Page 139 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Fluid Flow 125

Total System Pressure Drop

Bubble OK 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 1331.
the liquid
AnnUlar: Liquid flows in continuous annular APTP~ = APpT (horizontal pipe) + nhF, pL/144 (2-110)
ring on pipe wall, gas flows through
clenter 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 W, hv/G
2. Calculate G/h
3. Read intersection of ordinate and abscissa to identi-
+ 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 h and ty.

B. Calculate the separate liquid and gas flow pressure
drops.

1. For general process application both APL and APg
may be calculated by the general flow equation:
APL or AP, (using proper values respectively)

- 3.36fLW2 )
- (2 - 111)
d5p

where f is obtained from Reynolds-Friction Factor
chart (Figure 2-3) for an assumed line size, d.

2. For gas transmission, in general form [33]

Ls g TZf
(9 d 14.65
APp = (2 - 112)
20,000 d5Pwg
where qd 14.65 is the thousands of standard cubic feet
of gas per day, measured at 60°F and 14.65 psia, and
P, is the average absolute pressure in the pipe sys-
tem between inlet and outlet. This 6s 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]

we 2-41. Represenlatiwe forms of horizontal two-phase flow pat- fLQ2 hp
terns; same as indicated in Figure 2-40. By permission, Heim, H., Oil APL. = (2-113)
and Gas Journal, Aug. 2, 1982, Q. 132. 181,916 d5