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Horizontal Two-Phase Flow Calculation


Two-phase horizontal flow regimes are based on the Baker Chart for vapor-liquid non-flashing flow through circular ducts (pipe). It is further assumed that the line pressure drop is less than 10% of the absolute pressure to support the use of a single vapor density and flow regime for the entire line. Violation of this assumption requires the line to be broken into a number of segments which individually have pressure drops less than 10% of the segment absolute pressure.


Each flow regime has an individual pressure drop correlation. The pressure drops for stratified, plug, slug, and annular flow regimes are based on correlations by Baker. The wave flow regime pressure drop is based on the Huntington correlation. The dispersed flow regime is based on the Lockhart-Martinelli correlation for turbulent flow in both phases.


Mandhane, Gregory and Aziz present a brief discussion of the difficulties of discontinuities arising from composite pressure drop methods as used here and in their paper. A brief quotation from that work will suffice to highlight the difficulties.

"A serious potential problem associated with the use of any composite design procedure is related to discontinuities that may occur at flow-regime transition boundaries. These arise from using different methods of correlations in adjacent increments of the pipeline where flow conditions are only marginally different."


References:

General Discussion

  • Robert Kern, "How to Size Process Piping For Two-Phase Flow," Hydrocarbon Processing (October 1969) p. 105-116.
  • J.M. Mandhane, Gregory, G.A., Aziz, K., "Critical Evaluation of Friction Pressure-Drop Prediction Methods for Gas-Liquid Flow in Horizontal Pipes," Journal of Petroleum Technology (October 1977) p. 1348-1358.

    Flow Regimes and Pressure Drop

  • Ovid Baker, "Design of Pipelines for the Simultaneous Flow of Oil and Gas," Oil and Gas Journal (July 26 1954) p. 185-195.
  • A.K. Coker, "Understanding Two-Phase Flow in Process Piping," Chemical Engineering Progress (November 1990) p. 60-65.
  • R.W. Lockhart, Martinelli, R.C., "Proposed Correlation of Data for Isothermal Two-Phase, Two-Component Flow in Pipes," Chemical Engineering Progress (January 1949) p. 39-48.



    Horizontal Two-Phase Flow Calculation
    Copyrighted 2000, 2003
    Last updated 04May03