Experimental investigation for liquid holdup reduction of subsea riser with surfactant

摘要

The principal pressure drop in a subsea riser is generally the gravitational pressure drop component due to liquid holdup. Surfactant is a kind of Chemical compound related to flow improvement. Gasliquid two-phase flow in subsea riser with zero and small liquid flow rates was simulated in two vertical tubes with diameters of 40mm and 65mm, respectively. Liquid holdup reduction of subsea riser was investigated with surfactant. The simulation was conducted at low pressure, using air as the gas phase and water as the liquid phase. Pressure drop was measured by using differential pressure transducer and holdup was obtained by trapping the liquid in the pipe section. Different trace amounts of surfactant were used in this vertical two-phase flow system. The liquid holdups were measured at different surfactant concentrations and different gas-liquid flow ratios. Liquid holdups with and without surfactant additives are compared and analyzed. How the foamer influences the two-phase flow pattern was observed and the range of foamer concentration corresponding to the best holdup reduction was obtained.