Розвиток наукових основ прогнозування параметрів пожежовибухонебезпечності вуглеводнів та їх похідних

Abstract

The dissertation is devoted to the solution of an actual scientific and applied problem in the fire safety field – the development of scientific foundations for predicting fire and explosion hazard parameters of hydrocarbons and their derivatives. Despite the practical importance of this scientific activity direction, it is usually carried out using approximation methods with significant errors. The unsatisfactory state of solving the identified problem necessitated the need for this scientific work. The levels analysis of substance physicochemical properties formation showed that modern calculation methods do not take into account the supramolecular structure level. The aim of the work is to develop scientifically based approaches to predicting the substances parameters of combustion initiation and extinguishing, taking into account their supramolecular structure. The object of the study is the fire and explosion hazard of the hydrocarbons and their derivatives main classes, and the subject is the physicochemical parameters influence on it. The following main results are obtained in solving the scientific problem. Existing correlations for substance parameters with the carbon atoms number in the molecule and between similar parameters for homologous series of n-alkanes and n-alcohols are established. Based on the melting temperatures oscillation, organic substances supramolecular structures modeling in the clusters form is carried out. For most n-alkanes, the dimer structure (methane – hexamer, ethane – trimer) with the alternating clustering site in the molecule worked. On this basis and on the assumption that clusters of the same length and molar mass will have the same melting point is developed an indicator of "melting ease" and a formula for calculating the melting point, which works for the modeling hydrocarbons of different homologous series. For solubility in water, in addition to the clusters length, the associated water molecules number by one hydrocarbon molecule is taken into account. A method for the liquids flash point calculating of different homologous series is developed, which works with R = 0,996. A method for calculating the temperature limits and the flash point of liquid mixtures based on the adaptation of Raoult's and Dalton's laws for saturated vapor pressures is developed; also – for mixtures of flammable liquids and water, the criterion for non-flammability of such mixture and the method for estimating the self-phlegmatization temperature point of the vapor phase is developed. Formulas is developed to predict the combustible air mixtures minimum ignition energy based on the smallest explosive gap and ambient temperature, as well as for the ignition source saturation energy. The equations system is developed that describes the change in FL due to changes in the temperature and in case of the ignition source energy, that lower, then saturation energy. A new method of determining the hydrocarbons average length for calculating the autoignition temperature with indirect consideration of the totality of mesomeric and inductive effects of the electron density redistribution by molecular length is developed. A new universal calculated dependence for determining the autoignition temperature is developed, while the molecule average length indirectly takes into account supramolecular structures. A device is developed for differential thermal analysis in a single-chamber system. A method for predicting the solid materials propensity to thermal spontaneous combustion is developed based on the indicators in the experiment. The relationship between the solid materials propensity to spontaneous combustion and their aerosols explosion hazard is established, which indicates the clustering processes determining role in combustion processes based on the peroxide mechanism. In the n-alkanes homologous series the oscillations have the following fire hazard parameters: normal flame propagation speed, area width of FL, change flash point acceleration, autoignition temperature. To explain this, the work assumes the peroxide complexes presence during the initiation and propagation of combustion. For the explosion is proposed – a cooperative process of the supramolecular structure field self-organization followed by this structure decomposition. Two mechanisms of hydrocarbon molecules clustering with air oxygen are provided: at low pressures – immediate association with oxygen molecules; at high pressures – first clustering of several molecules of the combustible substance, and then with air oxygen. The combustion initiation moment is considered as the gaseous solution formation of a combustible substance in oxygen with the peroxide complex compounds formation that have a higher molar mass and the ability to the condense. Alkanes peroxide clusters lengths modeling for the describe autoignition is carried out. Approximation formulas is developed based on the "ease of melting" modified index for predicting autoignition temperatures and the anti-knock index of n-alkanes; also – a propensity indicator to detonation, which allows to separate explosive and non-explosive combustible substances by calculation and predict the explosive substances detonation speed. The peroxide stoichiometric proportions modeling of the certain clusters formation in combustible substances air mixtures, which determine the initiation critical limits of combustion various types and which are still sufficient for the continuous supramolecular structures formation of a certain type, is proposed and carried out. Phase transitions characteristic temperatures of proposed supramolecular structures are evaluated and the condensation processes possibility in the flame front preparatory zone is shown. It is shown that the simplest way to stop the liquids burning is to reduce the evaporation intensity, which can be achieved by cooling or isolating the surface to ensure the required evaporation retardation factor. The foam glass-based floating system use for fire extinguishing to polar and non-polar liquids is investigated: covering foam glass with gel improves isolation, and wetting with water improves cooling properties. The isolating and cooling properties of such systems, combustion stopping modes in case of their application to the surface of polar and non-polar liquids is found out. A formula is developed that, based on the flash point value, predicts the fire-extinguishing layer thickness of the foam glass for various systems of its application. With the greatest accuracy, the fire-extinguishing layer of dry foam glass is approximated by the cluster equivalent length parameter.