Simulation analysis of gas–liquid flow and mass transfer in a shaking triethylene glycol dewatering absorber

Abstract

Tall towers with large diameters on floating liquefied natural gas devices are highly sensitive to sway. If tower equipment is relatively high, swaying can easily cause uneven gas–liquid contact in the tower, inhibiting its absorption capacity. In this paper, gas–liquid counterflow triethylene glycol dehydration absorption towers are taken as the research object. A porous medium model was used to simplify the packing environment, and the Euler–Euler method was used to simulate the flow field in the tower. The flow field encompasses the effects of the gas–liquid phase dispersion force, gas–liquid phase diffusion coefficient, and interphase mass transfer. By introducing a dynamic grid model to establish sway boundary conditions, we quantitatively examine the influence of sway duration and angle on gas–liquid flow and mass transfer performance in absorption towers. The results show that, when the sloshing angle of the absorption tower is 9° and the sloshing period is 20 s, the influence of the disturbance of the absorption tower's internal flow field is increased by 85% and 78% respectively compared with normal working conditions. When the sloshing angle of the absorption tower is 9° and the sloshing period exceeds 21 s, the gas–liquid mass transfer inside the absorption tower diminishes. When the sloshing period of the regeneration tower is 6 s and the sloshing angle reaches 20°, the mass fraction of poor ethylene glycol in the regeneration tower fluctuates significantly in the first sloshing cycle, and unqualified products appear.

Keywords

• Sway
• Triethylene glycol dehydration
• Numerical simulation
• Gas-liquid flow
• Mass transfer performance