Improved Static Mixer Design for Achieving Equal Phase Splitting at Pipe Junctions

Abstract

Abstract In many operations such as steam injection, production line splitting and simultaneous water and gas injection, it is desirable to split a stream of multiphase flow into two or more substreams. In these types of operations it is essential that all the sub-streams have the same gas/liquid ratio as the main stream. A significant problem in multiphase flow splitting is the phase separation which occurs at branches in a piping network. The higher density phase, because of its greater momentum, will tend to flow in the straight or least deviated pipe branch, while the lower density phase will tend to flow into the most deviated branch of pipe. The conventional practice for multiphase flow splitting is to mix the phases before the pipe junction. This is usually achieved using static mixers of the helix type. These mixers consist of an axial sequence of static propellers of the same diameter of the pipe in which they are located. The energy required to mix is provided by the moving fluid. Adequate mixing is often difficult to achieve in large diameter pipes with low mixture velocity. An improved static mixer using packed bed technology was developed and tested in the laboratory with air and water. Laboratory results indicate this improved mixer can achieve equal phase splitting in 6" pipe with mixture velocities which are an order of magnitude lower than those required by helix type mixers.