Page 180 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Fluid Flow I55

t, = Latent heat of evaporation of steam at flash pres- q’m = Free air, cubic feet per minute @ 60°F and 14.7 psia
sure, Btu/lb
R = Individual gas constant = MR/M = 1544/M
1 = Horizontal distance from opening to point where
flow stream has fallen one foot, in. & = Reynolds number, see Figure 2-3
M = MU,’ = molecular weight RH = Hydraulic radius, ft
MR = Universal ga,s constant R, = Ratio of compression at entrance of pipe, Figure 2-
n = Number of vertical rises (or hills) in two-phase pipe 37
line flow r, = Critical pressure ratio = P’,/P’,
or, n = Polytropic exponent in polytropic gas P-V relation- S, = Specific gravity of gas relative to air, (= ratio of mol-
ship ecular weight gas/29)
P = Pressure, psig; or, pressure drop, E’, pounds per
square inch, Babcock Equation 2-82) So = Degrees of superheat in a steam condition, degrees
F above saturated (not the actual temperature)
P, = Absolute pressure, torr
s = Steam quality as percent dryness, fractional
A?, = Pressure drop, torr
SpGr = Specific gravity of fluid relative to water at same
P’ = Pressure, psi absolute (psia)
temperature
P, = Total pressure at lower end of system, psig
T = Absolute Rankin temperature, 460 + t, degrees R
Pbr = Barometric pressure, psi absolute
T, = Standard temperature for gas measurement, ”R =
P, = Total pressure upstream (higher) of system, psig 460 + t
P, = Standard pressure for gas measurement, lbs/sq in. T, = Average flowing temperature of gas, “R
absolute, pria
p” = Pressure, h/sq ft absolute; (in speed of sound t = Temperature, “F
equation, Equation 2-86), Note units. t, = Time interval required for the pressure wave to trav-
p‘ = Gauge pressure, psig el back and forth in a pipe, sec
or, PI = Initial pressure, in. of mercury absolute, vacuum sys- V = Free air flow, cu ft/sec at 60°F and 14.7 psia
tem -
V = Specific volume of fluid, cu ft/lb
AP = Pressure drop, Ibs/sq in, pi; or static loss for flow-
ing fluid, psi V’ = Volume, cu ft
AP, = Pressure drop across a conirol valve, psi V, = Volume, cu ft
AP,,, = Pressure drop in vacuum system due to friction, in. v = Flow velocity (mean) or superficial velocity in pipe
water/100 ft pipe lines at flowing conditions for entire pipe cross sec-
4PTPh = Total two-phase pressure drop for system invohing tion, ft/sec; or reduction in velocity, ft/sec (water
horizontal and vertical pipe, psi per foot of length hammer) -
APloo = Pressure drop, pounds per sq in per 100 ft of pipe v, = Mean velocity in pipe, at conditions of V, ft/min
or equivalent v, = Sonic (critical) velocity in compressible fluid, ft/sec;
Q = Flow rate, gallons per minute, gpm or speed of sound, ft/sec
Qb = Flow rate, barrels/day v,, = Reduction in velocity, ft/sec (actual flowing velocity,
QD = Design flow rate, gpm, or ACFM ft/sec)
QM = Maximum flow rate, gpm, or ACFM W = Flow rate, lhs/hr
q = Flow rate at flowing conditions, cu ft/sec W, = Mass flow rate of liquid phase, pounds per hour per
qd = Gas flow rate standard cubic feet per day, at 60°F square foot of total pipe cross-section area
and 14.7 psia (or 14.65 ifindicated); or flow rate, cu W, = Mass flow rate, lbs/hr/tube
ft/day at base conditions of T, and P,
w = Flow rate, lbs/min
qds = Gzs plow at designated standard conditions, cu
ft/day, cfD w, = Flow rate, lbs/sec; or sometimes, M7,
qh = Gas flow rate, cu ft/hr, at 60°F and 14.4 psiabs, x = Fraction of initial line paralleled with new line
(psi4 Y = Net expansion factor for compressible flow through
q‘ = Cas flow, cu ft/sec, at 14.7 psia and 60°F orifices, nozzles, or pipe
q’h = Flow rate at standard conditions (14.7 psia, and Z = Compressibility factor for gases at average condi-
60°F) cu ft/hr, SCFH
tions, dimensionless. Omit for pressure under 100,
qm = Flow7 rate cu ft/min PSk