The experience of operating gas separation process units shows that it is not always possible to achieve effective separation of liquid particles. Traditional calculation formulas for determining the settling rate of particles in separators are based on the thermodynamic equilibrium of the main parameters of the incoming gas flow (pressure, density). At the same time, well production, in particular condensing gases, is a nonequilibrium system, which is characterized by a certain delay (relaxation times) in changing parameters. As a result of this delay, the settling rate of particles in the separator does not have time to reach the steady state Stokes regime corresponding to effective separation. The paper proposes a nonequilibrium model for the sedimentation rate of particles and developed an algorithm for its numerical implementation. Using this algorithm, multivariate computational experiments were carried out to study the dynamics of particle settling. It was found that for the effective separation of liquid particles in a gravity separator, the relaxation time for the settling velocity of the particles should not exceed 10 sec. Keywords: gas separation; gravity separator; particle settling rate; relaxation time.