Flame Safety and the Parameters that Affect Them

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Title Flame Safety and the Parameters that Affect Them
Creator Pohl, J.H.
Contributor Gogolek, P.E.G., Seebold, J.G.
Date 2015-09-11
Spatial Coverage Salt Lake City, Utah
Subject 2015 AFRC Industrial Combustion Symposium
Description Paper from the AFRC 2015 conference titled Flame Safety and the Parameters that Affect Them
Abstract Industry needs to keep flames lit and stable to to transfer heat and provide the heat that safely manufacturers products. The safety of gases depend on a number of factors of which most are tabulated in standard references. These factors include conditions of the flame, such as temperature, pressure, combustion properties of the gases, and oxygen concentration. A number of parameters that control flame performance are tabulated from small scale data. There are also methods to estimate most of these parameters from empirical relationships for gas mixtures.; The first parameter is the heating value of the gases. The heating values of gases and liquids are tabulated. However, Hoyt Hottel (deceased) and others developed a technique to estimate the heating value of a wide range of gases using the energy of individual bonds. The heating value of gas mixtures can be estimated by combining the heating value of the gas mixtures based on composition and subtracting the energy of the bonds formed.; The next parameter is the ignition temperature. This is the minimum temperature required to ignite the fuel-air mixture. It is measured at small scale by subjecting gas mixtures to increasing temperatures in a coated vessel until the mixture ignites.; The minimum ignition energy is another parameter. It is the minimum amount of energy that must be applied to a gas mixtures in a coated vessel to ignite the mixture. This includes the quench space required for ignition. The value of minimum energy to ignite gas mixtures and dead spaces are tabulated in standard reference sources.; The third parameter is the flammability limits. The lower limit is a lower (lowest level of fuel in air or oxygen) and Upper Level (highest level of fuel in air) at which the flame ignites and burns in a coated vessel. The flammability limits of gas mixtures can be accessed from graphs or tabulations of the Flammability Limits. The flammability limits of mixtures can be estimated using Le Chatelier's Rule. The final parameter is the flame speed (rate of reaction of the gases that comprise the flame), it is also tabulated and can be measured at small scale by several techniques. The simplest way is to measure the velocity at which a flat flame can be blown-off. The accuracy of the flame speed measurement can be improved by reducing the pressure of the flame. The flame speed must be higher than the imposed velocity to maintain flame stability. A method has been developed by the US Bureau of Mines to estimate the flame speed of gas mixtures.
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ARK ark:/87278/s69k8n6r
Setname uu_afrc
Date Created 2018-11-30
Date Modified 2018-11-30
ID 1387827
Reference URL https://collections.lib.utah.edu/ark:/87278/s69k8n6r