METHOD FOR DETERMINING THE CRITICAL PARAMETERS OF FLUIDS Russian patent published in 2022 - IPC G01N25/02 

FIELD: measuring.

SUBSTANCE: invention relates to the field of experimental determination of the critical parameters of binary and multicomponent fluids, and can be used in the petroleum and gas industry and the chemical industry, as well as in scientific departments studying the problems of modelling the phase behaviour of multicomponent fluids. Method for determining the critical parameters of a fluid includes instrumental determination of the critical parameters of fluids based on two main universal indicators of the liquid/gas critical point, namely, based on the absolute maximum of critical opalescence being reached on the side of the single-phase state region and based on the meniscus appearing at the liquid-gas interface in the middle of the inner volume of the optical cell at the transition to the two-phase state region. Optical measurements are taken in a horizontal scattering plane dividing the inner volume of the optical cell in half. Transition of the fluid from the single-phase to the two-phase state over the boundary curve is marked by sharp lambda-shaped peaks in the measured light-scattering intensity. Passage of the meniscus through the scattering plane, i.e., through the middle of the inner volume of the optical cell, is marked by narrow local minima in the measured light-scattering intensity. The critical point is determined by graphical plotting as the intersection point of the line of points of passage of the meniscus through the middle of the inner volume of the optical cell with the experimentally determined boundary curve, and the values of density, temperature, and pressure at this point are taken as the critical parameters of the fluid.

EFFECT: higher reliability and accuracy of determining the critical parameters of a fluid.

1 cl, 10 dwg, 1 tbl