Hydraulics of Sieve Trays with Gas Mal-Distribution

Hydraulics of Sieve Trays with Gas Mal-Distribution

A transient three-dimensional two-fluid computational fluid dynamics (CFD) model is developed in the Eulerian framework to predict the hydraulics of sieve trays, especially with gas maldistribution. For this purpose, an algorithm is developed to explain the hole-gas velocity and pressure drop terms along the liquid flow path length. An important modification to the previous CFD works is the use of variable, position dependent, gas superficial velocity for calculation of interphase drag term along the tray. The flow path length of tray was divided into a number of sections; gas-superficial velocity, hydraulic parameters and drag coefficient were obtained for each section. This modification has an important effect on the simulation results, causes faster convergence and better predictions of tray hydraulics. The results are in good agreement with experimental data. Model results obtained in this study have revealed that the effect of hydraulic gradient is significant for high liquid path length and may create non-uniform gas flow. The best way to determine liquid head pressure loss and thus clearing the pressure drop prediction problem is to use CFD simulations. This paper is described how the inlet flow maldistributions can be included in CFD simulation of sieve trays. It is aimed to be a starting point for using CFD techniques in design-oriented and parameter estimation simulations of trays, and yields useful data, without doing expensive experimental works.