Vertical pipe flow patterns

The flow patterns typically encountered in vertical pipe flow are illustrated in Figure 23. The types of flow patterns encountered are as follows ... 

Figure 23. Flow patterns in vertical pipe flow.

The flow of a gas-liquid mixture in a pipeline is common. The flow patterns present should be recognized. For vertical piping, the pattern alone often determines the proper line size. Two-phase pressure drop correlations have a high uncertainty associated with them. Typically, the estimated pressure drop can be 40% of the true value. 

Liquids and Gases For cocurreut flow of liquids and gases in vertical (upflow), horizontal, and inclined pipes, a veiy large literature of experimental and theoretical work has been published, with less work on countercurrent and cocurreut vertical downflow. Much of the effort has been devoted to predicting flow patterns, pressure drop, and volume fractious of the phases, with emphasis on hilly developed flow. In practice, many two-phase flows in process plants are not fully developed. 

For fully developed incompressible cocurrent upflow of gases and liquids in vertical pipes, a variety of flow pattern terminologies and descriptions have appeared in the hterature some of these have been summarized and compared by Govier, Radford, and Dunn Can. J. Chem. Eng., 35, 58-70 [1957]). One reasonable classification of patterns is illustrated in Fig. 6-28. 

FIG. 6-26 Flow-pattern regions in cociirrent liqiiid/gas flow in upflow through vertical pipes. To convert ft/s to m/s, multiply by 0.3048. (Ftom Govier, Radfot d, and Dunn, Can. J. Chem. Eng., 35, 58—70 [1957].)... 

Rhodes, and Scott Can. j. Chem. Eng., 47,445 53 [1969]) and Aka-gawa, Sakaguchi, and Ueda Bull JSME, 14, 564-571 [1971]). Correlations for flow patterns in downflow in vertical pipe are given by Oshinowo and Charles Can. ]. Chem. Eng., 52, 25-35 [1974]) and Barnea, Shoham, and Taitel Chem. Eng. Sci, 37, 741-744 [1982]). Use of drift flux theoiy for void fraction modeling in downflow is presented by Clark anci Flemmer Chem. Eng. Set., 39, 170-173 [1984]). Downward inclined two-phase flow data and modeling are given by Barnea, Shoham, and Taitel Chem. Eng. Set., 37, 735-740 [1982]). Data for downflow in helically coiled tubes are presented by Casper Chem. Ins. Tech., 42, 349-354 [1970]). 

In vertical flow, axial symmetry exists and flow patterns tend to be somewhat more stable. However, with slug flow in particular, oscillations in the flow can occur as a result of sudden changes in pressure as liquid slugs are discharged from the end of the pipe. 

The principal flow patterns are shown in Figure 5.1. In general, the flow pattern map (Figure 5.2) is also applicable to vertical flow. Further reference to flow of gas- liquid mixtures in vertical pipes is made in Section 8.4.1 with reference to the operation of the air-lift pump. 

Barnea D, Luniski Y, Taitel Y (1983) Flow pattern in horizontal and vertical two phase flow in small diameter pipes. Can J Chem Eng 61 617-620 Baroczy CJ (1963) Correlation of liquid fraction in two-phase flow with application to liquid metals, NAA-SR-8171. Butterworth, London... 

Figures 3.1a and 3.16 show the flow patterns in vertical and horizontal pipes, respectively. Obviously, stratified flow does not exist in vertical flow, because of the relative direction of the flow and gravitational force, and a more symmetrical flow pattern is possible in vertical flow than in horizontal flow. Flow patterns identified in the figure can be described as follows.

Barnea, D., Y. Luninski, and Y. Taitel, 1983, Flow Pattern in Horizontal and Vertical Two-Phase Flow in Small Diameter Pipes, Can. J. Chem. Eng. 67 617-620. (3)... 

Akagawa, Sakaguchi, and Ueda (Bull JSME, 14, 564-571 [1971]). Correlations for flow patterns in downflow in vertical pipe are given by Oshinowo and Charles (Can. J. Chem. Eng., 52,25-35 [1974]) and Barnea, Shoham, and Taitel (Chem. Eng. Sci., 37, 741—744 [1982]). Use of drift flux theory for void fraction modeling in downflow is... 

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