Experimental study of flow pattern classification and severe slugging control in a pipeline-riser system

According to the characteristics of normalized pressure drop along the riser and the riser outlet liquid holdup, flow patterns that occurred within a pipeline-riser system was discriminated and classified into five categories-SS1, SS2, SS3, OSC and STB. Manual control, PID control based on riser base pressure and PID control based on riser pressure drop were carried out to eliminate the observed SSI in order to stabilized the periodic pressure and flow rates oscillations. The average values of riser bottom pressure, riser pressure drop and inlet liquid flow rates as well as the valve opening after severe slugging being stabilized by above-mentioned three control methods were compared to evaluate the control effects. The results show that the PID control strategy based on riser pressure drop presents the best performance with the largest valve opening and a relative high inlet flow rate, the PID control strategy based on riser base pressure takes the second place and the manual control shows the worst.