Page 139 - Applied Process Design for Chemical and Petrochemical Plants Volume I

126 Applied Process Design for Chemical and Petrochemical Plants

3. Calculate value times 1.1 to 2.0, depending upon critical
nature of application.
X = (APL/AP,)l/2 (2-114)
APTph = APTP L + n h F,pL/144 (2-118)
4. Calculate 8 for types of flow selected from Figure
2-40 [33].
where pL is the density, lb/cu ft, of the liquid flowing
in the line, and F,, elevation factor using gas veloci-
Type flow Equation for QGIIT ty, v.
Froth or Bubble @ = 14.2 X0.75/Wm0.1
Plug @ = 27.315 X0.s55/W rn 0.17 F, = 0.00967 Wrn0,5/v0,7, for v > 10 (2-119)
Stratified @ = 15,400 X/Wmo.’
Slug Q = 1,190 X0.185/WmO.5
Annular” @ = (4.8 - 0.3125d) X0.348 - 0.021d or as an alternate: F, = 1.7156 Vg-0.’02 (2-1 20)
*Set d = 10 for any pipe larger than 10-in.
X = [APL~~./AP~~~I~’* Use Figure 2-42 for v less than 10. Most gas trans-
mission lines flow at from 1-15 ft/sec.
5. Calculate two-phase pressure drop, horizontal por- For fog or spray type flow, Baker [33] suggests using
tions of lines. For all types of flow, except wave and Martinelli’s correlation and multiplying results by two [46].
fog or spray:
(a) For gas pipe line flow, the values of QGTT may be
AP~~ APG@GTT, psi per foot (2-1 15) converted to “efficiency E” values and used to cal-
=
culate the flow for the horizontal portion using a
For wave [52]. fixed allowable pressure drop in the general flow
equation [33]. The effect of the vertical compo-
APTP = fTp (G’,)‘/193.2 dPg, pSi/fOOt (2-1 1 6) nent must be added to establish the total pressure
drop for the pumping system.
where
-I
fTp = 0.0043 (Wm~L/Gpg)0.214 (2-117) 38.7’744Ts (PI2 - P,‘ )d5
d 14.66 - lOOOP, L,S,TZ
6. Total two-phase pressure drop, including horizon-
tal and vertical sections of line. Use calculated where 14.65 refers to reference pressure P,.

Liquid Head
Factor, F,
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.
I

Superficial Gas Velocity, ft./sac.
Figure 2-42. Estimating pressure drop in uphill sections of pipeline for two-phase flow. By permission, 0. Flanigan, Oil and Gas Journal, Mar.
10, 1958, p. 132.