An experimental study was conducted to investigate liquid entrainment in gas at high pressure. The liquid entrained refers to the fraction of the liquid phase suspended and transported in the gas phase in the form of droplets. Testing was conducted in a 2-inch horizontal pipe and a liquid film removal device was used to obtain the entrainment fraction. Two sets of tests were conducted: oil-N2 and water-N2 at pressures up to 1,000 psig, with superficial gas velocities between 2-m/s and 24-m/s, and superficial liquid velocities between 0.002-m/s and 0.1-m/s. Wave measurements were also performed during the nitrogen-water testing using conductance probes.
When two-phase gas-liquid mixtures flow in a pipeline, the distribution of the gas and the liquid phases within the pipe depends on the velocity, fraction of each phase, fluid properties, pipe geometry, and inclination angle. The arrangement of the gas and liquid phases into steady-state configurations are called flow patterns (1). In a wet gas stream which is dominated by the gas phase, two main flow patterns can be observed in horizontal pipes, Stratified flow (smooth or wavy) and Annular flow. The Stratified flow pattern is characterized by the bulk of the liquid running at the bottom of the pipe and gas flowing at the top of the pipe. As the gas velocity increases, waves form at the gas/liquid interface, this allows for droplets to detach from the liquid and travel with the gas. The entrainment fraction is a result of the atomization and deposition processes that take place in a gas/liquid system dominated by the gas phase. At sufficiently high gas velocities a fraction of the liquid is atomized and carried by the gas in the form of droplets while the rest flows as a film wetting the pipe walls resulting in Annular flow.