CFD simulation of film flow and gas/liquid counter-current flow on structured packing

Abstract

A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area.

Keywords

two-dimension / computational fluid dynamics(CFD) / film distribution / countercurrent flow

References

[1] Zhao L. Q. Liquid Film Flows over Complex Surfaces [D]. 1991, Tulsa, Oklahoma, USA: Chemical Engineering Department, The University of Tulsa.

[2] Valluri P., Matar O. K., Hewitt G. F., et al. Thin film flow over structured packings at moderate Reynolds numbers [J]. Chem Eng Sci, 2005, 60(7): 1965-1975.

[3] Chang H. C. Wave evolution on a falling film [J]. Annu Rev Fluid Mech, 1994, 26(1): 103-136.

[4] Fulford G D. The flow of liquids in thin films [G]. Drew T B. Advances in Chemical Engineering, 1964. 151–236.

[5] Oron A., Davis S. H., Bankoff S. G. Long-scale evolution of thin liquid films [J]. Rev Mod Phys, 1997, 69(3): 931-980.

[6] Wang C. Y. Liquid film flowing slowly down a wavy incline [J]. AIChE J, 1981, 27(2): 207-212.

[7] Zhao L., Cerro R. L. Experimental characterization of viscous flows over complex surfaces [J]. Int J Multiphase Flow, 1992, 18(4): 495-516.

[8] Fernandesa J., Lisboaa P. F., Simõesa P. C., et al. Application of CFD in the study of supercritical fluid extraction with structured packing: Wet pressure drop calculations [J]. J Supercrit Fluids, 2009, 50(1): 61-68.

[9] Raynal L., Boyer C., Ballaguet J. P. Liquid holdup and pressure drop determination in structured packing with CFD simulations [J]. Can J Chem Eng, 2004, 82(5): 871-879.

[10] Raynal L., Royon-Lebeaud A. A multi-scale approach for CFD calculations of gas-liquid flow within large size column equipped with structured packing [J]. Chem Eng Sci, 2007, 62(24): 7196-7204.

[11] Szulczewska B., Zbicinski I., Górak A. Liquid flow on structured packing: CFD simulation and experimental study [J]. Chem Eng Technol, 2003, 26(5): 580-584.

[12] Hirt C. W., Nichols B. D. Volume of fluid (VOF) method for the dynamics of free boundaries [J]. J Comput Phys, 1981, 39(1): 201-225.