A "Two region" model is proposed. By consider the discrimination of "re-gimes"

drop size distribution

projection velocities of drops and variations of drag coefficients

an integration model is derived. It can reasonably explain the variations of limiting gas velocities with many facts

such as plate spacing

gas density

and liquid flow rate etc. After simulations and further simplifications

two simple equations are obtained. From tests with the data of various industrial plates and practical engineering design methods

the results are satisfactory

and the parameters obtained from fitting in with the data of industrial plates are in good agreement with those in the laboratory correlations from the literature.