Page 141 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Fluid Flow 125

Type of Flow For Horizontal Pipes Total System Pressure Drop

Bubble or Froth: Bubbles dispersed in liquid The pressure drop for a system of horizontal and verti-
Stratified: Liquid and gas flow in stratified layers cal (or inclined) pipe is the sum of the horizontal pres-
Wave: Gas flows in top of pipe section, liquid sure drop plus the additional drop attributed to each ver-
in waves in lower section tical rise, regardless of initial and final elevations of the
Slug: Slugs of gas bubbles flowing through line [33].
the liquid
Annular: Liquid flows in continuous annular L'i.PTPh = L'i.Ppy (horizontal pipe) + nhf', PL/144 (2-110)
ring on pipe wall, gas flows through
center of pipe A. To determine most probable type of two-phase flow
Plug: Plugs of liquid flow followed by plugs using Figure 2-40.
of gas
Dispersed: Gas and liquid dispersed
1. Calculate Wm A.\jl/G
2. Calculate G/t..
3. Read intersection of ordinate and abscissa to identi-
Segregated
fy probable type of flow. Since this is not an exact,
clear-cut position, it is recommended that the adja-
cent flow types be recorded also. Note: See Example
2-16 for definitions of A. and 'I'·
Stlatllled
B. Calculate the separate liquid and gas flow pressure
drops.

1. For general process application both L'i.PL and L'i.P g
may be calculated by the general flow equation:
L'i.PL or L'i.P ( using proper values respectively)
g

�m� where f is obtained from Reynolds-Friction Factor
2
3.36fLW (l O -6 )
Intermittent
(2-111)
d5p
chart (Figure 2-3) for an assumed line size, d.
Plug
--2!:3 2. For gas transmission, in general form [33]

Slug (q d 14.65 ) LS g TZf
L'i.P = (2-112)
Distributed g 20 000 d 5 P avg
'
is the thousands cf standard cubic feet
where qd 14 _ 65
of gas per day, measured at 60°F and 14.65 psia, and
Pavg is the average absolute pressure in the pipe sys-
tem between inlet and outlet. This is an estimated
value and may require correction and recalculation
of the final pressure drop if it is very far off.
For oil flow .in natural gas transmission lines [33]

Figure 2·41. Representative forms of horizontal two-phase flow pat- fLQ21,p
terns; same as indicated !n Figure 2-40. By permission, Heim, H., Oil (2-113)
and Gas Journal, Aug. 2, 1982, p.132. 181,916d 5