EFFICIENCIES OF SIEVE TRAY DISTILLATION COLUMNS BY CFD SIMULATION

A 3-D two-fluid CFD model In the Eulerian framework was developed to predict the hydrodynamics, heat and mass transfer of sieve trays. Interaction between the two phases occurs via interphase momentum, heat and mass transfer. The tray geometries are based on the large rectangular tray of Dribika and Biddulph (AIChE. J., 32, 1864, 1986) and FRI commercial-scale sieve tray of Yanagi and Sakata (Ind. Eng. Chem. Process. Des. Dev., 21, 712, 1982). In this work a CFD simulation is developed to give the predictions of the fluid flow patterns, hydraulics and mass transfer efficiency of distillation sieve trays including downcomer. The main objective has been to find the extent to which CFD can be used as a design and prediction tool for real behavior, concentration and temperature distributions and efficiencies of industrial trays. . Despite the use of simple correlations for clasure models, the obtained efficiencies are very close to experimental data. The results was shown that values of point efficiency has been varied with position on the tray, because of variation of affecting parameters, such as velocities, temperature and concentration gradients and interfacial area. Downcomer region shows a region of high gas holdup in the vicinity of weir, and affects the tray hydrodynamics and mass transfer efficiency. Especially in the systems with a high volatile component evaporation of light component takes place in the downcomer, as that observed in binary systems contain methanol. The simulation results are shown that CFD can be used as a powerful tool in tray design and analysis, and can be considered as a new approach for efficiency calculations.

Keywords:

Computational Fluid Dynamics , Distillation Column , Sieve Tray , Hydrodynamics , Tray Efficiency , Mass Transfer