Page 142 - Chemical Process Equipment - Selection and Design

114 FLOW OF FLUIDS

Bubble Slug

. .
. .
. ..
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Plug Annular . ,.
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..
. .
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Stratified Dispersed . ..
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Wavy Bubbly Annular Dispersed
(a)

lo - Dispersed flow IDB)

J
vi 3
3z
d

Stratified
flow LSS)
-
.01

.1 1 10 100 500
UG mls

Figure 6.7. Flow patterns and correlations of flow regimes of liquid-gas mixtures in pipelines. (a) Patterns in horizontal liquid-gas flow. (b)
Patterns in vertical liquid-gas flow. (c) Correlations of ranges of flow patterns according to Baker [Oil Gas J. 53(12), 185 (1954)], as
replotted by Bell et al. [Chem. Eng. Prog. Symp. Ser. 66, 159 (1969)l; u is surface tension of the liquid, and ow that of water. (d) Flow
regimes of water/air at 25°C and 1 atm [Tuitel and Dukler, AIChE J. 22, 47 (1976)l; the fuzzy boundaries are due to Mandhane et al. [Int. J.
Two-Phase Flow 1, 537 (1974)l.

SEPARATED FLOW MODELS 1000 instead of the usual 2000 or so because the phases are
recognized to disturb each other. Item 1 of Table 6.8 is a guide to
Pressure drop in two-phase flow is found in terms of pressure drops the applicability of the Lockhart-Martinelli method, which is the
of the individual phases with empirical multipliers. The basic
relation is oldest, and two more recent methods. An indication of the
attention that has been devoted to experimentation with two phase
flow is the fact that Friedel (1979) based his correlation on some
25,000 data points.
Example 6.14 compares the homogeneous and Lockhart-
Martinelli models for the flow of a mixture of oil and hydrogen.
The last term is the pressure drop calculated on the assumption that
the total mass flow has the properties of the liquid phase.
Some correlations of multipliers are listed in Table 6.8.
Lockhart and Martinelli distinguish between the various combina- OTHERASPECTS
tions of turbulent and laminar (viscous) flows of the individual The pattern of annular flow tends to form at higher gas velocities;
phases; in this work the transition Reynolds number is taken as the substantial amount of work done on this topic is reviewed by