Experimental Study on Three Phase Flow in Inclined Pipe for Deep Sea Mining

Subsea minerals exist in the deep water within Japanese exclusive economic zone. However, the development of subsea minerals is not commercialized. The Air-lift pump is the promising method for subsea minerals transport. It is significant to estimate the amount of lifting ore when the conditions of submergence ratio and supplying air volume are changed. The estimation of the amount of lifting ore needs the void fraction in three phase flow and friction loss in pipe. Therefore, the empirical methods to estimate the void fraction and friction loss in mainly vertical pipe were proposed in the previous studies. However, the lifting system for subsea minerals has not only vertical pipe but inclined pipe. There are few works for flow assurance on three phase flow in inclined pipe. Then we conducted the scale model experiment to investigate void fraction and friction loss. The experiment was conducted in the conditions of the five kinds of inclination angles. We used the glass beads as solid particles in the experiment. The glass beads were 4mm in diameter and 2553kg/m3 in density. The internal diameter of pipe was 26mm. We applied the empirical method for vertical or horizontal pipe proposed in previous researches to the present experimental condition. Then we compared the experimental results with the calculated ones on void fraction and friction loss. As the results, the calculated results were in good agreement with the experimental ones. Therefore, it was suggested that the void fraction and friction loss in the inclined pipe could be calculated by the empirical method based on the experiment on the vertical or horizontal pipe.