Multiphase Flow in Pipes
Authors: Griffith Peter 
Published: December 2007

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleum engineering.

Introduction
Multiphase flow is found in many places. In the petroleum industry it occursin oil and gas wells, petroleum industry it occurs in oil and gas wells, gathering systems, many piping systems, and key pieces of equipment needed inrefineries and pieces of equipment needed in refineries and petrochemical industries, including boilers, petrochemical industries, including boilers, condensers, distillation towers, separators, and associated piping. This article focuses on two-phase flow in pipes. Though a lot-has been learned about two-phase flow in the past 25 years, much of that knowledge has not been collected in a convenient place. In particular, much work done for the nuclea rplace. In particular, much work done for the nuclear industry remains unknownto the petroleum industry. The primary goal of this article is to describe the kinds of problems we are now able to solve and to point out where answers to these problems can be obtained. When piping in which two phases are flowing is designed, a number of questions can arise, depending on the application:What is the void fraction?What is the pressure drop?What is the liquid level?What is the flow at a break?How can one separate the phases?Where will corrosion occur?What is the wear rate caused by dropletim pingement?What is the vibration of the pipes as a result of two-phaseflow?
I shall begin by listing available books, then recommend flow-regime mapsand correlations for void, pressure drop, and critical flow, and finally touchon the problems of separation, corrosion, wear, and vibration.

Books on Two Phase Flow
Various books on two-phase flow contain answers for many of the problemsthat arise. Almost all of the following books describe homogeneous andseparated flow models for calculating void fraction and pressure drop, so Ishall mention only those features unique to each book. Wallis contains the mostcomplete mechanistic descriptions of void and pressure drop for the different flow regimes. Hestroni has a unique section on flow instability and also thebest section on flow regimes. Collier is primarily a multi phase heat-transferbook but has a unique section on two-phase pressure drop in fittings. Hewittand Hall-Taylor collect and report more experimental observations on annularflow than any other source. Lahey and Moody have a unique section on chokedflow. Their description of the drift-flux model is excellent. Govier and Azizconsider both slurries and non-Newtonian fluid plus a wide variety of solid, liquid, and gas systems. Moore and Sieverding have design data on screen andchevron separators that are not reported elsewhere. Hsu and Graham considercryogens. Szilas has a design section on both pool and cyclone separators.

Flow Regimes
The unique feature of two-phase flow is the presence of flowregimes-descriptions of how the two phases are distributed in the pipe.
JPT
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