(26d) Demystifying the Zero Entrainment Myth

In the last few years the importance and feasibility of vacuum tower inlet devices having very little or no entrainment to the column slop draw has been very strongly promoted. Entrainment from the flash zone is only one aspect which determines the quality and yield of vacuum gas oil which can be obtained for given crudes.

In the presentation all aspects influencing the vacuum gas oil quality are considered. Starting from the flash we will look at entrainment from the inlet device, de-entrainment characteristics of the internals in the wash section and entrainment from the wash oil distributor.

For each of these aspects experimental data, CFD analysis and data obtained from actual columns will be shown. Results from modeling of different radial and tangential inlet devices as well as a modeling of entrainment from spray nozzle distributors will be presented.

Finally the importance of all of these factors determining the maximum yield for a given quality of vacuum gas oil in particular the effect of entrainment of the inlet device are put in perspective.