BUILD MONOCYTOGENES MODELS FOR CALCULATION OF THE BENZ(A)PYRENE CONTENTIN THE FLUE GAS OF COAL-FIRED BOILERS
Keywords:
benz(a)pyrene, toxicity, carbon monoxide, combustionAbstract
The article is devoted to the construction of computational techniques determination of content of benz(a)pyrene in the combustion products of coal-fired boilers on the basis of monocytogenes model. The increase in the intensity of mixing and burning fuel reduces output of the entire group of polycyclic aromatic hydrocarbons, including benz(a)pyrene. Adjustment to low-emission modes of the boiler is only possible with the availability of reliable methods for the determination of the concentration of benz(a)pyrene in flue gases. Despite the low level of the mass emissions of benz(a)pyrene it is necessary to consider its contribution to the overall toxicity of flue gases. When burning coal fuel effect of the degree of metamorphism of fuel on the total yield of products of incomplete combustion appears to be more significant compared to combustion of natural gas or fuel oil. The temperature in the zone of active combustion is an integral indicator of the combustion process and affects the intensity and mechanism of formation of polycyclic aromatic hydrocarbons in the combustion products. Because along with the concentration of carbon monoxide the content of benz(a)pyrene in the combustion products is an indicator of the chemical incompleteness of combustion of hydrocarbon fuel. Carbon monoxide indirectly characterizes the content of benz(a)pyrene in exhaust gases. It is shown that the formation of triatomic gases in the combustion chamber of a pulverized coal boiler results in increasing the content of carbon monoxide in the combustion products and the creation of favorable conditions for intense generation of benz(a)pyrene. Taking into account the initial working composition of the fuel allows a more reliable estimate of the content of benz(a)pyrene in exhaust gases of solid-fuel boilers. It is revealed that the degree of conversion of the group of polyaromatic hydrocarbons, including benz(a)pyrene in combustion of coal as a fuel in this case is negligible, since the concentration of benz(a)pyrene varies in a narrow range. In these terms, the content of carbon monoxide varies in a wide interval of values. Numerical analysis of the obtained results showed that in the case of using the calculated dependency to determine the concentration of benz(a)pyrene in products of combustion the dominant contribution to the evaluation mechanism and make the initial parameters of formation and growth of nuclei smoke particles and benz(a)pyrene in the examined range of values of carbon monoxide. It is established that the weaker are the effects of operating parameters of combustion, it is necessary to note the important role of concentration level of oxygen in initial and final moments of burning pulverized coal mixture. At the beginning of the combustion process, the oxygen participates in the formation of the fuel-air mixture, and in the end contributes to the afterburning of products of incomplete combustion. Revealed that the greatest degree of conversion of polycyclic aromatic compounds in the case under consideration meets the minimum content of benz(a)pyrene or maximal concentration of carbon monoxide in the combustion products.
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