FIELD: chemistry; measurement.
SUBSTANCE: invention relates to methods of measuring weight loss of hydrocarbons during preparation and transportation of oil at oil fields and at enterprises engaged in oil processing, transportation and distribution of oil products. Tank is filled with oil or oil products to maximum level. Concentration of hydrocarbons in the vapour-air mixture at the outlet of the neck of the tank is measured. Moment of the beginning of oil or oil product filling is recorded. Time interval from the beginning of filling to the initial appearance of hydrocarbons in the vapour-air mixture is recorded, which is taken as the minimum concentration value. Period of time until the maximum concentration of hydrocarbons in the vapour-air mixture is reached and the period of time until reaching the maximum filling level are recorded. Initial temperature of the outgoing vapour-air mixture of hydrocarbons is measured. At the end of filling up to the maximum value, the final temperature of the outgoing vapour-air mixture of hydrocarbons is measured. Sample of the vapor-air mixture of hydrocarbons is taken. Molar mass of hydrocarbons in the taken sample is determined and the mass of oil or oil products losses from evaporation in emissions of the vapour-air mixture during filling into transport tanks is determined by formula
where Mvl is mass of losses of oil or oil products from evaporation in emissions of vapour-air mixture, kg; Vts is the volume of the tank, which is the volume of the gas space of the tank, m3; tts is the time interval from the beginning of the tank filling to the maximum filling level, min; Cmax is the maximum weight concentration of hydrocarbons in the vapour-air mixture, kg/m3; Cmin is the minimum weight concentration of hydrocarbons in the vapour-air mixture, kg/m3; tCmax is the period of time from the beginning of filling to the release of vapours with concentration Cmax, min; tCmin is the period of time from the beginning of filling to the release of vapours with concentration Cmin, min; R is universal gas constant; Mvap is molar mass of vapours of hydrocarbons of oil or oil products, g/mol; Pa is atmospheric pressure, Pa; T1 is the temperature of the outgoing vapour-air mixture at the beginning of filling, K; T2 is the temperature of the outgoing vapour-air mixture at the end of filling, K.
EFFECT: higher accuracy of determination of losses of oil and oil products from evaporation of hydrocarbons at filling of transport tank due to determination of additional mass of losses formed due to evaporation of hydrocarbons and change of thermodynamic state of vapour-air mixture.
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