Two-Phase Flow Induced Vibrations With CO₂ Multiphase Flow

In CO2 storage plants, internal multiphase flow of CO₂ may occur in piping elements in various parts of the process. From the energy and process industries, it is known that multiphase flow can induce high amplitude vibrations, especially in flexible piping. In the last decade, experimental data sets and results from excitation spectrum modelling have become available for fluid systems involving oil, gas, water, and steam. Multiphase flow-induced vibrations are affected by fluid properties, and the properties of CO₂ are quite different from those of water and oil. To address this uncertainty a multiphase CO₂ test campaign was performed in the same flow loop that high pressure gas/water/oil experiments had been performed previously. The vibrations measured in the CO₂ tests were in line with those measured in the high pressure gas/water and gas/oil cases. Although multiphase flow of CO₂ tends to be more mixed and with less slip than typical of the other fluid systems, the measured vibrations are still a factor of 2–3 higher than for single-phase liquid CO₂ flows. A conclusion is that CO₂ multiphase induced forces can be modelled in line with the high pressure gas/water systems.