Large diameter pipes experience significantly different flow patterns in comparison to small diameter pipes. Previous studies
have shown that the ability to reproduce flow patterns similar to those in large diameter pipelines diminishes greatly for pipelines with an
internal diameter less than 10 cm. All multiphase flow studies at the Institute are carried out in 4-inch or 10 cm I.D. pipelines for direct
correlation to larger scale systems.
Erosion Corrosion in Multiphase Flow
Material degradation in industrial pipelines occurs through two main processes: corrosion and erosion. Corrosion is a chemical
or electrochemical degradation process by which electrons from the target metal are lost to corrosive species in the process fluid and the
remaining metal cation is left to be dissolved into the fluid or to form a protective film. Erosion occurs due to the impact of particles on the
surface of pipe walls which mechanically removes material from the target metal surface. Industrial pipelines which transport corrosive species and
solid particles are subject to erosion-corrosion. If both erosion and corrosion occur at the same time there is a chance that a synergistic effect
may cause the amount of metal loss to be greater than the sum of metal loss due to erosion and corrosion. For highly used industrial materials
such as carbon steel it is important to know how the material will wear in erosion-corrosion environments. Despite the extensive studies performed
on pure corrosion and pure erosion mechanisms there have been few studies in order to determine the mechanisms that occur during erosion-corrosion
processes. Text written by Josh Addis.
Multiphase Flow in Hilly Terrain
A unique, 10-cm diameter, 18-m long pipeline has been constructed to simulate localized multiphase oil/water/gas flow and
corrosion in the vicinity of road and river crossings and in hilly terrain topography with short, abrupt inclination changes. The multiphase flow
line involves flow over a horizontal distance of 6 m before reaching the crossing section. Four 9D (nine-diameter radius) bends with 2-m pipelines
for the riser, crossing, and downcomer sections make up the crossing section. The multiphase mixture then flows through a 4-m horizontal discharge
section into a separation tank. This highly complex system exhibits flow regimes from horizontal, inclined, and vertical flows. At any given gas
and liquid flow rate, this system can experience 9 different flow regimes in different regions at the same time. The corresponding corrosion
mechanisms and corrosion rates will vary dramatically.
Inclined Multiphase Flows
Unlike single-phase flows, multiphase flows are strongly influenced by the geometry of flow. Of the many variations in pipe
geometry, the strongest influence is from the pipe inclination. Even an inclination of 0.5 degrees can dramatically alter the flow patterns, the
boundary layer structure, and the fundamental transport mechanisms. Two separate pipelines, 30 m in length, are located atop a 16,000 lb structure
that is fully inclinable from horizontal to vertical. The transparent pipe sections allow for flow visualization when studying the effect of
inclination on flow patterns in multiphase flows containing sand, oil, water, gas, and/or drag reducing agents (DRAs).