Experimental Investigations of Droplet Deposition and Coalescence in Curved Pipes

Abstract

Even though there have been several studies conducted by the industry on the use of different inlet devices for gas-liquid separation, there have been limited laboratory and field evaluations on the use of external piping configurations as flow conditioning devices upstream of a separator inlet. The results of a systematic study of droplet deposition and coalescence in curved pipe and pipe fittings are reported in this paper. A facility has been designed consisting of two main test sections: a fixed horizontal straight pipe section and an interchangeable 180 deg return pipe section (or curved pipe section) of the same length. Both inlet and outlet to the 180deg return are horizontal, but the plane of the 180 deg return pipe section can pivot about the axis of the inlet horizontal pipe to an angle as much as 10 deg downwards allowing downward flow in the return section. Various pipe fittings of different radius of curvature can be installed for comparison in the 180 deg return. Eittings evaluated in this study included: 180 deg pipe bend, short elbow bend (with standard radius of curvature of 1.5D), long elbow bend (with custom radius of curvature of 6D), target tee bend, and cushion tee bend. Experiments have been carried out using water and air, and varying gas velocities and liquid loadings. In order to compare the peiformance of geometries. Droplet Deposition Eractions (DDE) were measured in the horizontal straight pipe section and in the 180 deg return pipe section as a measure of coalescence efficiency. The results demonstrate that higher DDE occurs for curved fittings as compared to the straight pipe section. The short elbow bend has approximately 10% DDE higher, whereas long elbow bend along with 180 deg pipe bend peiform better (by 15-20% DDE) than straight pipe. It was found that the cushion tee and target tee bends can coalesce droplets at lower gas velocities but break up droplets at higher gas velocities. Additionally, no significant differences between DDE's in three different inclination angles of a curved pipe were observed. It can be concluded that 180 deg pipe bend or two 6D long radius elbow bend can serve as a droplet coalescer; a pair of cushion tees or target tees can also work as coalescers at low kinetic energy but as atomizers at high kinetic energy.

Numerical Investigation of an Efficient Method (T-Junction With Valve) for Producing Unequal-Sized Droplets in Micro- and Nano-Fluidic Systems

“…Also, these systems have many other advantages such as better mixing of the reactants that are inside the droplets due to the circulation of the flow inside the droplets [2]. In these systems, processes, such as the formation [3][4][5][6], deformation [7], breakup in symmetric [8] and asymmetric [9,10] geometries, coalescence [11], mixing, and transport [12] of droplets, occur. Therefore, many investigations have been conducted to study these processes over the last decade [10][11][12][13][14][15][16][17].…”

Solid-Particles Flow Regimes in Air/Water Stratified Flow in a Horizontal Pipeline

“…A unique facility was designed and constructed with a horizontal 4-in. transparent polyvinyl chloride (PVC) pipe, which measures liquid velocity, liquid holdup, and pressure drop (Nguyen et al 2014). The designed test loop uses water as its liquid phase and air as its gas phase, along with glass beads with spherical shape representing the solid particles.…”