Effect of liquid properties on filtration performance of filters for lubricating oil separation from natural gas

Abstract

Lubricating oil droplets entrained in the gas seriously affect the gas injection capacity in porous natural gas storage. Liquid properties vary significantly under high pressure condition, which greatly change the filtration performance. In this paper, the effects of liquid viscosity, liquid surface tension and oil concentration on the filtration performance of industrial filters with different efficiency grades were investigated. As the upstream oil concentration is 4000 mg·m⁻³, for the same liquid surface tension, the filtration efficiency of the same filter increases with the increase of liquid viscosity; for the same liquid viscosity, the filtration efficiency first increases and then decreases with the increase of liquid surface tension in the range of 20.53–34.30 mN·m⁻¹, where the best filtration performance is found at 28.46 mN·m⁻¹. As the upstream oil concentrations increases from 4000 mg·m⁻³ to 6000 mg·m⁻³, the filtration efficiency increases for the liquid viscosity of 89.36 mm²·s⁻¹ and 234.30 mm²·s⁻¹, however, the efficiency reduces for 874.95 mm²·s⁻¹. An empirical prediction model for global saturation of filters was developed. The modelled results are in good agreement with the experimental results. Furthermore, it was found that there was a nonlinear relationship between the filtration efficiency and global saturation in the range of 0.10–0.53.