Investigation of open hole area effects on the air dynamic pressure, Froude number, and hydraulics of distillation trays using CFD

Despite the significant effect of open hole area (OHA) on the distillation tray performance, no numerical study exists to investigate this parameter effect profoundly until now. In the present study, OHA effects on the hydraulics, air dynamic pressure, and Froude (Fr) number have been numerically investigated in commercial-scale sieve trays. To do so, three sieve trays with OHAs of 5, 8, and 14 percent have been studied. In the first step, simulations have been carried out to find the OHAdependent drag coefficient, and then, validation has been performed using published experimental data and correlations. Simulation results showed that, when the OHA increases from 5 to 14%, the average froth density, clear liquid height, and wet pressure drop increase by 20, 10, and 15%, respectively, while the average froth height reduces by 10% in different gas and liquid flow rates. The efficiency and entrainment values of three tray types have been qualitatively compared using Fr number and air dynamic pressure values, respectively, predicting the smallest value in the tray with 14% OHA. This study's results show that with pure hydrodynamic analysis, it is qualitatively possible to study the geometrical change effects on entrainment and efficiency with air dynamic pressure and Fr number, respectively.

Automated summary

This study numerically investigates the effect of open hole area (OHA) on the performance of distillation trays. The results show that increasing OHA leads to an increase in froth density, clear liquid height, and wet pressure drop, while reducing froth height. The efficiency and entrainment values of different trays with varying OHAs are compared using Fr number and air dynamic pressure, and the tray with 14% OHA is found to have the lowest values. Pure hydrodynamic analysis can be used to qualitatively study the effects of geometric changes on entrainment and efficiency.