Václav Kolář

On the hydrodynamics of sieve plates without downcomers.: I. Dynamic nature of the gas—liquid dispersions

Abstract The random fluctuations of the pressure drop across the gas—liquid dispersion have been recorded at a point near the centre on sieve plates without downcomers. A 300 mm; diameter single plate column was used. Different plate designs have been investigated using the system air—water. The statistical properties of the froth pressure drop time—histories were evaluated by a digital method. Operating regimes were defined in terms of the statistical properties evaluated. The relation between the standard deviation of the froth pressure drop fluctuations and the average liquid hold-up was established. The frequencies of the macroscopic periodic stationary waves (occuffing under certain conditions) have been studied as a function of the dispersion height and gas flow rate.

On the hydrodynamics of sieve plates without downcomers.: II. A model of plate operation and the phenomenon of multiplicity of steady state

Abstract A simplified statistical model of the plate operation in the homogeneous froth regime is presented. The model is based on the previously determined statistical properties of the pressure drop across the dispersion 1 . Equations are proposed which enable the evaluation of the equilibrium liquid hold-up in terms of the flow rates and plate geometry. The equations also predict the fractions of the free area associated with the gas flow, the liquid flow and the blocked area. The model contains a parameter which was experimentally determined and correlated. The phenomenon of occurrence of two steady states corresponding to two different equilibrium liquid hold-up values, for the same gas and liquid flow rates, was also investigated, and the regions of its occurrence determined. The corresponding states were shown to belong to different regimes and the occurrence of either state to depend on the path followed to reach the steady state.

A Model of the effect of the distribution of liquid on liquid hold-up in a packed bed and a new concept of static hold-up

Abstract An analysis is given of the effect of column diameter, packing size and bed depth on the hold-up through the parameters of the distribution of liquid i

The structure and height of the gaseous—liquid mixture on sieve plates without downcomers

Abstract A theoretical relationship derived earlier has been tested by measuring the variation of the pressure drop across the gas—liquid mixture on a sieve plate without downcomer. The single empirical parameter contained in the relationship describing the structure of the mixture has been correlated. The same relationship has also been successfully utilized to calculate the height of the gas—liquid mixture on the plate. A total of 14 plates without downcomers have been studied under various flow rates of gas and liquid.