The article is devoted to the study of methods for modeling the operation of rectification columns using the HYSIS application software package. Such studies are very important not only for design, but also for the functioning of existing industries. The article proposes to use for combining nozzle devices in the concentration part of the column, and plate-shaped structures in the distant part of the column for more efficient and stable operation of distillation columns. To determine the hydrodynamic parameters of the operation of distillation column, a technique of determining the range of stable loads and the position of the operating point inside or outside the range of stable loads was taken. A column model was constructed using the HYSYS software package for separating gas mixtures with various contact devices: sieve trays, Rashig ring nozzles. Experiments for the same type and combined contact devices were carried out and their comparison was carried out in terms of hydraulic calculation and operating range. As a result of experiments with the use of the HYSYS software package, it was shown that the combined arrangement of contact devices can provide a stable hydraulic mode, in contrast to the use of similar contact devices.