Анализ методик измерения равновесных условий образования газовых гидратов

Abstract

In this work, we analyze the factors that affect the experimental determination of the gas hydrate equilibrium conditions in various systems using step heating and ramp heating by GHA350 stirred autoclave or RCS6 rocking cells. It has been found that more reliable results are obtained using the GHA350 autoclave, which provides a more intensive mixing of the fluids. Step heatingis a priori a more reliable way to determine the equilibrium conditions of hydrate formation, suitable for any system. However, its application is time-consuming. An alternative heating method at a constant rate of 0.1-1 deg./h can significantly reducethe time of one measurement. However, when using it, to obtain reliable experimental data, it is necessary to select the heating rate considering the mixing efficiency of the setup used, the type of system under study, and other factors. For most systems, the results of measuring the hydrate equilibrium temperatures by step and continuous heating at 0.1 deg./h using GHA350 autoclaveare consistent within the measurement error. A greater discrepancy between the methods is observed for gas hydrates in concentrated salt solutions, which have a high viscosity at low temperatures.