Studies on water carrying of diesel oil in upward inclined pipes with different inclination angle

•The case of accumulated water in upward inclined pipes was analysed.•A large flow loop was applied to analyse the flow characteristics.•A series of 50 mm acrylic bends with different inclination were used.•The experimental situation was simulated by using CFD techniques.

The characteristics of oil-water two phase flow in the case of water initially accumulated at low position in upward inclined pipelines were researched. A large scale experiment loop was conducted to analyse the flow characteristics by using a series of 50 mm transparent acrylic bends with different inclination angle (10° ∼ 45° at the interval of 5°). Five flow patterns were identified and a corresponding flow pattern map was established. The same situation was also simulated by using computational fluid dynamics (CFD) techniques, and the results of simulation were validated by comparing with the experimental results. The impact of oil superficial velocity, inclination angle and initial water volume on flow characteristics was further investigated. The results indicate that the backflow effect in water phase is the major factor that causes water accumulation at the bottom of the pipe. The initial residual water volume has no influence on the oil-water flow pattern and the water-carrying capacity of oil. The lower flow rate and the higher inclination angle cause the decrease of water-carrying capacity of oil, resulting in the water accumulation at the low position and internal corrosion of product oil pipelines.