Page 146 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

132 Applied Process Design for Chemical and Petrochemical Plants

ABSOLUTE VISCOSITY X IW WOUNDS PER FOOT.SECOND

REYNOLDS NUMBER Rn = 5

Figure 2-44. Friction factor for streamlined flow of air at absolute
pressures from 50 microns Hg. to lmm Hg. By permission, Stan- ABSOLUTE VISCOSITY OF AIR
dards for Steam Jet Ejectors, 3rd. Ed., Heat Exchange Institute, 1956
[54] and Standards for Steam Jet Vacuum Systems, 4th Ed., 1988. Figure 2-45. Absolute viscosity of air. By permission, Standards for
Note: f on same basis as Figure 2-3 [Cis]. Steam Jet Ejectors, 3rd Ed., Heat Exchange Institute, 1956 [54]; also,
Standards for Steam Jet Vacuum Systems, 4th Ed., 1988 [58].
(text continued from page 129)
5. Determine Reynolds hTumber, %. 8. Calculate the pressure drop for the specific line sec-
tion (or total line) from:
(2-1 5)
APT = 0.625 pif Lqm2/d5, torr (2-130)

p = density, lb/cu ft at flowing conditions
D = pipe inside diameter, ft or, = 4.31 pif Lv2/2gd, torr (2-1 30A)
v = vapor velocity (actual), ft/sec
p, = viscosity of vapor, lb/ft-sec where p = density, lb/cu ft
d = pipe inside diameter, in.
qm = volumetric flowrate, cu ft/min
6. Determine friction factor, f, from Moody Friction f = friction factor, (Moody) Figure 2-3
Factor Charts, Figure 2-3. APT = pressure drop, torr

or, calculate for turbulent flow using Blausius' equa- Calculate: pi = PiM/555Ti, lb/cu ft (2-131)
tion [18]:
Pi = pressure, torr
M = average molecular weight of mixture flowing
f = 0.316/(%)1/4, for R, < 2.0 X lo5 Ti = temperature, "R

'7. Tabulate the summation of equivalent lengths of 9. If the calculated pressure drop does not exceed the
straight pipe, valves, fittings, entrance/exit losses as maximum given in Figure 2-47, use this calculated
presented in earlier sections of this chapter. value to spec@ the line. If the AP exceeds the limit