Equal Quality Distribution of Two-Phase Fluid by Isokinetic Principle

Abstract

In thermal recovery of heavy oil, phase separation often occurs when a steam-water stream turns to branches in a junction and distributor, thereby resulting in a significant quality deviation between branches. Although a lot of efforts have been made during the past decades, the problem is still not well solved. Inspired by the principle of the isokinetic probe, this paper builds a new model of distribution. The major change is that the inner space of the main pipe is isolated into fan-shaped isokinetic flow channels, each connecting to a side branch. Flow control devices are installed at the outlet of each branch. Moreover, a swirler is used to convert the incoming flow pattern into a uniform swirling gas core-annular flow before the new isokinetic dividing system. Computational fluid dynamics (CFD) simulations were conducted to reveal the characteristics of gas-liquid two-phase flow within the distributor. The characteristics of both under isokinetic and nonisokinetic flow conditions were analyzed. The most interesting result is that once the uniform swirling gas core-annular flow is formed, liquid film flow becomes very stable and is almost unaffected by the operation deviations from the isokinetic condition, whereas gas flow is much more sensitive to the deviations. The more deviation of isokinetic condition, the more deflection of gas flow or phase separation will take place and the greater quality deviation will be. Air-water two-phase flow experiments were also conducted to verify the CFD results.