Numerical simulation of two-phase flow and mass transfer performance in offshore FLNG gas-liquid counter-current whole column

Key words:  countercurrent column  FLNG  sloshing condition  numerical simulation  flow and mass transfer

Abstract:

FLNG is a floating production equipment which integrates the functions of offshore natural gas production, processing, liquefaction, storage and handling.Sour gas removal is a key step in the process of natural gas liquefaction. The gas-liquid countercurrent packed tower installed on FLNG is the general research object, and the porous medium model is used to modeling the structured packing. Considering the effects of porous medium resistance, interphase drag force, dispersion force and gas-liquid phase, and introducing dynamic meshes, a numerical model of packing tower under sea conditions is established, where the impacts of the inclining angle, sloshing angle and vibrational period on the gas and liquid flow field and the mass transfer performance in the packing tower are quantitatively studied.The results indicate that the inclining condition with aninclining angle greater than or equal to 3 degrees can significantly affect the liquid distribution in the column, and the uniformity index of liquid distribution decreases by 30％ around,compared with that in the non-inclining condition. When the sloshing period is 6 s and the value of the inclining angle ranges from 1 to 6 degrees, the non-uniformity can be improved to some extent. The fluctuation range of the mole fraction of CO₂ in the purified gas increases by 87％ when the sloshing period is 10 s.