DIFFUSION COMBUSTION OF LIQUEFIED NATURAL GAS. BURNOUT RATE AND FLAME SIZE

Исследование направлено на изучение параметров горения сжиженного природного газа (СПГ), необходимых для оптимального выбора средств обеспечения пожарной безопасности при его производстве, хранении, транспортировке и использовании. Актуальность данной работы связана с существенным ростом масштабов производства и использования СПГ, являющегося одним из важнейших средств обеспечения энергобезопасности страны и ее конкурентоспособности на внешнем рынке.
 The study is devoted to investigation in the size of the flames of liquefied natural gas (LNG). A detailed analysis of accidents at LNG storage and processing facilities shows the potential dangers arising from its use, as well as the relevance of their scientific study. The data on the fires that have occurred, presented in the scientific literature, indicate that the height of the flame of flammable liquids (including liquefied gases) depends largely on the rate of burnout and the typical size of the spill area (side of the square, diameter), as a rule, limited by the dike. The empirical Thomas equation for determining the dimensionless flame height of flammable liquids is given in the scientific literature. The proposed dependence summarizes the data on the size of the flames of the following series of flammable liquids: gasoline, hexane, methanol. The application of this dependence to generalize the available literature data on the size of LNG flames undertaken by domestic authors showed that the calculated and experimental data differ by about 3 times. According to the authors of such an assessment, the difference indicates that the Thomas equation is not optimal for a reliable estimation of the size of LNG flames, which differ significantly in their physicochemical properties from known combustible liquids. Considering this, as well as the fact that the burnout rate depends to varying degrees on many factors (evaporation area, surface type, thickness of the combustible liquid layer, etc.), the most reliable data can be obtained by direct experiments which results are provided in this paper. Based on the results of the experiments, a comparative assessment of the dimensionless height of the flame, measured in experiments when burning LNG in steel baking trays and a concrete bath, was carried out with calculations according to the Thomas formula. In this formula, the density of the LNG vapor phase directly above the combustible liquid layer was used to estimate the burnout rate. A graphical representation of the experimental results and the calculated ones (according to the Thomas formula) using the vapor phase density parameter showed that the generalization of the literature and the present experimental data gives a more reliable result. According to the results of the study, we can conclude about the possibility of using the data obtained for design estimates of the size of LNG flames and the feasibility of further large-scale studies to obtain more complete information.