Study of mist flow inside a vane pack geometry

Abstract

Vane pack demisters in the industry operate with natural gas at pressures up to 100 bara. A new vane pack has been compared with the traditional one used by the industry. The vane packs have been investigated through experiments and Computational Fluid Dynamics, CFD. The fluid flow inside a vane pack consist of turbulence and two fluid phases. The simulations were carried out with a Large Eddy Simulation model and a Scale-Adaptive Simulation model. Phenomena observed in the experiments were confirmed by CFD. A transient Discrete Phase Model,DPM, that should be capable of modeling the generation of a liquid film together with droplets was used. The DPM simulation gave a mist flow pattern that agreed with the one observed in the laboratory. Separation efficiency measurements of the two vane packs using Exxsol D60 as liquid and SF6 as gas were performed at different pressures, ranging from 1 to 8 barg. This corresponds to natural gas density ranging from 8 to 65 barg. Non of the experiments achieved the specification given by the oil and gas industry. The efficiency measurements did show that the pressure had a great influence on the performance. The low pressure measurements were the only experiments which had a efficiency above 97% at a k-value between 0.2 - 0.25 m/s.