CFD Characterization of Liquid Carryover in Gas/Liquid Separator With Droplet Coalescence due to Vessel Internals

摘要

Liquid carryover in gas/liquid separators has been numerically characterized by using the Euler-Lagrange multiphase formulation together with correlations specifically developed to account for droplets coalescence due to the vessel internals. With this approach, contribution of vessel internals to flow distribution is addressed with porous medium treatment, and contribution to separation performance is considered using the local changes of equivalent mean-droplet size across each vessel internal. Numerical verifications on two vessel configurations operated at high and low pressures have shown that the vessel with proposed internals outperform the vessel with original internals, hence minimized liquid carryover rate is achieved. This CFD prediction agrees well with the existing separation theory and practical observation since only a partial perforated baffle and a vane pack are available in the original vessel. The proposed vessel however integrates the perforated baffles as flow distributor, mesh pad as droplet coalescer, and spiral flow cyclone as mist demister. Of course, combination of these vessel internals makes the proposed vessel a great upgrade to the original vessel. It is therefore demonstrated that not only CFD can be applied to characterize the overall flow distribution, but also can be extended to quantify liquid carryover, hence the separation performance of gas/liquid separators, no matter they are operated in onshore, offshore, or subsea upstream processing industries.