaldehyde may also spontaneously ignite when soaked into rags or clothing or adsorbed onto activated carbon (13). 

Ignition Temperature of Granular Activated Carbon Carbon Tetrachloride Activity of Activated Carbon Ball-Pan Hardness of Activated Carbon... 

According to the National Board of Fire Underwriters, activated carbons normally used for water treatment pose no dust explosion ha2ard and are not subject to spontaneous combustion when confined to bags, dmms, or storage bins (64). However, activated carbon bums when sufficient heat is appbed the ignition point varies between about 300 and 600°C (65). 

It was not nndl the 1950s that detonation flame arresters made of crimped metal ribbon elements were developed and began to be used more freqnendy (Binks 1999). The major impetus for die use of crimped metal ribbon detonation flame arresters in the US was the enactment of clean air legislation (Clean Air Act of 1990) which inadvertently created a safety problem by requiring reductions in volatile organic compound (VOC) emissions. To do this, manifolded vent systems (vapor collection systems) were increasingly installed in many chemical process industry plants which captured VOC vapors and transported them to suitable recovery, recycle, or destruction systems. This emission control requirement has led to the introdnction of ignition risks, for example, from a flare or via spontaneous combustion of an activated carbon adsorber bed. Multiple... 

The installation of flame arresters shonld also be considered for vacnnm pnmps, activated carbon adsorbers, etc. which emit flammable vapors and/or can serve as ignition sonrces. 

Activated carbon showed an auto-ignition temperature in flowing air of 452-518°C. Presence of 5% of the base ( triethylenediamine ) adsorbed on the carbon reduced the AIT to 230-260°C. At high air flow rates an exotherm was seen at 230-260°, but ignition did not then occur until 500°C. 

Unsaturated (drying) oils, like linseed oil, etc., will rapidly heat and ignite when distributed on active carbon, owing to the enormous increase in surface area of the oil exposed to air, and in the rate of oxidation, probably catalysed by metallic impurities [1]. A similar, but slower, effect occurs on fibrous materials such as cotton waste [2],... 

In the absence of other ignition source), fires in plant to recover acetone from air with active carbon are due to the bulk surface effect of oxidative heating when air flow is too low to cool effectively. 

Mellor, 1941, Vol. 2, 292 1956, Vol. 2, Suppl. 1, 380 1943, Vol. 11, 26 Liquid chlorine at —34°C explodes with white phosphorus, and a solution in heptane at 0°C ignites red phosphorus. Boron, active carbon, silicon and phosphorus all ignite in contact with gaseous chlorine at ambient temperature. Arsenic incandesces on contact with liquid chlorine at —34°C, and the powder ignites when sprinkled into the gas at ambient temperature. Tellurium must be warmed slightly before incandescence occurs. 

Nonmetals. Boron, activated carbon, silicon, and phosphorus ignite in gaseous chlorine.14,21,28... 

The body of evidence points to the oxidation of the flammable material (condensed fumes) on activated carbon as the ignition source. There is no doubt that cooler evening temperatures caused the vapors in the tanks to contract. Air was drawn into the drums. Autoignition of the turpentine on carbon occurred and the resulting flame traveled back to the tanks. [11,12]... 

Potentially explosive reaction with nitric acid + sulfuric acid, bromine trifluoride, nitrosyl chloride + platinum, nitrosyl perchlorate, chromyl chloride, thiotrithiazyl perchlorate, and (2,4,6-trichloro-l, 3,5-triazine + water). Reacts to form explosive peroxide products with 2-methyl-1,3-butadiene, hydrogen peroxide, and peroxomonosulfuric acid. Ignites on contact with activated carbon, chromium trioxide, dioxygen difluoride + carbon dioxide, and potassium-tert-butoxide. Reacts violendy with bromoform, chloroform + alkalies, bromine, and sulfur dichloride. 

Ignition or explosive reaction with metals (e.g., aluminum, antimony powder, bismuth powder, brass, calcium powder, copper, germanium, iron, manganese, potassium, tin, vanadium powder). Reaction with some metals requires moist CI2 or heat. Ignites with diethyl zinc (on contact), polyisobutylene (at 130°), metal acetylides, metal carbides, metal hydrides (e.g., potassium hydride, sodium hydride, copper hydride), metal phosphides (e.g., copper(II) phosphide), methane + oxygen, hydrazine, hydroxylamine, calcium nitride, nonmetals (e.g., boron, active carbon, silicon, phosphoms), nonmetal hydrides (e.g., arsine, phosphine, silane), steel (above 200° or as low as 50° when impurities are present), sulfides (e.g., arsenic disulfide, boron trisulfide, mercuric sulfide), trialkyl boranes. 

Pr P., Delage F. and Le Cloirec P., Modeling the exothermal nature of V.O.C adsorption to prevent activated carbon bed ignition. Fundamentals of adsorption 7, K. Kaneto, H. Kanoh, Y. Hanzawa Editors, IK International, Chiba, Japon, (2001) pp. 700 -707. 

Interactions with the carbon surface can make the recovery of certain solvents, such as ketones and chlorinated hydrocarbons, difficult. Ketones and aldehydes can polymerize, releasing large amounts of heat. When this happens in a part of the bed with poor heat transfer, the temperature can reach the ignition point of the solvent. Fires always start with hot-spots in parts of the bed where the airflow is reduced due to poor design. The susceptibility of the carbon bed to autoignition can be reduced by removing soluble alkali sodium and potassium salts, that may be present as impurities in the activated carbon and which can function as combustion and gasification catalysts [29]. 

The steady interest in the effects of the chemistry and physics of the carbon surface on pollutant removal from waters has been ignited by the U.S. Clean Water Act (enacted in 1972, amended as the Water Quality Act in 1987). The most recent interest stems from the Safe Drinking Water Act Amendment of 1996. Activated carbon adsorption has been cited by the U.S. Environmental Protection Agency (www.epa.gov) as one of the best available control technologies. Furthermore, the most recent efforts to understand the adsorption of the same pollutants by soils [7,8] can benefit from comparisons of similarities and differences with respect to the behavior of activated carbons. 

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