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Kinetic approach when calculating parameters of fire-and-explosion hazard of gas mixes of methane with chlorine

Journal: Pozharovzryvobezopastnost/Fire and Explosion Safety (Vol.27, No. 2)

Publication Date:

Authors : ;

Page : 27-36

Keywords : ;

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Abstract

Purpose. The computational method of indexes of fire-and-explosion hazard of gas mixtures a kinetics and the mechanism of chemical interaction which is based on a heat conduction equation and considering is considered. This method allows to define indicators of fire-and-explosion hazard of substances which can enter among themselves chemical reaction. That methods where for definition of indexes of fire-and-explosion hazard of substances use a structure of molecules do not allow and can be applied only to one homologous series. Methods. Calculation of indicators of fire-and-explosion hazard was carried out by means of the mathematical model of thermal ignition developed by authors in the environment of MATLAB. Researches were conducted for gas mixes of methane, chlormethane and dichloromethane with chlorine at ignition of these mixes heat and ultra-violet light, in a cylindrical vessel of long 0.04 m, with a diameter of 0.036 m. For creation of model the chemical kinetics of elementary reactions of these mixes is considered. Coefficients of heat conductivity and thermal capacity for initial composition of mix paid off, and during chemical transformations considered their change from temperature. Results of calculation were compared to experimental data. Findings. By means of model of thermal ignition for mixes of methane, chlormethane and dichloromethane with chlorine concentration limits of photoignition and critical intensity of ultra-violet light have been set. For chlormethane mix with chlorine the minimum phlegmatizing concentration of four-chloride carbon is defined, and for methane with chlorine spontaneous ignition temperature is calculated. Results of calculation of indicators of fire-and-explosion hazard for these mixes enough with a good accuracy coincide with experimental data. Conclusions. The model of thermal ignition which is based on the equation of heat conductivity and considering kinetics and the mechanism of chemical reaction authentically reflects a physical picture of ignition and gives the chance for chlorine mixes with methane and its chlorderivatives to estimate such parameters as: concentration limits of photoignition, critical intensity of UV-light, minimum phlegmatizing concentration and temperature of spontaneous ignition. This method has shown a possibility of calculation of indicators of fire-and-explosion hazard of gas substances for kinetic data on the mechanism of chemical interaction and to constants of speed of elementary reactions.

Last modified: 2018-10-16 21:47:27